Effects of spring turbulators in the annular heat exchangers on the heat transfer and pressure losses

Heat exchangers are one of the most important devices of industry and they can have various type and capacity ranges, and can be seen in chemical industry, thermal centrals, cooling, heating and ventilating processes calling as evaporator, condenser, heater, refrigerator etc. Efficiency analysis of these commonly used devices should be done and for energy saving, and hence their efficiencies should be made higher. The most efficient method for increasing the efficiency is to increase the heat transfer coefficient. In present work, various size and number of springs are located through an annular pipe, of which outer surface is heated by steam vapor, in order to increase the heat transfer ratio. The location type of the springs, number of the springs and diameter of the springs are varied in the tests. The working fluid is air and Reynolds number of the air is varied from 2500 ? Re? 12000. Heat transfer, pressure loss, and exergy analysis for the pipe with turbulators (with springs) and without turbulators (without springs, empty pipe) are calculated. New empirical correlations are obtained and the results are compared to each other and literature. Keywords: heat exchanger, turbulators, heat transfer, exergy