Comparative thermodynamic assessment of n-Pentane and R123 for industrial waste heat recovery

Introduction: Industrial waste heat recovery using Organic Rankine Cycle (ORC) offers a promising approach to improving power plant efficiency and reducing energy losses. This study investigates the thermodynamic performance of n-Pentane and R123 as working fluids in an organic Rankine cycle for industrial waste heat recovery using process data from a thermal power plant in Ghana. Materials and methods: Given the limited number of controlled comparisons between n-Pentane and R123 for industrial flue gas recovery, an Aspen Plus model was developed and analyzed under steady-state conditions using the Peng–Robinson (PR) equation of state. The effects of key operating parameters, including pump discharge pressure, working fluid mass flow rate, and turbine discharge pressure, were evaluated through a sensitivity analysis. Results: Under the base case operating conditions of 12 bar pump discharge pressure, a 170 °C heat stream temperature, and a turbine discharge pressure of 2 bar, the results showed that n-Pentane achieved a higher net work output of 1943.06 kW, whereas R123 attained a superior thermal efficiency of 15.2% compared with 14.4% for n-Pentane. Sensitivity analysis revealed an optimal pump discharge pressure of approximately 13 bar, beyond which efficiency gains diminished. Conclusions: The results demonstrate that n-Pentane is more suitable for maximum power output, whereas R123 provides superior thermal efficiency under the evaluated operating conditions. These findings highlight fluid-specific performance trade-offs relevant to ORC design and underscore the importance of working fluid selection for maximizing energy conversion and environmental sustainability in sub-Saharan energy systems.