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Technical Paper

Validation of 3-D Passenger Compartment Hot Soak and Cool-Down Analysis for Virtual Thermal Comfort Engineering

Simulation of passenger compartment climatic conditions is becoming increasingly important as a complement to wind tunnel and field testing to help achieve improved thermal comfort while reducing vehicle development time and cost. Thermal analysis of a passenger compartment involves not only geometric complexity but also strong interactions between airflow and three modes of heat transfer, namely, heat conduction, convection, and thermal radiation. The present full 3-D CFD analysis takes into account the geometrical configuration of the passenger compartment including glazing surfaces and pertinent physical and thermal properties of the enclosure with particular emphasis on glass properties. This CFD analysis is coupled with a thermal comfort model in the Virtual Thermal Comfort Engineering (VTCE) Process that was described in [1].
Technical Paper

Laboratory Techniques and Tube Alloy Ranking to Improve Internal Corrosion Resistance of Automotive Radiators

Internal corrosion resistance of radiators and heaters is becoming more important as automotive manufacturers seek durability past 10 years, and as the usage of aluminum heat exchangers spreads to markets with poorly maintained engine coolant fluid from a corrosion inhibition standpoint. Simulated Service Corrosion Tests (SSCT) are used to evaluate the resistance of three aluminum alloys to tube failure in various corrosive water and depleted coolant conditions. The paper documents results from such tests that lead to two major conclusions: (1.) A weakly inhibited Oyama water solution with a silicated North American engine coolant is highly effective in ranking internal liner alloys for their pitting corrosion resistance, and (2.) AA7072 lined tubes exhibit superior pitting corrosion resistance compared to 1XXX lined tubes. Electrochemical test data obtained in a simulated pit electrolyte and the bulk test solution are utilized to develop an understanding of the SSCT results.
Technical Paper

CFD Analysis and Validation of Automotive Windshield De-Icing Simulation

Simulation of passenger compartment climatic conditions is becoming increasingly important as a complement to wind tunnel and field testing to help achieve improved windshield de-icing performance while reducing vehicle development time and cost. Windshield de-icing simulation involves not only geometric complexity but also interactions between airflow and two modes of heat transfer, namely, heat conduction and convection. In the present study, CFD is employed to numerically simulate windshield de-icing performance. The general-purpose CFD package Fluent is used to perform the numerical simulation. Two CFD analysis methodologies, windshield de-icing pattern analysis and windshield de-icing process analysis, are discussed. The validation is presented by comparing the CFD predicted windshield de-icing patterns with windshield de-icing tunnel test. The present full 3-D CFD windshield de-icing simulations demonstrated reasonable agreement with available tunnel test data.
Technical Paper

Enhancement of R-134a Automotive Air Conditioning System

The paper deals with potential augmentation of the present R134a automotive air conditioning system with the intent to lower its total equivalent warming impact (TEWI) which is a source of concern from the standpoint of environmental benignity of the system. It is identified that the most effective augmentation strategy includes (1) increase in compressor isentropic efficiency, (2) increase in condenser effectiveness, (3) decrease in lubricant circulation through the system, (4) decrease in air side pressure drop in evaporator through improved condensate management, (5) increase in condenser airflow, (6) decrease in air conditioning load via permissible increase in the amount of recirculated air through the passenger compartment and (7) reduction in direct emission of R-134a from the system through conservation and containment measures. The effect of each of these augmentations on the coefficient of performance (COP) of the system is quantified in a rigorous fashion.
Technical Paper

HVAC System Design and Optimization Utilizing Computational Fluid Dynamics

Computational Fluid Dynamics (CFD) analysis has been used extensively in the design of automotive HVAC systems with the objective of optimize system performance and shorten the product development time. In this paper, the three dimensional Navier-Stokes code STAR-CD was used to determine the overall system pressure drop and velocity field, as well as, individual component pressure and velocity field. In addition, a better insight into the flow characteristics of the HVAC system has been obtained through the CFD analysis. Thermal performance of the HVAC module can also be achieved through the use of user supplied subroutines, which model the thermal effects of heat exchangers. In this paper, two specific systems were analyzed. The first system consisted of a simplified plentum, multiple inlet designs, blower, and evaporator core. The main focus of this analysis was placed on inlet design.
Technical Paper

Applied CFD and Experiment for Automotive Compact Heat Exchanger Development

This paper chronicles a heat exchanger development project that utilized an integrated development process. A combination of full-scale heat exchanger performance testing, flow visualization experiments, and computational fluid dynamics methods were used in concert to investigate flow phenomena in multilouver fins. The primary goal of this project was to confirm the flow and heat transfer enhancement mechanisms at work in multilouver fins. A second goal was correlation of flow visualization, CFD, and traditional full-scale heat exchanger testing. Excellent agreement was found between the three methods.