HEAT EXCHANGE SYSTEM WITH COMPENSATION OF DIMENSION CHANGE OF HEAT STORAGE MATERIAL AND METHOD FOR EXCHANGING HEAT BY USING THE HEAT EXCHANGE SYSTEM

Abstract

A heat exchange system with at least one heat exchange chamber with heat exchange chamber boundaries which surround at least one heat exchange chamber interior of the heat exchange chamber is provided. The heat exchange chamber boundaries include at least one first opening for guiding in an inflow of at least one heat transfer fluid into the heat exchange chamber interior and at least one second opening for guiding out an outflow of the heat transfer fluid out of the heat exchange chamber interior. At least one heat storage material is arranged in the heat exchange chamber interior such that a heat exchange flow of the heat transfer fluid through the heat exchange chamber interior causes a heat exchange between the heat storage material and the heat transfer fluid.

Claims

1. A heat exchange system, with at least one heat exchange chamber with heat exchange chamber boundaries which surround at least one heat exchange chamber interior of the heat exchange chamber, wherein the heat exchange chamber boundaries comprise at least one first opening for guiding in an inflow of at least one heat transfer fluid into the heat exchange chamber interior and at least one second opening for guiding out an outflow of the heat transfer fluid out of the heat exchange chamber interior; at least one heat storage material is arranged in the heat exchange chamber interior such that a heat exchange flow of the heat transfer fluid through the heat exchange chamber interior causes a heat exchange between the heat storage material and the heat transfer fluid; and wherein the heat exchange chamber comprises at least one packing device for compensation of a packing of the heat storage material within the heat exchange chamber interior.

2. The heat exchange system according to claim 1, wherein at least one of the heat exchange chamber boundaries comprises the packing device.

3. The heat exchange system according to claim 2, wherein the heat exchange chamber boundary with the packing device is a ceiling of the heat exchange chamber and/or a side heat exchange chamber boundary of the heat exchange chamber.

4. The heat exchange system according to claim 3, wherein the ceiling is a vertically sliding ceiling of the heat exchange chamber.

5. The heat exchange system according to claim 3, wherein the side wall of the chamber comprises at least one sheet pile wall.

6. The heat exchange system according to claim 1, wherein the packing device comprises at least one flexible flow obstacle for the heat exchange flow.

7. The heat exchanges system according to claim 6, wherein the flexible flow obstacle comprises at least one bag which is filled with air.

8. The heat exchange system according to claim 3, wherein the ceiling is supported by the heat storage material.

9. The heat exchange system according to claim 3, wherein the ceiling and a side heat exchange chamber boundary are connected together and hermetically sealed.

10. The heat exchange system according to claim 1, wherein the packing device is arranged between at least one heat exchange boundary of the heat exchange chamber and the heat storage material.

11. The heat exchange system according to claim 1, wherein the packing device comprises flow flaps.

12. The heat exchange system according to claim 11, wherein the flow flaps are passive flow flaps which are arranged at the ceiling of the heat exchange chamber.

13. The heat exchange system according to claim 1, wherein the heat transfer fluid comprises a gas at ambient gas pressure.

14. The heat exchange system according to claim 1, wherein the heat exchange chamber is at least partly arranged in at least one soil excavation of a soil.

15. The heat exchange system according to claim 14, wherein at least one the heat exchange chamber boundaries is at least partly formed by at least one soil boundary.

16. A method for exchanging heat by using the heat exchange system according to claim 1, wherein in an operating mode of the heat exchange system the heat exchange flow of the heat transfer fluid is guided through the heat exchange chamber interior, wherein a heat exchange between the heat storage material and the heat transfer fluid is caused.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Further features and advantages of the invention are produced from the description of exemplary embodiments with reference to the drawings. The drawings are schematic.

[0066] FIG. 1 shows a heat exchange chamber of the heat exchange system.

[0067] FIG. 2 shows a temperature distribution of the heat exchange chamber of FIG. 1 in a charging mode.

[0068] FIG. 3 shows the heat exchange system in a charging mode.

[0069] FIG. 4 shows the heat exchanges system in a discharging mode.

[0070] FIG. 5 shows a heat exchange chamber with an uncontrolled flow.

[0071] FIGS. 6 and 7 show solutions for the avoidance of the uncontrolled flow of heat transfer fluid depicted in FIG. 5.

[0072] FIGS. 8 to 11 show alternative embodiments of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0073] Core of this invention is a heat exchange system 1 with a heat exchange chamber 11 on a high temperature level.

[0074] Heat storage material 121 (e.g. stones or sand) which is located in the heat exchange chamber interior 112 of the heat exchange chamber 11 can be charged and discharged with heat via the heat transfer fluid 13. Heat is stored by the heat storage material 121 and can be release from the storage material.

[0075] The temperature level of the stored heat is significantly higher compared to methods applied so far to increase the efficiency. The temperature level lies between 300 C. and 1000 C., preferably between 500 C. and 1000 C., more preferably between 650 C. and 1000 C. and most preferably between 700 C. and 1000 C. The thermal capacity of the heat exchange system 1 lies in the range between 0.3 GWh and 100 GWh which causes a thermal power of 50 MW.

[0076] The heat exchange system 1 comprises at least one heat exchange chamber 11 with heat exchange chamber boundaries 111 which surround at least one heat exchange chamber interior 112 of the heat exchange chamber 11. The heat exchange chamber 11 is a horizontal heat exchange chamber 113.

[0077] The heat exchange chamber boundaries 111 comprise at least one first opening 1111 for guiding in an inflow 132 of at least one heat transfer fluid 131 into the heat exchange chamber interior 112 and at least one second opening 1112 for guiding an outflow 133 of the heat transfer fluid 131 out of the heat exchange chamber interior 112. At least one heat storage material 121 is arranged in the heat exchange chamber interior 112 such that a heat exchange flow 13 of the heat transfer fluid 131 through the heat exchange chamber interior 112 causes a heat exchange between the heat storage material 121 and the heat transfer fluid 131.

[0078] Additionally, the heat exchange chamber 11 comprises at least one packing device 123 for compensation of a packing of the heat storage material 131 within the heat exchange chamber interior 112.

[0079] Exemplarily, the heat exchange chamber length of the horizontal heat exchange chamber 11 is about 200 m, the heat exchange chamber height of the heat exchange chamber 11 is about 10 m and the heat exchange chamber width of the heat exchange chamber is about 50 m.

[0080] With the aid of the proposed heat exchange system 1, thermal energy can be stored on a high temperature level during the charging mode. This stored thermal energy can be used during the discharging mode for the production of steam in a water steam cycle for reconversion into electrical energy.

[0081] There is a transition area 116 of the heat exchange chamber 11 with a tapering profile 1161. Thereby an opening diameter 1113 of the opening 1111 or 1112 aligns to a first tapering profile diameter 1162 of the tapering profile 1161 and a chamber diameter 117 of the heat exchange chamber 11 aligns to a second tapering profile diameter 1163 of the tapering profile 1161.

[0082] The inflow 132 of the heat transfer fluid 13 is guided into the heat exchange chamber interior 112. The guided inflow 132 is distributed to a wide area of heat storage material 121. By this measure a capacity of the heat exchange unit (heat storage material 121 which is located in the heat exchange chamber interior 112) can be utilized in an advantageous manner.

[0083] The transition area 116 is short. The short transition area 116 projects into the heat exchange chamber 11. The result is a short transition channel for the guiding of the inflow 132 into the heat exchange chamber interior 112 of the heat exchange chamber 11.

[0084] The heat exchange system 1 is additionally equipped with at least one flow adjusting element 134 for adjusting a mass flow of the heat exchange flow 13 of the heat transfer fluid 131 through the heat exchange chamber interior 11. The flow adjusting element 134 is an active fluid motion device 1341 like a blower or a pump. Such a device enables a transportation of the heat transfer fluid 131 through the heat exchange chamber interior 112 of the heat exchange chamber 11. The blower or the pump can be installed upstream or downstream of to the heat exchange chamber 11.

[0085] In the charging mode, the heat transfer fluid 131 enters the heat exchange chamber 11 through a diffuser 1164. The diffuser 1164 comprises stones 1165 and is arranged at the transition area 116 of the heat exchange chamber 11.

[0086] The heat exchange flow 13 of the heat transfer fluid 131 is directed in the charging mode direction 135. The flow adjusting element 134, 1341 is advantageous installed upstream of the charging unit 200, 201 (FIG. 3): Relatively cold heat transfer fluid passes the flow adjusting element 134, 1341 before absorbing heat from the charging unit.

[0087] For the charging mode, the heat transfer fluid 131 is heated up from ambient conditions by the electrical heating device 201 (charging unit 200). This charged (heated) heat transfer fluid is guided into the heat exchange chamber interior 112 of the heat exchange chamber 11 for charging of the heat storage material. Thereby the heat exchange between the heat transfer fluid and the heat storage material takes place. With reference 2000 the temperature front at a certain time of this charging process is shown (FIG. 2). In addition, the temperature gradient 2001 which results in the temperature front is depicted.

[0088] For the discharging mode the heat exchange system 1 comprises one or several heat exchange chambers 11 mentioned above, an active fluid motion device 1341 to circulate the heat transfer fluid 131 and a thermal machine for re-electrification, which can be a water/steam cycle 1003. The working fluid of this cycle is water and steam. The water/steam cycle 1003 has the function of a discharging unit 400. Essential components of the steam turbine cycle 1003 are a steam turbine 1006 and a generator 1004.

[0089] In the discharging mode, the heat exchange flow of the heat transfer fluid is directed into the charging mode direction 136.

[0090] With the aid of the heat exchange system (heat exchanger) 1002 heat of the heat transfer fluid is transferred to the working fluid of the steam cycle 1003.

[0091] The heat exchange system 1 comprises a closed loop 1005. Heat exchange fluid which has passed the heat exchange chamber interior 112 is guided back into the heat exchange chamber interior 112.

[0092] FIG. 5 shows the problem of packing of the heat storage material. An additional path on the ceiling of the heat exchange chamber for flow of heat transfer fluid is available. The control of heat exchange flow through the heat exchange chamber interior is crucial. Based on the invention the gap is reduced.

[0093] Concerning a first embodiment, the ceiling of the heat exchange chamber is just laid on the heat storage material. Due to gravity force (or vacuum in the heat exchange chamber interior by sucking of gaseous heat transfer fluid), the ceiling is pressed to the heat storage material (FIG. 6). With the installation of guidance system (e.g. rail guidance) or rim structures (e.g. notches, indentations, grooves) along the borders of the ceiling and supporting structure an even lowering (vertical movement) of the ceiling is ensured. The lowering of the ceiling and the sealing of the gap occurs due to the ceilings net weight. Furthermore the guidance of the ceiling and the connections to the walls are designed such that no leakage occurs in the heat storage unit. Additionally it is possible to cover the entire storage with a foil to ensure leakage tightness. This foil is glued to the outer storage containment and can be made of EPDM foil.

[0094] In an alternative embodiment, flow flaps are used to compensate the packing of the heat storage material. To close the gap passive flow flaps are installed over the whole heat exchange chamber storage length. These flow flaps are mounted with a flexible bearing, as shown in FIG. 7. When the filling height of the storage decreases, because of the higher density of the storage filling material, the flow flaps close the gap between the ceiling and the actual filling height continuously due to their net weight.

[0095] It is also possible to build the ceiling, also as firmly connected support structure, to close the gap passive flow flaps are installed over the whole storage length. These flow flaps are mounted with a flexible bearing, as shown in FIG. 7. When the filling height of the heat storage material decreases, because of the higher overall density of the heat storage material, the flow flaps close the gap between the ceiling of the heat exchange chamber and the actually filling height continuously due to their net weight.

[0096] The embodiment concerning FIG. 8 the flexible flow obstacle 1232) comprises an air bag. To prevent bypass flows and resulting heat losses, one or more air bags can be installed between the supporting structure of the heat storage and the lowering, insulated ceiling.

[0097] The number and the size of installed air bags depend on the permeability of the insulation above the storage material towards the heat transfer fluid. The air bags block the heat transfer fluid, so that it has to flow through the storage material to reach the second opening. The air bag has to be made out of a flexible, elastic material which adapts to the form of the gap. It also needs to be temperature resistant to the temperatures occurring above the insulated ceiling. The volume of the air bag has to adapt to the volume of the gap (especially height and width if the length of the air bag is parallel to the flow direction of the heat transfer fluid) at all times during operation. This can be solved by pumping a fluid (e.g. air) into the air bag when the storage is cooled down (discharging) and by pumping a fluid out of the air bag when the storage is heated up (charging) in a way that the pressure in the air bag is kept at a constant level.

[0098] Alternatively, a number of air bags is possible, too (see FIG. 9).

[0099] Another option to increase the flow resistance between the insulated ceiling (118) and the supporting structure of the heat storage material is to install flexible flow obstacles which cover the entire cross section of the growing gap (see FIG. 10. These flow obstacles are connected to both the supporting structure above and the insulated ceiling underneath which lies on top of the storage material. The flow obstacles do not absorb any forces resulting from the lowering of the insulated ceiling so that the insulated ceiling is always in direct contact with the storage material due to gravity and/or the low pressure inside the void volume of the storage material. The flow obstacles can be made out of temperature resistant fabrics with a high flow resistance and they can be folded before the first operation of the heat storage starts as indicated in FIG. 5. As the insulated ceiling lowers during operation of the heat storage, the folded fabrics will step by step unfold and therefore they will cover the cross section of the gap entirely at all times. There can be a guiding system at the side of the heat storage which connects the flow obstacles to the inner wall to reduce leakage at the sides of the flow obstacles (see FIG. 11).

[0100] A further embodiment results by at least partly digging of the heat exchange chamber: In order to reduce the installation cost of the heat exchange chamber and in order to create a volume adapting containment (heat exchange chamber with the packing device) the heat exchange chamber is at least partly located in an excavation.

[0101] The heat storage material comprises stone. Loads of the heat exchange chamber, e.g. due to thermal expansion and gravity forces, will be supported by the surrounding soil and a flexible ceiling.

[0102] The boundaries of the heat exchange chamber and the base of the heat exchange chamber can be made out of concrete, steel, porous concrete, foamed clay or any other building material which is able to separate the surrounding soil from the storage material inside. Especially for a cold end of the heat exchange chamber, sheet pile walls can be a cheap and simple way to build an airtight boundary between storage material and soil.

[0103] Locks of the sheet pile wall are be welded so that the sheet pile wall is airtight. The sheet pile wall and the base of the heat exchange chamber form a fixed and defined shape so that the heat transfer fluid can be distributed and flow optimally through the heat exchange chamber interior with the stones.

[0104] Because the heat storage material is strictly separated from the surrounding soil, the heat exchange chamber with the heat storage material is more independent from a quality of the surrounding soil. Therefore, the number of possible locations to install the heat exchange chamber of the heat exchange system increases.

[0105] A fixed shape of the heat exchange chamber prevents the excavation from flattening due to thermal expansion and shrinking which would increase heat losses due to declined insulation and increased surface.

[0106] Thermal insulation layers are attached to the heat exchange boundaries (e.g. ceiling, side walls or vase) either on the inside or on the outside to reduce heat losses and to save the surrounding soil from overheating. The insulation material is selected from the group of ceramics, sinter, bricks, foamed clay, mineral wool, mineral foam, mineral fibers, foam glass, vermiculite, perlite, chamotte, formed vacuum components, calcium silicate, and microporous insulation material.

[0107] Instead of a conventional static ceiling with thermal insulation, a flexible layer of thermal insulation covers the heat storage material. Optionally an inner layer to protect the entire thermal insulation layer from abrasion is to be installed.

[0108] In order to prevent the heat transfer fluid from exiting the heat exchange chamber to the sides, an airtight foil is installed. This foil can be installed in between the supporting structure (heat exchange chamber boundaries like heat exchange chamber wall or base of the heat exchange chamber) and the insulation layer.

[0109] Since there is no static ceiling, the airtight foil on top of the heat exchange chamber directly lies on top of the insulation layer. The foil can be tightly connected to the top of the side walls of the heat exchange chamber so that no air gaps will occur. To avoid tearing of the airtight foil, it can be installed with wrinkles so that it can unfold in the case of a thermal expansion of the heat storage material.

[0110] The thermal insulation layer (or the abrasion protection layer) directly lies on top of the heat storage material so that no further supportive structure is needed here. A soil layer is located on top of the thermal insulation layer to cover it.

[0111] The soil on top of the heat exchange chamber is preferably the soil taken from the excavation in order to avoid expensive transportation.

[0112] The thermal insulation layer which lies on top of the heat storage material can be straight or curved depending on its total expansion and/or shrinking due to the temperature changes and the load resulting from the soil on top of it to avoid a formation of air gaps

[0113] The first opening (inlet opening) and the second opening (outlet opening) of the heat exchange chamber are tightly connected to the supporting structure so that no heat transfer fluid can leak. The defined shape of the heat exchange chamber boundaries of the heat exchange chamber prevent the first and the second opening from shifting. This results in an optimal position of the first and second opening throughout the entire lifecycle of the heat exchange chamber so that the heat transfer fluid is distributed ideally.

[0114] Because a part of the piping system which connects to the heat exchange chamber is installed below ground level, expensive and complex pipe support can be avoided. The weight of this part of the piping system is supported by the surrounding soil.