Absorption refrigerator

An absorption refrigerator includes a generator for separating, by vaporization, a refrigerant from an absorption solution, a condenser for liquefying by condensation the vaporized refrigerant, an evaporator for vaporizing the liquefied refrigerant from the condenser by heat exchange with a heat medium, and an absorber for absorbing the vaporized refrigerant to react against the absorption solution to be supplied from the generator. The evaporator has heat exchanger pipes disposed in the vertical direction and refrigerant discharge nozzles for discharging the refrigerant toward the inner walls of the heat exchanger pipes. Each of the refrigerant discharge nozzles is arranged at a position displaced downward by a predetermined distance from the upper end of each of the heat exchanger pipes.

BACKGROUND OF THE INVENTION 
The present invention relates to an absorption refrigerator for use with an 
air conditioner, a water heater, etc. 
This type of absorption refrigerator is disclosed in Japanese Patent 
Application No. 7-292,756/1985. The structure of this absorption 
refrigerator is as shown in FIG. 7 wherein reference numeral 1 designates 
the absorption refrigerator as proposed. This absorption refrigerator 1 
comprises a generator 2 which has a regeneration function for heating a 
diluted absorption solution B which has absorbed a heat exchanger 
refrigerant A and separates the refrigerant A from the absorption solution 
B by vaporization, and a function for separating absorption solution from 
vaporized refrigerant. Further, the absorption refrigerator 1 comprises a 
condenser 3 for liquefying the separated vaporized refrigerant A through 
condensation, an evaporator 4 into which the liquefied refrigerant A 
discharged from the condenser 3 is supplied and which is adapted to 
vaporize the liquefied refrigerant A by depriving a heat medium C such as 
the outside air and the like contacting the outer surface thereof of its 
latent heat of vaporization and an absorber 5 for allowing the vaporized 
refrigerant A to be absorbed in absorption solution B by causing the 
vaporized refrigerant A from the evaporator to react against the 
absorption solution B which has been condensed after the refrigerant A was 
vaporized and supplied from the generator 2 and for circulating the 
absorption solution B, which has absorbed the refrigerant A, through the 
generator 2. 
The generator 2 is provided with a cylindrical rectifying tower 6, a 
regenerator 8 directly connected to the lower part of a rectifying tower 6 
and provided with a burner 7 as a heating portion for heating the 
absorption solution B which has absorbed the refrigerant A (the absorption 
solution B that has absorbed the refrigerant A is hereinafter called a 
diluted absorption solution D), a diluted absorption solution spraying 
nozzle 9 provided substantially at the central portion of the rectifying 
tower 6 and adapted to spray the diluted absorption solution D into the 
rectifying tower 6, a filler material 10 such as a non-woven fabric 
disposed above the regenerator 8, and an auxiliary condenser 11 arranged 
near the upper end of the filler material 10 within the rectifying tower 6 
and adapted to cool and condense the refrigerant A when the refrigerant A, 
which has been vaporized to become separated from the diluted absorption 
solution D by being heated by the burner 7, has reached the upper portion 
of the rectifying tower 6. 
The condenser 3 is arranged substantially parallel to the rectifying tower 
6 and comprises a storage box 13 held in communication with the downstream 
side end of the auxiliary condenser 11 through a duct 12, a refrigerant 
tank 14 arranged below the storage box 13 in spaced apart relationship 
with the latter, a plurality of communication pipes 15 for establishing 
communication between the storage box 13 and the refrigerant tank 14, an 
outer sheath 17 provided to surround the communication pipes 15 and to 
form a cooling water path 16 between the storage box 13 and the 
refrigerant tank 14. 
The condenser 3 guides the refrigerant A flowing into the storage box 13 
via the auxiliary condenser 11 to the refrigerant tank 14 through the 
communication pipes 15 and, during its passage through the pipes 15, the 
refrigerant A is condensed and liquefied by cooling water E (to be 
described later) flowing in the cooling water path 16 between the 
communication pipes 15. 
The evaporator 4 comprises a plurality of heat exchanger pipes 18 disposed 
along the vertical direction, an upper header 19 for connecting the upper 
ends of the heat exchanger pipes 18 so as to establish communication 
therebetween, a lower header 20 for connecting the lower ends of the heat 
exchanger pipes 18 so as to establish communication therebetween and a 
number of heat exchanger fins 21 arranged along the longitudinal direction 
of the heat exchanger pipes 18 in spaced apart relationships with one 
another and to which the heat exchanger pipes 18 are fixed, keeping 
communication therebetween. Further, each of the upper ends of the heat 
exchanger pipes 18 is held in communication with the refrigerant tank 14 
through a refrigerant supply pipe 22, the upper header 19 is held in 
communication with the upper end of the absorber 5 through a communication 
pipe 23 and the lower header 20 is held in communication with the diluted 
absorption solution tank 24 provided at the lower end of the absorber 5 
through a communication pipe 25. Further, between the downstream side end 
of the refrigerant supply pipe 22 and the upper end of each of the heat 
exchanger pipes 18 of the evaporator 4, there is provided a refrigerant 
dripping means 26 for distributing the liquefied refrigerant A from the 
refrigerant supply pipe 22 to the heat exchanger pipes 18 so as to allow 
the refrigerant A to drip along the inner surfaces of the heat exchanger 
pipes 18. 
As shown in FIGS. 8 and 9, the refrigerant dripping means 26 comprises a 
refrigerant supply header 27 arranged along the upper end of the heat 
exchanger pipes 18, a refrigerant supply nozzle 28 provided on the 
refrigerant supply header 27 in spaced apart relationship with the latter 
so as to project into the interior of the heat exchanger pipe 18 and a 
guide member 29 provided within the upper end of the heat exchanger pipe 
18 and adapted to drop the liquefied refrigerant A from the refrigerant 
supply nozzle 28 along the inner wall surface of the heat exchanger pipe 
18. 
Described in more detail, the upper end of the heat exchanger pipe 18 has, 
as shown in FIG. 9, a large-diameter portion 18a and the upper header 19 
is connected airtight to the large-diameter portion 18a so as to cover an 
open end of portion 18a. Further, at the position of the upper header 19 
that is opposed to a small-diameter portion 18b of the heat exchanger pipe 
18, there is formed a through hole 19a which establishes communication 
between the heat exchanger pipe 18 and the upper header 19 and annular 
guide member 29 of substantially the same diameter as the through hole 19a 
is mounted so as to establish communication between the through hole 19a 
and the small diameter portion 18b of the heat exchanger pipe 18. 
The guide member 29 has the upper end thereof connected airtight to the 
upper header 19 while the lower end thereof is fitted in the 
small-diameter portion 18b of the heat exchanger pipe 18 so that by the 
existence of the large-diameter portion 18a of the heat exchanger pipe 18, 
there is formed a stay portion 18c for the liquefied refrigerant A between 
the guide member 29 and the upper header 19 and within this stay portion 
18c, the top end of the supply nozzle 28 passing through the side wall of 
the large-diameter portion 18a of the heat exchanger pipe 18 is 
positioned. 
Further, at the lower end of the guide member 29 there are formed a number 
of guide grooves 30 along the direction of axis of the guide member so as 
to open toward the lower end surface of the guide member and to extend to 
a predetermined depth from that lower end surface, and through such guide 
grooves 30, the above-mentioned stay portion 18c is held in communication 
with the interior of the heat exchanger pipe 18. 
The absorber 5 comprises an absorption solution dripping means 31 to which 
there is connected the communication pipe 23 which is connected to the 
upper header 19 of the evaporator, the diluted absorption solution tank 24 
arranged below the absorption solution dripping means in spaced apart 
relationship with the latter and in which the absorption solution B (i.e., 
the diluted absorption solution D) which has absorbed the refrigerant as a 
result of its reaction against the vaporized refrigerant A is stored, a 
plurality of communication pipes 32 for establishing communication between 
the absorption solution dripping means 31 and the diluted absorption 
solution tank 24 and an outer sheath 34 provided to surround the 
communication pipes 32 so as to form a cooling water path 33 between the 
absorption solution dripping means and the diluted absorption solution 
tank 24 and adapted to absorb the refrigerant A vaporized in heat 
exchanger pipes 18 by reducing the internal pressure thereof. 
Further, the absorption solution dripping means 31 has its upper portion 
connected to an absorption solution supply pipe 35 for supplying 
absorption solution B condensed by the regenerator 8 and is provided 
therein with a dispersion plate 36 disposed to divide the inner space 
thereof vertically into two portions. Further, the above-mentioned 
communication pipe 23 is connected to dripping means 31 at a position 
below the dispersion plate 36 and through this communication pipe 23 the 
refrigerant A vaporized by the evaporator 4 is supplied. 
The diluted absorption solution tank 24 is held in communication with the 
diluted absorption solution spray nozzle 9 through a diluted absorption 
solution return pipe 37 and at the intermediate portion of the return pipe 
37 there is provided a diluted absorption solution circulation pump 38 for 
supplying the diluted absorption solution stored in the diluted absorption 
solution tank 24 to the diluted absorption solution spray nozzle 9. 
Between the upper end of the outer sheath 34 of the absorber 5 and the 
lower end of the outer sheath 17 of the condenser 3 there is provided a 
communication pipe 39 to thereby establish communication therebetween, and 
between the upper end of the outer sheath 17 and the auxiliary condenser 
11 there is provided a communication pipe 40 to thereby establish 
communication therebetween. Further, between the auxiliary condenser 11 
and the lower end of the outer sheath 34 there is provided a communication 
pipe 41 to thereby establish communication therebetween and a closed 
circuit for the circulation of cooling water is formed by the outer sheath 
34, the communication pipe 39, the outer sheath 17, the connecting pipe 
40, the auxiliary condenser 11 and the communication pipe 41. At the 
intermediate portion of the communication pipe 41, there are provided an 
air conditioner room unit 42 and a cooling water circulation pump 43 for 
circulating the cooling water E. 
In FIG. 7, reference numeral 44 designates a refrigerant circulation pump 
provided midway in the refrigerant supply pipe 22 so as to supply the 
liquefied refrigerant A, reference numeral 45 designates a heat exchanger 
into which the absorption solution supply pipe 35 and the diluted 
absorption solution return pipe 37 are inserted so as to exchange heat 
between the two pipes and supplying C to the reference numeral 46 
designates an air blower for supplying the outside air as an outside heat 
medium C to the evaporator 4. 
In the case of the absorption refrigerator 1 of the above-described 
structure, the liquefied refrigerant A supplied from the refrigerant tank 
14 by means of the refrigerant circulation pump 44 is supplied to the 
refrigerant dripping means 26 provided above the evaporator 4. 
In the refrigerant dripping means 26, the liquefied refrigerant A is 
distributed to the stay portion 18c through the refrigerant supply header 
27 and each of the refrigerant supply nozzles 28. Then, the liquefied 
refrigerant A supplied to the stay portion 18c is dripped to flow down 
along the inner wall surface of each heat exchanger pipe 18 and by the 
contact of the outside air as the heat medium C with the surfaces of the 
heat exchanger fins 21 and the heat exchanger pipe 18, a heat exchange 
operation is performed between the open air C and the liquefied 
refrigerant A flowing downward along the inner wall surfaces of the heat 
exchanger pipes 18, so that the liquefied refrigerant A vaporizes by 
depriving the outside air C of its latent heat of vaporization, moves 
upward within the heat exchanger pipes 18 and after being collected by the 
upper header 19 at the upper end of the heat exchanger pipes 18, it is 
supplied to the absorber 5. 
The vaporized refrigerant A supplied to the absorber 5 is, brought into 
contact with the absorption solution B from the regenerator 8 so that it 
is absorbed into the absorption. solution B to become the diluted 
absorption solution D. Further, the diluted absorption solution D is 
supplied to the diluted absorption solution spray nozzle 9 through the 
diluted. absorption circulation pump 38 so as to be sprayed into the 
rectifying tower 6, heated by the burner 7 under the rectifying tower 6 
and with the vaporization of the refrigerant A, the diluted absorption 
solution D is separated into the absorption solution B and the refrigerant 
A. 
Thus, the refrigerant A exchanges heat with the cooling water E during its 
passage through the auxiliary condenser 11 and the condenser 3 and 
further, during its passage through the absorber 5, the heat it has 
absorbed from the outside air is given to the cooling water E. 
Accordingly, the cooling water E is gradually heated while it is circulated 
through the absorber 5, the condenser 3 and the auxiliary condenser 11 and 
then supplied to the ,air conditioner room unit 42 for heating. 
In the case of the absorption refrigerator 1, it is possible to increase 
the amount of heat radiation from the room unit 42 by more than 1.3 times 
the amount of heat generated from the burner 7 by help heating the cooling 
water E through the absorption of the heat energy of the outside air C. 
PROBLEMS SOUGHT TO BE SOLVED BY THE INVENTION 
In the case of the absorber 5, the vaporized refrigerant A within the heat 
exchanger pipes 18 is sucked from the upper end of the pipes 18 into the 
absorber 5 by reducing the internal pressure of the absorber 5 and since 
the pressure within the heat exchanger pipes 18 tends to increase due to 
vaporization of the refrigerant A, an air current directed to the absorber 
5 from the lower end thereof via the upper end thereof is generated within 
the heat exchanger pipes 18. 
The evaporator 4 is so constructed that the liquefied refrigerant A is 
dripped down along the inner wall surfaces of the heat exchanger pipes 18 
from the upper end thereof but when the amount of vaporization of the 
refrigerant A is large, it is supposed that since the pressure in the heat 
exchanger pipes 18 increases gradually and the velocity of the air current 
is accelerated, the refrigerant A dripped on the upper ends of the heat 
exchanger pipes 18 will be supplied to the absorber 5 by the air current 
before vaporization of the refrigerant resulting in reducing the heat 
absorption efficiency of the refrigerant in the evaporator 4. 
In addition, due to the arrangement in which the refrigerant A is dripped 
through the guide grooves 30 formed below the stay portion 18c after it is 
once stored in the stay portion 18c, the amount of dripping is liable to 
be affected by the variation of pressure within the heat exchanger pipe 18 
and there is sometimes a case in which the amount of dripping of the 
refrigerant A scatters to a great degree. 
SUMMARY OF THE INVENTION 
The present invention has been made in view of the problems involved in the 
above-described proposal. 
A first object of the present invention is to provide an absorption 
refrigerator which can increase the rate of vaporization of a refrigerant 
discharged into the heat exchanger pipes of the absorption refrigerator. 
A second object of the present invention is to provide an absorption 
refrigerator which can control as much as possible the amount of discharge 
of the refrigerant. 
Now, in the case of the absorption refrigerator shown in FIG. 7, dew 
condensation takes place on the surfaces of the heat exchanger fins 21 of 
the evaporator 4 and waterdrops sometimes adhere to the surfaces of the 
fins 21 and in the case of the evaporator 4 of the above-described 
absorption refrigerator 1, there is the problem that the above-mentioned 
waterdrops stay on the surfaces of the heat exchanger fins 21. 
Thus, if the waterdrops have stayed on the surfaces of the heat transfer 
fins 21, the transfer of heat at the portion where the waterdrops are 
hindered so that the heat exchange efficiency of the evaporator 4 lowers 
resulting in affecting the heat exchange efficiency of the absorption 
refrigerator. 
Further, if the waterdrops have stayed on the surfaces of the heat 
exchanger fins 21 due to the cooling of the heat exchanger fins 21 by 
vaporization of the low temperature refrigerant, the waterdrops sometimes 
freeze and the adhesion of the waterdrops to the heat exchanger fins 21 is 
further accelerated by this freezing so that not only it becomes difficult 
to remove them but also the frozen portion develops to narrow the flow 
path of the heat medium generated among the heat exchanger fins 21 
resulting in increasing the flow path resistance which further lowers the 
heat exchange efficiency between the outside air C and the heat exchanger 
fins 21. 
In addition, there is also the problem that the flow of the outside air C 
becomes parallel to the heat exchanger fins 21 and the flow of the outside 
air among the heat exchanger fins 21 becomes a lamination flow so that a 
thin laminar flow boundary layer is formed on the surfaces of the fins 21 
whereby the amount of heat transfer between the outside air and the heat 
exchanger fins 21 is reduced. 
Accordingly, still another object of the present invention is to prevent 
the lowering of the heat exchange efficiency between the heat exchanger 
fins of the evaporator and the heat medium. 
In order to achieve the above-described first object of the present 
invention, an absorption refrigerator according to a first of the 
invention comprises a generator provided with a heating portion for 
heating an absorption solution which has absorbed a heat exchanging 
refrigerant and separating the refrigerant by vaporization from the 
absorption solution, a condenser for condensing and liquefying the 
separated vaporized refrigerant, an evaporator into which the liquefied 
refrigerant from the condenser is supplied and which is adapted to 
vaporize the refrigerant by heat exchange with a heat medium brought into 
contact with the outer surface thereof and an absorber for allowing the 
refrigerant to be absorbed in the by causing the vaporized refrigerant 
supplied from the evaporator to react against the absorption solution from 
the rectifier and for circulating the absorption solution which has 
absorbed the refrigerant therein, through the generator. The evaporator is 
provided with heat exchanger pipes disposed vertically and refrigerant 
discharge nozzles discharging the liquefied refrigerant toward the inner 
wall of each of the heat exchanger pipes, with a nozzle being provided at 
a position displaced downward by a predetermined distance from the upper 
end of each of the heat exchanger pipes. 
As a second feature of the present invention proposed to invention, achieve 
the above-described first object of the invention, there is provided an 
absorption refrigerator which comprises a generator provided with a 
heating portion for heating an absorption solution which has absorbed a 
heat exchange refrigerant and separating the refrigerant from the 
absorption solution by vaporization, a condenser for condensing and 
liquefying the separated vaporized refrigerant, an evaporator into which 
the liquefied refrigerant from the condenser is supplied and which is 
adapted to vaporize the refrigerant by heat exchange with a heat medium 
caused to be brought into contact with the outer surface thereof and an 
absorber for allowing the refrigerant to be absorbed in the absorption 
solution by causing the vaporized refrigerant supplied from the evaporator 
and the absorption solution from the generator to react with each other 
and for circulating the absorption solution, which has absorbed the 
refrigerant therein, through the generator. The evaporator is provided 
with heat exchanger pipes disposed vertically and refrigerant discharge 
nozzles each having a refrigerant discharge hole for discharging the 
liquefied refrigerant toward the inner wall of each of the heat exchanger 
pipes with the refrigerant discharge nozzle hole being provided at a 
position displaced downward by a predetermined distance from the upper end 
of each of the heat exchanger pipes and held opposite to the inner wall of 
the heat exchanger pipe leaving a space of about less than 5 mm from the 
latter. 
Further, an absorption refrigerator according to a third feature of the 
present invention is so constructed that in order to achieve the 
above-described second object of the present invention, the refrigerant 
discharge nozzle in the apparatus according to the first feature is 
directly connected to one end of a U-shaped pipe projecting outwardly of 
the lower portion of each of the heat exchanger pipes and to the other end 
of the U-shaped pipe there is connected a refrigerant tank for storing the 
liquefied refrigerant supplied from the condenser in such a manner that 
the level of the refrigerant stored in the tank is held higher than each 
of the refrigerant discharge nozzles. 
An absorption refrigerator according to a fourth feature of the present 
invention comprises a generator provided with a heating portion for 
heating an absorption solution which has absorbed a heat exchanging 
refrigerant so as to separate the refrigerant from the absorption 
solution, an evaporator for vaporizing the refrigerant by heat exchange 
with a heat medium caused to be brought into contact with the outer 
surface thereof, and an absorber for allowing the refrigerant to be 
absorbed in the absorption solution by causing the vaporized refrigerant 
supplied from the evaporator and the absorption solution supplied from the 
generator to react with each other and for circulating the absorption 
solution, which has absorbed the refrigerant therein, through the 
generator. The evaporator is provided with heat transfer pipes erected 
upright, and a number of heat transfer fins are attached to the outer 
surfaces of the heat exchanger pipes in spaced apart relationship with one 
another. 
An absorption refrigerator according to a fifth feature of the present 
invention has the structure such that in the structure of the fourth 
feature of the invention, the angle of inclination of each of the heat 
exchanger fins with respect to the horizontal plane is set to an angular 
range of 15.degree.-50.degree.. 
An absorption refrigerator according to a sixth feature of the present 
invention has a structure such that in the structure of the fourth feature 
of the invention, each of the heat exchanger fins is provided with a 
plurality of slits extending upward from the lower edge thereof in spaced 
apart relationship with one another along that lower edge. 
An absorption refrigerator according to a seventh feature of the invention 
has the structure such that in the structure of the sixth feature, the 
slits formed with the heat exchanger fins are positioned so as to overlap 
vertically. 
An absorption refrigerator according to an eighth feature of the present 
invention has the structure such that in the structure of the sixth 
feature of the invention, the edge portion@, forming the slits of the heat 
exchanger fins are bent to bulge downward.

BEST MODES FOR CARRYING OUT THE INVENTION 
A preferred embodiment of the present invention will now be described with 
reference to FIGS. 1 through 5. 
It is noted that throughout the description that follows, like parts are 
designated by like reference numerals with respect to FIGS. 7 through 9. 
In FIG. 1, reference numeral 50 designates an absorption refrigerator 
according to this mode and comprises a generator 2 provided with a heating 
portion for separating the refrigerant from an absorption solution B 
(diluted absorption solution D) by vaporization, a condenser 51 for 
condensing and liquefying the separated vaporized refrigerant, an 
evaporator 52 into which the liquefied refrigerant A discharged from the 
condenser 51 is supplied and which is adapted to vaporize the liquefied 
refrigerant A through its heat exchange with the outside air C coming into 
contact with the outer surface thereof and an absorber 5 for allowing the 
absorption solution B to absorb the refrigerant A therein by causing the 
vaporized refrigerant A from the evaporator 52 to react against the 
absorption solution B from the generator 2 and for circulating the 
absorption solution B (i.e., the diluted absorption solution D), which has 
absorbed the refrigerant A therein, through the generator 2, wherein the 
evaporator 52 is provided with a plurality of heat exchanger pipes 18 
erected upright and a plurality of refrigerant discharge nozzles 53 for 
discharging the liquefied refrigerant A toward the inner walls of the heat 
exchanger pipes 18, respectively, and each of the refrigerant discharge 
nozzles 53 is provided at a position displaced downward by a predetermined 
distance from the upper end of each of the heat exchanger pipes 18. 
As shown in FIG. 3, the refrigerant discharge nozzle 53 is provided with a 
refrigerant discharge hole 53a for discharging the liquefied refrigerant A 
toward the inner wall of the heat exchanger pipe 18 at a position 
displaced downward by a predetermined distance from the upper end of the 
heat exchanger pipe 18 and is held in a spaced confronting relation with 
the inner wall surface of the heat exchanger pipe 18 leaving a gap (g) of 
less than about 5 mm from the latter. 
Next, to describe the above-mentioned elements in more detail, in the 
instant mode, the condenser 51 is made to communicate with a cooling water 
path 33 of the absorber 5 and a cooling water circulation system is 
constructed with communication pipe 40 and a communication pipe 41 for 
establishing communication between the cooling water path 33 and the room 
unit 42. 
Further, to the downstream side of the condenser 51, there is connected a 
refrigerant tank 54 for storing the refrigerant A which has been condensed 
and liquefied by the condenser 51, and a refrigerant flow-out portion of 
the refrigerant tank 54 is connected the refrigerant discharge nozzle 53 
through a U-shaped pipe 55, which will be described presently. 
The refrigerant discharge nozzle 53 is directly connected to one end of the 
U-shaped pipe 55 projecting from the lower portion of the heat exchanger 
pipe 18 and the refrigerant tank 54 is directly connected to the other end 
of the U-shaped pipe 55 so that the liquefied refrigerant A stored in the 
refrigerant tank 54 is supplied to the refrigerant discharge nozzle 53 
through the U-shaped pipe 55 due to a siphon phenomenon. 
Further, a U-shaped pipe 55 is provided for each heat transfer pipe 18 and 
the above-mentioned refrigerant discharge nozzle 53 is integrally formed 
therewith. Further, it comprises a plurality of discharge pipes 55a 
projecting outside the heat exchanger pipes 18, a distribution header 55b 
for establishing communication among the discharge pipes 55a and a 
communication pipe 55c for establishing communication between the 
distribution header 55b and the refrigerant tank 54 and when viewed as a 
whole, it is in the shape of downwardly curved letter-U. 
Further, as shown in FIG. 2, the refrigerant discharge nozzle 53 is located 
at a position displaced downward from the upper end of the heat exchanger 
pipe 18 by a predetermined distance (in the instant mode, at substantially 
the intermediate portion of the length of the heat exchanger pipe 18) and 
the lower end of the refrigerant tank 54 is positioned higher than the 
refrigerant discharge nozzle 53 so that the level of the liquefied 
refrigerant A stored therein is always kept at a position above the 
refrigerant discharge nozzle 53. 
The reason why the refrigerant discharge nozzle 53 is provided at the 
position displaced downward from the upper end of the heat exchanger pipe 
18 by a predetermined distance is that by causing the liquefied 
refrigerant A to be discharged toward the inner wall surface of 
substantially the intermediate portion of the length of the 
upright-erected heat exchanger pipe 18, even when the unvaporized liquid 
drop-like refrigerant A has been carried toward the upper portion of the 
heat exchanger pipe 18, that is, the downstream side, the liquid drop-like 
refrigerant A is stopped before it reaches the upper end of the heat 
exchanger pipe 18 and is caused to adhere to the inner wall of the heat 
exchanger pipe 18 so that in the course of its falling thereafter, the 
liquid drop-like refrigerant A is vaporized by its heat exchange with the 
outside air C through the wall of the heat exchanger pipe 18. 
Such a phenomenon can be realized in such a manner liquefied that a main 
vaporization region for the liquefied refrigerant A is provided below the 
intermediate portion of the heat exchanger pipe 18 so that the amount of 
vaporization at the region above the intermediate portion is made small to 
thereby reduce the pressure within the heat exchanger pipe 18 and by this 
pressure reduction, the flow velocity of the air current within the heat 
exchanger pipe 18 is delayed. 
Accordingly, the supply of the unvaporized refrigerant A into the absorber 
5 is controlled to increase the amount of vaporization of the refrigerant 
A within the heat exchanger pipe 18. 
Further, the reason why the refrigerant discharge nozzle 53 and the 
refrigerant tank 54 are connected through the U-shaped pipe and the 
refrigerant tank 54 is positioned higher than the refrigerant discharge 
nozzle 53 is that by so doing, the portion between both of the members 
(53, 54) is always kept in a liquid-sealed state and the influence of the 
variation of the pressure within the heat exchanger pipe 18 on the 
liquefied refrigerant A within the refrigerant tank 54 is controlled. The 
supply pressure of the refrigerant A with respect to each of the 
refrigerant discharge nozzles 53 provided for each of the heat exchanger 
pipes 18 is made constant by making it equal to the head pressure 
difference between the refrigerant discharge nozzle 53 and the refrigerant 
tank 54 so that by the synergistic action based on these arrangements, the 
amount of discharge of the refrigerant A from each of the nozzles 53 is 
made uniform especially in a state in which the refrigerant discharge 
current is small. By performing the supply of the refrigerant A based on 
the head pressure difference, the refrigerant circulation pump 44 which 
has hitherto been required (FIG. 7) can be omitted. 
Further, as shown in FIGS. 3 and 4, on the side wall of the refrigerant 
discharge nozzle 53 near the top end thereof, there is formed refrigerant 
discharge hole 53a opening-toward the inner wall surface of the heat 
exchanger pipe 18. Since the top end of the nozzle 53 is provided adjacent 
to the inner wall surface of the heat exchanger pipe 18, the refrigerant 
discharge hole 53a is held opposite to the inner wall surface of the heat 
exchanger pipe 18 leaving a gap (g) of less than a predetermined distance 
therebetween. 
The size of the gap (g) is dependent on the viscosity and temperature of 
the refrigerant being used but in the ordinary range of use, it is less 
than about 5 mm. 
The reason why the gap g is less than about 5 mm is that when the liquefied 
refrigerant A is discharged toward the inner wall of the heat exchanger 
pipe 18 from the refrigerant discharge hole 53a, the liquefied refrigerant 
A is retained between the refrigerant discharge nozzle 53 and to its the 
inner wall of the heat exchanger pipe 18 due to its surface tension. 
Thereby for example, when a rising air current within the heat exchanger 
pipe 18 is large, the unvaporized refrigerant A is prevented from being 
sucked upward by making the surface tension maximum while when the rising 
air current is small, and the refrigerant A discharged from the 
refrigerant discharge hole 53a is prevented from falling along the outer 
surface of the refrigerant discharge pipe 53. 
The liquefied refrigerant A falling along the outer surface of the 
refrigerant discharge pipe 53 is not made use of since it is never 
vaporized and it never deprives the outside air C of its latent heat of 
vaporization. 
Further, as shown in FIG. 3, on the inner wall surface of the heat 
exchanger pipe 18 there is formed a helical groove R of a very fine depth 
(this may be knurling tool-like irregularities) over the entire inner wall 
surface of the heat exchanger pipe 18. Due to the capillary action of this 
helical groove R, the liquefied refrigerant A adheres to the inner wall 
surface of the heat exchanger pipe 18 in a favorable manner and, it 
expands along that inner wall surface with the result that smooth 
vaporization of the liquefied refrigerant A is performed. 
On the other hand, as shown in FIGS. 2 and 3, the heat exchanger fins 21 
mounted on the outer peripheral surface of the heat exchanger pipe 18 are 
provided in numbers at predetermined. intervals in the longitudinal 
direction of the heat exchanger pipe 18. Each of these heat exchanger fins 
21 is arranged aslant with respect to the horizontal plane with the 
formation of a boss 21a which is brought into contact with the surface of 
the heat exchanger pipe 18. As shown in FIG. 3, the heat exchanger pipe 18 
is inserted into the boss. 
The angle of inclination of the heat exchanger fin 21 is so set that, as 
shown in FIG. 3, the downstream side of the direction of flow of the 
outside air C which is brought into contact with the surface of the heat 
exchanger pipe 18 is the lower side of the fin 21. Further, the boss 21a 
itself forms a heat transfer surface between the heat exchanger fin 21 and 
the heat exchanger pipe 18 and is brought into contact with the downwardly 
located heat exchanger fin 21 to thereby keep constant the space between 
the fins 21. 
The reason why the heat exchanger fin 21 is inclined is that when the 
surface of the heat exchanger pipe 18 and that of the exchanger fin 21 are 
covered with condensation, depending on the temperature or humidity of the 
environment in which it is used, the resultant waterdrops are introduced 
toward the downstream side by the inclined heat exchanger fin 21 to cause 
them to fall down from the lower edge of the fin 21. Thus, the waterdrops 
are prevented from staying on the surface of the fin 21, the flow of the 
outside air C is prevented from being hindered and reduction of the heat 
exchange area of the heat exchanger fin 21 is prevented. 
When the waterdrops are forced to stay on the heat exchanger fin 21, they 
begin to freeze depending on the condition of the outside air and the flow 
path of the outside air C formed among all the fins 21 is narrowed to 
further lower the heat exchange efficiency so that it is necessary to 
remove the waterdrops by causing them to fall down at an early stage. 
Further, due to the inclination of the heat exchanger fin 21 with respect 
to the flow of the outside air C, the flow of the outside air C becomes 
turbulent on the side of the upper surface of the heat exchanger fin 21 
near the upstream end of the fin as shown by X in FIG. 3, whereby the 
outside air C flowing on the surface of the fin 21 is agitated, thereby 
increasing the heat exchange efficiency between the heat exchanger fin 21 
and the outside air C. 
The angle .alpha. of inclination of the heat exchanger fin 21 is desired to 
be in the range of 15.degree.-50.degree.. 
The reason why the angle .alpha. of inclination of the heat exchanger fin 
21 is set to the above-mentioned range is that if the angle .alpha. is 
less than 15.degree., the adhesion of waterdrops to the heat exchanger fin 
21 due to the surface tension of the water drops is strong so that the 
separation of the waterdrops from the surface of the fin 21 is not made 
smoothly, while if it exceeds 50.degree., the flow path of the outside air 
formed among all the heat exchanger fins 21 is narrowed due to the flow 
path being forced to curve rapidly, resulting in that ventilation of the 
evaporator 52 itself is spoiled to thereby lower the heat exchanger 
efficiency of the evaporator. 
In addition, in the instant mode, at a portion of the edge of each heat 
exchanger fin 21 located between every adjoining two heat exchanger pipes 
18, there is formed a slit 56 of a predetermined depth from that edge of 
the fin 21 (FIG. 5). 
This slit 56 is formed to have a depth of about 10 mm and a width of about 
4 mm, for example. The reason why slit 56 is formed is that there are 
formed projecting edges at the points of intersection of both vertical 
side edges 56a of the slit 56 and the lower edge of the heat exchanger fin 
21 and these projecting edges act as a trigger for breaking the adhesive 
power of waterdrops H of the refrigerant A based on the surface tension of 
the waterdrops so that the falling down of the waterdrops is accelerated. 
Further, the slits 56 formed in the heat exchanger fins 21 are respectively 
made to overlap one another in the vertical direction so that a waterdrop 
H falling from any of the slits 56 of the upper heat exchanger fin 21 runs 
against another waterdrop H at the corresponding slit 56 of the lower heat 
exchanger fin 21 or joins together to grow in size to thereby accelerate 
the falling of the waterdrops. 
Still further, where the slits 56 are formed in each of the heat exchanger 
fins 21, since the lower edge of each heat exchanger fin 21 is divided 
into portions corresponding to the heat exchanger pipes 18, respectively, 
if the lower edges of these portions are curved downward to form curved 
surfaces at the slits 56 as shown in FIG. 6, it becomes possible to force 
the waterdrops H adhering to the surface of each heat exchanger fin 21 to 
roll down toward the slits 56 along the curved surfaces so that the 
falling of the waterdrops H is further accelerated. 
In the case of the above-described absorption refrigerator 50, since the 
heat exchanger fins 21 are attached aslant to each of the heat exchanger 
pipes 18, when the surface of the heat exchanger pipe 18 or the surface of 
each of the heat exchanger fins 21 is covered with condensation, the 
resultant waterdrops H are introduced toward the downstream side due to 
the inclination of the fin 21 and then forced to fall down from the lower 
edge thereof. 
Further, even when the waterdrops stay on the heat exchanger fin 21 without 
separating from the lower edge thereof due to surface tension, the 
waterdrops themselves gradually collect and grow to a mass whereupon such 
mass of waterdrops extends along the edge of the heat exchanger fin 21 to 
reach the edges of slits 56 and when it comes into contact with the 
projecting edge formed at the points of intersection of the vertical side 
edges 56a of the slit 56 and the heat exchanger fin 21, the balance of the 
surface tension of the waterdrop mass is lost and with this phenomenon 
acting as a trigger, a part of the waterdrop mass is separated from the 
heat exchanger fin 21. 
Thus, when the balance of the surface tension of the waterdrop mass is lost 
at a part of the mass and the waterdrop mass begins to fall down, that 
part of the mass is also forced to fall down in sequence from the heat 
exchanger fin 21. 
In the case of the absorption refrigerator so according to the instant 
mode, where the liquefied refrigerant A is vaporized to absorb heat from 
the outside air, since the liquefied refrigerant A is discharged toward 
the inner wall surface of substantially the intermediate portion of the 
length of the heat exchanger pipe 18 which is upright, even when the 
refrigerant A in the form of unvaporized liquid drops is carried upward, 
that is, the downstream side of the heat exchanger pipe 18, the amount of 
vaporization of the refrigerant A in the upper portion of the heat 
exchanger pipe 18 is small. Thus, the internal pressure is comparatively 
low so that the liquid drop-like refrigerant A stops moving upward before 
it reaches the upper end of the heat exchanger pipe 18, adheres to the 
inner wall of the pipe 18, begins to move down and in the course of its 
downward movement, is vaporized as a result of its heat exchange with the 
open air C through the wall of the pipe 18. 
Consequently, the supply of the unvaporized refrigerant A to the absorber 5 
is controlled to increase the amount of vaporization of the refrigerant A 
in the heat exchanger pipe 18 thereby enhancing the heat exchanger 
efficiency of the evaporator 52. 
In addition, due to the fact that the above-mentioned refrigerant discharge 
hole 53a is held opposite to the inner wall of the heat exchanger pipe 18 
leaving a gap g of less than about 5 mm, the liquefied refrigerant A 
discharged from the refrigerant discharge hole 53a is retained between the 
refrigerant discharge nozzle 53 and the inner wall surface of the heat 
exchanger pipe 18 by maximum surface tension. When the amount of the 
rising air current in the heat exchanger pipe 18 is large, the unvaporized 
refrigerant A is prevented from being sucked upward while when the amount 
of the rising air current is small, the refrigerant A discharged from that 
hole 53a is prevented from falling down along the outer surface of the 
refrigerant discharge pipe 53. 
Accordingly, from this point of view, the amount of vaporization of the 
liquefied refrigerant A is secured to thereby increase the heat exchange 
efficiency of the evaporator 52. 
At the same time, in the instant mode of the invention, due to the fact 
that the refrigerant discharge nozzle 53 and the refrigerant tank 54 for 
supplying the liquefied refrigerant A to the nozzle 53 are held in 
communication with each other through the U-shaped pipe 55 and the 
refrigerant tank 54 is positioned higher than the refrigerant discharge 
nozzle 53, the portion between the two elements is always liquid-sealed. 
Thus, the influence of the variation of pressure in the heat exchanger 
pipe 18 on the liquefied refrigerant A in the refrigerant tank 54 is 
controlled. Since the refrigerant supply pressure with respect to each of 
the refrigerant discharge nozzles 53 provided in correspondence to each of 
the heat exchanger pipes 18 is kept substantially constant based on the 
head pressure difference resulting from the difference of elevation 
between the nozzle 53 and the tank 54, the discharge amount of the 
refrigerant A from each of the discharge nozzles 53 is made uniform due to 
a synergistic action of these factors especially when the amount of 
discharge is not large. 
Further, since the supply of the refrigerant A is based on the head 
pressure difference, the provision of the refrigerant circulation pump 44 
(FIG. 7) which has hitherto been required is no longer necessary. This 
results in facilitating miniaturization and reduction of manufacturing 
costs. 
Further, it should be noted that the various shapes and combinations of the 
composite members shown in the above-described mode are only an example 
and that various modifications based on design requirements are possible. 
For example, although, in the above-described mode, an example is shown in 
which the refrigerant tank 54 is positioned higher than the refrigerant 
discharge nozzle 53 to save the use of the refrigerant circulation pump 
44, it is also possible to arrange the refrigerant tank 54 below the 
refrigerant discharge nozzle 53 as usual and the refrigerant A is supplied 
to the nozzle 53 by refrigerant circulation pump 44. 
In the above case, however, it is estimated that the supply of the 
refrigerant A becomes irregular due to pulsation of the refrigerant 
circulation pump 44 but the effect of increasing the amount of 
vaporization can be achieved to a sufficient degree by arrangement of the 
refrigerant discharge nozzle 53 at a position displaced downward from the 
upper end of each of the heat exchanger pipe 18. 
As regards the position of installation of the refrigerant discharge nozzle 
53 with respect to the heat exchanger pipe 18, it is not always limited to 
the intermediate portion of the length of the heat exchanger pipe 18 so 
that it is possible to adjust the position in the vertical direction based 
on the velocity of the air current in the heat exchanger pipe 18. 
Further, although the structure is shown with each of the heat exchanger 
fins 21 inclined, the removal of waterdrops from the fin 21 may be 
facilitated by the provision of slits in horizontal fins. 
Further, in the case of absorption refrigerator 50 according to the present 
invention, each of the heat exchanger fins 21 is attached aslant to each 
of the heat exchanger pipes 18 so that when the surface of the heat 
exchanger pipe 18 or the heat exchanger fin 21 is covered with 
condensation, the resultant waterdrops H are introduced toward the 
downstream side and then forced to fall down from the lower edge of the 
fin 21. 
Consequently, waterdrops generated due to the above-mentioned condensation 
are prevented from staying on the surface of the heat exchanger fin 21 to 
thereby prevent such disadvantages as obstruction to the flow of the 
outside air C, the reduction of the heat exchange area of the heat 
exchanger fin 21 and the reduction of the area of the refrigerant flow 
path due to freezing of the waterdrops. 
Still further, since the heat exchanger fin 21 is made inclined with 
respect to the flow of the heat medium, the flow of the outside air C 
along the surface of the heat exchanger fin 21 becomes turbulent so that 
the outside air C is agitated resulting in enhancing its heat exchange 
efficiency with the heat exchanger fin 21. Further, since the angle 
.alpha. of inclination of the heat exchanger fin 21 is set to the range of 
15.degree.-50.degree., the waterdrops are moved smoothly to secure their 
separation from the surface of the heat exchanger fin 21 and at the same 
time, heat exchange between the outside air C and the heat exchanger fin 
21 is performed in a favorable manner. 
Consequently, the lowering of the heat exchange efficiency of the 
evaporator 52 is prevented and the thermal efficiency of the absorption 
refrigerator as a whole is enhanced. 
In the above-described mode, the shapes and combinations of component parts 
of the apparatus given therein are only shown as an example but various 
modifications may be made possible. For example, the refrigerant A may be 
discharged from the upper end of each heat exchanger pipe 18 as usual and 
the formation of slits 56 for each heat exchanger fin 21 may be omitted. 
As described above, in the absorption refrigerator according to a first 
feature of the present invention, when the refrigerant is vaporized in the 
evaporator to absorb heat from the heat medium, even in a case where the 
liquefied refrigerant is discharged toward the inner wall surface of the 
heat exchanger pipe at a position displaced by a predetermined distance 
from the upper end of the heat exchanger pipe so that the unvaporized 
liquid drop-like refrigerant scatters toward the upper portion of the heat 
exchanger pipe due to the air current within the pipe, the refrigerant 
stops moving upward so as to adhere to the inner wall of the pipe before 
it reaches the upper end of the pipe and then begins to fall down in the 
course of which the refrigerant is vaporized as a result of its heat 
exchange with the heat medium through the wall of the pipe. 
Accordingly, the unvaporized refrigerant is inhibited from being supplied 
to the absorber to increase the amount of vaporization of the refrigerant 
within the heat exchanger pipe which results in enhancing the heat 
exchange efficiency of the evaporator. 
Moreover, according to a second feature of the present invention, the 
refrigerant discharge hole is held opposite to the inner wall surface of 
the heat exchanger pipe 18 leaving a gap g of about less than 5 mm from 
the latter so that the liquefied refrigerant discharged from the 
refrigerant discharge hole is retained between the refrigerant discharge 
nozzle and the inner wall surface of the heat exchanger pipe with the 
maximum surface tension. Thus, when the amount of the rising air current 
within the heat exchanger pipe is large, the liquefied refrigerant is 
prevented from being sucked upward while when small, the liquefied 
refrigerant discharged from the refrigerant discharge nozzle is prevented 
from falling down along the outer surface of the nozzle. 
Accordingly, it is possible to secure the amount of vaporization by making 
the liquefied refrigerant adapted to the inner wall of the heat exchanger 
pipe to thereby enhance the heat exchange efficiency of the evaporator. 
Further, in the absorption refrigerator according a third feature of the 
present invention, the refrigerant discharge nozzle and the refrigerant 
tank from which the liquefied refrigerant is supplied to the nozzle are 
made to communicate with each other through the U-shaped pipe and the and 
the refrigerant tank is positioned higher than the nozzle. Thus, the 
portion between both elements is always kept liquid-sealed with the 
refrigerant and the influence of the variation of the pressure in the heat 
exchanger pipe on the refrigerant in the U-shaped pipe is controlled. 
Further, the supply of the refrigerant to the refrigerant discharge nozzle 
is performed on the basis of the head pressure difference resulting from 
the difference of elevation between the nozzle and the refrigerant tank so 
that the refrigerant supply pressure is kept substantially constant. Due 
to a synergistic action of these arrangements, it is possible to make the 
discharge amount of the refrigerant from the refrigerant discharge nozzle 
as uniform as possible especially when the discharge amount is not large. 
Still further, by supplying the refrigerant on the basis of the head 
pressure difference, the refrigerant circulation pump which has hitherto 
been required is no longer necessary and it is possible to make compact 
the apparatus and to reduce the manufacturing cost thereof. 
In the absorption refrigerator according to a fourth feature of the present 
invention, each of the heat exchanger fins to be attached to the outer 
surfaces of heat exchanger pipes of the evaporator is inclined with 
respect to the flow of the heat medium with the downstream side of the fin 
being held lower than the upstream side thereof, so that even when 
waterdrops generating as a result of condensation adhere to the surface of 
the heat exchanger fin, such waterdrops can be moved to the lower portion 
of the fin to force them to fall down from the lower edge of the fin. 
Consequently, the reduction of the heat transfer area of each of the heat 
exchanger fins due to the presence of the waterdrops and also the 
reduction of the width of the flow path of the heat medium between the 
heat exchanger fins can be prevented which results in preventing the 
lowering of the heat exchange efficiency of the evaporator. 
According to a fifth feature of the present invention, the angle .alpha. of 
inclination of the heat exchanger fin 21 is set to the range of 
15.degree.-50.degree. so that while controlling the increase of the 
resistance in the heat medium flow path, the smooth movement of the 
waterdrops on the heat exchanger fin is secured to thereby further 
increase the efficiency of heat exchange between the heat medium and the 
heat exchanger fin. 
In the absorption refrigerator according to a sixth feature of the present 
invention, each of the heat exchanger fins to be attached to the outer 
surfaces of the heat exchanger pipes of the evaporator is inclined with 
respect to the flow of the heat medium with the downstream side of the fin 
being lower than the upstream side so that even when waterdrops generating 
as a result of condensation adhere to the surface of the heat exchanger 
fin, the waterdrops can be removed by allowing them to naturally move 
downward and to fall down from the lower edge of the fin. 
Further, in the above case, even when the waterdrops stay at the lower edge 
of the heat exchanger fin due to their surface tension, they reach slits 
formed at the lower edge of the fins as they grow. At these slits, surface 
tension is lost by the presence of projecting edges formed at the points 
of intersection of the lower edge of the heat exchanger fin and the 
vertical side edges of the slits so that it is possible to remove the 
waterdrops without fail by forcing them to fall down. 
Consequently, the reduction of the heat exchange area of the heat exchanger 
fin due to the presence of waterdrops and the reduction of the width of 
the flow path of the heat medium can be prevented thereby preventing the 
lowering of the heat exchange efficiency of the evaporator. 
According to a seventh feature of the present invention, the slits of the 
heat exchanger fins are respectively overlapped in the vertical direction 
such that the waterdrops falling down from the slits of the uppermost heat 
exchanger fin are caused to run against those adhering to the slit 
portions of the lower heat exchanger fins in sequence or allowing the 
waterdrops to gather together to form a mass, thereby accelerating the 
removal of the lower waterdrops. 
Lastly, according to an eighth feature of the present invention, the edges 
of the heat exchanger fins are bent upward among the slits, respectively, 
so that the waterdrops adhering to the heat exchanger fins are forced to 
move toward the slits thereby effectively performing waterdrop separating 
and removing operations through the slits.