Enhancement of an air conditioning system performance utilizing a PCM-based heat exchanger: Impact of aspect ratio

Abstract

This research emphasizes enhancing air conditioning (AC) system performance through the integration of a phase change material (PCM)-based annulus heat exchanger (HEX) within the condenser unit. The present study delves into how aspect ratio (AR), inlet velocities, and inlet air temperature impact the coefficient of performance (COP) and melting rate. Moreover, it considers the variable specific heat of the PCM, a less-explored aspect in AC-integrated PCM systems. Results have revealed that the AR notably affects the complete melting time. Specifically, an increase in the AR from 15 to 21 has led to a noteworthy reduction of 30.07% in the total melting time under fixed velocity conditions at 2.55 m/sec and θ = 0.429. The present study has also established a correlation to demonstrate how total melting time is influenced by AR, inlet air temperature, and inlet velocity. Also, modifying AR and inlet velocity to the HEX could lead to lower outlet temperatures from the HEX. Initially, at a given velocity of 2.55 m/sec and θ of 0.429, increasing the AR from 15 to 18 leads to a 1.61% decrease in the outlet air temperature from the HEX, while increasing AR from 15 to 21 results in a 3.12% decrement. PCM-enhanced AC systems consistently exhibit improved COP values, especially in low-velocity scenarios, outperforming systems without PCM. At the onset of melting, for a given velocity of 2.55 m/sec and θ of 0.429, the percentage increase in the COP for the altered system compared to a system without the PCM is found to be 11.28%, 12.84%, and 14.01% for ARs of 15, 18, and 21, respectively. Configurations with higher ARs are found to be more suitable for higher cooling loads with shorter working periods.