Low-pressure steam generating heat pump – A design and field implementation case study

Abstract

Steam is commonly used in industries for cooking in their kitchens, and diesel or LPG-fired boilers are often used to generate it. The use of a high-temperature heat pump to generate steam can help reduce emissions and lower the CO2 footprint by eliminating these fired sources. The following study details the design and consistent operation of a steam-generating heat pump (SGHP) system that employs a high-temperature scroll compressor and functions on the principles of a vapour compression system. SGHP generates steam with a stagnation pressure of 1.5 bar, a flow rate of 81.43 kg/hr, and a temperature of 108.52 ℃. The system was simulated using DWSIM under steady-state conditions with no pressure drop, and steam was generated through a flash tank. SGHP was also installed in a canteen that previously used a diesel boiler, and data from 31 days of operation was analyzed to evaluate system performance, environmental impact, and overall savings. The system COP was 2.2. The analysis showed that an average daily energy savings of 57.79 kWh and an average cost savings of Rs. 1125.46 were achieved. SGHP (with high temperature circuit only) increased carbon emissions by 20.3 % compared to diesel, based on India's emission factor of 790 g CO2/kWh. However, considering the emission factor of the European Union, the steam-generating heat pump has the potential to reduce carbon emissions by 57.8 %.