Development of direct seawater-cooled LiBr–H2O absorption chiller and its application in industrial waste heat utilization

In hot coastal regions where fresh water is scarce, absorption chillers driven by industrial waste heat and cooled by seawater are suitable to achieve cooling demands, and it contributes to improving energy efficiency and reducing CO2 emissions. However, seawater cooling strategy is a trade-off between performance and cost for practical applications, and there are few direct seawater-cooled absorption chillers. In addition, the integration of absorption chillers into a waste heat utilization network is often not well planned, and thus the waste heat is usually not used efficiently. This paper presents the direct seawater cooling strategy for the absorption chiller in terms of high performance and low cost by comparing different seawater cooling strategies numerically and experientially. To realize efficient energy utilization, an existing waste heat utilization network is analyzed graphically based on pinch method, and the available heat for absorption chillers is obtained by the position of the pinch point. According to the available heat, the direct seawater-cooled absorption chiller with a designed cooling capacity of 4200 kW is developed by using titanium tubes, anticorrosive paints and rubber covers to construct the corrosion-resistant condenser and absorber. The site testing results show an average cooling capacity of 3043 kW and an average COP of 0.77 of the absorption chiller when the temperatures of the hot water, seawater and chilled water varies from 98.7 °C to 80.7 °C, from 30.2 °C to 34.2 °C, and from 14.4 °C to 8.6 °C, respectively. Due to the integration, the energy and exergy efficiencies of the waste heat utilization network is improved by 55.9% and 86.1%, respectively. The application demonstrates that the direct seawater-cooled absorption chiller holds the promise for waste heat utilization in coastal regions.