Conference Year

2016

Keywords

low GWP refrigerant, class 2L flammable, burning velocity

Abstract

The demand for environmentally sustainable substances is high. The number of low global warming (GWP) refrigerants entering the market is rapidly increasing to meet environmental needs. Many of the new low GWP refrigerants are mildly flammable or 2L as classified by ISO 817 and ANSI/ASHRAE Standard 34(ASHRAE 2008, ISO 2014). The new refrigerant flammability class provides the heating/air-conditioning/refrigeration industry more options to meet environmental regulations with equipment designed for low flammability. Mildly flammable refrigerants are defined as refrigerants which have burning velocity (BV) less than 10 cm/sec and heat of combustion (HOC) less than 19,000 kJ/kg. A relatively unexplored potential ignition source is a hot surface which can be found in air conditioning auxiliary heaters and other refrigeration systems. Maximum hot surface temperatures are also specified in several equipment standards.  Recently, work was conducted to review potential ignition/non-ignition for ten different 2L refrigerants which were released onto a hot surface. Tests were designed to simulate a 2L refrigerant leak onto an 850C hot surface within a piece of equipment or within ductwork.   In particular, individual refrigerants were released onto a round heated metal surface and potential ignition was observed for a set time period after the refrigerant was released. This work summarizes results from two different flat plate test configurations used to evaluate potential ignition. A range of parameters were tested and noted during the testing, along with pros and cons of the different tests and how these tests relate to potential œreal-world ignition sources.

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