Study the flow direction and number of tubes in cross-flow heat exchanger to improve the heat transfer coefficient.

Abstract

This study deals with the effects the number of tubes and flow direction on the heat transfer coefficient. This investigation complete by study different lengths of smooth copper tubes (50,100, 150, 200 and 250) mm with different passes (2, 4, 6, 8 and 10) for cross flow heat exchanger to attain the best length to heat transfer numerically, by Solid work 2017 and ANSYS 16.1 program. The diameters of outer and inner tubes are (24 and 19 mm), air velocity (3 m/s), volumetric flow rate (5 L/min) and the inlet temperature of cold and hot fluid (25 °C and 80°C) respectively. Also been studying the effect of a smooth and triangle finned tube (4 passes) to enhance the heat transfer. Moreover, studying the effect of up and horizontal direction of the flow on heat transfer, by designing smooth tube 8 passes heat exchanger with the same dimension, air velocity inlet (1 m/s), volumetric flow rate (6 L/min), the temperature of the cold fluid inlet (22 °C) and the temperature of the hot fluid (50 °C). It can be noted that whenever the number of passes of tubes increases, the amount of heat transfer increase at the expense of the increase in pressure drop. The finned tube gives better heat improvement than a smooth tube and the direction of flow does not effect on the heat transfer.