FR2587790A1 - Modular device permitting heat storage from at least two energy sources, one of which is intermittent, and installation using such a device - Google Patents

Abstract

The invention relates to a modular device permitting heat storage from at least two energy sources, one of which is intermittent. This device comprises: - a vertical cold-water inlet nozzle 16 connected to a feed pipe 22; - a hot-water injection nozzle 28 which emerges at the upper part of the tank and whose lower end is connected via a heat-exchange zone 26 to the cold-water feed pipe 22, downstream of the tee connection (tap-off) on this pipe for the cold-water inlet nozzle 16; - means 30 for drawing off hot water, and - a valve 20 capable of being moved automatically between a position, in which it interrupts the supply of cold water to the tank, and a position, in which it re-establishes the supply of cold water whilst preventing the latter from reaching the injection nozzle.

Description

 Modular device allowing thermal storage from at least two energy sources, one of which is intermittent, and installation using such a device.

 In addition to an auxiliary heat source operating with electricity, gas or fuel oil, storage heating systems are more and more commonly used a more economical auxiliary source of energy which is available intermittently, for example. example of solar collectors, a heat pump, a heat recovery system for domestic chimneys, etc.

 However, all of these installations have the disadvantage of being expensive and of requiring major work when it is desired to adapt the auxiliary source to an existing storage installation. Thus, by European patent No. 0 031 153, there is known an installation of this type, but which uses two tanks connected in series, one of which is heated by the heat supplied by solar collectors and the other by a auxiliary electric source mounted inside.

The heat transfer fluid is first preheated in the first tank by solar heat, then is heated to a higher temperature in the second tank by the electrical resistance. It is understood that such an installation with two tanks is practically twice as bulky as conventional installations with one tank.

 It is true that in heat storage installations with two sources in which the auxiliary source is also mounted outside the tank, for example in the case of a boiler heated with gas or with fuel oil, it is possible to use only one tank. The hydraulic circuit of the intermittent source is connected directly in parallel to the hydraulic circuit of the backup source, but this connection involves major plumbing and electrical work. In addition, in these installations, the hot water supplied by the external thermal sources is injected into the bottom of the tank where it cools in contact with the cold layers. Although the tank gradually heats up, the water that is drawn from it is at a temperature much lower than that at which it is injected.

The present invention aims to remedy these drawbacks and for this purpose relates to a modular device which is mounted at the bottom of a tank and which makes it possible to carry out thermal storage from an internal energy source, for example an electrical resistance, and at least any external thermal source, for example solar collectors, a heat pump, a chimney heat recovery unit or the like, said device comprising
- a vertical cold water inlet pipe which opens at the bottom of the tank and which is connected in bypass to a cold water supply pipe,
- a hot water injector consisting of a vertical tube which opens at the upper part of the tank and whose lower end is connected via a heat exchange zone to the cold water supply pipe , downstream of the connection thereon of the cold water inlet pipe, said heat exchange zone being thus traversed both by the cold liquid arriving from the reservoir and by the heat transfer fluid arriving from the source or sources intermittent thermal,
a hot water withdrawal tap connected to the injector downstream of said heat exchange zone, and
- a valve mounted upstream of the connection of the cold water inlet pipe on the supply line and capable of moving automatically between a position where it interrupts the supply of cold water to the tank, position that it occupies as long as one does not draw hot water from the tank, and a position where it restores the arrival of cold water while preventing it from reaching the injector.

 The heat exchange zone may advantageously be constituted by the hydraulic thermovalve operating by natural convection which is the subject of patent application No. 82 21453, filed on December 21, 1982, in the name of the Applicant. In this case, to the upper orifice of the thermovalve is connected the lower end of the injector, to its first lower orifice is connected the supply line, downstream of the tap on it of the inlet manifold cold water, and finally to its second lower orifice and to its lateral orifice are respectively connected the hot and cold pipes of the hydraulic circuit (s) of said external heat source (s).

 In order to minimize the thermal losses of the installation, each of said hydraulic circuits corresponding to the various external thermal sources can be fitted on its hot tubing with a device sensitive to heat and which is capable of switching off the thermal source. corresponding when the temperature thereof becomes lower by a predetermined value than the temperature of the upper layer of water in the reservoir. This heat-sensitive device may consist of the thermostatic element which is the subject of patent application No. 84 05798 filed on April 12, 1984 in the name of the Applicant.

 All the constituent elements of the modular device according to the invention are grouped together inside a compact box forming a kit which can be fixed under any storage tank. It suffices to hydraulically connect said housing, to the cold water inlet pipe, to the injector and to the hydraulic circuits - of external thermal sources, to obtain a "multi-energy storage installation, that is to say which can be powered by at least one of several external heat sources and by a backup source, for example an electrical resistance, or a gas or oil boiler.

 The case has on its upper wall two end pieces intended to be respectively connected to the lower ends of the cold water inlet pipe and of the injector, and on its side walls an end piece for connection to the cold water supply. and as many pairs of nozzles for the connection of hydraulic circuits from external sources.

 The case also contains a single circulator for circulating the heat transfer fluid in said circuits, the thermostatic elements associated with the latter, and, in the case where the auxiliary heat source is electric, also a clock intended to start the latter. at nightfall and the circulator at daybreak.

 The injector allows hot water supplied by the thermal sources outside the upper part of the tank to be introduced. Hot water is thus stacked without being mixed with cold water and is therefore available immediately. The injection can be performed over a previously warmed area.

The thermal gains due to the rapid availability of the energy thus stored and the non-mixing with the cold zone more than compensate for the few losses due to operation at a higher average temperature than in the case where hot water was injected into the part. bottom of the tank.

The thermovalve provides a double regulating effect
First, it provides regulation by thermosyphon effect, depending on whether the external heat source is working or not. This effect is described in detail in the aforementioned patent application. On the other hand, it regulates according to the power of the external thermal source in service.

In fact, whatever the said power, the temperature difference between the temperatures at the upper ends of the injector and of the cold water inlet pipe is constant. The hydraulic diagram of the installation must therefore be drawn so that the set temperature of the water drawn from the tank is equal to the sum of the temperature of the cold supply water and the said temperature difference.

Thanks to this property of the thermovalve, it prevents an already heated area from being destroyed.

The invention will be better understood on reading the description which follows, made with reference to the appended drawings in which
Figure 1 is a schematic vertical sectional view of a storage heating installation from an electric heat source and an intermittent external source
Figure 2 shows an example of the installation of Figure 1
FIG. 3 is a schematic elevation view of a storage heating installation from three intermittent external sources and from an electrical source, and
FIG. 4 is an alternative embodiment of the shuttle valve of FIG. 2.

 With reference to FIG. 1, the hot water tank 10 is intended to store the calories supplied to it, on the one hand by an auxiliary electrical resistance 12, and by an intermittent external thermal source 14, constituted for example by a battery of solar collectors, by a heat pump or a device for recovering the heat from a chimney, etc.

 The reservoir is supplied with cold water by a vertical tube 16 whose upper end opens immediately above the bottom 18 of the reservoir and whose lower end is connected to an outlet channel of a three-way shuttle valve 20, mounted under the tank and the other two channels of which respectively receive a cold water supply pipe 22 and a connecting pipe 24 which is connected by a heat exchange zone 26 to a hot water injector 28. This this consists of a vertical tube opening at the top of the tank.

The injector enters the tank from the bottom
18 and goes up internally along the wall of the tank. On its portion located under the tank, is connected a tap 30 through which the hot water located oa the part ~ -e superleure of the tank can be drawn for use.

 In the heat exchange zone 26, the calories brought in from the external source 14 are transferred to the water circulating in the injector 28, and are transferred by convection by the latter to the upper part of the tank. It can thus be observed that the heat flow from the external source 14 moves in the tank against the direction of the heat flow from the auxiliary electrical source 12 or during a withdrawal of the two sources.

 In a manner known per se, the source circuit comprises the intermittent source 14 proper, a hot pipe 32 through which the heated heat transfer fluid leaves the source, a cold pipe 34 which returns the cooled heat transfer fluid to the source and the zone of heat exchange 26, all these elements being mounted in series with a circulator 36 and a heat-sensitive element 38 intended to isolate the source circuit of the injector, when the source 14 does not supply calories. As specified in the preamble to the description, such a heat-sensitive element behaves like a valve which interrupts the circuit when the temperature of the fluid passing through it becomes lower than a predetermined temperature.

The heat exchange zone 26 is shown
schematically in FIG. 1 by a box into which the reservoir circuit (connection pipe 24 and injector 28) and the external source circuit (hot and cold pipes 32, 34) open.

 In the embodiment of Figure 2, the heat exchange zone consists of a hydraulic thermovalve operating by natural convection. It will be recalled that such a thermovalve comprises a tubular body 44 of vertical axis closed at its two ends. The tubular body has in its upper wall a first orifice 43 into which the lower end of the injector 28 is connected. It also has at the upper part of its side wall a lateral orifice 46 to which the hot pipe 32 which arrives from the source and, substantially at the level of the lower wall, two lateral orifices 48, 50 to which the cold pipe 34 and the connection pipe 24 are respectively connected. The operation of this thermovalve will be explained later.

 It will be noted that in the case where the heat transfer fluid of the external source circuit contains an antifreeze, it is avoided to mix it in the thermovalve 26 with the use water which is potable, by connecting the pipes 32, 34 to a heat exchanger 51 mounted inside the thermovalve.

 FIG. 2 also shows a particular embodiment of the shuttle valve 20. This comprises a cylindrical casing 52, closed at its two ends by walls 54, 56 .. The end wall 54 is pierced with an orifice in which the supply line 22 is connected. The casing is extended on the end saparoi side 56 by a tubular portion 58 coaxial and of smaller diameter than the casing. At the end of this tubular portion 58 are connected the inlet tubing 16 and the connecting pipe 24.

Inside said tubular portion is slidably mounted with sealing a substantially cylindrical drawer 60 having a channel 62 which passes through it axially and which curves at its end close to the wall 56 so as to open radially through an orifice 61 on the wall side of the drawer in the vicinity of said end. The drawer is recalled to the right in FIG. 2 by a helical spring 64 bearing on the wall 56 and on a flange 66 formed at the end of the drawer which is close to the wall 54.

In this position, the orifice 61 is located opposite the solid wall of the tubular portion 58, so that the tubing 16 is isolated from the supply line 22.

 The operation of the installation according to the invention will now be described.

 When the external heat source 14 does not provide heat, the water in the tank 10 gradually cools. As soon as the temperature detected inside the tank (for example by means of a sensor mounted at a predetermined level) drops below a set temperature, which is displayed on a thermostat, the latter controls the switching on of the auxiliary electric source 12 which heats the lower part of the tank.

 - In addition to the temperature sensor and the thermostat, a clock can be provided which controls the switching on of the auxiliary source 12 and its deactivation either autonomously or by receiving pulses emitted by the public electricity distribution service. These impulses are generally emitted at daybreak and at nightfall.

 The external source 14 no longer providing heat, the heat transfer fluid of the source circuit. gradually cools. As soon as its temperature becomes lower than the cut-out temperature of the thermosensitive element 38, the latter switches to its state where it isolates the source circuit of the thermovalve 26. Thus, the cold fluid of the soure circuit no longer arrives at the thermovalve.

 If 11 hot water is not drawn off through line 30, the shuttle valve 20 is in its position illustrated in solid lines in FIG. 2, that is to say in position such that the orifice 61 is closed. The tank 10 is therefore completely isolated from the cold supply water and from that of the external source circuit.

 If energy is supplied by the auxiliary source, this supply is homogeneous and takes place in the tank and not through any piping.

 If hot water is drawn from the tank by opening the valve 30, the resulting vacuum in the connection pipe 24 has the effect of urging the slide valve 60 of the shuttle valve to the left in FIG. 2, in a position for which the orifice 61 comes opposite the tubing 16 at the same time as the drawer closes the connecting pipe 24. It follows that an amount of cold water equal to the amount of hot water drawn, penetrates in the lower part of the tank, via the supply line 22, the channel 62 and the cold water inlet pipe 16. This cold water cannot be communicated to the thermovalve 26 since the supply line connection is closed.

 If now, as a result of the operation of the intermittent source, the temperature thereof becomes higher than that of the reservoir, the hot heat transfer fluid which enters the thermovalve 26 through the orifice 46, rises by convection along the injector 28 and is introduced into the upper part of the reservoir 10.

It cannot in fact go down into the thermovalve since the water which fills the latter is at the temperature of the reservoir, therefore at a temperature lower than that of the source. Thus, the cold water taken from the lower part of the tank, descends through the tube 16, crosses the connecting pipe 24 and the thermovalve in which it enters through the orifice 50 and leaves through the orifice 48, reaches the source where it heats up and returns to the thermovalve via the hot pipe 32, and finally is poured into the upper part of the injector 28. The hot-cold front of the tank gradually descends and the tank heats up.

 It will be noted that the heat collected at the source is immediately available, and is not degraded as was the case for known installations in which the injector 28 led to the bottom of the tank, and / or the heat flow , coming from the intermittent source, had the same direction of propagation as the heat flow, coming from the auxiliary source.

 It will be noted that in the case mentioned above where the heat exchanger 51 is used, the circuit taken by the water from the tank is simpler, since the latter, after entering the thermovalve 26, rises directly towards the injector 28. By the way, it heats up against the walls of the heat exchanger 51.

Here also, the shuttle valve 20 prevents the arrival of cold water from the supply line 22, and therefore the cooling of the water in the tank. On the other hand, when water is drawn off through line 30, the drawer 60 moves as previously towards its position in dashed lines in FIG. 2 to allow a quantity of cold water equal to that which has passed through to the reservoir. been withdrawn.

 An important advantage of the device according to the invention lies in the fact that it can be produced in modular form and be suitable for any hot water storage tank.

 The module is in the form of a parallelepipedic box 70 with a base surface at most equal to that of the bottom 18 of the tank, so that it can be accommodated in the size of the latter. It has on its upper wall two end pieces for the connection of the cold water inlet pipe 16 and the injector 28 and on its side walls of end pieces for the connection of the supply line 22, of the line hot 32 and cold pipe 34 of the source circuit. All the elements of the device are housed inside the box and the installer only has to connect the end pieces with the various pipes.

 FIG. 3 represents a variant of the device of FIG. 2 adapted to the case where the tank receives the heat supplied by one or more external thermal sources, by temple of the solar collectors 14, a chimney heat recovery unit 14 ′ and a heat pump 14 ". The three source circuits each include, in series with the source, a thermostatic element 38, 38 ', 38" respectively, intended to isolate the corresponding source circuit, when the source does not produce heat. The source circuits are connected in parallel between the input of the circulator 36 and the orifice 48 of the thermovalve 26.

 The operation of the device in FIG. 3 is identical to that of the device in FIG. 2, except that the calories can be supplied at the same time by one, two or three external sources.

 The device can also be produced in the form of a module 70 'adaptable to any storage tank, new or existing. Since the internal connections between the various elements of the device are already made in the factory, the user only has to make the connections to the module of the injector 28, of the cold water inlet pipe 16, of the pipe. supply 22, hot and cold pipes 32, 34 of the solar collector circuit, hot and cold pipes 32 ', 34' of the recovery circuit, and hot and cold pipes 32 ", 34" of the heat pump circuit.

 It goes without saying that numerous modifications of detail can be made to the embodiments described.

For example, the injector 28 can be placed entirely outside the tank, but it will have to be thermally insulated or heated, for example by means of a heating resistor, so that the heat losses per liter are at most equal to those of the tank. If this precaution were not taken, the injector liquid would become colder than that of the reservoir, and liquid circulation would be established in the reservoir circuit in the opposite direction to the normal direction, bringing cold water from the lower layers. from the tank to the top, and the tank would cool.

 On the other hand, at the link of the shuttle valve of Figure 2, one can use the valve 20 'acting by gravity, illustrated by Figure 4. This valve comprises a cylindrical housing 52' arranged so that its axis is vertical. At the lower and upper ends of the casing are connected respectively the cold water supply pipe 22 and the inlet pipe 16.

The inlet orifice 72 of the supply line 22 on the lower wall of the casing is shaped as a seat on which a valve 74, for example in the form of a ball, can be applied in leaktight manner. The connecting pipe 24 passes through the wall of the casing and its terminal orifice 75 opens a short distance above the valve 74 and is also shaped as a seat.

 The operation of the valve 20 ′ is substantially similar to that of the valve 20 in FIG. 2 when no hot water is drawn off, the valve 74 rests on its seat 72 under the action of its own weight, interrupting the arrival of cold water. The tank 10 and the thermovalve 26 are then insulated with respect to the supply line 22. On the other hand, if hot water is drawn off, a vacuum is created in the connection pipe 24 which sucks the valve 74 .

The latter is detached from its seat 72 and is applied against the seat 76. The cold water can therefore flow towards the reservoir via the tube 16, but cannot reach the thermovalve 26.

 In the case of factory production, the injector may be provided independently of a hot water draw-off rod and its height will be between half the height and the total height of the tank.

 Finally, the device according to the invention can be used for destocking heat or cold storage, by mounting it above the tank.

Claims (11)

R <VENDXCAmIONS  1.- Modular device which mounts to the lower part of a tank and which makes it possible to carry out thermal storage from an internal energy source, for example an electrical resistance, and at least one thermal source any external device, for example solar collectors, a heat pump, a chimney heat recovery system or the like, said device comprising  - a vertical cold water inlet pipe (16) which opens at the bottom of the tank (10) and which is connected in bypass to a cold water supply pipe (22),  - a hot water injector (28) consisting of a vertical tube which opens at the upper part of the tank and the lower end of which is connected via a heat exchange zone (26) to the pipe cold water supply (22), downstream of the connection thereon to the cold water inlet pipe (16), said heat exchange zone thus being traversed as well by the cold liquid arriving from the tank only by the heat transfer fluid arriving from the intermittent thermal source or sources,  - means for drawing off hot water (30), and  - a valve (20, 20 ') mounted upstream of the connection of the cold water inlet pipe (15) on the supply line (22) and capable of moving automatically between a position where it interrupts the arrival of cold water to the tank, position it occupies as long as hot water is not drawn from the tank, and a position where it restores the arrival of cold water while preventing it from win the injector.  2.- Modular device according to revendIcation 1, characterized in that the heat exchange zone is constituted by a hydraulic thermovalve (26) operating by natural convection, which comprises, in a known manner in SOi, a tubular body (4d) with a vertical axis, having at its upper eatrity an orifice (43) to which the lower e-trerity of the injector (28) is connected, at its lower end two orifices (48, 50) to which the cold pipe are connected respectively (34) of the intermittent external source and a connecting pipe (2a) itself connected to the cold water inlet pipe (16), the thermovalve finally comprising at the upper part of its side wall an orifice (46 ) to which the hot line (32) of the intermittent external source is connected.  3.- modular device according to one of claims 1 and 2, characterized in that in the case where the heat transfer fluid of the intermittent source circuit contains antifreeze, said hot (32) and cold (34) pipes are connected between them inside the thermovalve (26), by a heat exchanger (51) which allows a flow of the heat transfer fluid without mixing with the liquid from the tank.  4.- modular device according to claim 1, characterized in that the valve (20) comprises  - a cylindrical casing (52) at one end of which is connected the cold water supply pipe (22) and at the other end of which is connected a tubular element (58) of smaller diameter and of the same axis as the casing and which is extended by said connection pipe (24), the cold water inlet pipe (16) being connected to the connection point between said tubular element and the connection pipe, and  - a drawer mounted to slide with sealing in said tubular element (58), said drawer being pierced with an axial channel (62) which curves to open radially into a lateral orifice (61) located on the side wall of the drawer in the vicinity of its end close to the connecting pipe, said drawer being able to occupy a first position in which its lateral orifice (61) opens in the cold water inlet pipe (16), thus putting the latter in communication with the pipe supply (22), while its end adjacent to said orifice closes the connecting pipe, and a second position for which said lateral orifice is opposite the solid wall of said tubular element.  5.- modular device according to claim 1, characterized in that the valve (20 ') comprises  - a cylindrical casing (52 ') with a vertical axis, at the lower and upper ends of which are connected respectively the supply pipe (22) and the inlet pipe (15), the connection pipe (2S.) passing through the wall of the casing and having its terminal orifice (75) which opens above the orifice (72) for connecting the supply line to the casing, and  - a valve (74) which is applied, under the action of its own weight, on said connection orifice (72) when hot water is not drawn from the tank (10), thus interrupting the arrival of cold water, and which is applied against the terminal orifice (76) when it is sucked in by the vacuum created in the connecting pipe (24) as a result of drawing off hot water.  6.- Modular device according to one of the preceding claims, characterized in that in the source circuit is mounted in series a thermostatic element (38) sensitive to heat, which is capable of interrupting the circulation of the heat transfer fluid when the temperature of the intermittent source becomes lower than a predetermined temperature.  7.- Modular device according to claim 1, characterized in that said withdrawal means are constituted by a tap (30) connected to the injector downstream of the heat exchange zone.  8.- Modular device according to claim 1, characterized in that the injector (28) enters the reservoir through the bottom wall (18) thereof and rises internally to a height between mid-height of the tank and the vicinity of the upper wall of the tank, a hot water draw-off rod, independent of the injector, being. then planned.  9. An ovular device according to claim 1, characterized in that the injector (28) rises e tieriorly along the wall of the reservoir and opens into the latter through the upper wall of the reservoir, the injector then being thermally insulated or heated on its portion outside the tank.  10.- Modular device according to one of the preceding claims, characterized in that the thermovalve (26), the valve (20, 20 '), the thermostatic element (38), the circulator (36) and the pipes which connect between had ,. these elements are grouped in a modular box (70) intended to be relied on the bottom (18) of the tank, said box also containing sections of tubing which end in external end pieces for the connection of the supply line (22 ), the cold water inlet pipe (16), the injector (28) and the hot <32) and cold (34) pipes of the source circuit.  11.- Modular device according to one of the preceding claims, characterized in that in the case of thermal storage from several intermittent sources (14, 14 ', 14 "), each source circuit comprises a thermostatic element (38, 38 ', 38 ") mounted in series, and is connected in parallel between the inlet of the circulator (35) and the lower orifice (48) of the thermovalve (26).