WO2010063840A2

WO2010063840A2 - Evaporator of a cooling machine

Info

Publication number: WO2010063840A2
Application number: PCT/EP2009/066436
Authority: WO
Inventors: Alexander Teusser; Ulrich Barth
Original assignee: Solarcool Ag
Priority date: 2008-12-04
Filing date: 2009-12-04
Publication date: 2010-06-10
Also published as: WO2010063842A2; WO2010063842A3; EP2359078A2; WO2010063840A3; EP2356383A2

Abstract

The present invention discloses an evaporator (1000) of a diffusion-absorption cooling machine. The evaporator is characterized by comprising an evaporator head (1105) or cover extending to a jacket wall (1100) enclosing a jacket cavity (1400) which houses a plurality of evaporator tubes (1115); and a flow limiter adapted to receive a refrigerant via a refrigerant intake (1150) and causing at least approximately equable dispersion of the refrigerant into each of the plurality of evaporator tubes (1115), wherein the dispersal of refrigerant into the plurality of evaporator tubes (1115) takes place in a pressure-less manner.

Description

EVAPORATOR OF A COOLING MACHINE

FIELD OF THE INVENTION

[0001] The present invention relates to the field of cooling machines and more particularly to the field of Diffusion-Absorption Cooling Machines.

BACKGROUND OF THE INVENTION

[0002] The invention relates to a refrigerating unit, which can be operated by means of a thermal solar system as energy source, according to the preamble of claim 1. [0003] In the prior art, the general concept of a refrigeration-unit that is based on the concept of a diffusion-absorption mechanism, has been disclosed in US patent 7201017 to Barth et al, which teaches a refrigerating unit having an expeller, a triple heat exchanger, a condenser, an evaporator, a gas heat exchanger, an absorber, and a fuel reservoir which are actively connected to form a closed fuel circuit with one another. Such a diffusion-absorption refrigerating unit is suitable to be operated by means of various energy sources. Among these, a thermal solar system as well as another heat transfer medium circuit, e.g. from a heat recovery process, can be used for the alternative or enhancing energizing of the refrigerating unit. A diffusion-absorption refrigerating unit is thus advantageously suitable, in a manner which is flexible and favorable for operation, to be energized with thermal energy by means of a thermal solar system as well as, if needed or desired, by additional or alternative energy sources. [0004] Generally, the refrigerating unit is characterized by comprising solely non- moving parts (i.e., for example, no pumps and/or compressors). As a consequence, the refrigeration unit is maintenance-friendly, relatively favorable from the standpoint of cost and can be operated, at least nearly without noise. Furthermore, it is possible to develop the refrigerating unit so that the mounting of several refrigerating units in parallel can be realized in a relatively simple manner.

[0005] The unit can be actively connected to an expeller formed as a gas bubble pump for the desorption and vaporization of a fuel contained in a solution. A gas bubble pump is particularly suitable for desorbing and vaporizing, in a manner which is effective and favorable for operation, a fuel contained in a solution such as, for example, ammonia (NH3) in an ammonia-rich solution. Furthermore, a gas bubble pump permits an efficient heat transfer accomplished by means of a thermal energy source, which is a prerequisite for reliable and effective desorption and vaporization of the fuel (ammonia). [0006] Nevertheless, the performance of the unit disclosed in US patent 7201017 has to be further improved in terms of efficiency. It is thus an object of the invention to provide a refrigeration unit having improved performance over the refrigeration unit disclosed in the prior art.

BRIEF DESCRIPTION OF THE FIGURES

[0007] The invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawings in which: [0008] Figure 1 is a schematic cross-sectional side view illustration of an evaporator, according to an embodiment of the invention;

[0009] Figure 2 is a detailed schematic cross-sectional side view illustration of a crevice in the evaporator, according to an embodiment of the invention; [0010] Figure 3 is another schematic cross-sectional side view illustration of the evaporator, according to an embodiment of the invention;

[0011] Figure 4 is schematic top view illustration of a distribution plate of the evaporator, according to an embodiment of the invention;

[0012] Figure 5 is a perspective view of a deflector and the evaporator tubes of the evaporator, according to an embodiment of the invention;

[0013] Figure 6 is a schematic cross-sectional side view illustration of a unitary component assembly evaporator - gas heat exchanger - absorber, according to an embodiment of the invention; and

[0014] Figure 7 is a schematic cross-sectional side view illustration of an impelling unit, according to an embodiment of the invention; and

[0015] Figure 8 is a schematic cross-sectional side view illustration of a pre-cooling configuration before the evaporator.

DESCRIPTION OF THE INVENTION

[0016] It should be noted that a reference to "a" or "an" element should not necessarily be interpreted as being only one of that element. Accordingly, a reference to "a bypass tube" for example may also be interpreted as "at least one bypass tube". [0017] Summary of the embodiments of the invention [0018] The present invention discloses an evaporator of a cooling machine. [0019] In embodiments of the invention, the evaporator includes an evaporator head or cover extending to a jacket wall enclosing a jacket cavity which houses a plurality of evaporator tubes.

[0020] In embodiments of the invention, the evaporator includes a flow limiter adapted to receive a refrigerant (e.g., Ammonia) via a refrigerant intake and causing at least approximately equable dispersion of the refrigerant into each of the plurality of evaporator tubes, wherein the dispersal of refrigerant into the plurality of evaporator tubes takes place in a pressure-less manner.

[0021] In embodiments of the invention, the evaporator includes a bypass tube adapted to guide a refrigerant-low fluid from a gas heat exchanger or absorber into the evaporator head.

[0022] In embodiments of the invention, the evaporator includes a distributor ring extending upwardly from the perimeter of a distributor plate, wherein the distributor ring and the jacket wall form an annular space running between the distributor ring and the jacket wall.

[0023] In embodiments of the invention, the annular space is adapted to receive and at least approximately equably disperse refrigerant over the perimeter of the evaporator head.

[0024] In embodiments of the invention, the evaporator tubes are fixated within the jacket wall by an upper end plate.

[0025] In embodiments of the invention, the flow limiter includes a plurality of distributor sleeves protruding from the underside of the distributor plate, wherein each of the plurality of distributor sleeves is sized to be insertable into a respective one of the plurality of evaporator tubes such to form a respective plurality of annular gaps between the plurality of distributor sleeves and the plurality of evaporator tubes, respectively.

[0026] In embodiments of the invention, the evaporator includes a crevice formed between the distributor plate and the upper end plate, the crevice or gap allowing flow

(e.g., at least approximately radial) of refrigerant from the annular space towards the annular gaps in the respective evaporator tubes, wherein the annular gaps and the crevice restrict the flow of refrigerant from the distributor ring towards the evaporator tubes. [0027] In embodi merits of the invention, the evaporator includes a plurality of intermediate channels running from the distributor ring (e.g., at least approximately radially) towards or in direction of the center of the distributor ring such to divide the flow limiter into a plurality of sectors, wherein the intermediate channels communicate with the annular space such to enable flow of refrigerant from the distributor ring into the evaporator tubes via the intermediate channels.

[0028] In embodiments of the invention, the evaporator tubes are at least approximately equably distributed over the cross-sectional area of the jacket cavity. [0029] In embodiments of the invention, the evaporator tubes are distributed over the cross-sectional area of the jacket cavity such that the flow rate of the refrigerant into the evaporator tubes is at least approximately equal.

[0030] In embodiments of the invention, the flow limiter further comprises the plurality of distributor sleeves that protrude upwardly from the distributor plate such to avoid inflow of refrigerant possibly collected on the distributor plate into the plurality of evaporator tubes directly through the opening of the plurality of distributor sleeves, thus confining refrigerant to flow through the crevice and retaining a pressure gradient across the upper end plate such that flow rate into each of the evaporator tubes is at least approximately equal.

[0031] In embodiments of the invention, the plurality of distributor sleeves are mechanically coupled (e.g., point welded) with a distribution plate and/or the upper end plate.

[0032] In embodiments of the invention, the upper end plate comprises a plurality of evaporator tubes grouped together with respect to a plurality of cross-sectional sectors, wherein in each sector, the distance between neighboring evaporator tubes is smaller then the average width of the intermediate (e.g., supply) channels separating the sectors from one another. [0033] In embodi merits of the invention, the bypass tube is located in any position with respect to the jacket wall.

[0034] In embodiments of the invention, the bypass tube is located in an at least approximately centered position with respect to the perimeter of the jacket wall.

[0035] In embodiments of the invention, the evaporator includes deflectors in the evaporator jacket cavity of the jacket wall to increase the rate of heat exchange between a refrigerant agent (e.g., water, or water with Antifreeze) flowing in the evaporator jacket cavity, and the refrigerant (e.g., Ammonia).

[0036] In embodiments of the invention, the deflectors form an essentially spiral flow chamber in the jacket cavity.

[0037] In embodiments of the invention, the deflectors include a plurality of level plates that are at least approximately parallel and vertically displaced with respect to each other along the evaporator tubes, and which are connected by transition plates, wherein the level plates extend partially across evaporator jacket cavity and abut outer walls of bypass tube and tubes.

[0038] Detailed description of the invention

[0039] Reference is now made to Figure 1.

[0040] Refrigerant dispersal in the evaporator

[0041] The dispersal of the refrigerant into an evaporator 1000 and subsequently to individual evaporator tubes 1115 takes place in a manner that is free of pressure (i.e., without actively applying external hydraulic pressure). The refrigerant is provided via a refrigerant intake 1150.

[0042] Distributor ring

[0043] Additional reference is now made to Figure 2. A distributor ring 1130 is located in evaporator head 1105. Together with a jacket wall 1100 of evaporator head 1105, they form an annular space 1135 in which the refrigerant is dispersed over the entire perimeter of evaporator head 1105. Distributor ring 1130 is located on an upper end plate 1160. Between distributor ring 1130 and upper end plate 1160 is a crevice 1170 through which the refrigerant flows underneath a distributor plate 1180. Distributor ring

1130 is fastened to upper end plate 1160.

[0044] Distributor plate

[0045] Distributor plate 1180 serves to disperse the refrigerant uniformly in the horizontal direction on upper end plate 1160.

[0046] Distributor sleeves

[0047] Further reference is now made to Figure 3.

[0048] A plurality of distributor sleeves 1120 is inserted in the upper end of each evaporator tube 1115, respectively. Each distributor sleeve 1120 has a specified insertion depth and a specified protrusion. The outside diameter of distributor sleeves

1120 have a dimension which is smaller than the inside diameter of evaporator tube

1115 by a specified value thus forming an annular gap 1190 therebetween, which serves on the one hand to restrict the amount of refrigerant which flows into evaporator tubes 1115 and on the one other hand, serves to form a refrigerant film on the inner side of evaporator tubes 1115. Distributor sleeves 1120 are fastened to distributor plate

1180, in an at least approximately horizontal manner.

[0049] Hole pattern for upper end plate

[0050] Additional reference is now made to Figure 4.

[0051] The pattern of holes in upper end plate 1160 is arranged or grouped together such to form individual sectors 1128. More specifically, by sectohally grouping a plurality of evaporator tubes 1115 together (according to the hole pattern), wherein within the respectively formed sector 1128 the distance between neighboring evaporator tubes 1115 is smaller (e.g., by 0.5*W) than the width W between each sector 1128, intermediate channels 1127 (of width W) are formed, which are schematically illustrated by the dashed lines. A bypass tube 1140 is located at any position with respect to upper end plate 1160, wherein bypass tube 1140 serves to guide refrigerant-low auxiliary gas (e.g., helium) from a gas heat exchanger (not shown) or absorber (not shown) into evaporator head 1105. Bypass tube 1140 is advantageously located at the center of upper end plate 1160 (with respect to the top cross-sectional area of upper end plate 1160). [0052] Deflectors

[0053] Further reference is now made to Figure 5. In an embodiment of the invention, evaporator 1000 includes deflectors 1300 that are incorporated in evaporator jacket cavity 1400 to increase the rate of heat exchange between a refrigerant agent (e.g., water, or water with Antifreeze) flowing in the evaporator jacket cavity, and the refrigerant (e.g., Ammonia). The deflection is advantageously effected in a spiral manner about bypass tube 1140 of evaporator 1000. For example, deflectors 1300 may be implemented by a plurality of level plates 1350 that are at least approximately parallel and vertically displaced with respect to each other along evaporator tubes 1115. These level plates 1350 extend partially across evaporator jacket cavity 1400 and abut outer walls of bypass tube 1140 and evaporator tubes 1115. More specifically, each level plate 1350 may have the shape of a circular sector extending over a corresponding portion of the cross-sectional area of jacket cavity 1400 and leaving a complementary cross-sectional area thereof uncovered. Moreover, neighboring level plates 1350 are rotated with respect to each other such that each one complementarily extends over the uncovered section of its neighboring lower level plate 1350 wherein baffle plates 1351 of deflectors 1300 run vertically and connect between subsequent level plates 1350 such to form a flow chamber 1401 of essentially spiral form enabling continuous flow of medium therein, as is schematically indicated with arrow F. [0054] Solution distribution in the absorber [0055] The distribution of the refrigerant-low solution to individual absorber tubes proceeds similarly to the refrigerant distribution in the evaporator. However, if the refrigerant-low solution is not guided laterally into the absorber by from below through the lower and upper absorber end plate, the distributor ring may then be omitted. Instead, an opening should be provided in distributor plate through which the refrigerant-low solution can flow into the absorber head. [0056] Component assembly: evaporator - gas heat exchanger - absorber [0057] Reference is now made to Figure 6. In some embodiments, a gas heat exchanger 610 and an absorber 620 are connected constructively to form a unitary or single integrated functional unit 600, thereby possibly increasing the compactness of the cooling machine.

[0058] A collecting chamber 615 for the refrigerant-rich auxiliary gas may have to be provided between absorber 620 and gas heat exchanger 610 for connection of absorber 620 with gas heat exchanger 610. From collecting chamber 615 at least one bypass tube 640 passes by its absorber head 622 into the lower region of absorber 620. The refrigerant-rich auxiliary gas is distributed there to individual absorber tubes 625. At least one transfer tube 630 passes through collecting chamber 615 which passes the refrigerant-low auxiliary gas from absorber head 622 into gas heat exchanger 610. Lower end plate 616 of collecting chamber 615 is provided with openings (not shown) through which unvapohsed refrigerant can pass into absorber 620. Gas heat exchanger tubes 650 are guided seamlessly as far as lower gas heat exchanger end plate 611 to connect evaporator 1000 with gas heat exchanger 610. Accordingly, the continuation of gas heat exchanger tubes 650 are evaporator tubes 1115. The lower evaporator end plate 612 thus constitutes then at the same time upper gas heat exchanger end plate 612. Evaporator tubes 1115 are connected in a gastight manner and in a pressure-tight manner to the required extent to the upper evaporator end plate (not shown) and to lower evaporator end plate 612 and lower gas heat exchanger end plate 611 by suitable means such as, for example, welding, soldering, bonding or rolling. In an alternative embodiment of the invention, instead of connecting evaporator 1000 with gas heat exchanger 610, another collecting chamber (not shown) for the refrigerant-rich auxiliary gas may be created between evaporator 1000 and gas heat exchanger 610. Bypass tube 1140 of evaporator 1000 for the refrigerant-low auxiliary gas may be passed through this other collecting chamber. Evaporator tubes 1115 are connected in a gastight manner and in a pressure-tight manner to the required extent to the upper and lower evaporator end plate 612 by suitable means such as, for example, welding, soldering, bonding or rolling. As a consequence, gas exchanger tubes 610 are connected in a gastight manner but no longer necessarily in a pressure-tight manner to the upper and lower gas heat exchanger end plate by suitable measures.) [0059] Impelling unit

[0060] Reference is now made to Figure 7. An impelling unit 700 of a cooling system is in an embodiment of the invention a tube-in-tube heat exchanger having at least one perpendicularly upright interior ascending pipe 720, which is surrounded by the impelling unit's jacket wall 710. The refrigerant-rich solution coming from the solution heat exchanger or absorber flows via opening 702 from bottom to top in ascending pipe(s) 720 exits via opening 703 to the generator. In jacket cavity 740, the refrigerant- low solution received from the generator via opening 701 flows from top to bottom in counterflow via opening 704 to the solution heat exchanger or absorber. As a result of the higher temperature of the refrigerant-low solution compared to the refrigerant-rich solution, the refrigerant-low solution transfers heat to the refrigerant-rich solution. Refrigerant is thereby converted into the gaseous phase collected in vapor dome 730 and flows via gas opening 705 to the dephlegmator (not shown) or condenser (not shown). [0061] The refrigerant-rich solution flows away in the direction of the generator. It is important that the outflow takes place at a lower level than the liquid level of the solution in the reservoir of the absorber.

[0062] It should be noted that heating of the refrigerant-rich solution is occurs by the hot refrigerant-low solution. Accordingly, the main function of the impelling unit is the one of a solution heat exchanger, i.e., in the case of the embodiment of the invention, facilitating heat transfer from the refrigerant-rich solution to the refrigerant-low solution. [0063] Pre-cooling of the refrigerant before the evaporator [0064] Reference is now made to Figure 8.

[0065] A connecting tube may be provided between a condenser 850 and an evaporator head 1105 which is dimensioned so that in addition to a refrigerant 830 liquefied in the condenser, a gas phase 840 can also coexist. This serves to provide the necessary pressure compensation between condenser 850 and evaporator head 1105. As a result of circulation of the auxiliary gas in this gas phase 840, a pre-cooling of refrigerant 830 takes place due to partial evaporation of refrigerant 830. The pre- cooling can be further increased by communicably coupling in parallel a separate gas line 810 above connecting tube 820. Gas line 810 is connected to evaporator head 1105 and the transition between condenser 850 and evaporator head 1105. Alternatively, gas line 810 can also run inside connecting tube 820. Suitable measures should be taken to prevent any penetration of liquid refrigerant 830 into gas line 810. [0066] It should be noted that the present invention may be employed in association with various energy sources, including but not limited to, any type of passive energy sources such as, for example, e.g., solar energy, process heat, and the like. In some embodiments, the cooling machine may be employed as a heating pump. [0067] While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the embodiments. Those skilled in the art will envision other possible variations, modifications, and programs that are also within the scope of the invention.

Claims

Claims:

1. An evaporator (1000) of a diffusion-absorption cooling machine said evaporator characterized by comprising an evaporator head (1105) or cover extending to a jacket wall (1100) enclosing a jacket cavity (1400) which houses a plurality of evaporator tubes

(1115); and a flow limiter adapted to receive a refrigerant via a refrigerant intake (1150) and causing at least approximately equable dispersion of the refrigerant into each of said plurality of evaporator tubes (1115), wherein the dispersal of refrigerant into said plurality of evaporator tubes (1115) takes place in a pressure-less manner.

2. The evaporator (1000) according to claim 1 comprising at least one bypass tube (1140) adapted to guide a refrigerant-low fluid from a gas heat exchanger or absorber into said evaporator head (1105).

3. The flow limiter according to any of the preceding claims, wherein said flow limiter comprises a distributor ring (1130) extending upwardly from the perimeter of a distributor plate (1180), wherein said distributor ring (1130) and said jacket wall (1100) form an annular space (1135) running between said distributor ring (1130) and said jacket wall (1100), said annular space (1135) adapted to receive and at least approximately equably disperse refrigerant over the perimeter of said evaporator head (1105).

4. The evaporator (1000) according to any of the preceding claims, wherein said evaporator tubes (1115) are fixated within said jacket wall (1100) by an upper end plate (1160).

5. The evaporator (1000) according to any of the preceding claims, wherein said flow limiter comprises a plurality of distributor sleeves (1120) protruding from the underside of said distributor plate (1180), wherein each of said plurality of distributor sleeves (1120) is sized to be insertable into a respective one of said plurality of evaporator tubes (1115) such to form a respective plurality of annular gaps (1190) between said plurality of distributor sleeves (1120) and said plurality of evaporator tubes (1115), respectively.

6. The evaporator (1000) according to claim 5, comprising a crevice (1170) formed between said distributor plate (1180) and said upper end plate (1160), said crevice (1170) allowing flow of refrigerant from said annular space (1135) towards said annular gaps (1190) in said respective evaporator tubes (1115), wherein said annular gaps (1190) and said crevice (1170) restrict the flow of refrigerant from said distributor ring (1130) towards said evaporator tubes (1115).

7. The evaporator (1000) according to any of the preceding claims comprising a plurality of intermediate channels (1127) running from said distributor ring (1130) in direction of the center of the distributor ring (1130) such to divide said flow limiter into a plurality of sectors (1128), wherein said intermediate channels (1127) communicate with said annular space (1135) such to enable flow of refrigerant from said distributor ring (1130) into said evaporator tubes (1115) via said intermediate channels (1127).

8. The evaporator (1000) according to any of the preceding claims, wherein said evaporator tubes (1115) run lengthwise in said jacket cavity (1400) from the top to the bottom of said jacket cavity (1400).

9. The evaporator (1000) according to any of the preceding claims, wherein said evaporator tubes (1115) are incorporated within said jacket cavity (1400) with respect to the cross-sectional area of said jacket cavity (1400) such that the flow rate of the refrigerant into said evaporator tubes (1115) is at least approximately equal.

10. The evaporator (1000) according to any of the claims 3-9, wherein said flow limiter further comprises said plurality of distributor sleeves (1120) that protrude upwardly from said distributor plate (1180) such to avoid inflow of refrigerant possibly collected on said distributor plate (1180) into said plurality of evaporator tubes (1115) directly through the upper opening of said plurality of distributor sleeves (1120), thus confining refrigerant to flow through said crevice (1170) and retaining a pressure gradient across said upper end plate (1160) such that flow rate into each of said evaporator tubes (1115) is at least approximately equal.

11. The evaporator (1000) according to any of the claims 3-10, wherein said plurality of distributor sleeves (1120) are mechanically coupled (e.g., point welded) with a distribution plate (1180) and/or said upper end plate (1160).

12. The evaporator (1000) according to any of the claims 4 - 11 , wherein said upper end plate (1160) comprises said plurality of evaporator tubes (1115) that are grouped together with respect to a plurality of cross-sectional sectors (1128), wherein in each sector (1128) the distance between neighboring evaporator tubes (1115) is smaller then the average width (W) of intermediate channels (1127) separating the sectors (1128) from one another.

13. In embodiments, the intermediate channels (1127) run from the distributor ring (1130) in direction of the center of the upper end plate (1160).

14. The evaporator according to any of the claims 2-12, wherein said bypass tube (1140) is located in any position with respect to said jacket cavity (1400).

15. The evaporator according to claim 2, wherein said bypass tube (1140) is located in an at least approximately centered position with respect to the perimeter of said jacket wall (1100).

16. The evaporator according to any of the preceding claims comprising deflectors (1300/1350/1351 ) in the evaporator jacket cavity (1400) of said jacket wall (1100) thus increasing the rate of heat exchange between a refrigerant agent flowing in the evaporator jacket cavity and the refrigerant.

17. The evaporator according to claim 15, wherein said deflectors (1300/1350/1351 ) form an essentially spiral flow chamber (1401 )

18. The evaporator according to claim 15 or 16, wherein said deflectors (1300/1350/1351 ) comprise a plurality of level plates (1350) that are at least approximately parallel and vertically displaced with respect to each other along said evaporator tubes (1115), and which are connected by transition plates (1451 ), wherein said level plates (1350) extend partially across evaporator jacket cavity (1400) and abut outer walls of bypass tube (1140) and tubes (1115).