Evaluation on environment-friendly refrigerants with similar normal boiling points in ejector refrigeration system
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Abstract
Based on the “hypothetical throat area” theory and the “constant-pressure mixing” theory, a thermodynamic model for ejector was set up by introducing the real properties of refrigerants. Refrigerants which have similar normal boiling points with each other may act as replacement to each other in substitute progress. In this paper, eight environment-friendly refrigerants were divided into 4 pairs for study according to their normal boiling point. In each refrigerant pair, the entrainment ratios of ejector, system COP, pump power et al. of refrigerants were compared and analyzed. Lastly, the performances of the transcritical and subcritical ejector refrigeration cycles with propylene were calculated and compared.
Keywords
Pump Power Specific Enthalpy Primary Flow Normal Boiling Point R142bList of symbols
- A
Area (m2)
- COP
Coefficient of performance
- GWP
Global warming potential
- h
Specific enthalpy (J kg−1)
- k
Ratio of specific heat
- m
Mass flow rate (kg s−1)
- NBP
Normal boiling point
- ODP
Ozone depletion potential
- p
Pressure (Pa)
- Q
Rate of heat transfer (W)
- s
Specific entropy (J kg−1 K−1)
- T
Temperature (K)
- v
Specific volume (m3 kg−1)
- Wp
Work rate of the pump (W)
- w
Velocity (m s−1)
Subscripts
- c
Condenser
- d
Diffuser of ejector
- e
Evaporator
- ef
Entrained flow
- g
Generator
- gf
Primary flow
- m
Mixing chamber of ejector
- s
Isentropic process
- t
Throat
- 1-6
State points
Greek symbols
- η
Efficiency
- ρ
Density (kg m−3)
- φm
Mixing coefficient
- ω
Entrainment ratio
- ϕg
Ejector characteristic area ratio
Notes
Acknowledgments
The present study was supported by the project of National Natural Science Foundation of China (No. 51406228) and was supported by the Fundamental Research Funds for the Central Universities (2012QNA55).
References
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