THE ROLE OF THE
THE ROLE OF THE
THE ROLE OF THE
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HVAC System Overview and Refrigerant Design 143<br />
table 9.8<br />
Performance comparison of co 2 and r-134a at various states<br />
state/variables r134a co 2 (r-744)<br />
state 1<br />
Pressure (bar) 2.28 29.09<br />
Temperature (°C) −6.7 −6.7<br />
Enthalpy (kJ/kg) 246.76 738.79<br />
Latent heat (kJ/kg) 204.8 249.95<br />
Entropy (kJ/kg K) 0.934078 3.99821<br />
Volume (m 3 /kg) 0.088029 0.0126485<br />
state 2<br />
Pressure (bar) 12.81 130<br />
Temperature (°C) 54.4 104.4<br />
Enthalpy (kJ/kg) 282.35 796.86<br />
Entropy (kJ/kg K) 0.934078 3.99821<br />
Volume (m 3 /kg) 0.01649 0.0041827<br />
state 3<br />
Pressure (bar) 12.81 130<br />
Temperature (°C) 48.9 26.7<br />
Enthalpy (kJ/kg) 121.581 559.2<br />
Entropy (kJ/kg K) 0.24211 3.230048<br />
Volume (m 3 /kg) 0.0009032 0.0012006<br />
state 4<br />
Pressure (bar) 2.28 29.09<br />
Temperature (°C) −6.7 −6.7<br />
Enthalpy (kJ/kg) 121.581 559.2<br />
Entropy (kJ/kg K) 0.2593667 3.288624<br />
Volume (m 3 /kg) 0.000034533 0.0042816<br />
Refrigeration effect (h1 – h4) (kJ/kg) 125.18 179.59<br />
Cooling capacity (kW) 5.275 5.275<br />
Ref. flow rate (kg/h) 151.58 107.2<br />
Compressor work (kW) 1.5 1.824<br />
Compressor capacity/volume ref. flow (kW/m 3 ) 2318.33 19761.2<br />
Compressor disp. of CO 2 with respect to R134a 1 8.52<br />
Energy efficiency ratio (Btu/h W) 12 9.87<br />
Condenser/cooler specific heat rejection (kJ/kg) 160.77 179.59<br />
Condenser/cooler heat rejection (kW) 6.8 7.1<br />
Coefficient of performance (COP) 3.52 3.09<br />
Source: Goodbane, M. SAE Paper 1999-01-084, 1999. With permission.