Investigation of Thermal Performance of Finned,Water-PCM,Double Tube Heat Recovery


In this work, focus is taken on developing a waste heat recovery system for capturing potential of exhaust heat from an air conditioner unit to be reused later. This system has the ability to store heat in phase change material (PCM) and then release it to a discharge water system when required. To achieve this goal, a Finned, Water-PCM, Double tube (FWD) system has been developed and tested. Different profiles of fins attached to the (FWD) system have been investigated for increasing the thermal conductivity of the PCM. These include using Circular Finned, Water-PCM, Double tube (CFWD) system; Longitudinal Finned, Water-PCM, Double tube (LFWD) system; Spiral Finned, Water-PCM, Double tube (SFWD) system; as well as; Without Fins, Water-PCM, Double tube (WFWD) system. An experimental test rig that attached to an air-conditioner unit has been built to include 32 tubes of the FWD systems for both vertical and horizontal layouts during charging and water discharging processes. Transient 3-D, numerical simulations using (ANSYS Fluent14.0 software) have been developed to predict the thermal behavior for all types of FWD systems under investigation. Results show a significant performance improvement when using spiral and circular fins during charging process at vertical position. However, longitudinal and without fins showed better performance in horizontal position. Overall, SFWD system in vertical position has been found to exhibit the most effective type due to the fastest PCM melting and solidification. As compared to the WFWD system, the FWD systems have been found to increase the PCM temperature gain of about 15.3% for SFWD system; 8.2% for CFWD; and 4.3% for LFWD system. Also, comparisons between numerical and experimental results for both (measurement data and thermal camera photos) have been found reasonably matched.