DE102007015388A1 - Refrigerator, especially in a refrigerated vehicle - Google Patents

Abstract

The invention relates to a cooling space with a wall (11) through which gas can flow at least in a partial region with a predetermined thickness (s) and with an inner side (13) and an outer side (12), between which a plurality of channels (9) run. wherein the channels (9) have a substantially greater length (L) than the thickness (s) of the wall (11) and connect the interior (14) of the cooling space to the environment. The ratio of length (L) of the channels (9) to the thickness (s) of the wall (11) is at least 10, preferably the channels are the length of the longer length of the wall. The channels (9) extend between the inside (13) of the wall (11) and outside (12) of the wall (11) at an acute angle (alpha), preferably from 0.1 ° to 10 °, to the inside (13). or the outer side (12) of the wall (11). When cooling the cold room by a liquefied cryogenic glass, especially nitrogen, this gas can be dissipated to the environment after evaporation through the channels (9) while the wall (11), in particular a ceiling area under sunlight, additionally cool. The residual refrigeration contained in the vaporized gas is used effectively and reduces the power required to cool the cold room.

Description

The The invention relates to a refrigerator, in particular a refrigerated container or a refrigerated vehicle with such a refrigerator. Furthermore, the invention relates to a structure for walls of cooled by a cold liquefied gas Cold rooms.

For the cooling of refrigerated vehicles, it is z. B. known Nitrogen in liquid, cryogenic form in a vacuum insulated Carry containers on or in the vehicle. This is taken with a cooling demand via a pipeline and by the autogenous pressure of the medium either directly into a cold room sprayed or passed through a heat exchanger, which the cold in the cold room makes usable and the nitrogen dissipates into the open air. The procedure is particularly simple and insensitive to interference. Furthermore, the cooling capacity regardless of the ambient temperature always the same. It is in principle only through the passage of the spray nozzles limited. Therefore, refrigerated with liquid nitrogen Lorries used in distribution for food be used and naturally frequent Door openings during cooling operation have significant advantages in the quality of cooling. This is especially the case in midsummer when mechanical refrigeration systems with power drops on the capacitors and with icing to fight the evaporators.

there Of course, the cold stored in the gas can not be used fully, because it creates exhaust, the must escape from the refrigerator. This exhaust gas is due to the process always colder than the setpoint temperature of the cold room and thus considerably colder than about the ambient temperatures on midsummer days with a refrigerated vehicle.

Known is a use of the exhaust gas to fan it pneumatically drive. The existing residual cold of the gas is thereby but not used.

The Walls of the refrigerator are insulated to the needs to minimize cooling capacity. A very big one Part of the heat input into the cold room of a truck In midsummer happens by direct sunlight, in particular on the roof surface. For the roof area are therefore a high reflectance coating, a thicker insulation or a shadowing known. Straight on the roof surface In sunshine, a high radiant power acts; the too higher temperatures than the environment. So can the temperature of the roof surface at 35 ° C Outdoor temperature rise to about 60 ° C and the Increase insulation requirements accordingly.

From the DE 202 07 145 is an insulation structure for a refrigerated vehicle known. Above the ceiling and / or on individual walls, a shading shielding system is mounted at a distance. The gap formed by the shielding system is at least partially ventilated to dissipate heat energy, which has collected near the outer surface, by means of the air flowing through.

Also but this is not a use of the residual cold of the exhaust gas when cooled with cryogenic liquid gas reached.

It It is therefore an object of the present invention to provide a refrigerator, especially for a refrigerated vehicle to ask, in which the residual cold exiting exhaust gas can be used effectively, especially for cooling of wall areas that are exposed to strong heat radiation.

These The object is achieved by a refrigerator according to claim 1 and a Refrigerated vehicle solved according to claim 13. advantageous Embodiments and developments, each individually or in can be suitably combined with each other as desired, are specified in the subclaims.

One Cooling space according to the invention has at least one in a partial region of gas-permeable wall with a predetermined thickness and with an inside and an outside between which run a plurality of channels. The channels have a much larger one Length as the thickness of the wall and connect the gas outlet the heat exchanger inside the refrigerator with a manifold on the outside of the refrigerator. Through the channels, gas from the heat exchanger in warmer areas of isolation and finally directed to the outdoor area. On the way through the wall, which preferably follows almost the course of the wall, so this not pierces across, find the channels over the thickness of the wall a temperature profile before, which they go through so that the conducted gas is always colder than the surrounding gas Isolation. When cold exhaust gas flows through, it therefore absorbs heat from the isolation and thus already leads deep into the Isolation sunken heat back to the outside from. If the wall from the outside by heat radiation, For example, heated by sunlight, so will the cold exhaust gas heated in the channels and thereby reduces the cold losses from the interior of the refrigerator through the wall. The cost of isolation can be reduced, or with the same insulation, the energy required for cooling be significantly reduced.

Advantageously, the channels are embedded in an insulation, which preferably consists of foamed material. This allows a easy alignment and fixing of the channels.

The Ratio of length of channels to thickness the wall is included in a preferred embodiment at least 10, preferably at the root of the sum of the squares of thickness and length. Basically, the Channels about the length of the wall piece have them cool. But it is also possible a larger number of channels with smaller ones Provide length. Direction and course of the channels can score from practical and constructive face depend. It is important that the desired Temperature profile over the length of the channels can adjust, so cross-section, number, length and course the channels in relation to typical amounts of exhaust gas is selected appropriately per unit of time.

In a favorable embodiment, the channels between inside of the wall surface and outside the wall surface at an acute angle to the inside the wall surface or the outside of the wall surface guided, in particular at an angle of 0.1 ° to 20 °.

By The angle of inclination can be dependent on the residence time of the cold exhaust gas controlled by the volume and cross section of the channels so that the heating of the exhaust gas according to the temperature profile takes place in the insulation and the exhaust gas always at a certain Value is cooler than the surrounding insulation. The function but also z. B. be achieved by a stepped course.

Advantageous the channels are running.

Of the Temperature profile in a homogeneous insulating material is linear. Straight channels give easy adjustment solely about the angle of inclination to the inside or outside.

In favorable embodiment, the channels by a hollow-chamber double-web plate embedded in the insulation educated. This allows a cost-effective Implementation of the invention while maintaining the stability of Wall.

In In a particularly preferred embodiment, the flowthrough is Wall in the roof area of the refrigerator. Especially in mobile Cold rooms, such as refrigerated containers to achieve the greatest effect in the roof area. This heats up when exposed to sunlight the ambient temperature and leads to additional Heat input into the cold room. But that too Exhaust gas heats up to this higher temperature value can be, this results in a greater impact than on other surfaces.

Advantageous The flow-through wall surface can also be used in the floor area lie. Due to the heat radiation of z. B. by sunlight heated streets can be used in mobile cold stores, such as refrigerated containers, even here increased Heat registration exist, so that here are the benefits the invention can be used. in principle can the invention with all walls with increased Heat input can be used.

The Cooling can be by a direct or indirect in the cold room introduced cryogenic, liquid gas, in particular nitrogen take place, the gas after evaporation from the evaporator in the interior of the refrigerator through the channels to the outside is directed.

Of the Cooling space according to the invention is special advantageous if the cooling liquefied by cryogenic Gases occurs because then sufficient amounts of cold exhaust gas Available during other cooling processes only the amount of replacement air due to the ventilation to Available.

In favorable embodiment is an inventive Refrigerator for transporting goods on a vehicle arranged.

There the advantages of the invention can be used particularly well become. Especially with refrigerated vehicles are the possibilities the isolation of weight and volume reasons limited. On the other hand, just these are a high heat input Exposed to sunlight, z. B. over the roof area and floor space.

A advantageous embodiment and development will be with reference to the following Drawings exemplified.

1 schematically shows a refrigerated vehicle according to the invention and

2 in section schematically the roof area of a erfindungemäßen refrigerator and a temperature diagram.

1 shows a refrigerated vehicle according to the invention 1 in a side view with a cooling space according to the invention and a cooling module 2 that in a roof area 3 on a front side of the refrigerated vehicle 1 is mounted. The cooling module 2 includes a heat exchanger that comes from a thermally insulated tank 4 with liquefied gas, here nitrogen, is supplied. The Tank 4 has a jacket for thermal insulation, preferably a vacuum jacket or a foam jacket and is in communication with the Kühlmo dul 2 , The tank is in a floor area 5 of the refrigerated vehicle 2 attached.

2 shows a wall 11 with an outside 12 and an inside 13 in the roof area 3 a cooling chamber, not shown in cross section. The wall 11 is executed in the present embodiment as a hollow chamber roof with hollow chambers, wherein the hollow chambers by a double web plate 6 are formed at an angle α to the inside 13 or outside 12 the Wall 11 in an insulation 7 is foamed, and s the thick wall 11 from the inside 13 indicates. Through a distribution channel 8th will be cold exhaust gas from the inside 14 the cooling space individual channels formed by the hollow chambers 9 supplied and flows through these as indicated by an arrow. Through a collection channel 10 The heated exhaust gas is collected and discharged into the environment. The channels 9 have a length L that is much larger than the thickness s of the wall 11 , They therefore run with little inclination to the wall 11 ,

In a temperature diagram, in addition to the cross-sectional representation, the temperature t of the exhaust gas in the channels 9 plotted over the distance s.

The exhaust gas is in the channels 9 first led close to the inside, since the exhaust gas is still colder than the internal temperature of the cooling room. The gas flow follows the temperature profile in the roof. The gas stream is typically slightly colder than the surrounding insulation 7 so that he can escape this heat, which is a cooling of the still remaining outside insulation 7 equivalent.

Instead of continuously in channels 9 The exhaust gas can also be led outwards in 3-5 steps.

In a cold room with an insulation value Kw of 0.4 W / m ² K, a total surface area of approximately 92 m ² and a roof area of 20 m ² , the incidence of heat H by heat transfer, without taking into account the heat radiation and without the roof surface of outside to inside at an internal temperature of -20 ° C and an ambient temperature of 35 ° C and thus a temperature difference of 55 K: H = 0.4 W / m 2 K · 72 m 2 · 55 K = 1584 W

The heat radiation S on the roof surface at a reflectance of 80% and an angle of incidence of 45 ° to the vertical is: S = 0.2 x 20 m 2 · 1 kW / m 2 · Cos (45 °) = 2000 W

Due to this high heating power, the surface of the roof heats up significantly above the ambient temperature. The temperature of the roof surface can rise to approx. 60 ° C. As a result, the roof gives off a large part of its heat again. Nevertheless, it must be assumed that a roof heat input D results from this surface temperature: D = 0.4 W / m 2 K · 20 m 2 · 80 K = 640 W

The total heat input into the cold room is thus approximately H + D = 2400 W. In the present example, the exhaust gas temperature is -30 ° C. It can be heated in the roof to + 40 ° C. This 70 K means a quantity of heat A, which is dissipated by the exhaust gas. A = 70 K × 35 kg / h × 1 kJ / kg ° C = 2450 kJ / h = 680 W

The means that the heat entering through the roof 100% can be dissipated, without additional To spend energy. The resulting energy savings is (640/2400 =) 27%.

something similar applies to the floor area. Here is the heat radiation of the strongly heated road asphalt. The natural heat transfer by convection fails, because the heat accumulates under the vehicle body.

1

Reefer Truck

2

cooling module

3

roof

4

tank

5

floor area

6

Double-wall sheet

7

insulation

8th

distribution channel

9

channel

10

collecting duct

11

wall

12

outside

13

inside

14

Interior of the refrigerator

s

thickness

t

temperature

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 20207145 [0006]

Claims (13)

Cooling chamber with a wall through which gas can flow, at least in a partial region ( 11 ) with a predetermined thickness (s) and with an inside ( 13 ) and an outside ( 12 ), between which a plurality of channels ( 9 ), characterized in that the channels ( 9 ) have a substantially greater length (L) than the thickness (s) of the wall ( 11 ) and the interior ( 14 ) of the refrigerator with the environment. Refrigerator according to claim 1, characterized in that the course and the total cross-sectional area of the channels ( 9 ) in the wall ( 11 ) is such that a gas flowing through it at each point is colder than the temperature of the wall at the respective point. Refrigerator according to claim 1 or 2, characterized in that the channels ( 9 ) in an insulation ( 7 ), preferably of foamed material, are embedded. Refrigerator according to claim 1, 2 or 3, characterized in that the ratio of length (L) of the channels ( 9 ) to the thickness (s) of the wall ( 11 ) is at least 10. Refrigerator according to claim 1, 2 or 3, characterized in that the length of the channels ( 9 ) about the greatest length of the flowed through portion of the wall ( 11 ) is. Refrigerator according to one of the preceding claims, characterized in that the channels ( 9 ) between inside ( 13 ) the Wall ( 11 ) and outside ( 12 ) the Wall ( 11 ) at an acute angle (alpha), preferably from 0.1 ° to 20 °, to the inside ( 13 ) or the outside ( 12 ) the Wall ( 11 ) are guided. Refrigerator according to one of the preceding claims, characterized in that the channels ( 9 ) are running. Refrigerator according to claim 7, characterized in that the channels ( 9 ) by an embedded in the insulation hollow chamber double-wall plate ( 6 ) are formed. Refrigerator according to one of the preceding claims, characterized in that the flow-through wall ( 11 ) is a roof surface. Refrigerator according to one of the preceding claims, characterized in that the flow-through wall ( 11 ) is a floor surface. Refrigerator according to one of the preceding claims, characterized in that means ( 2 . 4 ) are provided for cooling by a introduced into the refrigerator cryogenic liquid gas, wherein the exhaust gas formed by evaporation of the liquid gas from the interior ( 14 ) of the refrigerator through the channels ( 9 ) can be directed to the outside. Refrigerator according to claim 11, characterized that the liquid gas is liquid nitrogen. Refrigerated vehicle with at least one refrigerator for the transport of goods according to one of the preceding claims.