Ammonia Refrigeration vs. Fluorine Refrigeration: Which is Better?

2025-03-09

In the refrigeration industry, ammonia refrigeration and fluorine refrigeration have always been the focus of people's debate. The choice of which refrigeration method can maximize economic, environmental, and social benefits. This article objectively analyzes the properties of ammonia and fluorine refrigerants as well as ammonia and fluorine refrigeration systems, and summarizes the application status, existing problems, and research directions of these two refrigeration methods in the industry, which is conducive to people's clear understanding of these two refrigeration methods.

Ammonia Refrigeration vs. Fluorine Refrigeration: Which is Better?1741450760168

Comparison of the Properties of Ammonia Refrigerant (R717) and Fluorine Refrigerants (R22 and R404A)
Safety: The explosiveness and toxicity of ammonia greatly limit its application. Moreover, with the frequent emergence of problem news about ammonia refrigeration systems in recent years, people have a certain fear of ammonia refrigeration systems. The high safety of fluorine refrigerants is the main reason for the rapid development of fluorine refrigeration systems in recent years.
Environmental Friendliness: The ODP (Ozone Depletion Potential) of ammonia is zero, and its GWP (Global Warming Potential) is also zero. R404A is a refrigerant that is relatively friendly to the environment, while due to its poor environmental performance, the application of R22 refrigerant will be restricted in developing countries before 2020. Currently, industry insiders are actively looking for more environmentally friendly alternative refrigerants.
Material Compatibility: When ammonia contains water, it is corrosive to copper. Therefore, copper and copper alloys cannot be used for the pipelines and valve components in the ammonia system, which has certain limitations in the selection of system device materials. Fluorine refrigerants have high chemical stability and thermal stability, and theoretically, they are not corrosive to all metals.
Interaction with Water: The allowable water content of ammonia is below 0.2%. Since ammonia is extremely soluble in water, even if there is a trace amount of water, it will not cause an "ice plug" like Freon.
Therefore, the requirement for the dryness of the pipeline system in the ammonia refrigeration system is not as strict as that for Freon. Freon is insoluble in water. Therefore, if there is water in the system, it is likely to cause an ice plug. Usually, a drier-filter is installed in the system.
Interaction with Oil: Currently, the lubricating oil used in ammonia refrigeration systems is mineral oil, which is not miscible with ammonia. Generally, equipment such as oil separators and oil collectors are installed, and the lubricating oil is returned to the compressor through automatic or manual control.
R404A cannot be miscible with mineral oil and alkylbenzene oil, but it can be miscible with polyester oil (POE). However, there is a phenomenon of immiscible stratification at high temperatures (around 50°C). At the same time, R22 is also slightly soluble in lubricating oil. Therefore, equipment such as oil separators and oil reservoirs are usually installed in large fluorine refrigeration systems.
Taking R404A as an example, the difference between these two compressors is only the refrigerant.
Compare the refrigeration capacities of R717, R22, and R404A under the same evaporation temperature (-10°C), condensing temperature (45°C), liquid subcooling degree (0K), and suction superheat (10K). Ammonia has more advantages than fluorine in terms of refrigeration capacity, COP (Coefficient of Performance), and mass flow rate. However, the discharge temperature of R717 is much higher than that of R22 and R404A, which will increase the requirements for the configuration of system components.
Ammonia has a much larger refrigeration capacity per unit mass than fluorine, indicating that ammonia has better refrigeration performance. However, when the evaporation temperature reaches -33.33°C, the gauge pressure of ammonia is 0. In order to avoid the system operating under negative pressure, ammonia is generally mainly used in systems with an evaporation temperature above -33.33°C.
System Complexity
Ammonia refrigeration is a pump liquid supply system. Since the mineral lubricating oil used in the ammonia refrigeration system is not miscible with ammonia, equipment such as oil separators and oil collectors are indispensable in the ammonia system to ensure the oil return of the system and reduce the system temperature, making the oil circuit system of the ammonia system very complex. All these make the ammonia system large, with many auxiliary machines, complex pipelines, many valves, complex construction, and a long construction period.
The fluorine system has a compact structure, occupies a small area, has few accessories, and the configuration of the unit is already very complete, and most of it can be completed in the factory of the unit supplier.
Equipment Investment
The ammonia system includes a large number of equipment, mainly compressors, evaporators, condensers, oil separators, high and low-pressure liquid storage tanks, intermediate coolers, re-coolers, ammonia liquid separators, low-pressure circulation barrels, emergency ammonia relief devices, air vents, oil collectors, ammonia pumps, and corresponding valve components and bypass valves, etc., resulting in a large amount of on-site installation work.
The main equipment included in the fluorine system are compressors, evaporators, condensers, oil separators, oil collectors, gas-liquid separators, liquid receivers, and corresponding valve components, etc. Generally, copper pipes or steel pipes are used in the fluorine system. The pipe connection is convenient, the pipe layout is simple, and the amount of pipelines used is less than that of the ammonia system.
Regarding the investment costs of ammonia and fluorine refrigeration equipment, under the same level of equipment quality and control mode, for small cold storage (compressor less than 50Hp), the equipment price of fluorine is more than 10% lower than that of ammonia. For large and medium-sized cold storage, the price difference is negligible. If imported or domestically assembled fluorine refrigeration equipment with imported components is used, it is more than 30% cheaper than imported ammonia refrigeration equipment, but it is 20%-30% more expensive than domestic ammonia refrigeration equipment.
Degree of Automation
Due to factors such as the valve material, processing equipment, and processing technology of the valve components in the domestic ammonia system, the leakage problem of the valve components in the ammonia system is serious, and it is difficult to achieve a high degree of automatic control. Special personnel are required to manage it 24 hours a day (Note: Now there are also automated ammonia storage facilities, but they are relatively few). Since the components of the fluorine system are mature in product quality and stable in performance, it is easy to achieve highly integrated and relatively stable automatic control, and basically achieve unattended operation of the system.
Due to the harm of Freon refrigerants to the atmospheric environment, the use of fluorine refrigeration has been limited to a certain extent in recent years. Therefore, actively searching for more ideal refrigerants is the development direction of fluorine refrigeration. People have made positive progress in the search for Freon alternative refrigerants. Some experts and scholars have pointed out that the better refrigerants to replace R22 are R407C, R410A, and R32, etc.
Conclusion
By comparing and analyzing the advantages and disadvantages of ammonia and fluorine refrigerants from the aspects of refrigerant properties and current application characteristics, it shows that ammonia refrigeration has better refrigeration performance. However, the toxicity and danger of ammonia are issues that we have to consider. Therefore, we need to continuously study and improve the objectively existing problems of the ammonia refrigeration system.
The better safety and simplicity of fluorine refrigeration are widely applied in small and medium-sized cold storage. Currently, there is also a trend of development towards large-scale applications. However, the harm of Freon to the atmospheric environment cannot be ignored. Therefore, finding a more ideal refrigerant remains the key focus and direction of future research.