Note: Descriptions are shown in the official language in which they were submitted.
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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 If heat is now withdrawn from this coolant vapor at high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
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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.
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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
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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.
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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
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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.
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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.
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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.
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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,
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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.
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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
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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
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thus does not participate in the heating and cooling in pressure booster 27
and pressure reducer
30, whereby energy is saved.
