Evaporative Cooling Driven by a Venturi Tube Revisited; Assessing the Performance of Different Refrigerant-Circulating Pairs

This study presents the design, construction, and evaluation of a Venturi Evaporative Cooling System (VECS). The system utilizes a venturi tube to create vacuum conditions that lower the boiling point of refrigerants and promote evaporation. The efficiency of different circulating-refrigerating pairs of liquids is explored and a simple refrigerating cycle is proposed. The performance of the system was assessed by measuring temperature changes within a closed environment, examining the impact of vacuum conditions produced by two circulating fluids (water and ethylene glycol) on the boiling point of three different working substances or refrigerants (ethanol, acetone, and diethyl ether), and determining the coefficient of performance (COP) to gauge the efficiency of the cooling system. The best vacuum achieved was 44.58 kPa using ethylene glycol as the circulating liquid. The lowest temperatures reached were -31°C in the liquid phase using diethyl ether as the refrigerant and -18°C in the enclosed atmosphere. The highest COP attained was 0.00202 for diethyl ether, in comparison with a COP of 1.98 x 10-5 for ethanol (the lowest performance). Further investigation is required to explore the use of different low viscosity circulating-refrigerating immiscible fluid pairs to attain lower pressures and higher evaporation rates, free of non-condensing gases closed environments to further increase the evaporation rate of the refrigerant, use of expansion valves or pumps to complete the cycle to avoid working in batches, and more efficient components in order to achieve better performance of the proposed cycle.