Numerical investigation of V-groove air-collector performance with changing cover in Bangi, Malaysia

Abstract

Air-based solar collectors are the simplest forms of flat plate solar collectors; without complications of introducing water or nanofluids into the process. They are used to raise the entering atmospheric air temperature to a level where it can be used for different low and medium temperature applications. The main components of their design are the collector, absorber and airflow arrangement. However, they exhibit the lowest efficiencies among other collectors. Hence, V-groove absorber designs are implemented to raise the thermal efficiency of air collectors. In this paper, a parametric study on the thermal performance of single-pass solar air collector with a v-groove absorber has been conducted using theoretical model and ran numerically using an excel sheet. The v-groove will enhance the convective heat transfer of the collector; as it has superior performance to flat-plate collectors. Two different cover designs are proposed; one with glass cover and the other with Fresnel lens cover. A comparison of different parameters is presented for various design conditions and operating conditions to drive the efficiency with respect to mass flowrate and incident solar radiation. This paper differs from other works in the literature in that it presents comparison between Fresnel lens and glass cover for V-groove single pass air heater. The results obtained shows that at solar irradiance of 755 W/m2 the collector covered with Fresnel less has the highest efficiency value of 71.18% compared to solar collectors with glass which has efficiency 54.10%. The mass flowrate contributed to efficiency enhancement. Moreover, a case study for Bangi, Malaysia was conducted to numerically test the performance of the two types using real-data from an outdoors test. Highest achieved temperatures from both collectors were around 35.85 °C for the glass-covered type and 38.39 °C for the Fresnel lens covered type. Keywords: Air-collector, Glass cover, Fresnel lens cover, V-groove, Convective heat transfer