Comparison of Different Refrigerants Refrigerant Toxicity Flammability GWP ODP R-744
(carbon dioxide) A 1 1 0 R-717 (ammonia) B 2L 0 0 R-290 (propane) A 3 5 0 R-22 (HCFC) A 1 1760 0.034 R-134a (HFC) A 1 1300 0 R-410A (blend of A 1 1920 0 HFCs R-32/R-125 at 50/50) R-600a (isobutane) A 3 20 0 R-1234yf (HFO) A 2L <1 0 Table 2.
(3) REFRIGERANT GLOBAL WARMING OZONE DEPLETION ASHRAE SAFETY POTENTIAL (GWP) POTENTIAL (ODP) CLASSIFICATION R-22 1,810 0.040 A1 R-404A 3,922 0 A1 R-507A 3,985 0 A1 R-407A 2,107 0 A1 R-410A 2,088 0 A1 R-407F 1,825 0 A1 R-1270 3 0 A3 R-290 (Propane) 3 0 A3 R-744
(Carbon 1 0 A1 Dioxide) R-717 (Ammonia) <1 0 B2L
The second system uses R-744
(C[O.sub.2]) as refrigerant.
These new candidates are often blends of ultra-low GWP refrigerants (R-1234yf and R-1234ze (E)) with traditional HFCs of R-134a, R-125, R-152a, R-32 and even C[O.sub.2] (R-744
) to achieve the desired capacity or non-flammability for each application.
The recovered R-744
is stored under pressure in a vacuum insulated tank under the chassis of the truck or articulated trailer.
Only a few correlations were developed for R-744
two-phase flow: Martin et al.
In that sense, R-744
has been the focus of research for use in many refrigeration applications, such as heat pumps (Mukaiyama 2002), air conditioners (Hafner et al.
Furthermore, a variety of refrigerants were investigated, including R-32, R-134a, R-404A, R-1234yf, R-717, and R-744
The Copeland[TM] Stream series, a range of semi-hermetic compressors designed for medium temperature R-744
transcritical applications, complements the recently launched Stream range for HFC refrigerants.
(9.52 mm) copper tube and louvered fins was found suitable to work with high R-744
pressures and has been studied as a gas cooler in a test rig built for testing carbon dioxide (C[O.sub.2]) equipment operating with air as a secondary fluid.
The 25-year old rink's redesign uses the natural refrigerant R-744
as the primary and secondary working fluid.
The 100% C[O.sub.2]-based refrigeration system for ice rinks that was developed in this project is a unique refrigeration system that uses the natural refrigerant R-744
(carbon dioxide) as primary and secondary working fluid (this system has Canadian patents with U.S.
Key Coolant Properties (ASHRAE Best Practices for Datacom Facility Energy Efficiency) Coolant Freezing Point, Thermal Specific heat, [degrees]F Conductivity, Btu/lb * ([degrees]C) Btu/h * ft * [degrees]F [degrees]F (W/m (J/K * kg) * K) Dielectric, FC-87 -175 (-115) 0.033 (0.057) 0.251 (1050) Water 32 (0) 0.347 (0.6) 1.004 (4203) Ethylene -36 (-38) 0.215 (0.372) 0.788 (3299) glycol/water (50:50 v/v) R-134a -154 (-103) 0.048 (0.083) 0.337 (1410) R-744
-70 (-57) 0.049 (0.085) 0.815 (3412) Coolant Density, Latent Heat of lb/[ft.sup.3] Vaporization, (kg/[m.sup.3]) Btu/lb (kJ/kg) Dielectric, FC-87 103.6 (1659) 44 (102) Water 62.3 (998) 1058 (2460) Ethylene glycol/water (50:50 v/v) 67.8 (1086) R-134a 76.4 (1223) 93 (216) R-744
48.4 (775) 66 (153) Water.
The series offers what the company calls "Best in Class" performance in F-gas applications with CoreSense[TM] diagnostics technology and a C[O.sub.2] transcritical compression range completing the company's R-744
Phillip Johnson, Director of Engineering, McQuay International, Staunton, VA: More than 100 years of industrial refrigeration industry practice agree with this paper's conclusion that carbon dioxide (R-744
) is an excellent refrigerant for low-temperature refrigeration applications with moderate lift.