Title: Adsorption refrigerating device
Abstract: An adsorption refrigeration device comprising an evaporator chamber containing a refrigerant liquid that evaporates under the effect of a depression, a connecting device and an adsorption chamber containing an adsorbent capable of fixing the vapors of the refrigerant liquid, wherein the adsorbent is constituted by one or more rigid blocks comprising a plurality of cavities, at least one part of said cavities being feeder cavities capable of diffusing vapors of refrigerant liquid on the adsorbent.
Patent Number: 7,000,426 Issued on 02/21/2006 to Jeuch
| Inventors:
|
Jeuch; Pierre (Saint-Aubin, FR)
|
| Assignee:
|
Thermagen (S.A.) (Gif-sur-Yvette, FR)
|
| Appl. No.:
|
239822 |
| Filed:
|
July 6, 2001 |
| PCT Filed:
|
July 6, 2001
|
| PCT NO:
|
PCT/EP01/09028
|
| 371 Date:
|
February 20, 2003
|
| 102(e) Date:
|
February 20, 2003
|
| PCT PUB.NO.:
|
WO02/02998 |
| PCT PUB. Date:
|
January 10, 2002 |
Foreign Application Priority Data
| Jul 06, 2000[FR] | 00 08835 |
| Nov 13, 2000[FR] | 00 14559 |
| Current U.S. Class: |
62/480; 62/481; 252/69 |
| Current Intern'l Class: |
F25B 17/08 (20060101); F25B 17/00 (20060101) |
| Field of Search: |
62/480,481,477,478,101,106
165/104.12
252/69
502/400
264/122
|
References Cited [Referenced By]
U.S. Patent Documents
| 3579464 | May., 1971 | Rosen et al.
| |
| 4144171 | Mar., 1979 | Krause.
| |
| 4220553 | Sep., 1980 | Krause.
| |
| 4367079 | Jan., 1983 | Wallsten.
| |
| 4581049 | Apr., 1986 | Januschkowetz.
| |
| 4637218 | Jan., 1987 | Tchernev.
| |
| 4674563 | Jun., 1987 | Maier-Laxhuber et al.
| |
| 4759191 | Jul., 1988 | Thomas et al.
| |
| 4928495 | May., 1990 | Siegel.
| |
| 5335519 | Aug., 1994 | Bernier.
| |
| 5482906 | Jan., 1996 | Sakai et al.
| |
| 5661986 | Sep., 1997 | Labranque.
| |
| 5768908 | Jun., 1998 | Tanaka et al.
| |
| 2004/0035145 | Feb., 2004 | Jeuch.
| |
| Foreign Patent Documents |
| 94 04 126.1 | Aug., 1994 | DE.
| |
| 197 30 697 | Jan., 1999 | DE.
| |
| 198 18 807 | Oct., 1999 | DE.
| |
| 948 292 | Jul., 1949 | FR.
| |
| 1 029 877 | Jun., 1953 | FR.
| |
| 2 679 633 | Jan., 1993 | FR.
| |
| WO 99/4996/4 | Oct., 1999 | WO.
| |
| WO 00/3120/6 | Jun., 2000 | WO.
| |
Primary Examiner: Jiang; Chen Wen
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. An adsorption refrigeration device comprising an evaporator chamber containing
a refrigerant liquid with its vapor that evaporates under the effect of a depression,
a connecting device and an adsorption chamber under vacuum containing an adsorbent
capable of fixing the vapors of the refrigerant liquid, wherein the adsorbent comprises
one or more rigid blocks comprising a plurality of cavities, at least one part
of said cavities being feeder cavities capable of diffusing vapors of refrigerant
liquid on the adsorbent.
2. A refrigeration device according to claim 1, wherein at least one other cavity
is a heat-exchange cavity capable of discharging the heat released during the adsorption
of the vapors of the refrigerant liquid.
3. A refrigeration device according to claim 2, wherein the block has two zones
separated by a thermally conductive vacuum-tight sheathing, the first zone comprising
the adsorbent and the feeder cavities and opening on one face of the block in the
adsorption chamber, and the second zone comprising the at least one heat-exchange
cavity and opening on the opposite face of the block on the outside of the adsorption chamber.
4. A refrigeration device according to claim 3, wherein the sheathing comprises
at least one metal tube that sheathes the at least one heat-exchange cavity.
5. A refrigeration device according to claim 3, wherein the first zone comprises
metallic ribs thermally bonded to the sheathing.
6. A refrigeration device according to claim 5, wherein the ribs are in aluminum.
7. A refrigeration device according to claim 3, wherein the sheathing comprises
a plastic film resting on the walls of the second zone of the block and bonded
to the adsorption chamber.
8. A refrigeration device according to claim 3, wherein the second zone of the
adsorbent block comprises a vapor diffusion device.
9. A refrigeration device according to claim 8, wherein the vapor diffusion device
consists of a hydrophobic porous material.
10. A refrigeration device according to claim 3, wherein the second zone of the
block comprises a lid with at least one aperture to the outside atmosphere that
limits the flow rate of a vapor of a phase changing material.
11. A refrigeration device according to claim 10, wherein the vapor of the phase
changing material undergoes adiabatic expansion through said at least one aperture
so as to lower the temperature when it escapes outwards.
12. A refrigeration device according to claim 11, wherein the lowering of the
temperature of the vapor is greater than or equal to 35° C.
13. A refrigeration device according to claim 2, wherein the at least one heat-exchange
cavity contains a heat sink constituted by a phase-changing material.
14. A refrigeration device according to claim 13, wherein the phase-changing
material passes from the solid state to the liquid state.
15. A refrigeration device according to claim 13, wherein the phase-changing
material passes from the liquid state to the gas state.
16. A refrigeration device according to claim 15, wherein the material is water.
17. A refrigeration device according to claim 15, wherein the phase-changing
material comprises an aromatic additive.
18. A refrigeration device according to claim 2, with cyclical operation, comprising
an adsorption phase and an adsorbent regeneration phase, the at least one heat-exchange
cavity capable of heating the adsorbents for their regeneration.
19. A refrigeration device according to claim 18, wherein the at least one heat-exchange
cavity contains a heat-carrying fluid comprises of a liquid-gas phase-changing material.
20. A refrigeration device according to claim 19, wherein the boiling temperature
of the heat-carrying fluid is different in the two distinct phases of adsorption
and regeneration.
21. A refrigeration device according to claim 20, wherein the boiling temperature
of the heat-carrying fluid is regulated by the pressure of the fluid flowing in
the thermal circuit in contact with the domes.
22. A refrigeration device according to claim 18, wherein the at least one heat-exchange
cavity is closed by a dome whose external surface is in contact with a fluid flowing
in a thermal circuit.
23. A refrigeration device according to claim 18, wherein the at least one heat-exchange
cavity comprises at least one tube for the supply of heat-carrying fluid.
24. A device according to claim 1, wherein the adsorbent is a zeolite.
25. A device according to claim 1, wherein the refrigerant liquid is water and/or
an alcohol.
26. A device according to claim 1, wherein the block further comprises thermal
insulation on its periphery.
27. A device according to claim 26, wherein the thermal insulation comprises
a mixture of adsorbent and resin.
28. A device according to claim 1, for single use.
29. A method of shaping an adsorbent block for use in a refrigeration device,
wherein the method comprises:
mixing an adsorbent material with a binder to obtain a paste;
shaping the paste to a block with cavities shaped within the block; and
drying the shaped block.
30. The method according to claim 29, wherein shaping the paste comprises an
injection molding step in a mold provided with the cavities' shapes.
31. The method according to claim 29, wherein shaping the paste comprises an
extrusion step through a die provided with the cavities' shapes and a cutting step.
32. The method according to claim 29, wherein the method further comprises creating
a thermally conductive vacuum-tight sheathing in the shaped block.
33. A method for manufacturing an adsorption refrigeration device comprising
an evaporator chamber containing a refrigerant liquid with its vapor that evaporates
under the effect of a depression, a connecting device and an adsorption chamber
under vacuum containing an adsorbent capable of fixing the vapors of the refrigerant
liquid, wherein the adsorbent comprises one or more rigid blocks comprising a plurality
of cavities, at least one part of said cavities being feeder cavities capable of
diffusing vapors of refrigerant liquid on the adsorbent, wherein the method further comprises:
shaping at least one adsorbent block, wherein shaping an adsorbent block comprises:
mixing an adsorbent material with a binder to obtain a paste;
shaping the paste to a block with cavities shaped in the block; and
drying the shaped block;
placing the shaped block in the adsorption chamber; and
providing the connecting device between the adsorption chamber and the evaporator chamber.
34. The method according to claim 33, wherein at least one cavity of the adsorbent
block being a heat-exchange cavity, and the method further comprises filling the
heat-exchange cavity with phase changing material.
35. The method according to claim 34, wherein the method further comprises providing
a diffusing device on one face of the adsorbent block where the heat-exchange cavity opens.
36. The method according to claim 34, wherein the method further comprises providing
a lid on one face of the adsorbent block where the heat-exchange cavity opens,
the lid comprising at least one hole adapted to provide for an adiabatic expansion
of vapor of the phase changing material.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for refrigeration by evaporation and
adsorption, whose principle consists in evaporating a liquid under the effect of
a depression sustained by adsorption of the vapors of said liquid. It is the evaporation
of this refrigerant liquid contained in an evaporator (a chamber, cavity or the
like) that prompts a cooling in the vicinity of the evaporator. Another chamber,
containing adsorbent material, is generally connected to the evaporator.
2. Description of the Prior Art
The principle of refrigeration by evaporation of a refrigerant liquid and adsorption
of vapor of this liquid has undergone numerous developments, both for cyclical
systems (with regeneration of adsorbents by heating) and for single-use systems.
In all these devices, the adsorption is accompanied by heat dissipation in the
adsorbent leading to a rise in temperature which it is sought to limit by discharging
a part of this heat.
The cyclical devices generally comprise adsorbents in connexion with heat exchangers
which firstly discharge the heat dissipated by the adsorbents during the adsorption
reaction of the refrigerant liquid vapors and secondly heat these adsorbents to
regenerate them.
The principle of cyclical adsorption for refrigeration is described in the U.S.
Pat. No. 4,637,218.
In the cyclical systems, a refrigerant liquid is evaporated by adsorption and
then condensed, the adsorbents being regenerated by heating after having fulfilled
their adsorption function. Heat exchangers are designed firstly to cool the adsorbents
during their function of adsorption and secondly to heat these adsorbents for their regeneration.
One of the main difficulties of the cyclical devices lies in the efficiency of
the heat coupling between the heat exchangers and the adsorbents. For example,
efficient thermal coupling is difficult to achieve with zeolites which are very
efficient adsorbents otherwise. Indeed, the adsorbents usually take the form of
grains or rods having very poor heat conductivity. The result thereof is low efficiency
of cyclical systems.
The U.S. Pat. No. 5,535,817 has efficiently analyzed these difficulties and proposes
a method for forming zeolites by deposition on a metal surface giving greatly enhanced
performance. The zeolites are directly deposited on the interior surface of metal
tubes so as to form an internal lining. The method of deposition proposed in this
patent is however complicated to implement. This makes it difficult to apply in
the case of low-cost, large-scale production.
In the case of single-use devices, the U.S. Pat. No. 4,759,191 proposes to limit
the rise in temperature by the addition to the adsorbents of different materials,
especially materials having a solid-liquid phase change between 30° C. and
70° C. To obtain a significant effect, it is necessary however to have a large
quantity of solid-liquid phase-changing materials (typically twice as much as the
adsorbents to get a significant effect). This U.S. Pat. No. 4,759,191 also mentions
the possibility of using a liquid-gas phase-changing material as well as adsorbent
temperatures of up to 100° C. or even 110° C. However, the constraints
related to the implementation of such a device are not analyzed.
SUMMARY OF THE INVENTION
The aim of the present invention is to overcome the drawbacks of the prior art.
To this end, the present invention proposes a shaping of the adsorbents that
is
particularly well suited to the discharging of the heat released during adsorption
and is economically advantageous to implement.
According to the invention, the adsorbents are prepared in the form of
rigid blocks having cavities. At least a part of these cavities is used to enhance
the distribution of the vapors of the refrigerant liquid for efficient adsorption
and another part can be used to discharge the heat released during the adsorption.
In the case of applications to cyclical devices, the cavities dedicated to the
discharging of the heat by which it is also possible to heat the adsorbents for
their regeneration.
The invention relates more particularly to an adsorption refrigeration device
comprising an evaporator chamber containing a refrigerant liquid with its vapors
that evaporates under the effect of a depression, a connecting device and an adsorption
chamber under vaccum containing an adsorbent capable of fixing the vapors of the
refrigerant liquid, wherein the adsorbent is constituted by one or more rigid blocks
comprising a plurality of cavities, at least one part of said cavities being feeder
cavities capable of diffusing vapors of refrigerant liquid on the adsorbent.
According to one characteristic, at least one other cavity is a heat-exchange
cavity capable of discharging the heat released during the adsorption of the vapors
of the refrigerant liquid.
According to one particular feature of the invention, the block has two
zones separated by a thermally conductive vacuum-tight sheathing, the first zone
comprising the adsorbent and the feeder cavities and opening on one face of the
block in the adsorption chamber, and the second zone comprising the at least one
heat-exchange cavity and opening on the opposite face of the block on the outside
of the adsorption chamber.
According to one embodiment, the sheathing comprises at least one metal
tube that sheath the at least one heat exchange cavity.
According to another embodiment, the first zone of the block contains metallic
ribs thermally bonded to the sheathing, advantageously in aluminum.
According to another embodiment, the sheathing consists of a plastic film
resting on the walls of the second zone of the block and bonded to the adsorption chamber.
According to one characteristic, the adsorbent is a zeolite.
Depending on the modes of implementation, the refrigerant liquid is water
and/or an alcohol.
According to one characteristic, the block furthermore has a thermal insulation
on its periphery advantageously constituted by a mixture of adsorbent and resin.
According to a first application, the device according to the invention
is a single-use device.
According to one characteristic, the at least one heat-exchange cavity
contains a heat sink constituted by a phase-changing material.
According to a first embodiment, the phase-changing material passes from
the solid state to the liquid state.
According to a second embodiment, the phase-changing material passes from
the liquid state to the gas state.
According to one characteristic, the second zone of the adsorbent block
comprises a vapor diffusion device, advantageously, the vapor diffusion device
consists of a hydrophobic porous material.
According to another characteristic, the second zone of the block comprises
a lid with at least one aperture to the outside atmosphere constituted by at least
one hole that limits the flow rate of the vapor of the phase changing material.
According to a characteristic, the vapor of the phase changing material
undergoes adiabatic expansion through said at least one hole so as to lower the
temperature when it escapes outwards, advantageously, the lowering of the temperature
of the vapor is greater than or equal to 35° C.
According to one implementation, the phase-changing material comprises
an aromatic additive releasing a sense of freshness.
According to a second application, the device according to the invention
is a cyclical-use device comprising an adsorption phase and an adsorbent regeneration
phase, the at least one heat-exchange cavity being furthermore capable of heating
the adsorbents for their regeneration.
According to one characteristic, the at least one heat-exchange cavity
contains a heat-carrying fluid consisting of a liquid-gas phase-changing material.
According to another characteristic, the at least one heat-exchange cavity
is closed by a dome whose external surface is in contact with a fluid flowing in
a thermal circuit.
According to another characteristic, the at least one heat-exchange cavity
comprises at least one tube for the supply of heat-carrying fluid.
According to one feature, the boiling temperature of the heat-carrying
fluid is different in the two distinct phases of adsorption and regeneration.
According to one characteristic, the boiling temperature of the heat-carrying
fluid is regulated by the pressure of the fluid flowing in the thermal circuit
in contact with the domes.
BRIEF DESCRIPTION OF THE DRAWINGS
The particular features and advantages of the invention shall appear clearly
from the following description, given by way of an non-restricted illustration,
and made with reference to the appended drawings, of which:
FIGS. 1
a and 1
b are schematic cross-sectional views of
a portion of an adsorbent block of the device according to a first and second embodiment
of the invention;
FIGS. 2
a and 2
b are respectively a schematic cross-sectional
view and longitudinal view along AA of a portion of an adsorbent block of the device
according to a third embodiment of the invention;
FIG. 3
a is a diagram of the device according to the invention in a first
single-use application;
FIG. 3
b is a diagrammatic view in longitudinal section of a portion A
of the device according to the invention shown in FIG. 3
a;
FIG. 4
a is a diagram of the device according to the invention in a second
single-use application;
FIG. 4
b is a diagrammatic view in longitudinal section of a portion A′
of the device according to the invention shown in FIG. 4
a;
FIG. 5
a is a drawing of the device according to the invention in a cyclical-use application;
FIG. 5
b is a diagrammatic longitudinal section view of a portion B of
the device according to the invention shown in FIG. 5
a.
MORE DETAILED DESCRIPTION
The invention proposes to obtain a particular shaping of the adsorbents that
gives firstly efficient adsorption and secondly easy discharge of the heat released
by the adsorption reaction and fast regeneration of said adsorbents if necessary.
Referring to FIGS. 1
a-b and
2a-b, the device according
to the invention presents the general shape of a block
200 consisting of
adsorbents
205 shaped and placed in an adsorption chamber
300 comprising
a heat insulation
350 on its periphery. In those figures, the block
200
is circular but other shapes can be envisaged, especially a rectangular shape.
According to an essential characteristic of the invention, the block
200
of adsorbents
205 has a plurality of cavities
210,
220 obtained
during the shaping of said adsorbents
205 in a block
200. The sections
of these cavities
210,
220 may be identical or may vary depending
on the desired application.
The device according to the invention comprises at least one evaporator chamber
containing a refrigerant liquid L capable of evaporating under the effect of a
depression. After opening of the connecting device, the vapors V of this liquid
L are adsorbed in the adsorption chamber by the adsorbent
205 shaped according
to the invention. This association shall be described more fully hereinafter with
reference to FIGS. 3
a and
4a.
The refrigerant liquid L is preferably water but it may also be alcohol (methanol, ethanol).
The adsorbent
205 is preferably a zeolite. For example, a zeolite 13X
or zeolite 4A made of fine powder (with a grain size of some microns to some tens
of microns) mixed with a binder (a clay, for example kaolin or other additives
known by those skilled in the art), and water to give a thick paste that can be
shaped in a block
200 provided with cavities
210,
220.
The heat insulation
350 on the periphery of the block
200 is advantageously
provided by zeolites impregnated with resin in order to obstruct their porosity
to prevent them from adsorbing water vapor. This heat insulation
350 furthermore
contributes to the rigidity and robustness of the block
200 which is then
vacuum-assembled in the adsorption chamber
300, made of aluminum or steel
for example.
At least one part of the cavities consists of feeder cavities
210 used
for the diffusion of the vapors V of the refrigerant liquid L. According to one
embodiment (FIG. 1
a), all the cavities
210 may be assigned to this
function of diffusion of the vapors V of the refrigerant liquid L without any need
for a discharge of heat. It can then be expected that the efficiency of the adsorbent
205 per unit of mass, as the temperature rises, will be limited. For certain
devices in which a large quantity of adsorbent can be used, this configuration
can be favored for its simplicity to manufacture.
According to another embodiment (FIG. 1
b), only one part of the
cavities are feeder cavities
210, the other part being heat-exchange cavities
220 designed to discharge the heat released by the reaction of adsorption
and possibly the regeneration of the adsorbents in the case of a cyclical device.
Advantageously, one in every two cavities is assigned to this function.
The adsorbent block
200 essentially has two zones separated by a sheathing
230, that is vacuum-tight but nevertheless has efficient heat exchange (FIG.
3
b). A first zone
215 under vacuum contains the adsorbent
205,
zeolites for example, and feeder cavities
210, and is open on one face of
the block
200 in the adsorption chamber
300. A second zone
225
under pressure contains the at least one heat-exchange cavity
220, and is
open one the opposite face of the block on the outside of the adsorption chamber.
Advantageously, the sheathing
230 is directly deposited on
the walls of the second zone
225 and bonded to the adsorption chamber
300.
Depending on the embodiments, this sheathing
230 may consist of vacuum-tight
tubes made of metal for example that sheath the heat-exchange cavities
220
or a film constituting a sealed lining such as kapton or polyimide film for example.
According to another embodiment (FIGS. 2
a and
b), the first
zone of the block
200 contains metallic ribs
235 thermally bonded
to the sheathing
230 in order to enhance the heat exchange between the heat
exchange cavity
220 and the adsorbent block
205. In this way, it
is possible to make only one heat exchange cavity
220 with one tube
230
having ribs
235 that carry on through the whole adsorbent block
205.
Advantageously, the ribs
235 are made of aluminum, as might be the tube
230 of the sheathing.
The first feeder zone
215 is connected to the evaporator chamber, and
its function is to achieve the vacuum adsorption of the vapors V of the refrigerant
liquid L. The second heat exchange zone
225 may be open to the exterior
for a discharge of the heat, or it may be sealed or closed on a cooling circuit.
These different arrangements are described more fully with reference to the applications
of the device according to the invention.
An application of the device according to the invention shall be described with
reference to FIGS. 3
a-b and
4a-b in the context of a single use.
As seen on FIG. 3
a, the adsorption chamber
300 is connected to
an
evaporator chamber
2 consisting of an airtight cavity containing a refrigerant
liquid L. A connecting device
50, consisting of a delidding means or a valve
for example, is used to activate and then maintain the flow of the vapors V of
the refrigerating liquid L. This connecting device
50 is connected to the
first zone
215 of the block
200, namely the feeder cavities
210
which diffuse the vapor V on the adsorbents
205.
The detail of FIG. 3
b enables a clear view of the sheathing
230
between the two zones
215 and
225 of the block
200.
In the application of the device according to the invention for single use, the
heat-exchange cavity
220 contains a heat sink consisting of a phase-changing
material (solid-liquid or liquid-gas depending on the embodiment).
The phase-changing material may be sodium acetate which goes from the solid phase
to the liquid phase. The second zone
225 (heat exchange zone) must then
be sealed to prevent a flow of liquid. An entirely closed block
200 may
have advantages but the quantity of phase-changing material is great because of
the latent heat of sodium acetate. This is a drawback for low-cost devices.
The phase-changing material may also be water which passes from the liquid phase
to the gas phase V′. The most efficient way to limit the rise in the temperature
of the adsorbent is to remove the calories by water evaporation, for the latent
heat of water is very high (45 KJ per mole, namely 18 g of water).
According to a first embodiment, shown on FIGS. 3
a-b, a diffusing
device
270 of the hot vapors V′ of the phase changing material may
be planned in the second zone
225 on the face of the block
200 opposite
the entrance of the vapors V of the cooling liquid L. This diffusing device
270
may consist of a hydrophobic porous layer that lets through hot vapors V′
but no liquid of the phase-changing material. Thus, despite an opening on the exterior,
the diffusing device
270 provides for mechanical protection of the adsorbent
block
200 and sealing of the phase changing materiel.
In that way, the second zone
225 is opened on to the exterior to let the
vapor V′ escape and remove the heat released by the adsorption reaction.
However, for fast evaporation, the water should be brought to boiling point. This
entails a potential risk of bum injuries. To avert this risk, the present invention
proposes to associate means with the adsorbent to bring down the temperature of
the released vapor.
According to a second embodiment, shown on FIGS. 4
a-b, the at least
one heat-exchange cavity
220 contains a cooling liquid (preferably liquid
water) and is placed in thermal contact with the adsorbent. This heat-exchange
cavity
220 has at least one aperture
275 to the outside atmosphere
constituted by one or more small holes that limit the flow rate of the water vapor
V′ that might escape.
According to one mode of implementation, it is possible to provide for
an additive to the liquid-vapor phase-changing material that adds an artificial
aroma to the hot vapors V′ released to the exterior of the block
200.
This artificial aroma, based on eucalyptus or watermelon for example, advantageously
produces a sense of freshness.
As shown with more details on FIG. 4
b, the heat-exchange cavity
220
has at least one aperture
275 into the outer atmosphere constituted by one
or more small holes that limit the flow rate of the vapor V′ that can escape.
This hole or these holes
275 furthermore prompt an adiabatic expansion of
the vapor V′ under pressure so as to lower the temperature when it escapes outwards.
According to one possible embodiment, the assembly constituted by the adsorbent
205 and the at least one heat-exchange cavity
220 is closed by a
lid
271 (made of metal such as aluminum for example). This lid
271
may have one or more holes
275 whose diameter is limited in order to provide
for an adiabatic expansion of the vapor V′ of the cooling liquid (the phase
changing material).
During the operation of the device, the heat released by the adsorbent
205
prompts the evaporation of the cooling liquid and an increase in the pressure of
vapor V′ inside the heat-exchange cavity
220. When the pressurized
vapor V′ escapes through the small-diameter hole or holes
275, it
undergoes adiabatic expansion or pressure reduction which lowers its temperature.
The extent of the drop in temperature of the vapor V′ escaping outwards
is all the greater as the flow rate of vapor V′ is high. This is because,
in this case, the pressure in the exchanger
220 is high and the expansion
is great.
The numerical table here below illustrates the lowering of the temperature of
the vapor V′ discharged into the outside atmosphere during the working of
the device.
|
| Temperature in the |
Pressure P1 in the |
Temperature after expansion |
| exchanger (° C.) T1 |
exchanger (bar) |
(° C.) T2 |
|
| |
| 100 |
1 |
100 |
| 105 |
1.2 |
87 |
| 110 |
1.4 |
78 |
| 115 |
1.7 |
65 |
| 120 |
2 |
55 |
| 125 |
2.3 |
48 |
|
Thus, for example, for an overpressure of one bar, the temperature of the vapor
V′ in the exchanger
220 rises to 120° C. but, after pressure
reduction through the hole or holes
275, the temperature of the discharged
vapor is no more than about 55° C. This overpressure may be achieved, for
example, by a flow rate of vapor V′ of 0.1 g/sec through a hole with a section
of 0.4 mm
2.
The cooling by adiabatic expansion or pressure reduction is governed by the following
physical law:
##EQU1##
where the pairs (T
1,P
1) and (T
2,P
2)
are the temperatures and pressures before and after pressure reduction.
And where γ is the isentropic constant,
γ=1.35 for H2O at 100° C., (γ-1)/γ=0.259
The following table illustrates the cooling capacity obtained as a function of
the overpressure caused. The vapor pressure as a function of the temperature is
taken from the Handbook of Chemistry and Physics, 80th edition. The flow rates
of the table correspond to a hole with a diameter of 1 mm (0.8 mm 2) (Flowmaster
code). The flow rate of vapor V′ is proportional to the surface area of
the hole, and the cooling capacity is proportional to the flow rate (latent heat
of vaporization of water).
| |
|
| |
T (° C.) |
P (bar) |
Flow rate g/sec |
P (Watt) |
| |
|
| |
| |
200 |
15.53 |
1.62 |
4005 |
| |
190 |
12.54 |
1.33 |
3325 |
| |
180 |
10 |
1.05 |
2625 |
| |
170 |
7.91 |
0.81 |
2025 |
| |
160 |
6.17 |
0.63 |
1575 |
| |
150 |
4.75 |
0.48 |
1200 |
| |
140 |
3.61 |
0.36 |
900 |
| |
130 |
2.70 |
0.27 |
675 |
| |
120 |
1.98 |
0.20 |
500 |
| |
115 |
1.69 |
0.17 |
425 |
| |
112 |
1.53 |
0.15 |
375 |
| |
110 |
1.43 |
0.134 |
335 |
| |
108 |
1.33 |
0.12 |
300 |
| |
106 |
1.24 |
0.10 |
250 |
| |
104 |
1.16 |
0.082 |
205 |
| |
102 |
1.08 |
0.060 |
150 |
| |
100 |
1 |
| |
|
An application of the device according to the invention shall now be described
with reference to FIGS. 5
a and
5b in the context of cyclical use.
A device of this kind has two sets of adsorbents
200 and
201 that
successively and alternately work in adsorption and regeneration phases.
A primary adsorption circuit
400 connects the adsorbent blocks
200,
201 to an evaporator
2 and a condenser
4, a two-position valve
60 being used for the alternate connection of each block
200,
201
to either of these devices. The vapor V of the refrigerant liquid L flows in this
primary circuit
400.
A secondary regenerating circuit
410 connects the adsorbent blocks
200,
201 to a heater
5 and to a cooler
6. A reversible pump
8
makes a secondary fluid Vr flow into this circuit
410. The pump
8
raises the pressure of the secondary fluid Vr in the circuit portion
410
adjacent to the block
200 in regeneration and a pressure reducer
9
located between the two blocks
200,
201 reduces the pressure of this
fluid Vr in the circuit portion
410 adjacent to the block
201 in adsorption.
The external exchange circuits are in accordance with the prior art:
- the cold is produced in the evaporator 2,
- the condenser 4 and the cooler 6, which may be series-mounted
in this order, recover the extracted calories,
- the heater 5 provides additional energy for the operation of
the device.
The detailed view B of FIG. 5
b enables a better description of the particular
features of the device according to the invention in its application to cyclical use.
The heat-exchange cavities
220 contain a heat-carrying fluid L′
consisting of a liquid-gas phase changing material such as water or alcohol and
a supply tube
240 of heat-carrying fluid L′.
According to one particular feature of the invention, these heat-exchange
cavities
220 are closed by a dome-shaped lid
250 that provides heat
exchange with the fluid Vr of the secondary circuit
410 flowing above this
surface
250. The second zone
225 of the block
200 therefore
encompasses the heat-exchange cavities
220 and their dome
250 in
the sealed sheathing
230.
The difference in temperature between the heat-carrying fluid L′ at the
bottom of the heat-exchange cavity
220 and the fluid Vr of the secondary
circuit
410 is very low (some degrees).
During the adsorption phase, the heat transmitted to the heat-exchange cavities
220, released by the adsorbent
205, causes the heat-carrying fluid
L′ to evaporate from the bottom of the cavity
220 to the dome
250
in the form of hot vapors V′ under pressure which push out the heat-carrying
fluid L′ present in the dome
250 towards the bottom of the supply
tube
240. These hot vapors V′ are then condensed in the dome
250
in contact with the fluid Vr, which is colder, of the secondary circuit
410.
Conversely, during the regeneration phase, the fluid Vr of the secondary
circuit
410 is hotter (by joint action of the heater and of the reversible
pump
8) and prompts a heating of the dome
250 leading to the evaporation
of the heat-carrying liquid L′ which gets condensed in the cavity
220,
thus yielding heat to the adsorbents
205 to be regenerated. The condensed
fluid L′ comes out of the cavity
220 through the supply tube
240
to the dome
250.
According to advantageous special characteristic of the implementation
of the invention, the boiling temperature of the heat-carrying fluid L′
is different in the two distinct phases of adsorption and regeneration, this difference
in boiling temperature being regulated by the difference in pressure of the fluid
Vr flowing in the secondary circuit
410 in contact with the dome
250
which is flexible and transmits the pressure.
One method of making the adsorbent block
200 according to the invention
shall now be specified.
Preferably, the shaping of the adsorbent block
200 with its cavities
210,
220 can be achieved by molding, injection or pressing in a mold
of a paste consisting of adsorbent powder mixed with water and a binder.
The shaping of the adsorbent block
200 may also be obtained by continuous
extrusion through a die followed by a cutting operation, for example by means of
a wire. In case the sheathing
230 consists of at least one metal tube with
ribs
235, the block
200 can advantageously be achieved by continuous
co-extrusion of the metal tube with ribs and of the adsorbent.
The block
200 is dried, at 100° C. in dry air for example, and then
totally dehydrated by firing at 450° C. in a vacuum of 0.1 Pa for example.
The periphery of the block
200 is then impregnated with resin to constitute
a heat insulation
350 and the block
200 is placed in an adsorption
chamber
300 and vacuum-sealed.
The shaping of the block
200 by molding makes it possible to obtain a
direct sealed separation
230 between the two zones
215 and
225,
by making cavities
210 and
220 that respectively open out on only
one face of the block
200. For example, the adsorbent paste
205 can
be pressed directly on to metal tubes or a sealed plastic film
230 can be
positioned on one of the faces of the mold. The conical shape of the cavities
210,
220 can be used essentially to facilitate the demolding.
In the case of a shaping of the block
200 by extrusion, the cavities
210,
220 are open on both sides of the block
200. Pierced metal grids
may be bonded on either side of the block
200 in order to close one in every
two openings of cavities on each face, and a sealing film
230 may be deposited,
by spraying for example, on the cavities
220 designed for the heat exchange.
*
