Energy, exergy, and environmental analysis of clean refrigerant-based heat pump for hotel application in India

Abstract

Hotel heating systems often rely on fossil fuels or high-global warming potential (GWP) refrigerants, leading to high emissions and operational costs. With strict environmental regulations and the push for sustainability, there is growing demand for efficient, low-GWP solutions. This study explores a heat pump using refrigerants with GWP < 150, designed to supply 55 °C hot water for hotel applications. Such applications are perceived to be in high demand in the near future, especially in the Indian context, where the dual challenge of adverse environmental impact and high operating costs is addressed. The heat pump system is designed to fully meet the heating demand of a typical hotel (80 kW) in India, while utilizing its cooling load to partially reduce the existing chiller load. Total equivalent warming impact analysis explored the system's overall carbon footprint. The results show that in subcritical systems, maintaining a 3-K pinch point requires a condensing temperature of about 52–53 °C, whereas R744 offers the most favorable temperature glide. Among the refrigerants analyzed, R152a accomplishes the highest heating coefficient of performance of 4.96, while natural refrigerants such as RE170, R717, R600a, and R290 exhibited a lower but comparable performance. Exergy analysis further corroborates these findings, with R152a reaching a maximum exergy efficiency of 45.33%, followed by RE170 at 45.03%. Natural refrigerants RE170 and R717 exhibited the lowest total equivalent warming impact (TEWI) values, reinforcing their potential as sustainable alternatives for such applications. The study concludes that natural refrigerants offer the best balance between energy efficiency and environmental impact.