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Propane as R22-Replacement in Commercial Appliances 

Heinz Jürgensen 

Danfoss Compressors GmbH 

D-24939 Flensburg 

h.juergensen@danfoss.de

Abstract 

Propane (R290) can be introduced in many of today’s R22 applications. No other single component 

refrigerant has such similar thermodynamic behaviour to R22. In climates characterized by high 

ambient temperatures, R290 provides improved performance in terms of discharge temperature and 

pressure. The experience built up over several years of production, mainly with commercial 

refrigerated appliances (ice cream freezers, commercial freezers/ refrigerators, ...), demonstrates that 

R290 is a promising alternative for R22, as components (e.g. compressors) are available in the market 

and R290 is compatible to the most commonly used heat exchangers and materials. However, 

application possibilities have been limited due to safety concerns. Safety standards for appliances are 

available, covering refrigerant charges up to 150 grams (g) per system. Appliance producers 

manufacturing R290 systems must be equipped accordingly, and service technicians must be trained in 

safe handling procedures. 

Background 

R22 is a widely used refrigerant. The demand for R22 equipment has been increasing, especially in 

developing country markets. Of particularly high demand are refrigerated appliances for small and mid 

size shops and restaurants at affordable costs. The appliances are mostly factory made plug-in units 

with hermetic refrigerant circuits—such as bottle coolers, ice cream freezers, commercial freezers/ 

refrigerators, beer coolers, and beverage dispensers. The companies manufacturing these appliances 

are often small compared to household appliance manufacturers, so existing equipment and personnel 

knowledge about refrigeration and safety standards are not always adequate. R22 is a well performing 

refrigerant in use in small refrigerated appliances, with the exception of applications with high 

discharge temperatures at low evaporation temperatures in freezers. In this application, R22 has 

replaced R502 as a result of the CFC phase out, although it is less suitable for freezers. In addition, 

R22 refrigerant and R22 components are available at low cost from many producers. Replacements for 

the refrigerant in these appliances should preferably be compatible with materials and basic 

technology already in use, such as tubing or brazing. The cost of these components is an important 

issue in choosing an HCFC alternative. 

Thermodynamic Comparison of R290 to Other Refrigerants 

High ambient temperatures and/or high humidity conditions add to the thermal load of a system and, 

therefore, some important points should be compared with regards to the suitability of various HCFC 

alternatives. For household and similar appliances, the design ambient temperature for tropical 

application is 43 °C, which is taken as reference here. This results in condensing temperatures of 

above 50 °C, and on MBP somewhat above 55 °C. 

Refrigerants taken into the comparison are R22, R290, R134a, R404A and R600a. Refrigerants with 

large temperature glide are not discussed. For the comparison two conditions were chosen, which 

represent operation of a commercial freezer display case and a bottle cooler at high ambient 

temperature. 

• LBP - Freezer evaporating/condensing/return (suction) gas at -35/50/20 °C 

• MBP - Bottle cooler evaporating/condensing/return (suction) gas at -10/55/20 °C 

For some comparisons the condensing temperature or return (suction) gas temperature are varied. 
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Table 1 provides a summary of the thermodynamics of R290 as compared to R22, R134a, R404A, and 

R600a under the chosen conditions.

Table 1: Performance of refrigerants at discussed conditions 

Item R22 R290 R134a R404A R600a 

Pressure o o + - + 

Pressure ratio low back pressure (LBP) o + - o - 

Discharge temperature - + + + + 

Volumetric capacity + + - + - 

Capacity loss o o o - o 

COP o o o - + 

Legend: 0 = acceptable; + = good; - = problematic.

Summing up the different thermodynamic aspects, R290 could be used as replacement for R22 in 

many commercial refrigerated MBP and LBP applications. R290 is the only candidate, which comes 

close to R22, in some aspects even outperforming it. The lower pressure ratio and lower discharge 

temperature even allow for use in certain applications where R22 is problematic. 

Bringing the alternative to market 

R290 has a long history in refrigeration. It has been in use since before CFCs were developed and was 

re-introduced for use in heat pumps after the CFC phaseout. Its thermodynamic data, efficiency, and 

material compatibility are well known. In some countries, appliance manufacturers and food producers 

began using R290 as a replacement for R404A or R134a in appliances shortly after 2000, due to 

environmental concerns. 

The increasing use of the flammable refrigerant isobutane (R600a) in household appliances 

demonstrated that it is possible to safely use flammable refrigerants, thus opening the possibility to use 

R290 in other systems. Indeed, compressors developed specifically for R290 have been available since 

2000. However, retrofitting R22 compressors to R290 often results in serious reliability problems for 

the appliance manufacturers. 

Commercialized applications with propane 

The commercial applications listed in Table 2, are sorted roughly in order of number of sold units. The 

large market of unitary air conditioners is not listed, as Danfoss is not producing propane compressors 

for such units. The market demand for R290 compressors has been growing over the years, but 

remains small relative to R134a or R404A. 

Table 2: Applications with small hermetic systems 

Bottle cooler MBP 

Ice cream freezer/commercial freezer LBP 

Commercial refrigerator MBP 

Beer cooler MBP 

Beverage dispenser MBP 

Dehumidifier HBP 

Electronics cooling HBP 

Heat pump HBP 

LBP=Low Back Pressure 

MBP=Medium Back Pressure 

HBP=High Back Pressure 

In short, the major applications for propane compressors will be in MBP and commercial and ice 

cream freezers with LBP. Unfortunately, increased capacity typically also requires increased 

refrigerant charge. Due to the limitations in safety standards, the cooling capacity is therefore limited, 

as long as standard system components are used. 

In 2000, Danfoss Compressors introduced a combined LBP/MBP compressor range for propane 

ranging from 5 to 21 cm3

. This range has been extended to 3 cm3, and by 12 to 21 cm3 pure LBP 

compressors with optimized valve systems, thereby increasing capacity. 
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Since compressors for propane are available, Danfoss Compressors together with customers have 

tested this refrigerant in several equipment types of different sizes, namely: 

• Bottle coolers 

• Beer coolers 

• Commercial freezers 

• Beverage dispensers 

• Small ice-cream freezers 

• Display island freezers and coolers 

Comparisons of propane compressors have been primarily made against R134a and R404A 

compressors, and to a lesser extent, R600a and CO2 compressors. The findings are that R290 

performed about the same as R134a, and typically better than R404A. Efficiency improvements were 

in the range of 0 to 10 %. 

In some cases, modifications were needed to reduce the charge size of R290 below 150 g. This was 

achieved by using different evaporator tube sizes and/or changes to capillary expansion. 

The capacity penalty of R290 relative to R404A in LBP applications was less than predicted, probably 

because of the lower pressure ratio of R290. 

Safety considerations 

Safety standards have been developed for the use of hydrocarbons, including leakage simulation tests 

and specifications for several electrical components which may come into contact with leaking 

refrigerants. The following set of international standards, from the International Electrotechnical 

Commission, on electrical safety contains rules for the design and testing of appliances operating with 

flammable refrigerants: 

• IEC 60335-2-24: Household refrigerators and freezers 

• IEC 60335-2-34: Motor compressors 

• IEC 60335-2-89: Commercial refrigerators and freezers 

• IEC 60335-2-40 : Heat pumps, air conditioners and dehumidifiers 

IEC 60335-2-24 and IEC 60335-2-89 currently restrict the charge size for commercial refrigerators 

and freezers and household refrigerators and freezers to 150 g of flammable refrigerant, respectively. 

This charge amount is considered to be safe if the appliance itself is tested for safety. The standard 

does not establish safety guidelines for units with a propane charge greater than 150 g. Thus, the use of 

R290 is normally limited to 150 g, which corresponds to a R22 charge size of 300-350 g. 

Guidelines for designing appliances for flammable refrigerants are available to meet the requirements 

of these safety standards. Many commercial refrigerated appliances use components suitable for 

flammable refrigerants, already meeting safety standard requirements. Larger appliances, which 

require a larger refrigerant charge size, need major modifications to be operated with 150 g, 

particularly to the evaporator volume and the liquid receiver used with thermostatic expansion valves, 

which determine the charge amount required. To reduce the charge size to 150 g, capillary expansion 

systems and small evaporator inner volumes must be applied, which requires significant development 

effort for larger appliances. 

Danfoss considers working according to safety standards for use of R290 essential and strongly 

recommends obtaining third party approval for the appliances and manufacturing, testing and charging 

appliances (e.g., TÜV), even in countries where approvals are not mandatory. In some countries, 

additional laws may apply to the use of flammable refrigerant. This must be investigated by the 

appliance manufacturer. 

In addition, safe work during servicing of appliances with flammable refrigerant requires well-trained 

and educated after-market service personnel. Depending on the country, the service technicians will 
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have very different backgrounds and education levels. Therefore, in terms of handling flammable 

refrigerants, this education must be brought to a safe level. 

Impacts of switch to alternative 

The production costs for appliances being converted from equivalent HCFC charge and using up to 

150 g R290, might slightly increase due to safety standard requirements. The actual cost increase 

depends on the changes necessary, and can often be minimized by some redesign of the equipment. 

The major impact on the producer will be the cost of equipment for leakage testing, charging, and 

safety installations in the factory. The cost of the necessary equipment is dependent on the production 

volume. 

The energy efficiency and reliability of the appliance using R290 is expected to be equivalent to or 

better than that of equipment using R22. Because R290 has no ODP and a very low GWP, assuming 

that R290 has the same energy efficiency as R22, the environmental impact is reduced. Based on 

estimated charge sizes and leak rates, emission savings are estimated to be 25 tonnes of R22 per 

100,000 appliances.