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Side-by-side arrangement of condenser and radiator in the cooling air circuit of automobile requires smaller exchanger core volume and less fan air horsepower than those required in the back-to-back arrangement for the same thermal performance requirements under same operating conditions. Side-by-side arrangement also contributes significantly to the improvement of overall system efficiency and fuel economy. A set of criteria in terms of Relative Radiator Core Volume and Relative Radiator Fan Air Power Requirement is developed. It can be used for selecting appropriate arrangement of condenser and radiator and for determing their optimum operating parameters.

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.

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.

Military combat/tactical vehicles, such as tanks, are designed to be deployed and operated constantly in close proximity to the enemy fire. In order to provide sufficient protection for the engine and its vital systems, they are located in an almost completely enclosed and heavily armored compartment ventilated through highly restricted ballistic grilles. The space available for the cooling system in the engine compartment is limited. The heat rejection rate from various sources is high. The cooling air flow path is clumsy; repeated enlargements and reduction of the air flow sectional areas, complemented by possible bending and twisting, are common. The effective cooling air temperature is much higher than that of the ambient. All these factors alone make the cooling system designs of the subject vehicles quite different from that of the commercial vehicles, not to mention the severe military environment within which the cooling system must function properly.

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.