Recently, Daikin Industries, Ltd. (Daikin) has taken a great step to encourage the use of HFC-32. As per a Wikipedia note: “HFC-32 Methylene Fluoride or R-32 is an organic compound of the dihalogenoalkane variety. It has the formula of CH2F2. It is a colorless gas in the ambient atmosphere and is slightly soluble in the water, with a high thermal stability. Due to the low melting and boiling point, (-136.0 0C and -51.6 0C respectively) contact with this compound may result in frostbite. As of September 1997, Clean Air Act- Section 111 on Volatile Organic Compounds (VOC) listed difluoromethane as an exception from the definition of VOC due to its low production of tropospheric ozone. Difluoromethane is commonly used in endothermic processes such as refrigeration or air conditioning.”

What Daikin has done now

Daikin has added 123 new patents to its pledge, which includes a grant of free access to its pledged patents in relation to certain HVAC-R (Heating, Ventilation, Air conditioning and Refrigeration) equipment using the non-blended, single-component refrigerant HFC-32 (R-32).

Approximately 300 patents are now free to use and do not require permission or a written contract with Daikin. As a result, the company will facilitate the further adoption of HFC-32, which has a lower global warming impact than many refrigerants commonly used today.

HFC-32 has many advantages that can help reduce the environmental impact of air-conditioning, heat pump, chiller, and applied equipment. This is a non-ozone depleting refrigerant with a Global Warming Potential (GWP) one-third of current R-410A refrigerant. It provides excellent system performance and is readily available. Also, as a single-component refrigerant, it is easy to recover, recycle and reclaim, which helps reduce the need for additional production of refrigerant. Therefore, Daikin believes HFC-32 is a suitable refrigerant to reduce environmental impact in many regions.

As per the Wikipedia note: “Difluoromethane is a molecule used as refrigerant that has prominent heat transfer and pressure drop performance, both in condensation and vaporization. This has a 100-year Global Warming Potential (GWP) of 675 times that of carbon dioxide, and an atmospheric lifetime of nearly 5 years. It is classified as A2L – slightly flammable by ASHRAE, and has zero Ozone Depletion Potential (ODP).  Difluoromethane is thus a relatively low-risk choice among HFC refrigerants, most of which have higher GWP and longer persistence when leaks occur.”

The note also states: “Difluoromethane is currently used by itself in residential and commercial air-conditioners in Japan, China and India as a substitute for R-410A. In order to reduce the residual risk associated with its mild flammability, this molecule should be applied in heat transfer equipment with low refrigerant charge such as brazed plate heat exchangers (BPHE), or shell and tube heat exchangers and tube and plate heat exchangers with tube of small diameter. Many applications confirmed that difluoromethane exhibits heat transfer coefficients higher than those of R-410A under the same operating conditions but also higher frictional pressure drops.”

A 3D model of Difluoromethane…

Former actions by the company

To encourage the use of HFC-32 globally, Daikin offered free access to 93 patents for emerging countries in 2011 and then expanded this free access worldwide in 2015. In July 2019, the company announced to provide free access to the pledged patents, which had been filed after 2011 and were not included in the previous free access to 93 patents.

Daikin intends to further facilitate the adoption of HFC-32 equipment by other manufacturers to promote the development of the environment by allowing free access to its intellectual property. As a result, many other manufacturers are already offering HFC-32 equipment, and more than 140 million HFC-32 residential and commercial units have been sold in approximately 100 countries.

Atmospheric concentration of difluoromethane at various latitudes since year 2009…

The company’s commitment

Daikin believes that expanding the scope of these patents will lead to further industry adoption. Interested readers can view a listing of the pledged patents and the specific details regarding the pledge at The company also assures that once listed, a pledged patent will not be removed, and the pledge will not be withdrawn against a party unless that party triggers Daikin’s right of defensive termination by, for example, filing a lawsuit or other legal proceeding alleging patent infringement against single-component HFC-32 equipment provided by Daikin or one of its group companies. For complete overview and explanation of the pledge, readers may refer to

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