Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1~557~1
This invention relates to air conditioning and more
particularly to a method and apparatus for controlling the
humidity and the temperature of ai:r through the use of solar
energy.
The desirability of utillzing solar energy has been
recogniz~d. Solar energy collectors have been produced from
sheets of aluminum laminated one to another, each sheet having
a raised portion extending from end-to-end thereof, and matchina
a raised portion on the other sheet, so that the laminate has a
char.nel extending from end-to-end through which a heat transfer
fluid, usually water, can be circulated. Such a collector can
be positioned so that solar radiation is intercepted by a major ~ -
surface thereof, and a heat transfer fluid can be circulated
through the collector channel to be heated by the intercepted
solar energy. The temperature to which the heat transfer fluid
is heated can be varied, within limits, by controlling the rate
at which it is circulated thxough the collector. Howe~er, the
temperature to which the heat transfer fluid is heated varies
as an inverse function of the flow rate, and, it has been
found, the amount of energy available from any given collector
also varies as an inverse functlon of the discharge temperature ;~
of the heat transfer fluid. Por example, slightly less than
70 percent as much energy is available from a g.iven collector~
when the discharge temperature of the heat transfer fluid~
having a rela-tively low~flow rate is 200F. as when the
discharge temperature of the fluld at a higher flow rate~ls~
14QF., other factors being eqoal.~
The use of energy;~from a solar collector~in
~,~ absorption refrigeration apparatus~has been suggested. It~has~;
~ 30 been found that available absorption refrigeration apparatus
- can be operated on energy from;~a solar collector,~prov1ded
that the collector~ls operated~to~provlde~a~heat transfer
.
105~7~
fluid at a temperature of at least about 200F., but that the
absorption refrigeration appara-tus will have approximately
50 percent of the capacity for which it was designed. It will
be appreciated, therefore, that there is a need ffor more
efficient ways to utilize energy from solar collectors.
According to the present invention, apparatus is
provided for conditioning air through a more efficient use of
solar energy than that found in the prior art. Either a mixture
of fresh air and return air or fresh air only is dehumidified by
passing the air through a contactor where it comes in contact
with a hygroscopic solution of a glycol. In the latter case
the dehumidified fresh air only is mixed with the return air.
In either case the resultant mixture is further chilled to the
extent necessary and it is delivered to a closed air conditioned
space. Dehumidification of the outside air component
considerably reduces the energy requirements for cooling the
mixed air to a desired temperature level.
Solar energy absorbed by a solar collector is
transferred into a heat storage tank by means of a liqu1d and
is used for regenerating the hygroscopic solution used in the
contactor. Dilute hygroscopic solut1on from the contaFtor is~ ~
circulated to a regenerator where it~is concentrated and the
: .
concentrated~solution is returned to the contactor. At least ;
some of the dilute hygroscopic solution circulated to the ~
regenerator is also circulated~through a heat exchange~oo~ n;
a storage tank containing a l1qui~d heated with solar enérgy~to
.~ maintain a desired temperature of~the hygroscopic~solut1on~
during regenerat1on, e.g , 130F. to 150F. for a~g1ycol
solution.
30 ~ ~ ~ Energy~stored in the tank may also be used for
energizing absorption refrigerat1on apparatus which 1n~cludes~
a generator; a condenser~and an e~aporator. The energy is
'1~55~0~L
used to heat refrigerant in the generator. The condenser may be connected,
in place of the heat exchange coil in the solar energy storage tank, to heat
the hygroscopic solution which is being concentrated in the regenerator.
Either the evaporator or an evaporative cooler may be used for cooling the
concentrated hygroscopic solution circulated through the contactor during
dehumidification to increase the efficiem~y of dehumidification in the
contactor and to lower the temperature of the dehumidified air leaving the
contactor. In addition, either the evaporative cooler or the evaporator of
the absorption refrigeration apparatus may be operatively connected to a
heat exchanger for cooling dehumidified fresh air or a mixture of the de-
humidified fresh air and return air. Since the moisture content of the
air has been greatly reduced by the dehumidifier, the energy required to
cool the air to a desired level also will be reduced significantly.
It is an object of the invention to provide air conditioning
apparatus which uses solar energy as an energy source for regenerating a
hygroscopic solution of a glycol used to dehumidify air.
Another object of the invention is to provide air conditioning
apparatus in which solar energy is used both for operating absorption re-
frigeration apparatus and for regenerating a hygroscopic solution of a glycol `
used in a dehumidifier.
Still another object of the invention is to provide air condition- -
ing apparatus in which solar energy is used both for operating refrigeration -
apparatus driven by a rankine cycle engine and for regenerating a hygroscopic
solution of a glycol used in a dehumidifier. -
According to a broad aspect of the present invention, there is
provided apparatus for conditioning air comprising, in combination, a con-
tactor, means for circulating air to be conditioned to said contactor in
contact with an aqueous hygroscopic solution, a hygroscopic solution regener-
ator, means for circulating a concentrated hygroscopic solution from said
3~ re~ene~ator to said contactor, means for circulating a dilute hygroscopic ~-
solution from said contactor to said regenerator, means for circulating
regenerating air through said regenerator in contact with the hygroscopic
,,~
-3- ~
,~
1~5~7~1
.... .... .
solution therein whereby such solution is concentrated, a solar collector,
means for transferring heat from said solar collector to the hygroscopic
solution being regenerated in said regenerator, an absorption refrigerator
including a generator and an evaporator, means for transferring heat from
said solar collector to said generator, a heat exchange coil located in said
evaporator to be cooled by refrigerant, and means for removing heat from
the hygroscopic solution which contacts air circulated through said contactor
including means for circulating a controlled portion of the hygroscopic
solution in said contactor through said heat exchange coil.
Other objects and advantages of the invention will become apparent
from the following detailed description with reference being made to the . -
accompanying drawings. ~ ~
''.' '`- .:,
~',.
' ''`
~ .
.: -3a-
55701.
Fig. 1 is a partially schematic diagram o~ air
conditioning apparatus according to the invention, and including
a solar collector, an energy storage tank, and a chemical
dehumidifier;
Fig. 2 is a psychometric chart illustrating one way
of operating the apparatus of Fig. li
Fig. 3 is a partially schematic diagram of air
conditioning apparatus according to the invention, and including
a solar collector, an energy storage tank, a chemical
dehumidifier and a~sorption refrigeration apparatus;
Fig. 4 is a psychometric chart illustrating one way
of operating the apparatus of Fig. 3;
Fig. S is a partially schematic diagram of air
conditioning apparatus according to the invention, and -
including a solar collector, an energy storage tank, a chemical
dehumidifier and refrigeration apparatus of the compressor-
condenser-evaporator type driven by a rankine cycle~engine;
Fig. 6 is a schematic diagram of air conditioning
apparatus according to the present invention in which a
desiccant from a chemical dehumidifier is regenerated with
both solar energy and waste energy from a diesel engine which
drives an air conditioner compressor; and
Fig. 7 is a schematic diagram of air conditioning
apparatus according to the present lnvention in which a liquid
desiccant in a first dehumidification stage is regenerated~
with solar energy and a dry desiccant in a second
dehumidification stage is regenerated with waste heat from a
diesel engine which drives an air conditioner compressor.
Referring to Fig. 1 of the drawings, air conditioning
.
30 apparatus according to the invention is shown as comprisinq a --
solar collector 10, a heated water storage tank 11, and
dehumidification apparatus including a contactor 12 and~a
~5~701
regenerator 13. A heat transfer fluid, usually -treated water,
is circulated from the tank 11 through a line 14 to a pump 15,
and from thence through a line 16 to -the solar collector 10.
Heated Eluid returns from the collector 10 throu~h a line 17
to the tank 11. The pump 15 is controlled to maintain a
predetermined fluid temperature, say, 1~0F., within the tank 11.
As will be discussed in greater detail below, fresh
air is dehumidified by drawing the air through a spray of an -
aqueous hygroscopic solution of a glycol in the contactor 12.
10 The hygroscopic solution is recirculated through the contactor 12 ~
from a collection reservoir located at the bottom of the : :
contactor 12. A portion of the solution in the reservoir is `
also circulated through the regenerator 13 where it is
concentrated by evaporating water from the solution~ .
Concentrated solution is returned from the regenerator 13 to the :
contactor 12.
The aqueous hygroscopic solution is circulated by a `~
pump 18 through a line 19, an indirect heat exchanger 20 and a .
line 21 to the regenerator 13. The concentrated solution is
then returned by a pump 22 through a line 23, the indirect
heat exchanger 20, and a line 24 back into a reservoir in the
contactor 12. The glycol solution is also circulated by a
pump 25 from the regenerator 13 through a line 26 to a heat
exchange coil 27 positioned withln the tank 11 where the
solution is heated, and thence through a line 28 to spray
nozzles 29 within the regenerator;13. Preheated alr, as
subsequently explained, enters the regenerator 13 at the upper
left, travels downwardly wit.h the:heated glycol solution :
sprayed from the nozzles 29, past a baffle 31, and then
3Q upwardly through the blower 30 to be discharged from the system
~ along with water evaporated from the heated glycol solution.
; The regenerator 13 can be controlled~conveniently by~ utiliæing
.: :
:';''
1G15570~
a by-pass 32, under the control of a valve 33 to maintain the
temperature of the glycol solution leaving the nozzles 29 at a
predetermined control level. ~Iygroscopic glycol solutions are
available, for example, for which a predetermined controlled
temperature on the order of 120F. to 130F. is sufficient to
evaporate the water from the solution.
The hygroscopic glycol solution is also circulated
from the reservoir in the contactor 12 by a pump 34 through a
three-way valve 35 and a line 36 to a coil 37 of an evaporative
cooler or cooling tower 38. The cooling tower 38 transfers to
a heat sink, the atmosphere, heat of sorption from the
dehumidification process. "Heat of sorption" may be defined
as a change from latent heat to sensible heat including the
latent heat of condensation oE water vapor and any heat of
solution resulting from the mixin~ of the water removed from
the dehumidified air with the glycol solution, or other
hygroscopic material. The cooled glycol solution from the
coil 37 flows through a line 39 and is sprayed from nozzles 40
within the contactor 12. Fresh air is drawn into the
contactor 12 by a blower 41, is dehumidified and, usualIy,
cooled sensibly, by contact with the glycol solution sprayed
from the nozzles 40. The contactor 12 can be controlled by --
~ using a by-pass 42, under the control of a valve 43 to maintain
- a predetermined dry bulb temperature at the inlet to the
blower 41.
It will be apparent from the above description that
the contactor 12 requires a cooled glycol solution while thé ~ -
regenerator 13 requires a heated soIution. The warm
concentrated solution pumped from the regenerator 13 to the ~ -
contactor 12 is therefore passed through the heat exchanger 20
where some of the unwanted heat in the concentrated solution is
transferred to the cool dllute solution being pumped from the
.:
:
~5570~
contactor 12 to the re~enera-tor 13. Thus, the heat exchanger 20
increases the efficiency of -the dehumidification apparatus.
Conditioned air leaves the contactor 12 in a duct 44
where it is mixed with return air in a duct 45 of a conventional
air distribution system (not illustrated). The mixture of -
dehumidified fresh air and return air flows from the duct 44
through an indirect heat exchanger 46 and into a duct 47, from
which it is delivered to the air distribution system. Or, the
duct 45 may be connected to mix the return and fresh air prior `
to dehumidi~ication in the contactor 12. In the indirect heat
exchanger 46 the mixture of dehumidified fresh air and return
air is cooled sensibly by contact with an indirect heat exchange
coil 48 through which chilled water from a conventional source
(not illustrated) is circulated as required to maintain a
desired dry bulb temperature in the duct 47.
As previously indicated, -the air entering the left
side of the regenerator 13 is pre-heated. This can be
accomplished by delivering the regenerating air, preferably
relief air from the building being conditioned, through a
line 49 to an indirect air-to-air heat exchanger 50. Hot,
saturated air within the regenerator 13 flows through the
opposite side of the indirect heat~exchanger 50 before enterlng
the blower 30 for discharge~from the regenerator 13. In a
practical situation, building exhaust air in the line 49~may
,
have a dry bulb temperature of~about 83F. and a dew point of
: .
~ about 56F., while air enterlng the heat exchanger 50 from thè ~ -
i regenerator 13 may be saturated at 120F. Under these
conditions, sufficient heat transfer is possible in the
indirect heat exchanger 50 that the ultimate exhaust air can
leave the blower 30 at a;dry bulb temperature of 96F. and a
dew point of 79F.; this heat transfer reduces significantly~the
energy required for regeneration of the hygroscopic glycol
solution.
~7~
5S~70~
Referring to Fig. ~ of the drawings, the psychometric
chart illustrates a preferred mode o~ operating the apparatus of
Fig. l~ Outside air entering the contactor 12 having a dry
bulb temperature of 92F. and a wet bulb temperature of 76F.,
point A, is dehumidified and cooled, and then enters the duct 44
at a dry bulb temperature of 85F. and a wet bulb temperature
of 48F., point B, and is mixed with 6-l/2 times its weight of
return air having a dry bulb temperature of 81F. and a wet
bulb temperature of 56F., point C. The mixture has a dry
bulb temperature of 82F. and a wet bulb temperature of 55F.,
point D. The mixture can be cooled sensibly in the indirect
heat exchanger 46 to a dry bulb temperature of 63F. without
changing its wet bulb temperature, point E, and will be heated
to a dry bulb temperature of about 67F., point F, in the
building distribution system (not illustrated), so that it can
be used as required to maintain a control condition: dry bulb
temperature 76F. and wet bulb temperature 56F, point G. It
has been found that the apparatus of Fig. l, when operated as
just described, requires about 3.2 tons of refrigeration for the - -
indirect heat exchanger 46 and 1 ton of refrigeration for the
chemical dehumidifier to condition a given number of pounds of
air per hour as described. If, for purposes of comparison, but
not in accordance with the lnstant invention, air is conditioned
at the same given rate, but by mixing outside air and return
.
air, and coollng and dehumidifylng this mixture by means of a
chilled, indirect heat exchange coil, it is found that: tl) the
mixture has to be chilled tu a dry bulb temperature of about
58F. to achieve the required dehumidification; (2) the mlxture,
~: :
~ after dehumidi~ication must be reheated to about 67F.; and
:
~3) the energy requirement,~for~cooling, dehumidifying and ~ -
reheating, is equivalent to about 4.8 tons of refrigerationO
8-
11~55~0'1
In so~e instances, the solar collector 10 will collect
insufficient heat for regenerating the hygroscopic glycol
solution. For example, on certain hot, humid days, heavy cloud
cover may limit the solar energy intercepted by the collector 10.
Additional energy will also be required if the apparatus is
operated at night. A steam or other heat source 51 may be
connected to a coil 52 located to heat water in the storage
tank 11 during such conditions. In many cities, large office
buildings are heated during cold weather with steam purchased
from a utility company such as an electric company. The steam,
which may be a by-product from the utility company, is also
available in the summer and may be used when necessary for
heating water in the tank 11 to provide sufficient energy for
operating the regenerator 13.
Referring, now, to Fig. 3, air conditioning apparatus
is shown according to a second embodiment of the invention.
The apparatus generally comprises a collector 60 for solar
energy, a storage tank 61 for heated heat transfer fluid,
dehumidification apparatus including a contactor 62 and a
regenerator 63, and absorption refrigeration apparatus shown
schematically as includiny a generator 64, a condenser 65, an
evaporator 66 and an absorber and heat exchanger 67. ~A heat
transfer fluid, usually treated water, is circulated from the
tank 61 through a line 68 by a pump 69, and thence through a
line 70 to the~solar collector 60~. Heated fluid returns from
the collector 60 through a line 71 to the tank 61. The pump 69
:
`~ is controlled to maintain a predetermined fluid temperature,
~ for example, 200F., within the-tank 61. In the event that ~ -
,~ energy intercepted by the solar colleetor is insuf~lclent to ~ -
~, -
heat the fluid in the tank 61 ;to the predetermined temperature,
the fluid may be heated from an auxiliary steam source 72
: ~ - : .-
connected to a heat exchanger coil 73 in the tank 61 or by any ~
other convenient~means. -
:
.
_9_
1~57~
An aqueous hygroscopic solution of a glycol is
circulated by a pump 74 from a reservoir in the contactor 62
through a line 75, an indirect heat exchanger 76 and a line 77
to the regenerator 63 for concentration, while the concentrated
solution is circulated by a pump 78 through a line 79, the
indirect heat exchanger 76, and a line gO back to the contactor
62. The glycol solution is also circulated by a pump 81 from
the regenerator 63 through a line 82 and a heat exchange coil
83 positioned within the condenser 65 wherein the fluid is
heated, and thence through a line 84 and spray nozzles 85
within the regenerator 63. Three-way valves 86 and 87 may also
be provided in the lines 82 and 84, respectively, for
selectively circulating at least a portion of the fluid through
a heat exchange coil 88 in the solar energy storage tank 61 in
place of the condenser 65. This enables heating the glycol
solution for regeneration directly from the solar energy
storage tank when the absorption refrigeration apparatus is not
in use. The heated glycol solution is regenerated by air drawn
into the regenerator 63 by a blower 89 and through an indirect
heat exchanger 90. The air, preferably building exhaust air,
travels downwardly on the left side of the regenerator 63 with ~ -
glycol solution sprayed from the nozzles 85, laterally to the
right, and then upwardly through the indirect heat exchanger 90
and the blower 89 to be discharged from the system along with
water vaporized from the heated glycol solution. The
regenerator 63 can be controlled conveniently by utilizing a
by--pass 91, under the control of a valve 92, to maintain the
:
- temperature of the glycol solution;leaving the nozzles 85 at a~
predetermined control temperature. It will be noted;that the
indirect heat exchanger 76 heats the~dilute glycol~solution
~ flowing from the contactor 62 to the regenerator 63 while --~
;~ simultaneously cooling the concentrated glycol solution flowing
''~ ' : - 1 0-- ,
557~L
from the regenerator 63 to the contactor 62, thereby increasiny
the efficiency of the dehumidification apparatus.
The glycol solution can be circulated from the
contactor 62 by a pump 93 through a three-way valve 94 and a
line 95 to a heat exchange coil 96 in an evaporative cooler or
cooling tower 97. Cooled glycol solution from the coil 96 can
flow through a line 98 and a valve 99, and be sprayed from
nozzles 100 within the contac-tor 62. Either fresh air or a
mixture of fresh and return air is drawn into the contactor 62
by a blower 101, and is dehumidified and, usually, cooled
sensibly, by contact with the glycol solution being sprayed
from the nozzles 100. The contactor 62 can be controlled by
using a by-pass 102 under the control of a valve 103, to
maintain a predetermined dry bulb temperature at the inlet to
the blower 101. Operation of the apparatus of Fig. 3 as
described, i.e., using the evaporative cooler 97 to remove heat
from the glycol solution, as required, to maintain the
predetermined dry bulb temperature at the inlet to the
blower 101 is preferred when the outside wet bulb temperature -
20 is comparatively low. When the outside wet bulb temperature `
is higher, the valves 94 and 99 can be set to circulate at
least a portion of the glycol solution through a heat exchange
coil 104 in the evaporator 66 of the absorption refrigeration
apparatus. As is subsequently explained in more~detai~l, this
constitutes a particularly advantageous way to operate the~
apparatus of Fig. 3. ~ - -
;
The absorption refrigeration apparatus is of a
conventional design. A heat exchange coil 105 in the 9torage ~ -
tank 61 is connected to supply~heated heat transfer flu1d to a
~ -
30 heat exchange coil 106 in the generator 64. Heat supplied to
, ; .
the generator 64 evaporates a rerigerant which is carried by
a line 107 to the condenser 65.~ A5 the refrigerant is lique~ied~
.~ in the condenser 65, heat is l1berated. Heat may be absorbed
-i : ,~ .
- 1~35~703
by hygroscopic fluid circulated through the coil 83 to heat such
fluid as required for evaporating water vapor from the fluid in
the regenerator 63. Any remaining unwanted heat in the
condenser 65 may be absorbed by a heat trans~er ~luid circulated
through a heat exchange coil 108 in the cendenser 65. The
heated heat transfer fluid flows through a line 109 to a heat
exchange coil 110 in the evaporative cooler or cooling tower 97
and the cooled Eluid is returned through a pump 111 and a
line 112 to the coil 108.
The liquefied refrigerant in the condenser 65 passes :~
through a line 113 which includes an expansion valve 114 to
the evaporator 66. As refrigerant is vaporized in the . :
evaporator 66, heat is absorbed from heat transfer fluid
circulated through the coil 104 and through a heat exchange
coil 115. From the evaporator 66, the vaporized reErigerant ~
flows through the absorber and heat exchanger 67, wherein it is ~::
again liquefied and returned to the generator 64. The pump 111
also circulates heat transfer fluid through the line 112, a heat . ~ .
exchange coil 116 in the absorber and heat exchanger 67, the
line 109 and the heat exchange coil 110 in the evaporative ~ -
cooler 97 for removing waste heat from the absorber and heat
exchanger 67. : :~
:
On hot sunny days, heat transfer fluid may be :
circulated through the solar collector 60 at a rate to maintain
a temperature of about 200Fo in the solar energy storage ~ ~-
tank 61~ If refrigerant is heated to substantially~200F. in
: ::
. the generator 64 by heat transfer from the solar energy
.
Y storage tank 61, the absorption refrigeration apparatus~will
:. ~ .
cool the evaporator coil 104 to~about 55F. for coo1ing~the~ ;
glycol solution which dehumidifies air passed through the ~ - -
contactor 62 ~ At the same time, the dilute glycol solution in~ . :
the regenerator 63 is heated~to about 140F. by circulating~
~-12- :
~.
l~SS7(~3L
a portion of the solution through either the condenser coil 83
or the coil 88 in the solar energy storage tank 61. At these
operating temperatures, air leaving the contactor 62 can be
cooled to a dry bulb temperature of about 55F. and
dehumidified to a wet bulb temperature of about 30F.
The conditioned air delivered to an air conditioned
space can also be cooled. As previously indicated, the
blower 101 draws air through the contactor 62 wherein moisture
is removed from the air through contact with the hygroscopic
glycol solution. The dehumidified air then Elows through a
duct 117 to a space, room or building being conditioned. The
duct 117 passes through an indirect heat exchanger 118 wherein ;~
the dehumidified air may be sensibly cooled to a predetermined
temperature. The indirect heat exchanger 118 includes a heat
exchange coil 119 which is connected through lines 120 and 121
to a heat exchange coil 122 in the evaporative cooler 97. A
pump 123 may be operated to circulate a heat transfer fluid
between the coil 119 where heat is absorbed from the
dehumidified air and the coil 122 where the absorbed heat
energy is dissipated in air and water passed through the
cooler 97. The heat exchanger 118 also includes a heat --
exchange coil 124 through which a chilled heat transfer fluid
may be circulated. The coil 124 is connected through lines 125
and 126 to the heat exchange coil 115 in the evaporator 66 of
the absorption refrigeration apparatus. Heat transfer fluid
which is chilled in the evaporator 66 may be circulated through
the coil 124 for cooling air flowing through the duct 117. In
addition to the dehumidified fresh air, the duct 117 may be
connected to receive return air from a duct 127. The duct 127
passes through~a heat exchanger 128 wherein the return air may
be cooled, when necessary, prior to mixing with the~dehumidified
fresh air in the duct 117. The heat exchanger 128 includes a
- :
-13-
l~SS7~
heat exchange coil 129 which is connected through a three-way
valve 130 to the line 125 and is connected directly to the
line 126 for receiving chilled heat transfer fluid from the
coil 115 in the evaporator 66 of the absorption refrigeration
apparatus. The return air duct 127 may be connected to mix
the return air with the fresh air entering the contactor 62
instead of connecting it to mix the return air with the
dehumidified air in -the duct 117 (as shown). In this mode of ;
operation, the heat exchanger 128 may be by-passed or the valve
130 may be closed to prevent circulation of a cooled heat
exchange fluid through the coil 129 in the heat exchanger 12~.
After passing through the contactor 62, the dehumidified j` -``
mixture of return air and fresh air may be cooled sensibly in
the heat exchanger 118, if necessar~
The duct 117 carrying dehumidified air from the
contactor 62 also may be connected to pass through a humidifier ;-~
or washer 131. A pump 132 circulates water to a plurality of
: . -
nozzles 133 which spray a mist of water for humidifying the airdelivered to the air condltioned space, and simultaneously~
20 adiabatically cooling such air. Turning to Fig. 4, a~ - :
psychometric chart is shown for a mode of operation in which~ ~
.
the air delivered to an air conditioned space is adiabatically
cooled by means of the washer~131.~ Fig. 4 shows the~
conditioning of outside or fresh air having a dry bulb ; ~ ~ -
temperature of 102F. and a wet bulb temperature of 44F.,~ ~ -
point A. This air is mixed wit;h~half its weight of;return air ~ -
having a dry bulb temperature~of 81F. and a wet bulb
temperature of 56F., as shown at point B. The mixture results
in air having~a clry bulb temperature of about 95F. and~a wet
bulb temperature~of about 48~F., point C. This mlxture is~
delivered to the contactor 62 wherein it is dehumidified and
cooIed~to a dry bulb temperature~of 84F. and a~wet bulb~
14-
~ ~
10557~1
temperature of 35F., point D. The air is then adiabatically
cooled in the washer 131 to a dry bulb temperature of 63F. and
a wet bulb temperature of 5SF., as shown at poin-t E. At this
point, the air enters the building distribution svstem in a
condition identical to that discussed in reference to Fig. 2.
The air will be heated within the distribution system to a ~`
dry bulb temperature of 67~F. without changing the wet bulb
temperature of 55F., point F, and under these conditions is
delivered to the air conditioned space as required to maintain
a dry bulb temperature of 76F. within the space. It will be
noted that the apparatus shown in Fig. 3, operated as described,
cools the mixture of outside air and return air to a drv bulb
t:emperature of about 63F. This is done by dehumidiying to a
lower dew point than is required for humidity control, ollowed
by adiabatic washing, and can be accomplished at fairly high
contactor temperaturesr e.g., tempera-tures which can be `
achieved in the coil 96 (Fig. 3) of the evaporative cooler 97
provided that dry ambient air is available as indicated by
point A in Fig. 4. However, if available ambient air is
relatively humid, for example as illustrated by the point A in
Fig. 2, the hygroscopic glycol solution must be circulated
through the coil 104 of the evaporator 66 to accomplish this
result. The evaporator 66, however, need not provide a
particularly low temperature, 70F. being entirely adequate, and
a temperature that can be readily achieved when the condenser 65
is at 140F., or at a temperature sufficiently high to enable
regeneration of the glycol solution.
Referring, now, to Fig. 5, air conditioning apparatus
according to the invention, in another embodiment, comprises a
solar collector 135, chemical dehumidification apparatus
including a contactor 136 and a regenerator 137 and
refrigeration apparatus includ1ng a compressoF 138, a
:. .
.
;~ :
iL~55~
condenser 139 and an evaporator 140. The compressor 138 of the
refrigeration apparatus is driven by an expander 141, which is
a part of a rankine cycle engine. A refrigerant such as F-113,
is heated, as subsequently describ~ed in more detail, by energy
from the solar collector 135 and flows through a line 142 to -
the expander 141 where its expansion drives a turbine (not
illustrated) which is operatively connected through a shaft 143
in driving relationship with the compressor 138. Refrigerant
flows from the expander 141 through a line 144, a regenerator
145, a line 146, the condenser 139 and a line 147 to a ~ ~:
pump 148. Refrigerant flows from the pump 148 through a ~:
line 149 back to the opposite side of the regenerator 145 and : :: -
from thence through a line 150 to a storage tank 151 for water .
heated in the solar collector 135 or using augmenting heat, as
subsequently explained. Refrigerant flow can be controlled so .-
that the temperature entering tha expander 141 is about 200F.,
while the temperature entering the condenser 139 is about 140F.
Refrigerant is circulated from the condenser 138 through a
line 152 to the condenser 139, and, thence, through a line 153 .
to the evaporator 140, where it can be flashed to a temperature
of about 70F. before being returned to the compressor 138.
A hygroscopic solution of a glycol is circulated by
a pump 154 through a line 155 from the contactor 136, and is
. .
delivered to a three-way valve 156 which divides the flow :
between a line 157 and a line 158:. The glycol solution flowing
in the line 157 lS delivered to the evaporator 140 and from ~ .
there flows through lines 159 and 160 into the contactor 136
to be sprayed~from nozzles:l61. Glycol solution delivered to
the line 158~flow5 directly.to;the line 160 and to the
no2zles 161. The three-way valve 156 is controlled to maintain
a predetermined temperature of the hygroscopic glycol solution~
sprayed from the:nozz1es 161.
,
-16- .... .
~L~S570~
Heat is transferred from the condenser 139 to a
hygroscopic glycol solution which i5 circulated from the
regenerator 137 by a pump 162 through a line 163, and to a
three-way valve 164 which divides the flow between a line 165
and a line 166. The hygroscopic glycol solution delivered to
the line 165 is circulated to the condenser 139 where it is
heated by heat transferred thereto from refrigerant from the
compressor 138 and from refrigerant circulated in the solar
energy collection system, and is then returned through a
10line 167 into the regenerator 137, where it is sprayed from
nozzles 168. The three-way valve 164 is controlled to divide
the flow of hygroscopic glycol solution through the
condenser 139, as just described, and through the line 166 to
maintain a predetermined temperature of the solution as it is
sprayed within the regenerator 137.
~ir, preferably relief air from the building served :~
by the apparat~s, enters the regenerator 137, as indicated by
an arrow 169, passes through an indirect air-to-air heat
exchanger 170, and from thence through an indirect air-to-
liquid heat exchanger 171 and then downwardly with hygroscopic
glycol solution being sprayed from the nozzles 168, laterally ::
to the left and then upwardly through the opposite side of
the air-to-air heat exchanger 170 and a blower 172 by which lt
is discharged from the regenerator~137, through an indirect
heat exchang~r 173 and then is exhausted through a duct 174.
Heat is transferred to the air entering the regenerator 137
: ~ (a) from air traveling upwardly through the regenerator:~137 to
~the blower 172~in the indirect heat exchanger I70 and (b) from
:~~ hygroscopic glycol solutlon clr~culated as subsequen:tly
~ 30 described in more detail through the indirect heat ~ ~ -
. .
exchanger 171. Heat is also transferred from the e~fluent
~rom the blower 172 in the lndirect heat exchanger 173 as
: : .. .
, -17~
l~S5~
subsequently described in more detail. The apparatus can be
operated so that air from inside the regenerator 137 entering
the indirect heat exchanger 170 is saturated with water vapor
and at a dry bulb temperature of 120F. sy indirect heat
exchange with the building exhaust air, which can enter the
indirect heat exchanger 170 at a dry bulb temperature of
about 83F. and a dew point of about 56F., the exhaust air
entering the blower 172 can be at a dry bulb temperature of
96F., and have a dew point of 79F. while, as a consequence
of heat transfer in the indirect heat exchanger 173, the
exhausted air in the duct 174 can be saturated with water vapor
and at a dry bulb temperature of about 75F.
Air is drawn into the contactor 136 by a blower 175,
and flows downwardly therethrough in contact with cooled
hygroscopic glycol solution from the nozzles 161, then laterally
to the left and upwardly through the blower 175, a line 176,
an adiabatic washer indicated generally at 177 and a duct 178
to a space ~not illustrated) to be alr conditioned.
The apparatus of Fig. 5 also includes an evaporative
cooler 188 from which cool water can be circulated by a
pump 189 through a line 190 to an auxiliary coil (not ~ -`
illustrated) in the condenser 139. Water is returned from the
condenser 139 through a line 191. Water from the cooler 188
is used to maintain a thermal ba}ance whenever there~is excess
heat in the condenser 139 above that required by the
regenerator 137.
The apparatus of Fig. 5 is designed to condition air
; - :
when the outside dew point is comparatively high, e.g., a dry
bulb temperature of 92F. and a wet bulb temperature of 76F.:
point A, Fig. 2, and to condition that air or, preferably, a
mixture of that air with return room air to a }ower wet bulb
temperature than is required or humidity control in the
`; ~ ''' ':
-18-
105~7~
space, e.g., a dry bulb temperature of 84F. and a wet bulb
temperature of 35~F.: point B, Fig. 4. This air can then be
adiabatically washed in the washer 177, distributed throughout
the building, and used as required to maintain temperature
and humidity.
As has been stated above, a refrigerant that has
been heated by energy from the solar collector 135 (Fig. 5)
flows through a line 142 to the expander 141. Refrigerant in
the line 142 has been heated as it flowed through a liquid-to-
liquid indirect heat exchanger 192 in the heated water storagetank 151. When solar energy is available, that eneryy is
intercepted by the solar collector 135 and transferred to ``
water circulated from the storage tank 151 through a line 193
by a pump 194. Heated water retuxns to the storage tank 151
from the solar collector 135 through a line 195. The apparatus
also includes an indirect liquid-to-liquid heat exchanger 196
within the storage tank 151. Whenever required heat from the
solar collector 135 can be supplemented, or replaced, by heat
from an auxiliary steam source 197 connected to the indire~t
heat exchanger 196.
Referring to Fig. 6, a heating, ventilating and air
conditioning system is shown in which thermal energy from a
solar collector 200 is augmented with waste heat from a diesel
engine 201 for regenerating a desiccant such as a glycol
solution in a regenerator 202. Outside air passes from an air - -~
-:
intake 203 through a chemical dehumidifier 204 which may, for ~ -
example, be the same as the contactor 12 shown in Fig. 1.
Within the dehumidifier 204, moisture is removed from the -
~; fresh outside air. At the same time, heat of sorption is --
transferred through a coil 205 to a cooling tower 206 and thence
transferred to the atmosphere. From the dehumid1fier 204,~the
dehumi`dified air passes through a duct 207 along with return
::
'
-19-
" 1ai 557~ ~
air from a duct 208 to a cooling coil 209. ~leat transfer fluid
is circulated from the cooling coil 209 to refrigeration
apparatus 210. The refrigeration apparatus 210 transfers heat
from the cooling coil 209 to a cooling tower 211 in a
conventional manner. The refrigeration apparatus 210 is driven
by the diesel engine 2Ql. The diesel engine 201 may also be
connected to drive an electric generator 212 and an emer~ency ' '
power generator 213, when desired.
The dehumidified and chilled air discharged from th~
cooling coil 209 passes through a blower 214 ancl a duct 215
and is then discharged through defusers 216 located in the
ceiling of an air conditioned space 217. Building exhaust air
and return air from the space 217 is drawn through a lighting
fixture 218 into a duct 21~ by return air fan 220. As the
return air passes through the lighting fixture 218, waste
thermal energy is removed from such lighting fixture 219. As '
; much as S0 percent or more of the lighting fixture thermal
load may be removed from the space 217 by exhausting the
return air through the lighting fixture 218. This in turn
.
decreases the quantity of air needed to be supplied to the
space 217 to maintain a desired space temperature. '
The return air withdrawn from the space 217 thr~ough ~ "' ' '
the lighting fixtures 218 will be at an appreciably highe~r
,.
temperature than the normal temperature of the conditioned
space 217. For example, if the,,space 217 is maintained at
,
75F.,~ the return air may be on the order of 87F. A portlon -~
of the return~air is exhausted ~from the building through the
` regenerator 202. The duct~208~is connected to a duct 221 in
,~ which a portlon of the return air ls mixed with outside air,
as needed,~ from~a duct 222. ~A~blower 223 forces air from the~
,~ duct 221 through the regenerator~202 and~exhausts the moisture ~ ~
~ - laden air through~a building exhaust duct 224. A pump 225 is " ''
~55701
connected to circulate a dilute glycol solution from the
contactor 204 to the regenerator 202 and to return concentrated
gylcol solution from the regenerator 202 to the contactor 204.
The glycol solution within the regenera-tor 202 is heated by
a coil 226 through which a hot heat transfer solution is
circulated. The heat transfer solution is circulated to
receive solar energy from the sola:r collector 200 and also to
receive thermal energy from a coil 227 located in the exhaust
stach for the diesel engine 201. Through the use of solar energy
from the solar collector 200 and exhaust energy from the
coil 227 in the diesel engine exhaust stack, sufficient heat is
available for maintaining the desiccant within the
regenerator 202 at 200F.
Referring now to Fig. 7, still a further modified
embodiment is shown of apparatus for conditioning air within
a space 250. The apparatus generally uses two stages of
dehumidification, refrigeration apparatus driven from a diesel
engine and an evaporative cooler for cooling air supplied ~ -
through a ceiling diffuser 251 to the space 250. A combinatlon
of solar energy and waste heat from the diesel engine which
drives the refrigeration apparatus is used for regenerating
desiccant for the two stages of dehumidification.
A blower 252 is connected to withdraw air from the
space 250 through lighting fixtures 253 located within a
ceiling 254 for the conditioned space 250. As air is withdrawn
through the lighting fixtures 253, a portion of the heat
produced by the lighting fixtures 253 is withdrawn from the
space 250, thereby reducing the quantity of air needed to be;
supplied through the diffuser~251 to cool the space 250 to a~
desired~temperature. A portion of the air withdrawn from the
space 250 by the blower 252~ is eirculated through a duct 255
to a mixing valve or chamber 256. Fresh air which is~to be~
-- 105~70~L
added to the conditioned space 250 er-ters the apparatus through
a duct 257. Fresh air entering -through the duct 257 passes
through a contactor or chemical dehumidifier 258 wherein it
contacts a spray of a liquid chemical desiccant, such as a
glycol solution. As such fresh air is d~humidified through
contact with the desiccant, heat oE~sorption is generated. A
heat transfer fluid circulated between a coil or indirect heat
exchanger 259 and a cooling tower 260 removes the heat Gf
sorption from the dehumidified fresh air. The dehumidified ~ -
fresh air leaves the dehumidifier 258 through a duct 261 which
connects with the mixing valve or chamber 256 wherein it mixes
with recirculated air from the space 250. From the mixing ;
valve 256, the fresh air/recirculated air mixture passes through
a dehumidifier 262. The dehumidifier 262 is in the form of a
rotating wheel having a crystalline desiccant, such as silica ~`
gel, located within a porous honeycomb structure. As the
dehumidifier 262 is rotated about an axis 263, the air mixture
passing through the dehumidifier 262 is exposed to regenerated
desiccant crystals for removing moisture from such air mixture. `
From the dehumidifier 262, the air passes into a duct 264 `
which is connected through a first indlrect heat exchanger
coil 265 and a second indirect exchange coil 266 to a fan or
blower 267. The first indirect heat exchange coil 265 is
connected to a cooling tower 268 for removing heat of sorption
fro~ the dehumidified air mixture leaving the dehumidifier 262
and dissipating such heat of sorption to the atmosphere.~ The
second indirect heat exchange co~il 266 is cooled by
- refrigeration apparatus 269. A diesel engine 270 drives the
: : ~
~ refrigeration apparatus 269 for transferring heat from the `
,
second coil 266 to a cooling tower 271. The blower 267~
circulates the cooIed air from the second coil 266 through an
evaporative cooler 272 to the~diffuser 251 located within the
. . .
; '
-22-
1~5~01
ceiling structure 254 over the conditioned space 250. Within
the evaporative cooler 272, molsture is evaporated into the
air to decrease the temperature of such air. Throu~h the use
of the dehumidifiers 258 and 262~ the moisture content or wet
bulb temperature of the air entering the evaporative cooler 272
is low. Therefore, considerable cooliny is achieved through
water evaporation. Air supplied from the evaporative
cooler 272 to the space 250 may, for example, have a temperature
on the order of 40F. This low temperature is achieved through
the use of a minimum load on the refrigeration apparatus 269.
The liquid desiccant which dehumidi~ies fresh air
within the dehumidifier 258 is regenerated through the use of
solar energy. A pump 273 circulates dilute desiccant from the
dehumidifier 258 to a regenerator 274 and returns a concentrated
desiccant from the regenerator 274 hack to the dehumidi~ier 258.
A pump 275 circulates a heat transfer fluid between a coil 276
within the regenerator 274 and a solar energy collector 277.
The heat transfer fluid is heated to a predetermined high
temperature, such as approximately 200F., within the solar
collector 277. The heated heat transfer fluid is then
circulated from the sola~ collector 277 to the coil 276 where
such heat is transferred to the dilute hygroscopic solution
during regeneration. After the dilute solution is heated, it
is contacted with air which picks up moisture from the dilute
solution and then the hot moist air is discharged through a
duct 278 to the atmosphere. To increase the efficiency of ~ -
the system~ at least a portion of the air supplied to the ~ ~
.:
~- regenerator 274 is in the ~orm of exhaust air from the
conditioned space 250. The return air duct 255 is connected
through a hlower 279 to supply building exhaust air to the
:: . .
regenerator 274. Fresh outside air, as needed, is also
~ supplied from a duct 280 through the blower 279 through the
.
~ -23-
ii55~
regenerator ~74. Since the relative humidity of air wi-thin the
conditioned space 250 is relatively low, the efficiency of
moisture transfer from the dilute hygroscopic solution to the
air discharged through the regenexator 274 is increased over
systems using only outside for regenerating a desiccant. The
diesel engine 270 is connected to drive the refrigeration
apparatus 269 and also to drive auxiliary electric
generator 281. The output from the electric generator 281
may be used, for example, for driving the various pumps,
blowers and fans within the system for conditioning air within
the building space 250. In addition, it may be used for any
other desired purpose. If the environmental control system
shown in Fig. 7 is used for conditioning air within a
hospital, the diesel engine may also be connected through a
clutch 282 for driving an emergency electric generator 283
during a failure of the commercial power source used for
operating lighting and equipment in such hospital. Waste heat
is a by-product from operation of the diesel engine 270. A
pump 284 circulates a heat transfer fluid, such as water,
through passages around cylinders within the internal
combustion engine 270 for cooling such cylinders The
pump 284 circulates such water from the engine 270 to an
indirect fluid-to-air heat exchange coil 285. Exhaust gases -
also carry waste heat from the engine 270. The exhaust gases
pass through an indirect air-to-air heat exchanger 286 for
recovering waste heat from such exhaust gases.
~ he granular desiccant within the dehumidlfier 262
is regenerated with exhaust air~from the building space 250
along with the regeneration of liquid desiccant within the
regenerator 274. A portion o~ the air withdrawn from the
space 250 by the~blower 252 flows~from the blower 252 into
a duct 287. The duct 287 is connected sequentially through
-, ~ :
:
.
-24- -
.
1(~557~L
the heat exchanger 2~5 and the heat exchanger 286. The hot
water circulated thxough the hea-t exchanger 285 may, for
example, heat the air in the duct 287 to approximately 200F.
The hot exhaust gases passing through the heat exchanger 286
further heats this air to approximately 300F. The 300~F. air
leaving the heat exchanger 286 in -the duct 287 is circula-ted
through the dehumidifier 262 to regenerate the desiccant
therein. The hot air within the duct 287 is circulated
through a portion of the desiccant within the dehumidiier 262
as the wheel containing the desiccant rotates. The portion of
the hot air circulated through the desiccant for regeneration
is spaced from the portion of the regenerated desiccant
contacted by air circulated through the duct 264 for delivery
to the conditioned space 250. A blower or fan 288 withdraws
the moisture-laden hot air from the dehumidifier 262 and
discharges such air through a duct 289 to the atmosphere
outside the building containing the conditioned space 250.
The systems of Figs. 6 and 7 represent considerable
increase in energy efficiency over a conventional system in
which chilled fresh air is mixed with recirculated air for
conditioning spaces within a building. The efficiencies are
also increased over prior art solar systems because there is
not a total reliance on the availability of solar energy.
Furthermore, both the waste heat from the diesel engine and
solar energy are available for winter heating.
In the embodiment shown in both Fiys. 6 and 7, a
diesel en~ine was operated to drive r~frigeration apparatus
and to drive generators which serve as a source of electricity
for powering the system. The diesel engine also p~oduces
waste heat which is used for regeneration of a desiccant
within a chemical dehumidifier. In still another embodiment
of the invention, the diesel englne can be replaced with a
:~ '
-25- ~
~1~3557~
bank of fuel-cells. A fuel-cell directly converts a Euel and
an oxidant into an electric current: and, as a by-product,
also produces heat. The heat level depends upon the
construction of the fuel-cell and various other factors such
as the nature of the fuel and the oxidant used within the
fuel-cell. Various fuel-cells operate anywhere from
relatively low temperatures, below 200C., up to very high
temperatures, above 900C. A bank of fuel-cells may be used
to replace the diesel engine and the electric generators
within the systems of either Fig. 6 or Fig. 7. The fuel-cell
generates electricity which operates the various fans, blowers
and pumps within the system and, when necessary, also drives
electrically powered refrigeration apparatus. Waste heat
from the fuel-cell is transferred to air circulated through
a desiccant regenerator or through a granular or solid
desiccant for removing moisture fxom such desiccant. The hot,
moisture-laden air is then discharged to the atmosphere.
Although only preferred embodiments of the invention
have been described above, it will be appreciated that various
changes and modifications can be made without departing from
the spirit and the scope of the following claims. ~t should
also be appreciated that the above-described apparatus may be
operated in different modes to meet seasonally changing
requirements. For example, during winter operation, the
dehumidifier can be reversed for humidifying fresh air supplied
to a space. A heated dilute hygroscopic glycol solution, or
even water, can he sprayed in the contactor 12 (Fig. 1) for
humidifying air circulated through the contactor. When solar
energy is available, the solar energy collector is used for
heating such solution. The temperature of the solution and
the rate at which it is sprayed from the contactor nozzles is
controlled to give a desired wet bulb temperature at the outlet
.: ~
.., :
-26-
.
~5~70~
from the contactor. The humidified air can then be heated, as
necessary, to maintain a desired temperature in the space
being air conditioned. Also, at least one air-to-liquid heat
exchanger analogous to the exchanger 171, to the exchanger 173,
or to both (Fig. 5) can be used in a similar manner in the
apparatus of Fig. 1 or in the appa:ratus of Fig. 3.
-:
,~
: ~ ~ ''. '
~ :' -
~,. ....
-27-
.
