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 ref...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.展开更多
A vapor liquid equilibrium model and its related interactive energy parameters based on UNIQUAC model for the H2O-NH3-CO2 system without solid phase at the conditions of temperature from 30℃ to 90℃, pressure from 0....A vapor liquid equilibrium model and its related interactive energy parameters based on UNIQUAC model for the H2O-NH3-CO2 system without solid phase at the conditions of temperature from 30℃ to 90℃, pressure from 0.1 MPa to 0.4 MPa, and the maximum NH3 mass fraction up to 0.4 are provided. This model agrees with experimental data well (average relative error < 1%) and is useful for analysis of industrial urea production.展开更多
文摘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.
文摘A vapor liquid equilibrium model and its related interactive energy parameters based on UNIQUAC model for the H2O-NH3-CO2 system without solid phase at the conditions of temperature from 30℃ to 90℃, pressure from 0.1 MPa to 0.4 MPa, and the maximum NH3 mass fraction up to 0.4 are provided. This model agrees with experimental data well (average relative error < 1%) and is useful for analysis of industrial urea production.
