Lean Flammability Limit as a Fundamental Refrigerant Property (Phase 3)

摘要

A program began in October, 1994, to examine the potential for a counter-flowburner to measure accurate flammability limits of refrigerants. In phases I and II of this research (reported earlier), the feasibility of using the counter-flow burner to define the lower flammability limit (LFL) of R-32 (CH2F2) and the critical flammability ratio (CFR) of R-125 (C2HF5)/R-32 mixtures in dry air at room temperature were demonstrated. The objectives for phase III of the study were (1) to determine the sensitivity of the measured LFL to changes in burner design, (2) to modify the burner to operate at elevated temperatures and with liquid refrigerants (R-245ca, or C3H3F5), and (3) to design a simple burner that could be used by industry and other research laboratories for estimating the flammability of new refrigerants. This report reviews the past work done on premixed, counter-flowing flames, describes the current counter-flow burner facility and operating procedures, presents the experimental results with the analysis that yields the above flammability limits, and recommends further activities that could lead to a science-based methodology for assessing the risk of fire from refrigeration machine working fluids.