compartment of 90 litres. The freezer was located on the upper part of the refrigerator
and separated from the fridge compartment by a plastic tray underneath it. The
cold head of the compressor unit is in direct contact with the aluminium case of the
freezer. Cooling takes place primarily in the freezer compartment and the fridge
compartment is cooled by the ‘‘heat leak’’ from the freezer compartment. This is a
simple and effective configuration to obtain two different temperature-zones. However,
it should be noted that this might not be the optimal design if the freezer compartment
is not required. The refrigerator cabinet is identical to those employed by
TER-1 and TER-2.
3. Cooling performance
The cooling performance of a refrigerator is generally specified by the coefficient
of performance, heat-pumping capacity, cooling-down rate (CDR) and temperature
stability. Fig. 3 shows a schematic experimental set-up for measuring the COP of
conventional and thermoelectric refrigerators. An electrical heater was placed in
the refrigerated cabinet to provide a precisely controllable heat-load. The COP of
the refrigerator, g, in such operating conditions can then be expressed by