Currently, common refrigerant models include R410a, R134a, R407C, and R22.  

R134a is a single component refrigerant, while R407C and R410a are mixed refrigerants.  Where R410a is a mixture of R32 and R125, and R407C is a mixture of R32, R125 and R134a.  The advantage of mixed refrigerant is that a refrigerant can be synthesized according to the specific requirements of use, taking into account various properties such as flammability, capacity, exhaust temperature and efficiency.  

There are many factors to consider when choosing a refrigerant, because choosing any refrigerant can affect the overall operation, reliability, cost, and market acceptance of an air conditioning system.  Of great interest is the difference in refrigerant transport performance due to differences in heat transfer and pressure drop, which can ultimately have a significant impact on system design and system performance.  We briefly discuss the differences in performance characteristics between these common refrigerants.  

R134a has a smaller capacity and lower pressure than R22.  Because of these characteristics, an R134a air conditioner of the same capacity requires a larger displacement compressor, larger evaporator, condenser and piping.  As a result, the R134a system is more expensive to manufacture and run with the same cooling capacity as the R22.  

The capacity and pressure of R407C refrigerant are close to THAT of R22.  Therefore, the original R22 system can also be applied to R407C system by simply adjusting the system design.  However, the energy efficiency of the system will be reduced by about 5%.  This is due to the fact that R407C has a temperature drift of up to 6 degrees relative to other refrigerants.  Therefore, R407C system will reduce heat transfer and affect the energy efficiency ratio of the system when the standard condenser and evaporator are the same.  

The refrigerant capacity and pressure of R410a are higher than that of R22, and the operating pressure is 50%-60% higher.  The high pressure and high gas density result in smaller displacement compressors as well as smaller pipe and valve diameters.  The use of high pressure exhaust valve eliminates the hidden danger caused by high condensing pressure.  The thick compressor housing exposes the system to higher operating pressures.  Another benefit of making the compressor thicker is that the R410a's operating noise is significantly 2-4 decibels lower than the R22 compressor.  

The R410a refrigerant system has a significant heat transfer advantage over the R22 system -- 35% more heat transfer in the evaporator and 5% more heat transfer in the condenser.  The system heat transfer coefficients of R134a and R407C are lower than that of R22.  With the same mass flow rate, R410a has a smaller pressure drop, enabling it to use smaller pipes and valves than R22 or other refrigerants.  This will make it more possible to manufacture R410a systems at a lower material cost and will be more advantageous in long piping home machines and multicolor systems.  Of course, the advantages of the R410a's small heat transfer and pressure drop can only be fully realized if the system is redesigned -- for example, the following optimization techniques can be considered, using smaller diameter coils, different finned structures and increasing loop length to reduce the number of cooling loops.  Finally, we can see that the redesigned system for R410a refrigerant uses a smaller volume of evaporator and condenser, lower cost, and up to 30% reduction in refrigerant charging.  In addition to reducing the cost of refrigerant charge, the overall reliability of the system can be improved.  

In a system with the same cooling capacity and condensing temperature, the COP of R410a can be 6% higher than that of R22.  This is due to lower losses in the compression process of the compressor, greater heat transfer in the evaporator and condenser, and a smaller pressure drop throughout the system.  Efficient heat transfer and smaller pressure drop allow for lower condensing temperatures and higher evaporation temperatures under the same operating conditions, which gives the compressor a better operating range with less power consumption and a higher efficiency ratio.  In addition, for the low compression loss characteristics of the R410a, large compressors in small commercial air conditioning systems benefit more than small domestic air conditioning compressors.