Conceptual design, modelling and optimization of an integrated system by combining Organic Rankine Cycle and absorption refrigeration cycle for efficient energy recovery

Background: Organic Rankine cycle (ORC) has been extensively applied to electricity generation by utilizing low grade residual heat. Methods: A cascaded lithium bromide refrigeration cycle/ ORC to recover waste heat is proposed and investigated in this paper. Several critical parameters in terms of refrigeration temperature, the types of organic working medium, ORC high pressure, turbine discharge pressure, and segment temperature are studied to design and optimize the proposed system. Furthermore, the proposed system is compared with the conventional ORC that utilizes the same heat source in the turbine outlet pressure and net electricity generation (NEG), then the two systems are depicted and compared in a temperature-entropy diagram. The results indicate that the proposed system using R123 corresponds with the best performance when the refrigeration temperature is 2 degrees C. The NEG reaches 53.13 kW, and the maximum exergy efficiency is 37.21%. The NEG of the proposed system is improved by 28.3% compared with the conventional ORC system.Significant finds: This paper provides a new coupling way to improve the power generation by cascade utilizing low-grade waste heat.(c) 2022 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

This paper proposes a new cascade method to improve power generation utilizing low-grade waste heat and optimizes the key parameters of the system. The results show that the proposed system performs best at a refrigeration temperature of 2 degrees Celsius and can increase the net electricity generation by 28.3% compared to the conventional ORC system.