Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
  • F28D20/0056—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using solid heat storage material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H7/00—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release
  • F24H7/002—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release using electrical energy supply
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/14—Thermal energy storage

Definitions

• the invention relates to a heat-storing body of metal.
• the invention is also concerned with a heat storage means comprising a heat storing body one sur ⁇ face of which forms a contact surface with a heat- transfer fluid.
• Heat-storing bodies are used widely in various applications to transfer heat supplied to the body and stored therein to a point where it is needed.
• the heat transfer or transmission fluid is often a liquid, typically water, but is it also possible to use a gas.
• the present invention can be applied when the heat transfer medium is either a liquid or a gas.
• Heat-storing bodies are, of course, made of materials of high heat-storing capacity. In many cases, it is also desirable that the heat-storing capacity of the material per unit volume is high. It is well-known to use soapstone as a heat-storing material as it has a high heat-storing capacity as compared with other stone materials. Ceramic and fire-resistant materials as well as mineral materials, such as ferrosilicate, are used widely in the cores of heat storage means.
• the metal heat-storing body of the invention is charac- terized in that it comprises a core of steel, an alloy of good heat resistance being sprayed on the surface of the steel core.
• the core is made of general structural steel.
• the composition of the alloy used as a coating preferably corresponds substantially to the composition of stainless extra- low carbon austenitic steel.
• the heat storage means of the invention is mainly characterized in that the heat-storing body comprises a core of steel, an alloy of good heat resistance being sprayed on that portion of the core surface which is exposed to oxidizing ambient con ⁇ ditions.
• Preferred embodiments of the heat storage means are disclosed in the attached claims 6 to 10.
• the present invention is based on the idea that the • core of the heat-storing body is made of in ⁇ expensive standard steel having excellent heat- storing properties.
• the steel is protected against oxidation and other chemical reactions by means of an alloy which is sprayed on the surface of the steel.
• a major advantage of the invention is that a compact heat-storing body with a high heat-storing capacity per unit volume can be manufactured at low costs.
• the core is made of general structural steel, it is ensured that the material is readily available in different shapes and dimensions to meet the requirements of each particular application.
• the steel core can be manufactured or assembled by welding, which is particularly advantageous in the production of extremely large cores.
• Figure 1 shows the principal features of a heat storage means
• Figure 2 is a back view of the heat storage means of Figure 1;
• Figure 3 is a sectional view along the line III-III of Figure 1; and Figure 4 shows a cartridge provided in the heat storage means of Figure 1 for heat resistors.
• FIG. 1 shows a heat storage means typically connected to a heat exchanger (not shown) for the recovery of heat.
• the heat storage means comprises a heat-storing body generally indicated with the refer ⁇ ence numeral 1.
• the heat-storing body 1 is formed by placing four substantially rectangular steel bodies 2 to 5 side by side.
• the steel bodies 2 to 5 are of general structural steel, such as Fe 52-c (St 52-3), as this type of steel is low in cost and readily available, in addition to which it is easy to weld.
• a contact surface between the adjacent steel bodies 2 and 3, and 4 and 5, comprises a space for an electric heating resistor 6, 7.
• the heat-storing body 1 is heated by the electric resistors, by means of which the temperature is raised to about 550 to 750 C C, a typical operating temperature being about 600°C.
• the temperature of the body 1 may be clearly above 750°C and below 550°C. Above the latter temperature, unalloyed or carbon steels show a high tendency to scale off.
• Each heating resistor 6 and 7 is fitted in a separate cartridge 8 and 9, respectively, which forms a holder for the resistor.
• the cartridges 8, 9, the structure of which will be described in connection with Figure 4, are in close thermal contact with the steel bodies 2 and 3, and 4 and 5, and the heating resistors 6, 7 are in close thermal contact with the cartridges 8, 9, respective ⁇ ly. In this way, it is ensured that the transfer of heat from the heating resistors 6, 7 to the steel bodies 2 to 5 is efficient.
• the heating resistors 6, 7 are indicated with broken lines within the heat storing body 1.
• a cover 10 is fitted tightly to that surface of the heat storing body 1 which is in con- tact with a heat transfer fluid, in this case water, so that a heat transfer space is formed between the cover and the contact surface.
• the cover 10 is provided with an inlet 11 for water and an outlet 12 for steam.
• As the surface of the heat storing body 1 and the cover 10 is surrounded with air and the sur ⁇ face is heated up to a temperature at which general structural steel is oxidized and scales off, an alloy of good heat resistance is sprayed on the surface of the heat-storing body.
• the cover 10 also has to be coated if it is made of steel scaling off at the operating temperature.
• the cover 10 of the total material consumption of the heat storage means could be made of a material of good heat resistance, in which case it need not be coated.
• a suitable starting material for the coating material is a filament material or a powder having a composition that cor ⁇ responds substantially to that of a 18-8-type stain ⁇ less extra-low carbon austenitic steel.
• a low carbon content has proved to be important for the adhesive properties of the coating.
• the carbon content of an effective mixture is about 0.03%. Not even a carbon content below this has proved disadvantageous.
• This kind of steel is readily available and its price is fairly reasonable as compared with many other types of stainless steel or superalloys.
• a Kanthal alloy coating is used in place of stainless steel. The walls surrounded by the heat transfer space are left uncoated as the heat transfer space is free from oxygen.
• FIG. 2 is a back view of the heat storage means, that is, from the side of the cover 10.
• Figure 3 is a sectional view along the line III-III of Figure 1.
• the reference numerals 13 to 15 indicate welds joining the steel bodies 2 to 5. It should be noted in this connection that the steel bodies 2 to 5 are welded together only on the side of the contact surface, that is, the heat-storing body 1 is not welded at the top, at the bottom or in the front, i.e. on the side of the heat ⁇ ing resistors 6, 7. This enables the seams between the steel bodies 2 to 5 to be opened slightly for inserting the cartridges 8, 9 for the heating resistors into close contact with the steel bodies.
• the reference numeral 17' indicates a locking member which is fixed by means of bolts to the steel bodies 2 to 5 to prevent them from being displaced apart from each other.
• FIG. 3 further shows baffle plates 17 to 20 for water positioned one below another in the heat transfer space so as to spread water and steam over the entire contact surface of the heat-storing body 1.
• the baffle plates 17 to 20 are therefore arranged to slant alternately in reverse directions.
• the baffle plates 17 to 20 are preferably attached to the steel bodies 2 to 5 by welding.
• Figure 4 shows the cartridge 8 to be inserted between the steel bodies 2 and 3.
• the cartridge 8 comprises two plate-like parts 21 and 22 so shaped that the heating resistor 6 can be removed from the heat-storing body 1 by withdrawing only the inner part 22.
• the outer part 21 remains in place in the body 1.
• the two-part cartridge 8 is to be preferred in view of maintenance.
• the invention has been described above only by means of its one preferred embodiment. It is to be understood that the details of the invention can be modified in various ways within the scope of the attached claims. Accordingly, it is possible that the heat-storing body is formed by an ingot- or brick- shaped body which is heated e.g. by heat generated in a heat-storing fireplace, the heat-storing body being built inside the fireplace.
• the heat- storing body is not at all heated by electricity, and the heat transfer fluid is not water but air or gas. In place of electricity, the heating can be realized with an oil or gas flame.
• the core need not be made of conventional general structural steel but it is possible to use various low alloy steels and heat refining steels, which are coated; they are, however, more expensive than conventional structural steel so their use is not particularly advisable - especially in view of the object of the invention, that is, the achievement of an inexpensive body having a good heat-storing capacity and resistance to high temperatures.
• the coating may be of some other material suited for high temperatures.
• One suitable alternative might be austenitic-ferritic steel. A criterion for selecting the material is that its heat resistance and adhesive properties are sufficiently good.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Laminated Bodies (AREA)
• Coating By Spraying Or Casting (AREA)
• Central Heating Systems (AREA)
• Other Surface Treatments For Metallic Materials (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8530125

Family Applications (1)

Country Status (6)

Cited By (6)

Families Citing this family (1)

Citations (1)

• 1990
  • 1990-03-26 FI FI901496A patent/FI86474C/fi not_active IP Right Cessation
• 1991
  • 1991-02-21 GB GB9220354A patent/GB2263165B/en not_active Expired - Fee Related
  • 1991-02-21 DE DE4190616A patent/DE4190616C2/de not_active Expired - Fee Related
  • 1991-02-21 DE DE19914190616 patent/DE4190616T/de active Pending
  • 1991-02-21 WO PCT/FI1991/000055 patent/WO1991014906A1/en active Application Filing
  • 1991-02-21 AU AU73036/91A patent/AU7303691A/en not_active Abandoned
• 1992
  • 1992-09-11 SE SE9202623A patent/SE505707C2/sv not_active IP Right Cessation

Patent Citations (1)

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