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The off-grid location and unreliable electricity supply to medical clinics in remote parts of India make it difficult to safely store vaccines and other medications using traditional refrigeration systems. The Engineers in Technical Humanitarian Opportunities of Service-learning (ETHOS) program at the University of Dayton, in collaboration with Solar Alternative and Associated Programmes (SAAP) of Patna India, are developing a novel refrigeration system which works on the principle of solar thermal adsorption. This refrigeration system does not require electricity for operation and uses safe, environmentally benign and locally available adsorption pair of ethanol-activated carbon. A bench-scale prototype was developed at the University of Dayton using ethanol-activated carbon as working pair which can generate evaporative temperatures between 2oC and 8oC. The existing horizontally oriented system can achieve targeted refrigeration temperatures (2-8oC) during the adsorption cycle and ethanol can be desorbed from the activated carbon during desorption. However, the horizontal geometry inhibited the return of liquid ethanol to the evaporation chamber. A new vertical oriented bench scale system was built to addresses the limitation of the original prototype. The effects of double activated carbon on evaporative cooling, heating temperature and time during desorption, and possible decomposition of ethanol during desorption was analyzed. The evaporator temperature -12.7oC achieved during the experiments indicates better adsorptive cooling with double activation technique of activated carbon. Experimental results suggested better desorption happens at elevated temperature (105 - 115oC) and most of the desorption happens in the first 2 hours of heating the activated carbon chamber. The pressure drops on ethanol side pressure gauge reading during desorption and analysis of mass spectroscopy of desorbed ethanol obtained from the chemist showed possible decomposition of ethanol preventing multiple cycle operation of the system.
Jun-Ki Choi, Amy R Ciric
Primary Advisor's Department
Stander Symposium poster
"Understanding the effects of double activated carbon, desorption temperature and time, and possible ethanol decomposition during desorption on Solar Thermal Adsorption Refrigeration (STAR) system" (2018). Stander Symposium Posters. 1415.