Energy usage of forced air precooling of pomegranate fruit inside ventilated cartons

Energy usage is a crucial factor when computing the cost of storing produce. With the ever-increasing cost of energy and attention to environmental problems, understanding energy use and exploring energy saving options is becoming a priority for the economic sector. In this study, the effect of container design, plastic liners and stack orientation on the airflow, cooling rate and energy usage of forced air cooling of pomegranate fruit were investigated. Electricity usage was calculated based on the power ratings of the air driving fan, evaporator fan, compressor cooling fan and the condenser of the cooling unit with duration of power usage dictated by the seven-eighth cooling time (SECT). SECT for different package types were obtained from the cooling experiments. Efficiency of electricity usage was measured as the ratio of produce cooling accomplished to the total electricity consumed. The energy usage differed by 1.5-fold between container design 1 (CT1) and container design 2 (CT2). Depending on the container design, stack orientation (with respect to the direction of the cooling airflow) can influence the energy usage. Plastic liners affected the precooling process the most, increasing energy usage by up to 3-fold compared to stacks with no liners. Container design with high vent-area reduced the resistance to airflow (RTA) and increased fruit cooling rate (reduced SECT), and this may offer the most economically feasible way to reduce electricity use during precooling.