In general, refrigerator vehicles are used to carry loads such as food products that may lose freshness thereof depending upon temperature.
Refrigerator vehicles for carrying various types of frozen or low-temperature foods/goods that cannot be stored or carried at room temperature may be classified into small straight trucks and medium and large semi-trailers according to a type and load capacity thereof. It should be understood that, terms, such as refrigerator vehicles, refrigeration trailers and refrigerators, as used herein, do not mean only refrigerating functions excluding freezing functions, and comprehensively include terms such as freezer vehicles, freezing trailers, and freezers.
As shown in FIG. 1, a refrigerator vehicle is provided at a loading station thereof with a refrigeration trailer 20 having an enclosure shape, and a refrigerator 21 is provided at a head side of the refrigerator vehicle or at one upper side of the refrigeration trailer 20. The inner space of the refrigeration trailer 20 is maintained at a low temperature by an evaporator of the refrigerator 21. The refrigerator 21 is usually an engine driven refrigerator that is driven by a main engine or sub-engine of the refrigerator vehicle.
In a refrigeration cycle of the refrigerator 21, a refrigerant circulates via circulation pipes in order of compressor, condenser, expander, and evaporator.
Operation of the refrigerator 21 is as follows: the compressor is driven by power of a sub-engine provided at the refrigeration trailer 20, a high-temperature, low-pressure refrigerant is changed into a medium-temperature, high-pressure refrigerant in the condenser as the compressor is driven, the refrigerant supplied from the condenser passes through the expansion valve and flows into the evaporator, the liquid refrigerant absorbs ambient heat while being instantaneously gasified, and cool air is created around the evaporator and discharged into the refrigeration trailer 20 by a separate exhaust fan.
Through constant repetition of the refrigeration cycle, the inner space of the refrigeration trailer 20 is maintained at a preset low temperature, which makes it possible to stably carry all foods and beverages required to be refrigerated or frozen and low-temperature goods under an optimal temperature condition.
FIG. 2 shows an interior of the refrigeration trailer in the related art.
Cool air supplied by the refrigerator 21 is fed into all spaces in the refrigeration trailer 20 through a duct 30 disposed at an upper portion of the refrigeration trailer 20. The duct 30 is open at some portions of left and right sides thereof and at a distal end thereof. As shown in FIG. 2, some cool air is supplied to loads (L) through the left and right openings, and the rest is supplied through the distal opening to the inner space of the refrigeration trailer 20 and circulates therein.
However, the refrigeration system of the refrigeration trailer 20 supplies cool air into the refrigeration trailer 20 irrespective of quantity and volume of the loads (L) in order to maintain the entire inner space of the refrigeration trailer 20 at a preset temperature, which causes unnecessary energy (heat or fuel) consumption even when the loads (L) are small in quantity and volume.
Although refrigerator vehicle have an intake weight determined according to classes thereof, the refrigerator vehicle inevitably have a loading space left in a refrigeration trailer when carrying loads, such as ice cream, having heavy weight and small volume.
That is, as shown in FIG. 2, even when the refrigeration trailer 20 is not completely filled with loads (L), the entire inner space thereof is maintained at a low temperature, thereby causing high fuel and oil costs and overload of the refrigeration system in long-distance transportation.
In order to solve this problem, attempts have been made to divide an inner space of a refrigeration trailer using fixed partition walls. However, such attempts are inefficient for real-life situations in which loads are always variable in quantity and volume, and cause limitation in quantity of loads and inconvenience of a loading operation.