Differences between different types of refrigerants

At present, the commonly used refrigerant models are R410a, R134a, R407C and R22. The differences between them are briefly analyzed under the Ura Chemical Small Edition.

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

There are many factors to consider when choosing refrigerant, because choosing any kind of refrigerant will affect the overall operation, reliability, cost and market acceptance of air conditioning system. It is very interesting to note that the new refrigerants have different refrigerant transport performance due to their different heat transfer and pressure drop, which will ultimately have a significant impact on the system design and performance. We briefly discuss the differences in performance characteristics between these common refrigerants.

The capacity of R134a is smaller than that of R22, and the pressure of R134a is lower than that of R22. Because of these characteristics, R134a air conditioners with the same capacity need to be equipped with a larger exhaust compressor, a larger evaporator, condenser and pipeline. Ultimately, the R 134a system will require higher costs to manufacture and operate a system with the same cooling capacity as R 222.

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 ratio of the system will be reduced by about 5% compared with the original system. This is because 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 in the same standard condenser and evaporator.

The capacity and pressure of R410a refrigerant are higher than that of R22, and the operating pressure is 50% - 60% higher. As a result of high pressure and high gas density, not only compressors with smaller exhaust volumes, but also pipelines and valves with smaller diameters can be used. The use of high-pressure exhaust valve eliminates the hidden danger of condensing high pressure in the system. Thick compressor housing enables the system to withstand higher operating pressure.  Compressors are made thicker and heavier. The noise of R410a compressor is 2-4 decibels lower than that of R22 compressor.

Compared with R22 system, R410a refrigerant system has a remarkable advantage of heat transfer - 35% higher heat transfer in evaporator and 5% higher heat transfer in condenser. The heat transfer coefficients of R134a and R407C are lower than those of R22. At the same mass flow rate, the pressure drop of R410a is smaller, making it possible to use smaller pipes and valves than R22 or other refrigerants. This will make it more possible to reduce the cost of materials for manufacturing R410a systems and have more advantages in long piping household computers and multi-online systems. Of course, only by redesigning the system can R410a's advantages of heat transfer and low pressure drop be brought into full play - for example, the following optimization techniques can be considered, such as using smaller diameter coils, different fin structures and increasing the length of circulation loop, and reducing the number of refrigeration circuits. Finally, we can see that in the redesigned R410a refrigerant system, the use of smaller evaporators and condensers is cheaper, and the maximum refrigerant charge reduction can be up to 30%. The reduction of refrigerant charge can not only reduce the cost, but also improve the reliability of the whole system.

The COP of R410a refrigerant system can be 6% higher than that of R22 in the same cooling capacity and condensation temperature system. This is because the compressor in the compression process loss is lower, evaporator and condenser have stronger heat transfer, the whole system pressure drop is smaller. Efficient heat transfer and lower pressure drop make the condensation temperature lower and evaporation temperature higher under the same operating conditions, which makes the compressor obtain a better operating range with less power consumption and higher efficiency ratio. In addition, for the low compression loss characteristics of R410a, large compressors in small commercial air conditioning systems benefit more than small household air conditioning compressors.

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