Search

EP-4323698-B1 - LOW LOSS SENSIBLE HEAT STORAGE

EP4323698B1EP 4323698 B1EP4323698 B1EP 4323698B1EP-4323698-B1

Inventors

  • Van Vliet, Laurens Daniël
  • Mohana, Martin
  • BODIS, PAVOL
  • FISCHER, MICHEL
  • Schansker, Fabian
  • KERSPE, JOBST

Dates

Publication Date
20260506
Application Date
20220419

Claims (17)

  1. Sensible heat storage apparatus (1) comprising - an inner vessel (2) comprising an internal volume (3) adapted to comprise a fluid (4); - an outer container (5) enclosing said inner vessel; - a thermal insulation layer (6) between said inner vessel and said outer container; - at least a first integrated connection (71) and a second integrated connection (72) to connect the internal volume of said inner vessel to an outer environment through the thermal insulation layer; wherein said integrated connections are adapted to each integrate and accommodate at least two individual sub-connections such that every integrated connection forms a single thermal bridge (8) between the inner vessel and outer container and wherein all thermal bridges are located in the bottom 75% of the total height of said outer container; wherein said first integrated connection is adapted to integrate and accommodate a liquid port and at least one further sub-connection; and wherein said second integrated connection is adapted to integrate and accommodate a liquid port and at least one further sub-connection.
  2. Sensible heat storage apparatus according to the previous claim, wherein said internal volume (3) comprises a fluid (4), preferably wherein said internal volume comprises water.
  3. Sensible heat storage apparatus according to any of the previous claims, wherein all thermal bridges (8) are located in the bottom 50%, more preferably in the bottom 25%, most preferably in the bottom 10% of the total height of said outer container (5).
  4. Sensible heat storage apparatus according to any of the previous claims, wherein said inner vessel (2) comprises a stratification device (9), preferably wherein said stratification device comprises one or more perforated plates, preferably two or more perforated plates.
  5. Sensible heat storage apparatus according to any of the previous claims, wherein said further sub-connections are independently selected from the group consisting of liquid ports such as heat coil in- and outlets, liquid inlets and liquid outlets, gas ports such as gas inlets and gas outlets, entry points for an anti-scaling device, entry points for a sensor, such as a temperature sensor, pressure sensor, magnetic field sensor , entry points for an electric heater and electric feedthroughs such as electricity in- and outlets for electrical heaters.
  6. Sensible heat storage apparatus according to the previous claim, wherein said temperature sensor is a multi-point temperature sensor, preferably a thermocouple and/or a resistance temperature detector (RTD) device.
  7. Sensible heat storage apparatus according to the previous claim, wherein said multi-point temperature sensor has at least two measuring points, more preferably at least four measuring points, even more preferably at least five measuring points, most preferably at least six measuring points.
  8. Sensible heat storage apparatus according to any of the previous claims, wherein said thermal insulation layer (6) comprises a vacuum insulation element, preferably wherein said vacuum insulation element has a thermal conductivity in the range of 0.001 W/mK and 0.004 W/mK at a residual gas pressure in the range of 0.1 to 1 mbar and a mean temperature between 50 and 300 °C.
  9. Sensible heat storage apparatus according to any of the previous claims, wherein said thermal insulation layer (6) is locally thicker around one or more thermal bridges and/or wherein the thermal insulation layer is sectionally thickened in essentially the bottom 75%, more preferably the bottom 50%, most preferably the bottom 25% of the total height of the outer container.
  10. Sensible heat storage apparatus according to any of the previous claims, wherein said liquid port and at least one further sub-connection are integrated and accommodated in said first integrated connection (71) via a pipe-in-pipe configuration, preferably a co-axial pipe-in-pipe configuration and/or wherein said liquid port and at least one further sub-connection are integrated and accommodated in said second integrated connection (72) via a pipe-in-pipe configuration, preferably a co-axial pipe-in-pipe configuration.
  11. Sensible heat storage apparatus according to any of the previous claims, wherein said internal volume (3) is between 1 to 15000 liters, preferably between 10 and 1000 liters, more preferably between 50 and 500 liters, most preferably between 75 and 250 liters.
  12. Sensible heat storage apparatus according to any of the previous claims, wherein said inner vessel (2) and/or outer container (5) comprise stainless steel.
  13. Sensible heat storage apparatus according to any of the previous claims, wherein said first integrated connection (71) is adapted to integrate and accommodate a liquid port and a gas port, preferably wherein said gas port and liquid port are integrated in said first integrated connection via a co-axial pipe-in-pipe configuration, preferably wherein said liquid port forms an outer pipe and said gas port forms an inner pipe; and/or wherein said second integrated connection (72) is adapted to integrate and accommodate a liquid port and an entry point for a temperature sensor, preferably wherein said liquid port and entry point for a temperature sensor are integrated in said second integrated connection via a co-axial pipe-in-pipe configuration, preferably wherein said liquid port forms an outer pipe and said entry point for a temperature sensor forms an inner pipe.
  14. Sensible heat storage apparatus according to the previous claim, wherein the length of said gas port integrated and accommodated in said first integrated connection (71) is longer than said liquid port integrated and accommodated in said first integrated connection in said internal volume and/or wherein the length of said first integrated connection is longer in said internal volume (3) than said second integrated connection (72).
  15. Domestic and/or industrial hot water system comprising the sensible heat storage apparatus (1) according to any of the previous claims.
  16. Method for operating the sensible heat storage apparatus (1) according to any of the claims 1-14 for storing heat, said method comprising a storage stage wherein the fluid maintains a storage temperature set by an optional charging stage comprising providing heat to the fluid and/or providing hot fluid, said method further comprising an optional discharging stage wherein hot fluid is obtained from said internal volume (3).
  17. Method according to the previous claim, wherein the storage temperature is between 0 and 200 °C, preferably between 40 and 130 °C, more preferably between 50 and 95 °C.

Description

The invention is in the field of energy storage. The invention is in particular directed to an apparatus for thermal storage and its use in hot water systems. There is a general increase in the use of alternative energy sources such as solar, wind and hydro-powered as society is moving away from fossil-fuel based energy. However, these alternative energy sources generally depend on the amount of available sunlight, wind, water etc. Therefore, the supply of these energy from the alternative sources are typically fluctuating and a misbalance occurs between the supply and demand. A challenge in the field is the prolonged energy storage with a minimal heat loss. This is particularly challenging for sensible heat storage apparatuses. In sensible heat storage, heat is stored in material using the intrinsic heat capacity (Cp) of the material. In contrast to latent heat storage and thermochemical storage, the material in sensible heat storage typically does not undergo a chemical and/or phase change. Sensible heat storage has the advantage over thermochemical heat storage and latent heat storage that it allows for relatively simple systems as no multiphase physics, complex kinetics etc. are involved. One method for storing sensible heat is in the form of hot water tanks. Hot water tank technology may suffer from reduced stored energy as there are typically heat losses over time due to the temperature difference between the environment and the temperature of the internal volume of the tank. Conventional sensible heat storage vessels may suffer from heat losses of 30% to 80% per weak under ideal testing conditions. Long-term storage of heat for multiple days may therefore be challenging. An example to minimize heat losses in a hot water tank is disclosed in US4286573 where a heat trap assembly is disclosed to prevent heat loss in the cold water inlet and hot water outlet piping systems. Another example is disclosed in US9476599 where a hot water storage unit is disclosed comprising a relief device to improve on a pressure temperature relief valve which has been associated with heat loss. A further example of a storage tank is disclosed in CH702484. Herein a thermal stratified storage tank is disclosed with the aim to slow down the flow rate within the tank to an extent that stratification of the liquid medium by purely physical forces and improved utilization of heating energy is possible. Further methods to minimize heat losses include the addition of insulation layers around the vessels. However, there are typically still significant heat losses that reduce the storage time of the energy. Another heat storage tank is described by Thomas Beikircher (Vacuum tank stores heat, BINE-Projectinfo 14/2014), which discloses a vacuum insulated tank that can store heat for a prolonged time. The space between an inner and outer vessel is filled with perlite and placed under vacuum. However, as perlite is a naturally occurring mineral of volcanic origin and typically produces gas over time. This gas may be damaging the vacuum resulting in an increased heat loss. Further, the tank accordingly may require regular maintenance. Other heat storage tanks are described in for instance US6742480 and US2006/201454. Herein, a passage to connect the tank body and outer environment is provided for the inlet and outlet of a fluid. It is desired to provide a sensible heat storage apparatus that does not suffer from one or more of the above-mentioned drawbacks of conventional heat storage apparatus. The present inventors have surprisingly found that minimal heat loss may be achieved by providing a sensible heat storage apparatus that comprises at least a first and a second integrated connection that each form a single thermal bridge. More particularly, the present inventors found that the combination of integrated connections and the location of these integrated connections forming a thermal bridge is particularly beneficial for reducing heat loss. Accordingly, the stored heat may be stored over a prolonged time with minimal heat loss. This may allow for reduced peak loads on the electrical grid, since the misbalance between energy supply and demand can be limited. The stored heat in the sensible heat storage apparatus may for instance be put to use in domestic applications and/or industrial applications for i.a. the provision of hot water. Figure 1 illustrates part of a preferred embodiment of the sensible heat storage apparatus comprising a fluid and one integrated connection.Figure 2 illustrates part of the sensible heat storage apparatus comprising a stratification device.Figure 3 illustrates a preferred embodiment of the sensible heat storage apparatus comprising three integrated connections.Figures 4A-4F illustrate top views of several configurations for the integrated connections.Figure 5 illustrates a preferred embodiment of the sensible heat storage apparatus comprising a stratification device and two integrated connections.Figure 6