Wind power generation and integration into a low-cost fresh produce preservation technology: a case of a renewable energy integration into an evaporative cooling system.

Abstract

Smallholder farmers in developing countries experience high-postharvest losses (PHL) estimated around 23% during the transportation of fruit and vegetables. This is due to the inappropriate storage facilities that are unable to maintain optimum environmental conditions which are specific to the fresh produce. This situation arises because smallholder farmers cannot afford the available mobile cooling technologies such as refrigerated trucks since they are energy-intensive which makes them have high running costs in addition to the associated high investment costs. Consequently, smallholder farmers resort to utilizing small vehicles to transport fresh produce without air conditioning to cool the environment. These vehicles usually have an environment mainly characterized by high temperature and low relative humidity which are undesirable conditions for fresh produce. The power supply is a great challenge for mobile cooling technologies. As the main energy source, mobile cooling technologies use petrol and diesel to power the systems. These energy sources are costly, rapidly depleting, and detrimental to the atmosphere. Renewable energy sources such as biomass, solar and wind energy are promising technologies to substitute fossil fuels to power cooling technologies. Using renewable energy sources reduces the high incurring costs of operating a cooling technology, which ultimately reduces the purchase or lease costs. Since there is high airflow on the road associated with moving vehicles, this study aims to design and develop a small wind turbine to power an evaporative cooling system (ECS) during the transportation of fruit and vegetables in KwaZulu-Natal. The design of the wind turbine is done with the assistance of the Blade Element Momentum (BEM) theory, QBlade and MATLAB Simulink modelling software. A prototype of the wind turbine was designed, developed and tested on a moving vehicle between Pietermaritzburg and Estcourt. The wind turbine is 600 mm in diameter and made of three PVC pipe material blades connected by a 60 x 2 mm diameter mild steel plate hub protected by an 800 x 800 x 500 mm mild steel protective casing.The wind turbine was tested against three vehicle speeds of 60, 80, and 100 km.h -1 , and the two opening levels, level 1 at 45° and level 2 at 80° relative to the louvre mechanism frame. The results of this study revealed that the power output is significantly influenced (p<0.001) by both the vehicle speed and louvre opening level. The power output of 113.4, 159.6 and 210.0 W per hour was observed for the vehicle speed of 60, 80 and 100 km.h -1 , respectively, on louvre opening level 1. Further, the power output of 142.8, 268.8 and 294.0 W per hour was observed for a wind speed of 60, 80, and 100 km.h -1 , respectively on louvre opening level 2. This shows iv that higher wind speeds (vehicle speeds) obtain higher power output which account for the small size of the wind turbine rotor. The maximum power of 294 W was obtained at a vehicle speed of 100 km.h -1 (27.78 m.s -1 ), for louvre opening l...