Numerical and Experimental Investigation on a Combined Sensible and Latent Heat Storage Unit Integrated With Solar Water Heating System

Abstract

The present work investigates, theoretically and experimentally, the thermal performance of a packed bed combined sensible and latent heat storage unit, integrated with the solar water heating system. A one-dimensional porous medium approach with the finite difference technique is used to develop the numerical model to obtain the temperature profiles of both the phase change material (PCM) and heat transfer fluid (HTF), and the molten mass fraction of the PCM at any axial location of the cylindrical storage tank during the charging process. The model also incorporates the effect of the varying fluid inlet temperature to accommodate the actual conditions that prevails in the solar collector. Experimental apparatus utilizing paraffin as PCM, which is filled in high-density polyethylene spherical capsules, is constructed and integrated with a solar flat plate collector to conduct the experiments. The water used as HTF to transfer heat from the solar collector to the storage tank also acts as a sensible heat storage (SHS) material. The results of the numerical model are compared into the experimental results of the temperature profile for various porosities and HTF flow rates. It is found that the results of the numerical model are in good agreement with the experimental results. The performance parameters, such as instantaneous heat stored, cumulative heat stored, and charging rate are also studied in detail.

Effect of Swirl Flow Injection on Latent Heat Dispersion of Spherical PCM Capsules with MWCNT Fillers

“…For the maximum flow rate of 3 l/min, the total charging time of latent TES system with respect to injection pressure of4 bar was found to be 35 mins. In general, in a sensible heat TES system, the storage capacity increases with increase in HTF inlet temperature, the total charging time will remain the same for a given flow rate, in the case of an adiabatic TES system [25]. However, in the present case, the increase in charging time with reduction in HTF flow rate in the latent heat TES system is attributed to increased losses due to mixing and improper insulation of the storage tank.…”

Review of the application of phase change material for heating and domestic hot water systems

“…The findings indicate that melting and freezing rates are significantly lower for capsules with large radii than for those with smaller radii. Nallusamy and Velraj [81] experimentally and numerically investigated a packed bed composed of sensible and PCM thermal energy integrated with DHW system. A cylindrical tank integrated into a solar flat plate collector was filled with polyethylene spherical capsules.…”

Numerical investigation of packed bed storage unit filled with PCM encapsulated spherical containers – A comparison between various mathematical models

“…They have reported the effect of porosity and various non dimensional parameters and conclude that Ste (0.2e0.4), porosity (0.4e0.49) and St (0.7e1.0) are to be chosen for higher and faster energy storage. Nallusamy et al [11] have also investigated the performance of the similar storage unit for solar water heating applications using the same mathematical model. However, their model also accommodates the effect of varying inlet temperature to the storage tank to simulate the hot water coming from the solar collector.…”