Optimized design and operation of heat-pipe photovoltaic thermal system with phase change material for thermal storage

This work aims to optimize the design and operation of a heat pipe photovoltaic-thermal (HP-PV/T) panel integrated with a phase change material (PCM) thermal storage water tank to produce electricity and hot water for an office building. A transient mathematical model for the integrated HP-PV/T-PCM system was used to predict its performance for known environmental and solar conditions and PCM melting point. The validated model was applied on a typical office space in the city of Beirut to obtain an optimal design using a derivative free genetic algorithm. The incremental system cost associated with a heat pipe and PCM tank was used in the optimization to obtain a design resulting in minimum annual auxiliary heating cost to meet the hot water demand while providing the electricity needs at a lower number of PV panels due to improved efficiency. An optimal system of 4 kW (20 PV panels each at 1.6 m2) was found to meet the electric power needs all year round. The optimal PCM storage tank size per panel was 37 l at PCM total mass of 22.42 kg with melting temperature of 33 °C.