The effect of the intermediate fluid-flow rate on the system performance in the closed circuit applications of the solar collector

Solar collector water heating system use solar thermal energy to provide hot for domestic and industrial use. These systems are operated either as open-loop or closed-loop flow circuit. The former loop not recommended the cold climates having freezing problem. Although previous studies on collectors have used operation with working fluid. However, it must high boiling low points colder regions thus arises need antifreeze mixtures of water. Another solution same problem is heat transfer oil intermediate fluids. In present study, exergy analysis a boiler supported vacuum tube in different fluid-flow rates been performed evaluated. Heat has an fluid closed at 0.277 kg/s, 0.383 0.494 kg/s. results show that temperature difference well outlet decrease. inlet increases by increasing rate. Moreover, increase rate, was ascertained efficiency increase. main finding study closed-circuit direct effect