Abstract

Solar water heating systems with the flat-plate collectors are studied theoretically and experimentally. In theoretical part of this study, a forced circulation solar water heating systems is designed for domestic hot water requirements of a single family residential unit in Montreal. All necessary design parameters are studied and optimized using TRANSYS simulation program. The solar fraction of the entire system is used as the optimization parameters. The results show that by utilizing solar energy, the designed system could provide 85-100% and 30-40% of the hot water demand in summer and winter, respectively. The experimental part of this study is focused on the investigation of the effect of heat transfer augmentation devices inside the tubes of a flat-plate solar collector. An indoor experimental facility is developed, and different modules of flat-plate collectors with heat enhancement devices are designed and fabricated. Heat is provided by radiation and local temperature measurements were made at different locations inside and outside the collector over a range of Reynolds numbers from 200 to 5500 and two different incidents radiant heat fluxes. For the entire Reynolds number range, no appreciable heat enhancement is observed due to the heat enhancement devices. The analysis showed that in all cases, the free convection is the dominant mode of heat transfer compared to the forced convection. Thus, the turbulence production due to shear is suppressed by the thermal stratification in the flow. It is concluded that any method of heat enhancement by enhancing the shear-production of turbulence is ineffective in flat plate solar collectors