As any door of HRF is opened, warm and moist air will get into the cabinets, and that thus
would encompass extra thermal load for the refrigeration system. Fig. 4(a) shows the power
consumption variation of fixed frequency HRF A for food compartment door opening test at
ambient temperature of 15 C. From the test result, the door opening increased total energy
consumption by 4.12% to that of static test. To prevent the thermal penetration from ambient, the
refrigeration system of HRF should increase the running time and thus would consume more
Fig. 4.energy. Besides, the door opening of HRF caused the storage temperature rise inside cabinets,
which should affect the food quality. The maintenance of stable storage temperature for fixed
frequency HRF is generally implemented by using turning on/off of electric relay, that is in series
with power line of AC motor inside compressor. The sharp cycling waveform during frequent
starting and ending for power should arise extra cycling loss as described in Fig. 4(a). The frequent
sharp pulses for compressor always generate noisiness and affect domestic living seriously.