When you usually go to the supermarket to buy yogurt or pick up cold drinks at a convenience store, you might not have noticed: inside those buzzing refrigerated display cabinets, there's a key component that determines the cooling effect and operating costs — the refrigerant.
A while ago, I helped my cousin, who runs a small supermarket at home, choose a display cabinet. He held two models and asked, "What's the difference between R600a and R134a, anyway?" That's when I realized that many people, even if they use display cabinets every day, are completely confused about refrigerants. Today, I'll explain refrigerants for refrigerated display cabinets from basic principles to practical selection, so whether you're choosing equipment for a store or using a small display cabinet at home, you can avoid detours.
First, understand this: Refrigerant is the "cooling blood" of a refrigerated display cabinet.
Simply put, refrigerant is the "heat transporter" that circulates in the display cabinet — under the action of the compressor, it absorbs heat and vaporizes in the evaporator (absorbing heat from inside the display cabinet to achieve cooling), then releases heat and liquefies in the condenser (releasing heat to the outside). This repeated cycle maintains the low temperature inside the cabinet.
For refrigerated display cabinets, the choice of refrigerant directly affects three core aspects: cooling efficiency (whether it can cool quickly and maintain a stable temperature), operating costs (power consumption, later maintenance fees), safety (whether it will leak, whether there is a risk of explosion/corrosion), and even environmental friendliness (impact on the ozone layer and the greenhouse effect).
In the past, many people thought "all refrigerants are the same; as long as they can cool, it's fine". But in reality, choosing the wrong one may lead to problems such as "the temperature inside the cabinet can't drop, drinks are never cold", "electricity bills are much higher than others", and even rare but dangerous leakage issues.
Common refrigerants for refrigerated display cabinets: 3 mainstream types + 1 obsolete type, comparison of advantages and disadvantages.
Currently, the refrigerants used in refrigerated display cabinets on the market mainly focus on 3 types, and 1 type has been explicitly restricted by the state. Let's clarify them for everyone first:
1. R600a (isobutane): The "mainstream choice" for small display cabinets.
Nowadays, more than 80% of vertical beverage cabinets in convenience stores and small yogurt cabinets in supermarkets use R600a. Its core advantages are obvious:
• Good environmental performance: Ozone Depletion Potential (ODP) is 0, so it won't damage the ozone layer; Global Warming Potential (GWP) is also extremely low, only 3. Compared with R134a, which will be discussed later, its impact on the greenhouse effect is almost negligible.
• High cooling efficiency: Under the same power, the cooling capacity of R600a is 10%-15% higher than that of old refrigerants. That is, when cooling to 5°C, it is more energy-efficient.
• Low cost: Raw materials are easily available, so display cabinets using R600a are usually 5%-10% cheaper than other types.
But it has a fatal disadvantage: it is flammable and explosive. R600a is a hydrocarbon. When exposed to an open flame (such as a lighter or cigarette butt) or an electric spark after pipeline leakage (such as an ungrounded socket), it may explode when the concentration reaches 1.8%-8.4%.
Therefore, display cabinets using R600a must meet two conditions: first, the cabinet must have a "leakage prevention + explosion-proof" design (such as installing a leakage detector and using an explosion-proof compressor); second, the installation location must be away from fire sources, and during maintenance, the power must be cut off first, and ventilation must be done to let the residual refrigerant dissipate before operation.
2. R134a (tetrafluoroethane): The "safety first choice" for large display cabinets.
Large island cabinets in supermarkets (such as those holding frozen dumplings) and large-capacity refrigerated cabinets in fresh food areas mostly use R134a. Its core advantage is high safety:
• Non-flammable and non-explosive. Even if the pipeline leaks, there is no risk of fire; moreover, it has stable chemical properties, will not corrode the compressor and pipelines, and can extend the equipment life by 2-3 years.
• Strong cooling stability: In the refrigeration range of -20°C to 5°C, the pressure change of R134a is small, and there will be no "temperature fluctuations". It is suitable for scenarios that require precise temperature control (such as display cabinets storing fresh food and vaccines).
But its shortcomings are also prominent:
• Average environmental performance: Although ODP is 0, GWP is as high as 1430, which is more than 400 times that of R600a, and has a greater impact on the greenhouse effect. However, the state has not yet restricted the use of R134a in refrigerated display cabinets, but requires that it be gradually replaced with refrigerants with lower GWP in the future.
• Slightly higher power consumption: For display cabinets of the same volume, those using R134a may have monthly electricity bills 10%-15% higher than those using R600a (calculated at a commercial electricity price of 1 yuan per kWh, a 100L display cabinet may cost 5-10 yuan more per month).
3. R290 (propane): The emerging "environmentally friendly alternative".
In recent years, newly launched high-end refrigerated display cabinets have begun to use R290 refrigerant. It can be said to be an "optimized version of R600a":
• Its environmental performance is slightly better than R600a, with a GWP of only 3. It has good compatibility with air and will not form toxic gases after leakage.
• Its cooling efficiency is about 20% higher than R134a. For display cabinets of the same capacity, power consumption is 15%-20% lower than that of R134a.
But like R600a, it is flammable and explosive, and has a wider explosion limit range (2.1%-9.5%), which requires higher equipment tightness and explosion-proof design. Currently, only a few first-tier brands in China (such as Haier and Xingxing) use R290 in their high-end display cabinets, which are 15%-20% more expensive than R600a models and have not yet been fully popularized.
4. R22 (difluoromonochloromethane): The obsolete "old model".
Many old display cabinets before 2010 used R22 refrigerant. However, its ODP is as high as 0.055, which will seriously damage the ozone layer. In 2020, the state has explicitly prohibited the production and sale of refrigerated display cabinets using R22. Now, only a small amount may be supplemented during the maintenance of old equipment (and this will also be gradually prohibited in the future).
If you still have an old display cabinet using R22 at home or in the store, it is recommended to replace it as soon as possible — on the one hand, it is difficult to buy R22 during maintenance, and the price is also expensive; on the other hand, the power consumption of old equipment is more than 30% higher than that of new models, so it is not cost-effective to use it for a long time.
Practical guide: How to choose, judge, and maintain?
After talking about the theory, here are some "practical suggestions" that you can use directly:
1. When choosing a display cabinet, first look at the "refrigerant type" and then match the scenario.
• If it's a convenience store or small supermarket, and you choose a small display cabinet (such as a vertical beverage cabinet) with a capacity of 100-300L: priority should be given to R600a models, which are cost-effective and energy-efficient, as long as you confirm that the equipment has an explosion-proof design.
• If it's a large supermarket or fresh food store, and you choose a large-capacity display cabinet (such as an island cabinet or fresh food cabinet) with a capacity of more than 500L: priority should be given to R134a models, which are safe and stable, and there's no need to worry about leakage risks.
• If you have sufficient budget and want to choose a more environmentally friendly one: you can consider R290 models, but be sure to choose big brands to ensure that the equipment's tightness and explosion-proof performance meet the standards.
2. How to know which refrigerant your display cabinet uses? Just check two places.
You don't need to disassemble the machine or ask a maintenance worker; you can check it yourself:
• Look at the nameplate on the machine: All refrigerated display cabinets will have a "product nameplate" pasted on the side or back, which will clearly indicate the "refrigerant type" (such as "Refrigerant: R600a") and filling amount (such as "Charge: 50g").
• Look at the instruction manual: The refrigerant model will also be marked in the "technical parameters" section. If you can't find the paper manual, search the brand's official website and enter the equipment model to find the electronic version.
3. Refrigerant doesn't need to be "replaced regularly"; it only needs to be refilled if it leaks, and you must find a professional.
Many people will ask, "How many years does a display cabinet need to have its refrigerant replaced?" In fact, as long as the equipment doesn't leak, the refrigerant is recycled and never needs to be replaced. Only in these two cases does it need to be handled:
• The display cabinet cools down slowly. For example, it used to be able to cool down to 5°C in 1 hour, but now it takes 2 hours, and the compressor keeps running non-stop.
• There is oil stains on the outside of the cabinet (when refrigerant leaks, it will carry frozen oil, forming oil stains).
In such cases, you must find a qualified commercial refrigeration maintenance worker: on the one hand, flammable and explosive refrigerants such as R600a and R290 are prone to accidents if operated by yourself; on the other hand, different refrigerants cannot be mixed (for example, adding R134a to equipment using R22 will cause compressor damage). Professionals will first detect the leakage point, repair it, and then replenish the refrigerant according to the model.
