Evaluation of Heat Transfer Parameters of the Car Engine Cooler with the External Heat Exchange Surface Clogged by Silt Soil

The paper focuses on the evaluation of heat transfer parameters in the cooling of the engine cooler clogged with silty soil at the levels of 25%, 50%, 75%, and 100%, compared to the unclogged cooler. The influence of the percentage of clogging in the fin-and-tube cooler is evaluated based on the cooler’s inlet and outlet temperatures, the heat transfer rate on both the coolant and air sides, the average heat transfer coefficient and Nusselt number, the overall heat transfer coefficient, and the air-side fouling resistance. As the percentage of cooler clogging by silty soil increased, the values of Rfa and Ts,avg also increased, while the heat transfer from the surface to the ambient environment decreased. The unclogged cooler achieved 1.07, 1.11, 1.15, and 1.16 times higher total heat transfer coefficient values compared to the 25%, 50%, 75%, and 100% clogged coolers. At the time of 90 s, the fully clogged cooler achieved a 1.9-times decrease in the heat transfer rate on the coolant side compared to the unclogged cooler. There is an inverse correlation between the Nusselt number and air-side fouling resistance, which means that an increase in the percentage of cooler clogging by silty soil caused a decrease in heat transfer and hence an increase in thermal resistance.