Abstrict The desiccant assisted air conditioning apparatus can provide a
stable operation and a higher energy efficiency. The apparatus comprises
a process air passage for flowing process air for dehumidification
through a desiccant and for delivery to a conditioning space and
a regeneration air passage for flowing regeneration air for removing
moisture from the desiccant. An absorption heat pump means for providing
cooling heat source for the process air and heating heat source
for the regeneration air is provided which comprises an evaporator,
an absorber, a generator, a condenser and fluid passages therebetween
for forming an absorption refrigeration cycle. The absorption heat
pump means is provided with a heat exchanger in a refrigerant passage
between the condenser and the evaporator for cooling a refrigerant
flowing through the refrigerant passage by heat exchange with a
heat transfer medium.
Claims What is claimed is:
1. A desiccant assisted air conditioning apparatus comprising:
a process air passage flowing process air for dehumidification
through a desiccant and for delivery to a conditioning space;
a regeneration air passage flowing regeneration air for removing
moisture from said desiccant; and
an absorption heat pump means providing a cooling source for said
process air and a heating source for said regeneration air, said
absorption heat pump means having an evaporator, an absorber, a
generator, a condenser and fluid passages therebetween forming an
absorption refrigeration cycle,
wherein said absorption heat pump means includes a heat exchanger
disposed in a refrigerant passage between said condenser and said
evaporator, and flow passage means operative to conduct a heat transfer
medium between said heat exchanger for cooling a refrigerant flowing
through said refrigerant passage and said air conditioning apparatus
for removing moisture from said desiccant.
2. A desiccant assisted air conditioning apparatus according to
claim 1 wherein said heat transfer medium is in a heat exchange
relationship with said regeneration air in said regeneration air
passage for heating said regeneration air.
3. A desiccant assisted air conditioning apparatus according to
claim 1 wherein said heat transfer medium comprises at least a
portion of said regeneration air in said regeneration air passage.
4. A desiccant assisted air conditioning apparatus according to
claim 1 wherein said heat transfer medium is introduced to said
absorber and said condenser so as to be heated therein after exiting
said heat exchanger.
5. A desiccant assisted air conditioning apparatus comprising:
a process air passage flowing process air for dehumidification
through a desiccant and for delivery to a conditioning space;
a regeneration air passage flowing regeneration air for removing
moisture from said desiccant,
an absorption heat pump means providing a cooling source for said
process air and a heating source for said regeneration air, said
absorption heat pump means having an evaporator, an absorber, a
generator, a condenser and fluid passages therebetween forming an
absorption refrigeration cycle,
wherein said absorption heat pump means is provided with a heat
exchanger disposed in a refrigerant passage between said condenser
and said evaporator for cooling a refrigerant flowing through said
refrigerant passage by heat exchange with a heat transfer medium,
and
wherein said heat transfer medium comprises an absorbent fluid
exiting said absorber.
6. A desiccant assisted air conditioning apparatus according to
claim 1 wherein an absorbent fluid in said absorption heat pump
means is an aqueous solution comprising at least of one selected
from the group consisting of sodium hydroxide, potassium hydroxide
and cesium hydroxide, and the refrigerant is water.
7. A desiccant assisted air conditioning apparatus comprising:
a process air passage for flowing process air for dehumidification
through a desiccant and for delivery to a conditioning space;
a regeneration air passage for flowing regeneration air for removing
moisture from said desiccant; and
and absorption heat pump means for providing a cooling source for
said process air and a heating source for said regeneration air,
said absorption heat pump means having an evaporator, an absorber,
a generator, a condenser and fluid passages therebetween forming
an absorption refrigeration cycle,
wherein said absorption heat pump means is provided with a heat
exchanger for exchanging heat between a refrigerant flowing between
said condenser and said evaporator and an absorbent liquid exiting
said absorber for cooling said refrigerant.
8. A desiccant assisted air conditioning apparatus according to
claim 5 wherein an absorbent fluid in said absorption heat pump
means is an aqueous solution comprising at least one selected from
the group consisting of sodium hydroxide, potassium hydroxide and
cesium hydroxide, and the refrigerant is water.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a desiccant assisted air conditioning
apparatus utilizing a heat pump device for desiccant regeneration
and cooling of process air.
2. Description of the Related Art
Desiccant assisted air conditioning apparatus is well known, for
example in a U.S. Pat. No. 2700537. The reference discloses a
desiccant assisted air conditioning apparatus requiring a heat source
of a temperature range of 100-150.degree. C. for regenerating the
desiccant (moisture adsorbent), such as electric heaters or boilers.
In recent years, desiccants which can be regenerated at lower temperatures
in a range of 60-80.degree. C. have been developed so that heat
sources operating at lower temperatures can be utilized.
FIG. 6 is a schematic representation of a typical example of such
improved desiccant assisted apparatus, and FIG. 7 is a psychrometric
chart showing the operation of this example apparatus. In FIG. 6
the reference numeral 101 refers to a conditioning space; 102 refers
to a blower; 103 refers to a desiccant wheel; 104 refers to a sensible
heat exchanger; 105 refers to a humidifier; 106 refers to a water
supply pipe for the humidifier; 107-111 refer to air passages for
conditioned air flows; 130 refers to a blower for the regeneration
air; 120 refers to a heat exchanger between hot water and regeneration
air (hot water heat exchanger); 121 refers to a sensible heat exchanger;
122 123 refer to hot water passages; and 124-129 refer to air passages
for regeneration air. In FIG. 6 circled letters K-V represent thermodynamic
states of the air corresponding to respective sites shown in FIG.
7 SA designates supply air, RA designates return air, OA designates
outside air and EX designates exhaust air.
In the above desiccant assisted air conditioning apparatus, after
dehumidifying the return air (process air) through moisture adsorption
process by flowing it through the desiccant wheel 103 the return
air is cooled by heat exchange with the regeneration air, and is
supplied to the conditioning space. In the meanwhile, outside air
is used as regeneration air, which is heated by a heat transfer
medium of an external heat source (not shown) and is introduced
to the desiccant wheel 103 for regenerating the desiccant wheel
103. The regeneration air is exhausted to the outside environment.
The conditioning space is cooled by repeating the above processes.
One of the alternatives of the above apparatus utilizes exhaust
air from the conditioning room as regeneration air and introduces
the outer air as a process air.
The energy efficiency of such an air conditioning apparatus is
given by a value of coefficient of performance (COP=.DELTA.Q/.DELTA.H)
which is obtained by dividing the enthalpy difference .DELTA.Q (an
indication of cooling effect) shown in FIG. 7 by regeneration heat
.DELTA.H (amount of the regeneration heat). In the conventional
desiccant assisted air conditioning apparatus, even though the temperature
of the hot water required for heating the regeneration air has been
lowered compared with the earlier apparatus, the COP values are
still lower than those of air conditioning apparatus which uses
other thermally driven refrigeration devices, such as a double effect
absorption chiller for cooling and dehumidification of ambient air.
The reason is that, though it is based on a high temperature heat
source of a boiler, the system only utilizes less than one unit
of high quality energy (excergy) out of one unit at temperatures
less than 100.degree. C. for the regeneration of the desiccant.
One of the measures to solve the above problem is an air conditioning
apparatus, as shown in FIG. 8 in which an absorption heat pump
200 in place of a boiler, is provided as a heat source. The heat
recovered from an absorber 1 and a condenser 4 is introduced to
the heater 120 through the heat transfer medium passages 123 42
43 122 and the cooling effect generated in the evaporator 3 is
introduced into a cooler 115 provided in the process air passage
through refrigerant passages 118 53 117. According to the air
conditioning apparatus, a cooling effect due to a sensible heat
exchange between the process air and the regeneration air (.DELTA.Q-.DELTA.q)
can be obtained in addition to the cooling effect (.DELTA.q) of
an absorption heat pump 200 so as to realize a higher energy efficiency
with a more compact construction of the system than the air conditioning
system shown in FIG. 6.
However, in the air conditioning device described above, when an
absorption refrigeration cycle of a so-called single effect type
is used in the absorption heat pump, and a lithium bromide-water
working fluid system is used, if the absorption temperature is set
60-80.degree. C., which is suitable for a heat source of the desiccant
assisted air conditioning apparatus, while the evaporation temperature
is set 10-15.degree. C., which is suitable for cooling temperature
of the process air, then the thermodynamics state of the absorbent
fluid compatible with such liquid temperature and evaporation pressure
condition exceeds a crystallization limit so as to disable the operation
due to crystallization. Also, since the condensation temperature
is raised to 60-80.degree. C., the difference between the temperature
of the condensed refrigerant and the evaporation temperature (10-15.degree.
C.), and, consequently, the difference in enthalpy therebetween
are increased. As a result, the cooling efficiency is much lowered
compared to ordinary absorption chiller, where condensing temperature
is approximately 40.degree. C., due to the self-evaporation of the
refrigerant when it is introduced into the evaporator, so that the
COP value of the heat pump is deteriorated.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to achieve a
desiccant assisted air conditioning apparatus, which can provide
a stable operation and a higher energy efficiency.
According to the invention, a desiccant assisted air conditioning
apparatus comprises: a process air passage for flowing process air
for dehumidification through a desiccant and for delivery to a conditioning
space; a regeneration air passage for flowing regeneration air for
removing moisture from the desiccant; and an absorption heat pump
means for providing a cooling source for the process air and a heating
source for the regeneration air, the absorption heat pump means
having an evaporator, an absorber, a generator, a condenser and
fluid passages therebetween for forming an absorption refrigeration
cycle, wherein the absorption heat pump means is provided with a
heat exchanger in a refrigerant passage between the condenser and
the evaporator for cooling a refrigerant flowing through the refrigerant
passage by heat exchange with a heat transfer medium. According
to the invention, by cooling the refrigerant flowing from the condenser
to the evaporator by the heat exchanger, the loss portion of the
cooling effect due to the self-evaporation of the refrigerant when
flowing into the evaporator is decreased so that a large cooling
effect is produced. Therefore, the cooling effect of the entire
system can be improved to provide a high energy efficiency.
In another aspect of the invention, the heat transfer medium is
in a heat exchange relationship with the regeneration air in the
regeneration air passage for heating the regeneration air. In this
aspect of the invention, the heat transfer medium is provided at
its lowest temperature to the heat exchanger, the efficiency for
cooling the refrigerant is increased, so that the loss of the cooling
efficiency due to the self-evaporation of the refrigerant when flowing
into the evaporator is further decreased. In addition, since the
heat held by the refrigerant itself cane recovered and utilized
for heating the regeneration air, cooling efficiency can be further
improved and a high energy efficiency is obtainable.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of a first embodiment of the
desiccant assisted air conditioning apparatus of the present invention.
FIG. 2 is a Duhring's diagram showing the operational cycles of
the desiccant assisted air conditioning apparatus of the first embodiment.
FIG. 3 is a schematic representation of a second embodiment of
the desiccant assisted air conditioning apparatus of the present
invention.
FIG. 4 is a schematic representation of a third embodiment of the
desiccant assisted air conditioning apparatus of the present invention.
FIG. 5 is a schematic representation of a fourth embodiment of
the desiccant assisted air conditioning apparatus of the present
invention.
FIG. 6 is a schematic representation of a conventional desiccant
assisted air conditioning apparatus.
FIG. 7 is a psychrometric chart of the desiccant assisted air conditioning
apparatus shown in FIG. 6.
FIG. 8 is a schematic representation of a hypothetical desiccant
assisted air conditioning apparatus.
FIG. 9 a psychrometric chart of the conventional desiccant assisted
air conditioning apparatus shown in FIG. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, preferred embodiments of the present invention will
be described in detail. Throughout the specification, the same features
are denoted by the same reference numerals.
A first embodiment of the preferred embodiment will be explained
below with reference to FIGS. 1 to 3. FIG. 1 is a schematic representation
of the basic configuration of the desiccant assisted air conditioning
apparatus of the present invention. The heat pump device section
of the apparatus comprises a circulation unit to provide an absorption
refrigeration cycle including an evaporator 3 an absorber 1 a
generator 2 a condenser 4 and a heat exchanger 5. The heat pump
device section further includes a heat exchanger 7 provided in a
refrigerant passage between the condenser 4 and the evaporator 3
for cooling a refrigerant, and a heat transfer medium (hot water)
passage is provided to flow hot water from a heater 120 of the desiccant
assisted air conditioning apparatus through a pump 150 the heat
exchanger 7 the absorber 1 and condenser 4 to return to the heater
120.
The air conditioning section of the desiccant assisted air conditioning
apparatus shown in FIG. 1 is constructed in the same manner with
that of FIG. 8. A process air passage A is formed as follows: the
conditioning space 101 is communicated with the intake of the blower
102 through the passage 107; the outlet of the blower 102 is communicated
with the desiccant wheel 103 through the passage 108; the discharge
for the process air from the desiccant wheel 103 is communicated
with the sensible heat exchanger 104 which has heat-exchanger relationship
with the regeneration air through the passage 109; the outlet for
the process air from the heat exchanger 104 is communicated with
the chilled water heat exchanger (cooler) 115 through the passage
110; the outlet for the process air from the cooler 115 is communicated
with the humidifier 105 through the passage 119; and the outlet
for the process air from the humidifier 105 is communicated with
the conditioning space 101 through the passage 111; thereby completing
a processing cycle for the process air.
In the meanwhile, the regeneration air passage B is formed as follows:
the external space is communicated with the intake of the blower
130 through the passage 124; the outlet of the blower 130 is communicated
with the sensible heat exchanger 104 heat-exchangeable with the
process air; the outlet for the regeneration air from the sensible
heat exchanger 104 is communicated with the inlet of the low temperature
side of another heat exchanger 121 through a passage 125; the outlet
of the low temperature side of the sensible heat exchanger 121 is
communicated with the hot water heat exchanger 120 through the passage
126; the outlet for the regeneration air of the hot water heat exchanger
120 is communicated with the inlet of the regeneration air of the
desiccant wheel 103 through the passage 127; the outlet for the
regeneration air from the desiccant wheel 103 is connected to the
inlet of the high temperature side of the sensible heat exchanger
121 through the passage 128; the outlet of the high temperature
side of the sensible heat exchanger 121 is communicated with the
external space through the passage 129; thereby completing a regeneration
cycle for introducing and exhausting the outside air.
The hot water inlet of the heater 120 is communicated with the
outlet of the condenser 4 of the absorption heat pump 200 through
the passage 122. The hot water outlet of the heater 120 is communicated
with the inlet of the heat exchanger 7 in the hot water passage
of the absorption heat pump 200 through the passage 123 and the
hot water pump 150.
The chilled water inlet of the cooler 115 is communicated with
the outlet of the evaporator 3 in the chilled water passage of the
absorption heat pump through the passage 117 and the chilled water
outlet of the cooler 115 is communicated with the inlet of the evaporator
3 in the chilled water passage of the absorption heat pump through
the passage 118 and the pump 160. In FIG. 1 the circled alphabetical
designations K-V refer to the thermodynamic states of the air corresponding
to those in FIG. 9 and SA designates supply air, RA designates
return air, OA designates outside air and EX designates exhaust
air.
Next, the absorption cycle of the absorption heat pump section
200 of the desiccant assisted air conditioning system will be explained,
referring to the Duhring's diagram of FIG. 2. One of the absorption
fluids suitable for the absorption heat pump is the one shown in
U.S. Pat. No. 4614605 and "Development of an absorption heat
pump water heater using aqueous ternary hydroxide working fluid
(Int. J. Refrig, 1991 Vol 14 May, p-157), which does not crystallize
in the cycle having a high absorption temperature of 60-80.degree.
C. at an evaporation temperature of 10-15.degree. C. In this art,
the working fluid system is comprised of an aqueous solution including
sodium hydroxide, potassium hydroxide or cesium hydroxide as the
absorbent, and water as the refrigerant. By such a selection of
the working fluids, a refrigeration cycle is formed to provide a
stable operation.
The absorbent fluid is heated to 160-165.degree. C. in the generator
2 by an outer heat source (not shown) through heat transfer pipe
32 to generate a refrigerant vapor (state c) and is condensed, and
is forwarded to the absorber 1 (state d) through the heat exchanger
5. The absorbent fluid absorbs the refrigerant vapor which was evaporated
in the evaporator 3 at 10-15.degree. C. in the absorber 1 and is
diluted (state a), and returns to the generator 2 again through
the heat exchanger (state b) by the function of the pump 6. As the
absorption heat of 67-75.degree. C. generated during the absorption
is generated in the absorber 1 it is possible to transfer the absorption
heat from the absorbent fluid to the heat transfer medium, such
as hot water, through the heat transfer pipe 31. The refrigerant
vapor generated in the generator 2 flows into the condenser 4 to
be condensed (state f) . In the condenser 4 the condensation heat
generated during condensation of the refrigerant vapor is transferred
to the hot water through the heat transfer pipe 34. The condensed
refrigerant is forwarded to the heat exchanger 7 and an orifice
8 and flows into the evaporator 3 to be evaporated. In the evaporator
3 the evaporation heat of 10-15.degree. C. is transferred from
the chilled water by the heat transfer pipe 33. In the heat exchanger
7 the condensed refrigerant of 75-85.degree. C. is cooled by hot
water of 50-60.degree. C. (state g) so that the sensible heat of
the condensed refrigerant can be recovered by the hot water. And
since the enthalpy of the refrigerant at the inlet of the evaporator
3 is reduced, the loss of the cooling effect due to the self-evaporation
of the refrigerant flowing into the evaporator 3 is lowered so that
high degree of cooling effect can be obtained. Also, the COP value
of the heat pump itself is improved, because the required heat input
into the heat pump, i.e. heat input to the generator 2 for conducting
the required heating of the hot water is reduced.
By flowing the heat transfer medium (hot water) from the heat transfer
pipe 31 of the absorber 1 to the heat transfer pipe 34 of the condenser
4 the absorbent fluid temperature becomes lower than the refrigerant
condensation temperature, and concentration of the absorbent fluid
becomes lower than that when the heat transfer medium flows in adverse.
As discussed below, the heat transfer between the air and the hot
water is a sensible heat change process of the air in the desiccant
assisted air conditioning system, and the specific heat of the air
is much lower than that of the water, which means that water is
easily changed in temperature. Therefore, by such an arrangement
of the heat transfer medium passage described above, it is possible
to reduce the hot water flow which may cause a large difference
in the temperature of the hot water, thereby reducing the necessary
driving power for transporting the heat transfer medium.
Next, the operation of the air conditioning apparatus combining
the absorption heat pump device presented above with the desiccant
assisted conditioning section will be explained. Referring to FIG.
1 returning air (process air) from the conditioning room 101 is
withdrawn through the passage 107 into the blower 102 to be pressurized,
and the pressurized air is forwarded to the desiccant wheel 103
through the passage 108 wherein the humidity ratio in the process
air is lowered by having the moisture in the process air removed
by the moisture adsorbent in the desiccant wheel 103. Heat released
during the adsorption process raises the temperature of the process
air. The process air with lower humidity and higher temperature
is forwarded to the sensible heat exchanger 104 through the passage
109 and cooled by heat exchange with the outside air (regeneration
air) . The cooled process air is delivered through the passage 110
to the cooler 115 for further cooling. The cooled process air is
delivered to the humidifier 105 for cooling isenthalpically by water
spray or evaporative humidification, and the cooled process air
is supplied to the conditioning space 101 through the passage 111.
The desiccant material becomes loaded with moisture in the above
process, and it is necessary to be regenerated. In this embodiment,
this is performed by using the outside air as regeneration air as
follows. Outside air (OA) is withdrawn into the blower 130 through
the passage 124 to be pressurized, and the pressurized outside air
is delivered to the sensible heat exchanger 104 to cool the process
air. The regeneration air, having raised its own temperature, is
forwarded to the next sensible heat exchanger 121 through the passage
125 wherein heat exchange takes place with the high temperature
spent regeneration air to further raise its own temperature, and
the regeneration air exiting the sensible heat exchanger 121 flows
into the heater 120 through the passage 126. At this point the temperature
of the regeneration air is raised to 60-80.degree. C. by the hot
water, and its relative humidity is decreased. This process is a
sensible heat change process, and the specific heat of the air is
much lower than that of the water resulting in a large difference
in temperature. Therefore, the heat exchange can be performed efficiently
even when the hot water flowrate is reduced causing a large difference
in temperature, so that the driving power of the hot water can be
reduced. The regeneration air with lower relative humidity exiting
the heater 120 is forwarded to the desiccant wheel 103 to remove
the moisture for regeneration. After passing through the desiccant
wheel 103 the regeneration air flows into the sensible heat exchanger
121 through a passage 128 to preheat the regeneration air, and then
is exhausted as waste to the outside through the passage 129.
The process to this point will be explained with reference to psychrometric
chart in FIG. 9. The air to be processed for the conditioning space
101 (process air: state K) is withdrawn through the passage 107
into the blower 102 to be pressurized, and the pressurized process
air is forwarded to the desiccant wheel 103 through the passage
108. The humidity ratio in the process air is lowered by being adsorbed
of its moisture by the moisture adsorbent in the desiccant wheel
103 and its temperature is raised by absorbing the heat of adsorption
(state L) . The process air, having its humidity lowered and temperature
raised, is delivered to the sensible heat exchanger 104 through
the passage 109 and undergoes heat exchange with outside air (regeneration
air) to lower its temperature (state M) . The cooled process air
is forwarded to the cooler 115 through the passage 110 to be further
cooled (state N). The cooled process air is delivered to the humidifier
105 through the passage 119 and its temperature is lowered isenthalpically
by water spray or evaporative humidification (state P), and the
process air is supplied to the conditioning space 101 through the
passage 111. During the process described above, an enthalpy difference
.DELTA. Q between the return air (state K) and the supply air (state
P) is generated to provide the cooling effect to the conditioning
space 101. According to the embodiment of FIG. 1 as the enthalpy
of the refrigerant at the inlet of the evaporator is lowered and
the refrigerating effect of the heat pump is increased, the enthalpy
difference (.DELTA.q) becomes larger than that of the conventional
art of FIG. 8 and thus the enthalpy difference (.DELTA.Q), which
shows the refrigerating effect, becomes larger.
Regeneration of the desiccant is conducted through the following
steps. Outside air (OA: state Q) for regeneration is withdrawn into
the blower 130 through the passage 124 to be pressurized, and is
delivered to the sensible heat exchanger 104 to cool the process
air while raising its own temperature (state R), and flows into
the next sensible heat exchanger 121 through the passage 125 and,
in exchanging heat with the high temperature spent air, raises its
own temperature (state S). Regeneration air leaving the heat exchanger
121 flows into the heater 120 through the passage 126 so that its
temperature is raised to 60.about.80.degree. C., and its relative
humidity is decreased (state T). Regeneration air having lower relative
humidity passes through the desiccant wheel 103 to remove the moisture
therefrom (state U). Spent air having passed through the desiccant
wheel 103 flows into the sensible heat exchanger 121 through the
passage 128 and preheats regeneration air exiting from the sensible
heat exchanger 104 and lowers its own temperature (state V) . Spent
air is exhausted to outside environment through the passage 129.
The process cycles described above, i.e., regeneration of desiccant
on the one hand and dehumidification and cooling of process air
on the other, is repeatedly carried out to provide desiccant assisted
air conditioning of the conditioning space. It is a common practice
to utilize exhaust air from the conditioning room as regeneration
air, and in this invention also, there is no problem in utilizing
the exhaust room air for regeneration air, and the same result will
be obtained. In this embodiment, the heat transfer medium is introduced
to the heat exchanger 7 to exchange heat with the refrigerant. However,
the heat may be radiated to the outer space to lower the enthalpy
of the refrigerant.
According to the first embodiment of the present invention, since
the heat exchanger 7 is provided in the refrigerant passage from
the condenser to the evaporator, loss of the cooling efficiency
due to the self-evaporation of the refrigerant is lowered, and thus
high degree of refrigeration effect is obtained. Further, the heat
held in the condensed refrigerant, the absorption heat and the condensation
heat can be used as a heat source for heating the regeneration air.
Accordingly, due to the increased cooling performance and improved
COP value of the heat pump, the energy efficiency of the entire
air conditioning system can be improved.
Next, a second embodiment of the preferred embodiment will be explained
below with reference to FIG. 3. According to the second embodiment
of the present invention, a heat exchanger 7 for cooling the refrigerant
is provided in the refrigerant passage from the condenser 4 to the
evaporator 3 so that the hot water from the heater 120 passes the
pump 150 the heat exchanger 7 the condenser 4 and absorber 1
and then returns to the heater 120. According to this embodiment,
the heat transfer medium at its lowest temperature, likewise the
first embodiment, is first introduced into the heat exchanger 7
for cooling the refrigerant through heat exchange therewith, and
then is introduced to the absorber 1 and the condenser 4 to be heated.
Accordingly, the efficiency for cooling the refrigerant is increased,
and the loss of the cooling efficiency due to the self-evaporation
of the refrigerant when flowing into the evaporator is decreased.
Therefore, the cooling effect of the entire system can be improved.
In addition, energy held by the refrigerant can be recovered and
utilized for heating the regeneration air, so that cooling efficiency
can further be improved and high energy efficiency can be provided.
In this embodiment, when the heat transfer medium flows from the
heat transfer pipe 34 of the condenser 4 to the heat transfer pipe
31 of the absorber 1 the absorbing liquid temperature becomes higher
than the refrigerant condensation temperature, resulting in a higher
concentration of the refrigerant in the absorbent fluid than that
when the heat transfer medium flows in adverse. However, there is
not any problem in a practical operation because the higher concentration
of the refrigerant does not result in a crystallization. Moreover,
since the condenser 4 and the heat exchanger 7 are communicated
through both the refrigerant passage and the hot water passage,
the condenser 4 and the heat exchanger 7 can be made integrated
to reduce the production cost. Since the operation of the absorption
heat pump and the desiccant assisted air conditioning system is
substantially the same as that of the first embodiment, detailed
description thereof will be omitted.
Next, a third embodiment of the preferred embodiment will be explained
below with reference to FIG. 4. According to the third embodiment
of the present invention, a heat exchanger 7 for cooling the refrigerant
is provided in the refrigerant passage from the condenser 4 of the
absorption heat pump 200 to the evaporator 1. In this embodiment,
the regeneration air is branched off from the regeneration air passage
B at the point downstream the blower 130 and the upstream the sensible
heat exchanger 104 so that a part of the regeneration air is introduced
to the heat exchanger 7 through a branch passage 151 and the heat-exchanged
air returns to the main passage 125 through a branch passage 152.
According to this embodiment, the refrigerant is cooled by the fresh
regeneration air introduced from outside and at its lowest temperature,
the efficiency for cooling the refrigerant is increased, so that
the loss of the cooling efficiency due to the self-evaporation of
the refrigerant when flowing into the evaporator 3 is decreased.
Therefore, the cooling effect of the entire system can be improved.
In addition, since the heat held by the refrigerant itself can be
recovered and utilized for heating the regeneration air, refrigerating
efficiency can be further improved and high energy efficiency is
obtainable. Since the operation of the absorption heat pump and
the desiccant assisted air conditioning system is substantially
the same as that of the first embodiment, detailed description thereof
will be omitted. In this embodiment, some intermediate heat transfer
medium such as water heat-exchangeable with the regeneration air
can be used for cooling the refrigerant in the heat exchanger 7
instead of using the regeneration air directly.
Next, a fourth embodiment of the preferred embodiment will be explained
below with reference to FIG. 5. According to the embodiment, a heat
exchanger 7 for cooling the refrigerant is also provided in the
refrigerant passage from the condenser 4 to the evaporator 3 in
the absorption heat pump 200. In this embodiment, a heat transfer
passage 21 is provided to introduce the absorbent fluid exiting
the absorber 1 to the heat exchanger 7 to exchange heat with the
refrigerant flowing from the condenser 4 to the evaporator 3 the
absorbent fluid after heat exchange is then introduced to the heat
exchanger 5 and to the generator 2. According to this embodiment,
since the absorbent fluid at its lowest temperature is introduced
to the heat exchanger 7 to cool the refrigerant, the efficiency
for cooling the refrigerant is increased, and the loss of the cooling
efficiency due to the self-evaporation of the refrigerant when flowing
into the evaporator 3 is decreased. Therefore, the cooling effect
of the entire system can be improved. In addition, since the heat
of the condensed refrigerant is recovered into the absorbent fluid
system, the required heat input into the heat pump, i.e. heat input
to the generator 2 for conducting the required heating of the hot
water is reduced so as to provide an improved COP value of the heat
pump as well as a high energy efficiency. Since the operation of
the absorption heat pump and the desiccant assisted air conditioning
system is substantially the same as that of the first embodiment,
detailed description thereof will be omitted.
Although the foregoing embodiments were illustrated in terms of
understanding, and should not be construed to limit the scope of
the present invention. |