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Thermodynamic Analysis and Comparison on Low Temperature CO2-NH3 Cascade Refrigeration Cycle(PDF)

Transactions of Tianjin University[ISSN:1006-4982/CN:12-1248/T]

Issue:
2003年03期
Page:
252-255
Publishing date:

Info

Title:
Thermodynamic Analysis and Comparison on Low Temperature CO2-NH3 Cascade Refrigeration Cycle
Author(s):
ZHA Shi-tong 1 2 MA Yi-tai2 SHEN Jiang1 LI Min-xia2
(1. Refrigeration and Air-Conditioning Engineering Department, Tianjin University of Commerce, Tianjin 300400, China; 2. Thermal Energy Research Institute, School of Mechanical Engineering, Tianjin University, Tianjin 300072,China)
Keywords:
DOI:

Abstract:
This paper is focused on the cascade refrigeration cycle using natural refrigerant CO 2-NH 3. The properties of refrigerants CO 2 and NH 3 are introduced and analyzed.CO 2 has the advantage in low stage of cascade refrigeration cycle due to its good characteristics and properties. The thermodynamic analysis results of the CO 2-NH 3 cascade refrigeration cycle demonstrates that the cycle has an optimum condensation temperature of low stage and also has an optimum flow rate ratio.By comparing with the R13-R22 and NH 3-NH 3 cascade refrigeration cycles, the mass flow rate ratio of CO 2-NH 3 is larger than those of R13-R22 and NH 3-NH 3, the theoretical COP of CO 2-NH 3 cascade refrigeration cycle is larger than that of the R13-R22 cascade cycle and smaller than that of the NH 3-NH 3 cascade cycle. But the real COP of CO 2-NH 3 cascade cycle will be higher than those of R13-R22 and NH 3-NH 3 because the specific volume of CO 2 at low temperature does not change much and its dynamic viscosity is also small.

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Last Update: 2011-05-02