Comparison between modeling and experiments on a two-stage rotary vane expander for an HFC-410A air conditioning system

Abstract

Substituting throttle valve with expander can effectively enhance the performance of a refrigeration system. A novel rotary vane expander with two-stage internal expansion was developed for HFC-410A air conditioning system. The structural characteristics and operating principle of the expander are presented. A simulation model including thermodynamic and dynamic calculations is established. An HFC-410A air conditioning system was built for the purposes of testing the prototype and verifying the model. Through the experimental results, the maximum volumetric efficiency was 55% at 1800 r/min and the maximum isentropic efficiency of the prototype was 31.5% at 1404 r/min. The maximum improvement in the system coefficient of performance was 10.3% at 1404 r/min, in comparison with the coefficient of performance without the expander. Higher rotational speed could reduce leakage time thus improve volumetric efficiency; however, it also generated more frictional loss that eventually deteriorated the expander performance. Properly increasing the condensation pressure could help reducing frictional loss at high speed, thus further improve the overall performance of the expander. The results also show that the expander has a better adaptability to variable operating conditions at high rotational speed.

A review on expanders and their performance in vapour compression refrigeration systems

“…With a conventional refrigerant (R-410A), the maximum reported expander efficiency is 61% with a rotary vane expander (Xia et al, 2013). The highest COP improvement measurement reported for a CO 2 system was approximately 30% (Kohsokabe et al, 2006;Kakuda et al, 2009) and for a non-CO 2 system (R-410A) was 10.3% (Wang et al, 2013). A summary of various expander experimental data available in the literature is tabulated in Tables 1-3.…”

“…From their simulation, it was found that the expander could improve the system's COP improvement by 6-22%, depending on the condensation temperature and the expander's inlet degree of subcooling. A year later, Wang et al (2013) reported further a further study, comparing modeling data with and experimental. This study found that even with R-410A as the refrigerant, the expander could improve the COP by 10.3% as compared to a…”

Performance analysis of a novel oil-free rotary compressor

“…The inlet is considered to be a Borda-Carnot-type restriction with constant c q discharge or loss coefficient which is a predefined parameter. The mass-flow rate can be estimated by the following equation (4).…”

“…When the position of the valve is given, the mass flow across the valve can be calculated using also equation (4). Valve mass (m v ), the viscous coefficient (k v ), and valve spring stiffness (C) are predefined for the system.…”

“…1,2 Also, combined with a feeding valve, the RP unit can be effectively used as an expansion unit. [3][4][5] The RP compressors are mainly applied in compact refrigerator or air-condition (AC) systems. The RP compressors have gone through significant development since their first use, which resulted with series of sub-variations, and by the end of 2015, Oui and Yap 6 estimated that 90% of household ACs, typically with cooling capacity below 15 kW, are equipped with RP compressor.…”