HC-290-Propane as an Alternative Refrigerant

Vol-41 ? ? ? ? ? ? ? ? 18th November,2023

R290 (propane) can also be used as a substitute refrigerant. Being an organic compound (hydrocarbon), it has no ozone depletion potential and a negligible direct global warming effect. To take into consideration however, is a certain contribution to summer smog. Pressure levels and refrigerating capacity are similar to R22, and its temperature behaviour is as favourable as with R134a.

HC-290-Propane

There are no particular problems with materials. In contrast to NH3, copper materials are suitable as well, so that it can be used in semi-hermetic and hermetic compressors. Common mineral oils of HCFC systems can be used here as a lubricant over a wide application range. Polyol esters (POE) and polyalpha olefins (PAO) offer even more favourable properties.

Refrigeration plants with R290 have been in operation world-wide for many years, mainly in industry – it is a "proven" refrigerant. Meanwhile R290 is also used in smaller compact systems with low refrigerant charges like residential air-conditioning units and heat pumps. Furthermore, a rising trend can be observed in its use with commercial refrigeration systems and chillers.?

Propane is offered also as a mixture with isobutane (R600a) or ethane (R170), in order to provide a performance similar to halocarbon refrigerants. Pure isobutane is mostly intended as a substitute for R12 in small systems (preferably domestic refrigerators and freezers).

The disadvantage of hydrocarbons is their high flammability, therefore they are classified as refrigerants of safety group A3. Based on the refrigerant charges commonly used in commercial systems, the system design and risk analysis must be in accordance with explosion protection regulations. Semi-hermetic compressors in so-called "hermetically sealed" systems are in this case subject to regulations for hazardous zone 2 (only seldom and short term risk). Safety demands include special devices to protect against excess pressures and special arrangements for the electrical system. In addition, measures are required to ensure hazard free ventilation to effectively prevent a flammable gas mixture in case of refrigerant leakage.

Most of the food transport trucks in India are equipped with refrigeration and air conditioning systems filled with fluorocarbon refrigerants such as R404A to facilitate the heat transfer process. These refrigerants are synthetic chemicals and have high potential to cause global warming and damage to the ozone layer. Currently, natural refrigerants are considered as alternatives to these man-made refrigerants to mitigate some of the environmental risks. The natural refrigerants are the substances that occur in nature such as hydrocarbons (HC), ammonia, and carbon dioxide. These types of refrigerants have been in the market for many years, but in some applications such as domestic refrigerators, heat pumps, chillers, and air conditioners, whereas fluorocarbons are the mostly used in the food transport refrigeration systems. Natural refrigerants such as propane (HC – 290) are now penetrating the market in food transport refrigeration systems where previously fluorocarbons were the favoured option. Therefore, the possibilities of using non-fluorinated hydrocarbon/natural refrigerant (propane – R290) in the food transport refrigerated systems in India are being explored.

Conclusion

R290 has the potential to lower greenhouse gases emissions compared to hydrofluorocarbons (HFCs) which are widely used in most of the existing food transport refrigeration systems.R290 has negligible Global Warming Potential (GWP) of 3 which is well below the global threshold value of 150. The review revealed that refrigeration capacity of R290 is on average of 10 – 30% higher than commonly used fluorocarbon refrigerants such as R404A and R134A. Since R290 is labelled as a flammable refrigerant, flammability safety measures need to be undertaken.