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

Daikin has assessed various refrigerants (R-32, blends, natural refrigerants, HFO, etc) based on four criteria (environmental impact, energy efficiency, safety and cost-effectiveness), and we have applied some of these refrigerants in selected applications. After examining its key properties, Daikin has concluded that R-32 is a better refrigerant than others for direct expansion type cooling and heating equipment (including single package products), and we have been launching R-32 products into the worldwide market region-by-region.

Smaller Impact on Environment

R-32 has zero ODP (Ozone Depletion Potential) and its GWP (Global Warming Potential) is 675, which is lower than the GWP of currently used R-410A or R-22. It could reduce the charging volume by 30% compared to R-410A. R-32 related CO2 emissions decrease by 76% thanks to the lower GWP and the charging volume reduction.

Theoretical Modified GWP

Theoretical Modified GWP

Energy Efficiency: High Energy Efficiency

The potential refrigerating effect of R-32 is 1.5 times that of 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.


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 16358-1.
  3. The peak power consumptions are based on indoor/outdoor temperatures of 27/35°CDB.
  4. Comparison among India, Indonesia and Malaysia.

Safety: Flammability

International Standard ISO 817:2014 segregates the flammability of refrigerants into 4 categories as follows: Class 1 (no flame propagation), Class 2L (lower flammability), Class 2 (Flammable) and Class 3 (higher flammability). 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.
We have done actual as well as theoretical risk assessments using refrigerant in equipment to confirm safety.

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(2090), 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

Relationship between Burning Velocity and GWP

Safety Group Classification 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

Behaviour of Flames

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

Classification Class 3 Class 2 Class 2L
A3 A2 A2L B2L
Substance Propane R-152a R-32 Ammonia
GWP 3 124 675 0
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

Source (https://www.daikin.com/csr/information/influence/hfc32.html)