FI90724C - electric heater - Google Patents

Description

90724

SÅHKOKIUAS

object of the invention is såhkokiuas which kåsittåå låmpoeristetyn outer sheath ympårdi låmpoå storing mass sisåltåvåå 5 stone space and one or useaxnpia såhkovastuksia adapted stone attempted låmpoå heat storing mass and which såhkokiukaaseen includes the election of the air flow connection induced by the sex of the stone and the heater receiving space of the ballot as a heat transfers an order to the stone space heater receiving space or alternatively, 10 insulating them to heat the charging mass.

Electric heaters often have poor loyal properties. The sauna has to be heated too hot, because at lower temperatures the heat output is not enough. On the other hand, the warm-up time may be too long.

Finnish patent application 875786 discloses an electric heater with a charging mass and a thermally insulated outer sheath, which is a so-called "Ready" sauna stove. In such a heater, a low-power resistor is able to heat the stone space so hot that when the lid belonging to the heater is opened, creating an air flow connection between the stone space and the sauna space, the sauna space can be quickly heated to the sauna room temperature and the sauna heating can begin.

25

Despite its stone mass of 100 kg, such a stove is equipped with high-power resistors, because the low-power resistor mentioned in connection with saunaing is not sufficient to keep the temperature of the stones high enough and the stone mass cannot be further increased.

30 The stove is already quite large. The so-called resistor intended for measuring the rock space. the "roughing resistance" can only be, for example, 300 W when the normal thermostatically controlled resistors of the heater total 6 kW.

35 The standard resistors of a Nåmå' heater require a three-phase power supply with at least 10 amp fuses and often 16 amp fuses. If it were desired to make the stove a traditional stove, similar to a wood-heated, storage stove, the stone space would have to be significantly increased from the current one. It is clear that a quantity of 200-500 kg of stone would be able to store the energy needed for 2 normal saunas, but such a quantity of stone is no longer practical in current electric heaters.

All known types of electric heaters require the aforementioned more than 5 man-kilowatts of power. The electricity consumption of the entire house must be designed according to the high instantaneous power demand of the electric heater. Main fuses, house supply lines and transformers have to be dimensioned to withstand this short-term peak load. Often, electrical switchboards have to be equipped with an alternating system of electric heating, which cuts off some other load from the top when the stove is switched on.

Bathing with an electric heater is timed for most users at the same time of day. There are more than 500,000 electric saunas in Finland. Every 15 nights there are about 100,000 saunas on at the same time. The energy requirement for one sauna is about 8 kWh. In the two-hour period, approximately 800,000 kWh will thus be taken from the municipal network. The power demand due to the load of the electric heaters greatly increases the power output in the evening to an unfavorable level.

20

The above-mentioned shortcomings of the known electric heaters can be deduced from the characteristics of the new heater, which are: - immediately in bath condition 25 - low power requirement good steam properties at low temperatures simple connection to the mains - power consumption takes place mainly at night

- a reasonably sized SO

The object of the present invention is to provide a new type of charging electric heater in which the above-mentioned objects are achieved. The characteristic features of the electric heater according to the invention are set out in claim 1. Typically, the phase-changing mass is a meltable mass, preferably aluminum, which stores the thermal energy required for saunaing in the melting temperature. Phase change heat energy associated with various changes in crystal structures or reversible chemical reaction may also be involved. By means of the invention, a small heater 90724 3 can accommodate a huge thermal energy storage compared to previous charging heaters. The practical content of the charging nozzle is made so large by practical dimensions that the high-power resistor can be completely dispensed with and only a small resistor that is constantly on is left. In contrast to the prior art, a low-power resistor connected to such a heater in one phase is sufficient. Preferably, the aluminum used as a meltable mass is placed in a steel container, the inner surface of which is lined with a non-dissolving material. Such are high-temperature fiber socks, glass tubes or ceramic liners with a temperature of 10. In practice, after the sauna has taken place, the charging of the mass that accumulates in the evening takes place largely at the same time.

Other advantages and embodiments of the invention will become apparent below.

15

The invention will now be described with reference to the accompanying drawings, which show some embodiments of the invention.

Figure 1 shows an electric-20 stove storing heat in a meltable mass.

Figure 2 is a cross-section of point II-II in Figure 1.

Figure 3 shows another arrangement of the placement of the molten mass in the heater.

Figure 1 shows a cross-section of a heater according to the invention with the lid open. It comprises an outer jacket 1 which is substantially insulated throughout. This outer casing includes a lid 2 which can be opened as part of it. The thermally insulated outer casing 1 surrounds the stone space 3 substantially tightly also on the sides and partly on the bottom. In the middle of the space 3 of the stone-30, a cylindrical vessel 5 is placed in a vertical position, inside which there is an inner cylindrical channel 10 with electrical resistances 4. The vessel 5 consists of a space between the cylinders filled with aluminum 6. The stone space 3 around the vessel 5 is filled with with a mass, such as 35 for example, in stove stones 8. Synthetic, for example ceramic stove stones can also be used here.

At the lower end of the air duct 10 there is a valve 9, which can be used to control the flow of air and which can be connected to thermostatic means 4. Above the air flow duct, at the top of the selector, there is a protective plate 13 which prevents the discharged sewage water from entering this duct. The lower part of the heater includes a switch housing for electrical connections and thermostatic switches.

5

In the cross-section of Fig. 2, the structure of the heater consisting of nested cylinders is seen, in which the air flow channel 10 and the resistor 4 contained therein are inside.

10 The aforementioned aluminum or its alloy is quite an ideal material for storing lånuno. The melting temperature of aluminum is high (Qs * 400 kJ / kg). In addition, the specific heat capacity of aluminum is quite high (Cp = 900 J / kgC). The melting point of aluminum is also very advantageous. Depending on the alloy, 550 to 660 ° C. The specific gravity of aluminum 15 is 2.7 kg / l. These good features are utilized in a heater like the one described above. Aluminum is melted with a low-power resistor and is kept molten at a constant temperature. When heating and bathing in a sauna, molten aluminum releases energy as it cools and continues to cool.

20

Part of the thermal energy contained in the aluminum canister is used to raise the basic temperature of the sauna to the desired level. The amount of energy left in the silo is used to maintain the temperature of the stove stones in order to dispose of the desired amount of steam. 25 Due to this efficient storage method, it is possible to build a small stove (10 kWh »36 MJ) that stores a large amount of thermal energy for a single sauna session. The total volume of the masses charging the stove can be 30 for example: a silo filled with aluminum 10 1 = 27 kg aluminum stone space 23 1 * 30 kg stove stones.

The total volume is thus 33 l when it is about 70 l in the above-mentioned known "ready-to-use" heater.

35

Figure 3 shows a modification of the embodiment of Figures 1 and 2. Similarly, the corresponding parts are denoted by the same reference numerals as the outer jacket 1, the stone space 3, the electrical resistor 4 and the aluminum groove 6. The air duct 14 is denoted here by reference numeral 14 in 90724 5. Here several circumferential vessels 12 are used. 4 is again set to this channel. The vessels 12 are formed completely sealed and a small expansion space 5 is left in them, although experiments have shown that possible thermal expansion serums do not cause problems. Instead, it is important to line the inner surface of the steel vessel in a suitable manner to prevent molten aluxin from dissolving in the steel vessel.

10 The total charging capacity of the es inter stove is obtained as follows.

In accordance with the above, a 10 l or 27 kg aluminum container is placed inside the thermally insulated outer jacket among a 30 kg stone mass. In this case, the melting heat energy of aluminum is 3 kWh and its cooling heat energy from 700 * to 200 * is about 3.4 kWh. The cooling of the Kivi-15 mass from 600 * to 200 * (average) gives a thermal energy of about 2.7 kWh and the structures 1 kWh, whereby the total charge heat of the heater is about 10 kWh. In addition, the heater is preferably equipped with a resistor of 1000 W, which heat output is also obtained during the sauna. Thus, about 12 kWh of thermal energy is available in two 20 hours, which is well enough for a regular family sauna. If necessary, the resistor is equipped with overheating protection. This is also the case with thermostatic means with which the vessel 5 or the rock space 3 is kept in a constant temperature state.

25

In a standard 7 m3 sauna, a 6 kW heater is normally used. In such a state, the charging stove according to the invention is able to maintain normal sauna conditions as described above for two hours, even if the stove is loaded with 30 continuous castings. Usually, however, the heater is not loaded so much, so that the heater can provide normal sauna conditions for several hours.

After the sauna, the 1000 w resistor in connection with the heater starts to reheat the recharging mass 3.5 and melt the cooled aluminum mass. It takes 11 to 12 hours to fully charge such a heater from a completely empty space. The power of the resistor can be further reduced. The 500 W heating power would still allow for a daily sauna.

6

In Journal of Engineering for Industry, 8/1975 p. 893-896, "Thermal Energy Storage and Control", Schroder introduces various salts and mixtures thereof. For example, LiF / MgF2 alloys offer some alternatives to aluminum. With these, it is possible to achieve better heat storage capacity than with aluminum.

Claims (10)

90724 7 An electric heater comprising a thermally insulated outer sheath (1) surrounding a rock space 5 (3) containing a heat-storing mass and one or more electrical resistors arranged in the rock space as a heat-storing mass (6, 8) comprising a heat (6,8) means for establishing an air flow connection between the stone space and the heater space to transfer heat from the stone space (3) to the heater space or alternatively to insulate these charging masses (6, 8), characterized in that part of the charging mass (6) is said to be hot by binding and transferring the energy used for sauna to the utilization of the phase change heat. 15 Electric heater according to Claim 1, characterized in that the phase-changing mass (6) is arranged in one or more vessels (5, 12). Electric heater according to Claim 2, characterized in that the at least one vessel (12) consists of a space between two inner tubes and the electric resistor (4) is arranged inside the inner tube. Electric stove according to Claim 2, characterized in that the stove comprises a plurality of cylindrical vessels (12) which are arranged on a circumference and in which an electric resistor (4) is arranged in the middle of these. Electric heater according to Claims 1 to 4, characterized in that the resistance space is formed as part of the air flow channel (10) and is arranged vertically. Electric heater according to Claims 2 to 4, characterized in that the vessel (5, 12) is completely closed and a small expansion space is left in it. 8 Electric heater according to Claims 2 to 4, characterized in that the vessel (5, 12) has an inner lining (11) for preventing the material of the vessel from dissolving in its melting tendon. Electric heater according to Claim 7, characterized in that the inner lining (11) of the vessel comprises one of the following: a fiber sock, a glass tube, a ceramic lining. Electric heater according to Claims 1 to 8, characterized in that the charging mass (6) comprises one or more of the following materials: pure aluminum, aluminum alloy, salt alloy. Electric heater according to claims 1-9, characterized in that the thermally insulated outer jacket (1) comprises an openable lid (2) which, when opened, creates said air flow connection from the stone space (3) to the storage space. II 90724 9