Computational Study of Hybrid Water Heater with Evacuated Glass Tube Solar Collector and Rice Husk Combustion

Problem statement: The thermal performance modeling of hybrid water heater with evacuated glass tube solar collector and flue gas of rice husk combustion was developed. The solar global radiation and ambient air temperature data used in the system modeling belongs Phitsanulok province from 7 am-5 pm in the summer season. Approach: The system can be divided into two parts, i.e., evacuated glass tube thermosyphon solar collector and thermosyphon heat exchanger with flue gas of rice husk combustion. The evacuated glass tube was a coaxial double-layer tube made of Borosilicate. Its outer tube diameter and inner tube diameter were 58 and 47 mm respectively. The inside cavity of evacuated glass tube holed thermosyphon which was made of copper tube and filled with R134a at the filling ratio of 70% of evaporator volume. For latter, the temperature and flow rate of flue gas that was released from the cyclone furnace and used as a heat source of heat exchanger were constant at 150°C and 50 m³ min^-1. The heat exchanger was consisted of array of thermosyphon which was made of stainless steel tube and filled with distilled water at 50% filling ratio of evaporator volume. Results: The effects of various parameters on the system performance were computational analyzed. The hybrid water heater system with optimum design of both thermal performance and economic can be obtained and produce the hot water at the temperature exceeding 70°C and the flow rate of 1 m³ day^-1. Conclusion: The thermal performance of this optimum hybrid water heater system was investigated along the time of the day in summer.