Evaluating the potential of using ethanol/water mixture as a refrigerant in adsorption cooling system by using activated carbon - sodium chloride composite adsorbent

Abstract

Thermal properties and adsorbent - refrigerants compatibility, influence heat and mass transfer dynamics in adsorption cooling systems (ACS). Activated carbon (AC) + NaCl (10–35.7% w/v) composite adsorbents were paired with either high purity (99.7%) or low-grade ethanol (60% ethanol/ 40% water) refrigerants to assess the potential of ethanol/water mixture as a refrigerant. The ACS with activated carbon-sodium chloride (AC + NaCl) composites adsorbent had a coefficient of performance and specific cooling power of up to 0.091 and 79 W kg−1, respectively, when paired with high purity ethanol, which increased to about 0.146 and 150 W kg−1, respectively, when paired with low-grade ethanol. About 16–25 MJ per cycle was needed for evaporation of refrigerants in AC + NaCl composites adsorbent when paired with the low-grade ethanol, whereas more energy, 27 MJ per cycle, was required to evaporate low-grade ethanol when paired with unmodified AC in ACS. The study has shown that the thermal and mass transfer performances of AC + NaCl composites adsorbents superseded that of unmodified AC providing the potential for low-grade ethanol to be used as a potential alternative refrigerant in ACS especially in areas where pure ethanol is limited.