Bin analyses were performed to determine the annual average COP of the TBS-BC (System 4) and the R-404A
multiplex DX system (System 1) in sixteen cities selected from the eight climate zones of the United States (International Code Council 2006).
ASHRAE (2005) provided data for R-32, R-125, R-404A
, R-410A, R-507, propylene, propane, and isobutane.
R-410A and R-404A
are extensively used for heating, ventilation, air conditioning, and refrigeration (HVAC&R) applications.
The refrigerant circuit (Figure 2), whose working fluid is the refrigerant R-404A
, corresponds to a two-stage compression cycle with a liquid subcooling system.
Available in 1/2 to 6HP configurations that are R-404A
compatible, the new condensing units feature HyperCore microchannel coil technology to allow superior heat transfer capabilities and reduced refrigerant charges compared to standard copper-aluminum round tube plate fin (RTPF) coils.
The SLX uses R-404A
as a refrigerant--a chlorine free chemical without depleting effects on the ozone layer.
Existing deep-freeze and blastfreeze systems using HCFC refrigerants like R-404A
, R-22, or R-502, can be converted.
Part 2, published in the December issue, deals with selection of proper thermostatic charges, capacities of several refrigerant blends relative to both R-404A
and R-22, and examines how existing components on the liquid side of a system may be affected by a retrofit to a newer, high-glide blend.
The compressor calorimeter testing was conducted on R-404A
and its alternative refrigerants for a current production model R-404A
scroll compressor with nominal rated capacities of 23.5 kBtu/hr (6.88 kW) at 20[degrees]F (-6.7[degrees]C) saturation suction temperature, 120[degrees]F (48.9[degrees]C) saturation discharge temperature, 65[degrees]F (18.3[degrees]C) suction temperature and 0[degrees]F (0[degrees]C) subcooling.
If <150 direct GWP for a refrigerant is used as the upper limit, one quickly realizes there are only a few candidates that can meet this limit for R-134a, R-404A
, R-410A and R-22 applications.
With this range customers can chose between R-134a and R-404A
refrigerants to suit the ambient temperatures the units will be operating in.
Thermo King's cryogenic refrigeration unit replaces the usual diesel engine, compressor and R-404A
refrigerant with carbon dioxide, an extremely efficient refrigerant.
Standard features include a stainless steel exterior, separate ice and water chutes and a quiet, air-cooled R-404A
Both the VK and VKL compressors can operate at speeds as high as 1,800 RPM and are available for R-717, R-22, R-404a
, as well as other refrigerants.