Improving the thermal efficiency in heat exchangers of transport vehicles

Abstract

The heat exchangers are widely used in the cooling and heating system of transport vehicles. Therefore, enhancement of thermal efficiency of heat exchangers can lead to energy savings of transport vehicles. To increase the efficiency of heat transfer equipment, different methods of enhancement of heat transfer are widely used. However, when methods of enhancement of heat transfer employed, hydraulic resistance also increases. Thus, to evaluate the effectiveness of the method of enhancement of heat transfer, thermal efficiency is used. In this paper, we consider the effect of tube pitch with a different configuration of tube bundles on the thermal efficiency of enhancement of heat transfer by pulsating flows. Results obtained for four typical tube array arrangements (triangular staggered, rotated triangular staggered, rotated square staggered, square inline). The tube pitch ratio of the tube bundle was 1.25, 1.5, and 1.75. Results presented the effect of pulsations in tube bundles on the thermal performance ratio at the same Reynolds numbers and thermal performance ratio at the same power required for pumping the coolant in steady and pulsating flow. It is found that the change in tube pitch has a different effect when the thermal performance ratio was evaluated with the same Reynolds number and at the same power required for pumping. With an increase in tube pitch, the thermal performance ratio at the same Reynolds numbers can either decrease or increase depending on the tube array arrangements and parameters of the pulsating flow. Higher values on the thermal performance ratio at the same Reynolds numbers and at the same power are mainly observed for the square inline array, which may change depending on the tube pitch and parameters of the pulsating flow. The maximum value of the thermal performance ratio at the same Reynolds numbers was 0.623 at the tube pitch of 1.25 and square inline array. The maximum value of the thermal performance ratio at the same power was 1.92 for tube pitch of 1.75 and square inline array.