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Daikin's Policy and Comprehensive Actions on the Environmental Impact of Refrigerants

When selecting new refrigerants, comprehensive assessment from various perspectives is necessary. Any substance must be carefully evaluated for the overall impact on the global environment. It must also be assessed for energy efficiency, cost-effectiveness, safety and other factors. As recent studies have confirmed, there is no one perfect refrigerant adaptable to all applications. For the above reasons, it is necessary to focus on selecting the right refrigerants for particular applications based on an overall assessment.

R-32: The Most Balanced Refrigerant for Stationary Air Conditioners and Heat Pumps

The Most Balanced Refrigerant for Stationary Air Conditioners and Heat Pumps

According to Daikin’s research, HFC-32 (here in after called R-32) is considered to be the most promising substance for use as a next-generation refrigerant in both residential and commercial air conditioners. Daikin was the first to introduce air-conditioning and heat pump technology utilizing R-32, starting in Japan in November 2012. Today, Daikin and many other manufactures have already installed millions of R-32 units worldwide, resulting in substantial direct and indirect climate benefits as well as significant energy savings for the end user.

Smaller Impact on Environment

R-32 has only about one-third the GWP of currently used R-410A or R-22. It also improves the energy efficiency of equipment by 10% and could reduce the charging volume by 30% compared to R-410A. R-32 offers favorable GWP and lower charging volume. R-32 related CO2 emissions decrease by 76% thanks to the lower GWP and the charging volume reduction.

Theoretical Modified GWP

Note: GWP values are based on the Fourth Assessment Report from the Intergovernmental Panel on Climate Change (IPCC 4th AR).

Energy Efficiency of R-32

The potential refrigerating effect of R-32 is 1.5 times that of R-22 or R-410A. More specifically, pressure losses are lower with R-32 than R-22 or R-410A for the same capacity and the liquid density of R-32 is also 10% lower. Thus the piping diameter can be smaller. As a result, the charging volume can be 30% less than with R-22 or R-410A. The cooling seasonal performance factor (CSPF) of R-32 is higher than conventional refrigerants. Its peak power consumption is also lower, helping to alleviate power shortages in large cities during periods of high demand.

Refrigeration Cycle of R-32

Cooling Seasonal Performance Factor (CSPF) and Peak Power Consumption Ratio for Split Systems in Asia


Peak Power Consumption Ratio

Preconditions for calculations

1. 3.5 kW split-type cooling only model

2. CSPFs are calculated based on ISO/DIS16358-1.

3. The peak power consumptions are based on indoor/outdoor temperatures of 27/35°CDB.

4. The Asian region includes India, Indonesia and Malaysia, but not China.

Flammability and Safety

International Standard ISO 817:2014, segregates the flammability of refrigerants into 4 categories as follows: - no flame propagation (Class 1), lower flammability (Class 2L), flammable (Class 2) and higher flammability (Class 3). In general language these classifications are called Non Flammable, Mildly Flammable, Flammable and Highly Flammable. R-32 falls into the “lower flammability” or Class 2L "mildly flammable" category.

Under ISO 817, any refrigerant and air mixture that is capable of self-propagating a flame falls into one of the three flammable categories. Class 2L refrigerants present the lowest risk of the 3 flammable categories and are defined by having a burning velocity of less than 10 cm per second. The characteristic of this low burning velocity is that the flame front does not propagate readily in a horizontal direction. This is because the convection rise due to combustion creates a higher velocity than the burning velocity. This effectively means that a Class 2L refrigerant is not explosive if ignited because the flame only propagates in an upwards direction from the ignition point and not rapidly outwards in all directions.

ISO 817-2014 Safety Group Classification

  Flammability   Low Toxicity A   High Toxicity B
Class 3 Higher flammability A3 Propane, Isobutene, Others B3 n/a
Class 2 Flammable A2 R-152a B2 R-40, R-611
Class 2L Lower flammability A2L R-32(675), R-1234yf(4), R-1234ze (E)(6), Others B2L Ammonia
Class 1 No flame propagation A1 R-410A(675), R-134a(1430), R-407C(1770), Others B1 R-123, R-245fa

A2L and B2L are lower flammability refrigerants with a maximum burning velocity ≤ 10 cm/s (3.9 in./s)

GWP value is indicated in parenthesis based on IPCC 4th AR.

Relationship between Burning Velocity and GWP

BV is indicated in parentheses.

Source: Japan Refrigeration and Air Conditioning Industry Association (JRAIA)

Risk Assessment of Mildly Flammable Refrigerants 2013 Progress Report, April 2014, The Japan Society of Refrigerating and Air Conditioning Engineers

Behavior of Flames

Classification Class 3 Class 2 Class 2L
A3 A2 A2L B2L
Substance Propane R-152a R-32 Ammonia
Burning velocity 39 cm/sec 23 cm/sec 6.7 cm/sec 7.2 cm/sec
Heat of combustion 46 MJ/kg 16 MJ/kg 9 MJ/kg 19 MJ/kg
Combustion state

2L refrigerants do not horizontally propagate due to their slow BV. Additionally, heat of the combustion of R-32 is low and the range of any impact by its flame is limited.

Related information is available at the AREMA (The Air Conditioning and Refrigeration Equipment Manufacturers Association of Australia) homepage.

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