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Viewing 1 to 30 of 2389
2010-10-05
Technical Paper
2010-01-2054
Cenk Dinc, Ozgur Arslan, Tolga Akgun, Roger Almenar
The purpose of this study is to present the effects of several design actions on engine cooling performance of a heavy duty construction truck, with the aid of numerical and experimental investigations. The design actions involve the modifications of the front end geometry and implementation of different heat exchangers and fans. The sensitivity of engine cooling performance related to the concerned design changes is monitored with the variation in the engine coolant temperature. Numerical investigations are carried out with the Reynolds averaged Navier Stokes Equations based CFD solver, UH3D, and the results are validated with the experiments conducted at Behr wind tunnel facilities in Stuttgart. It is seen that the experimental results show good correlation with the CFD simulations.
2010-04-12
Technical Paper
2010-01-0412
Jonathan Robert Burns, Henry Hu, Xueyuan Nie, Lihong Han
Powertrain applications of alloy AJ62 arose from its comparative resistance to high temperature deformation among magnesium alloys. In this research, AJ62 permanent-mould cast in different section thicknesses was subjected to immersion corrosion in commercially-available engine coolant. The objective was to determine corrosion behaviour variation among casting thicknesses. Corrosion product accumulation suggests passive film formation, and unlike in other media, the film exhibits certain stability. Extreme thicknesses were used to generate polarization curves for their respective microstructures in engine coolant. Variation with casting section thickness was observed in the curves. These preliminary results indicate coarsened microstructures reduce corrosion resistance of the permanent mold cast AJ62 alloy.
2011-04-12
Technical Paper
2011-01-0421
V. A. Muruganandam, Maruthi Dhulipudi, Uday Korde
Coolant pipes are a prime connection units present in any engines that facilitates the flow of coolant and thereby keeping the engine under its optimum operating condition. Among the several influencing factors that deteriorate engines performance, the coolant leak is also one of the contributors. This could be caused primly due to leakage issues that arises from the pipe press fit zones. Henceforth it is very important to understand the root cause of this press-fit connection failure. The present study deals with press-fit between the pipe and housing in an engine which is subjected to extreme thermal loads (min of -40°C to a max temperature of +150°C) thereby causing the press-fit loosening effect.
2011-04-12
Journal Article
2011-01-0654
Taeyoung Han, Seongyong Park, Uiseong Kim, Chee burm Shin
As battery temperature greatly affects performance, safety, and life of Li-ion batteries in plug-in and electric vehicles under various driving conditions, automakers and battery suppliers are paying increased attention to thermal management for Li-ion batteries in order to reduce the high temperature excursions that could decrease the life and reduce safety of Li-Ion batteries. Currently, the lack of fundamental understanding of the heat generation mechanism due to complex electrochemical phenomena prohibits accurate estimation of the heat generation within Li-ion cells under various operating conditions. Heat from Li-ion batteries can be generated from resistive dissipation, the entropy of the cell reaction, heat of mixing, and other side chemical reactions. Each of these can be a significant source of heat under a range of circumstances.
2011-04-12
Technical Paper
2011-01-0657
Bashar AbdulNour, Mark Doroudian, Mohsen Battoei-Avarzaman
The performance of ground vehicles of all types is influenced by the cooling and ventilation of the engine compartment. An increased heat load into the engine compartment occurs after engine shut down. Heat is transferred from the hot components within the engine compartment by natural convection to the surrounding air and by radiation to the adjacent surfaces. The heat is then dissipated to the ambient mostly by convection from the exterior surfaces. The objective of this study is to develop a Computational Fluid Dynamics (CFD) simulation methodology to predict the airflow velocity and temperature distributions within the engine compartment, as well as the surface temperature of critical engine components during the after-boil condition. This study was conducted using a full-scale, simplified engine compartment of an armored combat vehicle. Steady-state simulation was performed first to predict the condition prior to engine shut down.
2011-04-12
Technical Paper
2011-01-0174
Lisa Larsson, Torbjörn Wiklund, Lennart Löfdahl
The aim of the study was to investigate the cooling performance of two cooling package positions for distribution vehicles by using Computational Fluid Dynamics. The first cooling package was positioned in the front of the vehicle, behind the grill and the second position was at the rear of the vehicle. Each case was evaluated by its cooling performance for a critical driving situation and its aerodynamic drag at 90 km/h, where the largest challenge of an alternative position is the cooling air availability. The geometry used was a semi-generic commercial vehicle, based on a medium size distribution truck with a heat rejection value set to a fixed typical level at maximum power for a 13 litre Euro 6 diesel engine. The heat exchangers included in the study were the air conditioning condenser, the charge air cooler and the radiator. It was found that the main problem with the rear mounted cooling installation was the combination of the fan and the geometry after the fan.
2011-04-12
Journal Article
2011-01-0129
MIng Huo, Chia-Fon Lee
In this paper, experimental investigation on spray atomization and droplet dynamics inside a thermostatic expansion valve (TXV), a component commonly used in vehicle refrigeration system, was conducted. A needle and an orifice were copied from a commercial TXV and machined to be mounted inside a chamber with optical access so that the flow inside the TXV is simulated and visualized at the same time. The break-up and atomization of the refrigerant were documented near the downstream of the orifice under different feed conditions for two TXV with different geometry. A Phase Doppler Anemometry (PDA) system was used later to measure the size and velocity of atomized refrigerant droplets. The results showed that the droplet size variation along the radial direction is slightly decreased at near downstream and increased at farther downstream due to the coalescence.
2011-04-12
Technical Paper
2011-01-0133
Gursaran D. Mathur
An experimental investigation has been carried out to quantify the performance enhancements with a suction line heat exchanger (SLHX) in an AC system with HFO-1234yf as the working fluid. An off-the-shelf double pipe cross fluted SLHX is used for this investigation. System level bench tests are conducted with an AC system from a 2009 MY mid-sized sedan. The test results shows that the AC system performance with HFO-1234yf can be improve up to 8~9% in comparison to a baseline system without a SLHX.
2011-04-12
Technical Paper
2011-01-0135
Daniela Magnetto, Robert de Boer, Abdelmajid Taklanti
This paper describes the development of a Mobile Air Conditioning (MAC) system with a very small impact on the environment. The system based on adsorption cooling is powered by the waste heat recovered from the engine coolant. The advantages of such a system are: a drastic reduction of the fuel overconsumption and the CO2 emission associated to the MAC usage, and the use of water as the refrigerant, which is a no Global Warming Potential (GWP) fluid [1] compliant with the new EU regulation and naturally available. In addition the system being based on thermal compression and not on mechanical compression, is decoupled from the engine operation and has no impact on the vehicle handling. Finally, coupled with a small fuel burner or with a solar panel it can provide air conditioning when the vehicle engine is stop. Thus the system can provide the cabin preconditioning and allows the cabin cooling for those vehicles which are also used for rest or sleeping (truck, camper).
2011-04-12
Journal Article
2011-01-0139
Hanfei Tuo, Algirdas Bielskus, Pega Hrnjak
This paper demonstrates that the implementation of Flash Gas Bypass method can improve the performance of conventional direct expansion R134a mobile air-conditioning system with a microchannel evaporator. This method uses flash gas tank after expansion valve to separate and bypass flash refrigerant vapor around the evaporator, and feed the evaporator with only liquid refrigerant. Pressure drop is reduced and refrigerant distribution is significantly improved, resulting in higher evaporator effectiveness and evaporation pressure. Both lower pressure drop and lifted evaporation pressure allows the compressor to work with lower pressure ratio, saving required compressor work. An experimental comparison of the direct expansion system shows that Flash Gas Bypass method increases the cooling capacity and COP at the same time by up to 16% and 11%, respectively.
2011-04-12
Journal Article
2011-01-0128
Lothar Seybold, William Hill, Jean-Jacques Robin
This paper will examine a mobile air conditioning (MAC) system optimized for efficiency as well as evaporator cooling capacity. Different internal heat exchanger (IHX) capacities and various thermostatic expansion valve (TXV) parameters will be applied using R1234yf refrigerant. Factors that will be considered include IHX heat transfer and pressure drop, TXV superheat setting and slope, the effect of oil in circulation and how these factors impact the efficiency and capacity of the MAC system. The paper describes the test facility used and the test procedures applied.
2011-04-12
Technical Paper
2011-01-0648
Yuji Kobayashi, Itsuhei Kohri, Yukio Matsushima
MRF method is commonly used for predicting cooling performance to design vehicle engine cooling systems. Especially, the practical prediction of the cooling fan performance is one of the important issues. In the design phase of the vehicle development, combinations of multiple parameters are generally examined. Therefore, the steady RANS coupled with MRF method is indispensable. However, unfortunately, the current method does not always give enough accuracy to practical vehicle design. Thus, this paper describes that the method to determine adequate MRF-region to predict the fan performance in practical accuracy.
2010-04-12
Technical Paper
2010-01-1254
Charles Lizhi Zhu, Miaosen Shen, Matthew Obrigkeit
One potential system configuration for future hybrid electrical vehicles (HEV) is to use a single coolant loop for both internal combustion engines and power electronics inverters/converters. Under these conditions, coolant temperatures could be as high as 105°C. This paper proposes a high power DC/DC converter topology suitable for high temperature application. The new interleaved topology implements the power sharing on both high voltage side and low voltage side to alleviate the thermal stress. The DC/DC converter topology features a wide soft switching range to reduce the switching loss of the power semiconductor devices. In addition, a power module design approach is proposed to reduce the thermal resistance of the power semiconductor devices. The power-module-based approach provides for a higher level of integration by means of a wirebond-interconnected power stage.
2010-04-12
Technical Paper
2010-01-0801
Vivek Kumar, Sachin A. Shendge, S. Baskar
Underhood environment of a passenger vehicle consists of critical components such as heat exchangers, engine, batteries and exhaust system with complex geometries. The exterior styling and the packaging constraints along with the aerodynamic requirements of minimal grill opening areas result in a compact and packed underhood. In such a restricted environment the volume of air flow entering the underhood reduces. The airflow management issues become even more severe in case the underhood environment is located at the rear end of the vehicle, away from the ram air zone available in front of the vehicle, as is the case in the present study. In recent times, a combination of 1D and 3D simulations have gained a high importance to conduct air flow and thermal simulations of vehicle underhood to understand the complex interactions of air flow velocities and temperatures.
2013-04-08
Technical Paper
2013-01-0799
Sachin R Kamath, Prajwal Kumar M P, Shashank S N, Vinay Damodaran, Anand S R, Prakash Kulkarni
Engine overheating problems have been the major cause for vehicle breakdown during FSAE endurance runs. Therefore, it is crucial to study the cooling performance, which is affected by the air flow through the side-pod. CFD is used as a tool for this study and simulation based on the complete race car 3D model (NITK Racing 2012 formula student race car - NR XII) is carried out for different cases. Further, Wind Tunnel Experiment is carried out to validate these results. The results obtained for different cases are analyzed to decide the best configuration of the cooling duct. CFD analysis helped in calculating the mass flow rate through the radiator at various velocities. Pressure distribution and velocity distribution were also obtained along the length of the side-pod for different velocities of the car. Area of flow separation and turbulence is visualized and thus smooth airflow into the radiator core area is ensured.
2013-09-08
Technical Paper
2013-24-0142
Samer Saab, Jean-François Hetet, Alain Maiboom, François Charbonnelle
The tightening restrictions, in terms of fuel consumption, have pushed the vehicle manufacturers and equipment suppliers into searching for innovative ways to reduce the carbon dioxide emissions. Along with the ameliorations added to the engine itself, additional systems are grafted to the engine in order to keep up with the ever-changing laws. Isolating the impact on the fuel consumption of an added system, by on board testing, is a complicated task. In this case, using simulation modeling allows the reduction of delays related to prototyping and testing. This paper presents modeling of various thermal systems in a vehicle and their interactions to evaluate the fuel consumption using AMESim software. As means to reduce the CPU cost of the model (calculation time), without decreasing its predictability, engine modeling has been done by two steps: high frequency model and mean value model.
2004-03-08
Technical Paper
2004-01-1507
E.C. Chan, G. Karimi, D. Rose, J.R. Culham
This paper presents a comprehensive steady-state numerical study for an occupant-loaded vehicle seat with internal heating under severe winter conditions. A participant-based postural study showed that the nominal peak occupant seat pressure was 6kPa on the seat cushion, and 2.5kPa on the backrest. Uni-axial compression tests also indicated non-linear stress-strain behaviors in seating. Using an internally developed 3-D numerical model, it was found that the thermal resistance from contact and clothing was uniform (hc=144W·K−1·m−2) throughout the occupied regions. Their contribution to the overall thermal resistance was relatively minor, however, compared to that of skin (hoverall=27.2W·K−1·m−2). The thermal-mechanical simulations were conducted at heat input levels between 20W and 80W, using I-DEAS 10 and the TMG package as the simulation platform. Comparisons was also made between occupied seat with deflected and non-deflected mesh.
2004-03-08
Technical Paper
2004-01-1506
Chris Swales, Christoph Capellmann, Matt Crompton, Marcus Matthes
Customer clinics and surveys have revealed the increased importance to the customer of good defrost and demist performance in their vehicle. Achieving this level of performance, within the time and cost constraints of a modern vehicle development program, places increased reliance on computational (CAE) techniques. However, this paper describes how the optimum development process should be to combine this reliance upon CAE methods with a newly developed experimental technique. This new laser Doppler velocimetry (LDV) based methodology is employed at all stages of the development process and complements the CAE techniques perfectly. The end result is optimized airflow management within the vehicle cabin – essential if good defrost and demist performance is to be achieved in a vehicle.
2004-03-08
Technical Paper
2004-01-1509
Gaurav Anand, Milind Mahajan, Nagendra Jain, Balaji Maniam, Todd M. Tumas
e-Thermal is a vehicle level thermal analysis tool developed by General Motors to simulate the transient performance of the entire vehicle HVAC and Powertrain cooling system. It is currently in widespread (global) use across GM. This paper discusses the details of the air-conditioning module of e-Thermal. Most of the literature available on transient modeling of the air conditioning systems is based on finite difference approach that require large simulation times. This has been overcome by appropriately modeling the components using Sinda/Fluint. The basic components of automotive air conditioning system, evaporator, condenser, compressor and expansion valve, are parametrically modeled in Sinda/Fluint. For each component, physical characteristics and performance data is collected in form of component data standards. This performance data is used to curve fit parameters that then reproduce the component performance.
2004-03-08
Technical Paper
2004-01-1508
Se-Gil Park, Jin-Bok Kim, Sung-ho Song, Jang-hyung Cho
This study validated the process of air ventilation design and the increase of air ventilation performance using CFD(Computational Fluid Dynamics). The application to computing external flow include passenger compartments are designed by one model using new method. The shape and configuration of the air ventilation system determine the ventilation performance. Therefore, the air ventilation system configuration in the early stages need the aerodynamics simulation results of the cowl top, intake duct, blower, HVAC, passenger room and exit. Achievement of these design guides and new development process will be satisfied with predicting the ventilation performance in a short term and cutting down expenditure.
2004-03-08
Technical Paper
2004-01-1505
M.H. Shojaee, Fard P.H. Tehrani, A. R. Noorpoor, M. R. Adili
1 ABSTRACT The need to improve the climatic comfort within passenger vehicles is critical not only to passenger comfort but also to their safety. However, to make progress in this area, a good understanding of the flow behavior within the vehicle is required. In this paper, we use three-dimensional computer simulations to analyses the flow fields and temperature distributions of Heating, Ventilation and Air-Conditioning (HVAC) system of a generic passenger car. We examine the role of HVAC configuration and design parameters, such as air temperatures and velocities at the inlets, the size number and location of the system's inlets and outlets. In this way the model is simulated first for normal mode with 4 front outlet and then the model is optimized by adding a rear outlet, mounted on the back of the console. The models are designed and meshed in GAMBIT environment and solved in FLUENT 5.23software.
2004-03-08
Technical Paper
2004-01-1504
Tomohiro Waku, Norihiko Watanabe, Joji Matsumoto, Junichi Nakanishi
A windshield defroster has an important roll of clearing up fogged window glasses of a vehicle by blowing out warm air. In simulations parameters that affect the defogging time are the velocity, humidity and temperature of the flow from a defroster nozzle. However, individually varying all the parameters and investigating their effects will lead to many computing cases and long runtime. An approach that can considerably reduce calculation time is proposed. The approach is dictated by two key-steps: 1) First, steady-state velocity distributions for several different defroster flow rates are calculated; 2) Secondly, based on the pre-calculated velocity fields, the defogging time is estimated. This approach is compared to the conventional method that always couples all the parameters in transient calculations.
2004-03-08
Technical Paper
2004-01-1511
Adrian Tentner, Paul Froehle, Chung-Yi Wang
This work has explored the preliminary design of a Computational Fluid Dynamics (CFD) tool for the analysis of transient vehicle underhood thermo-hydrodynamic events using high performance computing platforms. The goal of this tool will be to extend the capabilities of an existing established CFD code, STAR-CD [1], allowing the car manufacturers to analyze the impact of transient operational events on the underhood thermal management by exploiting the computational efficiency of modern high performance computing systems. In particular, the project has focused on the CFD modeling of the radiator behavior during a specified transient. The 3-D radiator calculations were performed using STAR-CD, which can perform both steady-state and transient calculations on one of the cluster computers available at Argonne National Laboratory. Specified transient boundary conditions, based on experimental data provided by Adapco and DaimlerChrysler were used.
2004-03-08
Technical Paper
2004-01-1510
Todd M. Tumas, Balaji Maniam, Milind Mahajan, Gaurav Anand, Nagendra Jain
This paper describes a vehicle-level simulation model for climate control and powertrain cooling developed and currently utilized at GM. The tool was developed in response to GM's need to speed vehicle development for HVAC and powertrain cooling to meet world-class program execution timing (18 to 24 month vehicle development cycles). At the same time the simulation tool had to complement GM's strategy to move additional engineering responsibility to its HVAC suppliers. This simulation tool called “e-Thermal” was quickly developed and currently is in widespread (global) use across GM. This paper describes GM's objectives and requirements for developing e-Thermal. The structure of the tool and the capabilities of the simulation tool modules (refrigeration, front end airflow, passenger compartment, engine, transmission, Interior air handling …) is introduced. Model data requirements and GM's strategy for acquiring component data are also described.
2004-03-08
Technical Paper
2004-01-1513
Tarun Malik, Clark Bullard
HEVs idle their engine during the stops to meet the cooling loads. However, idling reduces fuel economy and increases emissions and engine wear. The paper focuses on exploring alternative strategies for air conditioning the HEV during stop times. Simulation analyses are used to identify fundamental differences and new technology tradeoffs encountered in HEVs. An analysis of cooling loads on a car under typical weather and driving conditions is combined with efficiency estimates for an advanced a/c system to compare different cooling strategies in terms of fuel usage and overall system COP. Options considered include belt-and electrically-driven compressors, with thermal and electrical storage technologies. The results of this parametric analysis narrow the range of cooling strategies to be considered for detailed analysis and prototype testing.
2004-03-08
Technical Paper
2004-01-1433
Basel Ismail, Daniel Ewing, James S. Cotton, Jen-Shih Chang
A non-destructive neutron radiography technique was used to measure the thickness of diesel soot deposited in the tubes of exhaust gas recirculation (EGR) cooling devices. Measurements were performed to characterize the fouling in single-tube and three-tube devices for laminar and turbulent flows. Measurements were also performed to characterize the effect that the design of the inlet header had on the deposition characteristics in the device. The analysis of the neutron images showed that the soot deposition in the single-tube device occurred at a faster rate for a turbulent flow than for a laminar flow. The deposition thickness decreased along the tubes for both flow regimes. More soot deposited in the center tube of the three-tube bundle for the expansion angle 45° inlet header suggesting there was an uneven distribution of the exhaust gas flow in the tube bundle.
2004-03-08
Technical Paper
2004-01-1446
Junji Honma, Toshiaki Murao, Youji Yamashita, Makoto Tsujita, Hiroyuki Sugihara
A multi-tube EGR cooler was developed to have high heat exchanger efficiency with high reliability for heavy-duty diesel engine application. Using three-dimensional numerical analyses as well as several laboratory experiments on both a test rig and a diesel engine, the authors determined the most critical factors for developing such an EGR cooler with low production costs. Technology development focused on achieving a high heat transfer coefficient on the gas side in a tube for increased heat exchanger efficiency and uniform coolant flow distribution in the shell for effective cooling of all tubes in the shell. The tube's inside wall was designed with a spiral configuration both for improved gas flow and heat transfer characteristics. Both the layout of the coolant inlet and outlet on the shell and the arrangement of tubes in the shell were optimized for the best results.
2004-03-08
Technical Paper
2004-01-1381
Vito Melisurgo, Emilio Canuto, Domenico Vitali
Environment and A/C loop conditions strongly affect automotive evaporator performance. The aim of the activity is to identify the parameters it depends on and its functional dependence. Several evaporators, differing in size and technology, are tested on a bench, simulating a wide range of working conditions. The evaporator efficiency is introduced in order to correctly evaluate performances. The functional dependences from air velocity and humidity (key parameters) are shown, and a methodology to characterise automotive evaporators is proposed.
2004-03-08
Technical Paper
2004-01-1382
Srinivasan C. Rasipuram, Karim J. Nasr
Impinging jets are an established technique for obtaining high local heat transfer coefficients between a fluid and a surface. Factors such as jet attachment, surface angle, jet angle, separation distance between jet orifice and surface of impingement, and trajectory influence heat transfer dramatically. In the current study, the specific application of interest is air issuing from the defroster's nozzles of a vehicle and impinging on a glass windshield. The current work is aimed at studying the flow patterns off a vehicle windshield as a result of air issuing from various nozzle configurations. The effects of openings' geometry (circular vs rectangular), number of openings, angle that the windshield makes with the horizontal plane and angle of impinging jet, on windshield heat transfer is examined. An optimal configuration will be recommended for better heat transfer.
2004-03-08
Technical Paper
2004-01-1384
Kimiko Imai, Hiroyuki Kato, Tomohide Nishino, Kazuhiro Fukumoto
One of typical outcome of the desire for increasing passenger comfort is that especially for deodorant efficiency. Since customers are becoming so sensitive about cabin odor, development of more effective deodorant filter is strongly required. Out side of vehicle, which most being disliked is diesel odor, therefore, analysis on this diesel gas and investigation to identity the ingredient for the main cause of the strong odor were executed, and found that acetaldehyde gas is the one. Therefore, identification of the chemical that adsorb acetaldehyde gas with being impregnated in activated carbon was required, since activated carbon itself does not have ability of adsorbing acetaldehyde gas, and finally found appropriate chemical, vitamin Bx. At the end of this report, sensory evaluation result by twenty panelists with deodorant type cabin air filter impregnated with vitamin Bx, and its efficiency for deodorant will be shown at the end of this report.
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