The present research focuses on increasing the understanding of compressor off-design operation and its impact on the performance of a refrigerator/freezer. For this purpose, a refrigerator with a given compressor was tested at the 90degF (32.2degC) standard and at 60degF (15.6degC) and 110degF (43.3degC) off-design ambient temperatures in an environmental chamber. Later, the compressor was separately tested on a calorimeter at the same ambient conditions, and its nine-point map was developed at a 90degF (32.2deg) standard test condition, and four-point maps were developed at 60degF (15.6degC) and 110degF (43.3degC) off-design conditions. The performance of the refrigerator was simulated by the US Environmental Protection Agency’s (EPA) Refrigerator Analysis (ERA) software complemented by the measured compressor maps and the refrigerator hardware information. ERA predicted the experimentally measured power consumption at 90degF (32.2degC) ambient temperature within 1.0% to 8.3%. It was also found that under off-design conditions, the accuracy of prediction was improved by using the newly developed compressor map. Presently the model uses a fixed value for the thermal conductivity, independent of the ambient and cabinet temperatures. When an actual temperature-dependent expression is used for the conductivity, the agreement between the predicted and measured energy consumption improves. At 60degF (15.6degC), the difference between the predicted and measured values is 8.5% when temperature dependence is accounted for vs. 11.2% difference when it is not. Similarly, at 90degF (32.2degC), the difference is 2.9% vs. 4.5% and at 110degF (43.3degC), the difference is 6.3% vs. 7.2%.
KEYWORDS: year 1997, Computer programs, compressors, calculating, performance, measuring, thermal conductivity, comparing, refrigerators, freezers, testing, evaporators, energy consumption, thermal resistance
Citation: Symposium, ASHRAE Trans. 1997, vol.103, part 1
Product Details
- Published:
- 1997
- File Size:
- 1 file , 1.3 MB
- Product Code(s):
- D-16452
