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

• Published in: Thermal science and engineering progress 2023-10, Vol.45, p.102140, Article 102140
• Main Authors: Koundinya, Sandeep, Jothilingam, J., Seshadri, Satyanarayanan
• Format: Article
• Language: English
• Subjects: Emission factor; Heat Pump; Steam generation; Waste heat recovery
• ISSN: 2451-9049; 2451-9049
• DOI: 10.1016/j.tsep.2023.102140

•A 60 kW SGHP was developed, numerically and experimentally evaluated, and field deployed for heating applications.•Pilot-scale and numerical studies showed an average heating COP of 2.27 with waste condensate water at 60 ℃.•The field study in a canteen utilizing an LT circuit yielded a system COP of 2.2.•The potential of SGHPs for decarbonization is significant, but it varies depending on the emission factor of the country or location where they are installed.•SGHP with steam compression systems or thermo-compressors can work for higher pressure steam applications. 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 %.