Safety with flammable refrigerants - presentation of IEA HPT Annex 64

With the new F-gas directive in Europe, and with the realization of the possible negative effects of synthetic refrigerants, there is an increased interest for natural refrigerants. Hydrocarbons, and in particular R-290, is expected to take over a large share of many of the market segments for Heat Pumps and refrigeration equipment in the near future. While hydrocarbons are excellent refrigerants from thermodynamic point of view, they have the obvious drawback of being flammable. As the industry has been used to using non-flammable refrigerants during the last 90 years, it is now necessary to adopt and learn to handle flammable refrigerants safely, both during production, installation, servicing and decommissioning.

Within the IEA HPT Annex 64 researchers from several countries are cooperating to identify and evaluate risks, develop components and systems for a minimum charge of refrigerant and investigating methods of identifying leakages. The ultimate goal of the Annex is to be able to contribute with basic knowledge which can be used in formulating updated standards for heat pumps, refrigeration equipment and other types of equipment which have traditionally been using synthetic refrigerants to allow safe use of hydrocarbons. In this seminar we will present some of the ongoing work within the annex in some short presentations from different members of the team, coming from different countries. The presentations will include numerical simulations of leakages, examples of system designs with low charge and examples of how components can be designed to be efficient with small internal volume. Different methods of fulfilling the standards when installing a Heat Pump with R-290 inside a building will also be discussed. Numerical simulations have shown the importance of stirring the room air with a fan in case of a leakage to avoid flammable concentrations to be reached.