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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.

Power train cooling control is becoming a topic of increasing interest as evidenced by the recent surge of activities that suppliers of automotive power train cooling and HVAC systems are reporting in literature. The goals of these activities are to achieve better fuel economy, lower emissions and increased passenger comfort by controlling coolant flow through the different system components. In order to study any of the ideas in this area, a simulation model must be developed to sift through them for the most practical and effective method to avoid the high cost of hardware builds and long testing hours. This work uses the EASY5 simulation package (a product of the Boeing Company) to model such systems. A model is developed for a pick up truck application and is validated against test results. At this stage, the model has only the basic components namely the radiator, the water pump, a surge (return) tank, hoses and pipes, and the engine thermal load.

The automotive clean-air catalyst system from Engelhard Corporation (PremAir™) consists of a catalyst-coated vehicle radiator and air-conditioning condenser designed to catalytically remove ground-level ozone and carbon monoxide (CO) from ambient air. Although initial on-road testing of the PremAir™ system showed reasonably high ozone conversion activity and satisfactory catalyst durability during the course of relatively low mileage accumulation, the long-term durability of the catalyst coating, its potential negative impact on cooling efficiency and corrosion characteristics, and incompatibility with the existing radiator manufacturing process remain among the issues of some concern. This paper describes an alternative approach to the problem of on-road pollutant destruction, which involves placing a thin catalytic monolith brick immediately behind the uncoated vehicle radiator.

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.

Vehicle acceleration induced pressure spike on the high side of an Air Conditioning (AC) system is causing considerable concerns, especially for systems with high efficiency compressors. Head pressure surge in the order of one to two hundred pounds per square inch can be observed within a time span of 10 seconds or less. As the industry moves to meet increased system durability standards and passenger comfort requirements, clear understanding of the underlying mechanisms is required so that the impact of the head pressure spike can be minimized or eliminated. The present investigation seeks to understand the mechanisms of the head pressure spike phenomenon through both experimental and mathematical analyses. Experimentally, extensive testing has been conducted in environmental wind tunnel. Our mathematical analysis is based on the mass conservation principle for the refrigerant flow through the high side of an AC system.

Concerns about global warming and climate change, combined with the inclusion of HFCs in the Kyoto Protocol as controlled gases, obligate the automotive air conditioning industry to assess the global warming impact of its HFC-134a emissions and develop cost effective mitigation strategies. One option would be replacing HFC-134a with a refrigerant with lower overall global warming impact. This paper demonstrates the feasibility of a secondary loop A/C system in automotive applications. The value of such a system is that it excludes refrigerant from the passenger compartment, thereby allowing the use of non-inert alternate refrigerants, such as hydrocarbons. It includes actual on-vehicle comparisons of A/C cooling performance and system energy requirements for secondary loop versus the current HFC-134a system. Also included is an assessment of the global warming impact advantage offered by a secondary loop A/C 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.

In recent years, Global Warming Potential (GWP) has become as important as Ozone Depletion Potential (ODP) when evaluating a potential refrigerant. Increasing concern over GWP of HFC-134a and its effect on the environment have led international heating, ventilation and air conditioning, and refrigeration (HVAC & R) industries to look at other options. This study documents an assessment of some of the options. It describes simulated performance of R152a and hydrocarbon refrigerants and their potential as alternative refrigerants to HFC-134a in mobile air conditioning systems. In addition, a comparative assessment of the performance of a secondary loop system using these refrigerants is provided.

The focus of the present paper is the energy efficient automotive air conditioning system, which ipso facto is also environmentally friendly from the standpoint of global warming impact. Two efficiency enhancement strategies are presented - one entailing the use of judicious amount of recirculated air and another relying on reduction in the amount of reheating of the chilled air employed in the conventional system. The first strategy, referred to as the air inlet mixture strategy, reduces the air conditioning load by mixing proper amount of recirculated air with the outside air. The second strategy, referred to as the series reheat reduction strategy, reduces reheating of chilled air under low to moderate load conditions. Analytical relations are presented for the determination of reduction in air conditioning load due to mixing of outside air with varying amounts of recirculated air as well as due to reduction in the series reheat.