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Due to increased demand for improved fuel economy and reduction in CO2 emissions, active grille shutter (AGS) has been considered as one option to increase fuel economy by reducing vehicle drag resistance. An AGS system will allow airflow through the grille when demand on cooling system or air conditioning system is high. Under conditions of light load and moderate ambient temperatures and humidity, the grille does not have to be fully open. A reduction in the effective grille size opening can be achieved by either partially or fully closing the grille through a stepped speed motor actuator. When the grille opening size is reduced, under-hood airflow will decrease. Therefore, the operating points for the grille shutter should take into account the effect of temperature rise for under-hood and underbody components and the performance of the cooling and climate control systems.

Due to the stringent requirements to reduce the tail pipe emissions of NOx, Selective Catalytic Reduction (SCR) systems are used to remove NOx using ammonia. When a urea solution is injected into the exhaust system, urea will undergo hydrolysis and decomposition reaction that produces ammonia. At the catalyst surface, ammonia will react with the exhaust gases to convert NOx into nitrogen, N2 and water, H2O. One of the challenging problems is to make sure the urea solution is available for the SCR system at cold start conditions. At extreme cold temperatures, the urea solution will begin to freeze at −12°C. At the start up of a vehicle under such low ambient temperatures, a heating system is used to provide the heat required for melting the frozen urea. Therefore, there will be a time lag between the vehicle start up and the availability of urea solution to the SCR system.

This paper describes the development of an engineering analysis tool that assesses the life of vehicle components, after exposure to heat. As a standard engineering practice, each component or part of a component has a “long term” and a “short term” temperature goal based on the part’s material physical properties. At higher temperatures, component’s physical properties degrade at a faster rate, and the component’s useful life can be significantly reduced. The extent of degradation depends upon the duration of exposure, the magnitude of the over-temperature and rate of thermal degradation. This tool utilizes actual vehicle test data from test cells or road testing, material physical properties, and expected vehicle duty cycle to determine the expected component life. When component temperature goals are exceeded, the software calculates the total duration of time above the goal temperature.

A fundamental problem in the development of automotive thermal protection strategies is the understanding of the effect of time and temperature on vehicle components life and their performance throughout the life of the vehicle. Due to restrictions on emissions and the stringent requirements for improved fuel economy, the use of polymers and synthetic materials has been widely adopted in automotive applications. It is therefore critical to develop a process to estimate life of engineering materials based on thermal testing and material physical properties. While a series of carefully selected vehicle tests can determine components temperatures during different testing conditions, a need still exists to determine the expected component life and performance throughout the life of the vehicle. Kinetic models have been widely used, in literature, to determine the aging of polymeric and composite materials over time.

Automotive thermal protection is one of the key areas in the vehicle development process. Critical decisions are usually based on temperature measurement during vehicle testing. Thermocouples are most widely used to determine the temperature of each component during specific test cycle. Therefore, the reliability and accuracy of the thermocouple measurements are of significant importance to the design and release engineers. Errors associated with temperature measurements of automotive components may be caused by radiation from exhaust surfaces such as exhaust manifold, catalytic converter, muffler or exhaust pipes. Other sources of error may be caused by the effect of ambient temperature or airflow if thermocouples are not properly installed. Several errors could arise from the attachment method of the thermocouple to the component or material of interest.

During initial phases of vehicle development process, it is usually required to understand the temperature profile for all components. It is usually more effective and less costly if the thermal issues are determined and addressed before actual vehicles are built. Computational Fluid Dynamics (CFD) analysis tools are typically used for thermal management of the vehicle environment. However, for transient thermal analysis problems, running a full CFD requires solving the mass, momentum, and energy equations. This typically requires a lengthy computation time and extensive computer resources. The problem becomes more challenging when trying to conduct CFD analysis for several design iterations and for different duty cycles that may be of a transient nature. Therefore, the application of one-dimensional analysis early in the development phase can help point out the areas of prime concern.

In automotive testing, a chassis dynamometer is typically used, during cell testing, to evaluate vehicle performance by simulating actual driving conditions. The use of indoor cell testing has the advantage of running controlled tests where the cell temperature and humidity and solar loads can be well controlled. Driving conditions such as vehicle speed, wind speed and grade can be also controlled. Thus, repeated tests can be conducted with minimum test variations. The tractive effort required at the wheels of a vehicle for a given set of operating parameters is determined by taking into account a set of variables which affect vehicle performance. The forces considered in determination of the tractive effort include the constant friction force, variable friction force due to mechanical and tire friction, forces due to inertia and forces due to aerodynamic and wind effects. In addition, forces due to gravity are considered when road grades are simulated.

In this paper, the effects of heat exchanger design parameters are investigated. The ease study being investigated here is the parametric analysis of automotive radiator where the hot fluid is the engine coolant and the cold fluid is the ambient air. Key parameters that are considered are the air density, fin thickness, fins height and air temperature. Effect of air density may be a concern since heat exchangers are usually designed, for automotive applications, under atmospheric pressure conditions. Changes in altitude will cause a change in air density. Therefore, the performance of cooling system may be affected by elevation. In this analysis, however, it is shown that the change in air density has very limited or no effect on the cooling system. The fin dimensions play a key role in the overall effectiveness of a heat exchanger. Some cost saving ideas may include reducing fin dimensions such as fin thickness or fin height.

This paper addresses the critical parameters required for development of automotive thermal protection plans. The test conditions should consider the ambient air temperature, exhaust gas temperature, vehicle speed and engine speed. The choice of test conditions is critical in determining potential thermal issues during the development phase. Appropriate design alternatives can then be implemented.

This paper addresses the uncertainties in the thermal protection design process and their effect on the performance of the protected components. Based on the work presented in this paper, it will be possible to determine the confidence level that a given component will be maintained at its design temperature goals. It will also be possible to determine the most influential design parameters. In general, nominal or mean values of design parameters are used in design or rating calculations without consideration to the uncertainties inherent in them. Therefore, an estimate of the overall design uncertainty should be evaluated. Fourier Amplitude Sensitivity Test (FAST) is used to determine the overall design uncertainty, and evaluate design sensitivity to each of the design parameters. The probability or confidence level that a component will meet a certain design target can be determined.

This paper addresses the uncertainties in heat exchanger design and their effect on the expected heat exchanger performance. Based on the work presented in this paper, it will be possible to determine the confidence level that a heat exchanger will meet its design goals, considering the uncertainties in its design parameters. It will also be possible to determine the most influential design parameters. In general, nominal or mean values of design parameters are used in design or rating calculations without consideration to the uncertainties inherent in them. Therefore, an estimate of the overall design uncertainty should be evaluated. Fourier Amplitude Sensitivity Test (FAST) is used to determine the overall design uncertainty, and evaluate design sensitivity to each of the design parameters. The probability or confidence level that a heat exchanger can meet a certain design target can be determined.

Hydrocarbon emissions represent one of the causes for the formation of ozone and other photochemical pollutants in the atmosphere. Hydrocarbons (HC's), their oxidation products and oxides of nitrogen (NO and NO2) react a few hundred meters of air above major cities, in the presence of sunlight, to produce strongly oxidizing components of which ozone is the most prevalent. Motor vehicles contribute to atmospheric hydrocarbons through exhaust and fuel system evaporative emissions. The main factors affecting the amount of fuel vapor generation from the fuel system are tank pressure, fuel properties, and fuel temperature. The degree of control that can be exercised over these factors is limited. Fuel temperature, the only factor that depends primarily on vehicle design and the thermal environment around the fuel system, has a major effect on vapor generation.

The heat pipe is a very highly conductive device for transferring heat over a relatively long distance with a minimum temperature difference between the heat source and heat sink. Very limited research has been done on the applications of heat pipes in automobile design or manufacturing. Several areas for the use of heat pipes include using the heat pipe as a device for controlling the catalytic converter temperature, early warm up of the catalyst bed, heating of the rear defogger and passenger compartment, engine cooling, and oil cooling. Some of the manufacturing applications include the use of heat pipes for the design and control of the die casting cooling system. Similar applications of heat pipes include the use of heat pipe for the control of the solidification process and material flow during injection molding. Other manufacturing applications may include the use of heat pipes for the cooling of machining tools during metal cutting and grinding.