The difference between several commonly used refrigerant models

At present, the commonly used refrigerant models include R410a, R134a, R407C, and R22. The editor will briefly analyze the differences between them.

R134a is a single-component refrigerant, while R407C and R410a are mixed refrigerants. Wherein 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 it can be tailored to synthesize a refrigerant 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 will have a certain impact on the overall operation, reliability, cost and market acceptance of the air conditioning system . What is of great interest to everyone is that the new refrigerant has different heat transfer and pressure drop resulting in different refrigerant transfer performance, which will ultimately have a significant impact on system design and system performance. We briefly discuss the differences in the performance characteristics of these common refrigerants.

The capacity of R134a is smaller than that of R22, and the pressure is lower than that of R22. Because of these characteristics, R134a air conditioners of the same capacity need to be equipped with a compressor with a larger displacement, a larger evaporator, condenser and pipeline. The final result is that to manufacture and operate a system with the same cooling capacity as R22, R134a system will require higher costs.

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

The capacity and pressure of R410a refrigerant are higher than R22, and the operating pressure is 50%-60% higher. The result of high pressure and high gas density is that not only compressors with smaller displacements can be used, but also smaller diameter pipes and valves can be used. The use of a high-pressure exhaust valve eliminates the hidden dangers caused by the high-pressure condensation of the system. The thick compressor casing allows the system to withstand higher operating pressures. Another advantage of making the compressor thicker is that the operating noise of R410a is significantly lower than that of R22 compressor by 2-4 decibels.

Compared with the R22 system, the R410a refrigerant system has a significant heat transfer advantage—the heat transfer of the evaporator is 35% higher, and the condenser is 5% higher. The system heat transfer coefficients of R134a and R407C are lower than R22. Under the same mass flow, the pressure drop of R410a is small, making it possible to use smaller pipes and valves than R22 or other refrigerants. This will reduce more material costs for the manufacture of R410a systems, and it is more likely to be more advantageous in long piping home appliances and multi-line systems. Of course, only by redesigning the system can the R410a's heat transfer and small pressure drop advantages be fully utilized-for example, the following optimization techniques can be considered, using smaller diameter coils, different fin structures and increasing the length of the circulation loop to reduce The number of refrigeration circuits. In the end, we can see that in the system redesigned for R410a refrigerant, the use of smaller-volume evaporator and condenser, the cost is lower, and the refrigerant charge can be reduced by up to 30%. The reduction of the refrigerant charge can not only reduce the cost, but also improve the reliability of the entire system.

In a system with the same cooling capacity and the same condensing temperature, the system energy efficiency ratio (COP) of R410a refrigerant can be 6% higher than that of R22. This is because the compressor has lower losses in the compression process, the evaporator and condenser have stronger heat transfer, and the pressure drop in the entire system is smaller. Efficient heat transfer and smaller pressure drop make it lower condensing temperature and higher evaporating temperature under the same operating conditions, which makes the compressor a better one with less power consumption and higher efficiency ratio. Scope of operation. In addition, for R410a's low compression loss characteristics, large compressors in small commercial air-conditioning systems benefit more than small household air-conditioning compressors.