Sibanda Sipho, Workneh Tilahun Seyoum
Agricultural Research Council, Institute for Agricultural Engineering, Pretoria, South Africa.
University of KwaZulu Natal, School of Engineering, Pietermaritzburg, South Africa.
Heliyon. 2020 Jan 28;6(1):e03286. doi: 10.1016/j.heliyon.2020.e03286. eCollection 2020 Jan.
This study developed an indirect air-cooling combined with evaporative cooling (IAC + EC) system for temporary storage of fruit and vegetables (FV) to improve the shelf life of fresh produce under hot and humid climatic conditions. The aim of the study was to investigate the effect of IAC + EC in providing optimum storage environment of temperature and relative humidity (RH) for the tomato fruit compared to storage under ambient conditions. The IAC + EC system had a 53-m storage chamber able to store 3.8 tons of tomatoes. Solar energy during the day and a battery bank facility at night powered the cooling system. The structure was constructed and assembled at Ukulinga research center in Pietermaritzburg. The performance of the IAC + EC was evaluated based on the temperature and the RH measured hourly from 05h00-22h00 daily during a period of 28 days. Temperature and RH were measured in the psychometric unit, various positions in the storage chamber and at ambient conditions. There were significant variations (P < 0.001) in temperature and RH between storage and ambient conditions. The temperature inside the storage chamber was on average 7°C-16°C lower while the average RH was 13%-41% higher than ambient conditions. Temperature and RH at the exhaust end of the IAC + EC storage chamber were 16.40 °C and 88.9% compared to 30.9°C and 47.6% under ambient conditions. Such conditions can enhance the shelf life of FV of moderate respiration rates. Inside the storage chamber, temperature was 15.7°C-16.4°C while the RH was 89.6%-93.8% depending on location. The cooler efficiency varied from 88.04% to 95.6%. The IAC + EC system performed at the same level as evaporative cooling under dry and arid conditions. The results in this study are evidence that IAC + EC system can provide optimum storage conditions for FV as well as being a low-cost technology utilizable in hot and sub-humid to humid areas in sub-Saharan Africa.
本研究开发了一种间接空气冷却与蒸发冷却相结合（IAC + EC）的系统，用于水果和蔬菜（FV）的临时储存，以延长新鲜农产品在炎热潮湿气候条件下的保质期。该研究的目的是调查与在环境条件下储存相比，IAC + EC在为番茄果实提供温度和相对湿度（RH）的最佳储存环境方面的效果。IAC + EC系统有一个53米长的储存室，能够储存3.8吨番茄。白天的太阳能和夜间的电池组设施为冷却系统提供动力。该结构在彼得马里茨堡的乌库林加研究中心建造和组装。在28天的时间里，基于每天05:00 - 22:00每小时测量的温度和RH对IAC + EC的性能进行评估。在湿度测量单元、储存室内的不同位置以及环境条件下测量温度和RH。储存条件和环境条件之间的温度和RH存在显著差异（P < 0.001）。储存室内的温度平均比环境条件低7°C - 16°C，而平均RH比环境条件高13% - 41%。IAC + EC储存室排气端的温度和RH分别为16.40°C和88.9%，而环境条件下为30.9°C和47.6%。这样的条件可以延长呼吸速率适中的FV的保质期。在储存室内，温度为15.7°C - 16.4°C，而RH根据位置在89.6% - 93.8%之间。冷却器效率在88.04%至95.6%之间变化。IAC + EC系统在干燥和干旱条件下的性能与蒸发冷却相同。本研究结果证明，IAC + EC系统可以为FV提供最佳储存条件，并且是一种可在撒哈拉以南非洲炎热、半湿润至湿润地区使用的低成本技术。
