Analysis of an ejector-assisted flash tank vapor injection heat pump cycle with dual evaporators for dryer application

Abstract

In this paper, an ejector-assisted flash tank vapor injection heat pump cycle with dual evaporators (EFVIC) for heat pump dryer applications is proposed based on a basic flash tank vapor injection heat pump cycle (FVIC). An ejector is introduced to recover the expansion work of the system, and a high temperature evaporator is added to utilize the ejector's entrainment ability to reduce the irreversible loss caused by lower temperature difference. The performance improvements of EFVIC are evaluated through energy analysis, exergy analysis and comparisons with FVIC. The results indicate that the volumetric heating capacity and heating coefficient of performance of EFVIC with R1234yf are improved by 66.99 % and 18.88 % compared with those of FVIC using R1234yf, respectively. In addition, the presented cycle achieves better exergy efficiency because the exergy destruction proportion of expansion valves in EFVIC is 75.98 % lower than that in FVIC. Furthermore, the compressor has the highest exergy destruction among all components for EFVIC, accounting for 33.22 % of the total exergy destruction, hence it has the greatest optimization potential. The advantages of the presented cycle performance reveal its energy saving characteristics and application potential in heat pump dryer.