RU2218675C2 - Transformer-type electric water heater - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: proposed electric water heater is, essentially, three-phase transformer having flat laminated magnetic core whose legs carry primary winding connected to ac supply mains, secondary winding being made in the form of short-circuited hollow chamber. Transformer mechanical design is characterized in that short-circuited chamber is hollow and accommodates magnetic core carrying primary winding. Chamber is provides with two conducting jumpers passed through core openings and welded to chamber walls for producing short-circuited turns. Secondary winding, short-circuiting jumpers, bottom, and cover constitute sealed enclosure filled with impregnating compound. Water is heated both in flow mode and in storage mode due to power set up in secondary winding when it carries current and also due to power set up in primary winding , magnetic core, and short-circuited jumpers. EFFECT: enhanced heat-transfer surface of heating element at minimal consumption of active materials and minimal size. 1 cl, 1 dwg

Description

 The invention relates to electric heaters and is intended for hot water supply of residential buildings, small industrial and agricultural enterprises.

The level of the claimed object is known from a device containing a transformer with a spatial magnetic circuit and a three-phase primary winding, the rods of which are located in one plane at an angle of 120 ^o relative to each other, and a secondary winding made of straight tubes of different diameters, which are located one inside the other and short-circuited at the lower ends of the disks, and are located between the rods of the magnetic circuit, while the whole structure is covered by a sealed enclosure (US Pat. 2153779, H 05 V 6/10, F 24 H 1/10, publ. 27.07.2000).

 The disadvantage of this device is the small surface area of heat transfer, as well as the high density of the heat flux from the surface of the tubes, which limits the power of the device.

 The closest in technical essence to the claimed invention is an induction fluid heater containing a housing, a transformer with a multi-rod ferromagnetic core, a multiphase primary winding connected to the AC mains and a secondary winding which is a heat exchanger located on the rods, located in it. The heat exchanger is made in the form of a hollow chamber with a lower inlet and an upper outlet for the passage of a heated fluid, in which there are through vertical channels with electrically conductive walls, in each of which a transformer core rod is installed with a gap (US Pat. 2074529, N 05 V 6/10, F 24 H 1/22, publ. 02.27.97).

 The disadvantage of this device is the design complexity and unsatisfactory weight and size indicators. Another disadvantage of this heater is that it gives off heat not only to the heated liquid, but also dissipates it into the environment, which leads to a decrease in the efficiency of the device. In addition, this device heats the fluid only in the flow mode due to the power released in the secondary winding, which impairs its versatility. The insufficient heat transfer surface area, as well as the high heat flux density from this surface, are also disadvantages of this electric heater.

 The claimed invention is aimed at improving operational and overall dimensions. The technical result achieved in the process of solving the problem is to increase the heating efficiency.

 The required technical result is achieved by increasing the heat transfer area of the heating element with a minimum consumption of active materials and minimal dimensions.

 This is achieved by performing a secondary winding in the form of a short-circuited, hollow chamber, inside of which an inductor is located (magnetic circuit with a primary winding). The inventive design of the secondary winding increases the heat transfer area of the heating element, makes it more compact, versatile and convenient to use.

 The transformer type electric heater has a flat, lined magnetic core with a three-phase primary winding located on the terminals of the magnetic circuit and a short-circuited secondary winding made in the form of a hollow chamber. To create short-circuited turns, the chamber is equipped with two electrically conductive jumpers welded to the walls of the chamber and used to close the phase currents of the secondary winding. These jumpers pass through the windows of the magnetic circuit. The jumpers are not washed with water, therefore they are made of a thicker sheet than the secondary winding. The chamber is equipped with a bottom and a lid, which together create a sealed enclosure that covers the inductor from water. The bottom and cover are welded to the camera body.

The essential features characterizing the claimed device:
restrictive - a transformer type electric heater containing a flat lined magnetic core, a three-phase primary winding connected to an alternating current network, and a secondary winding that acts as a heat exchanger;
distinctive - the secondary short-circuited winding is made in the form of a short-circuited hollow chamber, which together with the bottom and cover forms a sealed enclosure, inside which there is a magnetic circuit with a primary winding, electrically conductive jumpers are installed between the magnetic core rods, the ends of which are welded to the chamber walls.

 The drawing shows the design of a transformer type electric heater with a flat lined magnetic core, the rods 1 of which are located in the same plane relative to each other and are connected by a yoke 2. On the rods 1 there is a three-phase primary winding 3. The secondary short-circuit winding is made in the form of a hollow chamber 4. Short-circuit jumpers 5, located between the cores of the magnetic circuit, are welded along the seam 6 to the body of the chamber 4. The secondary winding together with the cover 7 and the bottom 8 create an airtight core usnuyu shell, inside which is placed an inductor (magnetic circuit with the primary winding). Arrows 9 show one of the options for the flow of a heated fluid that washes the surface of the device. The internal cavity of the chamber where the inductor is located is filled with an impregnating compound.

 The device operates as follows. When the primary winding is connected to a three-phase network, alternating current flows through it, creating a time-varying magnetic flux of the device’s magnetic system. This magnetic flux induces an electromotive force in the secondary winding, under the influence of which a three-phase alternating current flows in a short-circuited chamber. When current flows in the secondary winding, heat is transferred to the heated fluid.

 Due to the fact that the heat transfer area is significantly increased due to the claimed design of the secondary winding, made in the form of a chamber, the heat transfer surface of the electric heater increases, and therefore, the specific surface power decreases, which leads to a deterioration in the conditions of scale formation during heating of the liquid, and therefore provides a longer service life of an electric heater without maintenance. In addition, due to the fact that the design of the electric heater is tight, it can be completely placed in a heated liquid, that is, it can work both in a flowing mode and in accumulating mode, therefore, all the heat power released in it is completely transferred to the heated liquid, which ensures the maximum coefficient the usefulness of the device.

Claims (1)

A transformer type electric heater containing a flat lined magnetic core with a three-phase primary winding connected to an alternating current network and a secondary winding that acts as a heat exchanger, characterized in that the secondary short-circuited winding is made in the form of a hollow chamber, which together with the bottom and cover forms a sealed enclosure, inside of which there is a magnetic circuit with a primary winding, between the rods of the magnetic circuit there are electrically conductive jumpers, the ends of which Rena to the chamber walls.