Performance comparison of thermal power generation‐organic Rankine cycle combined cycle system for ships waste heat utilization under different bottom cycle ratios

Abstract

AbstractWaste heat recovery technology has gained popularity due to its ability to save energy for both financial and environmental reasons. In this article, a new technology, thermal power generation (TEG)‐organic Rankine cycle (ORC) combined cycle system, is proposed to recycle cascaded waste heat of ships. The bottom cycle ratios are an important parameter affecting the combined cycle system, but its effect under more working conditions is unknown. Therefore, keeping the evaporator pressure at 0.7 MPa, the environmental‐friendly R245fa working fluid is employed to implement an experimental study on the variation law of the main performance parameters such as the system power output (Wnet), the system thermal efficiency (ηs), power‐production cost (Cg), and waste heat utilization of main engine flue gas (fg) under different TEG/ORC bottom cycle ratios (BCR). At the same time, the TEG‐ORC combined cycle system's performance of the R22 and R245fa is compared. With the increase of the BCR, the Wnet, ηs, and fg increase, but the Cg of the system decreases. When the BCR is 0.885, the Wnet, ηs, Cg, and the rate of fg is 688.4 W, 9.09%, 0.5194 $/kWh, and 85.07%, respectively. This study provides a reference for the clarification and further optimization of the TEG‐ORC combined cycle mechanism.