Solar cooling modelling utilising for cooling agro-products cold store under Rwandan environmental conditions

Abstract

Abstract: Solar-driven cooling systems can be considered as a sustainable solution for the weak cold chain. Transient Simulation System (TRNSYS) offers component-based 0D modelling capability of different engineering systems. TRNSYS has been employed to model a year-round performance of a PV solar-driven electric chiller to meet the cooling demand of post-harvested foodstuffs under Rwandan metrological data. Various PV module sizes and batteries storage capacities have been investigated to examine their effect on the solar energy fraction powering the electric chiller to maintain the room at the desired temperature. In addition, two different arrangements of chilled water loop, namely one-loop with 3 KW chiller capacity and two-loops with 6 KW chiller capacity have been compared to investigate their effect on the chiller performance and solar fraction. Results revealed that the later arrangement exhibits a higher solar fraction compared to one loop despite the addition of another pump. For 35 PV modules, the two-loops arrangement requires 42 kWh battery capacity to provide about 90% solar fraction, while one-loop needs 66 kWh to deliver the same solar fraction. Accordingly, the battery storage capacity is reduced by a factor of 0.36 which justifies the increase in the chiller capacity from 3 KW to 6 KW. This study provides a selection map to choose between the number of PV panels and batteries capacity required to power the chiller and meet the cooling load.