CROSS-FLOW SPIRAL HEAT TRANSFER APPARATUS WITH SOLID BELT
A heat transfer apparatus for a product includes a housing having an internal chamber; a solid conveyor belt disposed within the internal chamber and arranged in a spiral configuration having upper and lower portions, the spiral configuration including an upper pathway within the upper portion, a lower pathway within the lower portion; a gas flow having an upper gas flow across the upper pathway, a lower gas flow across the lower pathway and in counter-flow to the upper gas flow, wherein the upper gas flow and the lower gas flow define a circulation loop; and a gas circulation device to induce the upper and lower gas flows along the circulation loop.
This application is a continuation-in-part of prior application Ser. No. 12/184,386, filed Aug. 1, 2008, which claims the benefit of U.S. Provisional Application No. 60/964,458, filed Aug. 13, 2007. The disclosures of the parent application Ser. No. 12/184,386, filed Aug. 1, 2008, and the Provisional Application No. 60/964,458, filed Aug. 13, 2007 are hereby incorporated by reference.
TECHNICAL FIELDThe present disclosure relates to a heat transfer system for cooling, chilling heating or otherwise removing heat from or supplying heat to products, such as for example food products.
BACKGROUNDIn some refrigeration systems, a line of products to be for example refrigerated is moved through the refrigeration system, along a spiral or helical pathway through the cold or chilling region. Systems in which products to be refrigerated follow a spiral or helical pathway through the cold region are conventionally termed spiral refrigeration systems. Related systems may be used to heat products.
One type of refrigeration system used in the industry to remove heat from products is a spiral refrigeration system. Unless otherwise noted, as used herein, “spiral” refers to both spiral and helix forms.
A single pass configuration spiral refrigeration system is one in which a gas such as cryogen is directed by fans to flow among the products to be cooled. The gas is then returned from the products to the fans through return gas conveyances in the system. In existing single pass systems, the return gas conveyances may consist of ductwork which do not contain products from which it is desirable to remove heat. Since there are no products to be cooled along the return ductwork path, single pass systems lose cooling capacity due to less efficient use of process volume along with the inefficiencies associated with maintaining the environment in this ductwork space. In addition, the large external return gas conveyors and ductwork add bulk and footprint area to known systems; further reducing cost-effectiveness of such systems.
It therefore remains desirable to provide for a more efficient system to cool and/or chill products, and heat and/or cook products in a spiral heat transfer system.
Embodiments of the subject matter are disclosed with reference to the accompanying drawings and are for illustrative purposes only. The subject matter is not limited in its application to the details of construction or the arrangement of the components illustrated in the drawings. Like reference numerals are used to indicate like components, unless otherwise indicated.
Discussion of the heat transfer system or apparatus embodiments is with respect to cooling and heating a product, and reference to or refrigeration system could similarly include references to a heating system.
Variables defining a spiral pathway include, but are not limited to, diameter, height and pitch. As used herein, a “tier” is the part of a helix corresponding to one full thread of the spiral.
In all the embodiments herein, return of the gas flow occurs within the product processing zone of the system, not at an exterior of the system.
In all embodiments, the present system can also be used in a manner of heat transfer to also heat or cook products, such as food products. The higher the velocity of the gas being employed to pass over the products, the greater the increase in heat transfer at the products.
In all embodiments, a drum which moves the spiral conveyor belt cooperates with the spiral belt to create a bifurcated pathway for the gas, which pathway has a width equal to the width of the conveyor belt upon which the products are transported so that maximum heat transfer can be achieved from the gas flows.
In the refrigeration system embodiments herein in which heat is transferred from a product to be refrigerated to a flowing refrigeration fluid, one mode of cooling the product to be refrigerated is forced convection. In forced convection, the heat transfer coefficient is a function of the flow velocity of the refrigeration fluid. Heat transfer for cooling objects also includes a factor that the higher the velocity of gas used to effect heat transfer, the greater the heat transfer rate.
A refrigeration fluid may also be called a “cryogen”. One such cryogen, nitrogen gas, can be as cold at −320° F., or as dictated by the minimum temperature at which the gas exists in its gaseous state.
In addition to the efficiency benefits achieved by reducing disused regions, the size of the freezing system may be made significantly smaller because the refrigeration medium, such as a gas, is returned to the main blowers along the product pathway or in the product processing zone. Dedicated external return chambers and related ductwork are not necessary. This results in a savings in overall system cost. In addition, a lower amount of structural material is required to be cooled down which results in a secondary efficiency improvement.
Referring to
The spiral belt 50 provides for a spiral pathway. The spiral pathway includes an upper pathway 52 of the tiers 51 within the upper portion 16; and a lower pathway 54 of the tiers 53 within the lower portion 18. The product is transported upon the tiers 51, 53 of the belt 50. The drum 40 drives the belt 50 along the spiral or helical path.
The baffle 30 separates the upper pathway 52 from the lower pathway 54. The baffle 30 works in conjunction with the drum 40 to create the upper pathway 52 and the lower pathway 54 to each have a width equal to a width of the belt 50. This is because gas flow 25 does not flow through the drum 40, but rather is bifurcated by the drum 40 as shown in
In operation, and referring to
As shown in
In effect, the product is subjected to a two-pass or dual-pass flow of the gas 25. The cryogen gas flow 25 is restricted for flow across a width of the tiers 51, 53 of the conveyor belt 50, such that none of the cryogen gas is wasted on heat transfer at unnecessary portions of the freezer system 10.
The construction and operation of the embodiment shown in
In the cross-flow spiral refrigeration system 10 of
Thus, the two-pass configuration of the present system 10 may require only about 50% of the conventional airflow used in conventional airflow schemes, such as one-pass flow configurations.
In addition to the operational efficiency benefits achieved by the system 10, the size of the freezing system 10 may be made significantly smaller because the gas is returned to the blowers 20A, 20B through the upper and lower pathways. Separate gas return chambers and ductwork are not necessary, thereby providing for a smaller “footprint” for the system 10. This results in a significant savings in overall system cost.
As shown in
The system 110 shown in
Disposed within the space 114 is a drum 140 about which a spiral conveyor belt 150 is constructed and arranged for operation, the belt 150 being driven along the spiral or helical path by the drum 140. The drum 140 is impervious to fluid flow and bifurcates the gas flow 125 similarly to that which occurs with respect to the embodiment of
The internal chamber 114 consists of an upper portion 116 and a lower portion 118. The upper portion 116 and lower portion 118 are segregated from each other by a baffle 130 which extends along the internal chamber 114 of the housing 112. The upper portion 116 of the internal chamber 114 contains the upper pathway 152, while the lower portion 118 of the internal chamber 114 contains the lower pathway 154. The conveyor belt and its tiers 151, 153 move between the upper and lower pathways 152, 154.
Disposed in the upper portion 116 of the internal chamber 114 is a blower or fan 122A, while disposed at the lower portion 118 of the internal chamber 114 is another blower or fan 122B. Fans 122A, 122B may be arranged at different sides of the housing 112, such as at opposed sides of the housing 112. In addition, one of the fans, such as the fan 122A, is disposed in the upper portion 116, while the other blower such as the fan 122B is disposed in the lower portion 118. The baffle 130 surrounds the drum 140 and prevents fluid flow 125 between and among the upper portion 116 and the lower portion 118, except for areas of the baffle 130 shown generally at 131 and 132. The areas 131, 132 are those areas permitting gas flow 125 to occur between the lower portion 118 and the upper portion 116. This can be as a result of the construction of the baffle 130 extending up to only that point in the interior space 114 where the baffle meets the fans 122A, 122B, or apertures (not shown) may be provided in the baffle 130 to enable the gas flow 125 to be drawn from the lower portion into the upper portion via the fan 122A, and from the upper portion 116 into the lower portion 118 via the fan 122B. In either arrangement there is provided the continuous circulatory effect between and among the upper and lower portions 116, 118.
The conveyor belt 150 is arranged to extend between the lower portion 118 and the upper portion 116. At least one and preferably a plurality of the tiers 151 of the belt 150 are disposed at any given time in the upper portion 116. At least one and preferably a plurality of the tiers 153 of the belt 150 are disposed in the lower portion 118 at any given time.
As shown in
Although the perspective of
Conduits 124, 126 are in communication with the blower chambers 120, 170 to “charge” the system 110 with a cooling or heating fluid as necessary. The conduits 124, 126 are connected to a source (not shown) of cooling or heating fluid and may be in communication with other areas of the chamber 114.
The system 110 shown in
In the embodiments of
In the embodiments shown in
Referring to another embodiment of the invention at
Referring to
The spiral belt 250 provides for the spiral pathway 226. The spiral pathway 226 includes an upper pathway 252 of the tiers 251 within the upper portion 216; and a lower pathway 254 of the tiers 253 within the lower portion 218. The product is transported upon the tiers 251, 253 of the belt 250. The drum 240 drives the belt 250 along the pathway which resembles a spiral or helical pathway.
The blower 222 is provided with a sidewall 228 which forms an entrance cone in communication with a return airflow at the lower portion 218. As shown in
The tier X separates the upper pathway 252 from the lower pathway 254. The tier X coacts with the entrance cone to create the upper pathway 252 and the lower pathways 254 to each have a width equal to a width of the belt 250. This is because gas flow 225 does not flow through the drum 240 or the belt 250, but rather is bifurcated by the drum into separate streams (discussed below) flowing about and exterior to the drum and then into the return chamber 260. The tier X is continuous around the drum 240, and extends into the blower chamber 220 and the return chamber 260. In this manner of construction, the gas flow 225 is directed from the blower chamber 220 across and onto the product being transported on the tiers 251 of the belt 250 in the upper pathway 252, through the return chamber 260 and then back in counter flow along the lower pathway 254 for further contact with the product on the conveyor belt 250, whereupon the gas 225 flows to the blower chamber 220 for continuous circulation. Replenishment of fresh cryogen to the system 210 is provided to the blower chamber 220 via conduit 224. The conduit 224 is in communication with a source of cryogen (not shown) such as for example liquid or gaseous carbon dioxide (CO2), or liquid nitrogen (N2). The conduit 224 may be disposed at other locations of the apparatus 210 for introduction of the cryogen (or heating fluid) thereto.
The upper pathway 252 is a helical path comprising a plurality of tiers such as for example three tiers 251 of the belt 250, while the lower pathway 256 is a helical path comprising a plurality of tiers such as for example three tiers 253 of the belt 250, although the number of tiers is merely illustrative and not intended as a limitation. The upper pathway 252, the return chamber 260, the lower pathway 254, and the blower chamber 220 define a circulation loop for the gas 225. The blower 222 to induce gas flow can be a fan, blower, compressor or any other suitable means. The blower 222 is constructed and arranged for operation in or communication with the blower chamber 220.
In operation, and referring to
As shown in
In effect, the product is subjected to a two-pass or dual-pass flow of the cryogen. The flow 225 is restricted for flow across a width of the tiers 251, 253 of the conveyor belt 250, such that none of the cryogen gas is wasted on heat transfer at unnecessary portions of the freezer system 210.
The construction and operation of the embodiment shown in
In the cross-flow spiral heat transfer apparatus 210 of
Alternatively, the apparatus 210 as a heat transfer apparatus provides for the continuous, uniform passing of a heating or cooking gas over the product on the belt 250.
Thus, the two-pass configuration of the present system 210 may require only about 65% of the airflow used in conventional airflow arrangements, such as one-pass flow configurations.
In addition to the operational efficiency benefits achieved by the apparatus 210, the size of the freezing apparatus 210 may be made significantly smaller because the gas is returned to the blowers 220 through the upper and lower pathways. Separate gas return chambers and ductwork are not necessary, thereby providing for a smaller “footprint” for the apparatus 210. This results in a significant savings in overall system cost.
While the present subject matter has been described above in connection with illustrative embodiments as shown in the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiments for performing the same function without deviating therefrom. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments may be combined to provide the desired characteristics. Variations can be made without departing from the spirit and scope of the invention. Therefore, the cross-flow spiral heat transfer system should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the attached claims.
Claims
1. A heat transfer apparatus for a product, comprising:
- a housing having an internal chamber;
- a solid conveyor belt disposed within the internal chamber and arranged in a spiral configuration having upper and lower portions, the spiral configuration, comprising: an upper pathway within the upper portion, a lower pathway within the lower portion;
- a gas flow, comprising: an upper gas flow across the upper pathway, a lower gas flow across the lower pathway and in counter-flow to the upper gas flow, wherein the upper gas flow and the lower gas flow define a circulation loop; and
- a gas circulation device to induce the upper and lower gas flows along the circulation loop.
2. The apparatus of claim 1, wherein the upper gas flow and the lower gas flow are of substantially uniform velocity.
3. The apparatus of claim 1, wherein the upper portion and the upper pathway have a similar width, and the lower portion and the lower pathway have a similar width.
4. The apparatus of claim 1, wherein the gas circulation device comprises at least one fan disposed in at least one of the upper and lower portions.
5. The apparatus of claim 1, further comprising a drum disposed in the internal chamber and extending between the upper and lower portions, and about which is arranged the solid conveyor belt in the spiral configuration.
6. The apparatus of claim 5, wherein the drum comprises an outer sidewall adjacent the solid conveyor belt and impervious to the upper and lower gas flows.
7. The apparatus of claim 1, wherein the upper and lower gas flows comprise gas selected to reduce a temperature of the product.
8. The apparatus of claim 7, wherein the gas comprises a cryogenic gas selected from the group consisting of carbon dioxide, nitrogen and combinations thereof.
9. The apparatus of claim 1, wherein the upper and lower gas flows comprise a gas selected to heat the product.
10. The apparatus of claim 1, wherein the circulation loop is arranged in the internal chamber.
11. The apparatus of claim 1, wherein the product comprises a food product.
Type: Application
Filed: Oct 24, 2011
Publication Date: Nov 1, 2012
Inventors: Stephen A. McCormick (Warrington, PA), Michael D. Newman (Hillsborough, NJ)
Application Number: 13/279,737
International Classification: F28D 15/00 (20060101);