Exergy analysis of vacumm tube solar collectors with a boiler according to different parameters

In this thesis, the energy and exergy analysis of boiler-supported solar vacuum tubes at different operating flow rates were done and evaluated with respect to different intermediate fluids. In a closed-circuit experimental system the heat transfer oil and 40% antifreeze-water mixture were used as two different intermediate fluids. These different intermediate fluids were circulated at three different operating flow rates in the closed circuit experimental system. The experiments were done at 0,277kg/s, 0,383kg/s and 0,494 kg/s flow rates, respectively. It was observed that with an increase in flow rate in the experimental system; collector inlet temperature increased, but, collector temperature difference (difference between inlet and outlet temperature) and outlet temperature decreased. During the experiment, with an increase in the flow rate; the sytem and the collector energy and exergy effiencies increased. It was also observed that the collector energy and exergy efficiencies of the heat transfer oil was much better than those of 40% antifreeze-water mixture. However, from system efficiency point of view 40% antifreeze-water mixture of the system gave better results compared to those of the heat transfer oil.