Novel configuration of dual-temperature condensation and dual-temperature evaporation high-temperature heat pump system: Carbon footprint, energy consumption, and financial assessment

To achieve the goal of carbon neutrality for the application of industrial heating by recovery waste heat, the concept of dual-temperature condensation and dual-temperature evaporation is proposed for the high-temperature heat pump (HTHP) by introducing the techniques of ejector and two-stage compression. The energy, exergy, emission, and economic models are developed and optimized for the two new proposed systems. Then, the energy consumption, CO2 emissions and cost (LCC) during the whole life cycle are compared with five existing heat pumps and four traditional boilers. The highest coefficient of performance (COP) of heat pump (HP) can be got when intermediate water temperature on the heat sink side is optimum. The new proposed systems have better performances than the other five HTHPs. During the rated working condition, discharge temperature decreases by the use of dual-temperature condensation and dual-temperature evaporation HP with an ejector (Ej-DCDE). The optimal COP of Ej-DCDE-2 is 4.25, which is 11.55% and 1.43% higher than dual-temperature condensation and single-temperature evaporation HP and Ej-DCDE-1, respectively. The exergy destruction of Ej-DCDE-2 is reduced by 27.88% compared with basic heat pump (Base). Moreover, Ej-DCDE-2 has the lowest primary energy consumption of 14.62 ktoe, 22.19% and 25.09% lower than Base and oil-fired boiler during the total working period, respectively. In general, HTHPs have lower carbon dioxide, gaseous and particular pollutant emissions compared with boilers, especially Ej-DCDE-2. Finally, Ej-DCDE-2 has the minimum LCC, which is 14.67% and 11.75% less than Base and coal-fired boiler. Ej-DCDE-2 shows the most potential advantages of all the heating solutions and is recommended to replace traditional boilers for industrial heating.