Thermal booster on the performance of heat pipe evacuated solar tube collectorThermal booster on the performance of heat pipe evacuated solar tube collector
The research aims to investigate the possibility of enhancing the functionality of a heat pipe evacuated tube collector with a new method of, one or both an evacuated tube and two separate storage tanks, incorporating nano or micro-enhanced phase change materials as a thermal energy storage system. In the proposed systems, the evacuated tube was filled with enhanced medical paraffin wax, while the two separated tanks were filled with enhanced paraffin wax (grade-A). These two types of paraffin wax were enhanced with 5wt% CuO nanoparticles (NP-CuO) or ZnO microparticles (MP-ZnO). In this study, six tests were carried out to do the investigation. Three tests were done to investigate the effect of the integration of enhanced-phase change material in the only evacuated tube of the heat pipe evacuated tube collector. The other three tests were performed to investigate the effect of enhanced-phase change material integrated into both the evacuated tube of the heat pipe tube collector and two additional storage tanks. The main advantage of this new system is that it improves solar water heater efficiency by minimizing hot water temperature fluctuations. Thereby, the efficient thermal isolation of the evacuated tube and storage tanks and the efficient energy accumulation in phase change material enables the system to supply hot water even when there is no solar radiation at night or in overcast weather. The results showed that the integration of enhanced-paraffin wax with NP-CuO and MP-ZnO in both the evacuated tube and the separated tanks gives an efficiency improvement range of (36.8-50%) and (25.43-41.4%) respectively, While the integration of enhanced-paraffin wax with NP-CuO and MP-ZnO in the only evacuated tube led to an increase in the efficiency with a range of (33.8-45.7%) and (23.8-26.7%) respectively
This work presents the possibility of enhancing the functionality of a heat pipe evacuated tube collector by the integration of nano CuO or micro ZnO-enhanced paraffin wax as a thermal energy storage system into one or both the evacuated tube and two separated storage tanks. So, three tests were conducted to investigate the integration of enhanced paraffin wax into only the evacuated tube with water flow rates (1, 2, and 3L/h). Three tests with the same water flow rates were done to investigate the integration of enhanced paraffin wax into both the evacuated tube and two separated storage tanks.
The following conclusions were obtained:
• Integrating pure or enhanced phase change material into both the evacuated tube and the two separated tanks significantly reduced the disadvantages of overheating heat pipe compared to the commercial phase change material-free solar collector.
• By the improvement in the thermal conductivity of paraffin wax, the addition of NP-CuO and MP-ZnO reduced the melting time of the paraffin wax by about 1 and 0.5h, respectively.
• The addition of NP-CuO and MP-ZnO into the paraffin wax integrated into the evacuated tube only led to an increase in the supplied hot water period from the collector by about 5 and 6.2h, respectively higher than the phase change material-free typical collector.
Author
Dr.P.K.Sharma
Principal, NIRT