Efficiency comparisons between hydrocarbons and fluorocarbons

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Contrary to HFC industry claims, systems using natural refrigerants are often more energy efficient than those using HFCs. Of course, there are many factors to be considered when comparing the efficiency of cooling equipment, but many studies have revealed  systems using natural refrigerants are among the most efficient available.

Table: Efficiency comparison between hydrocarbons and fluorocarbons

Application

Reference

Notes

Domestic refrigeration

 

 

Efficiency of hydrocarbons in domestic refrigeration

In 2005–2006, “the Danish Electricity Saving Trust conducted a campaign where 1000 DKK (approximately $200 US) were given to customers buying ‘“A++’ refrigerators and freezers (the most energy efficient models in the European labeling specification).” Among the 78 different appliances approved for inclusion in the campaign, 100% were based on hydrocarbon technology.[1]

Residential air-conditioning

Efficiency of hydrocarbons in residential air-conditioning in comparison to HCFC-22

A 2007 comprehensive enquiry into the use of hydrocarbons in residential air-conditioning has shown an energy efficiency increase of up to 5.7% over R22.[2] This is accompanied with a decrease in refrigerant charge of up to 55% because of the smaller density of hydrocarbons.[3]

Residential air-conditioning

DeLonghi

The Italian manufacturer De’Longhi produces small AC systems using propane as refrigerant. The cooling capacity ranges from 500 to 3,200 W, and the refrigerant charge is 100–500 g. The systems are found to have 5–10% higher efficiency than with HFCs.[4]

Residential air-conditioning

Gree

Gree has developed a high efficiency propane (R-290) domestic air-conditioner with a COP of 3.52-3.55 and energy efficiency 15% better than corresponding HCFC-22 units, and a total hydrocarbon charge of less than 300g.

Gree also produces hydrocarbon portable air-conditioners and dehumidifiers. The company reports 10% efficiency gains with the portable A/C units and 20% efficiency gains with the dehumidifiers. (See Section D)

Refrigerants

Efficiency of new hydrocarbon blends

2008 studies with new hydrocarbon blends, such as R-433A[5] (30% propylene, 70% propane) and R-432A[6] (80% propylene, 20% dimethylether), have shown increases in energy efficiency of up to 7.6% and 8.7%, respectively (both these blends are commercialized by Korean manufacturer MK Chemical).

Refrigerants

Survey of studies

comparing COPs of hydrocarbon and HFC refrigerants

A study analyzed various papers to draw comparisons between hydrocarbons and F-gas refrigerants. They found that in 90% of the cases reviewed hydrocarbons offered higher COPs than their F-gas counterparts, with an average improvement of 10% of the COP.[7]

Refrigerant comparisons

COPs of refrigerants in refrigeration systems

“Cool Pack”, is a calculation tool developed by the Danish Technical University to analyze energy efficiency. It contains thermodynamic properties for different refrigerants and algorithms for calculation of refrigeration systems.[8]

Refrigerant

COP (T0=-100C, TC=+350C)

COP (T0=+50C, TC=+450C)

R134a

2.78

3.30

R404A

2.53

2.94

R407C

2.71

3.15

R410A

2.65

3.05

R717 (ammonia)

2.82

3.41

R290 (propane)

2.74

3.25

R600a (isobutane)

2.80

3.36

R1270 (propylene)

2.73

3.21

 

HCFC-22 replacements

Comparison of HFCs and hydrocarbons as replacements for HCFC-22

HFCs, compared with hydrocarbons, are seen as poor substitutes for HCFC-22 in heat pumps. “For example, the critical temperature of HFC-R410A is only 72°C, far less than for the previous generation HCFC-R22, which had a critical temperature of 96°C. However, propane, R290, has a critical temperature of 97°C, making it the ideal replacement for heat pump applications that would previously have used R22.”[9]

HCFC-22 replacements

R-22 installations

Retrofitted with propane

Conversions of R-22 installation to propane typically report 15–20% energy savings. See Section C.2 of this report.

Air-conditioning

Comparison of hydrocarbons and fluorocarbons in compression refrigeration systems

In a 2008 study on a vapor compression refrigeration system (the most widely used method in refrigeration and air-conditioning today), a blend of R290 and R600a (propane and isobutane) gave an increase in energy efficiency of up to 25.1% at low temperatures (circa -18oC) and up to 17.4% at higher temperatures (circa +2oC).[10] This was compared with CFC-12. R134a was even less efficient than R12.

Ice cream freezers

Unilever

By 2009 Unilever had placed over 400,000 hydrocarbon ice-cream coolers around the world, including South Africa, China, Europe, Brazil, and the United States. These coolers contain approximately 100 g of hydrocarbons and have a 9% energy savings over their HFC counterparts.[11]

Restaurant Equipment

McDonald’s

In 2003, McDonald’s opened, as a pilot project, the world’s first HFC-free restaurant in Vejle, Denmark. The company reported that “according to TEWI calculation, during summertime (4 months) / wintertime (8 months) the emission (kg-CO2) from the restaurant in Vejle were 19%/32% lower than the conventional [HFC based control] restaurant in Esbjerg. The company projected that the lifetime emissions from the Vejle restaurant cooled by natural refrigerants “will be approximately 27% lower.” [12]

Commercial Food Refrigeration

Foster

This UK-based company has been producing hydrocarbon-based commercial refrigeration equipment since 1996. Reports up to 15% energy savings with natural refrigerants in standalone equipment.

Commercial Refrigeration

True Manufacturing (USA)

True Manufacturing currently offers self-contained refrigerators and freezers with less than a 150-gram charge of R290 to foodservice and beverage customers throughout the EU.True’s line of Natural Refrigerant units consume up to 15% less energy than standard HFC systems.[13]

Supermarket

Waitrose

Waitrose Supermarket of UK has announced plans to only use hydrocarbons in all new refrigeration. Designed to EN 378, the company is using a hydrocarbon-chilled water circuit (at 10° C) with water-cooled condensing units in display cabinets. The company reports 20% energy savings.


[1] Pedersen, Per Henrik, Danish Technological Institute, “Low GWP Alternatives to HFCs in Refrigeration”. 2012: p. 29

[2] Cox, N., (2006) “Sustainable Cooling: Refrigerants Beyond the Crisis”, presented to the EU Commission, Brussels, Belgium

[3] Mani K, Selladurai V, ‘Experimental analysis of a new refrigerant mixture as drop-in replacement for CFC12 and HFC134a’, International Journal of Thermal Sciences (2008)

[4] http://www.unilever.com/ourvalues/environment-society/case-studies/climate-change/hydrocarbon-ice-cream-cabinets.asp

[5] UNEP DTIE OzonAction : HCFC Help Centre : www.unep.fr/ozonaction/topics/hcfc_case-studies.htm : McDonalds’: world’s first free HFCs restaurant.

[6] Greenpeace correspondence with True Manufacturing, April 2012.

[7] TemaNord, 2007 : “Potent Greenhouse Gases: Ways of Reducing Consumption and Emission of HFCs, PFCs & SF6” : report prepared for the Nordic Council of Ministers

[8] Park K.J., Jung D “Thermodynamic performance of HCFC22 alternative refrigerants for residential air-conditioning applications”, Energy and Buildings (2007), 675-680

[9] Maclaine-cross I.M, Leonardi E, “Why do hydrocarbons save energy?” Australian AIRAH Journal 51 (1997) 33–37.

[10] Supra no.1, private communication with Aloisi A., De’ Longhi, 2007

[11] Park K.J. et al. “Performance of R433A for replacing HCFC22 used in residential air-conditioners and heat pumps” Applied Energy 85 (2008) 896–900

[12] Park K.J. et al. “Experimental performance of R432A to replace R22 in residential air-conditioners and heat pumps” Applied Thermal Engineering (2008)

[13] D. Colbourne and K. O. Suen, (2000) “Assessment of Performance of Hydrocarbon Refrigerants”