Variable surface area heat exchanger

ES 2 545 652 T3

DESCRIPTION

Variable surface heat exchanger

Technical field of the present invention

The present invention relates to an apparatus that can adjust a heat transfer surface during refrigeration or freezing processes. GB 2 053 444 A describes a heat transfer apparatus having the features of the preamble of claim 1.

Background of the present invention; prior art

Known freezing systems used, for example, in transit refrigeration (ITR) include mechanical compression refrigeration driven by diesel fuel engines, tanks filled with CO2 dry ice, or liquid CO2 that is vaporized through heat exchangers. heat mounted inside a refrigerated space and then discharged to an outside space.

The air within the refrigerated space is cooled by forced or natural convection on the surface of the heat exchanger for the mechanical compression refrigeration system, for the dry ice tank or for the liquid CO2 heat exchanger. The air temperature inside the refrigerated space will generally be 0 ° F (-18 ° C) for a frozen food product or 34 ° F (1 ° C) for a refrigerated product.

Precise control of the air temperature in space using a mechanical compression refrigeration system is difficult due to a minimal temperature difference between the refrigerant temperature and the desired air temperature and thus a transfer rate of limited heat. In addition, for trailer-installed refrigeration systems, trailer doors are frequently opened for deliveries, often providing a rapid increase in heat load on the trailer.

Precise control of air temperature in space is difficult for dry ice tank systems because the heat exchanger surface always remains at -109 ° F (-78 ° C), and once that temperature is reached , the heat transfer cannot be reduced. Therefore, the air temperature will drop below the desired set value.

Failure to maintain proper temperature control in the space can cause the temperature to drop below what is acceptable for the product to be transported, thereby damaging the product.

In order to compensate for the anticipated increase in heat load, the temperature of the air within the space will often be reduced to a temperature that is less than desirable for the product being transported. This makes food products especially susceptible to damage, and therefore will likely cause the efficiency of the system to decrease in order to obtain the proper temperature control for the space.

Known systems also have a cold surface on the heat exchanger that tends to become covered in frost that has condensed from outside air in the refrigerated space it is allowed to enter (such as when the trailer doors are opened for access). to the product), thereby causing a variation in the rate of heat transfer and the potential loss of temperature control for the space.

Description of the present invention: object, solution, advantages

From the disadvantages and deficiencies described above and taking into account the analyzed prior art, an object of the present invention is to eliminate the accumulation of frost on the surface of the heat exchanger and to provide a more uniform and constant temperature of the product and of the space. of refrigeration.

This object is achieved by a heat exchange apparatus comprising the features of claim 1. Advantageous embodiments and convenient improvements of the present invention are described in the dependent claims.

In one embodiment of the present invention, a heat exchange apparatus is described that includes

- a housing having a side wall defining a chamber in the housing for containing a cryogen; Y

a first insulation element movably mounted to cooperate with the side wall, the first insulation element being movable to a position to expose or cover a selected part of the side wall in order to provide a heat transfer effect.

ES 2 545 652 T3

According to an advantageous embodiment of the present invention, cryogen is a substance selected from the group consisting of dry ice and liquid carbon dioxide (CO2).

In accordance with a convenient embodiment of the present invention,

- an inlet is formed on one side of the housing through which dry ice can be introduced into the chamber, and

- a ramp is functionally associated with the entrance to guide the dry ice to the entrance.

According to a preferred embodiment of the present invention

- an inlet tube extends through the chamber to receive the liquid carbon dioxide, and

- at least one nozzle is operatively associated with the inlet tube and in communication with the liquid carbon dioxide to release cryogen vapor within the chamber.

According to a preferred embodiment of the present invention, a second isolation element is mounted in the chamber

- the second insulating element isolating a part of the side wall, and

- the first insulation element and the second insulation element cooperating with respect to the side wall to provide a selected amount of heat transfer effect to the side wall.

According to an advantageous embodiment of the present invention,

- the first insulation element is made of a material selected from the group consisting of stainless steel, aluminum, stainless steel with a foam core, stainless steel with a polystyrene core, aluminum with a foam core and aluminum with a foam core polystyrene; me

- the second insulation element is made of a material selected from the group consisting of high-density foam and polystyrene.

According to a convenient embodiment of the present invention, the side wall comprises a circular cross section and the first insulation element has a first arcuate shape that conforms to an outer surface of the side wall, and the second insulation element has a second arcuate shape that conforms to an inner surface of the side wall.

According to a preferred embodiment of the present invention, a first length of the first arcuate shape and a second length of the second arcuate shape total 360 °.

According to a preferred embodiment of the present invention, the heat exchange apparatus comprises

- a cover that has a space inside to receive the accommodation,

- an entry into communication with the space and

- an exit in communication with the space.

According to an advantageous embodiment of the present invention, at least one fan is operatively associated with the inlet to direct the flow of air to the inlet and into the space to communicate with the housing.

In accordance with a convenient embodiment of the present invention, the first isolation element comprises a first plurality of teeth extending therefrom.

In accordance with a preferred embodiment of the present invention, the heat exchange apparatus comprises a drive apparatus having a drive gear with a second plurality of teeth sized and shaped to cooperate with the first plurality of teeth of the first insulating element.

In accordance with a preferred embodiment of the present invention, the first isolation element comprises a blade edge for removing frozen cryogen from the side wall.

According to an advantageous embodiment of the present invention, the heat exchange apparatus comprises a container in which the housing is mounted to provide the effect of heat transfer to an interior of the container.

ES 2 545 652 T3

In accordance with a convenient embodiment of the present invention, the housing is functionally associated with a refrigeration container in transit.

The present invention finally relates to the use of at least one heat exchange apparatus as described above in at least one truck, a trailer, a car, a wagon, a flatbed truck, a barge, a compartment, a container shipping container or other floating container or other transport vehicle to provide refrigeration in transit (ITR) or other means of transport to provide refrigeration in transit (ITR).

Brief description of the drawings

For a more complete understanding of the descriptions of embodiments of the present invention and as already discussed above, there are several options to incorporate as well as to enhance the teachings of the present invention in an advantageous manner. For this purpose, reference may be made to the claims dependent on claim 1; Other improvements, features and advantages of the present invention are explained in more detail below with reference to preferred embodiments by way of non-limiting example and to the accompanying drawing figures taken in conjunction with the description of the embodiments, of which:

Figure 1 shows a cross-sectional side view of an embodiment of a variable surface heat exchanger;

Figures 2 to 5 show cross-sectional end views of parts of the embodiment of Figure 1 in various stages of operation;

Figure 6 shows a top perspective view of the embodiment of the heat exchanger with a mechanical drive assembly;

Figure 7 shows a partial cross section of the embodiment of Figure 6;

Figure 8 shows an isometric view of the embodiment of the heat exchange apparatus; Y

Figure 9 shows the embodiment of the heat exchange apparatus assembled for operation in a container.

In the accompanying drawing figures, equipment that is similar is indicated by the same reference numerals throughout the description from Figure 1 to Figure 9.

Detailed description of the figures in the drawings; best mode of carrying out the present invention

In order to avoid unnecessary repetition, the following description, as it relates to the features, characteristics and advantages of the present invention, refers, unless otherwise indicated, to all corresponding embodiments of the present invention.

With reference to FIG. 1, an embodiment of a variable surface heat exchanger is shown generally by reference numeral 10. The heat exchange apparatus 10 includes a side wall 12 to define a space 14 or a chamber within the apparatus. . Side wall 12 has an outer surface 16 and an inner surface 18. Space 14 contains dry ice 20 or, alternatively, carbon dioxide gas (CO2) can be introduced into the space as described hereinafter.

The heat exchanger 10 can be manufactured from stainless steel, aluminum or plastic and has a tube-like shape with a cross-sectional diameter of for example about six inches, while a width of the heat exchanger extends substantially across of a width of a container 22 in which the heat exchanger is arranged for operation.

A cover 24 is provided for the heat exchanger 10 to prevent personnel or products in the containment space 23 of the container 22 from accidentally coming into contact with the heat exchanger, and to provide a path by way of directing air flow 26 over the surface 16 of the heat exchanger. Cover 24 can be mounted to container 22 by, for example, mechanical fasteners (not shown).

The heat exchanger 10 has a part thereof insulated to prevent heat transfer to the air flow 26 which is directed to the heat exchanger. An insulation layer 28 or element is mounted on the inner surface 18 of the side wall 12 and covers a selected portion of said inner surface. The insulation layer 28 can be made of high density foam or polystyrene, or it can be vacuum insulated. The insulation layer 28 is attached to the inner surface 18 of the side wall 12 or can be an integral part thereof.

ES 2 545 652 T3

As shown by way of example only with respect to Figures 1 to 5, the insulation layer 28 is mounted to cover half of the inner surface 18 of the side wall 12. The side wall 12 is shown with a circular cross section. and thus, insulation layer 28 is provided with an arcuate or curved shape to fit inside surface 18 of side wall 12. The remaining part of the inner surface 18 remains uninsulated and therefore provides heat transfer when the air flow 26 is exposed to the side wall 12.

A movable insulated shield 30 or element is arranged to rotatably move along the outer surface 16 of the side wall 12. The shield 30 is arcuate in shape in order to function as described below. Referring also to Figures 2 to 5, it is seen that movement of shield 30 relative to and along outer surface 16 can be obtained, providing additional insulation to that portion of side wall 12 that is not provided. insulation layer 28.

The arcuate or curved shape of shield 30 allows the shield to engage outer surface 16 to move along that surface. Shield 30 can therefore either completely cover the uninsulated half of side wall 12, as shown in Figure 4, thus stopping heat transfer; or it can be folded completely flush with the insulation layer 28 on an opposite side of the side wall as shown in Figure 2, thus providing maximum heat transfer.

Therefore, the movable shield 30 can be positioned as shown in Figures 2 to 5 to provide various levels of heat transfer, depending on the position of the shield 30 with respect to the insulation layer 28. This form of manufacture of the exchanger The heat transfer surface 10 provides the variable heat transfer surface and the variable heat transfer rate for the air flow 26 that is within the refrigerated space of the container 22.

As shown in Figure 4, a length of each of the insulation layer 28 and shield 30 combined can be equal to 360 °. However, the heat exchanger 10 can certainly be provided with an insulating layer 28 having a length of for example 270 °, while the movable shield 30 would have a length of 90 °.

What is required is that the combined lengths of each of the insulation layer 28 and the shield 30 add up to a total of at least 360 °, if the chamber 14 has a circular cross section, so that when the shield is moved to In the position shown in Figure 4, the apparatus 10 does not provide heat transfer.

The degree of cooling in container 22 provided by heat exchanger 10 can be controlled by rotating shield 30 along outer surface 16 of side wall 12 to thereby vary the exposed outer surface portion. The shield 30 is mounted on the side wall 12 so that when the shield is moved or rotated, it hugs or slides along the outer surface 16 of the side wall.

Shield 30 can be made from a material similar to that used to make insulation layer 28. If shield 30 is made of stainless steel or aluminum, it could have a high-density foam or polystyrene core; or even a vacuum insulated core.

Shield 30 is also provided with at least one blade edge 32. When shield 30 is moved, for example, counterclockwise, as shown in Figure 1 and Figure 3, the cutting edge Blade 32 scrapes or shaves off any frost that may have accumulated or formed on the outer surface 16 when it was exposed to air flow 26 for heat transfer.

Therefore, rotating the movable shield 30 to the position from Figure 2 to Figure 3, to provide the necessary amount of heat transfer, will cause the knife edge 32 to scrape and clean the outer surface 16 so frost build-up is prevented and removed and the efficiency of heat exchanger 10 is maintained.

Removal of accumulated frost is also necessary to be able to move shield 30 into position and out of position relative to insulation layer 28. If too much frost is allowed to accumulate, shield 30 will not be able to rotate or move to the desired position with respect to the insulation layer 28 in order to provide the necessary amount of heat transfer.

As shown in Figure 1, a fan 34 or fans can be used to provide air flow 26 through cover 24 to contact heat exchanger 10.

Still referring to Figures 2 to 5, Figure 2 shows the heat exchanger 10 with the movable shield 30 fully folded in an overlapping position with respect to the insulation layer 28 so that the maximum transfer effect can be provided. of heat. Figure 3 depicts the movable shield 30 moved to one position, as indicated by arrow 36 to have the reduced heat transfer effect.

Figure 4 shows the shield 30 fully moved into a position to cover the remaining exposed portion of the outer surface 16 so that the heat exchanger 10 does not provide any heat transfer effect.

ES 2 545 652 T3 heat. Alternatively, the shield 30 can be moved clockwise, as shown by arrow 38, which will eventually bring the shield to the position shown in Figure 4.

With reference to Figures 6 and 7, the movement or rotation of the shield 30 can be provided by known mechanical or electrical devices, such as those using a servo motor 48.

The movable shield 30 is provided at one end thereof with a gear flange 54 or collar having at least a portion thereof provided with a plurality of teeth 56. The teeth 56 extend substantially along one edge of the gear flange 54, and certainly at least to a point necessary to move shield 30 into the necessary position relative to insulation layer 28 in order to provide the desired amount of heat transfer.

The servomotor 48 has a shaft 58 extending therefrom which has at its end a gear 60 with a plurality of teeth 62 sized and shaped to align and cooperate with the teeth 56 of gear flange 54. With this construction, the servomotor 48 drives the shaft 58 and in turn the gear 60; The teeth 62 cooperate with the teeth 56 of the gear flange 54 to rotate the movable shield 30 to the necessary position with respect to the side wall 12. The joint action of the insulation layer 28 and the shield 30 adjusts the effect of heat transfer that can be provided on the side wall 12.

Apparatus 10 can be filled or charged with cryogen in different stages. An end part 51 of the side wall 12 can be provided with a door 50 or hatch through which dry ice 20 can be introduced into the space.

14. A chute 52, a loading funnel or a hopper is mounted on the end portion 51 that is aligned with the door 50 so that dry ice 20 in the form of granules can be introduced into the space 14 to provide the effect of transfer of hot.

Alternatively, the cryogen introduced into apparatus 10 may be provided as liquid cryogen introduced through an inlet tube 40 or fill tube that may extend substantially through space 14, as shown in Figure 8, and have a plurality of nozzles 42 in communication therewith, as shown in Figure 7. Liquid cryogen is discharged through nozzles 42 into chamber 14 where it expands as a gas and solid phase to provide the heat transfer effect for the side wall.

12. An exhaust pipe 44 is withdrawn from space 14 through outlet pipe 46. Liquid cryogen can be introduced as liquid carbon dioxide (CO2) into fill pipe 40.

As shown in Figure 9, the heat exchanger embodiment 10 is arranged to operate in the container 22; see also Figure 1. Air flow 26 in container 22 is drawn in by fans 34 to pass through and contact the outer surface 16 of the heat exchanger. Naturally, that part of the outer surface 16 to be exposed is controlled by the movement of the movable shield 30 with respect to the side wall 12.

Airflow 26 is cooled and discharged as shown by arrows 64 to circulate in and through containment space 23. As the cooled air flow 64 begins to warm from its exposure to the products in the containment space 23, such warm air begins to rise as represented by arrows 66, and returns to and is drawn in as in the air flow 26 towards the heat exchange apparatus 10 to subsequently pass over the heat exchanger.

It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art can make variations and modifications without departing from the spirit and scope of the invention. All of these variations and modifications are intended to be included within the scope of the invention as described and claimed herein. Furthermore, all of the described embodiments are not necessarily in the alternative, since various embodiments of the invention can be combined to provide the desired result.

List of reference numbers heat exchange apparatus, in particular heat exchange apparatus with variable surface side wall of the heat exchange apparatus 10 chamber or space inside the heat exchange apparatus 10 outer surface of the side wall 12 surface inside side wall 12 dry ice

ES 2 545 652 T3 container container containment space 22 cover air flow second insulating element, in particular insulating layer first insulating element, in particular moving element with insulation, for example movable shield with insulated blade edge fan movement of the movable insulated element 30 movement of the movable insulated element 30 clockwise inlet pipe or filling pipe nozzle exhaust pipe outlet pipe drive device, in particular entrance servomotor, in particular door or hatch end part of side wall 12 ramp, charging funnel or hopper gear flange or collar gear flange tooth or collar 54 shaft gear, in particular, drive gear gear tooth 60 cooled air flow tempered air (more tempered)