Latent heat storage using paraffin in an eccentric annuli of horizontal tube-in-shell unit

Interest on renewable energy sources and energy storage have increased recently because of dramatic increase in the consumption of conventional energy sources and their hazardous effects on environment. Thermal energy storage plays an important role in conservation of available energy and eliminating the phase lag between energy supply/availability and demand. An experimental study is conducted in order to investigate the melting (charging) and solidification (discharging) processes of a phase change material (PCM) in a tube in shell heat exchanger system. Paraffin is used as PCM while water is as heat transfer fluid (HTF). The PCM was stored in the horizontal annular space between an inner tube and outer shell. The inner tube has been settled in four different position; one is concentric (e=0 mm) while the others are eccentric (e=10, 20, 30 mm). Experiments are conducted both for charging and discharging processes. For each geometrical configuration, experiments are carried out of a constant value of mass flow rate and three different values of inlet temperature of HTF. It has been shown that eccentricity shortens the melting time for the charging process, while it makes the solidification time longer for the discharging process. Key Words: Thermal energy storage, Phase change materials, Paraffin, Melting, Solidification, Eccentricity.