Addressing industrial waste heat supply variability with Organic Rankine Cycle systems incorporating thermal energy storage

Abstract

The conversion of waste heat to power presents a significant opportunity to enhance industries' energy efficiency. However, power generation often varies based on market demand. Such variations may adversely influence any recovery system performance. Organic Rankine Cycle (ORC) coupled with Cryogenic Energy Storage (CES) may be used for power generation using waste heat from such industries. The present paper provides an overview of thermal power fluctuations from waste heat. During the first stage, utilizing a four-stage compression process in the CES-ORC system, the thermal load for the ORC/RORC was evaluated at 1.6 MW at a temperature of 176.85 °C. A multi-objective optimization was carried out to balance the conflicting goals of thermodynamic performance, exergy efficiency, and economic performance. Forty-nine working fluids were examined. Among these, eight fluids (Butane, Heptane, Hexane, Pentane, Neopentane, R-134a, R-245fa, and Toluene) were selected. The initial findings indicate that the ORC-RORC achieves its highest net power output (27 kW and 37 kW) when the turbine input temperature is maintained at 200 °C. Furthermore, the first law efficiency of the system is measured to be 16.06 % and 25 % when utilizing Toluene. Overall, Toluene exhibits the lowest LEC values (0.04431, 0.05043) compared to other fluids.

Keywords

• Waste heat recovery
• Power generation
• Organic Rankine Cycle
• Working fluids
• Thermo-economic analysis
• Thermal Energy Storage