FI20215909A1 - Refrigeration unit using outdoor air for refrigeration, and refrigeration unit arrangement - Google Patents

Abstract

The object of this description is an ecological cooling device cooled by outdoor air. The energy consumption of the refrigerator can be reduced by utilizing the cold outside air to keep the storage space (22) of the refrigerator at the desired temperature. It can be realized by circulating cold outdoor air in the air space between the interior of the refrigerator and the insulation in the outer shell (21) so that it cools the interior of the cabinet (22). The operation of the device can be controlled intelligently with the help of sensors that detect the temperature, so that the air circulation starts and stops automatically according to what is most appropriate in terms of the refrigeration device and its energy use.

Description

An ecological refrigerator cooled by outside air

Field of invention

The invention is related to refrigeration equipment, and especially to energy-efficient refrigeration equipment.

Background

Refrigeration devices, such as refrigerators, can significantly improve the shelf life of perishable products. Nowadays, the refrigerator is a standard equipment in homes and e.g.

In Europe and North America it is in almost every home. In addition, there are refrigerators in workplaces and in institutions and other private and public spaces where meals are served. Refrigeration appliances are a very significant group of appliances in terms of energy consumption, which is why by improving their energy efficiency, significant energy savings can be achieved both on an individual and societal level.

Quick description

The device according to the invention is characterized by what is presented in the independent patent claims.

The energy consumption of the refrigerator can be reduced by utilizing the cold outside air to keep the storage space of the refrigerator at the desired temperature. It can be implemented by circulating cold outside air in the air space between the interior of the refrigerator and the insulation in the outer shell so that it cools the interior of the cabinet. The operation of the device can be controlled intelligently with the help of sensors that detect the temperature so that the air circulation starts and stops automatically according to what is intended

N 25 — the most suitable in terms of the refrigerator and its energy use. In regions with a cool climate

A significant energy savings can be achieved by utilizing the outside air. For example- ? kikis throughout Finland, the cold can be used to cool the refrigerator 2 for at least 6 months of the year, and in northern Finland even longer. Winters are cold in many southern and some regions and there are also areas, e.g. in the mountains, where the

S 30 — even the nights are cold.

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The outdoor temperature is lowest in winter and at night, when it is both cold and dark. In the warm seasons, when the outside air is too warm to cool the refrigerator, there is a lot of light, thanks to which ecological solar energy can be used to cool the refrigerator.

In severe frosts, the refrigerator can operate completely without external energy. Society's total energy need is at its greatest during the freezing seasons due to the energy required for heating, and to produce it, all (including less environmentally friendly) production methods have to be used. The energy consumption peak can be reduced if the refrigeration equipment does not need electricity at all, or only very little in the cold.

The cooling device according to the invention can be used all over the world in areas where the outside temperature drops below the refrigerator temperature for a significant period of the year. It can also be used in areas where the nights are cold, even if the daytime temperatures are high.

Image list

In the following, the invention is explained in detail with reference to the accompanying drawings, in which:

Figures 1a and 1b show an embodiment of the refrigerating device according to this description, Figure 2 shows another embodiment of the refrigerating device according to this description, and

O figure 3 shows yet another application form of the 3 cooling device according to this description. ™ = a o 30 — Detailed description 3 This description describes an energy-efficient refrigeration device and a method thereof

S to adjust. The refrigerator has a storage space arranged inside the thermally insulated outer shell for cold storage of the products and a refrigerating machine to lower the temperature of the storage space to the temperature range determined by the minimum temperature and maximum temperature.

The thermally insulated outer shell refers to the whole formed by the thermally insulated walls surrounding the storage space. The desired storage temperature depends on the intended use of the refrigerator. A cold appliance can be, for example, a refrigerator or other storage space equipped with refrigeration equipment, such as a wine cabinet or a cool cabinet. In the case of a refrigerator — the desired storage temperature range can be, for example, +2 °C — +6 °C. In order to improve energy efficiency, an air space is arranged in the outer shell of the refrigerator between the storage space and the thermally insulated outer shell.

Air space is the space or air ducts surrounding the storage space at least partially. Figures 1a and 1b show an application form of such a refrigerator.

Figure 1a shows a simplified cross-sectional diagram of the refrigerating device 10 viewed from the front. The cooling device 10 can be, for example, a refrigerator. Figure 1b shows the same cooling device 10 as shown from the side. In Figures 1a and 1b, there is a storage space 12 arranged inside the outer shell 11 comprising thermal insulation 11.1. In Figure 1b showing the side view, a refrigerating machine 17 arranged to cool the storage space is also shown.

The storage area is surrounded by air space 11.2. The air space 11.2 is placed between the storage space 12 and the heat separation 11.1 of the outer shell. The wall 12.1 between the air space 11.2 and the storage space 12 is preferably made of a material that conducts heat well, such as aluminum. In this way, it can be ensured that heat is transferred well between the storage space 12 and the air space 11.2. At the same time, because the thermal insulation 11.1 of the shell 11 is between the air space 11.2 and the air outside the shell 11 (such as room air), the air outside the shell 11 does not significantly heat the air in the air space 11.2. The wall between the storage space 12 and the air space 11.2 can also be formed in such a way that it functions as a heat accumulator. A sufficiently thick wall can, for example, act as a spare cooling plate. Alternately _ 25 — optionally or in addition, separate heat accumulators can be arranged in the refrigerator,

O like heatsinks. The heat accumulators can be cooled, for example, during cold nights, when they help to cool the storage space 12 at other times of the day. = The air space in the shell of the refrigerator according to this description is

I combined intake and exhaust air pipe to arrange the air circulation path in the air space. Fig. > 30 — in sections la and 1b, the intake air pipe 13 is in the lower part of the cooling device 10 and the exhaust air pipe 14

S at the top. The air flow in the air circulation path is shown in figures 1a and 1b with arrows. Cold 5 or cool outdoor air is absorbed into the inlet air pipe 13 and continues from there into the air space 11.2. Air-

In N lasa 11.2, cold or cool air cools the storage space 12 via the wall 12.1 and then continues heated through the air space 11.2 to the exhaust air pipe 14. The heated air exits the exhaust air pipe 14 to the outside air.

The refrigerator also has measuring instruments for measuring the outside temperature, the temperature of the air space organized in the shell and the temperature of the storage space. The measuring devices can be, for example, in the form of temperature sensors. There are preferably at least three sensors, as for example shown in figures 1a and 1b. The first sensor 15.1 can be outside the building or in the supply air pipe 13 as close as possible to the outer wall, where it detects the outdoor air temperature. The second sensor 15.2 can be in the air space of the refrigerator, where it detects the temperature of the air space 11.2. The third sensor 15.3 can be inside the refrigerating device — where it detects the temperature of the interior space 12 of the refrigerating device.

In order to adjust the air circulation in the air space, the cooling device according to this description still has air flow control means arranged in connection with the inlet and/or outlet air pipe. These adjustment means can be implemented in many ways. They can be, for example, a valve or a closing mechanism in the form of a valve. A simple example of a shutter mechanism is a flap operated by an electric motor, which can be set to two different positions (closed and open). In Figures 1a and 1b, such flaps 16.1 and 16.2 function as adjustment means.

The refrigerator also has control means adapted to control the refrigeration machine and air flow control means in response to the measured temperatures. The outside air is circulated in the space between the inside of the refrigerator and the insulated outer shell, so that the air circulation in the intermediate space can be automatically adjusted according to the outside temperature, the temperature of the air in the refrigerator, and the inside temperature. The control means can be, for example, in the form of an electronic control unit. The control unit can have a computing unit (such as a processor, microcontroller or programmable logic) and memory. A program can be stored in the memory that programs the calculation unit to control the refrigeration equipment and

O air flow control devices. The control unit can be programmed to receive s measurement data from measuring instruments and decide based on how the refrigeration equipment = and air flow are used for cooling. Alternatives are the cooling of the refrigerator

I only with the help of an externally conducted air flow, only with the help of the refrigerator's own refrigeration > 30 — or a combination of these. If the temperature inside the refrigerating device falls below the lower limit of the 2 desired temperature range, the cooling of the refrigerating device is stopped completely,

N until cooling is deemed necessary again.

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With the help of temperature sensors, the cooling device is intelligently controlled so that the air is recirculated when air recirculation is useful for cooling the interior. As a general rule, the air is circulated when the outside air temperature is lower than the air space temperature. Air circulation is stopped when the outside air temperature rises so 5 — high that air circulation is no longer beneficial in cooling the refrigerator.

In one form of application, the control means of the refrigerating device are adapted to control the refrigerating machine and the air flow control means in such a way that the temperature of the storage space is primarily cooled by the air flow. When the outside air is too warm to keep the refrigerator in the desired temperature range, the refrigerator is used. The refrigerator can — also be adjusted to use both air flow and refrigeration equipment at the same time.

This is appropriate, for example, when the refrigerator has just been filled with warm food and the temperature of the refrigerator's storage space has risen above the maximum temperature of the desired temperature range. In this case, it is important to cool the interior to the desired temperature as quickly as possible.

When the outside air temperature rises so high that the air circulation is no longer useful, the air circulation stops automatically and the air circulation openings close tightly. The completely tight air space insulates heat well, thus improving the thermal economy of the refrigerator.

In the refrigerator, the desired minimum temperature of the storage space is usually around +2 °C and it is important that the temperature does not drop too low, causing freezing. When the outside air is very cold, the programmed cooling device prevents the indoor space from getting too cold by automatically stopping the air circulation when the temperature drops to the lower limit of the desired temperature range. In this case, no cooling method is used until the temperature of the storage space has risen above the minimum temperature of the temperature range, when - 25 — the air circulation starts again.

O Air circulation can be arranged in different ways. In one form of application, gravitational air circulation is used. Gravity air circulation can be the easiest = arrange when the cooling device is placed against the outer wall of the building. Air

I is made to move by gravity when outside air is brought into the lower part of the refrigerator > 30 and the air outlet can be arranged in the upper part of the refrigerator. Air circulates vertically,

S because warmed air rises upwards. Air moves by gravity when air = comes from below and leaves from above and the air inlet and outlet are far enough apart

N taan and horizontal strokes are short. The refrigerator can also be equipped with a fan that enhances gravity ventilation. The cooling device's control means can be specified to identify when it is worth assisting the gravitational air circulation with a fan. The fan can be low-powered, with a nominal power of less than 2 W, for example. The example in Figures 1a and 1b represents an application form based on gravity-driven air circulation. The supply air pipe 13 is in the lower part of the refrigerating device 10 and the exhaust air pipe 14 is on the top of the refrigerating device 10. Figure 1b shows that the cooling device 10 is placed in the immediate vicinity of the wall 18.

If the cooling device is far from the outer wall, it can be challenging to achieve gravity-driven air circulation. In this case, the cooling device can include a fan that drives the majority of the air flow or the air flow in its entirety. In this type of application, the refrigerator cannot function completely without electricity, but the electricity required by the fan is very little. When the air flow is produced by a fan, the inlet and outlet air ducts do not necessarily need to be placed separately, but they can be close to each other, which means that the ducts can be run in parallel or on top of each other in the interior. Figure 3 — shows a schematic front view of such an application form.

Air circulation can also be implemented using the building's ventilation system. In some applications of the cooling device, the exhaust air pipe of the cooling device can, for example, be adapted to be connected to the exhaust air duct of the building's ventilation system. Ventilation can be gravity-fed, equipped with mechanical exhaust ventilation or it can be fully mechanical. In gravity exhaust air exchange, the exhaust air duct pulls air out most strongly when the outside air is clearly colder than the inside air. The exhaust air duct therefore draws the best when the outside air can be used to cool the refrigerator. In gravity exhaust ventilation, the air circulation can be enhanced if necessary with a low-power blower.

O In buildings with mechanical exhaust ventilation or fully mechanical ventilation, the air circulation is made to work with the help of the negative pressure = produced by the machine, and a separate fan is not necessarily needed in connection with the cabinet.

Figure 2 shows an example of such an application form. Figure 2 shows a side view of the refrigerator 20 placed next to the outer wall 28. Figures 1a and 1b

In the S way, the air is brought along the inlet air pipe 23 from the outside to the lower part of the cabinet 20. Unlike figures 1a 5 and 2b, in figure 2, however, an exhaust air duct is led away from the top of the cabinet

Only 24.1. When the exhaust ventilation works mechanically, the air circulation of the cooling device can be made to work with the help of the negative pressure produced by the exhaust ventilation, without the need for a fan in connection with the cooling device.

When the cooling device is used in connection with mechanical ventilation, it is advantageous to keep the volume of the air space relatively small, so that the device can be cooled efficiently even with a small amount of air. In this case, the variation in recirculation does not really affect the rest of the indoor air exchange or heat recovery.

When the cooling device is a refrigerator, its horizontal dimensions are generally somewhat more than 500 x 500 mm. When the insulation of the shell is subtracted from the external dimensions, the horizontal dimensions of the air space are then less than 500 x 500 mm. If the air is brought from the outside into the lower part of the cabinet with a pipe with a diameter of 80 mm into an air space 100 mm high, is the volume of the air space in the lower part of the cabinet about 25 dm? and the height of the lower part can still be lowered in part of the space, in which case its volume can be estimated at about 15 dm3. At the edges of the refrigerator, the thickness of the air space can be, for example, about 10 mm, in which case the air space at the edges is — depending on the size of the cabinet, a total of 10-20 dm?. In the upper part of the cabinet, the suitable height of the air space can be about 20 mm, so the volume of the air space there is about 5 dm3. The total volume of the air space of the tall refrigerator is thus about 40 dm?. If the air volume is, for example, 0.8 dm?/s, which means 2880 dm?/h, the air volume is enough to change the air in the entire air space of a large refrigerator more than 60 times per hour, i.e. more than once per minute.

In Figure 3, the refrigeration device 30, which can be, for example, a refrigerator, comprises a storage space 32 and an outer shell 31 surrounding it. The outer shell includes thermal insulation 31.1 and an air space 31.2. The storage space 32 and the air space 31.2 are separated by the storage space-defining case formed by the walls 32.1. The walls 32.1 are made of heat-conducting material. An inlet air pipe 33 and an exhaust air pipe 34 are connected to the air space 31.2. Pipes

O 33 and 34 are next to each other in the upper part of the refrigerating device 30. The exhaust air pipe 34 has a fan s 34.1. The air space 31.2 is divided by a partition 31.3 in such a way that through the inlet air pipe 33 = the incoming air has to circulate around the storage space 32 to reach the exhaust air pipe

I keen 34. In this way, cool air is obtained to cool the air space 32. The refrigerator 30 has > 30 — like the previously presented application forms — several temperature sensors. first-

The sensor 35.1 can be outside or in the inlet air pipe 33, the second sensor 35.2 is in the air space 31.2 and the third sensor 35.3 is in the storage space 32. The control means of the refrigerator are

N is adapted to control the air flow control devices 36.1 and 36.2 of the refrigerating device and the refrigerating machinery on the basis of the temperature data provided by the measuring sensors 35.1, 35.2 and 35.3, for example in the same way as shown earlier in this description.

The cooling device according to this description can be implemented in many ways, and the implementation methods are not limited to the examples presented above.

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Claims (6)

Patent Claims 1. A refrigerator with - — a storage space arranged inside a thermally insulated outer shell for cold storage of products, and - — a refrigerating machine for lowering the temperature of the storage space to the desired temperature range defined by the minimum temperature and maximum temperature, characterized by the fact that the refrigerator also comprises - — an air space arranged in the outer shell, - — connected to the air space to organize the air circulation path of the inlet and outlet air pipe into the air space, - — measuring devices for measuring the outside temperature, the air space inside the shell and the temperatures of the storage space, - air flow control devices arranged in connection with the inlet and/or outlet air pipe to regulate the air circulation of the air space, and - — control devices adapted to control the refrigeration equipment and air flow control devices in response to the measured temperatures. 2. Refrigeration device according to claim 1, in which the control means are adapted to divide the refrigeration machinery and the air flow control means so that & s - — the temperature of the storage space is regulated primarily by means of the air flow 5 when the outside temperature cools the temperature of the air space and the temperature of the storage space I remains below the desired maximum temperature, a S - — the temperature of the storage space is primarily adjusted with the help of refrigeration equipment 0 25 when the outside air is not cold enough to keep the temperature of the storage space below the desired maximum temperature and - when the temperature of the storage space drops to the lower limit of the minimum temperature of the desired temperature range, neither the refrigeration equipment nor the air flow are used. 3. Refrigeration device according to claim 1 or 2, where - — the refrigeration device additionally comprises a fan to create air circulation in the air space. 4. A cooling device according to claim 1 or 2, where - the inlet air pipe is placed in the lower part of the cooling device and the exhaust air pipe is placed in the upper part of the cooling device to enable gravitational air circulation in the air space. 5. A cooling device according to one of claim 4, where - — the exhaust air pipe is adapted to be connected to the exhaust air duct of the building's ventilation system. 6. A cooling device according to claim 4, where - — the cooling device comprises a fan adapted to assist gravity N air circulation in the air space, and N 2 20 - — the control means are adapted to assist gravity air circulation 5 with a fan, when air circulation cools the hot room of the air space of the cabinet, but gravity air circulation does not enough to maintain air circulation sufficient for cooling + in air space S o LO N N 25