What is the difference between R404A and R507 refrigerant?

2022/01/04

Refrigerant is the blood of the refrigeration system and is also called Freon in many places. It is an industrial substance that continuously circulates in the refrigeration system and realizes refrigeration through its own state changes. The refrigerant evaporates by absorbing the heat of the cooling medium (water or air, etc.) in the evaporator, and condenses by transferring the heat to the surrounding air or water in the condenser.

 

1.Refrigerant R404A and R507 are always used for low temp. refrigeration units, what is the difference between R404A refrigerant and R507A refrigerant?

 

(1)R507, like R404A, is an environmentally friendly refrigerant that can replace R502, but R507 can usually reach a lower temperature than R404A, and is suitable for new commercial refrigeration condensing units at medium and low temperatures (supermarket refrigeration cabinets, cold storage, display cabinets, transportation ), ice making equipment, transportation refrigeration equipment, marine refrigeration equipment or updating equipment, suitable for all environments where R502 can operate normally.

 

(2)The data on the pressure and temperature gauges of R404A and R507 show that the pressure between the two is almost the same. If you usually pay attention to the refrigeration system accessories used, you will find that the label instructions on the thermal expansion valve shows shared use by R404A and R507.

 

(3)R404A is a non-azeotropic mixture. Liquid filling is used when filling, while R507 is an azeotropic mixture. The presence of R134A in R404A increases the mass transfer resistance and reduces the heat coefficient of the transfer chamber, while the heat transfer coefficient of R507 is higher than that of R404A.

 

(4)Judging from the current refrigeration manufacturer’s use results, the effect of R507 is indeed faster cooling than that of R404A. In addition, the performances of R404A and R507 are relatively close, the compressor power consumption of R404A is 2.86% higher than that of R507, the discharge temperature of low-pressure compressor is 0.58% higher than that of R507, and the discharge temperature of high-pressure compressor is 2.65% higher than that of R507. COP is 0.01 higher than that of R507, and the intermediate temperature is 6.14% lower than R507.

 

(5)R507 is an azeotropic refrigerant with a lower slip temperature than R404A. After leaking and charging several times, the composition change of R507 is smaller than that of R404A, the volumetric cooling capacity of R507 is basically unchanged, and the volumetric cooling capacity of R404A is reduced by about 1.6%.

 

(6)Using the same compressor, the cooling capacity of R507 is 7%-13% larger than that of R22, and the cooling capacity of R404A is 4%-10% larger than that of R22.

 

(7)The heat transfer performance of R507 is better than that of R404A regardless of whether it contains lubricating oil or without lubricating oil.

2.How to Choose Suitable Refrigerant?

 

(1)Consider the requirements of environmental protection.

The refrigerant must be selected in compliance with national environmental protection regulations.

 

(2)Consider the requirements of refrigeration temperature.

According to different refrigerant temperature and cooling conditions, high temperature (low pressure), medium temperature (medium pressure), and low temperature (high pressure) refrigerants are selected. Usually the standard evaporating temperature of the selected refrigerant is 10°C lower than the refrigerating temperature. The choice of refrigerant should also consider the cooling conditions and use environment of the refrigeration device. The condensing pressure during operation should not exceed the specified value of the compressor's safe use conditions. Automobile air conditioners can only use the air outside the car as the cooling medium, the temperature, wind speed, solar radiation, heat radiation and other factors that affect it frequently chang, so its operating conditions determine that it can only use high-temperature (low-pressure) refrigerants. In the past R12 is used, and R134a is mostly used now.

 

(3)Consider the nature of the refrigerant.

According to the thermal, physical and chemical properties of the refrigerant, select those non-toxic, non-explosive, non-combustible refrigerants; the selected refrigerant should have good heat transfer, low resistance, and good compatibility with the materials used in the refrigeration system.

 

(4)Consider the type of compressor.

Different refrigeration compressors, work differently. Volumetric compressors increase their pressure by reducing the volume of refrigerant vapor, generally refrigerants with large refrigeration capacity per unit volume are used, such as R134A, R22, etc. There are many types of refrigerants, with the advancement of science and technology, new working fluids are constantly appearing to suit different refrigeration devices.