Browse Topic: Coolants

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Innovative Control and Monitoring Algorithms and Strategies Based on Judicious Functional Partitioning and Frugal Engineering Concepts2021-01-01244/6/2021
As embedded electronic control systems are increasingly penetrating vehicle subsystems, the designers are faced with a dilemma of providing state of art vehicle features on one hand and ensuring frugal implementation of the same to meet competitive pressures on the other. For embedded software and hardware systems this means adoption of judicious and innovative design choices with reusable building blocks. This paper dwells upon various design aspects of control and monitoring which are frequently used for automotive applications such as feed-forward and proportional integral control, diagnostics for sensor boundary conditions, handling of intermittent faults without causing nuisance to the vehicle users etc.
Vaidya, Vishwas Manohar
Modeling and Design of a Wet Clutch Offset Compound Gear Transmission for Dual-Speed Rotorcraft ApplicationsF-0076-2020-1633610/5/2020
This paper develops a lumped-parameter multi-plates wet clutch Offset Compound Gear (OCG) transmission dynamics and its thermal model for dual-speed rotorcraft applications with an active clutch slip-speed control. This model includes the Reynolds equation for the clutch oil film thickness, the clutch thermal model, the clutch transferred torques (viscous and asperity torque) and the clutch disengagement model. The wet clutch/OCG transmission system is implemented in Matlab® Simulink™ to manage the upshift clutch temperature rise, which is a main issue need to handle for a dual-speed helicopter transmission. Here, the clutch temperature rise is treated by injecting a certain amount of coolant during engagement so that the temperature rise for the wet clutch is much lower than that of an dry clutch. In order to transfer a required torque using the available power, the sizing of the wet clutch could be evaluated via the developed wet clutch/OCG transmission model. This study shows that the temperature rise drops as the wet clutch oil flow rate increases adding extra weights compared with the dry clutch. The simulation also captures a phenomenon that a larger clutch engagement pressure might be required for the wet clutch to transfer the same torque since the wet clutch oil viscosity drops as the oil temperature increases during the clutch engagement.
DeSmidt, Hans, Bill, Robert, Su, Xiaowen, Smith, Edward
Experimental Analysis of a Multiple Radiator Cooling System with Computer Controlled Flow Rates2020-01-09444/14/2020
The automotive cooling system configuration has remained fixed for many decades with a large radiator plus fan, coolant pump, and bypass valve. To reduce cooling system power consumption, the introduction of multiple computer-controlled heat exchangers may offer some benefits. A paradigm shift from a single large radiator, sized for maximum load, to n-small radiators with individual flow control valves should allow fine tuning of the heat rejection needs to minimize power. In this project, a series of experimental scenarios featuring two identical parallel radiators have been studied for low thermal load engine cooling (e.g., idling) in ground transportation applications. For high thermal load scenarios using two radiators, the fans required between 1120 - 3600 W to maintain the system about the coolant reference temperature of 85oC. In contrast at reduced thermal loads, a single radiator configuration with half the heat transfer surface area required between 550 - 1000 W for the same operating conditions. A 51% reduction in fan and pump power consumption at a lower thermal load, while maintaining coolant temperature about the setpoint value, offers possibilities on redesigning the thermal management system. Given that vehicles often operate at reduced thermal loads, these findings can help improve the overall powertrain performance.
Syed, Zaker, Wagner, John
3-Dimensional Numerical Simulation on CuO Nanofluids as Heat Transfer Medium for Diesel Engine Cooling System2020-01-11094/14/2020
CuO-water nanofluids was utilized as heat transfer medium in the cooling system of the diesel engine. By using CFD-Fluent software, for 0.5%, 1%, 3% and 5% mass concentration of nanofluids, 3-dimensional numerical simulation about flow and heat transfer process in the cooling system of engine was actualized. According to stochastic particle tracking in turbulent flow, for solid-liquid two phase flow discrete phase, the moving track of nanoparticles was traced. By this way, for CuO nanoparticles of different mass concentration nanofliuds in the cooling jacket of diesel engine, the results of the concentration distribution, velocity distribution, internal energy variation, resident time, total heat transfer and variation of total pressure reduction between inlet and outlet were ascertained. It is proved by simulation results that nanofluids as heat transfer medium can evidently enhance diesel engine heat transfer capability, when the concentration of nanoparticles increases, the enhancement of heat transfer capacity increases, power loss of water pump also increases in small scale, the relativity between the average resident time of CuO nanoparticles and CuO nanoparticles concentration is not clear in cooling jacket, the relativity between heat transfer efficiency of CuO nanoparticles and nanofliuds flow velocity is not clear.
Yang, Shuai, Yang, Xiaolin, Liu, Haifeng, Li, Xiuyuan
Off-Road Self-Propelled Work Machines Operator Enclosure Environment Part 1: Terms and DefinitionsJ3078/1_202001 (Current)1/29/2020
SAE J3078 provides test methods and criteria for the evaluation of the operator enclosure environment in earth-moving machinery as defined in ISO 6165. SAE J3078/1 gives the terms and definitions which are used in other parts of SAE J3078. It is applicable to Off-Road Self-Propelled Work Machines as defined in SAE J1116 and Agricultural Tractors as defined in ANSI/ASAE S390.
HFTC6, Operator Accommodation
Replacing Twin Electric Fan Radiator with Single Fan Radiator2019-28-238111/21/2019
Downsizing is one of the crucial activities being performed by every automotive engineering organization. The main aim is to reduce - Weight, CO2 emissions and achieve cost benefit. All this is done without any compromise on performance requirement or rather with optimization of system performance. This paper evaluate one such optimization, where-in radiator assembly with two electric fan is targeted for downsizing for small commercial vehicle application. The present two fan radiator is redesigned with thinner core and use of single fan motor assembly. The performance of the heat exchanger is tested for similar conditions back to back on vehicle and optimized to get the balanced benefit in terms of weight, cooling performance and importantly cost. This all is done without any modification in vehicle interface components except electrical connector for fan. The side members and brackets design is also simplified to achieve maximum weight reduction. Further Cooling system performance of engine is evaluated along with Fuel efficiency; results are compared with present configuration.
Bhargava, Aashish, Soni, Gaurav, Warkhade, Tushar
Miniature Stretchable PumpTBMG-3529610/1/2019
Soft robots have a distinct advantage over rigid robots: they can adapt to complex environments, handle fragile objects, and interact safely with humans. Made from silicone, rubber, or other stretchable polymers, they are ideal for use in rehabilitation exoskeletons and robotic clothing. Soft bio-inspired robots could one day be deployed to explore remote or dangerous environments.
Using Laser Metal Printing to Cool Computer ChipsTBMG-345956/1/2019
Traditionally, electronics are cooled using a heat sink that transfers the heat generated by the electronic system into the air or a liquid coolant. For the heat sink to work, it has to be attached to the CPU or the graphics processor via a thermal interface material such as thermal paste. It helps facilitate the transfer of heat by bridging microscopic gaps between the heat sink and the chip.
Application of Electrically Driven Coolant Pumps on a Heavy-Duty Diesel Engine2019-01-00741/15/2019
A reduction in CO2 emissions and consequently fuel consumption is essential in the context of future greenhouse gas limits. With respect to the thermodynamic loss analysis of an internal combustion engine, a gap between the net indicated thermal efficiency and the brake thermal efficiency is recognizable. This share is caused by friction losses, which are the focus of this research project. The parasitic loss reduction potential by replacing the mechanical water pump with an electric coolant pump is discussed in the course of this work. This is not a novel approach in light duty vehicles, whereas in commercial vehicles a rigid drive of all auxiliaries is standard. Taking into account an implementation of a 48-V power system in the short or medium term, an electrification of auxiliary components becomes feasible. The application of electric coolant pumps on an Euro VI certified 6-cylinder in-line heavy-duty diesel engine regarding fuel economy was thus performed. The engine has two cooling circuits, one low temperature circuit for the charge air coolers and one high temperature circuit as main circuit, which are split in two separate circuits. This layout provides the opportunity to determine the charge air temperature level on demand, which may on the one hand be used for lower NOx emissions, or on the other hand enable exhaust gas heating. Moreover, an operating strategy with respect to a reduced coolant flow rate is investigated and the advantages in the brake thermal efficiency are determined. Future emission tests will include real driving and cold-start phases also for heavy-duty application, where an optimized thermal management will play a key role. The influence of the modified cooling system layout on the warm-up in the worldwide heavy-duty transient cycle is thus presented. Furthermore, the additional degree of freedom offers the possibility to run the pump after the engine is turned off. This post-run phase and its benefits on component protection will also be presented.
Granitz, Christina, Ratzinger, Josef, Eichlseder, Helmut, Surace, Alfonso
An Experimental Study of the Effects of Coolant Temperature on Particle Emissions from a Dual Injection Gasoline Engine2019-01-00511/15/2019
Euro VI emission standards have set a very strict limitation on particulate matter emissions of Gasoline Direct Injection (GDI) engine. It is difficult for GDI engine to meet the Euro VI PN regulation (6×1011#/km) without a series of complicated after-treatment devices such as Gasoline Particulate Filter (GPF). Previous research shows that GDI vehicles under cold start condition account for more than 50% of both particle number and mass emissions during the entire NEDC driving cycle. Dual Injection Gasoline engine is based on the GDI engine by adding a set of port fuel injection system. The good mixing characteristics of the port fuel injection system can help to reduce the particulate matter emissions of the GDI engine during the cold start condition. In this study, a Cambustion DMS500 fast particle spectrometer was employed to characterize the effects of coolant temperature and direct injection ratio on particulate emissions from a turbocharged four-cylinder dual-injection gasoline engine. The experimental results showed that with the coolant temperature increasing the particulate matter tended to be consistent under the port fuel injection mode. The particulate matter showed significantly drop with the coolant temperature increasing both in the dual injection mode and the direct injection mode. At the same coolant temperature, with the decrease of the direct injection ratio, the particulate matter showed notably reductions, and with the increase of coolant temperature, the magnitude of the reductions gradually declined. The experimental results provided important guidance to reduce the particulate matter via dual injection mode during the cold start condition.
Xia, Chun, Chen, Wenhao, Fang, Junhua, Huang, Zhen
Reliability Case Analysis of an Autonomous Air Cooling System (AACS) for Aerospace Applications2018-01-191610/30/2018
Current More Electric Aircraft (MEA) utilize Liquid Cooling Systems (LCS) for cooling on-board power electronics. In such LCS, coolant pipes around the structure of the aircraft are used to supply water glycol based coolant to sink heat from power electronics and other heat loads in the electronic bay. The extracted heat is then transferred to ram air through downstream heat exchangers. This paper presents a reliability examination of a proposed alternative Autonomous Air Cooling System (AACS) for a twin engine civil MEA case study. The proposed AACS utilizes cabin air as the coolant which is in turn supplied using the electric Environmental Control System (ECS) within the MEA. The AACS consists of electrical blowers allocated to each heat load which subsequently drive the outflow cabin air through the heat sinks of the power electronics for heat extraction. No additional heat exchanger is required after this stage in which the heated air is directly expelled overboard. One key advantage is the avoidance of liquid coolant leakage with the removal of liquid coolant from the MEA. It is necessary that the expected reliability of the AACS is in line with the equivalent LCS and is compliant with Federal Aviation Administration/previous Joint Aviation Authorities (FAA/JAA) reliability limits. Accordingly, this paper evaluates the reliability of the proposed AACS as well as the subsequent operation of safety critical components of the ECS and Electrical Power System (EPS) that the AACS is cooling. The analysis results show that the proposed AACS can provide comparable reliability to an LCS and is expected to be compliant with FAA/JAA reliability limits.
Fong, Chung Man, Norman, Patrick, Seki, Naoki
Variation in System Performance while Sorting DEF Heating Hardware Options2018-01-18139/10/2018
The desire to reduce NOx at low ambient temperatures drives the use of heating methods to make DEF available by thawing the solution in the tank. Methods to validate modelling used to design hardware options require testing to gauge the accuracy of the prediction. Using a climatic chassis dynamometer (CCD) to demonstrate the guidance procedure set by the Environmental Protection Agency (EPA) is expensive and time consuming. A method of utilizing a flow controlled cooling supply combined with a standard cold chamber is described as a precursor to running the demonstration in the CCD. Testing multiple quantities of design iterations produced unexpected variation in the results. The sources of the variation and modifications taken to minimize them are discussed and presented. Test to test control of coolant flow, coolant temperature, and specific chamber temperature inconsistencies were found to be critically important to a successful effort. Several design iterations were compared with varying degrees of success. The method was modified as variation between tanks of the same design was noted. System description details as well as modifications to the process are discussed. A design that maximizes heat transfer to the DEF pick up area while providing enough heat to melt the remainder of the volume was found to clearly out-perform the others. Test apparatus details are described. The DEF heating loop system is exposed to varying temperatures and flows in the truck. Selection of a representative coolant flow and temperature is discussed. The EPA certification test method options are referenced. Control parameters are defined with the intent of demonstrating a test practice that minimizes CCD time and ultimately accurately predicts hardware performance on the certification test.
Vermiglio, Ezio, Gilliam, Kyle, Chin, Anthony, Leonard, Treaver, Erickson, Darren
Taming the Thermal Behavior of Solid-State Military LasersTBMG-290826/1/2018
Laser diodes and laser diode arrays (LDAs) are widely used throughout military systems, for sighting and range finding, but also at high power levels as offensive and defensive weapons. In companion with much higher-power chemical lasers, these high-power optical sources can generate kilowatts of optical power (as arrays) for use in neutralizing incoming missiles, rockets, and armaments and for long-distance offensive strikes. But laser diodes are also still inefficient, and a great deal of the energy supplied to a laser diode or an LDA is converted into heat, which must be safely dissipated to ensure a long operating lifetime for the solid-state devices.
A Model Predictive Approach to Avoid Coolant After-Boiling in ICE2018-01-07794/3/2018
The after-boiling phenomenon in internal combustion engines can occur when the engine is suddenly switched-off after a period of prolonged high-load operation. In this case, the coolant flow rate stops while the engine wall temperature is quite high; therefore, some evaporation occurs, pressure in the cooling circuit increases and part of the coolant is lost through the radiator relief valve. The control of the coolant flow rate by means of an electric pump instead of the standard belt driven one offers the possibility of overcoming this issue. In the present paper, a model-based control of the coolant flow rate is proposed in conjunction with the adoption of an electric pump in the engine cooling system. Experimental tests and simulations have been carried out starting from high speed-high load engine operation; the engine was then brought to idle and, shortly after, switched-off. A comparison with the adoption of the standard belt-driven pump in the cooling system lay-out is presented in order to evaluate the effectiveness of the proposed approach.
Castiglione, Teresa, Morrone, Pietropaolo, Bova, Sergio
Thermodynamic Cycle and Working Fluid Selection for Waste Heat Recovery in a Heavy Duty Diesel Engine2018-01-13714/3/2018
Thermodynamic power cycles have been shown to provide an excellent method for waste heat recovery (WHR) in internal combustion engines. By capturing and reusing heat that would otherwise be lost to the environment, the efficiency of engines can be increased. This study evaluates the maximum power output of different cycles used for WHR in a heavy duty Diesel engine with a focus on working fluid selection. Typically, only high temperature heat sources are evaluated for WHR in engines, whereas this study also considers the potential of WHR from the coolant. To recover the heat, four types of power cycles were evaluated: the organic Rankine cycle (ORC), transcritical Rankine cycle, trilateral flash cycle, and organic flash cycle. This paper allows for a direct comparison of these cycles by simulating all cycles using the same boundary conditions and working fluids. To identify the best performing cycle, a large number of working fluids were evaluated with regards to the maximum power output of the power cycle for each heat source. Taking into account the constraints and boundary conditions, this study shows that the ORC gives the best performance with a power output of around 1.5 kW for the coolant, 2.5 kW for the exhaust gas recirculation cooler, and 5 kW for the exhaust with acetone, cyclopentane and methanol as the best performing working fluids.
Rijpkema, Jelmer, Andersson, Sven, Munch, Karin
System-Level Investigation of Traction Inverter High-Temperature Operation2018-01-04644/3/2018
In this paper, the high-temperature capability of the traction inverter was investigated by applying coolant with temperature much higher than the typical allowed value until the system fails. The purpose of this study is to identify the weakest link of the traction inverter system in terms of temperature. This study was divided into two stages. In the first stage, a series of nondestructive tests were carried out to investigate temperature rise (ΔT) of the key component above coolant temperature as a function of the outside controllable parameters-i.e., dc link voltage, phase current, and switching frequency. The key components include power modules, gate driver board, gate driver power supply, current sensors and dc link capacitor. Their temperatures were monitored by thermocouples or on-die temperature sensors. The result showed that temperature rises of most key components were strongly affected by phase current, moderately affected by switching frequency, and slightly affected by dc link voltage. Therefore, the operating conditions used in the second stage (destructive test) were chosen to stress the phase current only rather than the dc link voltage and switching frequency for better effectiveness. In the second stage (the destructive test), the coolant temperature was controlled to increase every a few hours after the temperature stabilized while maintaining the controllable electrical parameters to be the same. Testing results showed that the traction inverter employed in this study can sustain coolant temperature > 105 °C for more than 10 hours, while the IGBT on-die temperatures were measured to be >200 °C. Under this specific condition, the IGBT module is the first component to fail after the coolant temperature was raised to a certain level (>120 °C). On the contrary, many other components are found to be functioning after the long-time operation at high temperatures. The measurement results were confirmed by the theoretical analysis.
Lu, Xi, Xiao, Kewei, Lei, Guangyin, Chen, Chingchi
Development of Parallel and Direct Cooling System for EV/FCEV Inverter2018-01-04544/3/2018
This paper presents the direct liquid-cooled power module with the circular pin fin which is the inverter parallel cooling system for high output EV/FCEV. The direct cooling system of a conventional inverter is designed to supply coolant along the direction in which the heating element such as Si-chip is disposed and discharge coolant to the opposite side. In case of the inverter, the higher the output is, the larger temperature difference between inlet and outlet becomes due to the heat exchange of the heat generation element, so that temperature difference depends on the position of Si-chip. Since lifetime is judged on the basis of maximum temperature of Si-chip, the inverter itself must be replaced or discarded due to durability of the inverter even though Si-chip can drive further. The simple way to solve this problem is to increase cooling flow rate, but this leads to excessive increase in pressure loss due to circular pin fin. Purpose of this study is the concept of parallel cooling system which improves junction temperature of Si-chip and pressure loss in cooling channel at once without increasing flow rate when configuration of the circular in-fin is fixed. Numbers of geometries of parallel cooling channel have been modeled for optimization. The decrease in rising temperature of the best geometry achieved about 2.4% which is the same result as 15.6% increase of flow rate compared to conventional design at 8 L/min on 450 V, 8 kHz switching frequency. However, the pressure loss of the best geometry was reduced by 36%.
Seo, Heung Seok, Shin, Dongmin
System Characteristics of Direct and Secondary Loop Heat Pump for Electrical Vehicles2018-01-00634/3/2018
The electricity energy consumption for passenger cabin heating can drastically shorten the driving range for electric vehicles in cold climates. Mobile heat pump system is considered as an effective method to improve heating efficiency. This study investigates the system characteristics of mobile heat pump systems for electrical vehicle application. Based on KULI thermal management software, simulation models including HFC-R134a direct heat pump (DHP) and secondary loop heat pump (SLHP) were developed. The secondary loop employed in the SLHP includes a coolant pump, an indoor heater core and a plate heat exchanger, instead of an indoor condenser in the DHP. The use of a secondary loop has advantages to improve air outlet temperature uniformity. The simulation models were verified by measured data obtained from calorimeter experiments. By adopting simulation models, the effects of indoor and outdoor temperatures on system performance and cycle characteristics were discussed. Results show that the increase of indoor temperature will largely decrease the system efficiency, and varied outdoor temperature has a big impact on heating capacity. Then the comparison simulations between DHP and SLHP were conducted, to determine the effect of the secondary loop on heating performance. Results show that the use of a secondary loop is severely harmful to system efficiency, but has little effect on heating capacity. Furthermore, the impact of coolant flow rate on the capacity and COP was discussed, and heat transfer effectiveness of heater core and plate heat exchanger were also evaluated.
Wang, Dandong, Gao, Tianyuan, Li, Wanyong, Yang, Yun, Shi, Junye, Chen, Jiangping
An Experimental Study on the Knock Mitigation Effect of Coolant and Thermal Boundary Temperatures in Spark Ignited Engines2018-01-02134/3/2018
Increasing compression ratio is essential for developing future high-efficiency engines due to the intrinsic characteristics of spark-ignited engines. However, it also causes the unfavorable, abnormal knocking phenomena which is the auto-ignition in the unburned end-gas region. To cope with regulations, many researchers have been experimenting with various methods to suppress knock occurrence. In this paper, it is shown that cooling the combustion chamber using coolants, which is one of the most practical methods, has a strong effect on knock mitigation. Furthermore, the relationship between thermal boundary and coolant temperatures is shown. In the beginning of this paper, knock metrics using an in-cylinder pressure sensor are explained for readers, even though entire research studies cannot be listed due to the innumerableness. The coolant passages for the cylinder head and the liner were separated to examine independent cooling strategies. In addition, piston surface temperature was changed through the oil supply to the piston oil gallery. To investigate the effects on the thermal boundary temperature under knocking conditions, temperatures were measured. Knock mitigation effects were quantified while the coolant temperatures were varied. Quantification in this study consists of two methods: The advancement of the crank angle ignition timing and the expansion of the borderline knock (detonation border line). The different impacts of cooling between PFI (port fuel injection) and GDI (gasoline direct injection) engines and the differences under various S/B (stroke-to-bore) ratios are also shown in this study. After implementation, it was shown that decreasing the coolant temperature in the cylinder head has a greater effect than that of the liner. Furthermore, 4.2 CA and 5 CA of ignition timing advance and 10% and 6.8% of knock load limit expansion were achieved while the coolant temperature was decreased from 85 °C to 60 °C under 1500 rpm and 2000 rpm, respectively. GDI engine also showed knock mitigation effects by the coolant temperature decrease. Higher stroke-to-bore ratio led to expanded load limit due to increased knock suppression. However, there was no significant difference in the effect of coolant temperature decrease for various stroke-to-bore ratios.
Cho, Seokwon, Song, Chiheon, Oh, Sechul, Min, Kyoungdoug, Ha, Kyoung-Pyo, Kim, Back-Sik
Development and Validation of a Submodel for Thermal Exchanges in the Hydraulic Circuits of a Global Engine Model2018-01-01604/3/2018
To face the current challenges of the automotive industry, there is a need for computational models capable to simulate the engine behavior under low-temperature and low-pressure conditions. Internal combustion engines are complex and have interconnected systems where many processes take place and influence each other. Thus, a global approach to engine simulation is suitable to study the entire engine performance. The circuits that distribute the hydraulic fluids -liquid fuels, coolants and lubricants- are critical subsystems of the engine. This work presents a 0D model which was developed and set up to make possible the simulation of hydraulic circuits in a global engine model. The model is capable of simulating flow and pressure distributions as well as heat transfer processes in a circuit. After its development, the thermo-hydraulic model was implemented in a physical based engine model called Virtual Engine Model (VEMOD), which takes into account all the relevant relations among subsystems. In the present paper, the thermo-hydraulic model is described and then it is used to simulate oil and coolant circuits of a diesel engine. The objective of the work is to validate the model under steady-state and transient operation, with focus on the thermal evolution of oil and coolant. For validation under steady-state conditions, 22 operating points were measured and simulated, some of them in cold environment. In general, good agreement was obtained between simulation and experiments. Next, the WLTP driving cycle was simulated starting from warmed-up conditions and from ambient temperature. Results were compared with the experiment, showing that modeled trends were close to those experimentally measured. Thermal evolutions of oil and coolant were predicted with mean errors between 0.7 °C and 2.1 °C. In particular, the warm-up phase was satisfactorily modeled.
Broatch, Alberto, Olmeda, Pablo, Martin, Jaime, Salvador-Iborra, Josep
Impact on Fouling of Different Exhaust Gas Conditions with Low Coolant Temperature for a Range of EGR Cooler Technologies2018-01-03744/3/2018
Degradation of anti-pollutant devices must be taken into account in design so durability of the function is guaranteed over the vehicle lifetime. As for NOx reduction of diesel engines, Exhaust Gas Recirculation (EGR) systems are a well-known and robust solution. However, exposure of the EGR cooler inside this system to the exhaust gas conditions leads to a degradation of its function, affecting to the EGR rate and therefore to potential for NOx reduction. So, sizing and technology of these heat exchangers must be selected to avoid malfunction during vehicle operation. Current scenario in Europe with new homologation cycles and focus on NOx emissions of diesel vehicles under real driving conditions is challenging for the design of EGR systems. This leads to the increase of the areas of the engine map using EGR. Moreover new homologation includes also the use of low ambient temperature. In this context, it is important to understand the impact of critical exhaust gas conditions coupled with low EGR coolant temperature. That is to say, the use of low coolant temperature adds condensation to the typical phenomenon of soot deposition, thus making it even more critical since condensation puts in to the thermophoresis a significative impact in the formation of the fouling layer. As the impact varies according to the heat exchanger technology, a set of tests has been performed in order to analyze the effect in the two main functions: thermal efficiency and pressure drop. Six different technologies have been tested: from round to rectangular corrugated tubes, and tubes with fins with different design parameters. Most critical conditions of exhaust gas have been taken in terms of opacity and HC content, as well as the effect of using nominal coolant temperature versus low coolant temperature have also been analyzed. This study enables to discriminate most suitable technologies for different engine conditions. Further work is planned in order to study soot characterization and representativeness in lifetime of the vehicle.
Bravo, Yolanda, Arnal, Cristina, Larrosa, Carmen, Climent, Hector
Parallel Thermal Management System of the Water Medium Retarder2018-01-07774/3/2018
The thermal management system of the water medium retarder using engine coolant (water and ethylene glycol) as transmission medium, omits oil-water heat exchanger in the structure. When the hydraulic retarder is operated, the valve is connected with the retarder and water pump, and then the engine coolant enters the working chamber. The kinetic energy of the vehicle is converted into internal energy of the coolant, and the heat is discharged to the external environment through the engine thermal management system. The braking torque of the water medium hydraulic retarder is determined by the water medium flow rate in the working chamber. The smaller the valve opening degree, the greater the braking torque and the faster the heating transmission fluid. Small valve opening is not conducive to the loss of heat. It will affect the normal working of the engine and hydraulic retarder. In this paper, the thermal management system of the water medium hydraulic retarder is independent of the engine. Hydraulic retarder can be controlled individually so that to improve the auxiliary braking performance. Firstly, the independent thermal management system is designed according to the heat dissipation requirement of the hydraulic retarder. Secondly, the heat transfer of the hydraulic retarder thermal management system is analyzed. Finally, compare to the thermal management system of the traditional water medium retarder and the paper. The results show that the thermal management system of parallel water medium hydraulic retarder can effectively use the radiator cooling capacity, and reduce the working temperature of the water hydraulic retarder.
Gao, Xin, Lei, Yulong, Chen, Wei, Cui, Guokai, Zhong, Lei
Effect of Thermal Management on Engine Performance2018-01-02244/3/2018
The effect of engine coolant and oil temperature on the performance was experimentally evaluated on a Navistar 12.4 Liter engine. The engine speed and load selected for evaluation represented the engine conditions typically found during a Class-8 truck’s cruising operation. In order to study the effect of oil and coolant temperature in isolation, the production coolant-cooled oil-cooler was replaced with a separate oil and coolant conditioning system. The piston and liner surface temperature was also logged at select locations to provide solid temperature response to coolant and oil temperature changes. The engine tests showed that oil temperature variation had greater impact on the engine performance compared to the coolant temperature. This performance improvement came primarily from the lower combustion heat rejection and reduced friction at moderate engine loads. At higher engine loads the performance improvement was largely due to lowered heat rejection. Engine operation at elevated coolant temperatures resulted in slightly higher exhaust enthalpy with little or no change to the engine performance. The liner and the piston temperature provided continuous feedback and helped to successfully navigate the engine through these areas of elevated coolant and oil temperature.
Rajkumar, M., Vojtech, Ryan, Cigler, James
CFD Simulation on Nanofluid Coolant of Gasoline Direct Injection Engine2017-01-221910/8/2017
The conventional cooling fluids in vehicle engine cooling water jacket have relatively poor heat transfer performance. The key to enhance heat transfer in cooling-jacket is to research a kind of new coolants. Nanofluids have heat transfer enhancement merits. In present study, the numerical simulation on Fe3O4 nanofluid flow in cooling water jacket of Gasoline direct injection engine was performed using computational fluid dynamics ( CFD) software FLUENT. The heat transfer coefficient of nanofluids was calculated and verified by experiment. Fe3O4 nano-particles were used in mixture of water/ethylene glycol as a base fluid. The thermal performance of the nanofluid was studied, also the thermal performance of a cooling-jacket was studied with CFD technology. The simulation was performed for different volumetric concentrations of(1%,2%,5%) nanofluids at different engine speeds. The results showed that heat transfer enhanced compared to the base fluid. But the pressure loss enlarged in cooling-jacket with nanofluids. The heat transfer coefficient enhancement about 62.5% compared to the base fluid with 5% volume percent, but the max pressure loss about 45kpa in the cooling-jacket. Then the influence of heat transfer enhancement on vehicle energy consumption was analyzed.
Wang, Xihui
Control for Electrical Coolant Valve in Engine Thermal Management Module2017-01-220410/8/2017
Hyundai-Kia Motor Company recently developed a multi-way, electrical coolant valve for engine thermal management module (TMM). The main purposes of the TMM are to boost fuel economy by accelerating engine warm-up and also to enhance engine thermal efficiency by actively controlling the operating temperature. In addition to those, the system can improve vehicle heating and cooling performance as well. The electrical coolant valve is a key component in the TMM as it modulates the amount of coolant flow to individual components in cooling system such as engine oil heat exchanger, heater core, and radiator. The coolant flow modulation is done by controlling the electric valve’s position with using an electric motor attached to the valve. The objective of the valve control is to manage coolant temperature at a desired level that varies depending on vehicle’s operating condition. This paper discusses the control algorithm developed for controlling electrical coolant valve. The algorithm is designed to force engine coolant temperature to robustly follow the desired temperature target under disturbance from engine operating condition variation. In order to deal with the time delay between valve action and the actual impact on temperature change, the controller utilizes two water temperature sensors located at the inlet and the outlet of engine water jacket circuitry. The result acquired through actual prototype vehicle tests is also demonstrated.
Lee, Hoon, Jeong, Kwangwoo, Yoo, Sanghoon, Lee, Byungho, Kim, Sejun
Glow Plug Assisted Compression Ignition (GA-CI) in Cold Conditions2017-01-228810/8/2017
Low temperature combustion (LTC) is an advanced combustion mode, which can achieve low emissions of NOx and PM simultaneously, and keep relatively high thermal efficiency at the same time. However, one of the major challenges for LTC is the cold condition. In cold conditions, stable compression ignition is hard to realize, while thermal efficiency and emissions deteriorate, especially for gasoline or fuel with high octane number. This study presents using pressure sensor glow plugs (PSG) to realize Glow plug assisted compression ignition (GA-CI) at cold conditions. Further, a glow plug control unit (GPCU) is developed, a closed-loop power feedback control algorithm is introduced based on GPCU. In the experiment, engine coolant temperature is swept. Experimental results show that GA-CI has earlier combustion phases, larger combustion duration and higher in-cylinder pressure. And misfire is avoided, cycle-to-cycle variations are greatly reduced. Moreover, though NOx emissions rise slightly, significant reductions of CO emissions HC emissions and PM emissions are observed. Further analysis shows that under GA-CI the combustion efficiency is enhanced nearly 2% at all test points. The glow plug plays a role of a hot spot that increases the temperature of neighboring region and the reactivity of the charge in this region. As a result, it triggers the inhomogeneous charge and helps to realize better combustion process under cold condition.
Zhou, Tianyuan, Yao, Changsheng, Yang, Fuyuan, Jinwei, Sun
The Research of the Heavy Truck’s Warming System2017-01-222110/8/2017
It’s not easy to start the engine in winter, especially in frigid highlands, because the low temperature increases the fuel’s viscosity, decreasing the lubricating oil flow ability and the storage performance of battery. Current electrical heating method can improve the engine starting performance in low temperature condition, but this method adds an external power to the engine, leading to the engine cannot maintain an efficient energy utilization. A warming device using the solar energy is designed to conserve the energy during the daytime, and directly warm up the engine at the time when the engine turns off for a long time, especially during the night. A solar collector installed on the top of the vehicle is used to convert the solar energy to the thermal energy, which is then transferred to the heat accumulator that contain the phase-change medium which can increase the heat storage performance. The solar energy is best used to supply for the engine warming system with the warming device. As a result, it can increase coolant’s initial temperature to reduce the per-heating time, so that prolong the engine’s service-life and decrease engine’s exhaust emission.
Zeng, Peixuan, Zhang, Penghao, Mei, Binyu, Huang, Shiping, Tan, Gangfeng
Effect of EGR Temperature on PFI Gasoline Engine Combustion and Emissions2017-01-223510/8/2017
In order to investigate the impacts of recirculated exhaust gas temperature on gasoline engine combustion and emissions, an experimental study has been conducted on a turbocharged PFI gasoline engine. The engine was equipped with a high pressure cooled EGR system, in which different EGR temperatures were realized by using different EGR coolants. The engine ran at 2000 r/min and 3000 r/min, and the BMEP varied from 0.2MPa to 1.0MPa with the step of 0.2MPa. At each case, there were three conditions: 0% EGR, 10% LT-EGR, 10% HT-EGR. The results indicated that LT-EGR had a longer combustion duration compared with HT-EGR. When BMEP was 1.0 MPa, CA50 of HT-EGR advanced about 5oCA. However, CA50 of LT-EGR could still keep steady and in appropriate range, which guaranteed good combustion efficiency. Besides, LT-EGR had lower exhaust gas temperature, which could help to suppress knock. And its lower exhaust gas temperature could reduce heat loss. These contributed to fuel consumption reduction. For HT-EGR and LT-EGR, IMEP was similar at every operating point, but LT-EGR had lower pumping loss than HT-EGR, which also helped to reduce fuel consumption. Based on the above-mentioned factors, it was found that LT-EGR could help to reduce fuel consumption by 1%~ 2%, and the fuel efficiency improvement was better at high loads. Engine emissions were also discussed.
Liu, Ting, Zhang, Fuyuan, Chao, Yuedong, Hu, Zongjie, Li, Liguang
A Study on the Effect of Elevated Coolant Temperatures on HD Engines2017-01-222310/8/2017
In recent years, stricter regulations on emissions and higher demands for more fuel efficient vehicles have led to a greater focus on increasing the efficiency of the internal combustion engine. Nowadays, there is increasing interest in the recovery of waste heat from different engine sources such as the coolant and exhaust gases using, for example, a Rankine cycle. In diesel engines 15% to 30% of the energy from the fuel can be lost to the coolant and hence, does not contribute to producing work on the piston. This paper looks at reducing the heat losses to the coolant by increasing coolant temperatures within a single cylinder Scania D13 engine and studying the effects of this on the energy balance within the engine as well as the combustion characteristics. To do this, a GT Power model was first validated against experimental data from the engine. Using a Water-PEG mixture as coolant, the coolant temperature was then varied from 60°C to 200°C for both the liner and the cylinderhead. This sweep was done for multiple combinations of engine loads and speeds as well as for different air-fuel ratios. It was found that at the higher air-fuel ratios, an increase in coolant temperature led to an increase in indicated efficiency as well as an increase in exhaust gas temperature and enthalpy. However at lower air-fuel ratios there is a decrease in indicated efficiency with higher coolant temperatures. It was also seen that ignition delay at higher temperatures was shorter with the combustion duration being longer. The change in combustion phasing was found to be dependent on engine load. While the higher coolant temperature simplifies heat recovery from the coolant itself, the consequently higher exhaust gas temperatures observed means that the heat losses are moved more towards the exhaust where energy recovery is easier.
Singh, Vikram, Tunestal, Per, Tuner, Martin
Modeling of Phase Change within a Wax Element Thermostat Embedded in an Automotive Cooling System2017-01-01313/28/2017
In an automotive cooling circuit, the wax melting process determines the net and time history of the energy transfer between the engine and its environment. A numerical process that gives insight into the mixing process outside the wax chamber, the wax melting process inside the wax chamber, and the effect on the poppet valve displacement will be advantageous to both the engine and automotive system design. A fully three dimensional, transient, system level simulation of an inlet controlled thermostat inside an automotive cooling circuit is undertaken in this paper. A proprietary CFD algorithm, Simerics-Sys®/PumpLinx®, is used to solve this complex problem. A two-phase model is developed in PumpLinx® to simulate the wax melting process. The hysteresis effect of the wax melting process is also considered in the simulation. The physics captured in the simulation includes the turbulent flow out of the coolant pump, turbulent mixing, heat transport, and rigorous treatment of Fluid Structure Interaction (FSI) of the circuit with the dynamic valves in the system. Two different operating sets of data are used for the analysis, case A, lower engine speed and case B, higher engine speed. The details of the model setup and the comparisons of the simulation results with experimental data are discussed in the paper.
Srinivasan, Chiranth, Zhang, Chonglin, Gao, Haiyang, Wang, De Ming, Slike, Jody
Effects of Fuel Properties Associated with In-Cylinder Behavior on Particulate Number from a Direct Injection Gasoline Engine2017-01-10023/28/2017
The purpose of this work was to gain a fundamental understanding of which fuel property parameters are responsible for particulate emission characteristics, associated with key intermediate behavior in the engine cylinder such as the fuel film and insufficient mixing. Accordingly, engine tests were carried out using various fuels having different volatility and chemical compositions under different coolant temperature conditions. In addition, a fundamental spray and film visualization analysis was also conducted using a constant volume vessel, assuming the engine test conditions. As for the physical effects, the test results showed that a low volatility fuel displayed high particulate number (PN) emissions when the injection timing was advanced. The fundamental test clearly showed that the amount of fuel film on the impingement plate increased under such operating conditions with a low volatility fuel. Tests focusing on chemical effects with fuel blends having different aromatic and olefin contents were also conducted. The test results obtained under a completely vaporized condition showed that a test fuel with a high aromatic content displayed higher PN emissions under rich conditions than one with an increased olefin content. Based on all the test results, it was concluded that in-cylinder behavior, such as the fuel film and a rich mixture, plays an important role related to the effects of fuel properties on PN emissions. The results suggest it is imperative to take into account not only the fuel chemical impact, but also the fuel physical effects associated with key in-cylinder behavior in order to simulate engine-out particulate emissions accurately.
Tanaka, Daisuke, Uchida, Ryo, Noda, Toru, Kolbeck, Andreas, Henkel, Sebastian, Hardalupas, Yannis, Taylor, Alexander, Aradi, Allen
Heat Transfer Effect on Performance Map of a Turbocharger Turbine for Automotive Application2017-01-10363/28/2017
In the last few years, the effect of diabatic test conditions on compressor performance maps has been widely investigated leading some Authors to propose different correction models. The aim of the paper is to investigate the effect of heat transfer phenomena on the experimental definition of turbocharger maps, focusing on turbine performance. An experimental investigation on a small turbocharger for automotive application has been carried out and presented. The study focused onto the effects of internal heat transfer on turbine thermomechanical efficiency. The experimental campaign was developed considering the effect of different heat transfer state by varying turbine inlet temperature, oil and coolant temperature and compressor inlet pressure. An original model previously developed by the Authors is adopted for the correction of compressor steady flow maps. The major benefit of this method is represented by the easiness of data post-processing, the data base economy, the reduced number of geometrical and physical input parameters required and the accuracy of the solution. Besides, this model does not need an out-of-standard test bench to obtain the compressor maps. The corrected compressor results were then used to evaluate turbine thermomechanical efficiency, generally assessed on the basis of compressor power absorption.
Marelli, Silvia, Gandolfi, Simone, Capobianco, Massimo
A Research Study on a Curved Radiator Concept for Automotive Engine Cooling2017-01-06313/28/2017
The need to increase the fuel-efficiency of modern vehicles while lowering the emission footprint is a continuous driver in automotive design. This has given rise to the use of engines with smaller displacements and higher power outputs. Compared to past engine designs, this combination generates greater amounts of excess heat which must be removed to ensure the durability of the engine. This has resulted in an increase in the number and size of the heat exchangers required to adequately cool the engine. Further, the use of smaller, more aerodynamic front-end designs has reduced the area available in the engine compartment to mount the heat exchangers. This is an issue, since the reduced engine compartment space is increasingly incapable of supporting an enlarged rectangular radiator system. Thus, this situation demands an innovative solution to aid the design of radiator systems such that the weight is reduced while maintaining the engine within acceptable operating temperatures. One potential solution is a conformal radiator concept that can solve the engine cooling challenge through a packaging-based approach. This paper presents the results of a study that focused on factors such as radiator tube bend radius and bend angle, tool-tube clearance, and coolant temperature. A test matrix was created to study these factors using a Design of Experiments (DOE) methodology. Samples were created and tested using a purpose-designed bench test rig that measured pressure differences. Analysis of the DOE study confirmed that radiator tube bend angle, tool-tube clearance, and coolant temperature are key factors affecting the output pressure in the curved tubes that could be used in a future radiator concept. In conclusion, the evaluation of this first concept gives some promise to the possibility of a curved-tube automotive radiator and indicates the need for more complex research studies to be performed.
Ogbuaku, David C., Potter, Timothy, Boileau, James M.
Experimental Investigation of the Impact of Nanofluids on Heat Transfer Performance of a Motorcycle Radiator2017-01-16113/28/2017
In the present work, the effect of various nanofluids on automotive engine cooling was experimentally studied. Al2O3, TiC, SiC, MWNT (multi-walled nanotube), and SiO2 nanoparticles with average diameter ranging between 1 and 100 nm were mixed with distilled water to form nanofluids. An ultrasonic generator was used to generate uniform particle dispersion in the fluid. A compatibility test was carried out on all nanofluids and it was found that TiC, MWNT, and Si3N4 nanoparticles settled and separated from the fluid within 3 hours after preparation. The engine cooling performance testing setup consisted of an Aprilia SXV 450 engine, the nanofluid cooling loop, a radiator, a fan, etc. Thermocouples and resistance temperature detectors (RTD’s) were attached to the inlet and outlet of the radiator hose to monitor the temperature changes taking place in the cooling system. A flowmeter was attached to the inlet hose of the radiator to monitor the coolant flow rate. Results of heat transfer capability were compared for cooling system with and without nanoparticle seeding. It was observed that the heat dissipation capacity of nanofluids increased with increasing volume concentration of nanoparticles and also with increasing coolant flow rate. The results showed that the heat dissipated by TiO2, SiO2 and Al2O3 nanofluids were 31.9%, 27.7% and 12.5% higher than the base fluid, at 3.5 GPM flow rate and at 1% volume concentration of nanoparticles.
Mathivanan, Elankathiravan, Gasior, David, Liu, Liping, Yee, Kingman, Li, Yawen
Robust 1D Modelling for Automotive HVAC Warmup Prediction Using DFSS Approach2017-01-01793/28/2017
In an automotive air-conditioning (AC) system, the heater system plays a major role during winter condition to provide passenger comforts as well as to clear windshield defogging and defrost. In order to meet the customer satisfaction the heater system shall be tested physically in severe cold conditions to meet the objective performance in wind tunnel and also subjective performance in cold weather regions by conducting on road trials. This performance test is conducted in later stage of the program development, since the prototype or tooled up parts will not be available at initial program stage. The significance of conducting the virtual simulation is to predict the performance of the HVAC (Heating ventilating air-conditioning) system at early design stage. In this paper the development of 1D (One dimensional) model with floor duct systems and vehicle cabin model is studied to predict the performance. Analysis is carried out using commercial 1D simulation tool KULI®. All the simulation parameter which affects the correlation process has been studied carefully by using DFSS (Design for six sigma) methodology. L18 orthogonal array developed to understand the influence of each simulation parameters. Data analysis is carried out from DFSS study output and identified the importance of each simulation parameters which is being adjusted for correlation. This methodology helps to predicts accurately for any change in the HVAC heater systems circuit components like heater core, heater core inlet coolant flows, heater core inlet coolant temperatures, heater core airflow etc. This study enhances to reduce the number of physical tests, prototypes and cost involved in it.
Sambandan, Saravanan, Valencia, Manuel, S, Sathish Kumar
Comparison of Extended Life Coolant Corrosion Protection Performance2017-01-06273/28/2017
In this paper, new test results in the use of electrochemical techniques to measure corrosion in extended life engine coolants are presented. Corrosion protection performance of the engine coolants (including both fresh coolants and simulated used coolants) for typical cooling system metals under heat rejecting and heat accepting surface corrosion conditions for both general corrosion and localized corrosion are measured under conditions similar to the ones encountered in vehicle engine cooling systems as a function of immersion time. Fleet tests of the coolants were also conducted. They are used to provide support on the electrochemical test methodologies adopted. The effective use of electrochemical techniques to aid the development of the next generation of extended life coolant technologies with improved corrosion protection performance and a longer service life will be demonstrated and discussed.
Yang, Bo, Woyciesjes, Peter, Gershun, Aleksei
Single-Fluid-Pumped Radiators with Increased Turn-Down Ratio and Control in the Stagnation RegimeTBMG-265293/1/2017
Fluid-pumped radiators are used to reject heat from structures to space. A fluid travels inside the structure to collect heat, and then travels external to the structure through radiators where the heat is rejected to space via radiation heat transfer. A radiator is essentially several tubes attached to a thermally conducting plate or face sheet. The fluid cools as it travels along the inside of the tubes, and then returns to the inside of the structure to repeat the heat rejection cycle. If the structure contains humans, the fluid in the structure must be nontoxic and nonflammable. Further, as space can be extremely cold (4 K), the fluid external to the structure may freeze, particularly during low-power operations where heat rejection needs are minimal. Freezing of the fluid renders the radiator inoperable, and unfreezing a radiator can be very difficult, power-intensive (i.e. heaters), and/or timely. For these reasons, two fluids may be used: one inside that is compatible with humans (e.g. water), and one outside that has a low freezing point (e.g. ammonia). The heat is then transferred from the inner loop to the external loop through a heat exchanger. This dual-loop system is more complex and heavier than a single-loop system. However, as the outer loop does not freeze as easily, the dual-loop radiator system can be operated at lower heat rejection loads, increasing its overall heat rejection range (or turn-down ratio) over that of the single-loop system.
Application of Rapid Heat and Cool Molding to High Strength Outer Parts without Painting Treatment2016-32-002411/8/2016
Glass fiber reinforced plastic of polyamide is applied as one of the materials used for the high strength exterior parts of a motorcycle, such as a rear grab rail or a carrier, to which both strength and good exterior appearance are required. However, Glass Fiber reinforced Polypropylene (PPGF), which is relatively inexpensive material, has a property that the contained glass fibers are prone to be exposed at the surface and, therefore, the requirements for good appearance are hardly met by using PPGF. In this study, Heat and Cool molding method (H&C molding) was employed to realize a cost reduction by using PPGF yet without applying painting process, and the established method was applied to mass production while fulfilling the requirements for a good exterior appearance. In H&C molding, the metal molds are heated up by steam and cooled down by water after molding. This process works for making superior surface appearances and the appearance quality is determined by the temperature control of the molds. H&C molding has been generally applied to the parts with a flat shape and straight piping with a diameter of around 10 mm is arranged close to the surface of a metal mold cavity to get a good efficiency of temperature control. However, when this method is applied to a motorcycle part that is structured by three dimensional surfaces, these conventional piping arrangements cannot satisfy the requirements for a short molding cycle time and an even distribution of mold surface temperatures at the same time. In our study, a piping arrangement design by which the pipes are located along the three dimensional cavity surfaces was investigated. The piping arrangement design was determined based on the measurement results on test pieces and the molding cycle time of 100 seconds was eventually achieved. Furthermore, a proof testing to examine the material strength and the weather resistances is conducted as well.
Sugio, Daisuke, Okazaki, Shinpei, Kaneko, Mitsuo
Film Cooled SurfaceTBMG-2570211/1/2016
Turbine film cooling flows typically are subject to jet detachment and reduced cooling effectiveness for high blowing rates. Current concepts to improve jet attachment involve impractical or overly complex hole designs due to manufacturing or durability constraints. Novel film cooling concepts from NASA’s Glenn Research Center involve creating a V-shaped recess on the flow surface of a turbine blade to induce fluid, temperature, or shedding effects; threading turbine film cooling holes with helical channels or grooves (much like the threads of a screw) for the purpose of producing a swirling flow of cooling fluid exiting the film cooling hole; and pairing the threaded holes with holes that have an opposite direction of swirl.
Optical Investigations of Soot Formation Mechanisms and Possible Countermeasures on a Turbocharged Port Fuel Injection SI Engine2016-01-216310/17/2016
Despite the known benefits of direct injection (DI) spark ignition (SI) engines, port fuel injection (PFI) remains a highly relevant injection concept, especially for cost-sensitive market segments. Since particulate number (PN) emissions limits can be expected also for PFI SI engines in future emission legislations, it is necessary to understand the soot formation mechanisms and possible countermeasures. Several experimental studies demonstrated an advantage for PFI SI engines in terms of PN emissions compared to DI. In this paper an extended focus on higher engine loads for future test cycles or real driving emissions testing (RDE) is applied. The combination of operating parameter studies and optical analysis by high-speed video endoscopy on a four-cylinder turbocharged SI engine allows for a profound understanding of relevant soot formation mechanisms. For selected operating points, engine operating parameters such as injection timing, inclination of a charge motion flap, and engine coolant temperature were varied. Furthermore, the impact of two different spray layouts on the mixture formation was evaluated. Parameter sets showing significant reduction of PN emissions were subsequently analyzed using high-speed video endoscopy. Optical access to both the intake port as well as the combustion chamber allows visualization of fuel transport mechanisms leading to diffusion flames and soot emissions respectively. In summary, this study shows that port fuel injection at high engine loads can lead to significant PN emissions. Three locations within the combustion chamber could be identified as sources for diffusion flames leading to particulate emissions. The governing parameters allowing substantial reduction of PN emissions at these locations were found to be the injection timing and the charge motion.
Schueck, Claudius, Koch, Thomas, Samenfink, Wolfgang, Schuenemann, Erik, Tafel, Stephan, Towae, Oliver
Influence of Crankcase Oil Properties on Low-Speed Pre-Ignition Encountered in a Highly-Boosted Gasoline Direct Injection Engine2016-01-227010/17/2016
This paper reports an experimental investigation on the influence of the crankcase oil properties on the engine combustion in the low-speed pre-ignition (LSPI) zone. The investigation was conducted on a highly boosted 1.5L TGDI engine operated at the low-speed-end maximum torque, at which LSPI events were observed most frequently. Six different engine oils were tested, covering SAE 0W-20, 0W-30, 0W-40, 5W-20, 5W-30 and 5W-40. In order to evaluate the evaporative characteristics of the crankcase oil, for each of the selected engine oils, the tests were conducted at two different coolant temperatures, 90°C and 105°C. Because SAE 5W-30 was the base oil for the engine under study, for this particular oil, the investigation was extended to the impact of different levels of the mixture enrichment. Followings were found: 1) LSPI events were observed when the engine was operated with a stoichiometric mixture for all the oils tested. 2) No clear indication on which SAE oil tested had a stronger influence on LSPI than other oils, either promoting or inhibiting LSPI, because the influences on LSPI of the related oil properties might not be as strong as that of the high gasoline content in the oils, which reached about 6% in the tests. 3) Behavior of LSPI was random in all the tests and a particular LSPI pattern observed in a test was difficult to be reproduced under the same condition. This suggests that LSPI may be triggered at a complicated condition with contributions from many variable parameters. It may be meaningful to characterize the behavior of LSPI with a statistical approach.
Teng, Ho, Luo, Xuwei, Hu, Tingjun, Miao, Ruigang, Wu, Min, Chen, Bin, Zeng, Fanhua
Energy Saving Analysis of Vehicle Hydraulic Retarder Thermal Management System Based on Rankine Cycle2016-01-19419/18/2016
Vehicle hydraulic retarders are applied in heavy-duty trucks and buses as an auxiliary braking device. In traditional cooling systems of hydraulic retarders, the working fluid is introduced into the heat exchanger to transfer heat to the cooling liquid in circulation, whose heat is then dissipated by the engine cooling system. This prevents the waste heat of the working fluid from being used effectively. In hydraulic retarder cooling system based on the Organic Rankine Cycle, the organic working fluid first transfers heat with the hydraulic retarder working fluid in Rankine cycle, and then outputs power through expansion machine. It can both reduce heat load of the engine cooling system, and enhance thermal stability of the hydraulic retarder while recovering and utilizing braking energy. First of all, according to the target vehicle model, hydraulic retarder cooling system model based on Rankine cycle is established. Through presetting Rankine cycle parameters, characteristics and power consumption of this cooling system are analyzed under different hydraulic retarder working conditions. Then a mathematical model of traditional hydraulic retarder cooling system is set up. Its characteristics and power consumption under different hydraulic retarder working conditions are analyzed. Next, the effectiveness of the mathematical model of hydraulic retarder cooling system model based on Rankine cycle is verified by experiments. Finally, based on the Rankine cycle model after verification, two cooling systems are compared in cooling capacity, power consumption, economy and volume under the same circumstances. The results show that, in contrast to traditional cooling system of hydraulic retarder, hydraulic retarder cooling system based on the Organic Rankine Cycle, though taking up a little more space, can effectively reduce heat load of engine cooling system, improve thermal stability of hydraulic retarder, lower energy consumption and be more economical.
Wang, Tie, Tan, Gangfeng, Guo, Xuexun, Xiong, Shengguang, Zhang, Zhiwei, Gao, Xin
Lattice Structures Coating Concept for Efficient Thermal Linking BedsTBMG-251758/1/2016
Conventional air revitalization technology for removal of CO2, moisture, and trace organic contaminants usually involves a packed bed of sorbent pellets that can be regenerated using a concept similar to that of pressure swing adsorption (PSA). Additional heat input for thermal regeneration is preferred during the adsorption-desorption process to increase the regeneration efficiency. Typically, a pair of adsorber modules consisting of the same sorbent material with identical loading capacity is placed in parallel and work in tandem, where one module adsorbs the contaminants from the process air while the other is in regeneration mode. The two adsorber modules have separate housings and may be placed in separate locations.
Plastic Sheet, Polycarbonate, TransparentAMSP83310A (Current)7/12/2016
This specification covers transparent flat polycarbonate plastic sheet material suitable for aerospace transparent enclosures requiring excellent optical properties.
AMS P Polymeric Materials Committee
Optimization Solutions for Fan Shroud2016-01-13934/5/2016
Fan shroud is one of the critical components in an engine cooling system. It helps in achieving optimum air flow across the heat exchangers. The major challenge is to design a fan shroud which meets noise, vibration and harshness (NVH) requirements without compromising on air flow targets [1]. An improperly designed fan shroud will cause detrimental effects such as undesirable noise and vibration, which will further damage the surrounding components. In current days, multiple simulations and test iterations are carried out in order to optimize its design. The objective of this paper is to provide a design framework to achieve optimized fan shroud that meets NVH requirements in quick turnaround time using Design for Six Sigma (DFSS) approach [2]. The purpose of the Engine cooling system is to maintain the coolant temperature across the vehicle. Fan shroud accommodates the fan which in turn provides necessary air distribution across the radiator in order to have effective engine cooling. In this paper, DFSS approach is adopted to identify and optimize the factors which govern the NVH design of fan shroud. DFSS approach - nominal the best is used for this analysis which has an output, control factors and the noise factors. The modal frequency of the fan shroud is the output from the analysis and is evaluated in two modes, flexible mode and pumping mode. All the design parameters such as wall thickness, number of ribs, structural embossing which affects the output are considered as control factors. The under hood air temperature and the reduction in structural rigidity due to aging are considered as the noise factors. L18 Orthogonal experiment is used for this analysis, 18 design models are created in order to capture different combinations of control factor levels. Multiple control factors are examined to find out which would actually controls the designing of fan shroud in NVH perspective .Structural embossing and number of ribs for fan support are found to be the important design factors which contribute to better shroud NVH characteristics. A CFD simulation is also carried to check the airflow rate of the optimized design. The optimized design suggested in this paper had met both NVH and CFD targets. This study can be used further in order to reduce weight of the shroud and as best practice guidelines for future vehicles fan shroud designing which would ultimately reduce development time and cost.
Konikineni, Prabhakar, Sundaram, V., Sathish, Kumar, Thirukkotti, Sankarasubramanian
A DFSS Approach to Design Cooling System of Small Passenger Car Having Rear Engine and Front Mounted Radiator2016-01-06574/5/2016
DFSS is a disciplined problem prevention approach which helps in achieving the most optimum design solution and provides improved and cost effective quality products. This paper presents the implementation of DFSS method to design a distinctive cooling system where engine is mounted in the rear and radiator is mounted in the front of the car. In automobile design, a rear-engine design layout places the engine at the rear of the vehicle. This layout is mainly found in small, entry level cars and light commercial vehicles chosen for three reasons - packaging, traction, and ease of manufacturing. In conventional Passenger cars, a radiator is located close to the engine for simple packaging and efficient thermal management. This paper is about designing a distinctive cooling system of a car having rear mounted engine and front mounted radiator. This kind of arrangement requires lengthy coolant lines extended between the radiator and the engine throughout the length of the car, routed beneath the car. The U-shaped arrangement where radiator and engine are at higher coolant head and cooling lines are at very low coolant head becomes critical as air traps in the coolant system during coolant filling and de-aeration process. This restricts the coolant circulation during vehicle running-in and thus affect the life of critical components due to overheating. This paper also explains cooling system having external bypass instead of internal bypass to reduce overall cost and to provide simple and compact engine bypass circuit. The external bypass close to coolant pump offers a much lower resistance flow path as compared to the long radiator cooling lines increasing the risk of less coolant flows through the radiator as compared to bypass. These challenges were addressed using DFSS and DOE method. An optimum Design is finalized using DFSS approach and based on the analysis of the various tests carried out as per DOE. This design provide compact packaging of coolant system, ensure better thermal management and maintain good aesthetics of the automobile. The serviceability of the engine i.e. filling of the coolant and process of de-aeration is also simplified with the finalized design.
Sethuramalingam, T, Parmar, Chandrakant, Tiwari, Sashikant
A Novel Cooling System Control Strategy for Internal Combustion Engines2016-01-02264/5/2016
An innovative control strategy, which is based on the Robust Model Predictive Control (MPC) methodology, was developed with the purpose of optimizing the engine thermal management; the proposed control strategy adjusts the coolant flow rate by means of an electric pump, in order to bring the cooling system to operate around the onset of nucleate boiling. In the present paper, the advantages of the proposed cooling approach are evaluated along the NEDC homologation cycle, which was both simulated and replicated by means of laboratory tests; the latter include coolant, lubricant and wall temperature measurements. Special attention was reserved to the warm-up period. The case considered herein is that of a Spark Ignition engine, about 1.2 dm3 displacement, and a comparison with standard crankshaft driven pump is included. The proposed strategy makes use of a dynamic model of the cooling system of an ICE that is able to predict the heat transfer both under single-phase forced convection and in the presence of nucleate or saturated boiling. The model, which was widely validated by experimental tests, also defines a metrics for establishing the heat transfer mechanism inside the engine and for estimating the distance of the engine thermal state from the onset of nucleate boiling. Results show that the developed MPC algorithm is robust in terms of disturbance rejections, respects the defined system constraints and it is effective in decreasing the warm-up time and in reducing the coolant flow rate under fully warmed conditions as compared to the standard mechanical pump.
Castiglione, Teresa, Pizzonia, Francesco, Bova, Sergio
An Engine Thermal Management System Design for Military Ground Vehicle - Simultaneous Fan, Pump and Valve Control2016-01-03104/5/2016
The pursuit of greater fuel economy in internal combustion engines requires the optimization of all subsystems including thermal management. The reduction of cooling power required by the electromechanical coolant pump, radiator fan(s), and thermal valve demands real time control strategies. To maintain the engine temperature within prescribed limits for different operating conditions, the continual estimation of the heat removal needs and the synergistic operation of the cooling system components must be accomplished. The reductions in thermal management power consumption can be achieved by avoiding unnecessary overcooling efforts which are often accommodated by extreme thermostat valve positions. In this paper, an optimal nonlinear controller for a military M-ATV engine cooling system will be presented. The prescribed engine coolant temperature will be tracked while minimizing the pump, fan(s), and valve power usage. A case study investigates the proposed control strategy’s performance in comparison to other methods for temperature tracking and energy conservation. The optimal nonlinear controller offered satisfactory coolant temperature tracking with an average error of 0.35°C and at least 13% reduction in total cooling power.
Tao, Xinran, Wagner, John R.
Prediction of Engine Thermal Behavior during Emission Cycle Using 1D Four Point Mass Model2016-01-01974/5/2016
The traditional approach of engine thermal behavior of engine during startup has largely been dependent on experimental studies and high fidelity simulations like CFD. However, these techniques require considerable effort, cost and time. The low fidelity simulations validated with experimental results are becoming more popular due to their ease in handling the several parameters such as cost effectiveness and quick predictive results. A four point mass model of engine thermal behavior during cold start has been developed to study the engine warm up temperature behavior. The four point mass model considers the lumped mass of coolant, mass of engine directly associated with the coolant, mass of engine oil and mass of engine directly associated with the engine oil. The advantage of four point model is to predict the coolant temperature as well as lubricant temperature during the transient warm up cycle of the engine. The error between predicated temperatures and experimental are within 10%.
Ranjan, Ravi, Jha, Kaushal Kumar, Brahmasani, Lakshmaiah, Khan, Parvej
Cold-Ambient Warm-Up Predictions: A Novel Approach Using 1D Computational Models2016-01-01984/5/2016
Vehicle development teams find it challenging to predict what their Heating, Ventilation and Air-Conditioning (HVAC) module performance will be for cold ambient (∼ -20 deg. C) test cycles such as defrost and cabin warm-up before the car is built. This uncertainty in predictions comes from varying engine heat rejection to coolant due to cold cylinder wall temperatures, calibration changes and degraded performance of various components within the cooling system such as the coolant pump owing to higher viscosity of the coolant. Measuring engine heat rejection at cold ambient is extremely difficult as the engine warms up as soon as it is fired. Multiple measurement points require long lead time to soak to the cold target temperature. It is a common practice to adjust engine calibration parameters to warm up coolant as fast as possible for an adequate defrost and cabin warm-up performance. A computational model can really help quantify the effect of each of the key parameters to enable the HVAC engineer to achieve the target performance most efficiently. In view of this, a novel approach is proposed to simulate and improve cold ambient warm-up predictions using one-dimensional (1D) computational models. Initially an engine thermodynamic model was developed and validated for a 2L gasoline turbocharged direct injection engine using commercial code Ricardo WAVE®. This model was used to predict cold ambient engine heat rejection and quantify the effect of each of the calibration parameters such as spark timing, air-fuel ratio, manifold pressure and cylinder wall temperature. The modified engine heat rejection was then applied to a cooling system, developed in Flowmaster® where the effects of the engine and coolant thermal inertia and component performance degradation were taken into account to quantify the final effect of various key parameters on cabin air temperature. It was observed that proposed approach would reduce testing cost by guiding the testing process into targeted tests to achieve desired cold warm-up capability efficiently.
Uppuluri, Sudhi, R. Khalane, Hemant, Umbarkar, Yogesh, Naiknaware, Ajay
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