Energy and exergy analysis of conventional and modified flat-plate solar collector with dual spiral flow tubes: A comparative study

The most fundamental collectors for water heating are flat plate solar collectors (FPSCs). They are inexpensive, simple to build, and need little maintenance. Conventional FPSCs have relatively low efficiency. More study is needed to increase the efficiency of FPSC by using novel designs. To enhance thermal performance, various strategies have been implemented through design modifications of flow tubes. In this study, dual spiral-shaped flow tubes were constructed instead of the usual FPSCs number of riser tubes and headers and tested with three different mass flow rates (20.9, 29.9, and 42.1 l/h). The optimum instantaneous efficiency achieved is 70.8% at a flow rate of 42.1 l/h, representing a 13.7% improvement in efficiency compared to the conventional collector and lowering the mass flow rate results in an enhanced exergy efficiency of 3.51% at 20.9 l/h. The modified collector achieves its highest instantaneous efficiency when the outlet water temperature is measured at 53.4 degrees C. The modified collector boosts heat transfers by enlarging the water's surface contact area and prolonging its flow time, resulting in greater heat absorption and significantly improved efficiency. When all other parameters are kept the same as in a conventional design, highly encouraging results in a modified collector have been recorded.