Technical and economic analysis of hot water generation using wastewater heat pump for an commercial building

In recent years, due to the increasing interest in energy efficiency and alternative energy sources, the use of heat pumps for heating, cooling, and domestic hot water production has gained prominence. Air-source heat pumps are preferred as the first choice for their ease of applicability compared to water-source heat pumps. However, it is possible to popularize wastewater-source heat pumps by utilizing the waste heat in the continuously used domestic hot water in our daily lives. This study examines the use of a heat pump that utilizes the energy from the waste sanitary water of an industrial facility for the production of domestic hot water. The considered heat pump system is compared with alternative fossil-fueled steel boiler systems in terms of energy, economy, and environmental impact. Instead of the commonly used R410A refrigerant in water-source heat pumps, the energy and exergy analyses of a heat pump operating with alternative refrigerants R290, R32, and R407C are also included in the study. Initial investment costs and 15-year operating costs for these systems are taken into account in the comparison. Carbon emissions are becoming increasingly important for sustainability in today's world. Therefore, in addition to energy and economic analyses, environmental impact factors are also evaluated in this study. Carbon emissions of the wastewater-source heat pump (WWHP) based on the refrigerant used are determined, and these values are compared with emissions from fossil-fueled systems. The COP value for the wastewater-source heat pump system with R290 refrigerant is calculated as 3,57, followed by the R32 system with a COP value of 3,53, the R410A system with a COP value of 3,35 and the R407C system with a COP value of 3,28. When comparing the payback periods of the investments, the wastewater-source heat pump system is more advantageous than other traditional systems. Additionally, in terms of carbon emissions, the amount of CO2 emitted by the wastewater-source heat pump system to the environment in 15 years is much lower than the amount emitted by fossil-fueled systems in one year.