Hybrid Evaporative and Radiative Cooling as a Passive Low-Cost High-Performance Solution for Food Shelf-life Extension

How can we provide low-cost off-grid temperature regulation for post-harvest food preservation under different climate conditions?

Research Strategy:
(*) Passively regulate temperature of past-harvest food with both evaporation and thermal radiation without electricity
(*) Use low-cost and locally available materials in rural areas to design the passive cooling unit that provides high cooling performance under various climate conditions

Food loss and waste account for nearly a third of all food produced in the world, presenting grand societal, economic, and environmental challenges for the 21st century. In developing countries where food security is still a great concern, food loss can largely be attributed to a lack of proper temperature regulation of post-harvest food. Passive cooling storage of post-harvest food without electricity could be particularly attractive to reduce food insecurity and promote economic development. Previous passive cooling solutions such as evaporative cooling or radiative cooling either do not function well under the sun or can only reach low temperatures at locations of very high altitudes and low relative humidity. Here, to enable wider adoption of passive cooling, we propose to build a low-cost high-performance hybrid-cooling food storage unit with its temperature regulated by simultaneous evaporation and thermal radiation. Our new cooling architecture, which will be made from cheap and fully scalable materials, is solar-reflecting, IR-emitting, evaporative, and thermal insulating. Our heat and mass transfer model shows that the hybrid cooling unit significantly outperforms previous passive technologies. It reaches lower stagnation temperatures with much less water consumption compared to conventional evaporative cooling. It drastically increases the cooling power and performs well under a much wider range of climate conditions compared to radiative cooling. In locations with RH < 50%, our storage unit can at least double the food shelf-life. Once developed, we hope to disseminate the technology in rural communities and partner with global institutes, labs and foundations to maximize our reach and impact. Postdoctoral associate Zhengmao Lu and graduate student Arny Leroy will work together on this project.