Experimental investigation on the performance of parallel and staggered arrays of PCM energy storage system for PV thermal regulation

Abstract

A thermal energy storage system of phase change material (PCM) used for enhancing thermal regulation of photovoltaic (PV) system is experimentally investigated. The storage system consists of heat storage battery made of an acrylic heat exchanger (HE) and copper tubes row of encapsulated PCM type RT 44HC. The PCM system is coupled with a thermal water bath representing PV heat source. The heat storage capacity and heat storage rate for the encapsulated PCM plus the heat transfer parameters between the heat transfer fluid (HTF) and PCM including Nusselt number and heat transfer coefficient are analyzed. Charging and discharging cycles of the PCM between 25 °C and 49 °C for the different patterns for the encapsulated PCM system are evaluated and analyzed at three volume flow rates of 0.5, 1, and 2 L/min. Results show that the proposed system achieves the best performance for the staggered alignment compared to the parallel despite that it shows a weakness in the horizontal position. The PCM average charging rate in the staggered case is 73, 83, and 88 kWh at 0.5, 1, and 2 L/min volume flow rates, respectively. The highest instantaneous heat storage capacity for the charging and discharging cycle is achieved during the parallel alignment with a volume flow rate of 0.5 L/min. The average heat transfer coefficients during the charging cycle for the parallel alignment are 49, 72, and 113 W/m2.°C while these values are improved by 57%, 104%, and 130% for the staggered case for 0.5, 1, and 2 L/min volume flow rates, respectively. The proposed system allows utilization of the stored heat from the PV system for different applications. Manipulation between different charging and discharging rates allows fast response and economic performance during operation.