적도지역 적용을 위한 50kW 해수온도차발전 사이클 상세설계

Abstract

In this study, the optimal working fluid was selected among the six working fluids used in the performance comparison of a 50 kW Ocean Thermal Energy Conversion for application in the equatorial Pacific Islands, and a detailed design of the cycle using the working fluid was conducted. First, the performance of six types of working fluids was compared and analyzed the turbine rotation for local application. Among them, R1234ze(Z) was selected as the final working fluid because it can be operated at 60 Hz with a turbine speed of 3,600 rpm, so no initial investment is required for grid connection, and it does not require high-pressure facilities due to its low drive pressure. To optimize the cycle of the 50kW Ocean Thermal Energy Conversion demonstration plant using R1234ze(Z), the cycle analysis conditions were modified compared to the previous cycle analysis conditions. By analyzing the local data, the average temperature of surface water was modified to 29.5℃, and the minimum approach of evaporator and condenser was improved to 1.5℃. This increased the heat exchange efficiency, reducing the amount of seawater intake required and reducing the power consumption of the pumps, resulting in a higher net power output. In this analysis, aerodynamic, mechanical, and electrical losses were considered, and the turbine's power conversion losses were also taken into account, and a cycle analysis was performed to approximate the performance that will be seen in actual application.