JP3634114B2 - Method of manufacturing adsorbent for molding, adsorption heat exchanger with integral molding structure using the same, and method of manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an adsorbent for an adsorption refrigerator and an adsorption heat exchanger for storing the adsorbent, and in particular, an adsorbent for molding that can be integrally formed with a heat transfer binder with improved adsorption / desorption characteristics, and the adsorbent The present invention relates to a heat exchanger having an integrally formed structure.
[0002]
[Prior art]
An adsorption refrigerator is a refrigerator that generates heat using a heat source as a heat source, utilizing the endothermic phenomenon associated with a reversible reaction between a solid adsorbent, such as silica gel, and water as a refrigerant. The process consists of two solid adsorbent heat exchangers (hereinafter referred to as adsorption heat exchangers). FIG. 7 shows a schematic configuration of a conventional adsorption refrigerator.
[0003]
For example, as shown in FIG. 7, when the regeneration process is performed by the adsorption heat exchanger 50 and the adsorption process is performed by the adsorption heat exchanger 51, the black mark switching valve and the steam valve are closed and the white mark switching valve is closed. And open the steam valve.
In this case, when the regeneration warm water 71 is introduced and heated via the switching valve 61 to the adsorption heat exchanger 50 in the vacuum vessel, the water vapor desorbed from the built-in adsorbent is released to the condenser 52 via the steam valve 56. . In the condenser 52, the discharged water vapor is liquefied by the cooling water 72 for condensation. The condensed and dripped water is stored in the lower part of the evaporator 53, and the regeneration of the adsorbent incorporated in the adsorption heat exchanger 50 is completed.
[0004]
On the other hand, the adsorption cooling water 73 is introduced into the adsorption heat exchanger 51 in another vacuum vessel via the switching valve 63, and the adsorbent contained therein is cooled and shifts to an adsorbable state. Further, water vapor generated in the evaporator 53 via the pump 53a and the sprayer 53b is sent to the adsorption heat exchanger 51 via the steam valve 57 and is adsorbed by the adsorbent in the adsorbable state. At this time, in the evaporator 53, the water vapor generated through the sprayer 53b takes the latent heat of evaporation from the fluid 60 to be cooled in the process of generation. As a result, cold water can be produced.
That is, the adsorbent built in the adsorption heat exchanger 51 is placed in the adsorption process, and the evaporator 53 supplies cold heat to the fluid 60 to be cooled.
[0005]
When the water vapor adsorption and desorption amount approaches saturation, the switching valve 61 is switched to 62, 65 is switched to 67, 63 is switched to 64, and 68 is switched to 66. As a result, the adsorption heat exchanger 50 adsorbs water vapor. The water vapor is desorbed by the adsorption heat exchanger 51, and the switching operation is repeated thereafter.
[0006]
The structure of the adsorption heat exchangers 50 and 51 is shown in FIGS. 8 (A) and 8 (B). FIG. 8A shows a schematic diagram of a heat exchanger having a plate-type heat conducting member. (Japanese Patent Application No. 3-83361)
As the adsorbent, activated carbon, alumina, activated alumina, and silica gel are conceivable, but silica gel is used because exhaust heat at 60 to 80 ° C. can be used effectively and is relatively easy to obtain.
As shown in FIG. 8 (A), the adsorption heat exchanger is filled with, for example, particulate adsorbent (silica gel) 76 on both sides of a heat transfer member 75 that forms a passage of warm water for regeneration or cooling water for adsorption. What is covered with a wire mesh 79 for pressing the adsorbent is used as a set of 10 or more sheets.
The thickness Y of the adsorbent packed bed is determined in consideration of heat transfer and mass transfer.
In addition to the above structure, as shown in FIG. 8 (B), a heat transfer rod 77 which is a heat transfer member for forming the passage of the hot water and the cooling water, and a number of them provided at right angles and at equal intervals to the heat transfer rod. It is formed of a plurality of fins 78, and is filled with an adsorbent 76 so as to surround the outer periphery of the heat transfer rod 77 from the outside of the fins through a gap between the fins, and is covered with a metal mesh 79 or the like from the outside. (Japanese Patent Application No. 4-159308)
[0007]
In any of the above structures, since the adsorbents 76 and the adsorbent 76 and the surface of the fin 78 or the heat transfer member 75 are formed by point contact, the heat transfer from the heat transfer member to the adsorbent is It is in a situation where there is no choice but to rely on conduction between solids with poor thermal conductivity and conduction of heat between solid gases.
As a result, in the adsorption heat exchanger, the heat transfer performance is poor, the preheating and heat supply accompanying the adsorption and desorption of water vapor is insufficient, the adsorption / desorption rate is lowered, and the adsorbent that fully exhibits the adsorption / desorption function is limited. And formed a factor that led to the expansion of the device.
[0008]
In order to solve these problems, various proposals have been made conventionally. Proposal a in Japanese Patent Laid-Open No. 4-143558, Proposal b in Japanese Patent Laid-Open No. 8-200586, Proposal c in Japanese Patent Laid-Open No. 8-270855. It is disclosed.
In the proposal a, a mixed slurry is formed by an adsorbent and a metal promoter, the slurry and the heat transfer member are put into a mold, and the mixture of the adsorbent and the metal promoter is integrally fired on the heat transfer member. It is configured to form and
Proposal b is characterized in that the surface of the heat transfer member and the silica gel are integrated by coating or embedding by applying and fixing powdery silica gel containing a dehydrating adhesive on the surface of the heat transfer member. Is,
Proposal c is characterized in that a heat conductive layer portion is provided between the heat transfer member surface and the adsorbent.
[0009]
To see the conventional proposals ranging from the above proposal a to proposal c,
In proposal a, a mixture of adsorbent and metal promoter is formed, and the mixture and the heat transfer member are integrated by sintering. In this case, the heat transfer coefficient can be improved by mixing the metal promoter, but a dense polycrystalline body is formed in the mixture because the sintering means is used to bond the mixture and the heat transfer member. Therefore, mass transfer during adsorption / desorption of the refrigerant becomes difficult, and adsorption / desorption is limited only to the adsorbent on the surface, and a reduction in efficiency is inevitable.
Next, in Proposal b, a mixture is formed by adsorbent and dehydrating adhesion to form a slurry, and the slurry is applied to a heat transfer member, coated or embedded, and dried and integrated. Therefore, the contact area between the heat transfer member and the adhesive, and between the adhesives is expanded compared to the conventional point contact, but no consideration is given to the thermal conductivity of the adhesive itself. There is no great expectation for improvement in performance, and no consideration is given to mass transfer from outside the refrigerant.
In Proposal c, a heat conduction layer is provided on the surface of the heat transfer member, and the particulate adsorbent is filled through the heat conduction layer, so that heat conduction between the adsorbent and the heat transfer member is performed. Is improved by increasing the contact area compared to the conventional point contact, but the heat transfer between the adsorbents is not improved.
[0010]
[Problems to be solved by the invention]
By the way, the heat transfer performance U of the adsorption heat exchanger, the effective thermal conductivity λ _eff of the adsorbent layer, the adsorbent layer thickness S _ad , the heat transfer coefficient h _{w on} the heat transfer member surface, and the transfer member thickness S _w The following relational expression holds between the heat conductivity λ _w and the heat transfer coefficient h _ext of the heat medium (refrigerant).
1 / U = 1 / h _w + S _w / λ _w + S _ad / λ _eff + 1 / h _ext
Therefore, in the above equation, the heat transfer performance U can be improved by improving the effective heat conductivity λ _eff of the adsorbent layer and the heat transfer coefficient h _{w on} the surface of the heat transfer member.
[0011]
The present invention has been made in view of the above problems,
While improving the effective thermal conductivity λ _eff of the adsorbent layer and improving the heat transfer coefficient of the heat transfer member surface that forms the passage of hot water or cooling water for adsorption / desorption, the adsorbent adsorption performance may be impaired. It is an object of the present invention to provide an adsorption heat exchanger having a single structure using the adsorbent for molding without using the adsorbent and the adsorbent.
[0012]
[Means for Solving the Problems]
The gist of the present invention will be described below.
That is, in order to improve the effective thermal conductivity λ _eff of the adsorbent layer, graphite powder is mixed with granular silica gel in order to fill each gap of the granular silica gel group and the gap between the heat transfer surfaces with a high thermal conductive agent. Thus, a high heat conduction adsorbent is formed.
Then in order to improve the heat transfer rate h _w in the heat transfer member surface, and rich in plasticity due to the formation of solid polymeric network of possible molded and swell stretching high thermal conductivity adsorbent the mixture to the heat transfer member In order to make it possible to form a strong molding surface, an adsorbent cellulose organic binder is additionally mixed and then formed into a dispersed slurry in water.
Furthermore, the addition of the porous inorganic binder facilitates the mass transfer of the refrigerant from the outside.
[0013]
The blending ratio of the cellulose organic binder to the porous inorganic binder is based on the premise that the adsorption performance as an adsorbent is not impaired, and in particular, consideration must be given to avoiding the blocking of macropores and mesopores of silica gel.
In addition, the pore volume and the specific surface area must be increased in order to maintain a large adsorption capacity even under a low relative pressure.
[0014]
In addition, the heat transfer member is dip-molded in a solution obtained by dispersing a powdered granular product based on the above blend ratio into a mixed slurry or paste, or after paste processing, mold forming, air drying and heat drying, An adsorption heat exchanger is formed.
[0015]
Therefore, the invention of claim 1
In the method for producing an adsorbent for adsorption type refrigerator, after mixing graphite powder with granular silica gel to form a high thermal conductivity adsorbent, an adsorbent cellulose organic binder is additionally mixed and then dispersed in water, Further, the production of an adsorbent for molding characterized in that a slurry or paste formed by adding a porous inorganic binder is dried by low-temperature drying at about 70 ° C. while maintaining air drying and saturated steam. Is in the way .
[0016]
The invention according to claim 2 is characterized in that graphite powder is mixed with granular silica gel to form a high thermal conductive adsorbent, adsorbent cellulose organic binder is additionally mixed and then dispersed in water, The adsorbent for molding formed into a slurry by adding a porous inorganic binder is immersed in a heat transfer pipe and heat transfer fin, and dried by low temperature drying at about 70 ° C. while maintaining air drying and saturated steam. It is a manufacturing method of the adsorption heat exchanger of the integral molding structure characterized by making the agent dip-molding.
[0017]
Further, in the invention of claim 3, after the graphite powder is mixed with the granular silica gel to form a high thermal conductive adsorbent, an adsorbent cellulose organic binder is additionally mixed and dispersed in water, After the adsorbent formed in the paste form by the addition of the porous inorganic binder is filled into the heat transfer pipe and the heat transfer fin in the paste form, it is air-dried in a state where the filling processed part is sandwiched between the porous plates provided with grooves. A method for producing an adsorption heat exchanger having an integrally formed structure, wherein the adsorbent is subjected to immersion molding by low-temperature drying at about 70 ° C. while maintaining saturated steam .
[0018]
According to a fourth aspect of the present invention, there are provided a plurality of heat transfer rods forming passages for hot water or cooling water, and a plurality of flat fins that intersect at right angles to the heat transfer rods and are provided at equal intervals and in parallel. A mold forming adsorbent layer formed by paste processing between the fins and a mold, and a groove formed in the middle of the mold forming adsorbent layer, wherein the mold adsorbent layer is formed of silica gel . It is an adsorption heat exchanger characterized by comprising graphite, a cellulose organic binder, and a porous inorganic binder .
[0019]
[Action]
The effective thermal conductivity of the adsorbent layer can be improved due to the high thermal conductivity of the graphite by blending the graphite according to claim 1,
In addition, by blending an appropriate amount of cellulose organic binder, it is possible to expect the adsorption function for water vapor and to maintain the strength of the molding surface that is strong and has high plasticity due to the polymer network capable of swelling and stretching.
Moreover, the effect of facilitating mass transfer of the refrigerant vapor in the adsorbent layer can be expected by blending an appropriate amount of the porous inorganic binder.
In addition, by immersing the heat transfer material in the adsorbent for molding or by air-drying after paste processing and by low-temperature drying at about 70 ° C., drying is performed while maintaining saturated steam, thereby preventing cracks on the molding surface. .
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention unless otherwise specified. Absent.
FIG. 1 is a perspective view showing a schematic configuration of an adsorption heat exchanger formed by dip molding using the molding adsorbent of the present invention, and FIG. 2 is a mold using the molding adsorbent. It is a perspective view which shows the general | schematic structure of the adsorption heat exchanger shape | molded and made into the integral structure.
[0021]
As shown in FIG. 1, the adsorption heat exchanger 15 a having an integral structure formed by immersion includes a heat transfer rod 10 made of a plurality of copper forming a passage for hot water or cooling water, and a cross at right angles to the heat transfer rod 10. A plurality of flat fins 11 made of a plurality of aluminum, aluminum alloy, copper, copper alloy and the like provided at equal intervals and in parallel, and a dip-molded dip-molded adsorbent layer 14 covering the fins 11 and the heat transfer rod 10 Constitute.
[0022]
The immersion molding adsorbent layer 14 is made of a molding adsorbent formed in the form of a slurry, and an example of the adjustment method and processing conditions are shown below.
80.8 parts by weight of silica gel powder of 42 mesh or less, 9.0 parts by weight of graphite fine particles, 3.55 parts by weight of cellulose organic binder and 6.63 parts by weight of powdery or fibrous inorganic binder with zepiolite are mixed for 15 minutes, 55.6 weights Part of water is added and dispersed and mixed for 60 minutes to form a slurry solution.
1 is immersed in the above-mentioned solution and air-dried by standing in the atmosphere for 2 days after the immersion, followed by a drying process at approximately 70 ° C. for 36 hours. As a result, the adsorption heat exchanger 15a having an integral structure is formed by forming the immersion molded adsorbent layer 14 shown in FIG.
[0023]
FIG. 2 shows a schematic configuration of an adsorption heat exchanger 15b that is molded by using a molding adsorbent to form an integral structure.
The integrally formed adsorption heat exchanger 15b by molding is provided with a plurality of copper heat transfer rods 10 forming a passage of hot water or cooling water, and intersecting the heat transfer rods 10 at right angles and at equal intervals and in parallel. A plurality of flattened fins 11 made of a plurality of aluminum, aluminum alloy, copper, copper alloy, and the like, a mold adsorbent layer 12 paste-molded between the fins, and the mold adsorption The groove 13 is formed before and after the middle of the agent layer 12.
[0024]
The mold forming adsorbent layer 12 is composed of a forming adsorbent formed in a paste form, and an example of the adjustment method and processing conditions are shown below.
86.2 parts by weight of silica gel powder having a mesh size of 42 mesh or less, 4.35 parts by weight of graphite fine particles, 4.35 parts by weight of cellulose organic binder, and 5.08 parts by weight of inorganic inorganic binder of zepiolite are mixed for 15 minutes to obtain 39.6 parts by weight. Water is added and dispersed and mixed for 60 minutes to form a paste.
Next, paste processing is performed on the heat transfer member composed of the heat transfer rod 10 and the fins 11 shown in FIG. 2 with the above-mentioned paste-like adsorbent, and then sandwiched between Teflon and stainless steel perforated plates and left to stand in the atmosphere for 3 days. After performing the drying process at approximately 70 ° C. for 36 hours, the adsorption heat exchanger 15b having the integral structure is formed by forming the molded adsorbent layer 12 shown in FIG.
In addition, the upper and lower grooves 13 in FIG. 2 are formed at the same time as the sandwiching press with the perforated plate having a grooved shape.
[0025]
Among the mixing members constituting the molding adsorbent that forms the immersion molding adsorbent layer and mold molding adsorbent layer,
Graphite is a high thermal conductivity member and is used to improve the effective thermal conductivity λ _eff of the adhesive layer.
The cellulose organic binder makes it possible to form a strong and plastically shaped molding surface and maintain its strength by adsorbing water vapor and a polymer network capable of swelling and stretching.
Moreover, the effect of facilitating mass transfer of the refrigerant vapor in the adsorbent layer can be expected by blending an appropriate amount of the porous inorganic binder.
Further, the heat transfer body is dipped in the molding adsorbent or dried by air drying after paste processing and low-temperature drying at about 70 ° C., and drying is performed while maintaining saturated steam, thereby preventing cracks on the molding surface.
Note that the organic binder does not impair the adsorption performance of the silica gel as an adsorbent, and is expected to have a large adsorption capacity under a low relative pressure in consideration of avoidance of clogging of silica gel macropores and mesopores. Consideration is given to increase the pore volume and specific surface area as much as possible.
[0026]
Molded product No. 1 provided with the above-mentioned immersion molded adsorbent layer 14 and mold molded adsorbent layer 12. Comparative measurement of heat transfer characteristics and adsorption characteristics was performed on the conventional silica gel crushing mold 1 and the molded product B.
As a result, heat transfer performance U is molded adsorbent in the desorption initial 62.2W / m ₂ K, molding adsorbent in crushing the silica gel 44.8W / m ₂ K, also during the desorption period 61.5W / m ₂ K and crushed silica gel were 25.9 W / m ₂ K.
[0027]
As shown in the above results, high heat transfer performance can be obtained, the regeneration temperature is increased, the adsorption temperature is decreased, and the cycle refrigerant circulation rate can be increased. Adsorption characteristics for 1 and crushed silica gel are shown.
Further, the adsorption and regeneration cycle time can be shortened based on the above result. In addition, downsizing can be achieved.
The reason why the groove 13 is provided in the molded adsorbent layer 12 is to facilitate the mass transfer of the refrigerant, thereby enabling the cycle time of the molded product B to be reduced.
[0028]
FIG. 5 is a schematic diagram showing a schematic configuration of a solar-driven adsorption heat exchanger using the molding adsorbent of the present invention.
As shown in the figure, the solar-powered adsorption heat exchanger 16 of the present invention has a molded adsorbent 20, a heat insulating container 21 for storing the adsorbent, and a pressure-resistant heat-resistant sealed structure provided at the top of the heat insulating container. The light transmissive member 25 such as glass, and the sunlight irradiation space / adsorption / desorption space 22 formed by the pressure resistance, heat resistance, and airtight structure, as shown in FIG. In the daytime, as shown in FIG. 6 (A), in the solar heat-driven adsorption heat exchanger 16, the adsorbent is heated and desorbed and regenerated, and the generated refrigerant vapor (water vapor) 24 is introduced into the condenser 17 and condensed. Condensation takes place with the cooling water.
On the other hand, as shown in FIG. 6B, radiation cooling is performed at night, and the adsorbent is cooled to increase the adsorption capacity of the adsorbent. Here, by operating the condenser 17 as an evaporator, evaporation in the evaporator is performed, and the generated water vapor 24 is adsorbed by the adsorbent, and cold heat is generated in the evaporation process of the evaporator.
The solar-driven adsorption heat exchanger having the above functions is required to operate sufficiently at ambient temperature. In this regard, when the molding adsorbent of the present invention using black graphite is used, the expected effect is large. There is something to be.
[0029]
【The invention's effect】
The heat transfer performance can be improved by the structure of the above-mentioned molded adsorbent, and the structure of the adsorption heat exchanger using this adhesive can increase the regeneration temperature and decrease the adsorption temperature. Increases the amount of circulation and improves refrigeration capacity.
Further, the adsorption regeneration cycle time can be shortened, and the heat exchanger can be made compact.
Also in the solar-driven adsorption heat exchanger, the efficiency can be increased by using the molding adsorbent of the present invention.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of an adsorption heat exchanger formed by dip molding using an adsorbent for molding according to the present invention to form an integral structure.
FIG. 2 is a perspective view showing a schematic configuration of an adsorption heat exchanger that is molded by using the molding adsorbent of the present invention to form an integral structure.
FIG. 3 is a graph showing the adsorption characteristics of an adsorption heat exchanger when the molding adsorbent of the present invention is used.
FIG. 4 is a diagram showing the adsorption characteristics of an adsorption heat exchanger using conventional crushed silica gel.
FIG. 5 is a diagram showing a schematic configuration of a solar-powered adsorption heat exchanger using the molding adsorbent of the present invention.
FIGS. 6A and 6B are schematic diagrams showing an operating state of an adsorption heat exchanger for driving solar light, where FIG. 6A shows an operating state in the daytime, and FIG. 6B shows an operating state in the nighttime.
FIG. 7 is a diagram showing a schematic configuration of a conventional adsorption refrigerator.
8A and 8B are diagrams showing a schematic configuration of a conventional adsorption heat exchanger, in which FIG. 8A shows a plate heat conduction type, and FIG. 8B shows a pipe and fin heat conduction type.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Heat transfer rod 11 Fin 12 Mold shaping | molding adsorbent layer 13 Groove 14 Immersion shaping | molding adsorption agent layers 15a and 15b Adsorption heat exchanger 16 of a monolithic structure Adsorption heat exchanger 17 for solar drive 17 Condenser 20 Molding adsorption agent 21 Thermal insulation container 22 Sunlight irradiation space and adsorption / desorption space

Claims (4)

In the method for producing an adsorbent for adsorption type refrigerator, after mixing graphite powder with granular silica gel to form a high thermal conductivity adsorbent, an adsorbent cellulose organic binder is additionally mixed and then dispersed in water, Further, the production of an adsorbent for molding characterized in that a slurry or paste formed by adding a porous inorganic binder is dried by low-temperature drying at about 70 ° C. while maintaining air drying and saturated steam. Way . After mixing graphite powder with powdered silica gel to form a high thermal conductivity adsorbent, an adsorbent cellulose organic binder is added and dispersed in water, and then added into a slurry by adding a porous inorganic binder. The adsorbent formed by dipping the adsorbent for molding formed in a heat transfer pipe and a heat transfer fin by low temperature drying at about 70 ° C. while maintaining air drying and saturated steam. A method for manufacturing an adsorption heat exchanger having an integrally formed structure. After mixing graphite powder with powdered silica gel to form a high thermal conductivity adsorbent, an adsorbent cellulose organic binder is added and dispersed in water, and then added into a paste by adding a porous inorganic binder. After filling the formed adsorbent into a heat transfer pipe and heat transfer fin in a paste form, the air-dried and saturated steam is maintained at about 70 ° C. with the filled portion sandwiched between perforated plates provided with grooves. A method for producing an adsorption heat exchanger having an integrally formed structure, wherein the adsorbent is immersed and molded by low-temperature drying . A plurality of heat transfer rods forming a passage of hot water or cooling water, a plurality of flat fins that intersect perpendicularly to the heat transfer rods and are provided at equal intervals and in parallel, and a paste between the fins A molded adsorbent layer that has been processed and molded, and a groove formed in the middle of the molded adsorbent layer, the mold adsorbent layer being silica gel, graphite, cellulose organic binder, and porosity An adsorption heat exchanger comprising an inorganic binder .

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