REFRIGERANTS | PROPANE SWITCHING TO PROPANE Propanes low GWP is making it an increasingly attractive alternative to refrigerants restricted by the F-gas Regulations. Tim Dwyer tracks the growth of propane and looks at the L150 initiative in Germany that is aiming to reduce the charge in a propane refrigerant circuit T he reduction in fluorinated greenhouse gases (F-gases) used in refrigeration is seen as essential if Europe is to meet its carbon-reduction targets. In a recent assessment report on the progress of the F-gas Regulation in Britain1, it was concluded that there had been success in achieving the objective to reduce emissions, as well as significant financial benefits. As explored in this months CPD article (page 61), this success is mainly the result of the hydrochlorofluorocarbon (HFC) phasedown and the transition from high global warming potential (GWP) HFCs to lower-GWP blends of HFCs and hydrofluoroolefins (HFOs), and non-F-Gas alternatives, such as propane. CIBSE Journal CPD Module 99, from 2016, noted that propanes operating pressures and temperatures are well suited to use in air conditioning equipment, including chillers, and the natural refrigerant has a GWP of just 3. The latent heat of vaporisation of propane (HC-290) is almost twice that of most common HFC refrigerants, which means a higher cooling/ heating effect for the same refrigerant mass flow2 that requires reduced compressor power and, so, higher operational efficiency. The hydrocarbon propane has good compatibility with materials commonly used in the construction of refrigeration and air conditioning equipment, is commercially available, and relatively inexpensive (at less than 20% of the cost of HFOs2). It can be stored and transported in steel cylinders in the same way as other common refrigerants. However, being flammable and so classified as an A3 class refrigerant there are specific rules to observe. Depending on room volume and application type, there are also limits to the mass of propane that may be used. The LC150 heat pump, developed at Fraunhofer ISE, is based on the climate-friendly refrigerant propane WHAT IS GLOBAL WARMING POTENTIAL? GWP is a measure of how much heat an F-Gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of refrigerant to the amount of heat trapped by a similar mass of carbon dioxide over a 100-year period. In a swiftly changing legislative landscape, the limits vary across the world although, historically, an indoor limit of 150g was, and remains, a common benchmark for a propane charge in single appliances. BS IEC 60335-2-40:2022 ED73 is pending an agreed update, which includes changes that allow higher charge limits for propane of up to 988g in a standard system (with added safety measures) this is likely to eventually shift the global acceptance of higher propane charges. Since the CPD article of 2016, there has been a flurry of activity from national and multinational manufacturers to develop propane-based heat pumps for commercial and domestic applications. The Fraunhofer Institute for Solar Energy Systems (ISE), in Germany, and a consortium of heat pump manufacturers are developing a standardised and refrigerant-reduced propane refrigeration circuit under the low charge 150g LC150 project, as a pathway to developing safe and efficient domestic and small commercial propane-charged heat pumps. Since October 2021, the Fraunhofer ISE project team has been building prototypes for brine heat pumps (systems specifically designed to transfer heat from the ground or surface water to a waterbased heating system), and assembling the individual components www.cibsejournal.com February 2023 53