3 points about R404A Refrigerant, you know?
Due to the continuous use of environmentally friendly refrigerants and the continuous updating of various refrigerants, R404a refrigerants are widely used among environmentally friendly refrigerants. R404a refrigerant is a colourless gas at normal temperature and a colourless transparent liquid under pressure. This refrigerant is suitable for all operating environments and is closest to R-502. Now let’s introduce some related content about r404a refrigerant in detail.
1. R404A properties, application, and precautions
1) R404A is a mixed refrigerant with a vacuum before filling. Otherwise, if the mixing ratio changes, the effect will not achieve, and the equipment may even damage.
2) Non-flammable. R404A is a chlorine-free non-azeotropic mixed refrigerant and a colourless gas at normal temperature and pressure, which is a compressed liquefied gas stored in a steel cylinder. Its ODP is 0, so R404A is an environmentally friendly refrigerant that does not destroy the atmosphere’s ozone layer.
3) R404A refrigerant is an environmentally friendly refrigerant suitable for medium and low-temperature refrigeration.
4) It is normal for the low-pressure working pressure of R404 used for refrigerator refrigerant to be in the range of 4-6. R404A is a mixture of HFC125, HFC-134a, and HFC-143, a colourless gas at room temperature and a colourless transparent liquid under pressure. R-404A is suitable for new commercial refrigeration and transportation refrigeration equipment or updating the device at medium and low temperatures. Close to the operation of R-502, even can reach 15℉ (-9.4℃) or colder, this refrigerant is suitable for all environments where R-502 can operate normally.
5) R404 packaging: in daily sales, there are non-reusable steel cylinders of 10.9 kg, reusable steel cylinders of 400L/800L/926L/1000L, tank trucks of 18T, etc.
6) R404A storage and transportation
Refrigerant R404A steel cylinders are pressurized containers. They should be kept from fire, heat sources, and direct sunlight when storing. They are generally stored in a cool, dry, and ventilated warehouse.
7) R404A supporting the use of refrigeration oil
Generally, the refrigerating machine oils used with refrigerant R404A include: ICEMATIC SW32, SW220, EMKARATE RL32H, RL170H, etc.; what kind of refrigerating oil is finally used in different equipment and different application places should be under the regulations of the refrigerating compressor and refrigeration (air conditioning) equipment manufacturers Advise, or judge according to the specific conditions of the refrigeration compressor and refrigeration equipment, the use of refrigerator lubricating oil with the same design and technician requirements, that is, choose the equivalent refrigerator oil.
8) Refrigerant R404A is an industrial standard refrigerant (generally a low-temperature refrigeration system) that replaces Freon R22 and R502 on newly installed refrigeration equipment. R404A is the closest to the operation of R-502, and it is suitable for all R-502 that can operate normally. Environment, R404A is recognized and used by most refrigeration equipment manufacturers. However, R404A is different from R502 and R22 in physical and chemical functions, theoretical cycle functions, compressor oil, etc., for after-sales repairs of refrigeration equipment initially installed with R502 and R22 refrigerants, if the demand increases or the refrigerant is replaced, it is still a problem. Only adding R502 and R22, and generally, R404A cannot replace R502 and R22.
2. Problems to be considered when R404a replaces R22
In recent years, R404A has been widely used as a substitute for R22 more and more. Let’s introduce their differences and problems that need attention.
1) The big problem with using R404a refrigerant to replace R22 is the problem of lubricating oil. It is necessary to use PVE ester oil to replace mineral lubricating oil for R22. Ester lubricating oils have a high affinity with water and poor dehydration, so try to avoid contact with outside air during use. After opening the container, use it as soon as possible, and keep it sealed after use; keep away from oxidants, strong alkalis, and strong acids. Store in a well-ventilated place; avoid contact with skin and eyes, and avoid inhaling its vapour and spray during use.
2) The exhaust pressure of R404a refrigerant is about 1.2 times that of R22, the mass flow rate is about 1.5 times that of R22, the exhaust flow rate increases, and the resistance becomes larger. Generally speaking, the heat exchange capacity of the condenser is 20% to 30% larger than that of R22.
3) At the same temperature, the saturation pressure of R404a refrigerant is different from that of R22, so the action mechanism of the thermal expansion valve of R404a refrigerant is different from that of R22. At the same time, due to the different compatibility of R404a refrigerant and lubricating oil with the sealing material, the sealing material of the expansion valve should change accordingly. Therefore, the R404A special expansion valve should select in the selection of the thermal expansion valve.
4) For the same compressor, the current of R404a refrigerant is greater than that of R22, so the diameter of the AC contactor, thermal relay, and cable of the compressor should adjust. In terms of system protection, the setting value of the high-pressure switch is adjusted from 2.45MPa to 2.7MPa.
5) Since the saturation pressure of R404a refrigerant is different from that of R22, the air tightness test pressure should be greater than that of R22. At the same time, the vacuum degree of the system should be higher than that of R22, and the water content should be lower than that of R22. The refrigerant should be charged in liquid form to prevent the R404A configuration from changing.
6) R404a refrigerant is a non-azeotropic mixture. The concentration of the components of the non-azeotropic mixture changes with temperature and pressure, which brings certain difficulties to the production, commissioning, and maintenance of the refrigeration system, then affecting the thermal conductivity of the system. Especially when the refrigerant leaks, the refrigerant in the system needs to be completely emptied and replaced to ensure the ratio of each composite component and achieve the designed refrigeration effect; otherwise, it will get worse.
Since the R404A refrigerant and lubricating oil have good compatibility with water, the system’s moisture, residues, and cleanliness requirements are higher than those of the R22 refrigerant. R404A system moisture control and impurity control are the same. For the more important indicators, the corresponding filtering devices in the system need to be changed.
3. The difference between refrigerant R404A and R507
Refrigerants R404A and R507, two commonly used refrigerants in recent years, are suitable for high and low-temperature test chambers, constant temperature and humidity test chambers, thermal shock test chambers, and other equipment with low-temperature refrigeration systems. Let us briefly introduce their differences:
1) Refrigerant R404A is made by mixing R125/R143a/R134a at 44%/52%4%, and R507 is made by mixing R125/R143a at 50%/50%. Look at the three components of R404A have included the two components of R507. The ODP of both refrigerants is 0, neither of which will destroy the ozone layer.
2) The pressure of R404A and R507, the temperature and pressure gauge data show that the pressure between the two is almost the same and will not cause any impact on the system. Share the description if you usually pay attention to the system accessories, especially the mark on the expansion valve R404A and R507.
3) R404A is a non-azeotropic mixture and must be charged in a liquid state, while R507 is an azeotropic mixture.
4) The presence of R134a in R404A increases the mass transfer resistance. It reduces the heat coefficient of the transfer chamber, while the heat transfer coefficient of R507 is higher than that of R404A.
5) Judging from the current use results of the manufacturer, the cooling effect of R507 is indeed faster than that of R404A.
6) In terms of cost performance, R507 is 30–40% higher than R404A.
7) The performances of R404A and R507A are relatively similar. The compressor power consumption of R404A is 2.86% higher than that of R507A; the discharge temperature of the low-pressure compressor is 0.58% higher than that of R507A, and the discharge temperature of the high-pressure compressor is 2.65% higher than that of R507A; R507A is 0.01 higher; the intermediate temperature is 6.14% lower than R507A.
Above, we have introduced some knowledge of R404A; what else do you know about R404a? Comments and revisions are welcome!