Browse Topic: Radiators

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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
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
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
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
Numerical Simulation of a 2018 F1 Car Cooling System for Silverstone Circuit2018-01-01694/3/2018
The thermal management of a Formula 1 car is a challenging task as it involves multiple components, systems and multiple sources of thermal energy. The present work attempts to model a representative F1 car following 2018 F1 regulations directly linked to the cooling systems requirements and performance. The main purpose of this work is to simulate the steady and transient behaviour of the cooling system when the vehicle is in a qualifying lap, and during the entire race, including the wait in the starting grid and the pit stops. This model includes the sub-models representing internal combustion engine, hybrid powertrain, vehicle, driver and an appropriate cooling system composed of radiators, pumps and expansion tanks. This work validates the cooling system of a representative 2018 F1 car for the Silverstone Circuit. This model is capable of simulating the overall thermal performance of the F1 car for sizing the cooling system for most of the F1 circuits. This paper presents a systematic approach followed for modelling a representative F1 car based on 2018 regulations, methods used for deriving appropriate data from various sources, approach used for validating the model and finally the strengths of the validated model for sizing the cooling system.
Tizon Otero, Victor, Samuel, Stephen
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
Fan Noise Prediction for Off-Highway Vehicle2017-01-18346/5/2017
Fan noise can form a significant part of the vehicle noise signature and needs hence to be optimized in view of exterior noise and operator exposure. Putting together unsteady CFD simulation with acoustic FEM modeling, tonal and broadband fan noise can be accurately predicted, accounting for the sound propagation through engine compartment and vehicle frame structure. This paper focuses on method development and validation in view of the practical vehicle design process. In a step by-step approach, the model has been validated against a dedicated test-set-up, so that good accuracy of operational fan noise prediction could be achieved. Main focus was on the acoustic transfer through the engine compartment. The equivalent acoustic transfer through radiators/heat exchangers is modeled based on separate detailed acoustic models. The updating process revealed the sensitivity of various components in the engine compartment. Unsteady CFD included the build-up of a sliding mesh model which was analyzed using the DDES method. After convergence, time data of blade surface pressure were exported in CGNS format. These pressure data were used to generate rotating dipole sources in acoustic FE analysis and predict the fan noise response in frequency domain at two selected rpm. Post processing includes the predicted noise at target microphone positions as well as colormaps of sound pressure distributions that can guide to the development of countermeasures.
von Werne, Dirk, Chaduvula, Prasanna, Stahl, Patrick, Jordan, Michael, Huber, Jamison, Kucukcoskun, Korcan, Niculescu, Mircea
Calibration and Demonstration of Vehicle Powertrain Thermal Management Using Model Predictive Control2017-01-01303/28/2017
Control of vehicle powertrain thermal management systems is becoming more challenging as the number of components is growing, and as a result, advanced control methods are being investigated. Model predictive control (MPC) is particularly interesting in this application because it provides a suitable framework to manage actuator and temperature constraints, and can potentially leverage preview information if available in the future. In previous SAE publications (2015-01-0336 and 2016-01-0215), a robust MPC control formulation was proposed, and both simulation and powertrain thermal lab test results were provided. In this work, we discuss the controller deployment in a vehicle; where controller validation is done through road driving and on a wind tunnel chassis dynamometer. This paper discusses challenges of linear MPC implementation related to nonlinearities in this over-actuated thermal system. Specifically, the fan and grill shutter actuators have a nonlinear influence on the individual airflows through the charge air cooler and radiator heat exchangers, and the design choices in dealing with these nonlinearities affects the control performance and controller memory requirements. The memory requirements of the resulting controller are also analyzed and compared to other MPC controllers.
Bonkoski, Phillip, Karnik, Amey Y., Fuxman, Adrian
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.
Effect of Engine Motion on the Fatigue Life of Cooling Components2017-01-03373/28/2017
Ensuring durability is one of the key requirements while developing cooling modules for various powertrains. Typically, road surface induced loads are the main driving force behind mechanical failures. While developing the components, road load accelerations are utilized in CAE simulations to predict the high-stress regions and estimate the fatigue life of the components mounted on the body. In certain scenarios where components are mounted to the body and attached to the engine with hoses, the components can experience additional loads associated with engine vibration. This attachment scheme requires a different analysis methodology to determine fatigue life. In the proposed paper, we look at the effect of engine motion (EM) on the fatigue life of internal transmission oil cooler (ITOC) which is mounted on the body through radiator and is simultaneously connected to the engine using a steel pipe. We propose a new CAE methodology taking into account the engine motion displacements.
Nadella, Kalyan S., Zhang, Yi
The Aerodynamic Development of the New Audi Q52017-01-15223/28/2017
The aerodynamic development of the new Audi Q5 (released in 2017) is described. In the course of the optimization process a number of different tools has been applied depending on the chronological progress in the project. During the early design phase, wind tunnel experiments at 1:4 scale were performed accompanied by transient DES and stationary adjoint simulations. At this stage the model contained a detailed underbody but no detailed engine bay for underhood flow. Later, a full scale Q5 model was built up for the aerodynamic optimization in the 1:1 wind tunnel at Audi AG. The model featured a detailed underbody and engine bay including original parts for radiators, engine, axles and brakes from similar vehicles. Also the 1:1 experiments were accompanied by transient DES and stationary adjoint simulations in order to predict optimization potential and to better understand the governing flow. The strong coupling of experimental and numerical tools enabled a best-in-class drag coefficient to be achieved not only for a single optimized vehicle setup but for the majority of four cylinder diesel and gasoline engines in base configuration even in SUV ground clearance (as required for LDT). This is not only true if the vehicle is equipped with the aerodynamically optimized “aero wheel” but also a number of optional rim designs allow comparably low drag values. In order to reach such low aerodynamic drag values, a variety of design and technical measures were necessary. A description of their definition and function is subject of the present paper.
Blacha, Thomas, Islam, Moni
Force Based Measurement Method for Cooling Flow Quantification2017-01-15203/28/2017
Quantification of heat exchanger performance in its operative environment is in many engineering applications an essential task, and the air flow rate through the heat exchanger core is an important optimizing parameter. This paper explores an alternative method for quantifying the air flow rate through compact heat exchangers positioned in the underhood of a passenger car. Unlike conventional methods, typically relying on measurements of direct flow characteristics at discrete probe locations, the proposed method is based on the use of load-cells for direct measurement of the total force acting on the heat exchanger. The air flow rate is then calculated from the force measurement. A direct comparison with a conventional pressure based method is presented as both methods are applied on a passenger car’s radiator tested in a full scale wind tunnel using six different grill configurations. The measured air flow rates are presented and discussed over a wide range of test velocities. The advantages and draw backs of both approaches are compared and discussed in detail. The proposed method is non-intrusive, leaving the heat exchanger core intact, with no need for integration of measurement points over the core region. Due to the measuring principle, the load-cell method will inherently over-predict the air-flow rate. This error is quantified and an empirical correction function is investigated. This paper shows that the corrected force based method determines the air flow rate through a heat exchanger with an accuracy similar to that of traditional pressure/velocity methods while offering a considerable number of advantages.
Hobeika, Teddy, Gullberg, Peter, Sebben, Simone, Lofdahl, Lennart
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
Thermal Protection of Rear Mounted Engine and Its Components Using a Ventilation Fan with Unique Monitoring and Fault Diagnosis Technique2017-01-06203/28/2017
The engine compartment of passenger car application contains various source which radiates the produced heat and raises the temperature level of the compartment. The rise in compartment temperature increases the body temperature of individual component. The rise in body temperature of critical components can endanger the durability or functionality of the specific component or a system in which it operates. The aim of this paper is to strategize thermal protection of the rear mounted engine and its components of a vehicle having radiator and cooling fan mounted in front. An additional ventilation fan with speed sensor is fitted alongside rear mounted engine and a unique monitoring technique framed in the EMS ECU to protect critical components like HT cables, alternators, ECUs, wiring harness etc. from thermal damage. The EMS continuously monitors the engine speed, vehicle speed and the PWM signal of ventilation fan to ensure the intended operation of the ventilation fan. With the implementation of additional ventilation fan it is observed that maximum engine compartment temperature does not exceed safe operating temperature limit when the vehicle is driven in all road load condition (including highway, city & gradient drive conditions) and in all vehicle operating conditions. Excessive operation at higher compartment temperature unnecessarily causes individual component durability & performance to deteriorate at considerably faster rate. Thus, method of the present disclosure ensures that every component in engine compartment is operating in safe operating limits. In-case any failure occurs in the ventilation fan, newly developed EMS diagnosis strategy identify fault and indicates the problem to the driver through telltale. EMS also restricts the vehicle speed to safely maneuver vehicle to the nearest service center for repair.
Parmar, Chandrakant, Tyagarajan, Sethuramalingam, Tiwari, Sashikant, Thonge, Ravindra, Paul, S Arun
A Numerical Study of Radiator Performance under a Transient Thermal Cycle2017-01-06233/28/2017
Radiator thermal cycle test is a test method to check out the robustness of a radiator. During the test, the radiator is going through transient cycles that include high and low temperature spikes. These spikes could lead to component failure and transient temperature map is the key to predict high thermal strain and failure locations. In this investigation, an accurate and efficient way of building a numerical model to simulate the transient thermal performance of the radiator is introduced. A good correlation with physical test result is observed on temperature values at various locations.
Wang, Zun, Zhang, Yi, lenormand, Christophe, Ansari, Mohammed, Henner, Manuel
Design of an Automatic Drag Reduction System Focusing on Cooling for Formula SAE Vehicle2016-36-051110/25/2016
The drag reduction system, commonly used in Formula 1, has as task to reduce the drag force that acts in the vehicle’s airfoils, increasing considerably its speed. When it comes to Formula SAE competition, since the speeds are lower than in F1, the purpose of the DRS can easily become the cooling, despite its name. This paper comes to the development of a drag reduction system applied to the frontal wing whose major objective is to increase the mass flow rate of air through the radiator. Based on a preliminary work supported by computational fluid dynamics, a frontal wing DRS can increase the mass flow rate in approximately 65% at an average velocity of 12 meters per second, which allows the team to use a smaller and lightweight radiator. The challenge was to design a lightweight and reliable automatic system, since it cannot fail nor take away the driver’s attention. To avoid these problems, an electric circuit was developed to control the actuators using the throttle position sensor data and lateral acceleration from an accelerometer.
Schinestzki, Wilcker Neuwald, Schreiner, Daniel Gustavo, Falcão, Carlos Eduardo Guex
Fan-shroud optimization for enhanced thermal performance16OFHP10_0610/1/2016
CFD helps researchers from Argonne, Cummins and CD-Adapco to maximize cooling air mass flow rates through heat exchangers. Tighter emissions requirements and underhood packing due to higher power demands from engines necessitate more optimized cooling packages. Fan and fan-shroud design is crucial for underhood airflow management. Fan shrouds funnel cooling air, which is sucked by the fan and passed through heat exchangers. Shroud design affects both the airflow and the noise generated by the fan. The vehicle underhood compartment consists of the engine and cooling package. In heavy-duty trucks, the cooling package includes the heat exchanger, fan shroud and fan. To optimize the fan-shroud shape to maximize cooling air mass flow rates through the heat exchangers, researchers from Argonne National Laboratory, Cummins and CD-Adapco used the Adjoint approach to optimization. Adjoint optimization is an efficient sensitivity analysis method for aerodynamic shape and pressure drop evaluation.
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
Simultaneous Improvement of Vehicle Under-Hood Airflow and Cooling Drag Using 3D CFD Simulation2016-01-02004/5/2016
The radiator is the key component of a vehicle’s cooling system. The cooling effectiveness of a radiator largely depends on the flow of fresh air through it. Thus, at high vehicle speeds, the mass flow rate and flow-distribution or flow-uniformity over the radiator surface are the major operating parameters influencing the performance of a radiator. Additionally, the mass of air coming from the front grille plays an important role on the total drag of the vehicle. This paper presents computational studies aiming at improving simultaneously the efficiency of a radiator and reducing the total drag of the vehicle; this is achieved using passive aerodynamic devices that alter the flow pattern approaching the radiator. The vehicle model considered is a Hyundai Veloster and all analyses were carried out using a commercial CFD code Star-CCM+ version 10.04 by CD-adapco. The baseline model used in this study has a vertical radiator with no air-duct where most of the incoming air from the grille blows over the bottom part of the radiator, which makes the upper part of the radiator ineffective. An air-duct introduced between the front grille and the radiator helps the airflow uniformity over the radiator surface by directing the flow towards the upper part of the radiator. This also resulted in an increased mass flow through the radiator due to faster flow induced by the air-duct. Since only the airflow going through the air-duct is useful for cooling the radiator, one could seal both sides of the front grille to remove excessive airflow going under the hood which reduces the cooling and total drag of the vehicle. Several design iterations involving a variety of air-duct geometries and front grille openings were investigated. The results were compared in terms of airflow uniformity, total mass flow rate through the radiator and total vehicle drag to determine the combination that gives the best performance.
Zhang, Chunhui, Uddin, Mesbah, Song, Xu, Fu, Chen, Foster, Lee
Integrated Aero-Thermal Testing of a Race Car in a Full Scale Climatic Wind Tunnel2016-01-15884/5/2016
Wind tunnels with integrated aerodynamic and thermodynamic testing with yaw capabilities are not common. In this study however, an integrated aerodynamic and thermodynamic testing system with yaw capabilities is developed and applied in the climatic wind tunnel at the University of Ontario-Institute of Technology (UOIT). This was done by installing an incremental force measuring system (FMS) on the large turntable that features a chassis dynamometer. The testing system was utilized to implement an integrated aero-thermal test on a full-scale race car. An efficient testing protocol was developed to streamline the integrated testing process. The FMS was used to enhance the test car’s stability, cornering speed, and fuel efficiency by using aerodynamic devices. These objectives were achieved by installing a high rear wing to increase the rear downforce, a modified front splitter extension to produce a front downforce gain, and front canards to contribute to drag reduction. In addition, a thermodynamic test was conducted to study the effect of yaw on upperbody and underbody temperature distribution during the car’s operational condition. Temperature analysis from this test revealed that radiator performance was jeopardized in yaw. It also showed that some aerodynamic devices (such as a rear diffuser) can contribute negatively to the underbody cooling performance of the car. The implications of this study demonstrate that the climatic wind tunnel at UOIT is a viable tool for integrated motorsport testing, which can be used to achieve a significant competitive advantage.
Abdel-Rahman, Abdalla, Agelin-Chaab, Martin, Elfstrom, Gary, Komar, John
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
Full Vehicle Aero-Thermal Cooling Drag Sensitivity Analysis for Various Radiator Pressure Drops2016-01-15784/5/2016
Simulations are presented which fully couple both the aerodynamics and cooling flow for a model of a fully engineered production saloon car (Jaguar XJ) with a two-tier cooling pack. This allows for the investigation of the overall aerodynamic impact of the under-hood cooling flow, which is difficult to predict experimentally. The simulations use a 100 million-element mesh, surface wrapped and solved to convergence using a commercially available RANS solver (STARCCM+). The methodology employs representative boundary conditions, such as rotating wheels and a moving ground plane. A review is provided of the effect of cooling flows on the vehicle aerodynamics, compared to published data, which suggest cooling flow accounts for 26 drag counts (0.026 Cd). Further, a sensitivity analysis of the pressure drop curves used in the porous media model of the heat exchangers is made, allowing for an initial understanding of the effect on the overall aerodynamics. An analysis is made of the various pressure drops on the overall vehicle drag with a breakdown of the most affected components. Simulations suggest that at 50 kph, containing fan driven cooling flow, a linear relationship can be obtained where a variation of 1% in the pressure drop can result in the drag count changing by 0.02 drag counts (0.00002 Cd). An increase in the pressure drop is predicated increase heat exchangers drag, but a combination of the higher momentum loss in the heat exchangers and consequently lower flow velocities downstream at the engine and firewall, along with cooling outflow re-attaching to the under body of the vehicle combine for an overall predicted drag reduction. Further the system is studied without the radiator resulting in an increase of drag over the baseline case of 5 drag counts (0.048 Cd), indicating the need to reduce airflow downstream of the radiator. When blanking the radiator itself a drag difference of 18 drag counts (0.018 Cd) was obtained, further emphasizing the importance of the downstream region.
Simmonds, Nicholas, Tsoutsanis, Panagiotis, Drikakis, Dimitris, Gaylard, Adrian, Jansen, Wilko
Development of an Efficient Power Train Cooling System with Effective Utilization of Front End Opening for a Utility Vehicle2016-01-06524/5/2016
This paper reports a study on Charge air cooler effectiveness, Air intake pressure drop, Acceleration Performance and Rise over ambient temperature of a utility vehicle for different layouts of Inter cooler, radiator, condenser and fan module in order to finalize an efficient Power train cooling system layout. The main objective is effective utilization of front end opening area, eliminating inter cooler heat load on the radiator, so that radiator size, fan size and fan motor wattage can be optimized to achieve desired cooling performance requirements with the cooling system (CRFM) module. Effect of the intercooler effectiveness, Intake pressure drop, Vehicle acceleration performance and Rise over ambient temperature are studied and both the advantages and disadvantages of the proposals are discussed to finalize the better position of inter-cooler along with other engine cooling components.
Ranjan, Ravi, Brahmasani, Lakshmaiah, Khan, Parvej
Development of a Rear Powertrain Cooling System for a Minivan2016-01-06544/5/2016
The paper presents the development of a proposed rear powertrain cooling system of a minivan. The packaging of cooling system is finalized such that the radiator faces towards the rear of the vehicle bumper which is opposite to the conventional rear cooling system (i.e. radiator faces towards the front of the vehicle). In the small minivan, the space ahead of the engine is used as a floor for passenger foot. Due to these space constraints, the cooling system has no choice, but to move rear of the vehicle and above the departure plane to meet packaging requirements. Furthermore, in the conventional rear cooling system, in front of the radiator, there is engine and exhaust system, which heats up the air going to the radiator and reduces radiator cooling performance. Thus the cooling system is placed such that the radiator faces the rear bumper to draw in cooler air. In this condition we don’t depend on the ram air but on the fan to meet required airflow. 1D simulation using LMS-Amesim and CFD tools FLUENT are used for conceptual study. Comparison study on air flow, cooling performance and under-hood temperature is done by testing on a mule vehicle. Grill opening, departure angle, critical components heights and surrounding body panels for underbody are considered in packaging of the vehicle. The air flow, ROA of Coolant and ROA of Oil are measured for two conditions, i.e. radiator facing towards rear bumper and radiator facing towards powertrain. It is observed that the effect of rear vortex has negligible impact on the airflow provided by the fan, for vehicle speed less than 65kmph.
Brahmasani, Lakshmaiah, K, Sarangapani, Solomon, Samson, Khan, Parvej
Optimization of Vehicle Electrical Energy Consumption2015-01-28829/29/2015
This paper focuses on optimizing the electrical energy consumption of vehicle. By introduction three concepts. 1) Innovative speed control logic for radiator fan motor according to vehicle speed and air flow through radiator. 2) Introducing regeneration of energy from radiator fan motor while free running and deceleration of vehicle. 3) Using BLDC motors (generation mode and motoring mode) in radiator and blower motors. About 50 % of total electrical energy consumption of vehicle is contributed by radiator fan motor and blower motor (proven data by performing alternator charge balance test during NEDC cycle). By introducing above three concepts, 50 % electrical energy consumption can be reduced to 25 - 30 %, which gives more than 3.5 % fuel economy improvement and more than 10 gmCO2 reduction per kilometer. Further reduction in conducted emission at motor level, soft starting for radiator fan and blower motor and elimination of high inrush current.
Shah, Abhishek, Karthick, R. R., Aravindan, V, Phegade, Sanjay, Murugesh, Sappani
Loop Heat Pipe with Thermal Control Valve for Variable Thermal LinkTBMG-225378/1/2015
Existing technologies [Loop Heat Pipe (LHP) and passive Thermal Control Valve (TCV)] are integrated and made to work together to provide a passive variable thermal link. The result is a novel LHP with passive TCV that was developed to provide variable heat rejection (turn-down) allowing efficient operation during periods of low dissipation and cold environments, as well as periods of peak loads and warm environments. The thermal control valve installed in the vapor line routes the vapor flow to the radiator during normal operation, or directly to the compensation chamber during periods of cold radiator sink temperatures or low power. The vapor bypassing the condenser cancels the circulation to the radiator, thereby minimizing heat transport and rejection.
Model Predictive Control for Engine Powertrain Thermal Management Applications2015-01-03364/14/2015
Numerous studies describe the fuel consumption benefits of changing the powertrain temperature based on vehicle operating conditions. Actuators such as electric water pumps and active thermostats now provide more flexibility to change powertrain operating temperature than traditional mechanical-only systems did. Various control strategies have been proposed for powertrain temperature set-point regulation. A characteristic of powertrain thermal management systems is that the operating conditions (speed, load etc) change continuously to meet the driver demand and in most cases, the optimal conditions lie on the edge of the constraint envelope. Control strategies for set-point regulation which rely purely on feedback for disturbance rejection, without knowledge of future disturbances, might not provide the full fuel consumption benefits due to the slow thermal inertia of the system. A solution to this problem is to design a control strategy that utilizes an estimate of variability of future disturbances. In this work, we consider the design of a controller for direct optimization of fuel consumption which allows for improved handling of constraints on temperatures and actuators. We propose a robust Model Predictive Control (MPC) formulation to optimize fuel consumption. The controller formulation guarantees that temperature constraints are met for future load and speed profile within specified bounds. The performance of the proposed controller is demonstrated through simulations on a system that uses an electric water pump, active thermostat and radiator fan, to control engine oil and metal (lumped block/head mass) temperature during regular driving so that fuel consumption is minimized.
Karnik, Amey, Pachner, Daniel, Fuxman, Adrian M., Germann, David, Jankovic, Mrdjan, House, Christopher
Design and Control of a Light-Weight Drive-Integrated 48 V BLDC Motor for Radiator Fan in Hybrid Vehicle2015-01-12074/14/2015
In small car segment, as far as hybridization is concerned, the space and safety constraint demands use of lower voltage viz., 48 V as compared to >100-volt-systems used for vehicles in other segments. These systems also have advantage of reduced copper weight due to reduced current. As 12 V systems are replaced by the 48 V systems, the auxiliary 12 V loads would necessitate implementation of a DC-DC converter. Considering the requirements of auxiliary loads that are fed from 12 V battery, the power rating of the DC-DC converter can get considerably high resulting in increased size. Hence, it is advisable to re-design at least some of the 12 V auxiliary systems to 48 V such as the radiator fan motor. This, along with the issues faced in the existing PMDC Motor with regard to efficiency and sizing have generated interest to investigate better alternatives for the motor. To this end, this paper describes the design, development and control of a Brushless DC Motor to be used as a radiator fan. The improved design results in weight reduction and increase in percentage efficiency by about 30 compared to the conventional DC Motor. In addition, issues like sparking and maintenance of brushes for a 48 V DC motor are also eliminated. A low-cost integrated PCB controller is developed to implement the control strategy using Microchip PIC 2231 micro-controller. Finally, the drive is implemented and tested with the radiator fan and the results are presented.
Kane, Makarand, Kulkarni, Swanand, Antony, Shinto, Kharat, Rohit, Chaithanya, Naga
Optimizing the Geometry of Fan-Shroud Assembly Using CFD2015-01-13364/14/2015
Underhood thermal management is a challenging problem in automotive industry. In order to make sure that vehicle works efficiently, there should be enough airflow through the cooling system so that the consequent heat rejection would be adequate. In idle condition the required air flow is provided by the cooling fan so a better understanding and an accurate predictive CAE tool for fan is very beneficial. Computational Fluid Dynamics (CFD) has been extensively used in predicting aerodynamic performance of automotive components. In the current work, the airflow performance of a fan, shroud and radiator assembly was simulated using Moving Reference Method (MRF) method. Although it is less expensive than Sliding Mesh (SM) method, the CAE results compare well with the test data. The simulation was carried out over 10+ different shrouds and the effect of geometrical parameters on airflow was investigated. The CFD data show that the smoothly converging shroud will lead to higher flow rates while cavities and steps will act as a restriction and degrade the efficiency. Besides, it is seen that decreasing the fan tip clearance up to 17 mm will improve the air flow as it prevents the leakage of the pumped flow, but if we go further in reducing the clearance, the airflow does not increase and may even decrease, which may be explained based on the interference of blade and shroud boundary layer. Extending the shroud will not help the air flow and it is recommended to immerse almost 70% of the fan into the shroud. This is a rule of thumb but may vary based on the details of fan assembly.
Mehravaran, Meisam, Zhang, Yi
Open Grille DrivAer Model - First Results2015-01-15534/14/2015
Cooling air flow is an important factor when it comes to vehicle performance and operating safety. In addition, it is closely linked to vehicle aerodynamics. In recent years more and more effort is being spent to optimize the losses generated by the flow through the vehicle. Grille shutters, better sealing and ducting are only some examples for innovations in this field of work, resulting in a lower contribution of the cooling air flow to overall drag. When investigating those effects, both experiments and numerical simulations are commonly used in the automotive environment. Still, when comparing the results from both methods, differences in the effect of cooling air flow can often be observed. To better understand the effects of cooling air flow, the ECARA Subgroup CFD decided to establish a common design for a generic open source vehicle model with a detailed underhood compartment to lay the foundation for a common investigation model. The DrivAer-model, developed at the TU Munich, was chosen as the baseline vehicle, due to its high level of detail and the good acceptance in the community in recent years. Based on the input of the members of the group, FKFS designed a baseline version of the underhood compartment including a radiator package with fan and a representation of the engine in close cooperation with TU Munich. Since the majority of DrivAer models built are for scale model testing, the engine features a simplified design to be used as a starting point for CFD validation. This simplified design fits well to the level of detail of the original model. The underhood flow can both exit through defined openings in the front wheel houses and into the underfloor region, which allows different cooling air concepts to be investigated. The cooling air package is based on component data of a mid-size passenger car. This paper gives some insight into the model and presents first results from both CFD and wind tunnel measurements in quarter scale including rotating wheels and state-of-the-art ground simulation.
Wittmeier, Felix, Kuthada, Timo
Testing and Development of an Enhanced and Cost Effective Engine Split Cooling Circuit2015-01-16504/14/2015
The drive to reduce CO2 and fuel consumption from passenger cars requires improvements from various subsystems. In particular, the ever growing importance of effective and efficient thermal management will no doubt benefit the quest for more efficient vehicle. While many established automakers have decided to increase the sophistications of the engine cooling circuits through electronics, the increase in complexity and costs are still not desirable especially for A and B passenger car segments. With this in mind, simple mechanical based cooling systems with enhanced functionalities are in high demand. To meet such demand, a simplified engine split cooling circuit previously proposed, simulated and reported seems to be promising. To further verify the indicated advantages, a prototype unit was built and physically tested using a dynamometer with motoring capability. The test results obtained are encouraging with several distinctive advantages over the conventional serial and parallel cooling circuits. With low circuit pressure losses, the cabin heater can be placed in between the engine and radiator thus eliminating the need for as much as 40 LPM of coolant to be returned to the water pump to avoid flow stagnation. With a lot more coolant flow going to the radiator, the standard water pump pulley was replaced with a bigger one to reduce the flow rate and the pump's power consumption. Engine FMEP measured using motoring dynamometer showed reduction in power consumption across the engine speed. With higher flow rate and flow velocities across the cylinder head combined with lower coolant temperature inside the cylinder head, the knock resistance of the engine is improved significantly. Spark ignition timing sweep using RON 95 fuel has also shown significant spark advance potentials across the engine speed. The positive test results obtained so far have proven that the proposed simplified engine split cooling has a big potential to meet the demands of future engines.
Osman, Azmi, Hussin, Mohd Asmu'i, Zainal Abidin, Shaiful Fadzil
A Smart Engine Cooling System - Experimental Study of Integrated Actuator Transient Behavior2015-01-16044/14/2015
Smart thermal management systems can positively impact the performance, fuel economy, and reliability of internal combustion engines. Advanced cooling systems typically feature multiple computer controlled actuators - a three way smart valve, a variable speed pump, and a variable speed electric radiator fan(s). To investigate the contributions of these electro-mechanical devices, a scale multifunction test bench was constructed which integrated these actuators, accompanying system sensors, and a controllable engine thermal load with real time data acquisition and control hardware/software. This paper presents a series of experimental studies that focus on the engine's thermal transient response to various actuators input control combinations. The test results established a basis for several key operating conclusions. First, the smart valve and variable speed pump impact the engine temperature by changing the heat transfer rate between the engine and the radiator through coolant redirection and/or coolant flow rate. On the other hand, the radiator fan(s) operation affects the engine's temperature by changing the heat rejection rate of the radiator which can influence the entire cooling system. Third, the smart valve's operation changes the engine's temperature magnitude the greatest amount (4.0%) followed by the radiator fan(s) (1.6%) and coolant the pump (0.5%). Finally, from a power consumption aspect, the radiator fan(s) consumes the most engine power in comparison to the two other actuators. Overall the experimental results offer insight to the control engineers for creating the frame work for advanced engine cooling system control algorithms.
Wang, Tianwei (Thomas), Wagner, John R.
Controlling Variable Coolant Temperature in Internal Combustion Engines and its Effects on Fuel Consumption2014-32-006411/11/2014
Increasing the efficiency and durability of internal combustion engines is one of the major concerns of engineers in the development of modern road vehicles. Emission legislations are becoming intensively strict each year, forcing manufacturers to deploy sophisticated engine control strategies. The engine coolant temperature is conventionally controlled with mechanical elements such as wax-thermostat and belt-driven mechanical water-pump, which result in engine temperature fluctuations and delayed response to variable inputs. Variable coolant temperature is beneficial; it can decrease the hydrodynamic frictional losses of lubricated engine parts in light duty conditions. Moreover it improves performance and protects engine parts from thermal stresses and sealing failure in heavy duty conditions. In this paper the feasibility of controlling coolant temperature is examined in different driver demand conditions using electric flow-control valve replacing conventional thermostat. Urban, extra urban and highway cycles are tested on Honda insight 2003 (without the electric motor) from Advisor software vehicle simulator. The engine conditions, speed and load, in corresponding cycles have been derived and used as an input to Matlab Simulink model consisting of engine cooling components, table of optimized coolant temperature and Brake Specific Fuel Consumption calculation algorithms. We demonstrated that fuel consumption savings of more than 1% in urban and extra-urban cycles can be achieved, however fuel consumption in highway cycle show negligible advantage. The system responds quickly to cooling since there is an amount of cold water reserved in the radiator; however the response is delayed in warming trends.
Khanjani, Koorosh, Deng, Jiamei, Ordys, Andrzej
Performance Calculation of a Vehicle Radiator Group Based on CFD Simulation with Modified Standard Functions2014-01-258610/13/2014
To shorten the development cycle and ensure the stability of the products, based on RNG k-e turbulence model and porous model, 3 dimension (3D) flow field Computational Fluid Dynamics (CFD) simulation is adopted to calculate the radiator group performance for a engineering vehicle being developed. Air-side flow field simulations of the radiator unit model are carried out firstly to obtain the radiators' air-side characteristics; then, the air flow and heat transfer in the whole air channel containing the radiator group are simulated simultaneously to get the inlet and outlet water temperatures of radiator group, at last, the real vehicle test is carried out to verify the simulation results. To be emphasized, in calculating the near-wall boundary layer of the radiators' unit model flow field, modified standard wall functions (MSWF) whose calculation grids is same to standard wall function (SWF) and computation accuracy of the near-wall first node velocity is higher than SWF is proposed; and compared to the test values, the radiators' inlet and outlet water temperatures obtained from the flow field simulation process using MSWF has relative error 6.4%, which can meet the accuracy requirement in engineering computation.
Liu, Shui-chang, Gu, Zheng-qi, Li, Li-fu, Zhang, Yong, ZHAO, Wan-dong
A Secondary De-Aeration Circuit for an Engine Cooling System with Atmospheric Recovery Bottle to Improve De-Aeration2014-01-23429/30/2014
In any engine cooling system, de-aeration capability of the system plays a very critical role to avoid over heating of an engine. In general, with recovery bottle engine cooling system there is one vent hose from radiator pressure cap to the recovery bottle and coolant in the bottle is exposed to atmospheric pressure. From this vent hose air bubbles will move to recovery bottle from the engine and radiator when pressure in the system exceeds pressure cap setting. With this arrangement, de-aeration from the engine will happen when thermostat opens only and till that time air bubbles will be in the engine only and in this time there will be chance of overheating at some critical conditions because of air pockets in to the engine water jacket and the entrained air in the cooling circuit. Also, secondly 100 % initial filling cannot be achieved. Thus there is a need for continuous de-aeration irrespective of the thermostat opening/closing position and also to reduce number of filling intervals. This paper reports on improvement of de-aeration by adding a secondary de-aeration circuit for an engine cooling system with recovery bottle for a single cylinder light commercial vehicle. The secondary de-aeration circuit enabled continuous de-aeration for the cooling system with recovery bottle which performs with similar principle of cooling system with degas bottle and also reduced the number of filling intervals during the de-aeration test. This arrangement can be done to get weight and cost benefits over degassing tank, wherever it is technically possible (i.e. Radiator coolant inlet port should be higher than the engine coolant outlet port). The secondary vent added between top most point of the engine before thermostat valve to the radiator filler neck. A study was carried out on a vehicle with and without a secondary vent in the cooling system with respect to De-aeration, Initial filling capacity and Filling time. The test results confirmed significant improvement of de-aeration and initial filling capacity by adding secondary de-aeration circuit for an engine cooling system with recovery bottle.
Brahmasani, Lakshmaiah, Solomon, Samson, Khan, Parvej
Performance Evaluation of Automotive HVAC System with the Use of Liquid Cooled Condenser2014-01-06814/1/2014
Air-cooled fin and tube heat exchangers are used as a condenser in the conventional automotive Heating Ventilation & Air-Conditioning (HVAC) systems. In this study, the use of liquid cooled plate heat exchanger as a condenser in the automotive HVAC systems has been investigated. In the proposed configuration, the cabin heat absorbed by the refrigerant in HVAC system is rejected to the coolant through a liquid cooled condenser and then to the ambient air through a low temperature radiator. Hence, the proposed configuration combines heat rejection from HVAC system with a low temperature radiator circuit of power train cooling. Mixture of Ethylene glycol & Water (coolant), which is used in power train cooling system, is used as secondary fluid in the condenser. Primarily, work done involves design of a liquid cooled condenser, determining boundary conditions for the coolant circuit and evaluation of overall performance of the refrigeration cycle in the HVAC system at various operating conditions. The modified configuration has been evaluated through dynamic simulation of the system in Dymola. Use of a liquid cooled plate heat exchanger as a condenser provides packaging benefits for the system. From the results, conclusions are drawn about the viability of the concept for its integration into a passenger vehicle.
Banakar, Shivakumar, Limperich, Dirk, Asapu, Ramesh, Panneerselvam, Vaishnavi, Singh, Madhu
Study of Cooling Drag Reduction Method by Controlling Cooling Flow2014-01-06794/1/2014
As the demand for improved fuel economy increases and new CO2 regulations have been issued, aerodynamic drag reduction has become more critical. One of the important factors to consider is cooling drag. One way to reduce cooling drag is to decrease the air flow volume through the front grille, but this has an undesirable impact on cooling performance as well as component heat load in the under-hood area. For this reason, cooling drag reduction methods while keeping reliability, cooling performance and component heat management were investigated in this study. At first, air flow volume reduction at high speed was studied, where aerodynamic drag has the greatest influence. For vehicles sold in the USA, cooling specification tends to be determined based on low speed, while towing or driving up mountain roads, and therefore, there may be extra cooling capacity under high speed conditions. In order to decrease airflow volume by front grille opening area reduction, radiator efficiency improvement was investigated. Efficiency improvement enables a decrease in air flow volume without a corresponding reduction in cooling performance. It is known that high airflow velocity distribution on the radiator face causes a reduction in overall heat rejection performance. Methods to reduce this variability of face velocity distribution were studied in order to improve radiator heat rejection efficiency, and through these methods, total airflow volume through the radiator could then be decreased without adverse effects to cooling performance. This airflow volume reduction, although acceptable for cooling performance, creates a problem for component heat load management. Component heat load is represented as a total number of hours spent at a representative temperature. Airflow control was designed in order to balance the combined low and high speed component heat load. Several methods were investigated, including external body flow modification, cooling fan control logic, and fan shroud shape change. Cooling drag reduction was then estimated based on this cooling airflow volume change.
Kubokura, Takashi, Uno, Takahiro, Evans, Nic, Kuroda, Hiroshi, Shindo, Fuminori, Nagahama, Satoshi
Drive Cycle Simulation of A Tiered Cooling Pack Using Non-Uniform Boundary Conditions2014-01-06544/1/2014
In a tiered cooling pack, the airflow through the individual heat exchangers is determined by the package and aperture lay out. Each heat exchanger rejects heat as a function of the internal coolant flows, the cooling airflow and the air temperature. In a typical automotive cooling pack, the cooling airflow will be non-uniform in velocity and temperature due to fans, aperture geometry, exterior flows, heat exchangers and recirculation. In a drive cycle, these boundary conditions will change with vehicle operating conditions like vehicle speed, engine speed, ambient temperature, and altitude. These non-uniform conditions on the cooling pack can lead to significant errors when uniform boundary conditions are assumed in a transient simulation. This error is commonly corrected using vehicle test data. A predictive approach, which eliminates the need for correlation vehicle testing, is presented. This methodology uses a full vehicle airflow simulation in PowerFLOW to determine boundary conditions at the entrance and exit of the cooling package at stabilized operating conditions. GT Suite is used to model the heat exchange and fluid flow within the cooling package. The radiator heat rejection is modeled solely from component characterization. The boundary conditions over the drive cycle are determined by interpolation of the PowerFLOW results and adjustment for ambient conditions. This methodology was applied to the Jaguar XJ, with a two-tier cooling pack, executing a high speed transient drive cycle at the Nurburgring circuit. This methodology predicted transient coolant temperatures to a high level of accuracy from component data and vehicle geometry.
Jansen, Wilko, Amodeo, Joe, Tate, Edward, Yang, Zhongzhou
Passenger Car Front End Optimization Using CFD Simulation2014-01-06274/1/2014
Increased engine thermal load, front end styling and compact vehicle requirements have led to significant challenges for vehicle front end designer to provide innovative thermal management solutions. The front end cooling module design which consists of condenser, radiator, fan and intercooler is an important part of design as it ensures adequate heat removal capacity of radiator over a wide range of operating conditions to prevent overheating of engine. The present study describes the optimization of cooling air flow opening in the front end using CFD methodology of a typical passenger car. The predicted vehicle system resistance curve and coolant inlet temperature to the radiator are used for the selection of cooling modules and to further optimize the front end cooling opening area. This leds to the successful optimization of the front end, selection of cooling modules with significant cost savings by reducing prototype testing and design cycle time.
Regin A, Felix, Agarwal, Abhinav, Mishra, Niraj Kumar
Design of Experiments Enabled CFD Approach for Optimizing Cooling Fan Performance2014-01-06584/1/2014
Increasing demands on engine power to meet increased load carrying capacity and adherence to emission norms have necessitated the need to improve thermal management system of the vehicle. The efficiency of the vehicle cooling system strongly depends on the fan and fan-shroud design and, designing an optimum fan and fan-shroud has been a challenge for the designer. Computational Fluid Dynamics (CFD) techniques are being increasingly used to perform virtual tests to predict and optimize the performance of fan and fan-shroud assembly. However, these CFD based optimization are mostly based on a single performance parameter. In addition, the sequential choice of input parameters in such optimization exercise leads to a large number of CFD simulations that are required to optimize the performance over the complete range of design and operating envelope. As a result, the optimization is carried out over a limited range of design and operating envelope only. In this paper, a Design of Experiments (DoE) based CFD approach has been used to optimize the fan and fan-shroud design of a cooling pack system. The input design variables of Fan Immersion ratio, Fan to Core distance and Shroud Chamfer Length ratio were considered in this study. The performance output variables of mass flow rate, fan power, and velocity uniformity in the radiator core were predicted. The Central Composite Design (CCD) based DoE approach was used to design the layout of the CFD simulations with the goal of maximizing airflow through the fan, minimize the fan power requirement, and maximize the velocity uniformity in the radiator core. The results from these designed set of CFD simulations were used to generate a response surface that linked the input and output variables with a 2nd order accuracy transfer function which was then used to optimize the fan and fan-shroud design.
Srinivasa, Vinod Kumar, S, Renjith, Shome, Biswadip
Under-Hood Air Flow Evaluation of Pedestrian-Friendly Front-End Style Using CFD Simulation2014-01-07624/1/2014
The efficiency of the vehicle cooling system strongly depends on the air flow through the radiator core. The flow through the radiator core in turn depends on other panels that are in the vicinity of the radiator. In this study, the effect of geometrical change at vehicle front-end including the whole bonnet, grille and bumper area is investigated by means of Computational Fluid Dynamics (CFD). Numerical modeling is carried out by means of CAE tools. Simulations are performed for maximum power and maximum torque conditions, monitoring the mass flow rate through the radiator core and velocity contribution over the radiator face. To the velocity field of the airflow, the heat exchangers are represented as porous media and fan module is modeled utilizing Multiple Reference Frame (MRF) approach. The validity of the developed simulation capability is tested by successful comparison with the available experimental data for the base model at the given operating conditions. On studying the model with complete new front-end style, local modifications are applied incorporating adding airguide, flap and anti-recycler in order to enhance the flow distribution in the vicinity of radiator and increase the mass flow rate passing through it. Modifications lead to more than 10% improvement in mass flow rate through radiator core in Pedestrian-Friendly Front-End Style.
Jahani, Kambiz, Beigmoradi, Sajjad
Development of High Performance Radiators by Fin Optimization2014-01-06354/1/2014
Requirements for fuel economy improvement and reduction in the vehicles engine compartment have increased significantly in the pass years. Performances in radiators have driven changes in terms of compactness and weight reductions. By focusing on the air flow we have optimized the radiator fin and developed a high performance radiator. A similar performance was achieved using an 11mm core depth which has 30% weight reduction compared to a 16mm core depth. The purpose of this paper is to present a technical outline about fin optimization.
Ninagawa, Toshihide, Hakamata, Osamu, Pujols, Sergio
Integrated Low Temperature Cooling System Development in Turbo Charged Vehicle Application2014-01-06384/1/2014
The Low Temperature Cooling (LTC) system is commonly developed for secondary cooling function requirements, such as forced induction air cooling, and HEV power electronics module cooling. The large heat transfer capacity of coolant allows for very compact water-cooled heat exchangers to be installed remotely for better underhood aerodynamic characteristics and more compact packaging design. An integrated LTC loop developed on a Hyundai 2.0L Turbo Charged vehicle extends a traditional WCAC (Water-cooled charged air cooler) application to include a water-cooled condenser (WCOND) module. Unlike other published LTC system design approaches, this research project emphasizes underhood airflow improvement strategy and focuses on heat transfer efficiency. This paper discusses the integrated LTC loop configuration, Low Temperature Radiator (LTR) design, coolant flow control, and others. The LTC system prototype design allowed vehicle performance data to prove that a simplified front end cooling module package allows better airflow cooling efficiency.
Song, Xu, Myers, John, Sarnia, Scott
Development of Steel Clad Aluminum Brake2013-01-20549/30/2013
Aluminum based brake rotors have been a priority research topic in the DOE 1999 Aluminum Industry Roadmap for the Automobile Market. After fourteen years, no satisfactory technology has been developed to solve the problem of aluminum's low working temperatures except the steel clad aluminum (SCA) brake technology. This technology research started at Michigan Technological University (MTU) in 2001 and has matured recently for commercial productions. The SCA brake rotor has a solid body and replaces the traditional convective cooling of a vented rotor with conductive cooling to a connected aluminum wheel. Much lower temperatures result with the aluminum wheel acting as a great heat sink/radiator. The steel cladding further increases the capability of the SCA rotor to withstand higher surface temperatures. During the road tests of SCA rotors on three cars, significant gas mileage improvement was found; primarily attributed to the unique capability of the SCA rotor on pad drag reduction.
Huang, Scott, Hwang, Jiann-Yang, Page, Robert, Song, Xiaobin, Wagnitz, Jim, Huang, Nannon, Schaefer, Gerald, Schaefer, Matt
Deepak Condenser Model (DeCoM)TBMG-168527/1/2013
Development of the DeCoM comes from the requirement of analyzing the performance of a condenser. A component of a loop heat pipe (LHP), the condenser, is interfaced with the radiator in order to reject heat. DeCoM simulates the condenser, with certain input parameters. Systems Improved Numerical Differencing Analyzer (SINDA), a thermal analysis software, calculates the adjoining component temperatures, based on the DeCoM parameters and interface temperatures to the radiator. Application of DeCoM is (at the time of this reporting) restricted to small-scale analysis, without the need for in-depth LHP component integrations. To efficiently develop a model to simulate the LHP condenser, DeCoM was developed to meet this purpose with least complexity. DeCoM is a single-condenser, singlepass simulator for analyzing its behavior. The analysis is done based on the interactions between condenser fluid, the wall, and the interface between the wall and the radiator.
Thermal Management Technologies Keep Satellite CoolTBMG-168217/1/2013
NASA’s Landsat 8 Earth-observation satellite, part of the Landsat Data Continuity Mission (LDCM), launched into orbit on February 11, 2013. The satellite is intended to monitor environmental, natural, and manmade changes to the Earth’s surface using two sensitive data-collecting instruments, the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). Throughout the Landsat 8 mission, internal heat generated by the satellite’s electronics must continually be rejected to outer space; maintenance and adjustments are impossible after launch.
Folding Elastic Thermal Surface — FETSTBMG-165986/1/2013
The FETS is a light and compact thermal surface (sun shade, IR thermal shield, cover, and/or deployable radiator) that is mounted on a set of offset tape-spring hinges. The thermal surface is constrained during launch and activated in space by a thermomechanical latch such as a wax actuator.
Phase Change Material for Temperature Control of Imager or Sounder on GOES Type Satellites in GEOTBMG-165956/1/2013
An imager or sounder on satellites, such as the Geostationary Operational Environmental Satellite (GOES), in geostationary orbit (GEO) has a scan mirror and motor in the scan cavity. The GEO orbit is 24 hours long. During part of the orbit, direct sunlight enters the scan aperture and adds heat to components in the scan cavity. Solar heating also increases the scan motor temperature. Overheating of the scan motor could reduce its reliability. For GOES-N to P, a radiator with a thermal louver rejects the solar heat absorbed to keep the scan cavity cool. A sunshield shields the radiator/louver from the Sun. This innovation uses phase change material (PCM) in the scan cavity to maintain the temperature stability of the scan mirror and motor.
Optimized Radiator Geometries for Hot Lunar Thermal EnvironmentsTBMG-163445/1/2013
The optimum radiator configuration in hot lunar thermal environments is one in which the radiator is parallel to the ground and has no view to the hot lunar surface. However, typical spacecraft configurations have limited real estate available for top-mounted radiators, resulting in a desire to use the spacecraft’s vertically oriented sides. Vertically oriented, flat panel radiators will have a large view factor to the lunar surface, and thus will be subjected to significant incident lunar infrared heat. Consequently, radiator fluid temperatures will need to exceed ≈325 K (assuming standard spacecraft radiator optical properties) in order to provide positive heat rejection at lunar noon. Such temperatures are too high for crewed spacecraft applications in which a heat pump is to be avoided.
Air Flow Control Servomechanism for Cooling the Radiator of a Car Engine2013-01-12964/8/2013
The servomechanism for air flow control has as effect on cooling starting by the shorting of warming up engine period with the useful consequences: fuel consumption, wear and pollution decreasing. A method for cooling air flow control is the use of a program-controlled blind who obturates section of the radiator of car engine, especially for reduced ambient temperature (≺+50C). For experiments it is used an electronic engineering installation who contains: two thermo resistances for the coolant temperature at the inlet, respectively at the outlet to the radiator, a flow meter with Hall sensor for measuring the coolant flow in the radiator loop, a Precision Analog Microcontroller and Laptop. We denote the first transient phase when the valves of thermostat become to open and the second transient phase between the extreme positions: valve is fully closed or fully open. The experimental data demonstrate the reduction of second transient phase and a fuel economy in the case of obturated radiator with different positions of the blinds for reduced ambient temperature. The software for data acquisition is executed in C++ or LabVIEW for processing the signals. A mathematical model with strongly nonlinear system of the considered car engine cooling system with conventional thermostat, radiator, engine and heater is simulated in MATLAB/Simulink for an optimal control of the engine. The dynamic model includes hysteresis, since the way the thermostat opens when the temperature rises differs from the way it closes when the temperature decreases and delays introduced in the cooling loop system.
Dascalescu, Spiridon-Cristian-Da, Receanu, Marius
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