COMPREHENSIVE ANALYSIS OF ORC-VCC SYSTEM FOR AIR CONDITIONING FROM LOW-TEMPERATURE WASTE HEAT

Abstract

Due to the need to reduce electricity consumption, methods of increasing the efficiency of energy use are being sought. One of the possibilities is the use of low-temperature waste heat for the production of electricity or cooling. Systems that convert heat into cold seem particularly attractive. This approach allows, above all, the removal of the generator. It eliminates the electrical part of the expander and, as a consequence, increases the efficiency of waste heat utilization, simplifies the construction of the ORC turbogenerator, and removes certain restrictions. The paper presents an analysis of the ORC-VCC cycle using waste heat at a temperature of 95℃ and heat up to 130kW. Various novel working fluids (e.g. R1224yd(Z), R1233zd(E), R1336mzz(Z)) are considered. Selected fluids are characterized by low global warming potentials. An in-house code was developed and used to calculate cycle parameters. Single and multi-objective optimization was performed, aiming at the maximization of the ORC efficiency, Net Present Value (NPV) and the Internal Rate of Return (IRR). Pareto frontiers were obtained, and a decision-making method was used to select an optimum solution. The obtained ORC efficiency was 5.25%, COPVCC 0.47 and the cycle efficiency was above 27.1%.