Performance analysis of different U-shaped heat exchangers in parabolic trough solar collector for air heating applications

Abstract

In this article, the thermal performance of a parabolic trough solar air heater (PTSAH) with a U-shaped heat exchanger is evaluated. The solar air heater's performance is examined by using the copper and aluminum U-shaped heat exchangers (UHX) with and without fin alternately, inside the absorber tube placed at the focal length of the nickel-coated stainless steel parabolic trough. The system is examined in the form of temperature difference achieved at the outlet for both the heat exchangers and the solar air heater's efficiency. It is observed that the system performance with the copper heat exchanger is better than the aluminum heat exchanger. Further, it has been found that the efficiency of the solar air heater is increased by 9.29% at a high flow rate with the use of fin when using a copper heat exchanger in place of the aluminum heat exchanger. The temperature difference achieved by the system is also increased by 2.34% at a low flow rate. At elevated temperatures, the percentage increase in solar air heater performance for the aluminum heat exchanger is higher than the copper heat exchanger.