ADSORPTION HEAT EXCHANGER

Abstract

An adsorption heat exchanger may comprise a stack of alternating adsorption layers and heat transfer layers. Separator plates may separate the adsorption layers from the heat transfer layers. The adsorption layer may include a first corrugated sheet positioned between and brazed to the adsorption zone facing side of two separator sheets. The first corrugated sheet and the exposed portions of the adsorption zone facing side of the separator sheets may be coated with an adsorptive material. The heat transfer layer may include a second corrugated sheet positioned between and brazed to the heat transfer zone facing side of two separator sheets. The second corrugated sheet may be oriented about 90° to the first corrugated sheet.

Description

BACKGROUND OF THE INVENTION

The present invention generally relates to adsorbent coated heat exchangers and, more particularly, to adsorption heat exchangers as used in adsorption devices such as adsorbers and adsorption heat pumps.

Heat exchangers can be used for transporting heat. The heat exchanger can be operationally connected to a heat source and a heat sink. In some systems, such as an air cycle pack of an environmental control system, the heat exchanger can be connected to the heat source via a heat transfer fluid loop and a flow of ram air may serve as the heat sink. In some systems, such as vapor cycle systems, both the heat source and the heat sink may be connected to the heat exchanger via fluid loops.

A heat exchanger is conventionally used to transport heat from one fluid to another. The adsorbent heat exchangers of the present invention do not serve that general purpose. Instead the present invention is an improvement in the field of adsorbers which function efficiently to adsorb a working fluid when cooled and can desorb that same working fluid efficiently when heated. Sensible heat transfer from a heat transfer fluid takes place in an adsorber heat exchanger and serves to efficiently change the temperature and enthalpy, and working loading of the adsorbent material that coats the adsorber heat exchanger.

A heat exchanger for use with two fluid loops is described in U.S. Pat. No. 6,318,456. The disclosed heat exchanger is of the cross current design and comprises a plurality of stacked plates that form a first flow path and a second flow path. Heat transfer occurs as fluid from one loop passes through the first flow path and fluid from the other loop passes through the second flow path. Generally, both fluid loops include a pump to pump the fluids through the heat exchanger. Although such devices may be efficient they utilize high quality shaft work as a high power input.

Heat exchangers that include an adsorptive material within one flow path can provide a reduction in power input. An adsorption heat exchanger is disclosed in U.S. Pat. No. 5,585,145. The described adsorption heat exchanger comprises a tube and lamellas (plates) design. The tube is positioned through holes in the lamellas. The heat exchanger is designed such that one fluid (e.g. a heat transfer fluid) can pass through the tube and a second fluid (e.g. an adsorbate) can pass over the lamellas. After assembly the lamellas and the outside surface of the tube (outside surface of the heat transfer fluid flow path) are wash coated with an adsorptive material. The adsorptive material desorbs the second fluid when heated and adsorbs the second fluid when cooled. Although the described adsorption heat exchanger can reduce power input, the adsorptive material tends to build up at the tube-plate interface during coating application. The uneven adsorptive coating layer reduces efficiency. Additionally, a reduction in adsorption heat exchanger dimensions is desired for some applications.

Adsorption heat exchangers having a more evenly applied adsorptive material have been described. In U.S. Pat. No. 6,102,107, the plates are laminated with an adsorptive material/fiber matrix paper prior to assembly of the tube-plate heat exchanger. The described laminate paper design avoids the tube-plate interface build up of the '145 patent. Although the laminate paper can provide a more even layer of adsorptive material, both heat and mass transfer are negatively affected by the thickness of adsorptive material/fiber matrix paper.

As can be seen, there is a need for improved adsorption heat exchangers. Adsorption heat exchangers having improved adsorption coating thickness uniformity and increased adsorptive material surface area are needed. Further, adsorption heat exchangers having increased adsorption/desorption efficiency, higher heat transfer efficiency and smaller size are needed.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an apparatus comprises at least one adsorption layer having an adsorption zone corrugated sheet, at least a portion of the adsorption zone corrugated sheet having an adsorptive material coating; at least one heat transfer layer having a heat transfer zone corrugated sheet, the heat transfer layer positioned parallel to the adsorption layer; and a separator plate positioned between and in contact with the adsorption zone corrugated sheet and the heat transfer zone corrugated sheet.

In another aspect of the present invention, an apparatus comprises an adsorption zone corrugated sheet having a plurality of adsorption zone fins and a plurality of adsorption zone contact portions; a heat transfer zone corrugated sheet positioned parallel to and oriented 90° of the adsorption zone corrugated sheet; a separator sheet having an adsorption zone facing side and a heat transfer zone facing side, the separator sheet positioned between and in contact with the adsorption zone corrugated sheet and the heat transfer corrugated sheet; and an adsorptive material coating in contact with at least one adsorption zone fin.

In a further aspect of the present invention, an apparatus comprises a plurality of adsorption layers; a plurality of heat transfer layers, the plurality of adsorption layers and the plurality of heat transfer layers positioned such that a stacked arrangement of alternating adsorption layers and heat transfer layers is formed, the plurality of adsorption layers and the plurality of heat transfer layers forming at least one adsorption layer/heat transfer layer pair; and a separator plate positioned between and in contact with the adsorption layer/heat transfer layer pair.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a sorptive cooling system according to one embodiment of the present invention;

FIG. 2a is a perspective view of an adsorption heat exchanger according to one embodiment of the present invention;

FIG. 2b is a close-up view of a portion of FIG. 2a;

FIG. 2c is a close-up view of another portion of FIG. 2a;

FIG. 3 is a perspective view of a portion of an adsorption heat exchanger according to one embodiment of the present invention;

FIG. 4 is a rotated view of FIG. 3;

FIG. 5 is a flow chart of a method of transferring heat between a flow of adsorbate and a flow of heat transfer fluid according to an embodiment of the present invention;

FIG. 6 is a plot of specific power as a function of cycle time according to one embodiment of the present invention;

FIG. 7 is a table of design parameters for an adsorption heat exchanger according to one embodiment of the present invention;

FIG. 8 is a diagram of the geometry of the adsorption heat exchanger of FIG. 7;

FIG. 9 is a table of sensitivity results on coating thickness variations for an adsorption heat exchanger according to one embodiment of the present invention; and

FIG. 10 is a table of design and performance parameters for an adsorption heat exchanger according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Broadly, the present invention provides adsorption heat exchangers for adsorption heat pumps and adsorption applications. Embodiments of these exchangers are not in themselves intended to promote heat transfer in a general sense, rather they are intended to enhance the transport of sensible heat from a heat transfer fluid into the adsorbent coating applied to the plurality of adsorbent layers, these exchangers are thus efficient at adsorbing and desorbing a working fluid such as water, and methods for using the same. Embodiments of the present invention may find beneficial use in industries such as the automotive, electricity generation and aerospace industries. Embodiments of the present invention may be useful in applications including adsorption refrigeration systems, adsorption based air conditioning systems and environmental control systems. Embodiments of the present invention may be useful in any heat transport application where in it is desired to efficiently heat or cool an adsorbent mass to promote adsorption or desorption of a working fluid. Such adsorbent heat exchangers may find use in applications including, but not limited to, heat transport for automobile air conditioning systems.

In one embodiment, the present invention provides an adsorption heat exchanger having a stack of alternating adsorption layers and heat transfer layers. The adsorption heat exchanger can comprise a stack of alternating corrugated sheets and separator plates. The corrugated sheets can be oriented in an alternating manner to provide an adsorption flow path in one direction and a heat transfer flow path in another direction (about 90° to the adsorption flow path). The surfaces defining the adsorption flow path can be coated with an adsorptive material. Unlike the prior art tube-lamellas design, the present invention can comprise a plate-corrugated sheet-plate design. For some embodiments, the plate-corrugated sheet-plate design allows for enhanced primary surface area and more efficient heat and mass transfer.

Unlike the prior art that includes adsorptive paper laminates, the adsorptive material of the present invention can be applied directly to a brazed heat exchanger assembly, reducing production time. Additionally, the adsorptive material coating of the present invention can provide a reduction in coating thickness and attendant enhancement of both heat and mass transfer. Also unlike the prior art paper laminate designs, the outside surface of the heat transfer fluid flow path of the present invention can be coated with adsorptive material, which may further increase adsorptive material surface area.

Moreover, unlike the prior art wherein the heat transfer fluid flow path comprises a tube, the heat transfer fluid flow path of the present invention can include a corrugated sheet that extends between and in contact with two separator plates. The corrugated sheet can form a plurality of fins running parallel to the flow of heat transfer fluid. The fins can increase heat transfer to the adsorption layer without adversely affecting the flow of the heat transfer fluid.

Embodiments of the present invention may include an adsorption heat exchanger 40 designed to thermally connect with a sorptive cooling system 41, as depicted in FIG. 1. The sorptive cooling system 41 can include the adsorption heat exchanger 40, a condenser 42 and an evaporator 43. The adsorption heat exchanger 40 can be operationally connected to a heat transfer fluid loop 44 and an adsorption loop 45.

During operation of the sorptive cooling system 41, heat from a flow of heat transfer fluid 69 (see FIG. 2a) flowing through the heat transfer fluid loop 44 can heat exchange with an adsorptive material coating 46 (see FIG. 3) and drive a flow of adsorbate 60 (e.g. a refrigerant) (see FIG. 2a) flowing through the adsorption loop 45. As the adsorptive material coating 46 is heated the flow of adsorbate 60 is caused to move toward the condenser 42. The flow of adsorbate 60 is desorbed from the adsorptive material coating 46 within the adsorption heat exchanger 40, driving adsorbate vapor to the condenser 42. In the condenser 42, the adsorbate vapor can be cooled and condensed. The adsorbate condensate can then pass to the evaporator 43 where the adsorbate condensate can be heat exchanged with a process stream 47 or space to be conditioned to revaporize the adsorbate condensate.

When further heating of the adsorptive material coating 46 no longer produces desorbed adsorbate from the adsorptive material coating 46, the adsorption heat exchanger 40 can be isolated and allowed to return to the adsorption conditions. When the adsorption conditions are established in the adsorptive material coating 46, the adsorbate vapor from the evaporator 43 can be reintroduced to the adsorption heat exchanger 40 to complete the cycle. Generally two or more adsorption heat exchangers 40 may be employed in a typical cycle wherein one adsorption heat exchanger 40 is heated during the desorption stroke and a second adsorption heat exchanger 40b is cooled during the adsorption stroke. The time for the completion of a full cycle of adsorption and desorption is known as the “cycle time.”

The adsorption heat exchanger 40, according to an embodiment of the present invention is shown in FIGS. 2a-c. The adsorption heat exchanger 40 can comprise at least one adsorption layer 50, at least one heat transfer layer 51 and a separator plate 52 positioned between and in contact with the adsorption layer 50 and the heat transfer layer 51. The adsorption heat exchanger 40 can comprise a plurality of adsorption layers 50 and a plurality of heat transfer layers 51. The adsorption layers 50 and heat transfer layers 51 may be positioned in a stacked arrangement of alternating adsorption layers 50 and heat transfer layers 51. In other words, one adsorption layer 50 may be positioned between two heat transfer layers 51; and one heat transfer layer 51 may be positioned between two adsorption layers 50. The adsorption heat exchanger 40 can comprise a plurality of separator plates 52 positioned such that one separator plate 52 is between and in contact with each adsorption layer/heat transfer layer pair. In other words, the separator plate 52 may be positioned between the adsorption layer 50 and the heat transfer layer 51. As defined herein, an adsorption layer/heat transfer layer pair may comprise an adsorption layer 50 and a heat transfer layer 51 positioned adjacent to one another.

The adsorption layer 50 may provide an adsorption flow passage 53 through the adsorption heat exchanger 40. The adsorption flow passage 53 may be in a direction parallel to an adsorption flow line 54. The heat transfer layer 51 may define a heat transfer flow passage 55 through the adsorption heat exchanger 40. The heat transfer flow passage 55 may be in a direction parallel to a heat transfer flow line 56. The adsorption flow line 54 may be about 90° from the heat transfer flow line 56.

The adsorption layer 50, as depicted in FIG. 3, may include an adsorption zone corrugated sheet 57 and the adsorptive material coating 46. The adsorption zone corrugated sheet 57 may be in contact with and extend between two separator plates 52. The adsorption zone corrugated sheet 57 may comprise a plurality of adsorption zone fins 58 and a plurality of adsorption zone contact portions 59. The adsorption zone fin 58 may be the portion of the adsorption zone corrugated sheet 57 that is perpendicular to and extends between the separator plates 52. The adsorption zone contact portion 59 may be the portion of the adsorption zone corrugated sheet 57 that is parallel to and in contact with the separator plate 52.

The adsorption zone fins 58 may be positioned about perpendicular to the separator plates 52 and may extend about parallel to the adsorption flow line 54. The adsorption zone fins 58 may direct the flow of adsorbate 60 (see FIG. 2a) through the adsorption heat exchanger 40 and may provide a support for at least a portion of the adsorptive material coating 46. The adsorption zone fin 58 may be in contact with and extend between two separator plates 52. For some applications the adsorption zone fin 58 may have an adsorption fin height 61 of between about 0.10 inches and about 0.5 inches. The adsorption fin height 61 may vary with application and may depend on factors including the composition of the adsorption zone fin 58 and the application. For example, for an automotive cooling system having adsorption zone fins 58 comprising aluminum, the adsorption fin height 61 may be about 0.250 inches. For some applications the adsorption zone fin 58 may have an adsorption fin thickness 64 of between about 0.001 inches and about 0.01 inches. The adsorption fin thickness 64 may vary with application and may depend on factors including the composition of the adsorptive material coating 46 and the application.

The density of adsorption zone fins (fins/inch) may vary with application and may depend on factors including the thickness of the adsorptive material coating 46 and the desired volume of the adsorption flow passage 53. The density of the adsorption zone fins 58 may be defined as the number of fins per inch of adsorption layer width as measured perpendicular to the adsorption flow line 54 and parallel to the separator plate 52. For some applications, the density of the adsorption zone fins 58 may be between about 7 fins/inch and about 28 fins/inch.

The adsorption zone contact portions 59 may be positioned about parallel to and in contact with the separator plates 52. The adsorption zone contact portions 59 may be brazed to an adsorption zone facing side 62 of the separator plates 52. The adsorption zone contact portions 59 may provide a support for at least a portion of the adsorptive material coating 46, as depicted in FIG. 3. In other words, one side of the adsorption zone contact portion 59 may be brazed to the separator plate 52 and the other side may be coated with the adsorptive material coating 46. For some applications the adsorption zone contact portions 59 may have an adsorption contact portion width 63 of between about 0.035 inches and about 0.15 inches. The adsorption contact width 63 is not an independent parameter. Once the density of the adsorption zone fins 58 and the adsorption fin thickness 64 have been specified the adsorption contact width 63 is a determinate value. The adsorption contact portion width 63 may vary and may depend on the desired density of the adsorption zone fins 58. The adsorption contact portion width 63 may be inversely proportion to the density of the adsorption zone fins 58.

For some applications, in lieu of the adsorption zone corrugated sheet 57, the adsorption layer 50 may comprise a plurality of adsorption zone fins 58 brazed directly to the separator plates 52. The adsorption zone fins 58 of the adsorption layer 50 may increase the surface area available for adsorptive material coating 46, thereby enhancing the adsorption/desorption efficiency of the adsorption heat exchanger 40.

The adsorption layer 50 may include two adsorption zone header bars 65, as depicted in FIG. 2a. The adsorption zone header bars 65 may be positioned parallel to the adsorption flow line 54. One adsorption zone header bar 65 may be positioned at one side of the adsorption layer 50 and the other adsorption zone header bar 65 may be positioned at the opposing side of the adsorption layer 50. The adsorption zone header bars 65 may be brazed to the separator plates 52 and may provide structural support to the adsorption heat exchanger 40.

The adsorption zone corrugated sheet 57, the adsorption zone fin 58, the adsorption zone contact portion 59 and adsorption zone header bar 65 each may comprise a material, such as but not limited to, aluminized mylar, a polymer composite, or a metal. Useful metals may include aluminum, copper, titanium, brass, stainless steel, other light metals and alloys with high conductivity, and graphite fiber composite materials. Components of the adsorption layer 50 may provide support for the adsorptive material coating 46.

The adsorptive material coating 46 of the adsorption layer 50 may define the adsorption flow passage 53, as depicted in FIG. 3. For some embodiments of the present invention, the adsorptive material coating 46 may define at least a portion of the adsorption flow passage 53. The adsorptive material coating 46 may be positioned on and in contact with the adsorption zone fins 58. Additionally, the adsorptive material coating 46 may be positioned on and in contact with the adsorption zone contact portions 59. Further, the adsorptive material coating 46 may be positioned on and in contact with at least a portion of the adsorption zone facing side 62 of the separator plates 52, as depicted in FIG. 3. The composition of the adsorptive material coating 46 may vary with application and may include an adsorbent, such as but not limited to silica gel, aluminas, silicas, zeolites, activated carbon, metal hydrides, metal chlorides, deliquescent salts such as Na₂SO4, Ca SO4, synthetic polymers, and mixtures thereof.

For some embodiments of the present invention, the adsorptive material coating 46 may include a zeolite. Zeolites may comprise microporous aluminosilicate compounds and may be commonly referred to as molecular sieves. Molecular sieves may have the ability to selectively adsorb molecules based primarily on a size exclusion process. This may be due their very uniform pore structure and molecular dimensions. The maximum size of the molecular or ionic species that can enter the pores of a zeolite may be controlled by the diameter of the pores. Zeolites have been widely used in industrial processes due to their structural stability and inherent exothermic reaction during adsorb/desorb cycles.

Useful adsorptive material coating compositions and methods for application may include the compositions and methods described in U.S. Pat. Nos. 5,120,694 and 5,518,977, both of which are incorporated herein by reference. Useful adsorptive coating application methods may comprise a step of heating a component to be coated, a step of contacting the surface of the component with a slurry comprising an adsorbent and a binder to form an adsorptive material coating 46, and a step of hardening the adsorptive material coating 46. For some applications, the step of contacting may comprise dipping the surface into the slurry or spraying the surface with the slurry.

The adsorptive material coating 46 may have an adsorptive coating thickness 77 (see FIG. 3) of between about 0.004 inches and about 0.040 inches. The adsorptive coating thickness 77 may be measured through the adsorptive material coating 46 and about perpendicular to the adsorption zone fin 67. For some applications, the adsorptive coating thickness 77 may be less than about 0.5 mm. The adsorptive coating thickness 77 may vary with application and may depend on factors including the dimensions of the adsorption zone fins 58, the desired dimensions of the adsorption flow passage 55 and the application. For some embodiments of the present invention a thin adsorptive coating (less than about 0.4 mm) may allow for a greater density of adsorption zone fins 58, increasing adsorptive material coating surface area.

The adsorptive material coating surface area (external or face area of the coating) may not affect the adsorptive surface area (surface area available for adsorption). Due to the micro-porous structure of the adsorptive material coating 46 the adsorptive surface area may be a function of the mass of adsorptive material coating applied as opposed to the external or face area of the coating. For a given mass of adsorptive material coating 46, increasing the external or face area of the coating may increase heat transfer efficiency because an increased face area may allow for a reduction in adsorptive coating thickness 77. The coating surface area (both the face area and the adsorptive surface area) may be increased further by the application of adsorptive material coating 46 to the adsorption zone facing side 62 of the separator plates 52 and to the adsorption zone contact portions 59.

The heat transfer layer 51 may include a heat transfer zone corrugated sheet 66, as depicted in FIG. 4. The heat transfer zone corrugated sheet 66 may be in contact with and extend between two separator plates 52. The heat transfer zone corrugated sheet 66 may comprise a plurality of heat transfer zone fins 67 and a plurality of heat transfer zone contact portions 68. The heat transfer zone fin 67 may be the portion of the heat transfer zone corrugated sheet 66 that is perpendicular to and extends between the separator plates 52. The heat transfer zone contact portion 68 may be the portion of the heat transfer corrugated sheet 66 that is parallel to and in contact with the separator plate 52.

The heat transfer zone fins 67 may be positioned about perpendicular to the separator plates 52 and may extend about parallel to the heat transfer flow line 56. The heat transfer zone fins 67 may direct the flow of heat transfer fluid 69 (see FIG. 2a) through the adsorption heat exchanger 40. The heat transfer zone fins 67 may increase the heat transfer efficiency of the adsorption heat exchanger 40. The heat transfer zone fin 67 may be in contact with and extend between two separator plates 52. For some applications the heat transfer zone fin 67 may have a heat transfer fin height 70 of between about 0.04 inches and about 0.2 inches. The heat transfer fin height 70 may vary with application and may depend on factors including the composition of the heat transfer zone fin 67 and the application. For example, for an automotive cooling system having heat transfer zone fins 67 comprising aluminum, the heat transfer fin height 70 may be about 0.050 inches. For some applications the heat transfer zone fin 67 may have a heat transfer fin thickness 71 of between about 0.003 inches and about 0.01 inches. The heat transfer fin thickness 71 may vary with application and may depend on factors including the composition of the heat transfer fluid 69 and the application.

The density of heat transfer zone fins (fins/inch) may vary with application and may depend on factors including the composition of the heat transfer fluid 69 and the desired volume of the heat transfer flow passage 55. The density of the heat transfer zone fins 67 may be defined as the number of fins per inch of the heat transfer layer width as measured perpendicular to the heat transfer flow line 56 and parallel to the separator plate 52. For some applications, the density of the heat transfer zone fins 67 may be between about 10 fins/inch and about 30 fins/inch.

The heat transfer zone contact portions 68 may be positioned about parallel to and in contact with the separator plates 52. The heat transfer zone contact portions 68 may be brazed to a heat transfer zone facing side 72 of the separator plates 52. For some applications the heat transfer zone contact portions 68 may have a heat transfer contact portion width 73 of between about 0.03 inches and about 0.1 inches. The heat transfer contact portion width 73 may vary and may depend on the desired density of the heat transfer zone fins 67. The heat transfer contact portion width 73 may be inversely proportion to the density of the heat transfer zone fins 67.

For some applications, in lieu of the heat transfer zone corrugated sheet 66, the heat transfer layer 51 may comprise a plurality of heat transfer zone fins 67 brazed directly to the separator plates 52.

The heat transfer layer 51 may include two heat transfer zone header bars 74, as depicted in FIG. 2a. The heat transfer zone header bars 74 may be positioned parallel to the heat transfer flow line 56. One heat transfer zone header bar 74 may be positioned at one side of the heat transfer layer 51 and the other heat transfer zone header bar 74 may be positioned at the opposing side of the heat transfer layer 51. The heat transfer zone header bars 74 may be brazed to the separator plates 52 and may provide structural support to the adsorption heat exchanger 40.

The heat transfer zone corrugated sheet 66, the heat transfer zone fin 67, the heat transfer zone contact portion 68 and heat transfer zone header bar 74 each may comprise a material, such as but not limited to, aluminized mylar, a polymer composite, or a metal. Useful metals may include aluminum, copper, titanium, brass, stainless steel, other light metals and alloys with high conductivity, and graphite fiber composite materials.

The separator plate 52 of the adsorption heat exchanger 40 may comprise a sheet material structure, as depicted in FIGS. 2a-c. The separator plate 52 may be positioned parallel to the layers 50, 51 (see FIGS. 3 and 4). One separator plate 52 may be positioned between and in contact with each adsorption layer/heat transfer layer pair. The separator plate 52 may prevent the flow of adsorbate 60 from entering the heat transfer layer 51 and prevent the flow of heat transfer fluid 69 from entering the adsorption layer 50. The separator plate 52 may comprise a material, such as but not limited to, aluminized mylar, a polymer composite, or a metal. Useful metals may include aluminum, copper, titanium, brass, stainless steel, other light metals and alloys with high conductivity, and graphite fiber composite materials. The width and length of the separator plate 52 may vary and may be about equal to the width and length of the layers 50, 51. For some applications, a separator plate thickness 75 may be between about 0.003 inches and about 0.1 inches. For example, for some applications the separator plate thickness 75 may be about 0.016 inches.

The adsorption heat exchanger 40 further may comprise two side plates 76, as depicted in FIG. 2a. The side plates 76 may be positioned parallel to the layers 50, 51. One side plate 76 may be positioned at one side of the adsorption heat exchanger 40 and the other side plate 76 may be positioned at the opposing side of the adsorption heat exchanger 40. The side plates 76 may comprise a material, such as but not limited to, aluminized mylar, a polymer composite, or a metal. For some applications, the side plates 76 may be brazed to and provide structural support for the adsorption heat exchanger 40.

A method 200 of generating a flow of adsorbate 60 is depicted in FIG. 5. The method 200 may comprise a step 210 of passing a flow of heat transfer fluid 69 through at least one heat transfer layer 51 of an adsorption heat exchanger 40 and a step 220 of transferring heat from the flow of heat transfer fluid 69 to an absorptive material coating 46 positioned within an adsorption layer 50 of the adsorption heat exchanger 40 such that an adsorbate vapor is desorbed from the adsorptive material coating 46. For some embodiments, as the adsorptive material coating 46 is heated the adsorbate vapor is desorbed from the adsorptive material coating 46 driving the flow of adsorbate 60 to move toward a condenser 42. For some applications, the flow of adsorbate 60 must comprise an adsorbable vapor such as but limited to, water, alcohols, ammonia, hydrocarbons, chloroflorocarbons, and mixtures thereof.

The step 210 may comprise passing the flow of heat transfer fluid 69 such that the flow of heat transfer fluid 69 is in contact with at least one heat transfer zone fin 67 of the absorption heat exchanger 40 and in contact with at least a portion of a heat transfer zone facing side 72 of the separator sheet 52. For some applications, the flow of heat transfer fluid 69 may comprise a liquid, such as but limited to, water, alcohols, ammonia, hydrocarbons, chloroflorocarbons, and mixtures thereof.

For some applications, the method 200 can use the adsorptive material coating 46 to reduce the partial pressure of the flow of adsorbate 60 (e.g. water or other working compound) in an adsorption loop 45 and thereby cause the adsorbate 60 to be evaporated from an evaporator 43. The liquid adsorbate 60 inside the evaporator 43 becomes cooler as it loses the corresponding heat of vaporization, while the adsorptive material coating 46 becomes hotter from the heat of adsorption. For some applications, the regeneration cycle may use a supply of hot water or air heated by waste heat from an engine exhaust to remove adsorbate 60 and regenerate the adsorptive material coating 46. Two adsorption heat exchangers 40 may be used in alternating cycles for some applications.

EXAMPLE 1

A plot of specific power (kW/kg) as a function of cycle time (sec.) is shown in FIG. 6. As it can be seen, high specific power can be achieved at a much shorter cycle time in comparison with current tube-plate design. Several fin densities (fpi) for the adsorption layer were considered. Wash coating process calls for optimum fpi number. An fpi number of more then 11 may not be suitable for some applications due to poor drainage of extra wash coat after its application onto the fin-plate structure.

EXAMPLE 2

The design parameters for one embodiment of the present invention are shown FIG. 7. In this example, the components (fins, plates, etc.) comprise aluminum. Dynamic simulation results of h for adsorption side (h=553/BTU/hr.ft².R) and fpi=11 were used for the adsorption heat exchanger design. The calculated design parameters for adsorption side (adsorption layer 50) and HT side (Ethylene Glycol/Water, (EGW) (heat transfer layer 51) are shown in FIG. 7. During the sorptive cooling process, adsorption/desorption side of adsorption heat exchanger was under a total pressure of 5-80 torr depending on the mode (i.e. adsorption or desorption). The geometry of an embodiment of the adsorption heat exchanger is shown on FIG. 8. The estimated adsorption heat exchanger core dry weight is 6.7 lb. As can be seen, embodiments of the present invention can increase adsorptive material surface area while reducing adsorption heat exchanger overall dimensions.

EXAMPLE 3

The sensitivity results on adsorption material coating thickness variations are shown in FIG. 9. The results show that specific power decreases when adsorption material coating thickness increases. Absolute cooling power increases with the increased adsorption material coating thickness. It should be noted here that adsorption side heat transfer coefficient would be slightly changed due to different adsorption material coating thickness, which was not considered in the sensitivity study.

EXAMPLE 4

The design and performance parameters for an adsorption heat exchanger according to nine embodiments of the present invention are shown in FIG. 10. For comparison, the design and performance parameters for a prior art plate-tube AHE are also shown. As can be seen, embodiments of the present invention can provide improved adsorption heat exchangers. When compared to the prior art plate-tube AHE, the adsorption heat exchangers of the present invention have higher specific power and lower cycle times.

For the prior art tube-plate AHE, heat transfer to adsorptive material occurs mainly by conductance in a chain of tube-tube/plate contact-plate-adsorptive material. The quality of tube-plate and adsorbent-plate contacts is extremely important in achieving high heat and mass transfer efficiency during adsorption/desorption cycles and, consequently, for their duration. Heat and mass transfer efficiency affect the specific power of heat exchanger.

The fin-plate design of the present invention can provide high surface area and enhance heat and mass transfer from the heat transfer fluid to the adsorbent material. This along with a thinner adsorbent layer (adsorptive material coating 46) can significantly reduce adsorption/desorption cycle time and increase the specific power of the adsorption heat exchanger 40 for some applications.

As can be appreciated by those skilled in the art, the present invention provides improved adsorption heat exchangers. Embodiments of the present invention provide heat exchangers having enhanced adsorption/desorption efficiency and high heat transfer efficiency. The increased adsorptive material surface area and improved heat transfer efficiency of the present invention can provide heat exchangers with reduced cycle time.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

1. An apparatus comprising:

at least one adsorption layer having an adsorption zone corrugated sheet, at least a portion of said adsorption zone corrugated sheet having an adsorptive material coating;

at least one heat transfer layer having a heat transfer zone corrugated sheet, said heat transfer layer positioned parallel to said adsorption layer; and

a separator plate positioned between and in contact with said adsorption zone corrugated sheet and said heat transfer zone corrugated sheet.

2. The apparatus of claim 1, wherein said adsorption zone corrugated sheet includes at least one adsorption zone fin, said adsorption zone fin having an adsorption fin height of between about 0.10 inches and about 0.5 inches.

3. The apparatus of claim 2, wherein said adsorption zone fin has an adsorption fin thickness of between about 0.001 inches and about 0.01 inches.

4. The apparatus of claim 1, wherein said adsorption zone corrugated sheet includes a plurality of adsorption zone fins, a density of said adsorption zone fins is between about 7 fins/inch and about 28 fins/inch.

5. The apparatus of claim 1, wherein said adsorption layer is oriented in a direction 90° of said heat transfer layer.

6. The apparatus of claim 1, wherein said adsorptive material coating has an adsorptive coating thickness of between about 0.004 inches and about 0.040 inches.

7. The apparatus of claim 1, wherein said adsorption zone corrugated sheet includes at least one adsorption zone contact portion positioned parallel to and in contact with said separator plate.

8. The apparatus of claim 1, wherein at least a portion of said separator plate has an adsorptive material coating.

9. The apparatus of claim 1, wherein said separator plate has a separator plate thickness between about 0.003 inches and about 0.1 inches.

10. The apparatus of claim 1, wherein said heat transfer zone corrugated sheet includes at least one heat transfer zone fin, said heat transfer zone fin having a heat transfer fin height of between about 0.04 inches and about 0.2 inches.

11. An apparatus comprising:

an adsorption zone corrugated sheet having a plurality of adsorption zone fins and a plurality of adsorption zone contact portions;

a heat transfer zone corrugated sheet positioned parallel to and oriented 90° of said adsorption zone corrugated sheet;

a separator sheet having an adsorption zone facing side and a heat transfer zone facing side, said separator sheet positioned between and in contact with said adsorption zone corrugated sheet and said heat transfer corrugated sheet; and

an adsorptive material coating in contact with at least one adsorption zone fin.

12. The apparatus of claim 11, wherein said adsorptive material coating is in contact with at least a portion of said adsorption zone facing side.

13. The apparatus of claim 11, wherein said adsorptive material coating is in contact with at least one adsorption zone contact portion.

14. The apparatus of claim 11, wherein said adsorptive material coating comprises at least one of silica gel, aluminas, silicas, zeolites, activated carbon, metal chlorides, metal hydrides, supported Na2SO4, synthetic polymers, or mixtures thereof.

15. The apparatus of claim 11, wherein said heat transfer zone corrugated sheet has a plurality of heat transfer zone fins, a density of said heat transfer zone fins is between about 10 fins/inch and about 30 fins/inch.

16. The apparatus of claim 11, wherein said adsorptive material coating has an adsorptive coating thickness of less than about 0.5 mm.

17. An apparatus comprising:

a plurality of adsorption layers;

a plurality of heat transfer layers, said plurality of adsorption layers and said plurality of heat transfer layers positioned such that a stacked arrangement of alternating adsorption layers and heat transfer layers is formed, said plurality of adsorption layers and said plurality of heat transfer layers forming at least one adsorption layer/heat transfer layer pair; and

a separator plate positioned between and in contact with said adsorption layer/heat transfer layer pair.

18. The apparatus of claim 17, wherein at least one adsorption layer includes two adsorption zone header bars positioned parallel to an adsorption flow line of said adsorption layer and positioned such that one adsorption zone header bar is at one side of said adsorption layer and the other adsorption zone header bar is at the opposing side of said adsorption layer.

19. The apparatus of claim 17, wherein at least one said adsorption layer has an adsorptive coating thickness of between about 0.004 inches and about 0.04 inches.

20. The apparatus of claim 17, further comprising at least one side plate positioned parallel to said plurality of adsorption layers and positioned at a side of said stacked arrangement of alternating adsorption layers and heat transfer layers.