Department of Physics and Electronics, North West University (Mafikeng Campus), Priv. Bag X2046, Mmabatho, 2735, South Africa; McPherso Academic Consulting, Postnet Suite 194, Private Bag X2230, Mafikeng South 2791, South Africa
Mawire, A., Department of Physics and Electronics, North West University (Mafikeng Campus), Priv. Bag X2046, Mmabatho, 2735, South Africa; McPherson, M., McPherso Academic Consulting, Postnet Suite 194, Private Bag X2230, Mafikeng South 2791, South Africa; van den Heetkamp, R.R.J., Department of Physics and Electronics, North West University (Mafikeng Campus), Priv. Bag X2046, Mmabatho, 2735, South Africa
A very small oil-in-glass tube thermal energy storage (TES) system is designed to allow for rapid heat transfer experiments. An electrical hot plate in thermal contact with a steel spiral coil (SSC) is used to charge the TES system under different hot plate temperatures and under different average charging flow rates. Thermal performance during charging is presented in terms of the axial temperature distribution, the axial degree of thermal stratification, the total energy stored and the total exergy stored. The energy and exergy delivery rates of the energy delivery device (EDD) are also evaluated in relation to the thermal performance of the storage system. Results of charging the storage system under different hot plate temperatures indicate that there is an optimal charging temperature for optimal thermal performance. The results also indicate that exceeding this optimal temperature leads to a degradation of the thermal performance due to increased heat losses. Charging at the same temperature conditions under different flow rate regimes suggests that there is an optimal charging flow rate. This optimal flow rate is a compromise between achieving a greater heat transfer rate in the EDD and achieving a greater degree of thermal stratification in the TES system. © 2009 Elsevier Ltd. All rights reserved.
Charging; Energy; Energy and exergy; Energy delivery; Glass tubes; Heat transfer rate; Hot plate temperature; Hot plates; Oil-in-glass tube; Optimal flows; Optimal temperature; Spiral coils; Storage systems; Temperature conditions; Thermal contact; Thermal energy storage systems; Thermal performance; Total energy; Exergy; Flow rate; Flywheels; Glass; Heat exchangers; Heat storage; Nanosensors; Optimization; Thermal energy; Thermal stratification; Tubes (components); Mixed convection; design; exergy; heat transfer; performance assessment; steel; storage; thermal power; Helicodiscus bonamicus