Comprehensive thermodynamic analysis of a renewable energy sourced hybrid heating system combined with latent heat storage

Abstract

In this study an experimental thermal investigation of hybrid renewable heating system is presented. Latent heat storage stores energy, gained by solar collectors and supplies medium temperature heat to heat pump both day time also night time while solar energy is unavailable. In addition to this an accumulation tank exists in the system as sensible heat storage. It provides supply–demand balance with storing excess high temperature heat.Analyses were done according to thermodynamic’s first and second laws by using real data obtained from a prototype structure, built as part of a project. Results show that high percent of heat loses took place in heat pump with 1.83kW where accumulator-wall heating cycle followed it with 0.42kW. Contrarily highest break-down of exergy loses occur accumulator-wall heating cycle with 0.28kW. Averagely 2.42kW exergy destruction took place in whole system during the experiment. Solar collectors and heat pump are the promising components in terms of exergy destruction with 1.15kW and 1.09kW respectively. Exergy efficiency of system components, investigated during discharging period are in a close approximately of 32%. However, efficiency of solar collectors and charging of latent heat storage are 2.3% and 7% which are relatively low. Average overall total energy and exergy efficiencies of latent heat storage calculated as 72% and 28.4% respectively. Discharging energy efficiency of latent heat storage is the highest through all system components. Also heat pump has a significant efficiency which is 78%.