Introduction To Refrigerant R407C - Acson A4LC 10 B Manual

1. INTRODUCTION TO REFRIGERANT R407C

ENVIRONMENTAL FRIENDLY
The Montreal Protocol regulation calls for the phase-out of HCFCs by the year 2030 to prevent the ozone
layer from further depletion. R407C is an environment friendly refrigerant to replace R22. The operating
characteristics of R407C system bears close similarity to that of R22. R407C thermophysical properties
such as pressure-temperature behavior, and heat-transfer characteristic are somewhat similar to the
properties of R22.
Physical Property
Molecular Wt (g/mol)
Vapor Density (kg/m
Liquid Density (kg/m
Boiling Point (°C)
Latent Heat Vap (kJ/kg)
Ozone Depletion Potential
Global Warming Potential
R407C CHARACTERISTICS
R407C is a ternary mixture of R32, R125, and R134a with weight composition of 23%, 25% and 52%
respectively. These three components have different vapor pressure and boiling points. R407C liquid and
vapor components have different compositions when the fluid evaporates or condenses. This gives rise
to a temperature glide where the bubble point and dew point are of different temperatures. The effect of
glide in heat exchangers is that as the refrigerant mixture flows through the tubing at constant pressure,
the evaporating temperature will change as the composition of the liquid and vapor phases change.
Typically, the glide for R407C is about 5°C to 10°C. The extend of temperature glide actually varies with
the pressure and composition of components present in the mixture during the leak.
The main concerns for R407C is its zeotropic nature. When leak occurs and only vapor leaks out, the
composition of the refrigerant mixture left in the system will change. Especially, when the system is idle,
R32 being the lightest component will leak out more than the other components. What remains in the
system will be of different composition. If the leaked system is subsequently top-up with R407C, the
mixture in the system will varies from the original composition percentage ratio.
This composition shift will slightly affect the system performance. However, study has shown that after a
series of repeated leaks and top-ups, the system capacity drops up to 6%.
Another concern for R407C system is the lubricant used for its compressor. Like all HFC refrigerants,
R407C uses polyol ester oil (POE) as its lubricant. This hydroscopic oil is prone to moisture
contamination. Extra precaution must be taken not to expose the R407C system too long to moist air; as
the oil will soak up the moisture into the system.
3
)
3
)
-37.1 to -44.3
1
R407C R22
86.2 86.5
42.0 44.2
1134 1195
-40.8
245 234
0.00 0.05
1600 1700