CA2666172A1

CA2666172A1 - Absorption refrigerator

Info

Publication number: CA2666172A1
Application number: CA002666172A
Authority: CA
Inventors: Gerhard Kunze
Original assignee: Econicsystems Innovative Kuehlloesungen Gmbh; Inner Circle Un Ltd.; Gerhard Kunze
Current assignee: ECONICSYSTEMS INNOVATIVE KUEHLLOESUNGEN GmbH; INNER CIRCLE UN Ltd
Priority date: 2006-10-19
Filing date: 2007-10-04
Publication date: 2008-04-24
Also published as: AT504399A1; EP2082175A2; WO2008046120A2; WO2008046120A3; NO20091911L; AU2007312922A1; AT504399B1

Abstract

Disclosed is an absorption refrigerator, particularly for operation in combination with a thermal solar power plant, comprising a generator (6) to which a heating medium is applied to expel the coolant, especially ammonia, from a solution, an evaporator (13) that can be penetrated by a cooling medium, a condenser (8) to which a recooling medium can be applied to liquefy the evaporated coolant, as well as an absorber (17, 19) and a pump that are interconnected and allow a coolant solution, e.g. a water-ammonia solution, to circulate. The pump is connected to the absorber (17, 19) at the intake end and to the generator (6) at the discharge end and is embodied as a steam pump (100) that is provided with a pump intake vessel (26). In order to be able to operate said absorption refrigerator without or with only minor variations in the cooling temperature and provide a long service life, the steam pump (100) is fitted with a pressure booster (27) which is disposed below the level of the pump intake vessel (26) and to which the heating medium can be applied, a pressure reducer (30) which is disposed below the level of the pressure booster (27) and to which the recooling medium can be applied, and a pump discharge vessel (46) that is disposed below the level of the pressure reducer (30).

Description

Absorption refrigerator The invention relates to an absorption refrigerator according to the preamble of Claim 1.
Adsorption and absorption refrigerators are suitable for solar refrigerators.
Currently, the former are preferably used, although absorption refrigerators, in particular those which are operated using the coolant ammonia and the absorption agent water, have significant advantages:
significantly lower refrigerating temperatures can be achieved and, with suitable construction, the temperature coefficient can be much better than that of adsorption refrigerators. However, this is opposed by an array of obstacles in the current prior art.
GB 2 044 097 A relates to a heat pump which comprises a vapor pump.
DE 34 17 880 A describes an absorption heat pump having a pump, implemented as a diaphragm pump, for pumping a solution.

US 2 688 923 A discloses a solar energy pump. The solar energy pump comprises, inter alia, a reflector and a heater.

US 3 053 198 A relates to a normal pump which has, inter alia, a vaporization chamber, two pump chambers, and two condensation chambers.
The classical absorption refrigerator is based on the principle that a coolant dissolves very well in a liquid absorption agent at low temperature and low pressure, which occurs as an exothermic process in an absorber heat exchanger, but is expelled in vapor form in a so-called generator heat exchanger at higher temperature and also at significantly higher pressure, which is an endothermic process. If heat is now withdrawn from this coolant vapor at high pressure in a condenser heat exchanger at the so-called recooling temperature, which is usually close to the ambient temperature, the coolant liquefies. If the pressure is then reduced, the coolant can vaporize again in the vaporizer at lower temperature. This endothermic process is the actual cooling procedure. Parallel thereto, the absorption agent is also cooled to the recooling temperature. Subsequently, the gaseous coolant coming from the vaporizer and the re-cooled absorption agent are brought together again at low pressure in an absorber heat exchanger.
Absorption agent having high coolant content, as it comes from the absorber, is referred to as strong solution, and absorption agent having low coolant content, as it comes from the generator, is referred to as weak solution.

In order to get the strong solution from the absorber into the generator, a pressure barrier of 5 to 1'%4 D ED ~H.EET

la 15 bar must be overcome. A mechanical pump, such as a piston or gear wheel pump, is typically used for this purpose. Because of frequent tightness problems, larger absorption refrigerators must be emptied and maintained at least one time a year. For smaller absorption refrigerators, such a maintenance plan would be too costly. Small mechanical solution pumps -in particular for ammonia solution - having the desired freedom from maintenance for multiple years do not yet exist, however.

A ~E~[~E~
~^~ :~
~ E1-The problem of the solution transport may also fundamentally be solved using a vapor pump.
Vapor pumps are used in classical absorber refrigerators. In these cooling systems (having inert gas), the same gas pressure prevails in all components, however, and the solution only has to be pumped a small distance upward, in order to then - following gravity - flow back downward.
These pumps therefore only have to apply a slight pressure, so-called bubble pumps being used.
The active part is a vertical pipe filled with liquid, which is heated, whereby gas bubbles form, which drive the liquid upward. In the case of absorption refrigerators without inert gas, however, the solution must overcome a significantly greater pressure differential on the route from the absorber to the generator than in the cited cooling system, which is not possible using a bubble pump.
A further problem is the heat exchangers. Typically, the so-called "falling film" technology is used, the coolant solution running downward along the wall of the heat exchanger following gravity, abundant space having to be left along this wall, however, in order to allow a free inflow or outflow of the coolant vapor. This results in very large and heavy facilities. Therefore, it is typical to select the temperature differential between the primary and secondary sides of the heat exchanger as relatively great, in order to be able to make their dimensions smaller at least in this way. However, this procedure prevents the possibility of efficient heat recirculation. This is because the temperature intervals at which absorption or expulsion, respectively, occur in the generator overlap in a relatively large range, so that theoretically a large part of the absorption heat may be reclaimed for the expulsion process. However, if the temperature differential inside the heat exchanger is large, the overlap of the cited temperature intervals approaches zero.
Other heat exchangers, such as pipe bundle or plate heat exchangers, are still more problematic.
Because the flow cross-section is very large in comparison to the heat exchanger surface, the solution flows relatively slowly. Large gas bubbles may thus stop in the heat exchanger, so that only a small part of the heat exchanger cross-section is actually used. In order to prevent the formation and stoppage of larger gas bubbles, a very rapid flow through the heat exchanger is needed, which is only made possible by a very narrow flow cross-section. In order to achieve a large heat exchanger area with a narrow cross-section, a very great hydraulic length is needed, typically approximately 10 m. Such a length may only be achieved in spiral heat exchangers.
Because of the very high heat transfer coefficients in this concept, the size of the heat exchanger may be reduced by a factor of 10 in relation to the "falling film" technology.
However, spiral heat exchangers have a large flow resistance.
In the classical absorption refrigerator concept, the solution is moved by gravity to the absorber, however. Gravity cannot overcome the flow resistance of an optimally dimensioned spiral heat exchanger.

Solar cooling causes an additional problem for absorption refrigerators. In general in absorption refrigerators, for an optimum function, the mean solution concentration of the machine is a function of the heating, recooling, and desired cooling temperatures. In large typical absorption refrigerators, the heating and cooling temperatures are usually permanently predetermined. The recooling temperature is usually defined by a wet cooling tower and also only varies in a small interval. In contrast, the heating temperature varies very strongly for small solar refrigerators.
The recooling is probably caused via a fan-air heat exchanger for economic reasons, which is dependent on the ambient temperature, and thus the recooling temperature also varies in a larger interval, so that the solution concentration must be changed frequently for optimum operation.
However, a strong variation of the cooling temperature of the absorption refrigerator results from the variability of the solar energy. In the typical absorption refrigerator, the pressure differential between condenser and vaporizer is regulated via a throttle. The pressure differential is thus controlled by flow and/or power, while it is only to be a function of the differential between recooling temperature and cooling temperature in the interest of optimization.
This contradiction has the effect that the cooling process runs far from optimally under conditions of lower power, while in the moments in which the flow resistance is too low, coolant vapor also goes through the throttle in addition to condensed liquid coolant, which sensitively interferes with or prevents the following vaporization process. Similarly thereto, a passage of vapor through the throttle between generator gas precipitator and absorber may also result in malfunctions at the absorber outlet to the pump.

The object of the invention is to propose an absorption refrigerator of the type cited at the beginning which has a long lifetime and low wear. A further object is to propose an absorption refrigerator of the type cited at the beginning which has no or only slight variations of the cooling temperature.

The first object is achieved according to the invention in an absorption refrigerator of the type cited at the beginning by the features of Claim 1.

A corresponding circulation of the solution is ensured by the use of the vapor pump, mechanical moving parts being restricted to a minimum, in particular the vapor pump comprising essentially no mechanical moving parts. Therefore, almost no wear occurs in the refrigerator and it may be operated largely without maintenance and achieves a long service life. Typical electromechanical pumps, such as piston or gear wheel pumps, for transporting the strong solution from the absorber into the generator and for overcoming the pressure barrier of 5-15 bar, may thus be dispensed with.
Advantageous refinements of the vapor pump result from the features of Claims 2 through 4, the vapor pump being able to be implemented simply and being able to reliably apply the pressure required for transporting the coolant solution from the absorber to the generator.
The advantage results from the features of Claim 5 that a majority of the solution may be conveyed via the overflow pipe directly to the pump outlet vessel and does not have to be subjected to heating and subsequent cooling.
In order to be able to apply an essentially constant pressure to the generator in spite of the intermittent pumping action of the vapor pump, the features of Claim 6 are expediently provided.
If a vapor pump is used for the solution transport, power variations may occur in connection with thermal solar energy, which may in turn result in undesired variations of the cooling temperature.
The pressure in the overall cooling loop may be stabilized by the pressure stabilizer and the pressure-equalizing gas bubbles in the pressure stabilizer and the undesired variations may thus be reduced or avoided.

An especially simple and expedient embodiment of such a pressure stabilizer results from the features of Claim 7.

In order to be able to also operate the refrigerator optimally in connection with a solar plant, it is advantageous to provide the features of Claim 8. The concentration of the solution may be adapted to the particular heating temperature by these measures and optimum operation may thus be achieved.

A very simple design for a concentration regulator results from the features of Claim 9.
In order to guarantee that the vapor pump always has enough solution for the suction and to allow the use of very efficient heat exchangers, it is expedient to provide the features of Claim 10. In this way, a corresponding partial vacuum is ensured, through which the solution is also forced through heat exchangers, such as the absorber, which have a narrow cross-section and a great hydraulic length and are therefore distinguished by high efficiency.
A particularly simple design solution for a partial vacuum stabilizer results from the features of Claim 11.

In order to minimize the variations of the cooling temperature further and to be able to reuse the incidental waste heat to a large extent, it is advantageous to provide the features of Claim 12.
Furthermore, the features of Claim 13 may be provided in this context.
The advantage of efficient use of the recooling medium results from the features of Claim 14.
A large part of the incidental waste heat may be reused by the features of Claim 15, whereby the efficiency of the refrigerator is increased and the variations of the cooling temperature may be minimized further.
In order to prevent disturbances of the function of the refrigerator from occurring due to temperature-related power variations, it is advantageous to provide the features of Claims 16 and 17.

The invention will be explained in greater detail on the basis of the drawing.
Figures 1 and 2 therein show various preferred embodiments of a refrigerator according to the invention, which differ essentially in the construction of the vapor pump.

The refrigerator according to the invention has a vapor pump 100, which has a pump inlet vessel 26, a pressure booster 27 situated below the level thereof, a pressure reducer 30 situated below the level thereof, and a pump outlet vessel 46 situated below the level thereof, it being provided according to the preferred embodiment that the pump outlet vessel 46 is connected to the pump inlet vessel 26 and the pressure reducer 30, and to the generator 6.
The vapor pump 100 is connected via a pump outlet pipe 1, in which a shutoff element, in particular a check valve 12, is situated, to a pressure stabilizer 3, which is enclosed by a heating jacket 101, and via a shutoff element 4, preferably a check valve, and a flow resistance, such as a throttle 5, to a generator 6 for expelling the coolant from the solution. A
gas precipitator 7 is downstream from the generator 6, whose gas chamber is connected to a condenser 8. The condenser has a recooling medium applied to it, which enters at the inlet 42 and exits at the outlet 43.

The coolant condensate exiting from the condenser is supplied to a concentration regulator 9 via a flexible line 10. This regulator is essentially formed by a pipe which is oriented essentially horizontally and is pivotable around a horizontal axis 102. The pipe may thus be pivoted around the horizontal by a pre-definable angle, whereby more or less coolant condensate may be held in the pipe.
The concentration regulator 9 is connected via a further flexible line 11 to a shutoff element, preferably a float valve 2, which is in turn connected to a vaporizer 13, which has a cooling medium applied to it, which enters via the inlet 44 and exits at the outlet 45. The vaporizer 13 is connected to a hot absorber 17, whose cooling loop 105 has the cool heating medium flowing .through it, which exits at the outlet 41, via a line 15 in which a shutoff element, such as a check valve 14, is situated.
Before the hot absorber 17, a line 16, which is connected to a shutoff element, in particular a float valve 51, which only allows liquid, but not gas, to pass, at the liquid chamber of the gas precipitator 7, opens into the line 15.
The hot absorber 17 is connected via a U-shaped pipe 18, whose legs drop downward, to a cold absorber 19. The cold absorber 19 is connected to a partial vacuum stabilizer 20, which has a recooling medium, which flows through a cooling loop 104 in countercurrent, applied to it like the cold absorber 19.
The vapor pump 100 is between the absorber and the generator - viewed in the direction of the circulation of the coolant solution, e.g., a water-ammonia solution - the pump being connected at the inlet to the absorbers 17, 19, in particular to the hot absorber 17 and/or the cold absorber 19, and at the outlet to the generator 6.
The partial vacuum stabilizer 20 is connected via a float valve 21 and a check valve 22 to the vapor pump 100.

According to the preferred embodiment, the pressure booster 27 has the heating medium applied to it, which enters at the inlet 40 and exits at the outlet 41. The pressure reducer 30 has a recooling medium applied to it, which enters at the inlet 42 and exits at the outlet 43.
The heating medium, which enters at high temperature at the inlet 40 of a heating loop 106 of the generator 6, flows through this heating loop 106, then a heating jacket 101 of the pressure stabilizer 3, and subsequently, accordingly cooled, a heating loop 105 of the hot absorber 17 and leaves it at the outlet 41.

The cooling loop of the condenser 8 has the recooling medium flowing through it, which enters at 42 and exits at 43.
The cooling loop of the vaporizer 13 has cooling medium flowing through it and enters therein at 44 and leaves it at 45, the heat exchanger of the vaporizer preferably but not necessarily being operated in continuous current, while in contrast the remaining heat exchangers are operated in countercurrent.
The cooling loop of the partial vacuum stabilizer 20 and the cooling loop of the cold absorber 19 are connected in series, the recooling medium entering at the inlet 42 of the cooling jacket 103 of the partial vacuum stabilizer 20 and exiting at the outlet 43 of the cooling loop 104 of the cold absorber 19.
In the embodiment according to Figure 1, a pump inflow line 23, which is connected to the check valve 22, opens from above into the pump inlet vesse126, which leads away at the bottom to an S-shaped curved lift pipe 24, to which a pressure booster connection pipe 28 and a pressure reducer connection part 31 are connected.
A gas pressure equalizer pipe 25, which is connected to a pressure booster aspiration line 29 and a vapor expeller line 50, which leads to the gas chamber of the pump outlet vesse146, leads upward away from the pump inlet vessel 26.
From the pressure reducer 30, an aspiration pipe 321eads away upward, which is connected to a liquid lift pipe 33, which opens into a pump inflow pipe 38, which is connected to the liquid chamber of the pump outlet vessel 46, and in which a flow resistance is situated, in particular an adjustable throttle 39.
The strong coolant solution is pressed by the vapor pump, and/or by the pump outlet vesse146 via the shutoff element 12 into the pressure stabilizer 3. This stabilizer is used to convert the pump strokes of the solution flow into a uniformly flowing flow having an optimum pressure for the generator process. The pressure stabilizer 3 comprises a heated container of arbitrary shape, preferably a horizontal pipe, which is enclosed by a jacket 101, which has heating medium flowing through it, the pipe being dimensioned so that a gas bubble always stops in its upper part. If cold solution is pushed by the pump 100 into the pressure stabilizer 3, the pressure briefly drops in the gas bubble of the pressure stabilizer 3, which allows unobstructed inflow of the solution. Immediately thereafter, the gas pressure rises again in the pressure stabilizer 3 to just above the generator pressure, because the solution is heated up to the vaporization temperature.

In order that the solution in the pressure stabilizer 3 is heated precisely to the temperature at which the outgassing process begins in the generator 6, the heating jacket 101 of the pressure stabilizer 3 is connected to the outlet of the generator heater 106. It is ensured by the flow resistance 5, preferably a throttle, and by the shutoff element 4, preferably a check valve, that a uniform solution flow enters the generator 6. The solution flows through the generator 6 in countercurrent to the heating medium flow inlet 40, is heated, and forms gas bubbles. The use of the pressure stabilizer 3 allows the use of a heat exchanger for the generator 6 having a narrow cross-section, but having a very great hydraulic length, i.e., a heat exchanger having high flow resistance, preferably a spiral heat exchanger, and an extremely high heat transfer per unit of area is achieved because of the large flow cross-section. A particularly large temperature span of the heating medium on the route of the heating medium flow inlet 40 to the outlet of the generator 6 results therefrom. Because the heating medium cools still further during the passage through the heating jacket of the pressure stabilizer 3, its temperature is suitable for cooling the hotter part of the absorption process. Therefore, the heating medium is conducted from the pressure stabilizer 3 to the heat exchanger of the hot absorber 17, where it is reheated by the absorption process and is finally conducted at the heating medium flow outlet 41 back to the heater (not shown). A large part of the absorption heat is thus returned to the heating process. From the generator 6, the hot weak solution, including the gas bubbles formed, reaches the gas precipitator 7. The hot solution then reaches the hot absorber 17 via the shutoff element 51, preferably a float valve. From the gas precipitator 7, the gas goes into the heat exchanger of the condenser 6, where heat is withdrawn from it by the recooling medium, which flows in at 42 and flows out at 43, which results in condensation of the coolant. This coolant now runs through the flexible inflow pipe 10 to the concentration regulator 9. The concentration regulator 9 is rotatable upward or downward around a rotatable suspension in the form of a horizontal axis 102 and may be fixed in this position. Depending on the angle of inclination of the concentration regulator 9, a different quantity of coolant accumulates in the container 9 before it may flow further via the second flexible outflow pipe 11 via the float valve 2 to the vaporizer 13. The quantity of coolant accumulated in the concentration regulator 9 is withdrawn from the cooling loop, so that the mean concentration of the coolant solution in the overall machine decreases.
This adjustment capability is advantageous for solar cooling, because the optimum solution temperature is a function of the heating temperature, recooling temperature, and desired cooling temperature, these three temperatures being climate-dependent. In the vaporizer, the vaporization process of the coolant cools the cooling medium flow via 44 and 45. The coolant vapor thus resulting goes through the supply line 15 to the hot absorber 17. Immediately before entering the hot absorber 17, the supply line 15 is unified with the supply line 16, which supplies the weak solution coming from the generator 6 to the hot absorber 17. The gas flow coming from the vaporizer 13 entrains small hot solution droplets from the solution stream coming from the generator 6 and conducts them into the hot absorber 17. The hot absorber 17 is cooled in countercurrent to the solution by the cooled heating medium coming from the pressure stabilizer 3.
The temperature of the heating medium rises, so that its temperature at the outlet of the hot absorber 17 reflects the energy quantity reclaimed from the absorption process. Because the temperature of the heating medium coming from the pressure stabilizer 3 approximately corresponds to the minimal outgassing temperature of the solution at generator pressure, the absorption process cannot be terminated in the hot absorber 17, because a lower pressure prevails therein than in the generator 6, and the temperature for a complete absorption must thus also be lower than in the pressure stabilizer 3. From the hot absorber 17, the mixture made of solution and residual coolant vapor is therefore conducted via the connection line 18 into the cold absorber 19. The absorption process is terminated therein and the strong coolant solution formed is conducted into the partial vacuum stabilizer 20. This is similar in construction to the pressure stabilizer 3, but its outer jacket is cooled, so that the stored solution located in the inner pipe is always nearly at recooling temperature. It is also important in the partial vacuum stabilizer 20 that it is dimensioned so that a gas bubble may always be obtained in its upper part. The pressure in the partial vacuum stabilizer 20 is then always lower than the vapor pressure of the hot solution coming from the generator 6 through the supply line 16 or the coolant vapor coming out of the vaporizer 13 through the supply line 15. The partial vacuum stabilizer 20 therefore suctions the mixture made of coolant vapor and weak coolant solution through the two absorbers 17 and 19, even if they are implemented as high-performance heat exchangers having a narrow cross-section and great hydraulic length, which also have a relatively great flow resistance. In order to guarantee the necessary pressure gradient, the recooling medium is first to flow through the partial vacuum stabilizer 20 and only then through the cold absorber 19, the latter in countercurrent to the mixture made of solution and coolant vapor. The partial vacuum stabilizer 20 is concurrently used as a coolant solution reserve for the pump 100, so that it may operate uniformly.

The strong solution reaches the vapor pump via the shutoff element 21, preferably a float valve, and the shutoff element 22, preferably a check valve, but only during the timeslots in which the pressure in the vapor pump is low enough. If this is the case, the majority of the solution flows through the first pump inflow pipe 38 and the controllable flow resistance 39 into the pump outlet vessel 46 and fills it. However, a smaller part of the solution flows simultaneously through the second pump inflow pipe 23 into the pump outlet vessel 26. It is important that the pump inlet vessel 26 must be located at the highest point of the vapor pump - the entire section between the shutoff element 22 and 12 - the pressure booster 27 must be underneath it, the pressure reducer 30 must be below the pressure booster 27, and the pump outlet vessel 46 must in turn lie below it. The lowest level of the vapor pump is formed by the horizontal branch of the first pump inflow pipe 38, and the pump outlet pipe 1 is to branch off from the vertical leg of the first pump inflow pipe 38 below the pump outlet vessel 46. This height positioning is necessary because the solution is moved solely by gravity in the vapor pump.
The phases of the pump cycle are as follows:

First phase: The pump inlet vessel 26 and the pump outlet vessel 46 fill.
Second phase: As soon as the pump inlet vessel 26 has filled, the lift pipe 24 is also filled up to its upper apex. As soon as solution flows over this apex, the lift pipe 24 suctions solution out of the pump inlet vessel 26 and lets it flow into the lower part of the pump, namely into the pressure reducer 30 and the pressure booster 27. The solution cannot flow immediately via the liquid lift pipe 33, which connects the aspiration pipe 32 of the pump outlet vessel 46, to the lowermost part of the pump, because the static hydraulic pressure of the pump outlet vessel 46, which is filled with solution, prevents this. The quantity of the solution per pump stroke must be dimensioned so that the pressure booster 27, preferably a horizontal pipe enclosed by a heating jacket, is partially filled. In the pressure reducer 30, which is preferably formed by a horizontal pipe enclosed by a cooling jacket, a gas bubble remains, caused by the aspiration pipe 32, which opens from above into the pressure reducer 30.

Third phase: The solution heated in the pressure booster 27 discharges coolant vapor under rising pressure, which enters the pump outlet vessel 46 via the aspiration pipe 29 and the vapor expeller pipe 50 and presses the solution out of this vessel via the pump outlet pipe 1 into the pressure stabilizer 3. Simultaneously, the gas bubble in the pressure reducer 30 shrinks. During this expulsion phase, a hydraulic equilibrium prevails between the solution quantity in the pressure booster 27 and pressure reducer 30 between the solution level 34 and 35 on one side and a solution quantity in the pump outlet vessel 46 between the solution level 36 and 37 on the other side. While the solution leve136 sinks slowly, the solution level 37 also sinks, until gas from the liquid lift pipe 33 penetrates into the first pump inflow pipe 38 and then into the pump outlet vessel 46 and thus the hydraulic counterforce, which had stopped the solution in the pressure booster 27, collapses.
Fourth phase: The solution from the pressure booster 27 flows via the inflow and outflow pipe 28 into the pressure reducer 30 and from 30 via the aspiration pipe 32 and the liquid lift pipe 33 into the pump outlet vesse146. When all of the solution has drained out of the pressure booster 27, the liquid lift pipe 33 suctions on the aspiration pipe 32 again. However, gas must now enter the pressure reducer 30 via 31 and it may be expected that the original gas bubble will be produced again, in the size it had at the beginning of phase 2. Because this gas enters from below into the cold solution in the pressure reducer 30, it is absorbed immediately. It is to be noted that the coolant - preferably ammonia - only absorbs rapidly in the cold solution if it is introduced from below, but very slowly if it comes from above, because liquid ammonia floats on water. This type of the vapor pump thus only functions for pairs of coolant and absorption medium for which the same relationship applies. The pressure in the vapor pump drops suddenly due to this absorption procedure and only then does the gas bubble in the pressure reducer 30 get to its original size.
Phase 1 may now begin again.
Figure 2 shows a refrigerator according to the invention having a different vapor pump. In contrast thereto, the filling of the pump only occurs via the pump inflow pipe 23 into the pump inlet vesse126. As soon as the latter has filled with solution, it flows via the lift pipe 24 to the pressure booster 27. However, precisely at the height where the solution surface is to be in the pressure booster 27, a branch is located in the lift pipe 24 to the overflow 107, which conducts the excess solution via the pump inflow pipe 38 to the pump outlet vessel 46.
A deaeration 108 of the overflow 107 is important in this case, to prevent this transverse connection between lift pipe 24 and pump inflow pipe 38 from acting like a liquid lifter itself. The intention of the overflow 107 is to convey a majority of the solution directly to the pump outlet vessel 46, which thus does not participate in the heating and cooling in pressure booster 27 and pressure reducer 30, whereby energy is saved.

Claims

1. An absorption refrigerator, in particular for operation in connection with a thermal solar plant, having a generator (6), to which a heating medium can be applied, for expelling the coolant, in particular ammonia, from a solution, an evaporator (13), which can have a cooling medium flow through it, a condenser (8), to which a recooling medium can be applied to liquefy the vaporized coolant, an absorber (17, 19), and a pump, which are connected to one another and allow a circulation of a coolant solution, e.g., a water-ammonia solution, the pump being connected at the inlet to the absorber (17, 19) and at the outlet to the generator (6), the pump being implemented as a vapor pump (100), and the vapor pump (100) having a pump inlet vessel (26), characterized in that the vapor pump (100), to overcome a pressure barrier of 0.5 to 1.5 MPa, has a pressure booster (27), which is situated below the level of the pump inlet vessel (26) and can have the heating medium applied to it, a pressure reducer (30), which is situated below the level thereof and can have the recooling medium applied to it, and a pump outlet vessel (46), which is situated below the level thereof.

2. The absorption refrigerator according to Claim 1, characterized in that the pump outlet vessel (46) is connected to the pump inlet vessel (26) and the pressure reducer (30), and to the generator (6).

3. The absorption refrigerator according to one of Claims 1 or 2, characterized in that the pump inlet vessel (26) is connected via an S-shaped lift pipe (24), which has falling and rising sections, and whose upper apex determines the filling level of the pump inlet vessel (26), to the inlets of the pressure booster (27) and the pressure reducer (30), and is connected at the inlet to the absorber (17, 19).

4. The absorption refrigerator according to one of Claims 1 through 3, characterized in that the outlets of the pressure booster (27) and the pressure reducer (30) are connected to the pump outlet vessel (46).

5. The refrigerator according to Claim 3 or 4, characterized in that an overflow pipe (107) branches off from the lift pipe (24) at the level of the solvent surface in the pressure booster (27), which leads to a deaeration pipe (108), which is connected from above to the outlet of the pump inlet vessel (26), and which is connected to a pump inflow pipe (38), which is connected to the pump outlet vessel (46) and the outlet of the pressure reducer (30).

6. The refrigerator according to one of Claims 1 through 5, characterized in that the pump outlet vessel (46) is connected to the generator (6) via a pressure stabilizer (3), the pressure stabilizer (3) being able to have the heating medium applied to it and having room for a gas blower.

7. The refrigerator according to Claim 6, characterized in that the pressure stabilizer (3) is connected at the outlet via a flow resistance, such as a throttle (5), to the generator (6).

8. The refrigerator according to one of Claims 1 through 7, characterized in that the condenser (8) downstream from the generator (6) is connected at the outlet via a concentration regulator (9) to the vaporizer (13).

9. The refrigerator according to Claim 8, characterized in that the concentration regulator (9) is formed by a pipe running essentially horizontally, which is held so it is pivotable around a horizontal axis, in order to be able to change the extent of an accumulation, and whose two ends are connected to the condenser (8) and the vaporizer (13), respectively, via flexible lines.

10. The refrigerator according to one of Claims 1 through 9, characterized in that the vapor pump (100) is connected at the inlet via a partial vacuum stabilizer (20), which can have cooling medium applied to it, to the absorber (17, 19), the partial vacuum stabilizer (20) comprising a vessel running essentially horizontally, in which a gas blower is held.

11. The refrigerator according to Claim 10, characterized in that the partial vacuum stabilizer (20) is formed by an essentially horizontal pipe which is partially fillable by the solution, and which is cooled by the recooling medium.

12. The refrigerator according to one of Claims 1 through 11, characterized in that the absorber is divided into a cold absorber (19) and a hot absorber (17), the hot absorber (17) being connected at the inlet to the outlet of the vaporizer (13) and being connected at the outlet to the inlet of the cold absorber (19).

13. The refrigerator according to Claim 12, characterized in that the inlet of the hot absorber (17) is also connected to an outlet for the solution of a gas precipitator (7), which is interposed between the generator (6) and the condenser (8).

14. The refrigerator according to one of Claims 10 through 13, characterized in that the recooling medium is conducted via a cooling jacket (103) of the partial vacuum stabilizer (20) and subsequently via a cooling loop (104) of the cold absorber (19) connected in series thereto.

15. The refrigerator according to one of Claims 6 through 14, characterized in that the heating medium is conducted via a heating loop (106) of the generator (6), subsequently via the heating jacket (101) of the pressure stabilizer (3), which is connected in series in regard to the heating medium, and then, already cooled, via the cooling loop (105) of the hot absorber (17), which is connected in series thereto in regard to the heating medium.

16. The refrigerator according to one of Claims 1 through 15, characterized in that a flow resistance (2), which is formed by a float valve, is interposed between the condenser (8) and the vaporizer (13).

17. The refrigerator according to one of Claims 12 through 16, characterized in that a shutoff element (51), in particular a float valve, which only permits solution to flow through, is connected downstream from a gas precipitator (7) after the generator (6) in a line (16) leading to the hot absorber (17).