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A 2D analysis of the solar air collector of an indirect solar dryer with pentagonal corrugation on the absorber plate was carried out using ANSYS Fluent 16.0 to enhance the performance. SIMPLE algorithm and RNG k-ε model were used for resolving the governing expressions. Corrugation pitch (p), height (e), angle (α) and Reynolds number (Re) were considered as design parameters for the analysis. The p was varied from 50 to 175 mm and an optimized p value was proposed. The Re range used was 1800 15,000. The velocity, velocity vector, and turbulent kinetic energy were presented. Performance characteristics such as Nusselt number (Nu), friction factor (f), Nu ratio, f ratio and thermo-hydraulic performance parameter (Thpp) were determined and compared for different p and Re. The Nu ratio obtained was 1.81–2.88 and it was proved that corrugation gives a maximum of 2.88 times heat transfer enhancement than a flat plate. Maximum Thpp was found to be 1.748 and was obtained at p = 150 mm and low Re (1800). The proposed optimum pitch was 150 mm (relative roughness pitch, p/e of 15). The outcomes of the present analysis were validated with existing publications and found that the results are comparable. [ABSTRACT FROM AUTHOR]

Solar updraft tower (SUT) plant is one of the viable passive energy technologies for carbon-free power generation. However, the lower thermal performance of the plant is still a major huddle for its global acceptance. The main aim of the present study is to improve the performance of the plant by providing guide vanes inside the canopy. A SUT plant was developed, where the height of the chimney, collector inclination angle and diameter of collector were 6 m, 30° and 3.5 m, respectively. The flow and performance parameters of the plant were measured and analyzed. Two distinct scenarios such as Case1: the SUT plant and Case2: Case1 with guide vanes were studied. It was observed that the flow and performance of the system were enhanced significantly in Case2 compared to Case1. The maximum hourly average velocity at chimney base and maximum theoretical power potential were enhanced by 9.4 and 10.7%, respectively, at 13.30 h for Case2. For the study period of 13 h, the overall efficiency of the SUT system was enhanced by 46.7% in Case2 compared to Case1. [ABSTRACT FROM AUTHOR]

The effect of integrating thermal energy storage (TES) unit with a natural convection indirect type solar dryer was investigated by drying ivy gourd in the dryer without TES (setup I) and with TES (setup II) provisions. Paraffin wax was filled in the concentric tubes of polycarbonate and finned aluminum to make setup II by updating setup I. The experimental data from both setups were used to estimate the drying parameters. The average collector's efficiencies were 62.6% and 63.3%. Drying efficiencies were 6.6% and 13.1% for the setup I and II, respectively. The average moisture diffusivity, mass transfer and heat transfer coefficients were 7.1 × 10−9 and 8.1 × 10−9 m2/s, 0.0033 and 0.0041 m/s and 3.9 and 4.7 W/m2K for the setup I and II, respectively. The enhancements of drying efficiency, effective diffusivity, mass and heat transfer coefficients were 98.3%, 14.2%, 24.2% and 22.1%, respectively, in setup II compared to setup I. The activation energy, average specific energy consumption, and specific moisture extraction rate were evaluated. The drying kinetics were correlated with time and moisture variations. It took 18 and 16 h to reduce the moisture content of the sample from 15.32 (db) to 0.144 (db) for the setup I and II, respectively. [ABSTRACT FROM AUTHOR]