At present, the whole society is paying more and more attention to the environmental protection problem. In some areas, the relevant functional departments of the government have issued a comprehensive ban on fluoride. However, the ban on fluoride is not only the wrong concept, but also the confusion of the users and manufacturers. This article from the concept of Freon, international conventions, national policies, application characteristics of the common refrigerant R22 and R134a to do a comprehensive analysis to clarify the advantages of refrigerant R22.

First, the concept of freon

At present, many domestic manufacturers require manufacturers to use R134a and other environmentally friendly refrigerant, refused to use the Freon R22 refrigerant, the reason is in response to national calls to protect the environment. In fact, R22 and R134a are members of the freon family, belonging to the hydrochlorofluorocarbons. Freon is a generic term for halogen derivatives of saturated hydrocarbons (hydrocarbons). From the definition of Freon can be seen, now people called the environmental refrigerant R134a, R410A and R407C and so on are all belong to the freon family. So the concept of the ban on the ban on the contents of the ban can not be confused.

Freon has been able to destroy the ozone layer because the refrigerant contains CL elements, and with the increase in the number of CL atoms on the ozone layer also increased the ability to damage, with the H element content increased damage to the ozone layer decreased; the greenhouse effect is mainly due to Refrigerants in the slow oxidation process, generate a lot of greenhouse gases, such as CO2 and so on. According to the different molecular structure, freon refrigerant can be divided into the following three categories:

1. Chlorofluorocarbons: referred to as CFC, mainly including R11, R12, R113, R114, R115, R500, R502, etc., because of its destruction of the ozone layer is the largest, the "Montreal Protocol" as a class of controlled substances. Such substances are now being banned by our country.

2. HCFCs, referred to as HCFC, mainly including R22, R123, R141b, R142b and so on, the ozone layer destruction coefficient is only a few percent of R11, therefore, "China ODS phase-out country program" HCFC substances The most important transitional alternative to CFCs.

3. Hydrofluorocarbons: referred to as HFC, including R134a, R125, R32, R407C, R410A, R152, etc., the ozone layer failure coefficient of 0, but the higher the potential value of climate warming.

All of the refrigerants (including environmentally friendly refrigerants) currently used in our country are all freon products, and the ideal nonfluoro refrigerant has not been developed so far. Before the new refrigerant developed, we have to solve the air conditioning unit to use the kind of refrigerant, the environment for our survival caused by the destructive force is relatively small.

II. International conventions and "country programs"

The Global Cooperation Initiative for the Protection of the Ozone Layer began with the consultation and conclusion of the Vienna Convention for the Protection of the Ozone Layer in 1985. At the initiative of the United Nations Environment Program, the Montreal Protocol on Ozone Depleting Substances was signed in 1987, which entered into force on 1 January 1989, followed by the London Amendment (1990), the Copenhagen Amendment (1990) 1992), the Vienna Act (1995) and the Beijing Amendment (1999). In order to prevent climate warming, the United Nations Environment Program (UNEP) established the International Consultative Organization on Climate Change in 1988 and convened the third Kyoto meeting in Japan in December 1997 to form a resolution to reduce greenhouse gas emissions. The following table summarizes the motions:

International conventions on CFCs, HCFCs, HFCs

International regulations CFCs HCFCs HFCs

Montreal Protocol Montreal Protocol Kyoto Protocol

Developed countries

1996.1.1 Prohibition of production and consumption Reduction of 35% in 2004

2010 minus 65%

Reduced by 90% in 2015

Prohibited in 2020

2030 years ago can be used as a supplement, can produce 0.5% of the base year 2008 - 2012 average reduction in emissions 5.2%

developing

Country 2010.1.1 Prohibits Production and Consumption 2016.1.1 Consumption is frozen at the 2015 level

2040.1.1 Prohibition of consumption

USA 1996.1.1 Prohibited Production and Consumption 2010.1.1 Freeze R22 and R142b

Production, prohibition of the production of new equipment R22

2015.1.1 Freeze R123 and R124 production

2020.1.1 Disable R22 and R141b,

Prohibit the production of R123 and R124 new equipment

2030.1.1 Disable R123 and R124

EC 1996.1.1 Prohibition of production and consumption 2000.1.1 year reduction of 50%

Reduction of 75% in 2001.

2007 1. 1 year minus 90%

Redeem 100% for 1 year

From the above table, the developed countries from 2004 to begin to reduce the production and consumption of R22, China's task is to freeze consumption in 2016 in 2015 level. It will not only be able to continue to consume HCFCs (including R22, R123 and R141b, etc.) by 2015, but also to expand the production and consumption of HCFCs until 2040 to ban the consumption of HCFCs, including R22. It should be clear here that the timetable for HCFCs refrigerants such as R22, R123 and R141b is different for developed countries and developing countries to phase out and limit.

The Chinese government approved the implementation of the "China Ozone Depleting Substances Phase-out Country Program" (hereinafter referred to as the "National Program") in January 1993 to effectively control the production and consumption of China's ODS by implementing the "country program" , The establishment of the Multilateral Fund project management system for the implementation of the Montreal Protocol on Substances that Deplete the Ozone Layer and the implementation of the ban on the use of chlorofluorocarbons in the aerosol industry (except for products without alternative technologies) Chlorofluorocarbons, hereinafter referred to as CFCs), laid the foundation for further compliance with China. According to the demand for ODS substitutes in China, the consumption demand for HCFC-22, HCFC-141b, HFC-134a, isobutane and cyclopentane, which are the main alternatives to China's future, should be gradually adopted by the domestic production strategy. Estimates, and accordingly developed a replacement production plan, see the table below.

Alternative production plan (tons / year)

Alternative 1999 2005

HCFC-22 15000 33000 45000

HCFC-141b 2500 5200 12000

HFC-134a 2000 11000 20000

HFC-152a 130 160 200

Isobutane 80 100 120

Cyclopentane 1100 1400 1800

Butane 850 3300 4400

Pentane 400 2700 9500

Dichloromethane 650 4600 44000

Butane 60000 70000 80000

According to the "country program" is not difficult to see, in the future for a long period of time, HCFC-22 (R22) in the air conditioning, refrigeration industry will continue to play a very important role, the various media called for the ban on the use of fluoride Carbonized substances, rather than HCFCs, HFCs.

Third, R22 and R134a application characteristics of the difference

It is very difficult to choose a suitable refrigerant substitute, and many factors must be considered and evaluated in a comprehensive manner to meet the requirements of ODP, GWP and Consider thermal performance, toxicity, flammability, compatibility, investment and operating costs. The following application characteristics of R22 and R134a are analyzed as follows:

1, R134a's global warming potential (GWP) is 0.25, R22 is 0.36, belong to greenhouse gases.

2, R134a ozone depletion potential (ODP) is 0, R22 is 0.06, which is R134a as environmentally friendly refrigerant reasons.

3, R134a specific capacity is R7 1.47 times, and the latent heat of evaporation is small, so R134a unit refrigeration capacity of only R22 unit 60%. According to the unit cooling capacity calculation, R22 unit price is about R134a unit about 60%.

4, R134a thermal conductivity than R22 decreased by 10%, so R134a unit heat exchanger heat transfer area needs more.

5, R134a is very strong water absorption, R22 is 20 times, so the unit system dryer requirements are higher, in order to avoid the occurrence of ice blocking phenomenon.

6, R134a than R22 on the rubber material swelling effect is strong, in the actual operation of the refrigerant leakage rate is high. In addition to the corrosion of copper is strong, the use of the process will occur "copper phenomenon", so the system must add additives.

7, R134a system requires a dedicated compressor and a dedicated lipid lubricants, lipid lubricants because of high water absorption, high foaming and high diffuse, the stability of the system performance is inferior to the R22 system used mineral oil.

8, R134a and other HFCs refrigerant and its special grease prices higher than the R22, equipment, operation and maintenance costs higher.

Other refrigerants, such as R410A, R440A, R407C, which are known as environmental refrigerants, are superior to R134a in terms of efficiency. However, there is also a high working pressure, which is highly desirable and resistant to piping components. Heat exchanger and unit design, investment operation and maintenance costs and other shortcomings in the application of large refrigeration units at this stage is not suited to China's basic national conditions, which is the international conventions on the relaxation of the use of HCFCs in developing countries, the reasons for the development of National collective efforts to strive for results.

In summary, in the short term the ideal refrigerant is not present, in our country at this stage R22 refrigerant and R134a class of environmentally friendly refrigerants, still has the advantages of high efficiency, stability, low cost, in the application of large refrigeration units Will also be in a dominant position, in the ideal refrigerant before the birth, R22 refrigerant can also be consumed to 2040 years.