Thermodynamic analysis of a modified booster-assisted ejector heat pump cycle with dual condensers

This paper proposes a modified booster-assisted ejector heat pump (MBEHP) cycle with dual condensers for heat pump dryer applications. Based on a basic booster-assisted ejector heat pump (BEHP) cycle, a low-temperature condenser is introduced between the conventional condenser (i.e. high-temperature condenser) and the evaporator to realize the dual-pressure condensation that can provide heat duty at two different temperatures for heating up dryer air. In this case, improvement on cycle performance could be achieved through the use of such dual condensers in the MBEHP cycle. The benefits from the MBEHP cycle are evaluated by using the first and second laws of thermodynamics, and performance comparisons with the BEHP cycle are also presented. The results show that when R134a is used as the refrigerant, the heating coefficient of performance COPhw and COPh of MBEHP cycle under the typical operating condition increase by 50.34 % and 16.97 % compared with those of BEHP cycle, respectively. The performance of MBEHP cycle is superior to that of BEHP cycle under all given operating conditions, especially under severe operating conditions such as high condensing temperature and low evaporating temperature. In typical operating condition, the total exergy destruction of MBEHP cycle is 12.70 % lower than that of BEHP cycle, but the ejector has the maximum optimization potential. Moreover, the heating capacity Qc and the COPhw of MBEHP cycle are 42.49 % and 12.79 % higher using R1234ze(Z) than using R134a, hence R1234ze(Z) is the most suitable refrigerant to replace R134a in the MBEHP cycle among R1234yf, R1234ze(E) and R1234ze(Z).

Automated summary

This paper presents a modified booster-assisted ejector heat pump cycle with dual condensers for heat pump dryer applications. The cycle achieves dual-pressure condensation and improves cycle performance by providing heat duty at two different temperatures. The benefits of the modified cycle are evaluated using thermodynamics and compared with the original cycle. Results show significant improvements in heating coefficient of performance and total exergy destruction with the modified cycle. Additionally, the use of R1234ze(Z) as a refrigerant further enhances the performance of the cycle.