From test results, the variable frequency HRF B consumed more energy by 0.39% during door
opening test than that of static testing and the fixed frequency HRF A consumed more energy by 4.12% for door opening test. Without door opening, the static test indicated that the variable
frequency HRF B saved more energy than the fixed frequency HRF A by 22.15%. With door
opening test, the variable frequency HRF B saved more energy than the fixed frequency HRF A
by 24.94%.
From Table 1, the variable frequency HRF B has two doors for the freezer cabinet. Only the
door, which affected with more energy consumption, was opened during test. The contact area of
this freezers door, surrounding with ambient moist warm air, was smaller than that of fixed
frequency HRF A by about 50%. When this freezers door of HRF B was open, the thermal
entrance cross the door contact edges of HRF B was also smaller that that of HRF A. From this
point of view, multiple door design can help to reduce the thermal leakage from door edges as well
as the energy consumption due to door opening.