Parametric Analysis of a Power and Water Combined System Based on a Top Organic Rankine Cycle

Abstract

Electricity and freshwater are fundamental demands both for life consumption and industrial production. In this paper, a power and water combined system is proposed, with a humidification dehumidification (HDH) desalination unit coupled to a top organic Rankine cycle (ORC), and the condensing heat from the turbine exhaust is absorbed by the seawater to drive the desalination system. Based on the mathematical models of the combined system, energy and exergy analysis is achieved. After the detailed calculation for the heat and mass transfer characteristics, the system cost is also illustrated to present the economy of the system. The results show that peak values for the output power, 9.51 kW, and freshwater production, 262.97 kg h−1, can be obtained when an evaporation temperature of R245fa, 38.15 K and balance condition of the dehumidifier, arrive simultaneously. The corresponding values of gained output ratio (GOR), 1.66, and efficiency, 1.59, with a minimum specific exergy, 25.46 kJkg−1, indicate the best energy utilization within the combined system. It can be concluded that the characteristics of the dehumidifier are more important because of the value elevation for GOR to 2.5, and declination of specific cost for heat and mass transfer area to 49.24 ¥t−1h, while the effectiveness of the dehumidifier is raised from .85 to .9.