This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Thermodynamic and Cycle Models for a Low-Pressure CO2 Refrigeration Cycle
Technical Paper
1999-01-0869
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Carbon dioxide (CO2)-based refrigeration systems have been proposed as environmentally benign alternatives to current automotive air conditioners. The CO2 vapor-compression system requires very high operating pressures and complicated control strategies. Recent experimental results indicate that operating pressures comparable to those of current automotive air conditioners can be attained by the inclusion of a secondary carrier fluid (a “co-fluid”), with solution and desolution of the CO2 from the co-fluid substituting for condensation and vaporization of pure CO2.
In this work, modeling tools have been developed to optimize the CO2/co-fluid cycle, including the selection of a co-fluid, the CO2/co-fluid ratio (the “loading”), and the operating conditions. The modeling tools are based on thermodynamic functions (e.g. enthalpy and entropy), which are shown to depend on the heat capacities, densities, and isothermal compressibilities of pure CO2 and of the co-fluid, as well as on the heat of solution of the two. The methodology is demonstrated for a CO2/N-methyl-2 pyrrolidone (NMP) mixture.
An ideal refrigeration cycle model was constructed for the CO2/co-fluid system, using the thermodynamic functions as inputs. The optimal cycles and coefficients of performance (COP) were evaluated for the CO2/NMP mixture under three different environmental operating conditions. The results demonstrate the theoretical feasibility of a CO2/co-fluid refrigeration system with a calculated efficiency intermediate between those calculated for R-134a and transcritical CO2 (assuming ideal hardware for all three).
Recommended Content
Authors
Citation
Greenfield, M., Mozurkewich, G., Schneider, W., Bramos, G. et al., "Thermodynamic and Cycle Models for a Low-Pressure CO2 Refrigeration Cycle," SAE Technical Paper 1999-01-0869, 1999, https://doi.org/10.4271/1999-01-0869.Also In
References
- United Nations Framework Convention on Climate Change Report of the Conference of the Parties on its Third Session held at Kyoto from 1 to 11 December 1997 1998 1997
- Sand J. R. Fischer S. K. Baxter V. D. “Energy and Global Warming Impacts of HFC Refrigerants and Emerging Technologies” Alternative Fluorocarbons Environmental Acceptability Study 1997
- Lorentzen G. Pettersen J. “A new, efficient and environmentally benign system for car air-conditioning” Int. J. Refrig. 16 4 1993
- Spauschus H.O. Henderson D.R. Seeton C.J. Wright D.C. Zietlow D.C. Bramos G.D. Abate W. “Reduced Pressure Carbon Dioxide Cycle for Vehicle Climate Control” SAE paper 1999-01-0868 1999
- Vobach A. R. “Chemically Assisted Mechanical Refrigeration Process” Nov. 24 1987
- Cheron J. “Mise au Point d‧une Pompe a Chaleur a Absorption Resorption: Etude de Couples Solute- Solvant” Comm. Eur. Communities 1984
- Groll E. A. “Modeling of Absorption/Compression Cycles using Working Pair Carbon Dioxide/Acetone” ASHRAE Trans. 103 1 1997
- Rivas O. R. Prausnitz J. M. “Sweetening of Sour Natural Gases by Mixed-Solvent Absorption: Solubilities of Ethane, Carbon Dioxide, and Hydrogen Sulfide in Mixtures of Physical and Chemical Solvents” AIChE J. 25 975 1979
- Henderson D.R. Seeton C.J. “Properties of Working Fluids for Reduced Pressure Carbon Dioxide Systems” SAE paper 1999-01-1189 1999
- Prausnitz J.M. Lichtenthaler R. Azevedo E.G. Molecular Thermodynamics of Fluid Phase Equilibria Englewood Cliffs, NJ Prentice-Hall 1986
- Pitzer K. S. Sterner S. M. “Equations of State Valid Continuously from Zero to Extreme Pressures with H 2 O and CO 2 as Examples” Int. J. Thermophys. 16 511 1995
- Lyckman E. W. Eckert C. A. Prausnitz J. M. “Generalized Reference Fugacities for Phase Equilibrium Thermodynamics” Chem. Eng. Sci. 20 685 1965
- Murrieta-Guevara F. Romero-Martinez A. Trejo A. “Solubilities of Carbon Dioxide and Hydrogen Sulfide in Propylene Carbonate, N -methylpyrrolidone and Sulfolane” Fluid Phase Equil. 44 105 1988
- Zubchenko Y.P. Shakhova S.F. Ladygina O.P. “Solubility of Carbon Dioxide in N-methylpyrrolidone under pressure” Khim. Prom-st. 9 535 1985
- Reid R.C. Prausnitz J.M. Poling B.E. The Properties of Gases and Liquids New York McGraw-Hill 4th 1987
- Holman J. P. Heat Transfer New York McGraw-Hill 4th 1976 403 404