Hydrocarbon refrigerants are traditionally widely used in petrochemical applications, where the use of flammable substances is well understood. However, as the refrigerants are generally available at low cost and have excellent thermodynamic properties superior to most HFCs, and are mineral oil compatible and chemically stable unlike most HFC refrigerants, their application outside the petrochemical area is rapidly growing.
Domestic refrigeration is an obvious application where safe systems are easy to achieve due to the small system charges (less than contained in a cigarette lighter, in many cases). Many small and medium commercial applications are also feasible with various hydrocarbon refrigerants, where safety requirements are adhered to.
Hydrocarbon refrigerants are flammable at concentrations between 2% and 10% concentration in air, and this characteristic of these refrigerants must be well understood and specific design and servicing techniques are required to overcome this challenge.
As with HFC refrigerants, copper pipe-work is suitable for most commercial applications. Mineral oils, which are available at low cost and do not exhibit the hygroscopic characteristics of synthetic oils, are well suited to hydrocarbon refrigerants. Hydrocarbon refrigerants are not as sensitive to moisture as are equivalent HFC or HCFC systems.
Hydrocarbon refrigerants can safely replace HFCs in most small and medium systems.
Immediate highly feasible applications include:
- Domestic refrigeration: Fridges, Freezers, Water dispensers
- Small A/C: Window rattlers, small split systems
- Water chillers: Water and air-cooled chillers, up to 200kW
- Supermarkets: High stage systems in combination with CO2 or secondary refrigerants
Examples of hydrocarbon refrigerants and their application:
- Streets ice cream cabinets
- Electrolux, Vestfrost, Miele, Liebherr domestic refrigerators (particular models)
- Benson Air Conditioning systems
Safe design with hydrocarbon refrigerants
The table below is an extract from AS/NZ 1677.1 which defines the safety requirements relating to the use of hydrocarbon refrigerant. System charge volumes are restricted to meet the zoning (A, B or C) and the system type restrictions.
However, restriction of charge quantities is not the only requirement to ensure safe use of hydrocarbon refrigerant. The procedure shown below (courtesy of Alex Pachai, Johnson Controls, Denmark) provides a guide to the requirements for safe design of hydrocarbon systems. Ventilation of the plant area, safe design of electrical system (spark-free), restricted access to plant area and other considerations are applied to achieve adequate levels of safety.
The graphic below (also courtesy of Alex Pachai, Johnson Controls, Denmark) illustrates the plant room requirements for hydrocarbon refrigeration systems required to comply with EN378.
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