For spacecraft with high power consumption, it is reasonable to build the thermal control system based on a two-phase mechanically pumped loop. The heat-controlled accumulator is a key element of the two-phase mechanically pumped loop, which allows for the control of pressure in the loop and maintains the required level of coolant boiling temperature or cavitation margin at the pump inlet. There can be two critical modes of loop operation where the ability to control pressure will be lost. The first critical mode occurs when the accumulator fills with liquid at high heat loads. The second critical mode occurs when the accumulator is at low heat loads and partial loss of coolant, for example, due to the leak caused by micrometeorite breakdown. Both modes are caused by insufficient accumulator volume or working fluid charge. To analyze the loop characteristics in critical modes, experiments were conducted on a test bench with ammonia coolant, and a mathematical simulation of a two-phase

Hodunov, Artem, Gorbenko, Gennadiy, Turna, Rustem, Koval, Polina

Design and Development of a Novel Air Cycle Refrigeration System for Passenger Vehicles

2022-28-044711/09/2022

Current AC system use hydrofluorocarbons (HFC) as refrigerant to transfer heat from cabin and cool the passengers. However, most refrigerants used today have severe environmental effects due to high global warming potential leading to global warming effects. Montreal Protocol and Kigali amendment calls for all nations to reduce refrigerant usage and transport sector being one of the main consumer of refrigerant, regulations regarding refrigerant usage and emission are becoming more stringent day by day. In this paper, a novel air cycle refrigeration system has been designed and also tested for passenger vehicle applications. Currently used refrigerant R134a with high GWP of 1400+ in mobile air conditioning system is completely eliminated in the air refrigeration system. The aim is to achieve a passenger comfort using air as heat transfer medium and power input either from the engine exhaust air of an ICE vehicle or a secondary air compressor. The effect of performance of various

Gupta, Rajat, Arora, Maneesh, Mohite, Yashwant, Ghate, Pravin, CHIGULLAPALLI, ANIL KUMAR, Maurya, Anurag

Numerical Modelling of Coolant Filling and De-aeration in a Battery Electric Vehicle Cooling System

2022-01-093703/29/2022

Trapped air bubbles inside coolant systems have adverse effect on the cooling performance. Hence, it is imperative to ensure an effective filling and de-aeration of the coolant system in order to have less air left before the operation of the coolant system. In the present work, a coolant/air multiphase VOF method was utilized using the commercial CFD software SimericsMP+® to study the coolant filling and subsequent de-aeration process in a battery electric vehicle (BEV) cooling system. First, validations of the numerical simulations against experiment were performed for a simplified coolant recirculation system. This system uses a tequila bottle for de-aeration and the validations were performed for different coolant flow rates to examine the de-aeration efficiency. A similar trend of de-aeration was captured between simulation and experimental measurement. Next, the same numerical techniques were further applied to a BEV cooling system to evaluate the efficiency of de-aeration

Tao, Mingyuan, Slike, Jody, Bhagat, Meghraj, Srinivasan, Chiranth, Zhang, Yi, Motin, Abdul

Proposed Standards And Methods For Leak Testing Lithium-Ion Battery Packs Using Glycol-based Coolant With Empirically Derived Rejection Limits

2022-01-084803/29/2022

Lithium-ion batteries are a highly suitable energy source for many applications, particularly in the automotive sector due to their high energy density and low self-discharge rate. During the production of battery cells, rapid detection of leaks is essential to achieve necessary lifetime service-life and safety requirements. Once assembled into packs, whether made of prismatic, cylindrical or pouch cells, packs must be cooled by common automotive thermal management systems, for example those employing engine coolant and radiator, and in which manufacturers must prevent various leak-producing defects that affect durability, longevity and safety Two types of cooling systems are used in automobiles, an active variant in which refrigerant, compressor, evaporator and heat exchanger are used to operate the air conditioning system, or a passive variant with a cooling medium, typically a water/glycol mixture, and a heat exchanger cooled by ambient air. While good industry standards are

Wetzig, Daniel, Blaufuß, Marc

Experimental investigation of thermal safety of the IC engine in the event of coolant loss

2021-28-015210/01/2021

Power density (power/engine cubic capacity) of the latest passenger car Diesel and Gasoline engine keeps increasing with a focus to deliver best in class performance along with meeting CAFE and emission norms. This increase in power density increases the thermal load onto the coolant system. Coolant temperature sensor monitoring the coolant temperature, proper radiator sizing, optimum water pump flow capacity and thermostat tuned to the required coolant temperature range are the typical measures taken to ensure safe operation of the engine and avoid any over-heating. Typical cooling system failures are mostly due to low coolant level, a defective thermostat, non-operative water pump & fan and blockage in the coolant circuit, etc. Most of these failures can be detected with the help of coolant temperature sensor and pre-emptive measures can be taken to avoid engine loss. However, in the event of complete loss of coolant in the engine, the coolant temperature sensor will become

Sithick basha, Abubakker, NAMANI, Prasad, Sebastian, Ranjit George, Malekar, Amit, Vellandi, Vikraman

3D CFD coolant system simulation for a full vehicle drive-cycle

2021-26-040709/22/2021

The present work deals with the 3-D, transient, system level CFD simulation of automotive coolant system, which includes actual CAD of radiator, cooling jacket, coolant pump, bypass valve and thermostat valve, using a 3D CFD solver Simerics MP+®. This work is in continuation of the work done by Srinivasan et al. (2017) where wax melting, conjugate heat transfer, Fluid Structure Interaction of the valve had been solved. Thermostat valve was controlled by wax phase change model which incorporates the hysteresis effect of wax melting and solidification. The current model will also include rigorous treatment of cavitation to account for the presence of dissolved gases and vaporization of the liquid coolant. The previous work dealt with simulation of opening and closing cycle of the thermostat/by-pass valve system. A methodology has been developed and implemented where the run-time of such a system has been made considerably faster enabling us to simulate complete drive cycle tests. The

Varshney, Mehul, Ballani, Abhishek, Pasunurthi, Shyam Sundar, Maiti, Dipak, Srinivasan, Chiranth

Case Study on Optimized Cooling System Concept for Electric Compact-SUV with Indian Environmental Conditions

2021-26-041009/22/2021

With the rising emission level in Indian cities, the focus on pure battery electric vehicle is increasing also in India. The Government of India his also focusing on preparing right policies like FAME-2 to promote the acceptability of EV's by providing subsidies as well as creating the required infrastructure. The environmental conditions in India is much different than other developed countries of Euro, China etc. The max. temperatures in India can go up to 55℃ in the hottest summer time, while during winters temperature can go up to <-25℃ in the northern Himalia region. In these conditions the cooling system of the electric-powertrain components like E-Machine Battery pack etc have to be protected for worst case scenarios specific to Indian conditions. Major cost driver of EV's lie in the HV battery packs and it is very important for acceptability of EV's that the Battery is maximized. With fast discharging and charging phenomena of battery pack required in automotive application can

Emran, M.Sc. Ashraf, Garg, Shivam, Manns, M.Sc. Patrick, Sharma, Vijay

Design Improvement and Failure Simulation of Thermostat Vent using Fatigue Test method

2021-26-045609/22/2021

Currently the Automotive industry demands highly competitive product to survive in the global tough competition. Even if there is a slight reduction in product cost and time has a high significant impact on business. Engineers are under tremendous pressure to develop competitive and give better product resolution at the earliest. The paper focuses on the thermostat, that is placed between the engine and the radiator. The thermostat has a function is to block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the Radiator. Once the engine reaches its operating temperature (In our case, SOT 88°C to FOT 98° C), the thermostat opens. The thermostat helps to warm-up the engine coolant quickly and thus the thermostat reduces engine wear, and emissions. The thermostat mechanism consist of cylinder is filled with a wax that begins to melt at designed SOT. A rod connected to the valve presses into this wax. When the wax melts

Solomon, Samson, Senniappan, Moorthy, Thiyagarajan, Rajesh, Ramakrishnan, Dakshinamoorthy, Rahim, Abdul

Innovative Control and Monitoring Algorithms and Strategies Based on Judicious Functional Partitioning and Frugal Engineering Concepts

2021-01-0124

04/06/2021

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

Assessment of In-Cylinder Thermal Barrier Coatings over a Full Vehicle Drive Cycle

2021-01-045604/06/2021

In-cylinder thermal barrier coatings (TBCs) have the capability to reduce fuel consumption by reducing wall heat transfer and to increase exhaust enthalpy. Low thermal conductivity, low volumetric heat capacity thermal barrier coatings tend to reduce the gas-wall temperature difference, the driving potential for heat transfer from the gas to the combustion chamber surfaces. This paper presents a coupling between an analytical methodology for multi-layer coated wall surface temperature prediction with a fully calibrated production model in a commercial system-level simulation software package (GT-Power). The wall surface temperature at each time step was calculated efficiently by convolving the engine wall response function with the time-varying surface boundary condition, i. e., in-cylinder heat flux and coolant temperature. This tool allows the wall to be treated either as spatially uniform with one set of properties, or with independent head/piston/liner components. Steady state

Koutsakis, George, Miles, Scott, Ghandhi, Jaal

Getting to the ‘Core’ of AV Thermal Management

20AVEP11_0511/01/2020

Data-gobbling processors require new cooling solutions - and the AV industry needs standards, says a veteran engineer. The universal understanding of autonomous vehicle safety is one of the most critical keys to broad adoption of self-driving technology. For AVs, what is “safe enough?” This understanding predicates the complement of sensors on the vehicle, which dictates the software and compute requirements, which allows for commoditization of the hardware. It's a domino effect. Quantifying or qualifying what is a “safe” autonomous platform requires industry-wide standards. When they are established, the rest will follow: sensor package requirements, computing requirements, commoditized hardware. Finally there is the real opportunity - the economization of AV manufacturing.

Shaw, Jim

The Use of CuO Nanoparticles as Additive to the Engine Coolant

2020-01-223609/15/2020

Cooling is one of the most important processes conditioning proper operation of combustion engines. The development of the higher-power engines entails greater thermal loads, in which in turn require an increased cooling. The use of nanofluids (NFs) with admixture of metallic or nonmetallic nanoparticles (NPs) promises a potential platform for miniaturization of heat exchangers and/or lower energy consumption. This is attributed to an extended surface area related to NPs in the fluid, which allows for increase of thermal conductivity and a considerable increase of the heat transfer coefficient of the fluid with NPs. Their thermo-physical properties, such as particle size, stability, viscosity, dispersion, heat dissipation efficiency, zeta potential and thermal conductivity and also their behavior under different amount in the base fluid are systematically investigated from the point of view of the choice of the best candidate for coolant applied in modern engines. The CuO NPs turn out

Siczek, Krzysztof, Wozniak, Marek, Rylski, Adam

The Numerical Study on the Effect of CuO Nanoparticle Additive into SI Engine Coolant on the Engine Power

2020-01-203209/15/2020

The goal of the study was to investigate the effect of different amounts of the CuO nanoparticles used as additive in the coolant on the power and efficiency of the analyzed SI engine. The temperature gradients in the engine body and its components were obtained using the elaborated model of the heat exchange in engine cooled with different fluids. The simplified model of combustion was used to estimate the temperature and power values generated during the combustion process in the engine under given load and speed values. The efficiency of the engine was estimated using the model taking into account various resistances generated during the operation of a given type of engine. The obtained changes in the engine power and efficiency resulted from the changed composition of the engine coolant were presented.

Siczek, Krzysztof, Wozniak, Marek, Diaconu, Mihai, Dima, Georgiana, Ion, Luiza, Bica, Ionela

Combustion Stability Study with Low Cetane Number Diesel and Biodiesel with 2-EHN Addition under LTC Conditions during Cold/Warm Start and Steady State Conditions

2020-01-206309/15/2020

A single cylinder Diesel engine was used to study combustion stability changes from a cetane number improver: 2-EHN. It has been added to a low cetane number diesel and two biodiesels blends with 20 % of SME or RME. All fuels have been raised to a CN of 51 with 2-EHN. Those fuels have been compared to a reference diesel with a CN of 55. Cold and warm start have been recreated for measurements at three conditions: cranking, engine speed increase and idle. Engine coolant temperature has been set to 20°C and 80°C for cold and warm start respectively. 2-EHN effects on combustion stability have been monitored through the IMEP covariance. Under cold-start, only the low cetane number diesel showed combustion stabilities improvements with 2-EHN addition. Moreover, the combustion stability was better than the reference diesel and the heat release rate show an enhancement of the cold flame. On the contrary, the biodiesel fuels exhibited higher IMEP covariances. Under warm start, all fuels

Oung, Richard, Foucher, Fabrice, Morin, Anne-Gaëlle

Design and Analysis of Modified Radiator Fins to Improve Overall Cooling Efficiency

2020-01-202909/15/2020

Internal Combustion engines have been a significant component of the industrial development in the 20th and 21st centuries. However, the high working temperatures cause extensive wear and tear among the parts and results in a loss in fuel efficiency and ultimately seize the engine. To prevent this, there was a need for a cooling system. The current systems cool the vehicle's engine by transferring heat from the engine to the coolant/water in the water jacket from where it reaches the radiator via tubes, and the hot temperature coolant is cooled. This article proposes a change in the design of radiator fins to improve the overall cooling efficiency of such systems. As radiator fins are instrumental in the heat transfer process, a design change in them results in substantial changes in the output efficiency results. The central concept that is utilized is to increase the surface area of the fins, which would increase the rate of heat loss from the pipes. This increase in surface area of

Mittal, Ankit, Misra, Ashwin, Sharma, Ayush, Gupta, Animesh, Ansari, Naushad

Disposable Device Treats Severe Side-Effect of Cancer

TBMG-3691205/01/2020

BrainCool AB, a Swedish medical device company that specializes in medical cooling technology for therapeutic hypothermia (brain cooling) and oncology, has completed patient recruitment in the Scandinavian multi-center pivotal trial of 180 patients to investigate its Cooral® System for prevention of oral mucositis (OM), one of the most debilitating side-effects of both standard and high-dose chemotherapeutic oncology treatments.

System Provides Cooling with No Electricity

TBMG-3682705/01/2020

A device was developed that can sit outside under blazing sunlight on a clear day without using any power to cool things down by more than 23 °F (13 °C). The device, which has no moving parts, works by a process called radiative cooling. It blocks incoming sunlight to keep from heating it up, and at the same time, efficiently radiates infrared light — which is essentially heat — that passes straight out into the sky and into space, cooling the device significantly below the ambient air temperature.

3-Dimensional Numerical Simulation on CuO Nanofluids as Heat Transfer Medium for Diesel Engine Cooling System

2020-01-110904/14/2020

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

Yang, Shuai, Yang, Xiaolin, Liu, Haifeng, Li, Xiuyuan

Experimental Analysis of a Multiple Radiator Cooling System with Computer Controlled Flow Rates

2020-01-094404/14/2020

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

Syed, Zaker, Wagner, John

Utilization of bench testing in vehicle thermal system development for extreme cold ambient condition

2020-01-139004/14/2020

Automotive thermal systems are becoming complicated each year. The powertrain efficiency improvement initiatives are driving transmission and engine oil heaters into coolant network design alternatives. The initiatives of electrified and autonomous vehicles are making coolant networks even more complex. The coolant networks these days have many heat exchangers, electric water pumps and valves, apart from typical radiators, thermostat and heater core. Some of these heat exchangers including cabin heaters deal with very small amount of coolant flow rates at different ambient conditions. This paper describes how viscosity can be a major reason for simulation inaccuracy, and how to deal with it for each component in the coolant network. Both experimental and computational aspects have been considered in this paper with wide range of ambient temperatures. Methods have been proposed to handle these issues in the simulation phase at the early phase of automotive thermal system development

Khandaker, Masuma, Uddin, Ahmed, Sanikal, Vijay, Fuad, Kaji, Lindquist, Craig, Baker, Gary, Rahman, Sadek

Off-Road Self-Propelled Work Machines Operator Enclosure Environment Part 1: Terms and Definitions

J3078/1_202001 (Current)01/29/2020

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 Radiator

2019-28-238111/21/2019

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

Bhargava, Aashish, Soni, Gaurav, Warkhade, Tushar

Miniature Stretchable Pump

TBMG-3529610/01/2019

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 Chips

TBMG-3459506/01/2019

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.

An Experimental Study of the Effects of Coolant Temperature on Particle Emissions from a Dual Injection Gasoline Engine

2019-01-005101/15/2019

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

Xia, Chun, Chen, Wenhao, Fang, Junhua, Huang, Zhen

Application of Electrically Driven Coolant Pumps on a Heavy-Duty Diesel Engine

2019-01-007401/15/2019

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

Granitz, Christina, Ratzinger, Josef, Eichlseder, Helmut, Surace, Alfonso

Reliability Case Analysis of an Autonomous Air Cooling System (AACS) for Aerospace Applications

2018-01-191610/30/2018

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

Fong, Chung Man, Norman, Patrick, Seki, Naoki

Variation in System Performance while Sorting DEF Heating Hardware Options

2018-01-181309/10/2018

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

Vermiglio, Ezio, Gilliam, Kyle, Chin, Anthony, Leonard, Treaver, Erickson, Darren

Taming the Thermal Behavior of Solid-State Military Lasers

TBMG-2908206/01/2018

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.

An Experimental Study on the Knock Mitigation Effect of Coolant and Thermal Boundary Temperatures in Spark Ignited Engines

2018-01-021304/03/2018

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

Cho, Seokwon, Song, Chiheon, Oh, Sechul, Min, Kyoungdoug, Ha, Kyoung-Pyo, Kim, Back-Sik

System-Level Investigation of Traction Inverter High-Temperature Operation

2018-01-046404/03/2018

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

Lu, Xi, Xiao, Kewei, Lei, Guangyin, Chen, Chingchi

Parallel Thermal Management System of the Water Medium Retarder

2018-01-077704/03/2018

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

Gao, Xin, Lei, Yulong, Chen, Wei, Cui, Guokai, Zhong, Lei

Development of Parallel and Direct Cooling System for EV/FCEV Inverter

2018-01-045404/03/2018

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

Seo, Heung Seok, Shin, Dongmin

A Model Predictive Approach to Avoid Coolant After-Boiling in ICE

2018-01-077904/03/2018

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

Castiglione, Teresa, Morrone, Pietropaolo, Bova, Sergio

System Characteristics of Direct and Secondary Loop Heat Pump for Electrical Vehicles

2018-01-0063

04/03/2018

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

Wang, Dandong, Gao, Tianyuan, Li, Wanyong, Yang, Yun, Shi, Junye, Chen, Jiangping

Thermodynamic Cycle and Working Fluid Selection for Waste Heat Recovery in a Heavy Duty Diesel Engine

2018-01-137104/03/2018

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

Rijpkema, Jelmer, Andersson, Sven, Munch, Karin

Effect of Thermal Management on Engine Performance

2018-01-022404/03/2018

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

Rajkumar, M., Vojtech, Ryan, Cigler, James

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