JPS621676Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a cooling box with a transparent plate provided in the opening, and its purpose is to prevent the inside of the refrigerator from being seen through even if the cooling box is installed in a place that receives direct sunlight. To prevent dew condensation on a transparent plate without damaging it and to maintain a predetermined internal temperature.

In general, cooling boxes such as refrigerated cases that have openings on the top surface for storing and taking out products are placed between two transparent glasses in the top opening to insulate the inside and outside of the refrigerator and to maintain the transparency of the inside of the refrigerator. It had a transparent door filled with air that could be opened and closed. This transparent door was an attempt to reduce heat transfer by conduction by taking advantage of the low thermal conductivity of dry air, which forms a static air layer. The spectral characteristics of glass have a high emissivity in the room temperature range, so most of the radiant heat from outside the refrigerator is absorbed by the glass outside the refrigerator and re-radiated from the glass inside the refrigerator via dry air into the interior of the refrigerator. They had become equivalent. Therefore, when using this type of transparent door, even if heat transfer by conduction is prevented, there is no insulating effect against radiant heat transfer.

Furthermore, since the glass itself has a high emissivity, the glass inside the refrigerator is radiatively cooled by the low temperature inside the refrigerator, and the glass outside the refrigerator is also radiatively cooled through the dry air. There was a problem that condensation formed on the back surface and the surface of the outside glass.

In order to prevent this condensation, an electric heater was built into the transparent door to heat the glass. However, the cost of transparent doors increases and the drawbacks are the risk of electrical leakage and increased refrigeration load. It occurred in

Furthermore, Japanese Patent Application Laid-open No. 52-61345 states, ``The device is arranged so that it can be seen between the low-temperature region and the warm region, and has at least first and second glass plates, and the outer surface of the first glass plate is used. a second glass plate facing and spaced from an unexposed surface of the first glass plate, the second glass plate having an electrical heating means attached to the first glass plate; In the insulating multiple glass plate window structure in which the second glass plate is provided with a substantially transparent infrared radiation coating.'' In this configuration, since an infrared reflective coating is provided on the surface of the second glass plate facing the warm region, the temperature of the second glass plate falls below the dew point due to radiation cooling of the cold air in the low temperature region, preventing dew condensation or frost formation. This resulted in disadvantageous defects and the perspective effect was impaired.

This proposal was made in view of the above drawbacks, and an example thereof will be explained below with reference to FIGS. 1 and 2.
is a cooling box body such as a refrigerated case, whose main body is made up of an insulating wall 2 with an opening 3 for storing and taking out products on the top surface, and an inner box 2a forming the inner wall of the insulating wall. The load (products) in the refrigerator interior 4 is cooled by cooling air that is heat exchanged in a cooler 5 disposed on the outer surface of the inner box and causes natural convection. Reference numeral 6 denotes a load line (loading waterline) provided in the inner box 2a, and the load is stored and cooled below the line. Reference numeral 7 denotes a transparent door provided in the upper surface opening that shows whether it can be opened or closed, and includes a main body plate 8 made of transparent glass or resin;
a membrane 9 affixed to the back surface of the plate, that is, the inner side surface of the refrigerator;
It is composed of the plate body and a protective member 10 with a handle 11 that covers the periphery of the membrane. Reference numeral 12 denotes an air layer formed between the transparent door 7 and the load line 6 by providing the transparent door at the top opening 3, and this air layer is at rest because its temperature is higher than the air layer below the load line 6. state. The film is, for example, a vapor-deposited film using a metal with high emissivity in the infrared region, and has a selective transmission/reflection ability, transmits visible light,
It reflects infrared rays.

According to such a configuration, the air layer 12 formed between the transparent door 7 and the load line 6 when the door is closed has a higher temperature than the cooling air layer below the load line 6, and is maintained in a substantially stationary state. Therefore, the film 9 acts as a boundary layer to prevent natural convection cooling air from coming into contact with the transparent door 7, and to alleviate radiation cooling from the cooling air to the transparent door 7. At the same time, the film 9 itself acts as a boundary layer in the infrared region. Because the reflectance is high, the temperature of the heat transfer surface is low, and the radiation cooling from the cooling air is reflected in four directions inside the refrigerator, the heat transfer from the inside 4 to the membrane 9 is so small that it can be ignored. The temperature of the inside side of the transparent door 7 can be maintained above the dew point of the inside 4 of the refrigerator. Moreover, since the plate body 8 itself has a large emissivity in the infrared region,
In addition to absorbing radiant heat (infrared rays) from outside the refrigerator, since the film 9 itself has a low emissivity, the plate 8
The inside surface of the plate body 8 reflects the infrared rays that have passed through the refrigerator toward the outside of the refrigerator, and the temperature of not only the outside surface of the plate body 8 but also the temperature of the outside surface of the refrigerator is controlled by the air surrounding the cooling box body 1. (outside air) temperature,
Can be maintained above the dew point. As a result, dew condensation on the front and back surfaces of the transparent door 7 can be prevented, and the see-through effect in the visible light range can be improved.

Figure 3 shows the transparent door A of the present invention and the conventional transparent door B made of double-glazed glass installed in the cooling box 1, and the surface (outside the refrigerator) temperature a and the back surface (inside the refrigerator) temperature b of each door.
It is a characteristic diagram comparing the temperature c on the load line and the temperature c on the load line in each box body under various conditions. Note that d is the outside temperature. According to Figure 3, door A always has a higher surface temperature than door B under various conditions;
The load line temperature of the box with door B is lower than that of the box with door B, and the box with door A has a larger temperature difference between the surface temperature and the load line temperature than the box with door B, which has a greater insulation effect. It turns out that it is excellent.
In addition, door A is always maintained at a temperature closer to the outside air temperature than door B, and in the sun where it receives direct sunlight, the plate 8 itself absorbs radiant heat directly from outside the refrigerator and indirectly absorbs radiant heat due to reflection from the membrane 9. It can be seen that the temperature is higher than the outside temperature and is always maintained above the dew point temperature, and the temperature inside the refrigerator is lower in the box with door A than in the box with door B. Therefore, the cooling box body 1 of the present invention can be fully used under direct sunlight and can maintain a predetermined internal temperature.

As described above, the present invention provides a selective transmission reflection film on the internal side of the transparent plate provided in the opening, which maintains the temperature of the external and internal sides of the plate higher than the outside air temperature in sunlight. Because it is,
The film absorbs the heat from the direct sunlight that the plate itself receives from outside the refrigerator, and the indirect radiant heat absorption that occurs when the film reflects the direct sunlight that has passed through the plate to the outside of the refrigerator. By reflecting the radiation cooling of the cold air inside the refrigerator to the inside of the refrigerator, it is possible to maintain the plate itself at a temperature higher than the outside air temperature, that is, above the dew point, and prevent condensation or frost from forming on both the front and back surfaces of the plate. The inside temperature can be maintained at a predetermined temperature by preventing loss of internal temperature by reflecting radiation cooling.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view of the cooling box of the present invention, FIG. 2 is a perspective view of the transparent door, and FIG. 3 is a temperature characteristic diagram of the cooling box of the present invention and the conventional box. 3...opening, 8...plate, 9...membrane.

Claims (1)

[Scope of utility model registration request] A transparent plate with a high emissivity in the infrared range is provided in the opening, and a selective transmission reflector is installed on the inside side of the plate to have a high reflectance in the infrared range and reflect radiation cooling from the cooling air toward the interior of the refrigerator. A cooling box characterized in that a membrane is provided so that when exposed to direct sunlight, the plate body itself absorbs radiant heat from outside the refrigerator and absorbs indirect radiant heat due to reflection of the membrane, so that the temperature becomes higher than the outside air temperature. body.