Note: Descriptions are shown in the official language in which they were submitted.
tl~81~,J
' This invention relates to a method of, and system for, storing
heat. Primarily, it is directed to the storage of heat produced by off-
peak electrical power. It is adaptable, however, to store heat produced
by other means.
Various methods and systems have been proposed for the storage
of heat and consequently heat storage of itself is not new. It has been
suggested that gravel, rocks, concrete, soapstone, and even blocks of
steel and the like be heated to a high temperature and that the heat con-
; tent of the material be thereafter used while the temperature of the heat
absorbing means goes down. Such devices of the prior art, however, are
limited in their applicability by the fact that the only heat stored is
; sensible heat, which is a function of the specific heat of the material
used. Since the specific heat of available materials is low, usually in
the neighbourhood of 0.2 B.T.U. per pound, the heat storage capacity of
such material between, for example 200 and 500F., is only 60 B.T.U. per
pound. This renders such heat storing means impractical for space heating
purposes because of the large bulk necessary to provide storage for large
amounts of heat and because of the need to minimize heat loss from the
heat storage means by insulation.
More practical heat storage systems have been devised in which
heat of solution or heat of fusion, or a combination of both, are utilized.
In such system, a crystalline material having a large amount of water of
crystallization may be used, the material being so applied and selected
that, upon being heated, the solid material melts or dissolves in its own
water of crystallization, with the resulting storage of relatively large
quantities of heat in the form of latent heat of fusion and solution. The
heat so stored can be recovered by permitting the material to recrystallize.
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11583L21
. United States Patent No. 2,450,983 issued
October 12, 1948 to C.M. Osterheld provided an off-peak
heat storage system using electric
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1158121
heaters which resided in the use of an automatic thermostatic control
system to energize the electrlc~heater in conjunction with an additional
input as to whether it was night or day. An electric heater was provided
for heating a heat storage mass. A light~sensitive cell was provided
wh;ch was subject to daylight and to darkness. A plurality of thermostats
were provided in a close heat-receiving relation to the heat storage mass
and were adapted to move to closed position at different temperature values
of the heat storage. A plurality of time delay relays were provided which
were electrically connected in series electric circuit with certain of the
thermostats, each relay being a normally open thermally-actuable member
and a heating coil therefor. A switch which was controlled by the light-
sensitive cell was provided for energizing the heating cells of time-delay
relays after fall of darkness to cause closure of the thermally-actuable
member after a predetermined period of time, and energization of such
heater.
United States Patent No. 2,677,243 issued May 4,
1954 to M. Tel~es purportea to proviae an apparatus for
storing heat, utilizing the principle of the heat of fusion,
and a process for releasing the heat thus stored. Accor~
ding to that patentee, a limited portion of the heat storage composition
was either maintained at, or was occasionally subjected to, a temperature
substantially lower than the melting point of the composition, and speci-
fically below the temperature of metastable supersaturation of the composi-
tion. By this means seeding nuclei were maintained or formed in a limited
portion of the mass of heat storage material, and when the same had been
undercooled below its melting point in an effort to extract heat therefrom,
crystal formation based upon such nuclei spread rapidly throughout the
mass, thus allegedly releasing large quantities of latent heat.
United States Patent No. 2,856,506 issued October 14, 1958 to
M. Telkes purported to provide a method of storing and releasing heat
1~8121
utilizing a heat storage material and a method of heating a substance which
included transferring stored heat thereto from such a material. The
patentee provided a system, including apparatus and method~ for storing
heat at a relatively high temperature by utilizing as the heat storage
medium, a crystalline solid which is dimorphic, that is to say, which
changes from one crystalline form to another on the application of heat,
which has a transition temperature between 300 and 550F., and which has a
relatively high heat of transition. The material suggested was anhydrous
sodium sulfate, either by itself or modified by the addition of other
salts, which could be converted by heating from the rhombic crystal form
to a hexagonal form.
United States Patent No. 3,382,917 issued May L4, 1968 to R.E.
Rice provided a heat storing system including a unit in which heat may be
stored at widely-varying temperatures, a heat exchanger, a chamber for
hea~ing fluid or other heater, a conduit leading from the storage unit
to the exchanger through which fluid may be circulated to transfer heat
from the unit to the exchanger, a second conduit leading from the exchanger
to the heater for transferring heat from the exchanger to the heat, regu-
lating means in the first conduit for varying the rate of heat transfer
from the un:Lt to the exchanger, and thermostatic means in the second con-
duit for controlling the regulating means. The regulating means suggestedwas a circulator and flow modifier. The fluid may be either gas or liquid,
the circulator may comprise a blowerJ pump or fan, and the flow modifier
may comprise a by-pass or throttle.
United States Patent No. 3,989,927 issued November 2, 1976 to
GØ Erb provided a storage heater for heating a gaseous heat extraction
medium which is formed of a container of heat resistant material, prefer-
ably metal. At least one guide duct, in the Eorm of a tube for carrying
the gaseous heat extraction medium, extended through the container which
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1~58~2~
held a heat storage medium in the form of a pourable bulk of particulate
solid material. The thermal storage medium comprised a bulk in which the
product of specific heat of the solid material and the bulk density of the
mass was a specified amount.
In spite of these patents, there is still a need for a system
having a high heat storage capacity, one in which there is substantially no
heat loss from the system when heating is not required, one which does not
require addsd exchangers in direct connection to the heat storage unit,
and one which requires a fairly low charging temperature.
One system for the utilization of solar energy for
cooling is described in an article by D.I. Tchernev entitled
"Solar Energy Application of Natural Zeolites". The author
describes a system using natural chabozite on clinoptilolite
as the solid absorber and water vapour as the working fluid
in a zeolite system to provide domestic hot water and space
heating. One such system combines a condensor and an evapo-
rator into a single unit that is cooled by an external water
loop. During the day, water vapour desorbed from the solar-
heated zeolite is condensed in this unit and the liquid water
is stored in the condenser in a condensate storage tank until
evening. The heat of condensation may be used for providing
domest`ic hot water and for space heating. Whenever there is
a demand for heat, hot water can be circulated through a coil
located in air ducts of a corced air system, and the heated
air is distributed throughout the building.
There have been two basic problems with the use of
dessicants for storage systems even in the system described
above. One is the disposal of the hot moist air produced
*
U.S. N.T.I.S. pp Rep, 1977 pp 266055, GRI 1977 77(14)156.
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``~ 1158121
during the drying out or charging cycle; the other is the
requirement for moist air during the wetting or heating
cycle.
Thus, an object of one broad aspect of this invention
is the provision of an improved dessicant heat storage system
An object of another aspect of this invention is the
provision of an improved method for dessicant heat storage.
Applicant has provided an improved such system in
which the problems described above are minimized.
The present invention provides an improvement in a system based
on gas adsorption for chemical potential storage of energ~ (CES). Such `
gas adsorption concept can provide the means for constructing a "CES"
system or "heat battery"/ The present invention uses a dessicant, e.g.,
zeolite, and a means of drying out or charging the system by the use e.g.,
of off-peak electric power. The heat is then released as required during
periods of peak electric power by the re-introduction of moisture, in
effect releasing the stored heat of vaporization.
Thus, by one broad aspect of this invention, a des-
sicant heat storage system is provided comprising (a) a source
of air; (b) a fan means for circulating the air in a circu-
lation system including an outgoing loop and return loop for
the circulating air; (c) selectively operable evaporator heat
exchanger means
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1158121
disposed in the outgoing loop of the circulating air; (d) selectively operable
air wetting means disposed in the outgoing loop of the circulating air;
(e) selectively operable air heating means disposed in the outgoing loop of
the circulating air; (f) a dessicant material-containing enclosure used to
provide heat storage disposed in the circulation system, the enclosure
consisting essentially of (i) a rectangular box; (ii) a bottom intake plenum;
(iii) an upper outflow plenum; (iv) a plurality of hollow tubes, each
comprising an outer mesh shell, an inner mesh shell , a free inner core and
dessicant material filling the annular cylinder between the inner shell and
the outer shell; (v) a tubular inlet collar projecting into the core of each ~
hollow tube, for feeding air from the bottom intake plenum to the hollow tubes;
(vi) a tubular outlet tubular collar projecting into the core of each hollow
tube for feeding air from the hollow tubes to the upper outflow plenum;
(vii) means for feeding air to the bottom intake plenum; (viii) means for
withdrawing air from the upper outflow plenum; (ix) air inlet means to the
bottom intake plenum from the outgoing loop of the circulating air; and
(x) air outlet means from the upper outflow plenum to the return loop of the
circulating air; whereby air entering the bottom intake plenum passes to the
upper outflow plenum by a primary flow path directly through the free inner
core of the hollow tube into which it is directly fed by an associated tubular
inlet collar and by a secondary permeating flow path through at least one
annular cylindrical, dessicant-filled tube to a free core into which it had
not been directly fed by an associated tubular collar; (g) selectively
operable condenser heat exchanger means disposed in the return loop of the
circulating air; and (h) selectively operable air control means disposed in
the return loop of the circulating air, for selectively; (i) circulating the _.
air through a primary heat distribution system; or (ii) recirculating the air
through the circolating system.
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By another aspect of this invention, a dessicant heat storage system
is provided in the form of a furnace adapted to store heat, comprising (a) an
air inlet; (b) an air outlet; (c) an airflow channel, connecting the air inlet
to the air outlet; (d) a dessicant-containing enclosure used to provide heat
storage and including a bed of adsorbent energy storage dessicant material
in the airflow channel, all airflow in the channel being directed through
the bed, the dessicant-containing enclosure consisting esse~tially of (i) a
~ ~ rectangular box; (ii) a bottom intake plenum; (iii) an upper outflow plenum;
(iv) a plurality of hollow tubes, each comprising an outer mesh shell, an
inner mesh shell, a free inner core and dessicant material filling the annular
cylinder between the inner shell and the outer shell; (v) a tubular inlet
collar projecting into the core of each hollow tube, for feeding air from
the bottom intake plenum to the hollow tubes; (vi) a tubular outlet tubular
collar projecting into the core of each hollow tube for feeding air from the
hollow tubes to the upper outflow plenum; (vii) means for feeding air to the
bottom intake plenum; (viii) means for withdrawing air from the upper outflow
plenum; (ix) air inlet means to the bottom intake plenum from the outgoing
loop of the circulating air; and (x) air outlet means from the upper outflow
plenum to the return loop of the circulating air; whereby air entering the
bottom intake plenum passes to the-upper outflow plenum by a primary flow
path directly through the free inner core of the hollow tube into which it
is directly fed by an associated tubular inlet collar and by a secondary
permeating flow path through the at least one annular, cylindrical, dessicant-
filled tube to a free core into which it had not been directly fed by an
associated tubular collar; (e) air heating means, positioned upstream of the
bed of adsorbent energy storage material; (f) air dehumidifying means, ^`
positioned downstream of the bed of adsorbent energy storage material; and :
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tl5812~
(g) means to control the quantity of airflow through the airflow channel;
whereby air from a buiiding containing the furnace is humidified by the air
humidifying means and/or by the ambient release of moisture in the building
and is blown through the absorbent energy storage dessicant material, the
material absorbing the moisture in the air thereby to dehumidify that air
and releasing stored in the form of heat with the absorption of the moisture.
By a variant of these aspects, the absorbent, energy storage,
dessicant material is a zeolite.
By another variant of these aspects, the invention is in the form
of a forced air furnace. ~ -
By a variation thereof, the system is a retrofit system in com-
bination with the forced air furnace.
By another variant, the primary heat distribution system com-
prises a hot air/hot water heat exchanger.
By another variant, the primary heat distribution system com-
prises a high velocity air duct.
By a still further variant, the fan means is capable of pumping
300 - lO0 CFM.
By another variant, the means (c) comprises the evaporator stage
of a heat exchanger, where the air is passed in heat exchange relationship
with warm ist air, thereby to heat that air while cooling the warm moist
air.
By yet another variant, the means (c) comprises a heat pump,~
where that air is passed in heat exchange relation through the evaporator
stage of a heat pump, thereby to heat the air while cooling the warm moist
- air.
_ By still another variant~, the means (d) comprises a humidifier,
e.g. a drum-type humidifier or a spray-type humidifier.
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- By a further variant, the air heating means comprises an electric
resistance heater, e.g. of 10-30 KW.
By another variant, the air heating means comprises a heat pump.
By still another variant, the air heating means comprises a
solar collector.
By a still further variant, the air heating means comprises a
solar/electric heater.
By still another variant, the dessicant bed is constructed and
.
configured to absorb 5-20% of its own weight of water by the passage of
moist air therethrough.
By yet another variant, the means (g) comprises the condenser
stage of a heat exchanger, where moist warm air is passed in heat exchange
relation with cool air, thereby condensing out excess moisture from the air
and simultaneously recovering heat of evaporation from the air by trans-
ferring heat to the cool air.
By still a further variant, the means (g) comprises the condenser
stage of a heat exchanger, where moist warm air is passed in heat exchange
relation with cool air, thereby condensing out excess moisture from the air
and simultaneously recovering heat of evaporation from the air by transferring
heat to the cool air; and including means associated with the condensor stage
for recovering the moisture removed from the moist air; and including means
for using recovered moisture in the air wetting means.
By still another variant, the means (g) comprises the condenser
stage of a heat pump, where moist warm air is passed therethrough in heat
exchange relation with cool air, thereby condensing out excess moisture
from the air and simultaneously recovering heat of evaporation from the
air by transferring heat to the cool air.
By yet a further variant, the means (g) comprises thecondenser
- stage of a heat pump, where moist warm air is passed therethrough in heat
exchange relation with cool air thereby condensing out excess moisture from
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1158121
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- the air and simultaneously recovering heat of evaporation from the air by
transferring heat to the cool air; including means associated with the
condensor stage for recovering the moisture removed from the moist air; and
including means for using recovered moisture in the air wetting means.
By a variation thereof, the system includes means associated
with the condenser stage for recovering the moisture removed from the
moist air.
By a further variation, the system includes means associated
with the condenser stage for recovering the moisture removed from the
moist air~ and includes means for using recovered moisture in the air
wetting meanS.
By still another variant, the system includes thermostat and
associated control means for shutting off the air wetting means just
prior to the sensing of the temperature reaching a predetermined value.
By yet another variant, the means (h) includes air mixer means
selectively actuatable for: (xii) recirculating air through the dessicant
heat storage system; and/or (xiii) passing air to the primary heat dis-
tribution system.
By still a further variant, the means (h) includes air mixer
means selectively actuatable for: (i) circulating room air through the
dessicant heat storage system; and/or (ii) passing air to the primary
heat distribution system.
By another aspect of this invention, a method is provided for
dessicant heat storage comprising; (A) storing heat by the steps comprising:
(a) drawing outside air and/or inside air into an internal air circulation
system; (b) heating the outside air and/or passing heated inside air at a
temperature of 120-200 C. through a bed of dessicant material by passing the
~ air in a primary direct flow through a direct, unencumbered flow avoiding
contact with the major porti~n of the dessicant material, and through a
secondary permeating flow through the dessicant material, thereby drying the
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" 11S812~
dessicant bed, while storing heat in the dessicant bed and transferring
moisture to the air; (c~ withdrawing warm moist air at a temperature of up to
200 C. from the dessicant bed; (d) passing the warm moist air through a
condensation zone, whereby its moisture content is reduced; and (e) circulating
the drier air within the internal air circulation system; and (B) recovering
the stored heat by the steps comprising: (f) drawing internal air into the
air circulation system; (g) converting the air to moist air; (h) passing the
moist air through the dried dessicant bed, thereby wetting the bed to a moisture
content of 5-20% by weight while releasing heat from the bed to t~e air, and
drying the air; and (i) circulating the warm dry air within the internal
circulation system.
By a ~urther aspect of this invention, a method is Drovided for
storing and retrieving heat from an airflow comprising the steps of: heating
the airflow by means of an external energy source; directing the heated air-
flow through a bed of absorbent energy storage dessicant material by passing
the air in a primary direct flow through a direct, unencumbered flow avoiding
contact with the major portion of the dessicant material, and through a
secondary permeating flow through the dessicant material, to remove moisture
from the bed and to absorb heat therein; dehumidifying the airflow;
disconnecting the external energy source; humidifying the airflow; and
directing the humidified airflow through the bed of absorbent energy storage
dessicant material by passing the air in a primary direct flow through a direct,
unencumbered flow avoiding contact with the major portion of the dessicant
material, and through a secondary permeating flow through the dessicant
materialS to add moisture to the bed and to receive heat therefrom.
By a variant of these two method apsects, the absorbent, energy
storage dessicant material is a zeolite.
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12~
Thus, one embodiment of this invention for utilizing latent heat
during the drying cycle is to warm cold outside air which would normally
infiltrate a building, Cool air is pulled into the dessicant circuit
through a heat exchanger which cools the air leaving the dessicant bed
and removes moisture Erom the moist air. This, in turn, warms the cool
air, which then may be distributed through the system. The effect is to
pressurize the building to the extent that, for every cubic foot of air
introduced through the dessicant system, an equal amount is prevented from
entering through the building skin. The moisture removed bv this method
(possibly 40 or 50 gallons) is retained for use during the wetting cycle
of the heating cycle. During the wetting cycle, a cold water method of
humidification would be used as the vaporization of the liquid during peak
periods would require power equal to that used during the charging cycle
and negate the cost effectiveness of the system. A standard commercial drum
or spray type of humidifier would be used for the heating cycle.
.
A second embodiment of this invention is a system identical to
the first with a modification in the drying cycle to allow the use of a
heat pump to remove the moisture from the warm moist air and to re-intro-
duce the heat generated by condensation to the supply side of the dessi-
cant bed.
Which embodiment to be used would depend upon climate, type of
residence, local regulations andcustomer acceptance. For example, some
western Canadian provinces require minimum ventilating air be supplied to
the residence at all times. This would make the first embodiment
suitable.
The advantages over a conventional system are:
1. High heat storage capacity, in the neighbourhood of 250 B T ~ .
per pound of material.
2. Since only approximately 20% of the heat stored is sensible
11S~121
heat produced during the charging cycle there is no heat loss from the
system when heating i5 not required. The importance of this advantage is
significant particularly during the time of the year when maximum heating
is not required, e.g., spring and fall. For example, a conventional system
would release some heat even during a day when it was not required. This
could result in overheating the space which is an energy loss. The present
system stores heat indefinitely and will only release heat when it is
required and moisture is added to the bed.
3. The dessicant is non-corrosive and allows the heating air to
p.,ss through it without the need for heat exchangers and resultant ineffi-
ciencies.
4. Relatively low charging temperatures (150) compared to sys-
tems for the storage of sensible heat. The relatively small quantity of
sensible heat produced during the charging cycle would be used for heating
the residence during and immediately after the charging period.
In the accompanying drawings,
Figure 1 is a schematic drawing of a dessicant heat storage sys-
tem of one aspect of this invention using ventilating air to utilize
latent heat;
Figure 2 is a schematic drawing of a dessicant heat storage
system of another aspect of this invention using a heat pump to utilize
latent heat;
Figure 3 is an isometric view, partially broken away, of an
energy storage container used in a system of an aspect of this invention;
and Figure 4 is a vertical section, in disassembled form, of the
energy storage container of Figure 3.
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`` 1158121
As seen in Figure 1, a line 11 leads outside air through a
mixing box 12 having controlled vanes to permit preselected air flows
and including a heat sensor 13 operatively connected thereto. Another line
14 leads to the intake side 15 of fan 16 whose exhaust 1~ is connected to
line 18. Fan 16 is a positive displacement fan having a rating of 300 -
1000 CF~. Line 18 is provided with heat sensor 19 and passes through the
evaporation side 20 of heat exchanger 21. Line 18 then passes through
rewetting box 22 provided with means 23 to rewet air. These means may be
a standard co~mercial drum-type or spray-type humidifier. Line 18 then
passes through a heater box 24 provided with a means 25 to heat air. These
means 25 are preferably a resistance heater rated at 10 - 30 KW. A third
heat sensor 26 is provided in line 18 just before line 18 enters the
intake 27 of the dessicant bed 28. A structure and configuration of one
embodiment of dessicant bed will be described in greater detail hereinafter
with reference to Figures 3 and 4.
The outlet 29 of the dessicant bed 28 leads to line 30, and is
provided, near outlet 29, with a fourth heat sensor 31. Line 30 leads to
the condensation slde 31 of heat exchanger 21. Any moisture in the air
which condenses out is collected in tray 32, to be reused as will be des-
cribed hereinafter. Then, line 30 leads to a mixing box 33 provided withcontrolled plates to permit selected air flow. Mixing box 33 is provided
with a fifth heat sensor 34.
Two lines branch off from mixing box 32. One line, 35
leads to mixing box 12 where vanes therein can recirculate the
air through the system via fan 17 and line 18. A second line,
36, is controlled by vanes to lead to furnace 37. Furnace 37 is
provided with a flow line 38 connecting line 36 with the intake
39 of furnace fan 40. The furnace fan 40 may include a positiv
displacement fan rated at 1000 CFM. The outlet 41 from the fur-
nace fan 40 is discharged at 42 to the hot air discharge duct
43. A fifth heat sensor 44 may be placed in the discharge duct 43.
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1~58121
The furnace 37 is also provided with room air return
line 44, which bifurcates to an outgoing line 45 which leads to mixing
box 12, and with recycle line 46 leading back to line 38.
In operation, for the charging or drying cycle, system
circulation of a mix of outside air and room air by means of fan 16 drives
air flowing at a rate e.g. of 300 - 1000 CFM through the evaporator side 20
of the heat exchanger 21, and then through the heating box 24 where the
temperature is raised up to a maximum of 200 C., preferably to 150 C. This
air at such temperature then passes through the dessicant bed 28 containing a
suitable dessicent (e.g., a zeolite, e.g. Zeolite 13A, Zeosorb 3.5A, Zeosorb
5.0A, chabozite, clinoptolite, erionite or mordenite) drying the dessicant
and emerging as warm moist air at a temperature of up to 200C. The warm
moist air then passes through the condensor side 31 of heat exchanger 21
where moisture is removed and the water then stored in container 32. The air,
now at a temperature of ambient up to 100 to 150~C. then is passed through
mixing box 33. If the air is to be recycled, it then passes into mixing box
12 where it is mixed with outside air (via line 11) and with return air (via
line 45) to lower its temperature. Such low temperature air is then recycled
by being forced by fan 16 through the heat exchan~er 21 to continue the cycle.
If the air is to be passed through the existing furnace 37, it
passes from mixing box to line 36 to the furnace 37.
It is to be observed that only maximum temperatures have been
given. The temperature of the air depends on the humidity thereof at various
stages within the cycle and also on the particular instantaneous stage of the
cycle, i.e. whether it is near the beginning or the end of the cycle.
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158121
The principle involved in this embodiment of this inven-
tion is that the mix of outside air and return air provides a
sufficient temperature difference across the heat exchanger to
remove moisture from the hot discharge air from the dessicant
bed. The second mixing box permits the furnace fan to draw heat
from the system when heating is required. The system is designed
to provide heat for the building during off-peak periods and to
store the heat during other periods.
The state of charge of the dessicant in the dessicant
bed 28 is determined by temperature sensors 26, 31, located at
the intake and discharge sides respectively of the dessicant bed
28. This operates on the principle that, as the dessicant bed
dries, the temperature of the discharged air rises until it almost
equals the temperature of the intake air.
In the discharge or heating cycle, on a call for heat,
both the circulation fan 16 and furnace fan 40 start up. The vane
within mixing box 12 is closed to shut off the supply of outsides
air from line 11 during the heating cycle. The air is circulated
by fan 16 through the rewetting box 22 where its moisture is
brought up to 30%-90~ and then through the dessicant bed 28 where
the dessicant therein absorbs 5-20~ of its weight of water, there-
by simultaneously drying the air and heating the air. The warm
air at a temperature up to 200C. emerging from the dessicant .
bed 28 passes in non-heat exchange relationship through heat
exchanger 21 and then is drawn off through mixing box 33 by fur-
nace fan 40. The air is circulated through the building and is
returned through lines 44 and 45 to mixing box 12 and to fan 16
to continue the cycle. The temperature of the air is controlled
by the amount of moisture deli~ered to the air by a pump 46 and a
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control valve 47 leading from container 32. To preve~t over-
heating and sensible heat loss from the dessicant bed 28, a ther-
mostat and data processor 48 is provided to anticipate the
heating requirement and to turn off the wetting system prior to
the building reaching the desired temperature. At this time,
even though the air is not being wetted, it is still passed
through the dessicant bed 28. Now the air picks up the residual
sensible heat remaining in the dessicant bed 28 for use in heating
the building. The dessicant bed 28 therefore is warm only when
heat is required, except during the period immediately after
charging. During that period, sensible heat would be drawn from
the dessicant bed 28 as required until the dessicant bed 28 cooled.
Now referring to Figure 2, room air is connected via
furnace intake line 144 to furnace 137 and then to the intake side
115 of fan 116. The exhaust side 117 of fan 116 leads via line
118 to the evaporator side 120 of a heat pump 121. The line 118
is provided with a heat sensor 119. Line 118 leads through a
reqetting box 122 having a rewetter 123 as previously described
for Figure 1. Then line 118 leads through heater box 124 con-
taining a heater 125 as described for Figure 1. A heat sensor 126
is provided in line 118 before it enters inlet 127 of dessicant bed
126 is provided in line 118 before it enters inlet 127 of dessicant bed
128. The outlet 129 from dessîcant bed 128 leads to outlet line 119 past
heat sensor 131 and through the condenser side 131 of the heat pump 121,
the condenser side 131 also including a condensation tray 132. The outlet
line 130 from condenser side 131 passes through mixing box 133. ~ixing
box 133is provided with a heat sensor 134. Two lines lead from mixing
box 132, one to line 135 to line 111 for recycling through the system and
the second line 136 to furnace line 138 to the inlet side 139 of furnace
- 12 -
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fan 140. Furnace fan 140 expels heated air through exhaust side 141 to
hot air outlet 143. Hot air outlet 143 is provided with a heat sensor 144.
In use of this system, the circulation is the same as that for
the ventilating air system described with reference to Figure 1 with the
exception that there is no outside air required to cool a heat exchanger
and to remove the moisture from the dessicant bed 128. This function is
accomplished by the use of the heat pump 121 with its evaporator section
120 in the outgoing side and its condensor section 131 in the return
side of the circuit. The heat for drying the dessicant bed in this embodi-
ment of the invention is largely supplied by the heat pump 121 with the
resistance heater 125 acting as a booster.
The discharge or heating cycle in this embodiment is identical
to that described hereinbefore for Figure 1 since the heat pump 121 does
not operate during this cycle. Consequently, no further description will
be given at this time.
Figures 3 and 4 show a typical dessicant heat sto_age
container 300. The container includes a bottom section 310, a
core section 340 and a top section 380, all contained within a
rectangular parallelepiped hollow box 311. The core section
340 is packed with a plurality of hollow cylinders 341, each
comprising an outer shell 342 and an inner shell 343, defining
a core 344, and preferably made from square mesh woven wire
cloth having 7 meshes per lineal inch of stainless steel wire
and having 38.8% open area. The shell walls are reinforced at
their mid-length and are then filled with the dessicant material
345, e.g. ~eolite.
The bottom section 310 comprises a base 312 supporting
a bottom intake plenum 313. The plenum 313 is provided with a
plurality of inlet tubular collars, the number of such collars
: :
':' ' `; ~ :
1158121
314 being equal to the number of hollow cylinders 341. The
collars 314 project into the core 344 of the hollow cylinders 341. The
plenum 313 is sealed with a bottom cap 31-5. The plenum 313 is
fed by an inlet throat 316.
Similarly, the top section 380 includes a roof 381
with a depending upper outflow plenum 382 therein. The plenum
382 is provided with a similar plurality of outlet tubular
collars 383, the number of such tubular collars being equal to the number
of the hollow cylinders 341. The collars 383 are fed from the
core 341 of the respective hollow cylinder 341. The upper
plenum 382 is sealed with a cap 384. The upper outflow plenum
382 discharges through an outlet vent 385.
The hollow box 311 comprises an inner wall 320, and
outer wall 321, preferably formed of glass fiber reinforced
plastics, with fire retardant high density insulation core 322
therebetween.
The collars, upper and lower plates, inlet and outlet
caps, and upper roof and support plates are all preferably
made from glass fiber reinforced plastic. The components are
preferably assembled with non-corroding removable fastners. All
joints are preferably made air tight with high temperature gaskets.
While the example herein describes the invention as
a retrofit to a forced air furnace, it may be used as a new
system including a forced air system. Other primary heat dis-
tribution systems may also be used. For example, a hot water
heating system including a hot air/water heat exchange system
may be used, either as a new system or as a retrofit system.
Another type of primary heat distribution system is the so-called
high velocity duct system.
- 14 -
~15812~
The system used to take advantage of latent heat
recovery may be a heat exchanger or a heat pump. As noted
before, where an air "leakage" system is selected, a heat ex-
changer would be used. Any other equivalent type of evaporator/
condensor heat transfer system could also be used.
The system is designed primarily to use the off-peak
electric power to heat the air to dry the dessicant bed. How-
ever, a heat pump may be used. Also any convenient source of
heat may be used, e.g. from engines etc. Also, solar collectors
or solar/electric heaters may be used.
.
