Comparison of Refrigerant Gas R32 and R410a

Comparison of R32 and R410A

Saturation pressure: 

R32 and R410A have similar pressures. So it is easier to develop R32 system based on R410A platform.

Critical temperature: 

R32 has a higher critical temperature, so the COP is higher.

Latent heat of evaporation: 

The heat required to evaporate R32 is higher than that of R410A, so the mass flow rate per unit cooling capacity is smaller and the COP is higher.

Isentropic efficiency: 

This can affect the system pressure ratio and exhaust temperature. Therefore, the pressure ratio of R32 is slightly higher than that of R410A.

Volumetric cooling capacity:

The volumetric cooling capacity of R32 is much higher than that of R410A, so it can reduce the system pipe size and improve efficiency.

Density: The density of R32 is much smaller than that of R410A, so the charge is smaller, but because the unit of measurement for GWP is kilogram, the overall climate impact of the refrigerant in the system is lower than the recommended value of GWP.

In summary, R410A and R32 have better system performance and require a smaller refrigerant charge. But an important problem is that the exhaust temperature of R32 is higher. The direct consequence is that oil degradation can cause various compressor failures, such as bearing seizure, low system performance, and low compressor performance. Therefore, the exhaust temperature should be limited to an acceptable level to ensure the normal operation of the system and compressor. Generally, the temperature of the exhaust gas can be controlled by the refrigerant. Liquid injection can directly solve the problem of excessive exhaust temperature. As shown in Figure 2, part of the condensed liquid is injected into the scroll compressor through the electronic fuel injection valve to absorb the heat of the intermediate compressed gas, and then vaporizes. Therefore, the exhaust temperature can be effectively reduced. And the mass flow rate of the injected liquid can be easily adjusted through the fuel injection valve.