CA2175154A1 - Electric thermal storage apparatus and method - Google Patents
Electric thermal storage apparatus and methodInfo
- Publication number
- CA2175154A1 CA2175154A1 CA002175154A CA2175154A CA2175154A1 CA 2175154 A1 CA2175154 A1 CA 2175154A1 CA 002175154 A CA002175154 A CA 002175154A CA 2175154 A CA2175154 A CA 2175154A CA 2175154 A1 CA2175154 A1 CA 2175154A1
- Authority
- CA
- Canada
- Prior art keywords
- containers
- change material
- phase change
- delivery device
- energy storage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F5/00—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater
- F24F5/0007—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater cooling apparatus specially adapted for use in air-conditioning
- F24F5/0017—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater cooling apparatus specially adapted for use in air-conditioning using cold storage bodies, e.g. ice
- F24F5/0021—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater cooling apparatus specially adapted for use in air-conditioning using cold storage bodies, e.g. ice using phase change material [PCM] for storage
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H7/00—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release
- F24H7/02—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid
- F24H7/04—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid with forced circulation of the transfer fluid
- F24H7/0408—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid with forced circulation of the transfer fluid using electrical energy supply
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
- F28D20/021—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat the latent heat storage material and the heat-exchanging means being enclosed in one container
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
- F28D20/023—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat the latent heat storage material being enclosed in granular particles or dispersed in a porous, fibrous or cellular structure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
- F28D20/026—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat with different heat storage materials not coming into direct contact
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
- F28D20/028—Control arrangements therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D2220/00—Components of central heating installations excluding heat sources
- F24D2220/10—Heat storage materials, e.g. phase change materials or static water enclosed in a space
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/14—Thermal energy storage
Abstract
A thermal energy storage and delivery apparatus and method is disclosed which has a plurality of small metal containers containing phase change material such as paraffin wax. The containers are arranged in juxtaposition with air spaces therebetween and in layers, each layer having multiple containers and a support heating or cooling plate located under the containers. The support plate is formed with holes therethrough for the passage of ambient air around and between the containers. A control system is provided for activating the support heating or cooling plate during off-peak hours to store energy by changing the phase of the material in the containers, and heat energy is delivered to the ambient air by passing the ambient air around and between the containers to change the phase change material back to its normal phase.
Description
2 ~ 7 ~
~ T~T~T~rTRTc TTl~v~luuL~Qva~ ~Dp_VaTlTC ar~ MR'I'TTt~n This invention relates to thermal energy storage devices, and in particular to electric thermal storage 5 devices using the latent heat of phase change material for the thermal storage.
Thermal energy storage has been commonly employed in the past to store for later use heat energy in periods of 10 time where there is an over-abundance of such energy. For example, it is often desirable to store solar heat energy during the daytime, and release this heat energy later at night. In situations involving electric heating, it is often desired to produce heat energy during off-peak 15 electricity demand hours, such as at night, store this energy, and use it later in the daytime for heating purposes when electricity demand is high and the cost of electricity is highest.
The same principles apply to cooling applications. For example, heat energy can be removed to produce cold storage, and this cold storage source can be used for later cooling purposes.
The simplest method of thermal energy storage is sensible heat storage where a storage media is heated or cooled, and this stored heat energy, or the lack of it is transferred or applied at a later time where required using suitable heat exchange devices. The problem with sensible heat storage, however, is that the media used for storage purposes must be very large and this is often not practical or suf f iciently ef f icient to be worthwhile .
As an i U~G L over sensible heat storage, devices have been produced employing phase change materials as the storage vehicle, where the latent heat of fusion or the latent heat of GvclpuLelLion produces the storage. Latent heat of evaporation is not particularly desirable, because large volumes are required to contain the storage media in . . , , . _ _ _ _ _ _ _ _ _ . _ _ , .
21 7 5 1 ~4 ~ -- 2 --the gaseous phase, but nevertheless, these devices are workable. Latent heat of fusion appears to be the most promising approach. However, attempts to u~e this principle in the past have not been particularly successful.
The main problem with prior art latent heat of fusion devices is that the heat conductivity of the phase change material is 80 low that it is dif f icult to make the material change phase. Stratification or localized melting 10 or solidification occur~ and this result~ in low efficiency and possibly even dangerous situations cau~ed by uncontrolled expansion of the melting phase change material. I~hese problems can be overcome to some degree by choosing a phase change material with a relatively high 15 heat conductivity, but the melting temperature~ of these materials tends to be undesirably high and this results in efficient heat 1088 or the need for elaborate and expensive insulation technics.
It is an objection of the present invention to overcome many of the above dif f iculties by providing a plurality of discrete, small, thermal conducting containers of phase change material arranged in juxtaposition with air spaces therebetween allowing for uniform change of phase and improved ~ff; t iency.
According to one aspect of the i~vention, there i8 provided a thermal energy storage and delivery device for heating or cooling ambient air, comprising a plurality of discrete, small, thermal conducting containers arranged in juxt~position with air spaces theLc:b~ , the containers containing pha~e change material for releasing and absorbing latent heat energy to and from the containers. A
heat source is located adjacent to the containers for heating the phase change material therein to change its phase storing latent heat energy. I~eans are provided for absorbing heat energy from the containers to cool the phase _ _ _ _ _ _ _ _ _ _ . . . . .
2 l 7~54 3 _ change material in the containers and change back its phase releasing the latent heat energy. Also, means are provided for transferring the latent h~at energy to and from the ambient air.
According to another aspect of the invention, there is provided a method for storing and delivering heat energy comprising the steps of providing a plurality of small units of low thermal conductivity phase change material, 10 the material being in a first phase at room temperature.
Eleat energy is added or removed from the units to change the phase of the phase change material located therein.
Also, ambient air is passed over the units to change back the phase of the phase change material to the f irst phase .
Preferred ~ ts of the invention will now be d~scribed, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a perspective view, with the front partly broken away, of a preferred: ~ L of a thermal energy storage and delivery device according to the present invention;
Figure 2 is another perspective view with one end broken away, of the thermal energy storage and delivery device shown in Figure 1;
Figure 3 is a sectional view taken along lines 3-3 of Figure 1;
Figure 4 is a sectional view taken along lines 4-4 of Figure 1;
Figure 5 is a plan view of a support heating plate used in the embodiment shown in Figures 1 and 2;
Figure 6 is a front elevational view of the plate sllown in Figure 5;
Figure 7 is a plan view taken along lines 7-7 of 5 Figure 6 showing the lower half of the support heating plate of Figure 5;
Figure 8 is a schematic diagram of the master control circuit f or the thermal energy storage device shown in 10 Figures 1 and 2; and Figure 9 is a schematic diagram of the local circuit for activating the heating elements of the storage device of Figures 1 and 2.
Referring firstly to Figures 1 and 2, a preferred : ' I; t of a thermal energy storage and delivery device i9 generally indicated in these drawings by reference numeral 10. For the purposes of this disclosure, the term 20 "storage device" will be used to describe this apparatus, but the apparatus not only stores heat energy, it delivers it at a later time when desired. Further, the apparatus can be used for cooling, in which case, a deficiency or lack of heat energy is actually stored and this is used later to 25 absorb heat to result in a cooling effect. The term ~storage device" is intended to include all of these f unctions .
Storage device lO is intended to be used as an area 30 space heater or air conditioner where heating or cooling capacity is stored during periods of low or no demand, for delivery later where the demand is higher. Preferably, the storage takes place during off-peak hours when the cost of energy input into storage device 10 is cheapest, and this 35 stored energy, or the lack of it, is used later for heating or cooling instead of the more expensive energy that would otherwise be required for this purpose at that time.
- ~ 217~
Storage device 10 includes a housing 12 having lower louvres 14 and upper louvres 16. Where storage device 10 is operated as an air heater ambient air f lows in through lower louvres 14 as indicated by arrow 18 and this air 5 f lows out through upper louvres 16 as indicated by arrow 20. Where storage device 10 is operated as a cooling device, this air flow direction could be reversed. Storage device 10 is located usually against a wall, in which case housing 12 would have no other air inlets and outlets than louvres 14, 16. However, if storage device 10 were used in the centre of a room, for example, additional louvres 14, 16 could be employed for the flow of air out of storage d~vice 10 in different directions. Storage device lO
preferably has 2 real or simulated marble top 22 to remain relatively cool to the touch where storage device 10 is operated es a heating device.
Referring next to Figures 1 to 4, storage device 10 includes a plurality of discrete, small, thermal conducting containers or cans 24 arranged in juxtaposition with air spaces therebetween . In the pref erred : ~; r L shown in Figures 1 to 4, there are f ive layers 2 6, each layer having three rows of thirteen cans. Containers 24 are preferably aluminum cans of the type used for beverages and are typically 12 ounce or 355 ml. cans. Cans 24 preferably are uncoated to maintain good heat conductivity through the walls thereof. As seen in Figure 3, cans 24 are filled with phase change material such as paraf f in wax 28 leaving a small air space 30 at the top of each can for expansion of the paraffin wax as it melts. Cans 24 have lids 32 that are loosely crimped to the walls of cans 24 around the peripheral edges thereof. rhese loosely crimped lids allow for venting of the cans as paraffin wax 28 expands and contracts .
As seen best in Figures 5, 6 and 7, some of the layers of cans 26 include support heating plates 34. Heating ~ ~17~t54 plates 34 include top and bottom aluminum sheets 36, 38 about 1/16 " thick with an electric heating element or wire 40 located therebetween. Holes 42 are punched in aluminum sheets 36, 38 and located between the cans as indicated in 5 Figure 5, to allow air to f low through support plates 24 between and around the cans. Heating element 40 is encased in a glass fibre, silicone-impregnated sleeve (not shown) to insulate heating element 40 from aluminum sheets 36, 38.
Heating element or wire 40 typically is a 200 watt element 10 operating at 240 volts, although other types of heating elements could be used, as desired. Aluminum sheets 36, 38 are held together by suitable metallic tape 42 or other fasteners 44.
As seen best in Figures 2, 3 and 4, only three of the layers 26 include support heating plates 34. The lower and middle plates have double rows of cans vertically stacked thereon. However, support heating plates could be provided under each layer or row of cans, if desired. The bottom 20 support heating plate 34 is elevated and supported by lower spacers 46, which could be vertical or upright zig-zag plate members as shown in Figure 2, or inverted v-shaped channel members as indicated in Figure 3. In either case, these spacers 46 are arranged 80 that air can flow under 25 the bottom layer of cans 26 as indicated by arrows 48 in Figure 3, and either up through or down from the vertically stacked cans 24. Of course, louvres 14 are in communication with the air space under the bottom layer 26 of cans.
As seen best in Figures 3 and 4, the upper portion of housing 12 includes a fan compartment 48 containing a low speed, rotary fan 50 and a standby heating element 52. Fan compartment 48 has an air inlet 54 and compartment 48 communicates with louvres 16, 80 that fan 50 can draw air through the cans 24 and force it out through louvres 16. An electrical box 56 t see Figure 3 ) contains the control 2 175t 54 ~ - ? -circuit for operating fan 50, standby heater 52 and heating elements 40 in support heating plates 34.
The walls of housing 12 are insulated with 1/2 " glass 5 fibre insulation 58 cemented to the inside of the walls and floor of housing 12 and under the upper compartments containing fan 50 and electrical box 56. Housing 12 is also provided with an access panel 59 for accessing the controls for storage device 10, such as an on/off switch and a 10 thermostat, as will be described in more detail below in connection with Figures 8 and 9.
Referring next to Figure 8, a master control circuit 60 is shown for controlling one or more storage devices 10.
15 Master circuit 60 includes a line voltage input 62 for connection to a 120 volt electrical supply. A step down transformer 64 and a rectifier 66 produces a 24 volt DC
supply to a low voltage circuit 68 represented by dotted lines. A timer 70 with an internal, normally open switch 71 20 operates a normally open relay 72. Timer 70 keeps track of real time in a 24 hour period and is programmed to close the contacts in relay 72 for a desired number of hours in a 24 hour period. Energizing relay 72 or closing the contacts therein sends a 24 volt positive DC signal to 25 tPrmin~l number 3 of tprmin~l strip 74. This also illuminates an LED 76 which, as discussed further below, indicates that one of the support heating plates 34 is energized or activated.
A Power Utility Load Reducer 78 is optionally provided for use in jurisdictions where a local electric power utility authority desires to remotely control the power demand of certain appliances owned by its customers. This is done, for example, to limit the power consumption of customers during peak load periods. When Power Utility Load Reducer 78 is activated, normally open relay 80 is energized sending positive DC voltage to termin;-l 4 of 2~7~15~
tPr~inAl strip 74 and also to illuminate LED 82 to indicate that load reduction is in effect. A master shut off switch 84 is provided to turn off the 24 volt supply to the two relays 72, 80. Naster switch 84 is normally closed when 5 storage device lO is operational. This also causes LED 86 to illuminate indicating that the system is powered on.
Switch 84 is turned on at the beginning of the heating period or season in the year, and is turned off at the end of the heating season. LED 86 typically is green in colour 10 indicating that the system is powered on. LED 76 could be coloured red to indicate that timer 70 i8 on and that storage device 10 is being heated by electrical power, and LED 82 could be coloured yellow to indicate that the local electric power utility has limited the power demand of the 15 master control circuit 60.
~ Iaster control circuit 60 could be located inside electrical box 56 in storage device 10, or it could be mounted on a wall or near an electric control panel to 20 control a number of storage devices 10.
Referring next to Figure 9, a local control circuit 9o is shown which is used to operate the support heating plates 34, fan 50 and standby heating element 52. Local 25 control circuit 90 is located in electrical box 56 or another electrical box (not shown) where local electrical codes require thi~. Each storage device 10 has a local control circuit 90 connected to a master control circuit 60 through 4-wire cable 92 connected between term;nA1 block 74 30 of master circuit 60 and tPrm;nAl block 94 in local circuit 90. Terminals 1 and 2 of tPrm;nAl strip 94 receive the 24 volt supply from master circuit 60. Terminal 3 receives the 24 volt positive signal produced by timer 70, and term;nAl 4 receives the electric power utility load reduction signal 35 from master circuit 60. A thermostat 96 is connected to tPrm;nAl~ 1 and 5 of tPrminAl strip 94. Thermostat 96 is located behind access panel 54 in storage device 10 and .
- ~ 2~ 7~
g sets the desired room temperature to be produced by storage device 10.
Local circuit 90 is connected to a line voltage supply 98 which preferably is 240 volts AC, but could be 110 volts if necessary. One side of the line voltage supply 98 is connected to each of the support heating plates 34, fan 50 and standby heater 52. The other side of the line voltage supply 98 goes to a normally open fan relay 100 and a normally open heating plate relay 102. When a timer voltage signal is supplied to t~rm;n~l No. 3 through wire 104, heating plate relay 102 is energized providing line voltage to heating plate relays 106, 108 and 110. The switches or contacts in these relays are normally closed resulting in power being supplied through t~rm;n~l block 112 to support heating plates 34. Thermistor sensors 114, 116 and 118 are coupled to support heating plates 34, 80 that if the temperature of these heating plates exceeds a pre-set limit, for example 100 to 120~ C, the respective heating plate relay 106, 108 or 110 is energized to open the switch therein and cut-of f the power to the respective heating plate. Optional LEDs 120, 122 and 124 can be provided as an indication that power is being supplied to their respective heating plates 34.
When a load reduction signal is received through load reduction signal wire 126, the normally closed load reduction relay 128 is energized causing its contacts or switch to open cutting of f power to one of the support heating plates 34, normally the top heating plate in storage device 10.
When room heatin~ is d nrled from ~torage device 10, thermostat 96 closes causing normally open fan relay 100 to be energized closing its switch or contact sending power to fan 50. This power is also sent to normally open standby heater relay 130. A thermistor sensor 132 coupled to fan 50 ,,, . _ . _ _ _ _ _ _ _ _ _ _ _ . , _ _ - . ~ 7~15~
senses the temperature of the air exiting from fan 50, and if it drops below a pr~ t~-rm; n~d temperature, for example 25~ C, standby heater relay 130 is energized sending power to standby heater 52. This may happen, for example, if 5 thermostat 96 demands more heat than the air exiting louvres 16 can provide simply by being heated by cans 24.
It can also be used to provide heat in the of f season when heating plates 34 are not normally used. A high temperature thermal switch 134 is provided to prevent 10 heating element 52 from over heating.
In operation as a heating device, containers or cans 24 contain phase change material such as paraffin wax with a melting temperature above room temperature and preferably 15 at about 62 ~ C . Support heating plates 34 are used to melt the wax in cans 24, preferably during off peak power demand periods, and this stores heat energy in cans 24 in the form of latent heat energy. The wax in containers 24 can also store sensible heat by being heated up to about 120~ C, but 20 preferably not higher than this. When heat output is required from storage device 10, thermostat 96 actuates fan 50 as described above causing air to be directed or circulated around and between containers 24 to be heated by the wax in the containers, and as the heat energy is 25 extracted from the containers, the wax therein is cooled, eventually solidifies, and gives up it latent heat energy changing back its phase to a solid. As mentioned above, if the temperature of the air output from storage device 10 drops below a comfortable level, such as 25~ C, standby 30 heater 52 kicks in to supply additional heat energy.
Although storage device 10 been described as a heating unit above, it can also be operated as a cooling unit. In this case, cans 24 would be filled with a low conductivity 35 phase change material having a melting temperature below room temperature, 80 that at room temperature it would normally be a liquid. Suitable paraffin waxes can be found ~ 2t7~
to have such a melting temperature. Instead of using heating plates 34 to melt the paraffin wax, cooling plates, which could be thermistor type devices, or evaporator plates as part of a ref rigeration system, would be used to 5 solidify the wax in containers 24. Now, cooling capacity or negative heat energy is stored in storage device 10, and when air passes through and around cans 24, the air is cooled or heat is transferred from the air to the cans causing the wax in the cans to melt and cool air to be 10 produced from storage device 10. In this case, fan 50 could be run in reverse, 80 that air is drawn in through upper louvres 16 and the cool air output comes from lower louvres 14. It may also be desirable in this instance to elevate or raise the height of storage device 10, 80 that it is closer 15 to the ceiling. Such a device could still have a standby heater 52 if desired, however, 80 that it could be operated as a cooling device in the summer and a heating device in the winter. In this case, however, the latent heat of fusion of the paraffin wax in cans 24 would not be used for 20 heating, unless the cans were replaced with a higher melting temperature wax and support plates 34 were switched over to be heating plates.
When storage device 10 is operated as a cooling 25 device, it will be appreciated that the heat source located adjacent to the containers for heating the phase change material therein to change its phase, for example from solid to liquid, is the ambient air passing around and between the cans, the air warming the cans and being cooled 30 in the process. The means for absorbing heat energy from the containers to cool the phase change material therein and change back its phase releasing the latent heat energy are the cooling plates or other refrigerating devices used to cool the cans. The means for transferring latent heat 35 energy to or from the ambient air is the spacing between the containers and the housing that allows the ambient air ~ 2~7~ 4 to pass around and between the containers transferring heat therebetween .
Having described preferred ' '; ts, it will be 5 appreciated that various modif ications may be made to the structures described above. For example, the phase change material has been described aa a paraffin wax. Paraffin wax is preferable because of its low heat conductivity, since thi6 reduces heat losses when heat transfer from or to 10 containers 24 is not desired. However, other phase change materials could be used as will be appreciated by those skilled in the art. For example, it may be possible to find a suitable liquid to gas or solid to gas phase change material and employ latent heat of evaporation for energy 15 storage. This invention is not intended to be limited by solid to liquid phase change materials.
Electric heating elements have been described as the heat sources for melting the paraffin wax. However, other 20 heat sources could be used, such as hot air or hot water if this is readily available.
The structure described above stores about 12,000 BTU's of heat energy. However, it will be appreciated that 25 the number of containers could be increased as desired to produce a storage unit with any reasonable heat capacity.
However, it may be more practical to use multiple smaller storage devices. Any number of such storage devices can be controlled by one master control circuit 60, as mentioned 3 0 above .
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modif ications are possible in the practice of this 35 invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be ~1~5~4 ~ -- 13 --construed in accordance with the aubstance defined by the .
fol~virlg cl~
~ T~T~T~rTRTc TTl~v~luuL~Qva~ ~Dp_VaTlTC ar~ MR'I'TTt~n This invention relates to thermal energy storage devices, and in particular to electric thermal storage 5 devices using the latent heat of phase change material for the thermal storage.
Thermal energy storage has been commonly employed in the past to store for later use heat energy in periods of 10 time where there is an over-abundance of such energy. For example, it is often desirable to store solar heat energy during the daytime, and release this heat energy later at night. In situations involving electric heating, it is often desired to produce heat energy during off-peak 15 electricity demand hours, such as at night, store this energy, and use it later in the daytime for heating purposes when electricity demand is high and the cost of electricity is highest.
The same principles apply to cooling applications. For example, heat energy can be removed to produce cold storage, and this cold storage source can be used for later cooling purposes.
The simplest method of thermal energy storage is sensible heat storage where a storage media is heated or cooled, and this stored heat energy, or the lack of it is transferred or applied at a later time where required using suitable heat exchange devices. The problem with sensible heat storage, however, is that the media used for storage purposes must be very large and this is often not practical or suf f iciently ef f icient to be worthwhile .
As an i U~G L over sensible heat storage, devices have been produced employing phase change materials as the storage vehicle, where the latent heat of fusion or the latent heat of GvclpuLelLion produces the storage. Latent heat of evaporation is not particularly desirable, because large volumes are required to contain the storage media in . . , , . _ _ _ _ _ _ _ _ _ . _ _ , .
21 7 5 1 ~4 ~ -- 2 --the gaseous phase, but nevertheless, these devices are workable. Latent heat of fusion appears to be the most promising approach. However, attempts to u~e this principle in the past have not been particularly successful.
The main problem with prior art latent heat of fusion devices is that the heat conductivity of the phase change material is 80 low that it is dif f icult to make the material change phase. Stratification or localized melting 10 or solidification occur~ and this result~ in low efficiency and possibly even dangerous situations cau~ed by uncontrolled expansion of the melting phase change material. I~hese problems can be overcome to some degree by choosing a phase change material with a relatively high 15 heat conductivity, but the melting temperature~ of these materials tends to be undesirably high and this results in efficient heat 1088 or the need for elaborate and expensive insulation technics.
It is an objection of the present invention to overcome many of the above dif f iculties by providing a plurality of discrete, small, thermal conducting containers of phase change material arranged in juxtaposition with air spaces therebetween allowing for uniform change of phase and improved ~ff; t iency.
According to one aspect of the i~vention, there i8 provided a thermal energy storage and delivery device for heating or cooling ambient air, comprising a plurality of discrete, small, thermal conducting containers arranged in juxt~position with air spaces theLc:b~ , the containers containing pha~e change material for releasing and absorbing latent heat energy to and from the containers. A
heat source is located adjacent to the containers for heating the phase change material therein to change its phase storing latent heat energy. I~eans are provided for absorbing heat energy from the containers to cool the phase _ _ _ _ _ _ _ _ _ _ . . . . .
2 l 7~54 3 _ change material in the containers and change back its phase releasing the latent heat energy. Also, means are provided for transferring the latent h~at energy to and from the ambient air.
According to another aspect of the invention, there is provided a method for storing and delivering heat energy comprising the steps of providing a plurality of small units of low thermal conductivity phase change material, 10 the material being in a first phase at room temperature.
Eleat energy is added or removed from the units to change the phase of the phase change material located therein.
Also, ambient air is passed over the units to change back the phase of the phase change material to the f irst phase .
Preferred ~ ts of the invention will now be d~scribed, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a perspective view, with the front partly broken away, of a preferred: ~ L of a thermal energy storage and delivery device according to the present invention;
Figure 2 is another perspective view with one end broken away, of the thermal energy storage and delivery device shown in Figure 1;
Figure 3 is a sectional view taken along lines 3-3 of Figure 1;
Figure 4 is a sectional view taken along lines 4-4 of Figure 1;
Figure 5 is a plan view of a support heating plate used in the embodiment shown in Figures 1 and 2;
Figure 6 is a front elevational view of the plate sllown in Figure 5;
Figure 7 is a plan view taken along lines 7-7 of 5 Figure 6 showing the lower half of the support heating plate of Figure 5;
Figure 8 is a schematic diagram of the master control circuit f or the thermal energy storage device shown in 10 Figures 1 and 2; and Figure 9 is a schematic diagram of the local circuit for activating the heating elements of the storage device of Figures 1 and 2.
Referring firstly to Figures 1 and 2, a preferred : ' I; t of a thermal energy storage and delivery device i9 generally indicated in these drawings by reference numeral 10. For the purposes of this disclosure, the term 20 "storage device" will be used to describe this apparatus, but the apparatus not only stores heat energy, it delivers it at a later time when desired. Further, the apparatus can be used for cooling, in which case, a deficiency or lack of heat energy is actually stored and this is used later to 25 absorb heat to result in a cooling effect. The term ~storage device" is intended to include all of these f unctions .
Storage device lO is intended to be used as an area 30 space heater or air conditioner where heating or cooling capacity is stored during periods of low or no demand, for delivery later where the demand is higher. Preferably, the storage takes place during off-peak hours when the cost of energy input into storage device 10 is cheapest, and this 35 stored energy, or the lack of it, is used later for heating or cooling instead of the more expensive energy that would otherwise be required for this purpose at that time.
- ~ 217~
Storage device 10 includes a housing 12 having lower louvres 14 and upper louvres 16. Where storage device 10 is operated as an air heater ambient air f lows in through lower louvres 14 as indicated by arrow 18 and this air 5 f lows out through upper louvres 16 as indicated by arrow 20. Where storage device 10 is operated as a cooling device, this air flow direction could be reversed. Storage device 10 is located usually against a wall, in which case housing 12 would have no other air inlets and outlets than louvres 14, 16. However, if storage device 10 were used in the centre of a room, for example, additional louvres 14, 16 could be employed for the flow of air out of storage d~vice 10 in different directions. Storage device lO
preferably has 2 real or simulated marble top 22 to remain relatively cool to the touch where storage device 10 is operated es a heating device.
Referring next to Figures 1 to 4, storage device 10 includes a plurality of discrete, small, thermal conducting containers or cans 24 arranged in juxtaposition with air spaces therebetween . In the pref erred : ~; r L shown in Figures 1 to 4, there are f ive layers 2 6, each layer having three rows of thirteen cans. Containers 24 are preferably aluminum cans of the type used for beverages and are typically 12 ounce or 355 ml. cans. Cans 24 preferably are uncoated to maintain good heat conductivity through the walls thereof. As seen in Figure 3, cans 24 are filled with phase change material such as paraf f in wax 28 leaving a small air space 30 at the top of each can for expansion of the paraffin wax as it melts. Cans 24 have lids 32 that are loosely crimped to the walls of cans 24 around the peripheral edges thereof. rhese loosely crimped lids allow for venting of the cans as paraffin wax 28 expands and contracts .
As seen best in Figures 5, 6 and 7, some of the layers of cans 26 include support heating plates 34. Heating ~ ~17~t54 plates 34 include top and bottom aluminum sheets 36, 38 about 1/16 " thick with an electric heating element or wire 40 located therebetween. Holes 42 are punched in aluminum sheets 36, 38 and located between the cans as indicated in 5 Figure 5, to allow air to f low through support plates 24 between and around the cans. Heating element 40 is encased in a glass fibre, silicone-impregnated sleeve (not shown) to insulate heating element 40 from aluminum sheets 36, 38.
Heating element or wire 40 typically is a 200 watt element 10 operating at 240 volts, although other types of heating elements could be used, as desired. Aluminum sheets 36, 38 are held together by suitable metallic tape 42 or other fasteners 44.
As seen best in Figures 2, 3 and 4, only three of the layers 26 include support heating plates 34. The lower and middle plates have double rows of cans vertically stacked thereon. However, support heating plates could be provided under each layer or row of cans, if desired. The bottom 20 support heating plate 34 is elevated and supported by lower spacers 46, which could be vertical or upright zig-zag plate members as shown in Figure 2, or inverted v-shaped channel members as indicated in Figure 3. In either case, these spacers 46 are arranged 80 that air can flow under 25 the bottom layer of cans 26 as indicated by arrows 48 in Figure 3, and either up through or down from the vertically stacked cans 24. Of course, louvres 14 are in communication with the air space under the bottom layer 26 of cans.
As seen best in Figures 3 and 4, the upper portion of housing 12 includes a fan compartment 48 containing a low speed, rotary fan 50 and a standby heating element 52. Fan compartment 48 has an air inlet 54 and compartment 48 communicates with louvres 16, 80 that fan 50 can draw air through the cans 24 and force it out through louvres 16. An electrical box 56 t see Figure 3 ) contains the control 2 175t 54 ~ - ? -circuit for operating fan 50, standby heater 52 and heating elements 40 in support heating plates 34.
The walls of housing 12 are insulated with 1/2 " glass 5 fibre insulation 58 cemented to the inside of the walls and floor of housing 12 and under the upper compartments containing fan 50 and electrical box 56. Housing 12 is also provided with an access panel 59 for accessing the controls for storage device 10, such as an on/off switch and a 10 thermostat, as will be described in more detail below in connection with Figures 8 and 9.
Referring next to Figure 8, a master control circuit 60 is shown for controlling one or more storage devices 10.
15 Master circuit 60 includes a line voltage input 62 for connection to a 120 volt electrical supply. A step down transformer 64 and a rectifier 66 produces a 24 volt DC
supply to a low voltage circuit 68 represented by dotted lines. A timer 70 with an internal, normally open switch 71 20 operates a normally open relay 72. Timer 70 keeps track of real time in a 24 hour period and is programmed to close the contacts in relay 72 for a desired number of hours in a 24 hour period. Energizing relay 72 or closing the contacts therein sends a 24 volt positive DC signal to 25 tPrmin~l number 3 of tprmin~l strip 74. This also illuminates an LED 76 which, as discussed further below, indicates that one of the support heating plates 34 is energized or activated.
A Power Utility Load Reducer 78 is optionally provided for use in jurisdictions where a local electric power utility authority desires to remotely control the power demand of certain appliances owned by its customers. This is done, for example, to limit the power consumption of customers during peak load periods. When Power Utility Load Reducer 78 is activated, normally open relay 80 is energized sending positive DC voltage to termin;-l 4 of 2~7~15~
tPr~inAl strip 74 and also to illuminate LED 82 to indicate that load reduction is in effect. A master shut off switch 84 is provided to turn off the 24 volt supply to the two relays 72, 80. Naster switch 84 is normally closed when 5 storage device lO is operational. This also causes LED 86 to illuminate indicating that the system is powered on.
Switch 84 is turned on at the beginning of the heating period or season in the year, and is turned off at the end of the heating season. LED 86 typically is green in colour 10 indicating that the system is powered on. LED 76 could be coloured red to indicate that timer 70 i8 on and that storage device 10 is being heated by electrical power, and LED 82 could be coloured yellow to indicate that the local electric power utility has limited the power demand of the 15 master control circuit 60.
~ Iaster control circuit 60 could be located inside electrical box 56 in storage device 10, or it could be mounted on a wall or near an electric control panel to 20 control a number of storage devices 10.
Referring next to Figure 9, a local control circuit 9o is shown which is used to operate the support heating plates 34, fan 50 and standby heating element 52. Local 25 control circuit 90 is located in electrical box 56 or another electrical box (not shown) where local electrical codes require thi~. Each storage device 10 has a local control circuit 90 connected to a master control circuit 60 through 4-wire cable 92 connected between term;nA1 block 74 30 of master circuit 60 and tPrm;nAl block 94 in local circuit 90. Terminals 1 and 2 of tPrm;nAl strip 94 receive the 24 volt supply from master circuit 60. Terminal 3 receives the 24 volt positive signal produced by timer 70, and term;nAl 4 receives the electric power utility load reduction signal 35 from master circuit 60. A thermostat 96 is connected to tPrm;nAl~ 1 and 5 of tPrminAl strip 94. Thermostat 96 is located behind access panel 54 in storage device 10 and .
- ~ 2~ 7~
g sets the desired room temperature to be produced by storage device 10.
Local circuit 90 is connected to a line voltage supply 98 which preferably is 240 volts AC, but could be 110 volts if necessary. One side of the line voltage supply 98 is connected to each of the support heating plates 34, fan 50 and standby heater 52. The other side of the line voltage supply 98 goes to a normally open fan relay 100 and a normally open heating plate relay 102. When a timer voltage signal is supplied to t~rm;n~l No. 3 through wire 104, heating plate relay 102 is energized providing line voltage to heating plate relays 106, 108 and 110. The switches or contacts in these relays are normally closed resulting in power being supplied through t~rm;n~l block 112 to support heating plates 34. Thermistor sensors 114, 116 and 118 are coupled to support heating plates 34, 80 that if the temperature of these heating plates exceeds a pre-set limit, for example 100 to 120~ C, the respective heating plate relay 106, 108 or 110 is energized to open the switch therein and cut-of f the power to the respective heating plate. Optional LEDs 120, 122 and 124 can be provided as an indication that power is being supplied to their respective heating plates 34.
When a load reduction signal is received through load reduction signal wire 126, the normally closed load reduction relay 128 is energized causing its contacts or switch to open cutting of f power to one of the support heating plates 34, normally the top heating plate in storage device 10.
When room heatin~ is d nrled from ~torage device 10, thermostat 96 closes causing normally open fan relay 100 to be energized closing its switch or contact sending power to fan 50. This power is also sent to normally open standby heater relay 130. A thermistor sensor 132 coupled to fan 50 ,,, . _ . _ _ _ _ _ _ _ _ _ _ _ . , _ _ - . ~ 7~15~
senses the temperature of the air exiting from fan 50, and if it drops below a pr~ t~-rm; n~d temperature, for example 25~ C, standby heater relay 130 is energized sending power to standby heater 52. This may happen, for example, if 5 thermostat 96 demands more heat than the air exiting louvres 16 can provide simply by being heated by cans 24.
It can also be used to provide heat in the of f season when heating plates 34 are not normally used. A high temperature thermal switch 134 is provided to prevent 10 heating element 52 from over heating.
In operation as a heating device, containers or cans 24 contain phase change material such as paraffin wax with a melting temperature above room temperature and preferably 15 at about 62 ~ C . Support heating plates 34 are used to melt the wax in cans 24, preferably during off peak power demand periods, and this stores heat energy in cans 24 in the form of latent heat energy. The wax in containers 24 can also store sensible heat by being heated up to about 120~ C, but 20 preferably not higher than this. When heat output is required from storage device 10, thermostat 96 actuates fan 50 as described above causing air to be directed or circulated around and between containers 24 to be heated by the wax in the containers, and as the heat energy is 25 extracted from the containers, the wax therein is cooled, eventually solidifies, and gives up it latent heat energy changing back its phase to a solid. As mentioned above, if the temperature of the air output from storage device 10 drops below a comfortable level, such as 25~ C, standby 30 heater 52 kicks in to supply additional heat energy.
Although storage device 10 been described as a heating unit above, it can also be operated as a cooling unit. In this case, cans 24 would be filled with a low conductivity 35 phase change material having a melting temperature below room temperature, 80 that at room temperature it would normally be a liquid. Suitable paraffin waxes can be found ~ 2t7~
to have such a melting temperature. Instead of using heating plates 34 to melt the paraffin wax, cooling plates, which could be thermistor type devices, or evaporator plates as part of a ref rigeration system, would be used to 5 solidify the wax in containers 24. Now, cooling capacity or negative heat energy is stored in storage device 10, and when air passes through and around cans 24, the air is cooled or heat is transferred from the air to the cans causing the wax in the cans to melt and cool air to be 10 produced from storage device 10. In this case, fan 50 could be run in reverse, 80 that air is drawn in through upper louvres 16 and the cool air output comes from lower louvres 14. It may also be desirable in this instance to elevate or raise the height of storage device 10, 80 that it is closer 15 to the ceiling. Such a device could still have a standby heater 52 if desired, however, 80 that it could be operated as a cooling device in the summer and a heating device in the winter. In this case, however, the latent heat of fusion of the paraffin wax in cans 24 would not be used for 20 heating, unless the cans were replaced with a higher melting temperature wax and support plates 34 were switched over to be heating plates.
When storage device 10 is operated as a cooling 25 device, it will be appreciated that the heat source located adjacent to the containers for heating the phase change material therein to change its phase, for example from solid to liquid, is the ambient air passing around and between the cans, the air warming the cans and being cooled 30 in the process. The means for absorbing heat energy from the containers to cool the phase change material therein and change back its phase releasing the latent heat energy are the cooling plates or other refrigerating devices used to cool the cans. The means for transferring latent heat 35 energy to or from the ambient air is the spacing between the containers and the housing that allows the ambient air ~ 2~7~ 4 to pass around and between the containers transferring heat therebetween .
Having described preferred ' '; ts, it will be 5 appreciated that various modif ications may be made to the structures described above. For example, the phase change material has been described aa a paraffin wax. Paraffin wax is preferable because of its low heat conductivity, since thi6 reduces heat losses when heat transfer from or to 10 containers 24 is not desired. However, other phase change materials could be used as will be appreciated by those skilled in the art. For example, it may be possible to find a suitable liquid to gas or solid to gas phase change material and employ latent heat of evaporation for energy 15 storage. This invention is not intended to be limited by solid to liquid phase change materials.
Electric heating elements have been described as the heat sources for melting the paraffin wax. However, other 20 heat sources could be used, such as hot air or hot water if this is readily available.
The structure described above stores about 12,000 BTU's of heat energy. However, it will be appreciated that 25 the number of containers could be increased as desired to produce a storage unit with any reasonable heat capacity.
However, it may be more practical to use multiple smaller storage devices. Any number of such storage devices can be controlled by one master control circuit 60, as mentioned 3 0 above .
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modif ications are possible in the practice of this 35 invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be ~1~5~4 ~ -- 13 --construed in accordance with the aubstance defined by the .
fol~virlg cl~
Claims (24)
1. A thermal energy storage and delivery device for heating or cooling ambient air, comprising: a plurality of discrete, small, thermal conducting containers arranged in juxtaposition with air spaces therebetween, said containers containing phase change material for releasing and absorbing latent heat energy to and from the containers; a heat source located adjacent to said containers for heating the phase change material therein to change its phase storing latent heat energy; means for absorbing heat energy from said containers to cool the phase change material in the containers and change back its phase releasing said latent heat energy; and means for transferring said latent heat energy to and from the ambient air.
2. A thermal energy storage and delivery device as claimed in claim 1 wherein said phase change material is a low heat conductivity phase change material having a melting temperature above room temperature.
3. A thermal energy storage and delivery device as claimed in claim 2 wherein the heat source includes means for heating the containers to melt the phase change material therein, and wherein the means for transferring said latent heat energy includes means for passing the ambient air around and between the containers.
4. A thermal energy storage and delivery device as claimed in clam 3 wherein the heat source includes an electric heating element located under the containers.
5. A thermal energy storage and delivery device as claimed in claim 3 wherein the heat source is hot air.
6. A thermal energy storage and delivery device as claimed in claim 3 wherein the heat source is hot water.
7. A thermal energy storage and delivery device as claimed in claim 1 wherein said phase change material is low conductivity phase change material having a melting temperature below room temperature.
8. A thermal energy storage and delivery device as claimed in claim 7 wherein the heat source is ambient air, and wherein the means for absorbing heat energy from the containers are cooling plates located adjacent to the plates to cool the containers and solidify the phase change material therein.
9. A thermal energy storage and delivery device as claimed in claim 1 wherein the phase change material is paraffin wax.
10. A thermal energy storage and delivery device as claimed in claim 1 wherein the phase change material is a paraffin wax having a melting temperature of about 62° C.
11. A thermal energy storage and delivery device as claimed in claim 9 wherein said containers are aluminum cans.
12. A thermal energy storage and delivery device as claimed in claim 11 wherein said heat source is a support heating plate, said cans being located on said support heating plate, and wherein the means for transferring latent heat energy is a housing for directing ambient air around and between the cans.
13. A thermal energy storage and delivery device as claimed in claim 12 wherein said cans and support heating plate form a first layer, and further comprising a plurality of vertically stacked layers similar to said first layer.
14. A thermal energy storage and delivery device as claimed in claim 12 wherein said support heating plate includes an electric heating element.
15. A thermal energy storage and delivery device as claimed in claim 12 or 13 wherein said support heating plate is formed with holes therethrough for the circulation of an air around the cans.
16. A thermal energy storage and delivery device as claimed in claim 11 wherein said cans have a volume of about 355 ml.
17. A thermal energy storage and delivery device as claimed in claim 12 or 13 wherein said support heating plate is formed of two planar heat conducting plates and an electric heating element located between and in contact with both plates, said plates being formed with holes therethrough for the circulation of air through the plates and around the cans.
18. A thermal energy storage and delivery device as claimed in claim 4 or 14 and further comprising a control circuit connected to the heating element, the control circuit including a timer to operate the heating element only during off-peak hours.
19. A thermal energy storage and delivery device as claimed in claim 3 wherein the means for directing fluid around the containers is a housing, said housing having an outlet for the emergence of said ambient air, and further comprising a standby heater for increasing the temperature of said emerging ambient air if it drops below a predetermined temperature.
20. A method of storing and delivering heat energy comprising: providing a plurality of small units of low thermal conductivity phase change material, said material being in a first phase at room temperature; adding or removing heat energy from said units to change the phase of the phase change material located therein; and passing ambient air over said units to change back the phase of the phase change material to said first phase.
21. A method as claimed in claim 20 wherein the phase change material is paraffin wax having a melting temperature above room temperature.
22. A method as claimed in claim 20 wherein the phase change material is paraffin wax having a melting temperature below room temperature.
23. A method as claimed in claim 21 or 22 wherein the units of phase change material are under 500 ml.
24. A method as claimed in claim 21 or 23 wherein heat energy is added to the phase change material by providing an electric heating element, said element being activated during off-peak hours of electrical power demand.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002175154A CA2175154A1 (en) | 1996-04-26 | 1996-04-26 | Electric thermal storage apparatus and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002175154A CA2175154A1 (en) | 1996-04-26 | 1996-04-26 | Electric thermal storage apparatus and method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2175154A1 true CA2175154A1 (en) | 1997-10-27 |
Family
ID=4158086
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002175154A Abandoned CA2175154A1 (en) | 1996-04-26 | 1996-04-26 | Electric thermal storage apparatus and method |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2175154A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013003886A1 (en) * | 2011-07-01 | 2013-01-10 | The University Of Tasmania | Personal cooling unit using phase change material |
| US9422060B2 (en) | 2011-01-11 | 2016-08-23 | Bae Systems Plc | Turboprop-powered aircraft with thermal system |
| US9429076B2 (en) | 2011-01-11 | 2016-08-30 | Bae Systems Plc | Turboprop-powered aircraft with thermal system |
-
1996
- 1996-04-26 CA CA002175154A patent/CA2175154A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9422060B2 (en) | 2011-01-11 | 2016-08-23 | Bae Systems Plc | Turboprop-powered aircraft with thermal system |
| US9429076B2 (en) | 2011-01-11 | 2016-08-30 | Bae Systems Plc | Turboprop-powered aircraft with thermal system |
| WO2013003886A1 (en) * | 2011-07-01 | 2013-01-10 | The University Of Tasmania | Personal cooling unit using phase change material |
| EP2726807A4 (en) * | 2011-07-01 | 2015-04-08 | Law Teen Onn Tim | Personal cooling unit using phase change material |
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| EEER | Examination request | ||
| FZDE | Discontinued |