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A mathematical method for determination of the heat transfer effectiveness of the engine radiator, heater or oil cooler of automobile accounting for the effects of the nonuniformity of the inlet air temperature distribution and the induced nonuniformity of the mass velocity distribution is developed. Using several typical models of the two-dimensional nonuniform inlet temperature distributions of the cooling air flow, the induced nonuniform mass velocity distributions are determined. The heat transfer effectiveness of the unit and its deterioration are calculated for typical operating conditions accounting for this combined effect. A Non-uniformity Factor of the inlet air temperature distribution is suggested as an index for estimating the degree of the deterioration of the thermal performance of the engine radiator, heater or the oil cooler.

A mathematical method for determination of the heat transfer effectiveness of engine radiator accounting for the effect of two-dimensional nonuniformity of the inlet temperature of the cooling air flow is presented. Using several typical models of the nonuniform inlet air temperature distribution, the effectivenesses of the engine radiator are calculated for various design/operating conditions. A Nonuniformity Factor of the inlet air temperature distribution is introduced to characterize the maldistribution of the inlet temperature of the cooling air flow. The effect of the nonuniformity of the inlet air temperature distribution on the sizing of the engine radiator is discussed.

A mathematical method for determination of the heat transfer effectiveness of the air conditioning condenser accounting for the effect of the nonuniform cooling air flow distribution is presented. Using twelve typical two-dimensional air flow maldistribution models, the heat transfer effectiveness of the condenser is calculated. The deterioration of the thermal performance of the condenser due to the effect of the air flow nonuniformity is then determined. The effect of the air flow nonuniformity on the sizing of the condenser is discussed.

Results of a theoretical investigation on the effect of the two-dimensional nonuniformity of air flow through the evaporator of automobile air conditioning system on its thermal performance are presented. Twelve typical two-dimensional air flow maldistribution models of four basic groups are considered. Convection heat transfer coefficients on both flow sides are not considered to be constants. Refrigerant side pressure drop is included in this study. The thermal performance of the evaporator and its deterioration due to this effect are determined for various conditions. The detrimental effect of the air flow nonuniformity on the thermal performance of the evaporator is found to be significant for many typical applications.

A mathematical method to determine the effectiveness of the engine radiator accounting for the effect of the two-dimensional nonuniform fluid flow distributions on both cooling air and engine coolant sides is presented. By using a successive substitution technique, a single equation with the temperature of the heat transfer wall as the unknown variable is obtained from the three heat transfer rate equations. The radiator heat transfer effectiveness and its deterioration due to the effect of the two-dimensional flow nonuniformity on both fluid sides have been calculated for several typical fluid flow distributions. The effect of the flow nonuniformity on the sizing of the engine radiator of automobile is discussed.