Design for Combined Cycles of ORC with Desalination using Ship Waste Heat Analysis of OTEC control characteristics using PID flow control

Abstract

In this paper, as part of the controls designed for automation systems of the demonstration plant for OTEC(Ocean Thermal Energy Conversion) system, it was carried out dynamic simulation for system stabilization through a working fluid pumpcontrol according to the external conditions change. The seawater temperature condition of Kiribati was applied and the detailed design data of 1MW demonstration plant was applied. Kiribati, which is an annual high temperature surface water condition, reaches a maximum of 31℃during the day and a maximum temperature change of 2℃ occurs daily. Deep water, on the other hand, is below 5.5℃ per year, maintaining a maximum temperature difference of 25.5℃. In addition, 1MW OTEC system applied to Kiribati was applied with 1,864kg/s surface water, 1,503kg/s deep water, 117.7kg/s working fluid flow rate, and maximum evaporation pressure of 1660kPa. The working fluid pump applying PID(Proportional Integral Differential) control is designed by using design data of Xylem's R32 refrigerant high pressure pump and applying variation of head and efficiency according to variation of flow rate of performance curve. In addition, design data of 1MW high pressure turbine developed in 2016 was applied to compare the variation of the head and efficiency with the flow rate change. The heat transfer coefficient and total heat transfer area of the asymmetric plate heat exchanger manufactured in 2018