CA1038176A - Thermal storage systems - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Disclosed are suitably structured storage means which substantially eliminate blending problems in thermal storage systems. More particularly is disclosed floatable baffle and flexible diaphragm means for preventing blending of different temperatures of water in a storage tank. Also disclosed is a thermal storage system wherein the tanks are at the base of a building and which includes the use of energy conserving turbines to further enhance the benefits of thermal storage. Direct pumping entry of the storage water at a low pressure is permitted into the load circuit which is at a substantially higher pressure and the turbine conserves energy required in the pumping.

Description

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This invention relates t~ thermal storage tank means and more particularly to anti-blending devices in the storage tank means, to the use of such tank means in cyclic heating and cooling systems and to energy conservation aspects within such systems.

BACKGROUND
Thermal storage offers significant potential for coping more economically with cyclic heating and cooling loads in buildings. Thermal storage concepts are intimately associated with the energy conservation field. With to-day's energy problems, consideration of the advantages to be gained from thermal storage, properly implemented, is essential.
Heating storage can be effected by storing surplus heat from an occupied period in a building for reuse during an unoccupied interval. Where fuel rates for generated heat are higher than energy rates for reclaimed heat, storage can reduce heating costs.
Those skilled in the art to which this invention relates will appreciate that a typical heat gain-loss chart for a building having heat reclaim and a changeover point of about 10 ~. illus-trates the immense amount of heat surplus in a building every yeal:
compared with the amount of heat required to be generated. With an appropriately designed thermal storage system in a building having a 10 F. changeover, there could be upwards of 67% of the generated heat requirement provided out of the thermal cushion for a 50 F. differential. A significant saving in fuel costs may be made.
Cooling storage permits the use of smaller chillers, which can regenerate storage during unoccupied intervals of a building - and derive help from it for occupied hours. This does nothing to reduce daily requirements of the cooling load but it does reduce D -1- ~.

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chiller demand. If one took a typical chiller demand curve (chiller demand-% vs time of day) and straightened it out over 24 hours one would find that a chiller machine of less than 50% the size required on the typical office building load and going flat out would develop about the same ton/hours as the typical machine. The smaller machine demands less electricity at any one period of time and for demand sensitive electric rates, the seasonal cost of cooling energy can be reduced significantly. For example~ in Ontario, a demand reduction in electricity of 30O/o in a typical community would provide about a 20% saving in the power bill for electric cooling.
The saving would be even greater, about 32%, in Toronto. At least 90% of the communities in Canada are demand sensitive with regard to electricity costs.
Buildings themselves provide their own storage which can be used advantageously if the control system is designed for that purpose. For example, in cooling seasons, the building can be used to reduce cooling demand if the mass is precooled over-night and the temperature allowed to rise through accep-table limits during occupied hours. Building storage varies,but cooling demand can be reduced by up to 20% if average space temperature in the building is allowed to rise by l/2F. per hour through the occupied periods of the day. Building mass is also available to reduce heating cost through use of solar gain during the day.
The use of water storage tanks properly incorporated with a heating and cooling system for a building provide an even more effective means of conserving energy through thermal storage. Such systems, in concept, store water in tanks at . ' ' ' ' -, ~ . ~ , ' ' 10381~
preselected temperatures which ~ter is drawn out of storage during occupied periods of the building to supplement the demands of the system at that time, return water of the system being pumped back into the storage tank. During unoccupied pe-riods of the building, the system continues to run primarily for the purpose of returning the stored return water to the pre-selected temperature for the next day cycle. The cost of stor-age tanks does not have to be an extra cost. There is a trade off in being able to purchase a smaller less expensive chiller.
10 Furthermore, with demand sensitive electricity rates and the ~-potential saving in fuel, the use of thermal storage can pay for itself over a relatively short period of time.
However, in the past, such systems have not met with much practical success. One of the primary problems has been - the temperature blending of water in the storage tanks and al-though there may be cases where blending exacts no penalty (or is even desirable), there are many situations where blending can -nullify the benefits of thermal storage. For example, consider the case of storage used to provide 42F. water for a daily cooling cycle. Blending from returning 60F. water, if permit-ted, would preclude the latent value of the chilled water long before the sensible cooling effect of the storage was exhausted.
Systems which have depended on the principle of buoyancy for anti-blending have been unsuccessful and this is particularly true of chilled water in the 40F. to 60F. range, where the buoyancy effect of water is at its least. Another problem is encountered in using'a thermal storage system wherein the stor-age tanks are at the bottom or are bottomside of a multi-storey building. The pressure in a chilled water line, for example at the top of the building, may be about 35 psi whereas at the bot-tom of the circuit, the pressure due to static regain may be a-bout 150 psi. The pressure in the storage tank circuit may only be about 30 psi or lower. It is possible to separate the hy-draulic head of the building from the open storage through the D

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- . - . -use of a convertor in which case the piping circuit of the stor-age tank means and the piping circuit of the load circuit are separate, each with their own pump means and thermal energy is transferred from the storage tank circuit to the load circuit through the convertors (heat exchangers). However, such con-vertors are somewhat masSive, require significant space and are expensive. Furthermore, the convertors use up a vital 5F. of a narrow cooling storage range.
SUMMARY OF THE INVENTION
It is an aspect of this invention to provide suitably structured storage tank means which substantially eliminate blending problems in thermal storage systems.
It is a further aspect of this invention to provide an appropriate bottomside thermal storage system which includes the use of energy conserving turbines to further enhance the bene-fits of thermal storage and which permits direct entry of the storage water at a low pressure into the load circuit which is at a substantially higher pressure.
The invention in one broad aspect comprehends a thermal storage system for holding varying volumes of different temperatured water which includes at least one tank means and means for separating the tank into first and second variable volume chambers and for preventing blending of different temperatured water between the chambers. The system further includes conduit means for selectively feeding water into and removing water from each of the chambers, with the separating means moving in the tank means in accordance with the feeding and withdrawal of water from the chambers whereby the volumes of water in each chamber may vary but the total volume of water in the tank means remain substantially constant. Preferably, the anti-blending means for separating the tank means into the chambers comprise an impervious flexible membrane having pe-ripheral edges which are secured about portions of respectively . .

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contiguous peripheral walls of the tank means to divide the tank means into the two variable volume chambers. The flexible membrane is in the shape of a bag whereby when water at one temperature is removed from one chamber while a substantially equivalent amount of water at a second temperature is fed into the other chamber the membrane moves to accommodate the varying volumes of different temperatured water within the tank, the total volume of water in the tank at any time being substantially constant. The flexible membrane prevents blending of the two different temperatured water within respective chambers.
The invention also comprehends a system for conditioning a load to a predetermined temperature wherein the load is in a water piping circuit. The system includes pump means for pumping water about the circuit, heat transfer means for condition- -ing water in the circuit prior to the load to a second predeter-mined temperature in order to condition the load to the first predetermined temperature, and thermal storage means including means for separating the thermal storage means into variable volume chambers. The chambers include a first chamber capable of storing water substantially at a third predetermined temperature and a second chamber capable of storing water at a fourth temperature.
Means are provided for selectively withdrawing water of the third temperature from the first chamber and introducing it into the circuit in order to maintain the second predetermined water temperature. Means are also provided for permitting a substan-tially equivalent amount of water to flow into the second chamber and be retained therein' at the third temperature. The means for separating the thermal storage means into the first and second variable volume chambers prevents blending of water at the sub-stantially third predetermined temperature with water at thefourth temperature and varies the volume of the first and second chambers in response to water withdrawn therefrom and flowing thereinto. Means are provided for selectively regenerating the first chamber with water at the substantially third predetermined ~ :

1038~6 temperature so that the thermal storage means may contain substantially all water at the substantially third predetermined temperature. Preferably, the separating and anti-blending means in the system is the flexible membrane.
The invention further contemplates the above conditioning system wherein water pressure in the circuit including the load is at a first pressure and water in the thermal storage means is at a second pressure substantially lower than the first pressure. The means for selectively withdrawing water from the first chamber and introducing it into the load circuit includes further pump means, and the means for permitting a substantially equivalent amount of return water to flow into the second chamber includes turbine means through which water from the load circuit passes. A prime mover, such as an electric motor, is operatively connected to the further pump means. The turbine is also operat-ively connected to the prime mover whereby energy required to pump water from the second pressure to the first pressure is conserved through flow of return water through the turbine means.
Other aspects and objects of the invention will become apparent from an appreciation of the detailed description herein.

10381~6 BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic diagram of a piping circuit suitable where the storage tanks are topside.
Figure 2 is a schematic diagram of a piping circuit suitable where the storage tanks are bottomside.
Figure 3 is a cross-sectional view of a storage tank showing a movable baffle.
Figure 4 i5 a perspective view of the storage tank as shown in Figure 3.
Figure 5 is a plan view of the storage tank of Figure 4 showing the guide mechanism.
Figure 6 is a cross-sectional view of a storage tank with a plurality of movable baffle anti-blending devices and capable of handling water suitable for either heating, cooling or both modes of conditioning a building.
Figure 7 is a pictorial view of a storage tank having a diaphragm baffle anti-blending device.
Figure 8 is a partial view of means for securing the diaphragm baffle to the tank walls.
Figure 9 is a schematic diagram of a piping circuit showing a topside location for the storage tanks and the inter-connection thereof to a heating circuit and a cooling circuit for a multi-storey building.
Figure 10 is a schematic diagram of a piping circuit showing a bottomside location for the storage tanks and the interconnection thereof to both a heating and a cooling circuit for a multi-storey building.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now referring to the drawings and, particularly, Figures 1 and 2, Figure 1 schematically illustrates piping ~ ' ' .
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circuitry for conditioning a load wherein the storage tank is above or substantially level with the level of the load. Figure

2 schematically illustrates piping circuitry for conditioning a load wherein the storage tank is at a location significantly below the level of the load.
Referring particularly to Figure 1, the circuit 12 schematically shown may be adapted for conditioning, that is by either heating or cooling, a load 14 which load 14 designates the total load to be conditioned and the equipment thereof. For the sake of further description of the circuitry of Figure 1, it will be assumed that load 14 represents a building to be conditioned.
Accordingly, the circuit of Figure 1 may be adapted for either heating or cooling a building. If the concept of the circuit is adapted for cooling, load 14 represents the total cooling load `-required by the building spaces to be conditioned and the equip-ment to handle such. -~
On the other hand, it will be appreciated that if the principle of circuit 12 is adapted for heating, load 14 represents - the total heating load required by the particular building and the equipment to handle such. For example, in a heating mode, load - 14 represents perimeter radiation units whereas in a cooling mode, load 14 represents fresh air handling means and compartment units of a compartmentalization air conditioning system.
A bypass circuit 16, shown in dotted lines, removes the load 14 from the water circuit and the location of appropriate ; isolation valves (not shown) to accomplish this as desired will be appreciated by those skilled in this art. Water pump 18 pumps water through the circuit and is connected to the water inlet side of load 14 by suitable piping denoted as 20. A heat transfer .

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~038~76 means 22 is connected to pump 18 through suitable piping denoted as 24 and is connected on the other side to the return water side of load 14, through suitable piping denoted as 26 and 28. Heat transfer means 22 represents a chiller in a cooling mode whereas in a heating mode, it represents means for providing heat to the water in the circuit and could be a clean condenser. Heat transfer means 22 has not, for the sake of clarity and circuitry simplicity, been shown associated with another water circuitry (such as a cooling tower in a cooling mode) although those skilled in this art will appreciate that thi s omission, or the omission of other non-essential aspects of such circuitry do not detract from the utility of the schematically represented water circuitry.
A thermal storage tank 30 is connected to piping 26 through a suitable piping denoted as 32 and 34, these pipings connecting to tank 30 at opposite sides or ends thereof and pipe 32 connecting with piping 26 via a three way temperature respon-sive control valve 36. The thermostat 38 for valve 36 is located in line 26 before the heat transfer means 22. Between - 20 lines 32 and 34 and shown in dotted lines are crossover lines 40 and 42 and valves 44, 46, 48 and 50 provide for appropriately connecting and directing water through these lines as desired and as indicated more fully hereinafter. Storage tank 30 is closed and includes an anti-blending membrane 54 which is secured peri-pherally about the sides, bottom and top of tank 30, intermediate the ends thereof, to effectively separate tank 30 into two distinct chambers 55 and 57. As more fully set out hereinafter, membrane baffle 54 is constructed such that it can assume positions at the respective ends of tank 25 such as shown by dotted lines 56 . .
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10;~ 6 and 58 in Figure 1 in addition to positions such as that shown in solid line.
Now considering the operation of the water circuitry in Figure 1, for example in a cooling mode, we can assume that during the day when cooling is required, the temperature of the water entering cooling load 14 and therefore leaving the heat transfer means (chille~ 22 must be about xF. (e.g. 42F.) whereas the return water leaving cooling load 14 is about yF. (e.g. 60F.).
In accordance with aspects of this invention, we have, however, si~ed heat transfer means (chille~ 22 so that it is only capable of cooling water of ~ + yj/2F. (e.g. 51F.) down to xF. Storage tank 30 has some water at about XoF. and this is blended with some yF. in line 26 to provide ~ + yj/2~. water entering chiller 22.
The amount of xF. water from storage 30 used to accomplish this blending equals the amount of yF. which bypasses line 26 and enters the right hand side of storage tank 30 via pipe 34. This using up of xF. water on one side of membrane 54 and the repla-cement of that amount of water by yF. water on the other side of membrane 54 continues (provided the system including the tank has been properly designed) until the cooling load is no longer requi-red, for example, at about 6.00 p.m. when people or the majority of them have left for the day. At that time or thereabouts, the appropriate valves are operated to effect bypassing of the cooling load 14 through piping 16 and valves 44 and 50 are shut with valves 46 and 48 being opened. The heat transfer means (chiller) 22 continues to operate, cooling ~ + ~/2F. water to xF. which chilled water bypasses load 14 and continues in pipes 28 and 26.
However, because of the switch in crossover valves 44-50, yF.
water flows from tank 30 through pipes 34, 42 and 32 to temperature ' ' - . ' . - . . : ' - : . . : : :
, 10381~t6 respOnsive valve 36 which blends the yF. water from storage with xF. water in line 26 to ~ + ~/20F. water, acceptable for chiller 22. Some of the xF. water in line 28 continues through lines 34, 40 and 32 to the left hand side of storage tank 30. It will be appreciated that the running of the system in this manner overnight (that is for example until 6.00 a.m. or thereabouts, or until all yF. water has been replaced in the storage tank with xF.
water) replenishes the storage tank 30 with water at a tempera-ture which will be available during the next day cycle, (the crossover lines having been switched back and the load brought on) to assist or help the heat transfer means (chiller) 22 provide adequate building cooling.
As an alternative to crossover piping 44 to 50, the circuitry could, for example, eliminate the need for same by having piping 60 shown in a dot-dash line (isolation valves not shown) which when put on line through operation of appropriate valves in line 20 (not shown) would direct the water back to line 32. A portion of the water would be pumped to storage 30 and a portion would be throttled through blending valve 36 to provide ~ + y~/2F, water entering heat transfer means 22 when blended with yF. water coming via piping 34 and 26 from the other side of membrane 54 of storage tank 30.
Persons skilled,in the art will appreciate the adaptability of the circuit 12 in a heating mode in which case the water tempe-rature xF. will be higher than yF. temperature water and the blending of water by valve 36 will be responsive to the t~mperature for which thermostat38 is set and the designed handling capabilities of heat transfer means22 in such mode. The provision of auxiliary heating means in circuit 12 is contemplated if necessary to handle D

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10381~6 the demands of load 14 but has n~ been shown for the sake of clarity and simplicity in illustrating one of the main aspects of this invention, namely, the anti-blending membrane or diaphragm 54 of the thermal storage tank 30.
NoW referring more particularly to Figure 2, there is schematically illustrated a piping circuitry which will be discussed with respect to conditioning a load such as a building wherein the storage tank is at the bottom or base of the building being condi-tioned whereas the load is above the storage tank and the heat transfer means (e.g. the condenser or chiller) is topside the building. -~
The load circuitry 112 includes load 114 which,as previous-ly noted with reference to Figure 1, schematically represents the heating load or cooling load of the building and the equipment which handles it on a floor by floor, space by space basis, depend-ing on the mode of use of the circuitry. Bypass 116 enables the load to be bypassed and again it will be appreciated that suitable isolating valves, not shown, will be available in the piping cir-cuits to accomplish this. Heat transfer means 122 is connected 20 at its outlet end to load 114 via piping 120 and 124 and through pump 118. The inlet side of heat transfer means 122 is connected to the outlet end of load 114 via piping 126 and 128. Storage tank 130, being at the b,ottomside or base of the building being conditioned is connected to the load piping circuit, namely pipings 126 and 128,via pipings 132 and 134, the junction of piping 132 and 126 being through temperature responsive valve 136, res-ponsive to thermostat 138. The dotted crossover pipings 140 and 142 and related isolation valves 144 to 150 are present in a similar manner and for the same purpose as those shown in the load circuitry -12- ~ -l;,~i - . . ' ' . , ' , ',: - ~
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: of Figure 1. However, a pump P fs located in piping 132 in order to pump water from storage tank 130 and the storage tank circuit (which is at a low pressure such as 30 psi) into the - load circuit which at its low point in the building where the juncture of the two circuits take place may have a water pressure due to static gain of 150 psi while at the top of the building may have a pressure of only about 35 psi. Check valve 184 retains such pressure within the load conditioning circuit.
Pump P is driven by a double shafted motor M, the other shaft of motor M being connected to turbine pump T which is located in piping 134. A pressure responsive valve 180 is located in line 134 and the valve 180, with pressurestat 182 located in closed expansion chamber 186 maintains the water pressure within the load conditioning circuit at the low point at say 150 psi (and -~ therefore at the high point, about 35 psi). A check valve 188 is located in line 126 between the connections of lines 132 and 134 therewith. The expansion chamber 186 in communication with piping line 120 provides for expansion of fluid in the load circuit. In the topside circuitry 12 of Figure 1, storage tank 30 itself can provide for expansion of fluid in such circuit.

In operation, assuming cooling mode of operation for the circuit and assuming a temperature differential across the cooling load 14 of xF. to yF. (e.g. 42F. - 60F.) and a heat transfer means (chiller) capacity which can only handle the cooling of x + y/2F. (e.g. 51F.) water to xF., water temperature responsive valve 136 blends yF. water returning from load 114 via line 128 with xF. water in line 132 from one side of storage tank 130 to maintain the appropriate temperature of (x + y)/2F. in line 126 entering heat transfer means (chiller) 122. The pressure in the load conditioning circuit is , 10381 ~6 maintained relatively constant at the exemplified pressures of 35 psi at the top and 150 psi at the bottom by virtue of pressure responsive valve 180. Valve 180 opens and closes in response to a build-up or reduction in pressure in the load conditioning circuit and expansion chamber as a result of water being pumped into such circuit by pump P. The return of water at a pressure of 150 psi in the load conditioning circuit to the pressure, e.g. 30 psi, in the storage tank circuit causes operation of turbine pump T. Rotation of such turbine T and its operative connection to motor M provides an energy conserving feature to the power requirements of pump P. During non-occupied periods, for example from 6:00 p.m. until 6:00 a.m., -~
valves 144 - 150 are actuated to bring into service crossover -piping 142, 144 and load bypass 116 is brought into service.
Heat transfer means (chiller) 122 and the pumps 118 and P
continue to operate whereby xF. water replenishes the right side of storage tank 130 from heat transfer means 122 via piping 124, 120, bypass 116, piping 134 and 142. The yF. water in the left hand side of tank 130 is withdrawn through piping 134, 20 piping 140, piping 132 and is pumped into the load circuit blending with xF. water in piping 128 to provide ~x + y)/2F.
at the inlet of the heat transfer means 122. When the tank is completely regenerated, it is ready for the next day cycle supplementing chilled water in this mode of operation to the cooling load circuitry.
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Accordingly, it will be seen that with the bottomside thermal storage system of Figure 2, the use of the recovery turbine impeller linked to the same pump shaft as the pump impeller permits recovery of a substantial amount of the energy used to pump from the open storage into the closed building load D

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1(~38176 circuit. The pressure break between the hydraulic building head : and open storage is intended to take place across the turbine T
and recovery of this energy can be significant (upwards of from 60 to 80~ depending on the care with which the recovery turbine impeller is designed and controlled). Since direct introduction of storage water into the load circuit is possible, the upwards of 5 heat transfer loss using convertors has been eliminated.
Further, the energy necessary to accomplish such introduction is conserved through the turbine being operatively connected to the pump motor. Nevertheless it will be appreciated that convertors can be used as a means of isolating the pressure of water in the load conditioning circuit from the pressure of water in the storage tank circuit by means of the convertors, the convertors permitting only heat or thermal transfer between the two circuits.

It will be apparent to those skilled in the art that the schematic circuitry of Fig. 2 is also adaptable to a heating mode operation and that tank 130 would contain water in one chamber at an appropriate temperature to assist heat transfer means 122 or supply water directly to meet the demands of heating load 114.

Figures 1 and 2 depict circuitry wherein the heat transfer means is basically shown as in series with the load.
It is quite possible, however, to relocate the heat transfer means to place it, for example, in parallel at least for part of the time with the storage tanks 30 and 154 respectively without detracting from the inventive concept of the present invention.
When the heat transfer means is in parallel with the storage D

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tank, crossover lines are not required in order to regenerate the storage tank. Indeed, regeneration can take place while the heat transfer means is on line during the daytime if the capacity of the heat transfer means is greater than load demand.
This possibility will be evident from reviewing Figure 1 for example and piping means 60.

Figures 3 to 7 inclusive more fully set forth the structure of storage tanks and, in particular, the anti-blending devices for such tanks. Although it is possible to control blending to some extent through fixed labyrinth baffling means, it is not particularly efficient and a great number of baffles are necessary, with the attendant construction costs, if any significant degree of anti-blending efficiency is to be achieved.

- , ;- One embodiment of a preferred anti-blending apparatus for a storage tank is a floating baffle more particularly illus-trated in Figures 3, 4 and 5. Tank 200 has a floating baffle 202 and the tank is shown open although some covering can be provided. Baffle 202 is constructed and appropriately weighted ^ 20 by weights 204 so that it substantially floats in the water with the bottom and side edges of the baffle proximate the respective bottom and side edges of tank 200. Pipings 206 and isolation valves 208 are provided as inlet and outlet means for water in tank 200. ~affle 202 does not rest on the bottom of the tank 200 but there are preferably flexible seals 210 such as rubber flanges which ~

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would extend from the bottom ~ b~ffle 202 and touch the tank bottom. Similar type seals 212 are used on the sides of the baffle. A mechanism such as that shown more particularly ~ -in Figure 5 is used to retain baffle 202 in parallel relationship with the ends of tank 200 (and perpendicular to both sides - thereof). The mechanism includes a pulley wheel 216 suitably mounted adjacent each corner of the tank 200 with two pulley wheels 218 at each end of baffle 202. A rope or wire means 220 is anchored at each end of tank 200 at 222 and is entrained about pulleys 216 and 218 as shown, spring 224 providing a slight bias-ing and shock-absorbing means.
As shown in Figure 3, when water enters tank chamber 226, the water level in chamber 226 rises above that in chamber 228, thereby causing a greater head in chamber 226 than that in chamber 228. The differential in head causes the top portion of the baffle 202 to move to the right resulting initially in baffle 202 slanting slightly as shown exaggeratedly in Figure 3. In due course, the bottom weighted floating baffle 202 will again assume a vertical position but to the right slightly of its previous position. Accordingly, the baffle 202 floating in tank 200 "walks~ back and forth from end to end of tank 200 effectively maintaining the water level in chambers 226 and 228 of the tank substantially the same although the volumes of the chambers will vary significantly.
It will of course be appreciated that storage tank 200 is in a closed water system and the level of water and therefore the volume of water in the tanks as a whole remains substantially constant at all times and it is on this basis and with this in mind that the floating baffle is designed. When water is drawn ' 1~38176 from one chamber, for example, cha~ber 226, water is put into chamber 228, the only difference is that the water on each side of baffle 202 is at a different temperature. The pressure difference across baffle 202 at any one time is very slight as baffle 202 is constantly adjusting its position relative to the ends of the tank 200 to equalize the pressure in the cham-bers. Accordingly, actual leakage of fluid between chambers 226 and 228 around baffle 202 and seals 210, 212 is minimal and thermal leakage is kept to a minimum through using insulating material such as styrofoam for or as a part of the baffle 202. The tank itself is also preferably insulated with insulating material such as styrofoam or the like. A preferred insulating material is foam glass which is a close cell material which never absorbs water and can be used to line the tank as well as insulate the outside.
Figure 6 shows a tank 230 having three, bot~om weighted but floating baffles 232, 234 and 236. Tank 230 serves to store both water for the heating system and water for the cooling cycle.
To the left of center baffle 234 is the heating water storage section 238 whereas the cooling water storage section 240 is to 20 the right as shown in Figure 6. Pipings 250, 251 act as water inlet and outlet means with regard to the heated water storage section 238 and pipings 252, 253 provide water inlet and outlet means with regard to cololing storage section 240; isolation valves --242 are provided for obvious reasons. It will be appreciated by those skilled in this art that there are times during a year when more heating water will be required than cooling water and vice versa. Indeed during the Summer periods probably all the tank will be dedicated to cooling water and middle baffle 234 would be moved as far left as possible (along with baffle 232). During --18 _ - : ~ , ~ '. , . :.' :

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Winter periods, the tank could be dedicated to heating water primarily, with only a small portion of the tank dedicated to - cooling. In this latter case, baffle 234 would be moved as far right as required by the minimal cooling load (along with baffle 236). In order to move baffle 234 a small pump 244 and piping circuitry 246 shown bounded by a dotted line which includes various valves 247 is provided so that the total amount of water in section 238 may be altered relative to that in section 240 and vice versa. Piping lines 248 and related valves 249 provide tapping into various portions of the tank in order to provide suitable connection with pipings 251, 252 depending where baffle 234 is. In this manner, it will be apparent that one can dedicate tank 230 to more or less heating or cooling as demand requires during the various seasons during a year. With this type of set up a single tank could provide adequate storage facilities regardless of whether the demand requirement is - primarily for heating water, cooling water or both during intermediate seasons, where one is working from both ends of the tank 230. The decision to shift intermediate baffle 234 would be that of the operator of the system depending on his decision - as to heating and cooling requirements of the systems at the particular period of year, although the location of the baffle 234 for any particular system could be computerized. Baffles 232 and 236 each operate in the same manner as baffle 202 in Figure 4.
Figure 7 shows a second embodiment of a preferred form of baffle which has already been shown schematically in Figures 1 and 2. Tank 260 is shown with an impervious flexible membrane baffle 262 secured to the bottom sides and top (shown removed) of tank 260 intermediate the length of tank 260. Membrane baffle 262 is preferably constructed and sewn into a rectangular (bag) shape in order that it may assume a shape close to that of the tank. The membrane is preferably constructed of a DACRON ~ -fibre net covered on both sides with HYPOLON ~ . The membrane is approximately water weight. Other materials such as nylon coated with various plastics or materials such as PVC or TEFLON ~ may be used. The open end of the membrane is sealed against the center line of the tank 260 across the top and bottom and up the sides. Figure 7 illustrates the membrane extended toward one end position of tank 260 but it will be appreciated (as shown in Figures 1 and 2) that membrane 262 will assume a random position intermediate the ends of the tank 260 physically separating tank 260 into two chambers. The actual - means of securing the membrane to the tank walls is not significant but a method of doing same is shown in Figure 8. -The tanks referred to in this disclosure are preferably of concrete and it will be appreciated that in pouring the concrete for the tanks an anchor device 264 such as that shown in Figure 8 may be partially embedded into the concrete at the . .
- appropriate location about the top, bottom and sides of the :
tank. The anchor device is basically "T" shaped in cross section with flange 266 secured in concrete and the bulbous end 20 268 extending into the tank. Membrane 262 has a bifurcated edge 270 which encloses bulbous end 268 and is secured on opposite sides of portion 271 of device 264 by means of through washered bolts 272 or other equivalents. Although, the flexible membrane has been shown as moving horizontally from end to end in Figures 1, 2 and 7, it will be obvious that it may be secured to the walls of thetank in such manner as to move vertically from top ~ ` -to bottom and in some systems where extremely large tanks are contemplated this could be preferred.
Figure 9 illustrates a thermal storage circuit wherein 30 the storage tanks 300 and 302 are topside. There are two storage tanks although there could be more and each can be dedicated to heating storage (50F. to 100F. range) or cooling storage (42F. to 60F.). Valves Al to A4 are isolation valves - , ' ' . '' ' ~ '' ':
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to isolate each compartment f~r servicing, or when it is desired to draw from or use only one storage tank. However, these valves are normally open. Valves Bl to B6 segregate the supply and return headers 304 and 306 so that any one or all of the storage tanks can be dedicated as desired to heating or cooling (or if there are more than two storage tanks, in any combination). Valves Cl - C4, which can be automated in order to be centrally controlled, permit water to be supplied to or withdrawn from either side of the tank diaphragms.
The circuit of Figure 9 schematically provides for eonditioning a multi-storey building and includes a heating water eircuit 310, a chilled water circuit 312 and a tawer condensing water cireuit 314. A heat pump or chiller 316 is provided which includes a elean eondenser 318, an evaporator 320 and a tower eondenser 322. Other aspects of the refrigeration circuitry are not shown for the sake of clarity including the usual conduit bypass around the evaporator 320. Clean condenser 318 is ineluded in the heating circuit 310 which also includes an auxiliary heater 324, hot water pump 326 and heating load - 20 328. Piping 330 provides a bypass to load 328 and it will be appreeiated that appropriate isolation valving with regard to bypass 330, although not shown, would be present. Auxiliary heater 324 may provide heat direet from boilers in the building or from any other heat souree. Pipings 332 and 334 interconnect the headers 304 and 306 through valves Cl and C2 respectively to the heating circuit, piping 334 eonneeting with the heating eireuit through thermostatieally eontrolled blending valve 336.
Thermostat Th is loeated in the eireuit as shown and not only eontrols valve 336 but also eontrols the addition of heat through auxiliary heater 324 as ealled for in known fashion.
Thermostat Th is responsive to ambient temperature and Th also controls other elements as more fully set forth hereinafter.

Piping 337 provides a free heating bypass to condenser 318 and ,~

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10381~6 interconnects with the circuit prior to pump 326 through diverting valve 339.
-The chilled water circuit 312 includes the evaporator 320, a chilled water pump 338 and cooling load 340. Bypass 342 permits bypassing the cooling load and it will be appreciated - that the appropriate valving in regard to the bypass although not shown, is provided. Pipings 344 and 346 interconnect the chilled water circuit 312 with the headers 304 and 306 through valves C3 and C4 respectively, piping 344 connecting with the 10 chilled water circuit through thermostatically controlled ~ -blending valve 348. Thermostat Tc which controls valve 348 is located in the chilled water circuit before the evaporator 320.
Valve 348 is also controlled by thermostat Th in certain instances as more fully set forth hereinafter. Piping 350 bypasses load 340 and connects into piping 344, valve 352 controlling the flow through piping 350 and valve 352 is also - responsive to thermostat Tc. Tc is in the return water line from load 340 and will also control the evaporator in the preferred system which utilizes the compartmental system as 20 described in Canadian patent No. 963,258 granted to Tamblyn on February 25, 1975. Tower condensing water circuit 314 includes - tower condenser 322, pump 354 and tower 356 and the cooling capacity of the tower is controlled through the inlet damper vanes and is responsive to Th depending on the demand for heat and available heat energy in the clean condenser, in accordance with the teachings in said patent.
In operation, if the chiller capacity balances the cooling load, the chilled water will normally circulate in the chilled water circuit between the evaporator 320 and the load 340. However, in warm weather, the cooling load during the day will most likely exceed the chiller capacity. In this case thermostat TC opens valve 348 and 42F. water from storage tank 302 assuming it has already been charged is drawn through header I~
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306, valve C3 and piping 344 to blend with return water from load 340 in order to provide a water inlet temperature to the evaporator which the chiller can handle. secause of the closed system, an equivalent amount of return water (60F.) will be pushed into the right hand compartment of tank 302 through piping 346, valve C4 and header 304. If on a cool day or even during a portion of a day the chiller-evaporator at 100~ -capacity becomes larger than the load demand then auto valve 352 opens in response to thermostat Tc to permit direct recharge of the left hand side of storage tank 302 through pipings 350, 344, valve C3 and header 306, while the chiller-evaporator is on line during the day or portlon thereof. A portion of the chilled water from the evaporator is therefore utilized to directly recharge the storage while another portion is utilized to meet the cooling load at that time.
At night, when the cooling load is minimal the chiller-evaporator 36 may be run in order to recharge storage tank 302 with 42F. water. When the storage is charged, a signal (not shown) from the diaphragm position can close valve 352 to storage and the chiller can schedule downwardly automatically but continues running if it has an ongoing cooling load. If there is no continuing cooling load the chiller can be programmed to turn itself off. From the circuitry and the above, it will also be appreciated that chilled water at 42F.
could be drawn from storage without using the chiller, in order to serve small, after-hours cooling loads.
With reference to the heating operation, it will be appreciated by those skilled in this art, that in multi-storey buildings, even in Winter, a cooling load most always exists and the supplying of heat to the building is basically to balance fabric heat loss. Accordingly, the chiller is run throughout most periods of Winter and when it is being operated to cool the .

lQ381q6 interior of the building, the condenser heat is driven into the clean condenser 318 to serve the heating load 328 and balance it. If there is insufficient condenser heat to balance the heating load, then Th will call upon the auxiliary heater 324 to supplement the heat required. If, however, there is more heat being supplied to the clean condenser 318 than used in the -heating load (for example during periods of Spring and Fall) then Th will open valve 336 to piping 334 (valve 339 being open from the clean condenser) to allow surplus condensing heat to load up the left compartment of the heating storage tank 300 with hot condensing water through piping 334, valve C2 and header 3 304. Water in the right compartment of heating storage tank 300 will enter the heating circuit through header 306, valve Cl and piping 332. When the storage gets full of hot condensing water, the tower condenser circuit 314 would be controlled to automatically cut in to discharge the surplus heat unable to be -~
stored. (It will be appreciated that auxiliary heater 324 can also be adapted to supply additional heat to water being fed to storage.) At night, if water exists in any storage compartment warm enough to heat the building without being boosted by the clean condenser or auxiliary heater (e.g. 90F. - 105F. water) it can be circulated directly from storage to the heating load using the diverting valve 339 to bypass the clean condenser.
Assuming that the water used is 100F. it will be returned to the storage at a tempe~ature which may be about 85F. which, once all 100F. has been used, is not sufficient to continue heating the building. The only way to continue to adequately heat the building is to blend some of this 85F. water with other hotter water in order to raise it back to 100F. This may be done through using the chiller and it is activated to supply the clean condenser 318 as for a daytime cycle. (This assumes D
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- ~038176 that the chilier is not otherwise operating to meet a nighttime cooling load or to regenerate tank 302.) Valves Bl to B6 are appropriately activated to enable some of the 85F. water to be - drawn from storage to the cooling circuit. Enough of this 85F.
water from say the right compartment of storage tank 30 is drawn through header 306, valve C3 and piping 344 with controlled blending of this water with return water in the chilled water circuit by valve 348. The chiller, although cooling the water in the chilled water circuit is run to satisfy the heating demand through the clean condenser 316, there being no cooling load or regeneration of storage of chilled water required. Th is used to control valve 348 in this mode of operation. The other compartment (left) of the heating storage tank 300 receives the return water from the chilled water circuit through piping 346, valve C4 and header 304 (cooling load bypass 342 having been activated)~. Part of the water from storage at 85F. is valved through header 306, valve Cl and piping 332 to the heating circuit to which is added heat from the clean condenser 318 to thereby satisfy the heating demand of the building. The return hot water is also valved into the tank to which the water from the chilled water circuit is returning namely via piping 324, valve C2 and header 304. Accordingly heating demand can be met by means of operating the chiller in conjunction with the hot water storage tank, the chiller being run to provide the necessary heating through the clean condenser. The use of the heat storage tanksallows the chiller to be operated notwithstanding that there is no demand cooling load or cool storage replenishing and yet this mode of operation provides an economic heat generation means to meet heating demand.
Figure 10 schematically shows circuitry similar in concept to that of Figure 9 but directed to a bottomside location of the storage tanks and the attendant use of the . .

10381q6 energy conserving pump-turbine ~ans of supplying water from the storage tank circuit and removing water from the chilled water circuit when there is a significant pressure difference in the circuits. Like elements in Figure 10 to those of Figure 9, when considered in the context of Figures 1 and 2 have been indicated with reference numbers in the 400s.
In Figure 10, if the evaporator capacity balances the cooling load, the chilled water will normally circulate in the chilled water circuit between the evaporator 420 and the load 440. However, in warm weather, the cooling load during the day will most likely exceed the chiller capacity. In this case ;
thermostat T-cool opens valve 448 and starts motor Mc and pump Pc so that 42F. water from storage tank 402 (assuming it has been charged with this temperatured water) is pumped (diverting valves C3 and C4 being appropriately set) through header 406, valve C3 and piping 444 to blend with return water from load 440 in order to provide a water inlet temperature to the evaporator which the chiller can handle. Because of the closed system and the pumping by Pc of stored water into the chilled water circuit, the pressure in the circuit will rise. Pressurestat Psc in piping 446 is responsive to the increase in pressure and opens turbine dump valve 460 thereby permitting water which is at a high pressure in the chilled water circuit to return to the low pressure of the storage tank through turbine Tc, valve C~
and header 404, into the right hand side of tank 402. The pressure break across the turbine Tc conserves input energy required by motor M toloperate pump Pc. If the evaporator at 100% capacity becomes larger than the load demand, then direct recharging of the storage tank 402 is possible (with the setting of diverting valves C3 and C4 appropriately reversed) in a manner similar to that set out with reference to the embodiment of Figure 9. Similarly, at night the chiller-evaporator continues to run in order to regenerate the storage tank 402 with 42~F. With an appropriate bypass around evaporator 420 D
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~038176 (not shown) 42F. water if av~llable can be drawn direct from storage tank 402 without usiny the evaporator. When regeneration is complete or storage exhausted, water will be depressed in level on one side of the tank anti-blending membrane. The lower inlet pressure to the pump Pc will be its signal to stop. At this time, the turbine dump valve 460 will - close tightly.
T-heat provides the lowest radiation temperature necessary to balance the fabric loss of the building. It is mastered by an outdoor ambient temperature schedule in the usual manner. T-heat is programmed to call first upon reclaimed heat, in case the chillers are operating in the occupied or regeneration mode. This is accomplished through varying the water tower capacity with scroll dampers and fan cycling controls (not shown). When insufficient heat is available from reclaim, T-heat can control the auxiliary heater 424 to make up the balance. When condensing temperature rises, owing to the fact that necessary cooling provides more condensing water heat than can be used by the heating system at a given instant, T-heat starts the motor Mh and hot water pump Ph and the pressuresensitive turbine dump valve 464 opens. This brings cooler water from the right side of storage tank 400 through valves A2, header 406 and valve C2 into the heating load circuit through blending valve 436 and permits the storing of the excess condensing water which flows in pipe 332 to return to storage across turbine Th throuqh valve Cl, header 404 and valve Al to the left side of storage tank 400.
Eventually, the storage tank 400 will fill with surplus condensing water and the transfer pump pH will stop and the dump valve 464 close. At this point, a further rise in condensing temperature would through T-heat activate the tower condensing water system including pump 454 and operate the sequence of damper and fan cycling control which is incorporated with the tower in the usual manner.

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1038~76 Hot water may be pumped directly from storage tank 400 during unoccupied periods if it is high enough in temperature to - be useful (with an appropriate bypass (not shown) of the clean condenser being activated). This may be done by operating the hot water pump Ph in a manner noted above with return to storage through turbine Th.
When stored hot water has been used through one pass in this manner, the hot water pump pH will stop through a low pressure cut-off. Further heating may be accomplished from storage tank 400 by valving the tank 400 to feed the chilled water circuit 412. T-heat will then operate the chilled water pump Pc and allow the evaporator to provide enough heat to the ~`
clean condenser to satisfy the heating circuit similar to the ;
system shown in Figure 9.
Although Figures 9 and 10 show only two storage tanks, it should be appreciated that any number may be provided, ~ -connected in like manner to the appropriate headers. Further, during certain periods of the year, for example, Summer, it may be that the majority or all of the tanks will be dedicated by appropriate valving into a cooling mode of operation. Likewise in Winter, as the heating requirements demand, the majority of the tanks could be valved into a heating mode of operation, with the remaining tanks handling whatever cooling demand there is for stored chilled water. Further it will be appreciated as was the case in Figure 2 that convertors can be used in a system where the storage tanks are bottomside to isolate the heating and cooling load circuits from the storage tank circuits with the attendant modifications being made to the circuits. This construction eliminates any concern of the differences in pressure between the circuits.
It should be further appreciated that the basic thermal storage systems shown in Figures 1 and 2 are adaptable to various other situations other than in air conditioning a multi-storey .

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~03~1~6 - building. For example, heat tr~nsfer means of these embodiments may be solar energy means such as roof collectors for heating a home. Moreover, the heat transfer means could include an incinerator for burning garbage or be electric heating. Further-more, the flexible membrane of this invention could be used in a hot water tank system in oraer to prevent blending of incoming cold water with hot water. The membrane in this case would prevent stratification of the cold and hot water with the incoming cold water pushing out the hot water from the tank behind the membrane. With heater means in each variable volume chamber on each side of the membrane and with appropriate cross over piping and valve means, each variable volume chamber within the tank would alternate as the reservoir for the hot water or incoming cold water.
Various modifications in the circuitry involved with reference to the utilization of the flexible membrane in a thermal storage tank system are possible without detracting from the spirit of the invention set forth hereinbefore and defined in the appended claims.
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Claims (25)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a thermal storage system for holding varying volumes of different temperatured water comprising: at least one tank means, means for separating the tank into first and second variable volume chambers and for preventing blending of different temperatured water in the chambers, conduit means for selectively feeding water into one chamber while simultaneously removing water from the other chamber, said separating means moving in said tank means in accordance with the feeding and withdrawal of water from the chambers whereby the volume of water in each chamber may vary but the total volume of water in the tank means is substantially constant.

2. The system as defined in Claim 1 including a plurality of separate storage tank means said separating and anti-blending means in each tank being an impervious flexible mem-brane defining the respective variable volume chambers, and said conduit means including piping and valve means to permit any combination of said tank means to be included into a selected mode of operation for selectively withdrawing water from and permitting flow of water into respective chambers of said plurality of tank means.

3. The system as defined in Claim 1 wherein said sepa-rating and anti-blending means comprise a vertically floatable baffle, said baffle being substantially the width of said tank means and floating upright in water in said tank means with a por-tion thereof above the level of the water and the bottom and sides of said baffle closely adjacent the respective bottom and sides of said tank means, means for guiding said baffle for movement from end to end of said tank means in response to the volume of water on either side thereof, and means lightly sealing the tank bottom and sides with the respective bottom and sides of said baffle.

4. The system as defined in Claim 3 including two additional like floatable baffles, a centre one of said baffles remaining substantially stationary and separating said tank means into a hot water storage tank section and a chilled water storage tank section, the other two baffles providing respective separating and anti-blending means for said hot water storage tank section and said chilled water section, said conduit means including piping means, pump means and valve means associated with portions of said tank means whereby said centre one of said baffles may be selectively moved and the capacity of the tank means converted entirely to a hot water or cool water mode or to a selected combination thereof.

5. The thermal storage system of Claim 1 wherein said anti-blending means for separating said tank means into said chamber comprises: an impervious flexible membrane having peripheral edges which are secured about portions of respectively contiguous peripheral walls of the tank means to divide said tank means into said two variable volume chambers, said flexible membrane having a shape of a bag whereby when water at one temperature is removed from one chamber a substantially equivalent amount of water at a second temperature is fed into the other chamber, the membrane moving to accommodate the varying volumes of different temperatured water within the tank with the total volume of water in the tank at any time being substantially constant, said flexible membrane preventing blending of the two different temperatured water within respective chambers and being substantially water weight.

6. The thermal storage system of Claim 5 wherein said flexible membrane is shaped so that it substantially takes the shape of a portion of the tank when there is substantially no water in one chamber compared to the other chamber.

7. The thermal storage system of Claims 2, 5 or 6 wherein the peripheral edge of the membrane is bifurcated into two end portions, and anchor means secured to said peripheral tank walls and having inwardly directed enlarged means around which the end portions of said membrane are secured.

8. The thermal storage system of Claims 1, 2 or 5 wherein said tank means is of concrete and has means for access into the interior of said tank means and each of said chambers.

9. A thermal storage tank for use in a system for air conditioning a building, comprising walls capable of holding water at two different temperatures, means for separating the tank into two chambers each chamber for holding different temperatured water and preventing blending thereof, said separating and anti-blending means comprising an impervious flexible membrane secured about certain of said walls to form said chambers and capable of taking the shape of the walls to which the membrane is not secured, and conduit means for simultaneously feeding water to one chamber of the tank and withdrawing water from the other chamber of the tank whereby the volume of water in each chamber may vary but the total volume of water in the tank is substantially constant.

10. A thermal storage tank for holding varying volumes of water at two different temperatures comprising:
peripheral walls and opposed end walls, an impervious flexible membrane having a closed end and open end, the open end having a peripheral edge which is secured about respectively contiguous peripheral walls of the tank intermediate said end walls thereby dividing said tank into two variable volume chambers, each chamber capable of holding water, conduit means for selectively feeding water into and removing water from each chamber, said flexible membrane being in the shape of a bag whereby when water at one temperature is removed from one chamber while a substantially equivalent amount of water at a second temperature is fed into the other chamber, the membrane moves to accommodate the varying volumes of different temperatured water within the tank, the total volume of water in the tank at any time being substantially constant, said flexible membrane preventing blending of the two different temperatured water within respective chambers and being substantially water weight.

11. In a system for conditioning a load to a first predetermined temperature wherein said load is in a piping circuit, including pump means for pumping water about said circuit, heat transfer means for conditioning water in said circuit prior to said load to a second predetermined temperature in order to condition said load to said first predetermined temperature, the improvement comprising thermal storage tank means including means for separating said thermal storage tank means into variable volume chambers, said chambers including a first chamber capable of storing water substantially at a third predetermined temperature and a second chamber capable of storing water at a fourth temperature; means for selectively withdrawing water at said third temperature from said first chamber and transferring its thermal energy to water in said circuit in order to maintain said second predetermined water temperature; means for permitting a substantially equivalent amount of water as withdrawn from said first chamber to flow into said second chamber and be retained therein at said fourth temperature; said means for separating said thermal storage tank means into said first and second variable volume chambers preventing blending of water at said substantially third predetermined temperature with water at said fourth temperature, the volume of said first and second chambers varying respectively in response to water withdrawn therefrom and flowing thereinto; and means for selectively regenerating said first chamber with water at said substantially third predetermined temperature so that said thermal storage means may contain substantially all water at said substantially third predetermined temperature.

12. The system as defined in Claim 11 wherein said withdrawn water is introduced directly into said circuit and said third temperature is substantially said second temperature and said fourth temperature is substantially the temperature of return ater in said circuit after said load, said circuit being closed whereby said equivalent amount of water flowing into said second chamber is return water.

13. The system as defined in Claim 12 wherein said thermal storage means is a rectangular tank and said separating anti-blending means comprise a vertically floatable baffle, said baffle being substantially the width of said tank and floating upright in water in said tank with a portion thereof above the level of the water and the bottom of said baffle just above the bottom of said tank, means for guiding said baffle for movement from end to end of said tank in response to the volume of water on either side thereof.

14. The system as defined in Claim 13 including two additional like floatable baffles, a centre one of said baffles remaining substantially stationary and separating said tank into a hot water storage tank section and a chilled water storage tank section, the other two baffles providing respective separating and anti-blending means for said hot water storage tank section and said chilled water section, piping and valve means associated with portions of said tank whereby said centre one of said baffles may be selectively moved and the tank converted entirely to a heat-ing or cooling mode or to any combination thereof.

15. The system as defined in Claim 11 or Claim 12 wherein said storage tank means includes peripheral walls, said separating and anti-blending means comprising a flexible impervious membrane having peripheral edges secured to certain of said peri-pheral walls to divide said tank means into said variable volume chambers.

16. The system as defined in Claim 11 or Claim 12 wherein said storage means is closed and includes peripheral walls and opposed end walls, said separating and anti-blending means comprising a flexible impervious membrane, said membrane being in the form of a bag having a closed and an open end, said closed end capable of taking the shape of either end wall and the open end being secured about the peripheral walls intermediate said end walls.

17. The system as defined in Claim 12 wherein water pressure in said circuit including said load is at a first pressure and water in said thermal storage means is at a second pressure substantially lower than said first pressure; said means for selec-tively withdrawing water from said first chamber and introducing it into said circuit including further pump means; said means for permitting a substantially equivalent amount of return water to flow into said second chamber from said circuit including turbine means, a motor means operatively associated with said further pump means; said turbine being operatively associated to said motor means whereby energy required to pump water from said second pressure to said first pressure is conserved through flow of return water in said turbine means.

18. The system of Claim 11 or Claim 12 wherein said thermal storage means includes a plurality of separate storage tanks each having an impervious flexible membrane defining respec-tive variable volume chambers, and means including piping and valve means to permit any combination of said thermal storage tanks to be included into a selected mode of operation for selectively withdrawing water from and permitting flow of water into respective chambers of said plurality of tanks.

19. In an air conditioning system for a building, said system including heat pump means including evaporator means, clean condenser means and tower condenser means; a chilled water circuit including said evaporator means, chilled water pump means and a plurality of heat exchange means for selectively cooling areas of said building to a predetermined temperature; a heating water circuit including said clean condense. means, heating water pump means, and heat exchange means for selectively heating areas of said (claim 19 cont'd) building to a predetermined temperature, auxiliary heating means for selectively adding heat to said heating water circuit and said clean condenser adapted to reclaim heat in the building from said evaporator for said heating water circuit; a water tower circuit including said tower condenser means and tower circuit pump means, said water tower circuit being selectively operable to remove unwanted heat from the building as a result of cooling areas of said building; the improvement comprising thermal storage means including at least two storage tanks, each tank having means for separating the tank into first and second variable volume chambers and preventing blending of different temperatured water between the respective two chambers; cool storage piping circuit means for selectively transferring stored thermal energy in at least one of said storage tanks to water in said chilled water circuit and hot storage piping circuit means for selectively transferring stored thermal energy in at least one of said storage tanks to water in said heating water circuit as demand for cooling and heating of the building requires in order to supplement the thermal energy of water in the chilled water and heating water circuits with thermal energy from said storage tanks and thereby meet the respective cooling and heating demand in the building at the particular time; said separating and anti-blending means comprising impervious flexible membranes attached about certain peripheral walls of respective tanks to divide the respective tanks into said two varying volume chambers and each said piping circuit means including means for withdrawing water from one of said chambers in at least one of said tanks while a substantially equivalent amount of water is returned to the other chamber of said at least one of said tanks.

20. The air conditioning system of Claim 19 wherein water pressures in each said heating and chilled water circuits including said respective heating and cooling loads are relatively high whereas water in said thermal storage means is at a relatively low pressure; said means for selectively trans-ferring thermal energy from cold water storage tanks to water in said chilled water circuit including means for withdrawing water from at least one first chamber of said cold storage tanks and directly introducing such withdrawn water into said chilled water circuit and including further chilled water pump means and means for permitting an equivalent amount of return chilled water to flow into at least one second chamber of said cold storage tanks including chilled water turbine means; motor means operatively associated to driving of said further chilled water pump means, said chilled water turbine means being operatively connected to said motor means whereby energy required to pump water from said low pressure chilled water storage tanks into said high pressure chilled water circuit is conserved through flow of return water in said chilled water turbine means; said means for selectively transferring thermal energy from hot water storage tanks to the water in said heating water circuit including means for withdrawing water from at least one first chamber of said hot storage tanks and directly introducing such withdrawn water into said heating water circuit and including further heating water pump means, and means for permitting an equivalent amount of hot return water to flow into at least one second chamber of said hot storage tank including heating water turbine means; additional motor means operatively associated to driving said further heating water pump means, said heating water turbine means being operatively connected to said additional motor means whereby energy required to pump water from said low pressure heating water storage tanks into said high pressure heating water circuit is conserved through flow of return water in said heating water turbine means.

21. A method of continuously preventing blending of two varying volumes of water at different temperatures in a thermal storage system wherein said system includes a storage tank having peripheral walls and opposed end walls and means for simultaneously feeding water at one temperature and withdrawing water at another temperature from the respective ends of said tank, comprising: providing an impervious flexible membrane in the shape of a bag having a closed end and an open end, and securing said open end about the peripheral walls of said tank whereby said membrane continuously separates said tanks into two variable volume chambers containing said varying volumes of water while the overall volume of said tank remains the same.

22. The method of Claim 21 wherein the flexible membrane is substantially water weight.

23. The method of Claim 21 wherein the flexible membrane substantially takes the shape of a part of said tank when there is substantially no water in one chamber compared to the other chamber.

24. The method of Claim 21 wherein the tank is made of concrete and anchor means are secured to the peripheral walls of said tank, said anchor means having an inwardly directed enlarged portion, and further characterized by said open end of said mem-brane having a bifurcated peripheral edge having end portions, which end portions are secured around said enlarged means.

25. A system for conditioning a load to a predetermined temperature wherein said load is in a water piping circuit, includ-ing: pump means for pumping water about said circuit; heat transfer means for conditioning water in said circuit prior to said load to a second predetermined temperature in order to condition said load to said first predetermined temperature; thermal storage means in-cluding means for separating said thermal storage means into vari-able volume chambers, said chambers including a first chamber capable of storing water substantially at a third predetermined temperature and a second chamber capable of storing water at a fourth temperature; means for selectively withdrawing water at said third temperature from said first chamber and introducing it into said circuit in order to maintain said second predetermined water temperature; means for permitting a substantially equivalent amount of water to flow into said second chamber and be retained therein at said fourth temperature; said means for separating said thermal storage means into said first and second variable volume chambers preventing blending of water at said substantially third predeter-mined temperature with water at said fourth temperature and varying the volume of said first and second chambers in response to water withdrawn therefrom and flowing thereinto; said thermal storage means including peripheral walls and said separating and anti-blending means comprising a flexible impervious membrane having peripheral edges secured to certain of said peripheral walls to divide said tank means into said variable volume chambers, and means for feeding and withdrawing water from said chambers whereby the volumes of different temperature water in each chamber may (claim 25 cont'd) vary but the total volume of water in the tank means is substan-tially constant; and means for selectively regenerating said first chamber with water at said substantially third predetermined tem-perature so that said thermal storage means may contain substantial-ly all water at said substantially third predetermined temperature.