Experimental study of the phase change heat transfer inside a horizontal cylindrical latent heat energy storage system

• Experimental study of the phase change heat transfer inside a cylindrical latent heat energy storage system.
• Both charging (melting) and discharging (solidification) experiments were performed.
• During charging, natural convection is the dominant mode of heat transfer once enough liquid melt is present.
• During discharging, conduction is the only mode of heat transfer, requiring the design and addition of fins.
• The heat transfer fluid inlet temperature greatly affects the overall charging and discharging process within the system.

This paper presents an experimental study of the phase change heat transfer inside a cylindrical latent heat energy storage system (LHESS), designed with a central finned copper pipe running the length of the cylindrical container, during charging and discharging operations. Longitudinal fins were added to the copper pipe to enhance the overall heat transfer rates during the phase change processes; fins with two orientations, straight fins and angled fins, are used. The phase change material (PCM) used is dodecanoic acid. The experimental work concentrates on studying the heat transfer mechanism during melting and solidification of the PCM, impacts of the heat transfer fluid (HTF) inlet temperature and HTF flow rates. Moreover, heat transfer enhancement effectiveness of straight fins and angles fins configurations is compared. It is observed that conduction is the dominant heat transfer mechanism during the initial stage of charging, and natural convection dominates once enough liquid PCM is present inside the system. Conduction dominates during the entire solidification process. Complete melting time is strongly affected by the HTF inlet temperature but very slightly by the HTF flow rates.