Experimental investigation and industrial application of a cascade air-source high temperature heat pump

For industrial thermal scenarios where there is no waste heat to recycle, the Air-source High Temperature Heat Pump (ASHTHP) is the only choice to replace the traditional industrial boiler and decrease energy consumption. A cascade ASHTHP has been designed and developed to support 125 degrees C hot water, which utilizes R410A and R245fa as working mediums. It is not only theoretically simulated and experimentally investigated, but also applied in an electroplating factory in Ningbo, China to provide 120 degrees C hot water. When the ambient temperature is 20 degrees C and the output temperature is 125 degrees C, the experimental heating capacity of the unit is 121.5 kW with a COP of 1.71. During the experimental investigation, the heating capacity attenuation remains within 19.25 %. Through the comparison and verification of the experimental data, the system simulation results have high accuracy with the error controlled within 5 %. When used in the electroplating factory to provide hot water at 120 degrees C, the cascade ASHTHP units can provide a heating capacity of 480 kW with a COP of 1.8 at the ambient temperature of around 25 degrees C, which results in annual savings of approximately $123,200 and a payback period of 1.65 years.