Effect of position of heat transfer fluid tube on the melting of phase change material in cylindrical thermal energy storage

ABSTRACT

The influence of the orientation of heat transfer fluid tube inside the horizontal cylindrical phase change material based thermal storage is experimentally investigated. The storage container is made up of a polycarbonate tube and filled with paraffin wax as a storage medium. The operating parameters are the fluid inlet temperature and flow rate. The fluid is water and the flow tube are made up of copper. The HTF is used at a temperature of 60°C and a flow rate of 2, 4 and 6 kg/min to charge the PCM. In the horizontal configuration, the angular HTF is observed with the 21.42% lesser charging time compared with the concentric configuration at the HTF flow rate of 2 kg/min. Thus, the effect of orientation of HTF tube is beneficial to achieve the faster charging of PCM for the solar thermal collectors which are operating at the intermittent solar radiations.

KEYWORDS:

• Heat storage
• melting time
• cylindrical storage
• phase change material
• inclined tube
• concentric tubes

Abbreviations

HTF Heat transfer fluid

LHS Latent heat storage

PCM Phase change material

TES Thermal energy storage

Nomenclature

$C_{pw}$ Specific heat of HTF [Jg⁻¹K⁻¹]

$C_{pcm}$ Specific heat of PCM [Jg⁻¹K⁻¹]

H Phase change enthalpy [Jg⁻¹]

$\dot{m}$ Mass flow rate of HTF [kgs⁻¹]

m Mass of PCM [kg]

Q_u Heat transfer rate [W]

T_i Initial temperature [K]

T_f Final temperature [K]

T_o Outlet temperature [K]

Tm Melting temperature of PCM [K]

t Time taken [min]

ΔTw Difference between inlet and exit temperature of heat transfer fluid [K]

ΔTw Difference between initial and final temperature of heat storage material [K]

Additional information

Notes on contributors

Ramalingam Senthil

Ramalingam Senthil obtained his B.E. (Mechanical Engineering) and M.E. (Energy Engineering) from the University of Madras (1997) and Anna University (2000) respectively. He received PhD (Solar Energy) from SRM Institute of Science and Technology (SRMIST), Chennai (2017). He has two decades of experience in teaching and research. He is working as Associate Professor at SRMIST, Chennai since 2005. The major research area is solar energy conversion and storage. He is a member of ASME, ISES, SESI and ISTE.