Effect of helical diameter on the performance of shell and helical tube heat exchanger: An experimental approach

In the present paper, shell and tube heat storage unit (HSU) with spiral tube is filled with phase change material (PCM) is experimentally investigated. Paraffin RT-35 is used to fill the HSU and water is chosen as HTF (heat transfer fluid). Performance of HSU is examined for Stefan numbers of 0.43, 0.48 and 0.53. Volume flow rate of HTF is 500ml/min. In order to evaluate the effect of helical diameter on performance of HSU three diameters 5, 7 and 9 cm are utilized. Results show that by increasing of Stefan number melting process accelerates and total melting time decreases. Results also indicate that increasing coil diameter causes a decrease in total melting time and also an increment in final average temperature of PCM. Absorbed energy by PCM is increased by increasing helical diameter of HTF tube.