Title: First and second law analyses of wastewater cooled condenser for a refrigeration system
Authors: Ibrahim Karacayli; Lutfiye Altay; Arif Hepbasli
Addresses: Air Conditioning and Refrigeration Technology Program, Ege High Vocational School, Ege University, 35100, Bornova, Izmir, Turkey ' Department of Mechanical Engineering, Faculty of Engineering, Ege University, 35100, Bornova, Izmir, Turkey ' Department of Energy Systems Engineering, Faculty of Engineering, Yaşar University, 35100, Bornova, Izmir, Turkey
Abstract: In this study, a vapour compression refrigeration (VCR) system with a wastewater (WW) cooled condenser at a temperature range of 27-29°C was designed. The cooling capacity of the system using R134a as the refrigerant was 1.09 kW. The condenser consisted of a coaxial heat exchanger with a capacity of 1 kW. This paper dealt with energy and exergy analyses of the VCR system using WW, as a heat sink. Experiments were performed in order to evaluate the energetic and exergetic performances of the wastewater-cooled condenser (WWC) and the overall system. The convective heat transfer coefficient of WW and refrigerant in the condenser, overall heat transfer coefficient of the WWC, total amount of heat removed by WW, amount of cooling effect, coefficient of performance (COP), exergy destruction rate, and second law efficiencies of the WWC and VCR system were calculated under different WW temperatures and flowrates. Increasing volumetric flowrate of WW from 200 L/h to 400 L/h caused 4.4% improvement in COP, 12.0% reduction in exergy destruction, and 10.3% increase in exergy efficiency.
Keywords: wastewater; refrigeration; energy; exergy; coefficient of performance; COP; second law efficiency.
International Journal of Exergy, 2019 Vol.29 No.2/3/4, pp.155 - 171
Received: 26 Oct 2018
Accepted: 09 Jan 2019
Published online: 27 Jun 2019 *