Response Surface Optimization of Convective Air Drying Process in a Hybrid PV/T Solar Dryer

Year 2020, Volume: 1 Issue: 1, 111 - 130, 30.06.2020

Sampson Uzoma Nnaemeka Nwakuba , Kelechi Anyaoha

Abstract

The increasing demand for improved techno-economic and efficient drying systems has impelled research on optimization study of solar drying process. This paper discusses the optimization of red pepper slices during drying process in a hybrid photovoltaic-thermal (PV/T) solar dryer using response surface approach. The study was conducted in humid tropical Nigerian environment characterized by intermittent solar irradiance, prompted by humid wind effect from regional water bodies. The effects of varying drying air temperatures (50, 60 and 70oC), air velocities (1.0, 1.5 and 2.0 m/s), and sample thicknesses (10, 15, and 20 mm) on the total energy consumption, drying efficiency, %shrinkage, and drying time of pepper samples were investigated using a 33-factorial treatment design. The results obtained were built-in and the responses plotted in 3-D surface plots and evaluated statistically to obtain variable relationships. The total and specific energy consumption ranged between 1.31 – 38.9 kWh and 6.92 – 62.76 kW/kg, respectively. The mean system drying efficiency varied between 6.73 - 35.14%, whereas the percentage shrinkage ranged between 56.91 - 73.90%. The drying time varied from 125.5 ± 7 - 205.5 ± 10 mins. At the optimum drying conditions of 70oC air temperature, 1.88 m/s air velocity and 14.31 mm sample thickness and desirability of 0.903, the total energy consumption, drying efficiency, shrinkage, and drying time were obtained as 4.03kWh, 20.46%, 67.05% and 183.8 mins, respectively. The predicted models had R2-values ranging between 0.9228 - 0.9989, which were verified and validated for accuracy using diagnostic plots and percentage error deviations. The results of this study indicate how indispensable some variables and process conditions are to the performance of hybrid PV/T solar dryer.

Keywords

Photocell, vegetables, energy, efficiency, product quality

Supporting Institution

Imo State Polytechnic, Umuagwo-Ohaji, Nigeria

Project Number

TETFund/RP/Imopoly/2018-2019

Thanks

TETFund and Imo State Polytechnic, Umuagwo-Ohaji for sponsoring this research.

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