Steam generating and condensing apparatus

A steam generating and condensing apparatus having a steam generating chamber in which a diluted solution flowing from an absorption device and containing a refrigerant absorbed therein flows outside of the pipes of a steam generating heat exchanger to evaporate the refrigerant from the diluted solution with a hot fluid flowing through the pipes of the steam generating heat exchanger, and a steam condensing chamber in which the refrigerant steam supplied through a partition from the steam generating chamber is condensed by a steam condensing heat exchanger. A double-cylinder assembly is provided composed of outer and inner cylinders, with the inner cylinder being divided by a dispersing end plate into upper and lower chambers serving as a dispersing diluted solution chamber and the steam generating chamber, respectively. The inner and outer cylinders jointly define a space in which the steam condensing chamber is disposed. The partition has eliminators on an upper portion thereof. The dispersing diluted solution pool is provided with a diluted solution inlet pipe. The steam generating chamber has a concentrated solution outlet pipe in a lower portion thereof.

BACKGROUND OF THE INVENTION 
The present invention relates to a steam generating and condensing 
apparatus for use in an absorption heat pump or the like. 
A conventional steam generating and condensing apparatus is illustrated in 
FIG. 1 of the accompanying drawings. The apparatus includes a casing 1 and 
a partition 2 disposed therein dividing the interior thereof into a steam 
generating chamber 3 and a steam condensing chamber 4. Designated at 5 is 
a hot fluid, 6 a diluted solution, 7 a solution (hereinafter referred to 
as a "concentrated solution") from which refrigerant steam has been 
generated, 8 refrigerant steam, 9 a refrigerant liquid, and 10 cooling 
water. Fluids 5 through 10 are working fluids. Further, designated at 11 
is a steam generating heat exchanger, 12 a steam condensing heat 
exchanger, 13 a hot fluid inlet pipe, 14 a hot fluid outlet pipe, 15 a 
diluted-solution inlet pipe, 16 a concentrated-solution outlet pipe, 17 a 
solution pump, 18 a refrigerant pump, 19 a bypass pipe, and 20 a 
solenoidoperated valve. The components denoted at 11 through 20 constitute 
the piping of the heat generating and condensing apparatus. The hot fluid 
inlet pipe 13 is connected to the steam generating heat exchanger 11, 
which is connected to the hot fluid outlet pipe 14, so that the hot fluid 
5 flows from the inlet pipe 13 through the heat exchanger 11 out of the 
outlet pipe 14. The cooling water 10 flows through and is discharged out 
of the steam condensing heat exchanger 12. 
The diluted solution 6 from an absorption chamber (not shown in FIG. 1) in 
an absorption device flows from the diluted-solution inlet pipe 15 into 
the steam generating chamber 3 in the casing 1. The diluted solution 6 
then passes along the outer pipe surfaces of the steam generating heat 
exchanger 11 filled with the hot fluid and is vaporized or boiled on the 
outer pipe surfaces of the heat exchanger 11 due to the heat from the hot 
fluid flowing therethrough. The refrigerant in the diluted solution 6 is 
subjected to a phase change to produce refrigerant steam 8 which flows in 
a direction (indicated by dotted-line arrows) from the steam generating 
chamber 3 into the adjacent steam condensing chamber 4. The diluted 
solution 6 is concentrated as it passes along the outer pipe surfaces of 
the heat exchanger 11 and is thereby turned into the concentrated solution 
7, which is pumped by the solution pump 17 through the 
concentrated-solution outlet pipe 16 into the absorption chamber in the 
absorption device. The refrigerant steam 8 generated in the steam 
generating chamber 3 is displaced into the steam condensing chamber 4 due 
to a pressure difference, and then cooled by the cooling water 10 flowing 
through the pipes of the steam condensing heat exchanger 12. The steam 8 
is condensed on the outer pipe surfaces of the heat exchanger 12 and 
turned into the refrigerant liquid 9, which is pumped by the refrigerant 
pump 18 partly into an evaporation chamber (not shown in FIG. 1) in the 
absorption device and partly through the bypass pipe 19 into the 
concentrated solution 7 for adjusting the concentration thereof. 
In the above conventional steam generating apparatus, it is required to 
adjust the rate of flow, the temperature, the concentration of the diluted 
solution 6, and the rate of flow of the hot fluid 5 passing through the 
steam generating heat exchanger 11 for controlling the generated steam, 
and it is also required to adjust the rate of flow and the temperature of 
the cooling water 10 flowing through the steam condensing heat exchanger 
12 for controlling the condensed steam. Therefore, it has been highly 
difficult to control the generated and condensed steam. For example, when 
the refrigerant liquid 9 is condensed, the concentrated solution flowing 
out of the concentrated-solution outlet pipe 16 has a high concentration. 
To cause the concentrated solution to have a desired concentration, the 
apparatus has required the bypass pipe 19 to reflux the refrigerant liquid 
9 into the concentrated solution 7 and the solenoid-operated valve 20 to 
adjust the rate of flow of the refluxed refrigerant liquid 9. Conversely, 
when the concentrated solution has a low concentration, it has been 
necessary to control the rate of flow and the temperature of the cooling 
water 10. 
The difference between the temperatures inside and outside of the heat 
transfer pipe walls of the steam generating heat exchanger 11 immersed in 
the solution is reduced because of a substantial increase in the boiling 
point due to the height of the column of the solution. When the solution 
boils on the outer wall surfaces of the heat exchanger 11, generated steam 
bubbles, which may be combined under a certain thermal load, form a steam 
film surrounding the outer pipe surfaces, which presents a large thermal 
resistance, lowering the steam generating capability to a large extent. 
SUMMARY OF THE INVENTION 
The present invention has been made with a view of eliminating the 
foregoing shortcomings. It is specifically an object of the present 
invention to provide a steam generating and condensing apparatus having an 
increased steam generating capability, which is capable of 
self-controlling generated and condensed steam without controlling the 
flow rate and temperature of working fluids upon variation of the steam 
condensing capability, and which requires no refrigerant liquid bypass 
pipe and no solenoid-operated valve. 
The above as well as other objects of the invention are met by a steam 
generating and condensing apparatus having a steam generating chamber in 
which a diluted solution flowing from an absorption device and containing 
a refrigerant absorbed therein flows outside of the pipes of a steam 
generating heat exchanger to evaporate the refrigerant from the diluted 
solution with a hot fluid flowing through the pipes of the steam 
generating heat exchanger, and a steam condensing chamber in which the 
refrigerant steam supplied through a partition from the steam generating 
chamber is condensed by a steam condensing heat exchanger. In accordance 
with the invention, a double-cylinder assembly is provided composed of 
outer and inner cylinders, with the inner cylinder being divided by a 
dispersing end plate into upper and lower chambers serving as a dispersing 
diluted solution chamber and the steam generating chamber, respectively. 
The inner and outer cylinders jointly define a space in which the steam 
condensing chamber is disposed. The partition has eliminators on an upper 
portion thereof. The dispersing diluted solution pool is provided with a 
diluted solution inlet pipe. The steam generating chamber has a 
concentrated solution outlet pipe in a lower portion thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will now be described with reference to a preferred 
embodiment shown in FIG. 2. Identical or corresponding parts in FIG. 2 are 
denoted by identical or corresponding reference numerals in FIG. 1. Steam 
generating heat exchangers 11 are erected substantially vertically within 
a steam generating chamber 3. The interior of an inner cylinder 21 is 
divided into an upper chamber 21a and a lower chamber 21b by a dispersing 
end plate 22 having dispersing holes 22a. The steam generating heat 
exchangers 11 extend through the dispersing holes 22a and have upper ends 
fixed to an upper end plate 23 and lower ends fixed to a lower end plate 
24. The upper chamber 21a is enclosed at its upper portion by the upper 
end plate 23, at its side portion by the inner cylinder 21, and at its 
lower portion by the dispersing end plate 22 having the dispersing holes 
22a. A diluted solution 6 flowing in from an absorption device (not shown 
in FIG. 2) temporarily remains in the upper chamber 21a, thus defining a 
dispersing diluted-solution pool 25. The steam generating chamber 3 in the 
inner cylinder 21 is separated from a steam condensing chamber 4 by a 
partition 26 having eliminators 27. Steam condensing heat exchangers 12 
are erected substantially vertically in a space defined between the inner 
cylinder 21 and an outer cylinder 28 and serve as the steam condensing 
chamber 4. Cooling water 10 flows through the pipes of the heat exchanger 
12. 
Operation of the apparatus thus constructed according to the present 
invention is as follows: The diluted solution 6 flowing from the 
absorption chamber (not shown) through a diluted solution inlet pipe 15 
into the dispersing diluted solution pool 25 is dispersed toward the steam 
generating heat exchangers 11 through the dispersing holes 22a at the gaps 
between the dispersing end plate 22 and the steam generating heat 
exchanger 11. The amount of the diluted solution dispersed is dependent on 
the level of the diluted solution 6 in the dispersing diluted solution 
pool 25, that is, the level determined as the influx of the diluted 
solution 6 increases or decreases, and the interval between the dispersing 
holes 22a, the surface roughness, and machining accuracy of the edges of 
the gaps in the dispersing holes 22a. The dispersed diluted solution 6 
flows down the outer pipe surfaces of the heat exchangers 11 into a pool 
of concentrated solution 7 below the steam generating chamber 3. At this 
time, the film of the diluted solution 6 on the outer pipe surfaces of the 
heat exchangers 11 is heated by a hot fluid 5 flowing from a hot fluid 
inlet pipe 13 above the heat exchangers 11 into the latter. The film of 
the diluted solution 6 is vaporized or boiled to generate refrigerant 
steam 8. Therefore, the diluted solution 6 becomes progressively higher in 
concentration as it gives off the refrigerant steam 8, turning into the 
concentrated solution 7 having a prescribed concentration which is fed 
from a concentrated solution outlet pipe 16 into an absorption chamber. 
The hot-fluid 5 is discharged from a lower hot fluid outlet pipe 14. The 
generated refrigerant steam 8 is displaced from the steam generating 
chamber 3 into the steam condensing chamber 4 due to a pressure 
difference, and is cooled by the cooling water 10 flowing through the 
steam condensing heat exchanger 12, condensed on the outer pipe surfaces 
of the heat exchanger 12 into a refrigerant liquid 9 flowing down the 
outer pipe surfaces into a lower refrigerant liquid pool, from which the 
refrigerant liquid 9 is delivered to an evaporation chamber (not shown in 
FIG. 2). 
The eliminators 27 serve to prevent the solution from being scattered into 
the steam condensing chamber 4 due to steam bubbles formed when the 
solution boils on the outer pipe surfaces of the heat exchangers 11. As 
the steam condensing capability is increased, the level of the refrigerant 
liquid 9 in the steam condensing chamber 4 is raised to immerse lower 
portions of the vertical heat exchangers 12 in the refrigerant liquid 9, 
whereupon the surface areas of the heat exchangers 12 available for steam 
condensation are reduced, as is the steam condensing capability. If the 
concentration of the concentrated solution 7 in a lower portion of the 
steam generating chamber 3 becomes higher than a desired level when the 
steam condensing capability is increased, the refrigerant liquid 9 with 
its level increased overflows through gaps in the eliminators 27 into the 
steam generating chamber 3 so that the concentration of the solution 7 
will return to the desired level. Conversely, when the level of the 
refrigerant solution 9 is lowered as the steam condensing capability is 
lowered, the steam condensing heat exchangers 12 have more exposed areas 
emerging from the refrigerant liquid 9. As a result, the steam condensing 
areas are increased to increase the steam condensing capability. 
Therefore, the apparatus is capable of selfadjusting the steam condensing 
capability as the latter is varied. 
Another embodiment of the present invention will be described with 
reference to FIG. 3. Identical or corresponding parts in FIG. 3 are 
denoted by identical or corresponding reference numerals in FIG. 2. A 
cover 29 is attached to a lower end plate 24 for causing a hot fluid 5 
flowing from upper ends of steam generating heat exchangers 11 downwardly 
into the pipes of the heat exchangers 11 to change its direction of flow 
through a flow passage 30 defined by the cover 29 and the lower end plate 
24. The hot fluid 5 then flows upwardly out of the upper ends of the heat 
exchangers 11. With the cover 29 thus attached to the lower end plate 24, 
the steam generating heat exchangers 11 jointly provide a U shape above 
the level of the solution to provide constant surface areas available for 
evaporation. This arrangement solves the problem which would be 
experienced with the above embodiment (FIG. 2) in the case where an 
increase in the steam generating capability in the steam generating 
chamber 3 causes the level of the lower pool of the concentrated solution 
7 to be lowered, increasing the surface areas, and resulting in a further 
increase in the steam generating capability. 
FIGS. 4, 5 and 6 illustrate a steam generating heat exchanger 31 suitable 
for use in the apparatus of the present invention. The heat exchanger has 
tooth-shaped fins 32, 81 to 85 directed at an angle of .theta. with 
respect to a tube 33 of the heat exchanger 1 as shown in FIG. 5. These 
gaps between the adjacent tooth-shaped fins 81 to 85 and between these 
tooth-shaped fins 81 to 85 and the tube 33 allow a diluted solution to 
flow therethrough. As shown in FIGS. 5 and 6, the fins 81 and 84 adjacent 
to each other in an axial direction of the heat exchanger 1 partly overlap 
when viewed in a direction normal to the axis of the heat exchanger 31. 
The angle .theta. is preferably in a range of from 5.degree. to 
50.degree.. 
In operation, when a diluted solution is supplied to the heat exchanger, 
the diluted solution flows down the tube 33 while filling the gaps between 
the axially adjacent tooth-shaped fins 81 and 84. The solution also 
spreads due to capillary action between the circumferentially adjacent 
tooth-shaped fins 81, 82 and 83. Therefore, the solution flows downwardly 
while forming a solution film over all of the heat exchanger 31 as shown 
in FIG. 7. 
Since the tooth-shaped fins 32 present a resistance to the downward flow of 
the solution, the solution 4 flows at a rate less than that at which the 
solution flows in the conventional steam generating apparatus. As a 
result, the fins 32 provide an increased mass transfer rate. 
As the solution is held between the toothshaped fins 81 to 85 due to 
capillary action, the thickness of the solution film surrounding the heat 
exchanger 31 remains substantially constant so that the characteristics of 
the steam generating apparatus are not adversely affected. 
The fins 32 may be of other shapes, and may be arranged regularly or 
irregularly. The fins 32 may be formed by cutting the surface of the heat 
exchanger tube 33 or winding separately prepared teeth 32 as shown in FIG. 
8 around the tube 33.