Development of a computer model simulation for predicting the performance of a near infrared reflecting charcoal cooler for on farm storage of mangoes

Abstract

Mango (Mangifera indica L.) fruit is a valuable fruit in Kenya due to its nutritive value and economic importance. However, at least 40 to 45% of mango fruit is lost during post-harvest handling primarily due to inadequate storage facilities for mango fruit preservation. In this study an improved evaporatively cooled store was developed. The external surfaces of the cooler were sprayed with near infrared reflecting paint (NIR). The mixing ratio of NIR paint and water was 1:2. The dimensions of the cooler were 0.84m x 0.84m x 1.5m. The cooler had a storage space of 0.75m3 and was constructed from locally available materials including hardwood and charcoal. A 12V fan was used to draw air into the cooler. The charcoal was kept moist by water dripping by gravity from horizontally laid pipes on the roof. A computer simulation model for
predicting the performance of the cooler was developed on java platform. The input parameters of the model were inlet air
conditions, water conditions and charcoal cooler characteristics. The output parameters of the model included saturation efficiency, dry
bulb temperature of the inlet air and cooling capacity. The predicted performance parameters of the cooler included saturation efficiency
which ranges from 66.87% to 68.97%, dry bulb temperature of the outlet air which ranges from 24.54oC to 24.67oC and cooling capacity
which ranges from 105726.44kW/h to 136680.9kW/h. The model results showed that saturation efficiency decreases with increase in inlet air velocity while the cooling capacity increases with increase in inlet air velocity.