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Window air conditioners (WAC) are cheap and sold in large numbers internationally as alternatives to central air-conditioning systems. There are nearly 57 million WACs currently operating within United States alone which account for approximately 1.5% of the total US residential energy use or about 0.21 quads per year. Due to global warming and other environmental concerns, there is a need to find an alternative to the currently used refrigerant R410a in WACs. There are several alternative refrigerant options available, including R32, R600a, R290 and R1234yf, but most of these are slightly flammable. Due to the compact size configuration and small refrigerant charge in a WAC, however, the flammability of the refrigerant is less of a concern. Because of this, these potential refrigerants can be evaluated as an alternative to R410a. This study documents the experimental performance of a WAC unit charged with R410a in a laboratory environment, and its comparison with the same unit charged with higher concentration of R32 (90% molar concentration) in the original mixture of R410a. Based on the test data, a fundamental WAC system model, having detailed segment-by-segment heat exchanger models was developed and calibrated. This calibrated model was then used to perform parametrics to assess the performance of the WAC with alternative refrigerants including R134a, R32, R600a, R290, R1234yf and R1234ze. The paper discusses the associated effects of each refrigerant on the system efficiency, component sizing, compressor discharge temperature etc, and thier suitability for window air conditioners. |
