Reducing the power consumption of cascade refrigeration cycle by a new integrated system using solar energy

Abstract

In this paper, to prevent the waste energy and reduce the power consumption in cascade refrigeration cycle (CRC), a new integrated system, including CRC, solar cycle (SC) and organic Rankine cycle (ORC), is proposed. The waste energy in CRC is used to preheat the SC working fluid, thus, the total investment cost is reduced 20% (1099000 $) in comparison with the situation that the CRC’s generated heat is wasted. To investigate the proposed system, the energy, exergy, exergoeconomic and exergoenvironmental analyses were carried out. Considering 500 W/m2 solar radiation for 12 h in a day, it resulted that the coefficient of performance, the energy and exergy efficiencies, and exergoenvironmental impact improvement were obtained as 4.233, 84.53%, 37.05% and 0.6256, respectively. The main exergy destruction was related to solar collectors with 53.10% of total exergy destruction. The unit exergy cost of producing electricity, heating and cooling were calculated as 0.810 $/kWh, 1.395 $/kWh and 0.225 $/kWh, respectively. Meanwhile, the consumed power in the proposed system was reduced by 82.57% in comparison with conventional CRC. Finally, it should be noted that the proposed system could produce 132.72 m3/day hot water at 65 °C, and 2400 kWh/day cooling by consuming 567.01 kWh/day power.