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The paper describes, in a first part, a conventional architecture of a heat pump system intended to both heat and cool the passenger compartment of an electrical vehicle. It indicates in particular the main disadvantages and performance limitations of such kind of systems. The second part describes an improved architecture of the system including an additional water/R134a refrigerant evaporator and integrated components allowing for an increase in heating capacity and an optimization of the volume required for their integration in the engine compartment. The paper concludes on the measured performances obtained for both heating and cooling mode and indicates the other possible advantages of the proposed system such as its ability to manage the driven batteries temperature.

Nuisance odors from the climatic system of passenger cars, have put in alert the evaporator manufacturers to implement solutions in order to eliminate or reduce the intensity of those odors. There is not much information available in the literature concerning the odors in the climatic system, however, it is recognized that the most important factors contributing to the nuisance odors development in the air conditioning system are: the architecture of the air conditioning system, and the surface treatment of the evaporator. The aim of this paper is to compare the performance, corrosion resistance, and nuisance odors among different surface treatments available in the industrial market and propose solutions to reduce their intensity.

This paper, describes an attempt to calculate the amount of specific net work, efficiency and also heat energy available in the exhaust gases of a turbocharged Spark Ignition engine (ideal cycle) that can be interfaced with an absorption refrigeration unit. The working fluid is taken to be air. Based on the thermodynamics laws the variation of specific net work and efficiency of the engine as a function of the cycle volume ratio, cycle temperature ratio and compressor pressure ratio are calculated. Then by writing a heat balance equation for the cycle the amount of heat available in the exhaust gases is determined.

The Smart VOV™ is a mechanically programmable variable orifice valve ( VOV ) designed to replace the fixed orifice tube used in CCOT ( cycling clutch orifice tube ) automotive air conditioning systems. The VOV decreases suction pressure, reduces a/c discharge air temperature, and provides cooler vehicle interior temperatures relative to a fixed orifice over a wide range of operating conditions. The VOV is also engineered to minimize system equalization noise. This paper describes the VOV development objectives, the key operating principles, and includes wind tunnel, laboratory, and field test results for CCOT systems as well as a TXV ( thermal expansion valve ) performance comparison.

This paper demonstrates the methods used to design an automobile engine cooling system. Basic terminology associated with the cooling system is defined. Topics covered include the radiator, fan, and coolant. The radiator is described in detail. The advantages of aluminum over copper/brass radiators are discussed, as well as the numerous tube, fin, and core designs of automobile radiators. Finally, experimental methods used in radiator and cooling fan selection are discussed. The experimental methods include dynamometer testing and the development of radiator/fan pressure drop vs. volumetric flow rate curves. Experimental data for radiator/fan curves of a typical racing car cooling system are presented. In addition, analytical techniques used to determine the maximum cooling capacity of radiators used for the Comell University Formula SAE Racing Car Team 1996 are described.

An early-design methodology for predicting both expected fuel economy and catalyst-out CO, HC and NOx concentrations during arbitrarily-defined transient cycles is presented. The methodology is based on utilizing a vehicle-powertrain model with embedded maps of fully warmed up engine-out performance and emissions, and appropriate temperature-dependent correction factors to account for not fully warmed up conditions during transients. Similarly, engine-out emissions are converted to catalyst-out emissions using conversion efficiencies based on the catalyst brick temperature. A crucial element of the methodology is hence the ability to predict heat flows and component temperatures in the engine and the exhaust system during transients, consistent with the data available during concept definition and early design phases.

There is today a need to understand the distribution of temperature- and pressure loads and their influence on structural behavior of an automotive cooling heat exchanger. With this knowledge we gain a thorough understanding enabling us to optimize the components efficiently. Experimental analysis is costly and time consuming. This paper presents a method to combine CFD simulations with FE-analysis to evaluate the structural effects of temperature- and pressure loads. This procedure has been carried out for a standard charge air cooler design. The CFD simulation results in accurate pressure and temperature distribution descriptions. These descriptions are used as the boundary conditions for FE-analysis. The output from the final calculation enables to design an optimized charger air cooler from structural aspects.

A global thermal model of a vehicle powertrain is used to quantify how different engine design and powertrain calibration strategies influence the performance of a vehicle heating system. Each strategy is evaluated on its ability to improve the warm-up and heat rejection characteristics of a small-displacement, spark-ignition engine while minimizing any adverse effect on fuel consumption or emissions. An energy audit analysis shows that the two strategies having the greatest impact on heating system performance are advancing the spark and forcing the transmission to operate in a lower gear. Changes in head mass, exhaust port diameter, and coolant flow rate influence the coolant warm-up rate but have relatively little effect on steady state heat transfer at the heater core.

Two primary types of insulating sleeves have traditionally been applied in the thermal protection of automotive hoses and cabling; braided and sewn. Automotive engineers would benefit from understanding the effects of different sleeve types and fit characteristics on thermal performance. A design of experiments was conducted examining the effects of sleeve diameter, sleeve surface emissivity, and sleeve to hose orientation on the heat protection characteristics of an insulating sleeve in an underhood hose application. The temperature data collected showed that, while surface emissivity had a major effect, sleeve diameter and orientation had no significant effect on sleeve performance. Some guidelines are presented to allow engineers to make sleeve selections within the scope of the test. The study will be continued to broaden the scope of the guidelines and establish a theoretical model.

The use of exhaust manifold heat shields in automobiles is increasing rapidly due to emission laws, autoignition temperatures of fluids and packaging constraints. The standard materials are presented and selected composite combinations offered by Midwest Acoust-A-Fiber along with those offered by competition were tested for thermal testing using SAE 135 1 setup and acoustical testing using ASTM C384. The SAE 135 1 showed the thermal performance offered by Acoust-A-Fiber composites to be better than the competition.

The purpose of this study is to develop and demonstrate the techniques needed to perform a computational analysis of a windshield de-icing problem. A numerical model of a simplified test vehicle configuration has been built which includes the passenger compartment air, the windshield and the ice/water layer. A transient analysis was performed for conditions for which cold room test data is available. The results of the numerical simulation show very reasonable agreement with the test data.

First introduced in 1995, the concept of a temperature-responsive Variable Orifice Valve to control refrigerant flow (patent # 5,479,786) has been further developed for use in automotive refrigerant systems. This device is an alternative, to the expansion devices currently used in automotive refrigerant systems and offers the best features of a thermal expansion valve system (similar high ambient performance ) and of a fixed orifice tube system (low cost, high reliability & performance at lower ambients). Typical automotive refrigerant system operation includes wide variations in condenser air flow and refrigerant pressure. The resultant condenser exit refrigerant temperature is a very stable input parameter for the control of this variable orifice valve (VOV).

Heavy truck development is characterized by increasing engine performance, torque and payload, which increases the demand of using hydrodynamic retarder for braking. At the same time there is a demand of reducing exhaust gas emissions and noise and increasing comfort and driving safety. As a consequence manufacturers of heavy duty trucks are demanding higher performance from their cooling systems with less available space in the vehicle. To meet these needs, a novel high performance compact cooling system was developed. This system differs from conventional systems in that it utilizes a radial arrangement of the cooling components that allows up to 1.4 times more heat transfer surface to be installed in the same space with all air side surfaces working at ambient temperature.

A mathematical simulation model was developed to calculate the cooling loads in a cab. The cooling loads calculations are described: Solar irradiation through glasses, conduction through the body walls and glasses, conduction through motor compartment, fresh air intake/infiltrations, people and equipments. Fields experiments were conducted to evaluate the conduction through walls and glasses and the total cooling load models. Precision less than 5% was gotten between experimental measurements and model results. In the summer situation, studies about the effects of the cab orientation, the time, the external paint and the tint of the glasses in changing the conduction and solar radiation cooling loads, were conducted. Cab orientation and the time can change this cooling loads by 225%. Variation by 30% was gotten from different paints and glasses.

An experimental program has been conducted to evaluate the thermal performance, the relationship between surface heat flux and surface temperature, of two engine coolants at off-design operating conditions. These conditions could be caused by high ambient temperature or a faulty system seal. The experimental data shows that system pressure has the most pronounced effect on thermal performance. Lowering the system pressure enhances boiling by reducing the saturation temperature. Using a revised Chen correlation, analytical predictions have been obtained which agree with the experimental results

The thermal design for a new compact circular external type water cooled engine oil cooler has been performed in the present study to meet the use of one of the typical DOHC 4 cylinder gasoline engine. The oil cooler examined in this study is characterized as one of the highly compact water cooling engine oil cooler having no offset strip fin in oil cooler core and no the encasing body housing. The oil cooler in this study is comprised of the heat exchanger core plates made of multiple identical wavy dimples to enhance the heat transfer in oil flow side and body is made of brazed stacking of identical core plates. In the study a thermal design model has been developed for this new compact water cooled oil cooler. The design model is validated through the experimental data of various coolant and oil flow rate plus temperature conditions. Also a predictive theoretical model has been made, based on the application of the actual thermal fluid flow pattern and construction geometry.

First tier heat shield suppliers are becoming increasingly involved in the heat management process and vehicle design drivers affecting business growth are addressed. The shields themselves are taking on a greater degree of functionality, particularly in the area of NVH, and these additional requirements are discussed. The approach to material development is exemplified through a brief case study.

In order to enhance the ability of engineers to quickly and easily evaluate new heat shield materials and construction methods for the underhood and underbody regions of the vehicle, a standardized rig test is being developed. The issues involved in the development of this test method are discussed as well as the important parameters. Test results for different heat shield materials are also presented.

Due to the introduction of new, more stringent exhaust gas emission regulations for diesel engines, expected to be enforced in Europe and the USA in 1999 and 2004, respectively, new emission-reducing technologies are becoming the focus of attention. One such technology is the cooled exhaust gas recirculation method (cooled EGR) which permits a reduction in emissions with only a small increase in fuel consumption. The heat exchanger used in such a system must be capable of meeting high demands in terms of compact design, performance, resistance to high temperatures, corrosion and fouling. The paper describes the development of an EGR cooler designed by Behr which meets these demands and, in particular, has a high performance density. This was achieved by using a new kind of heat exchanger core.

The cooling system is designed on the basis of thermally critical operating conditions. For thermally uncritical partial-load conditions under which a vehicle normally operates during most of its service life thermal-management measures offer considerable potential for reducing the impact of the motor vehicle on the environment. At the same time they are enhancing passenger and driver safety and comfort. These objectives can be achieved by using newly developed actuators in conjunction with intelligent control systems. As part of its thermal management strategy Behr is developing new kinds of actuators, system configurations and control algorithms which permit demand-responsive control and supply of mass and heat flows.