Performance of hybrid photovoltaic/thermal crop dryer in hot humid Nigerian region

Abstract

This paper presents a study carried out to investigate the performance of a hybrid photovoltaic/thermal crop dryer in hot humid region of Umuagwo-Ohaji in the South-east region of Nigeria, through energy and exergy analyses, drying, electrical and thermal efficiencies, energy utilization and energy utilization ratio, sustainability indicators such as waste energy ratio (WER), sustainability index (SI) and improvement potential (IP). Drying experiments were conducted at varying inlet air temperatures (50, 60 and 70 o C), airflow rates (1.14, 2.29 and 3.43 kgs -1 ) and slice thicknesses (10, 15 and 20 mm) on 500g batch size of red pepper slices during sunshine periods. Results obtained show that the total and specific energy consumption for drying a batch of sliced red pepper samples varied between 2.08 – 34.91kJ and 7.04 – 62.76 kJkg -1 , respectively. The energy utilization and energy utilization ratio during the drying process ranged from 195.75 – 3013.21 Js -1 and 1.82 – 20.4%, respectively. The energy and exergy efficiencies varied between 15.6738.17% and 26% to 88%, respectively. The mean drying efficiency of the system ranged from 7.12 – 40.27%. The maximum electrical and thermal efficiencies of 23.86% and 93.03%, respectively were obtained. A waste energy ratio of 0.0827 0.1579 was obtained, whereas SI and IP values ranged between 1.137 ≤ SI ≤ 6.119 and 0.198 ≤ IP ≤0.583kW, respectively. There is certainly a wide range of improvement in the PV/T system as 12.1 – 18.4 % of the solar irradiance was consumed for drying. Prospects for improvement and recommendations for further studies were suggested.