RU2094959C1 - Fluid medium electric heater - Google Patents

Abstract

FIELD: off-line heat and hot-water supply systems. SUBSTANCE: inductor 4 is placed inside holding piping 3 in a spaced relation. Inductor 4 is made in built up of composite internal and external permeable cores 5 and 6, respectively, whose walls are joined together at end section on outlet hole side of holding piping 3; inductor coils 7 are placed between them. Walls of internal and external cores 5 and 6 may be also joined on side of inlet holes of piping 3 with bottom of the latter. Central inlet hole of piping 3 is located in center of end section of internal core 5. Clearance between external core 6 and wall of piping 3 is chosen so as to provide utmost heat transfer from inductor case to fluid medium surface and depends on its volume and rate of temperature rise in system. Heating convectors 8 and heating element 9 of hot-water storage tank 10 are connected in parallel with piping 3. Current through inductor coils 7 is controlled by means of temperature controller 15 responding to signals from temperature sensor 16 and from temperature setting unit 17. Power consumption and cold water flowrate are measured by respective meters 14 and 12. EFFECT: improved capacity of electric heater due to at least twice as large inductor case-to-fluid medium contacting surface and reduced magnetic flux built up by inductor coil. 2 cl, 1 dwg

Description

 The invention relates to devices for heating fluids and can be used for heating liquids and gases in heating systems and hot water for residential, industrial and non-industrial premises.

 Known electric heater fluid [1] comprising a housing with a lid and a bottom with holes for supplying and discharging water. In the lower inner part of the housing are electric heating elements. The main disadvantage of electric heaters of this type is the rapid failure of the heating elements during their overheating in the event of scale formation, overvoltage and, as a result, low reliability of the electric heater.

 Known flow electric heater containing a pipe in which an inductor is placed, equipped with an electrically insulated casing and connected to a current source [2] This heater does not provide optimal temperature conditions of the fluid due to the absence of a temperature controller.

 Also known is a fluid electric heater [3] comprising a pipeline, an inductor in an insulating casing located on the pipeline, a current source, power and control units.

 This device does not provide the necessary performance for hot water supply and the required temperature conditions in heating systems due to the fact that a significant part of the magnetic flux generated by the inductor is closed through the air and in the material of the insulating casing and is not used to heat the fluid. This electric heater is adopted as a prototype.

 An object of the invention is to increase the productivity of an electric heater. The technical result is achieved in that the fluid electric heater, like the prototype, contains a pipeline, an inductor in the housing and a current source, unlike the prototype, the inductor is installed inside the pipeline with a gap, the inductor housing with the inductor placed in it is made of a magnetically conductive material and is closed surface with a through central hole. Another difference is that in parallel with the pipeline with the inductor placed in it, the heating converters and the heating element of the hot water storage are connected.

 The drawing shows the design and structural diagram of a fluid electric heater.

 The electric heater contains a “direct” 1 and a “return” 2 sections of the pipeline for supplying and discharging fluid, a pipeline-tank 3 (hereinafter referred to as the tank) with an inductor 4 installed inside. The inductor 4 is made in the form of composite internal 5 and external 6 cores, the walls of which are connected between each other in the end section from the side of the outlet of the vessel 3 and between which the windings of the inductor 7 are located. From the side of the inlets of the vessel 3, the walls of the inner 5 and outer 6 cores can be connected to the bottom of the vessel 3, the central input the opening of the vessel 3 is located in the center of the end section of the inner core 5, the peripheral inlet openings are located in the bottom of the vessel around the perimeter between the side walls of the vessel 3 and the outer core 6 of the inductor 4. All the inlet openings of the vessel 3 are interconnected and connected to the “reverse” section 2 the pipeline. The outlet of the container 3 is located in the center of the container cover and is connected to the “straight” section 1 of the pipeline. Between the “direct” 1 and “reverse” 2 sections of the pipeline, heating converters 8 and a hot water heater coil 9 located in the lower part of the hot water storage tank are connected in parallel. The pipeline 11 of the water supply source through the counter 12 of cold water is connected to the inlet of the bottom of the accumulator 10 and to the consumer cold water distributor. The control device of the inductor 4 consists of a power source 13 of industrial frequency connected through an electric energy meter 14 and a temperature controller 15 to the terminals of the inductor 7. A temperature sensor 16 is located at the feedback input of the controller 15, located at the bottom of the “reverse” section of the pipeline 2, a temperature setting unit 17 is connected to the input of the controller 15; the control device contains a computer 18, the information inputs of which are connected to the outputs of the temperature setting unit 17, a temperature sensor rounds 16, an electric energy meter 14 and a cold water meter 12. The control outputs of the calculator 18 are connected to a printing device 19 and an alarm unit 20.

6
где ω круговая частота колебаний магнитного поля, w = 2πf для F 50 Гц ω 314 1/с;
g электропроводность материала корпуса индуктора;
m_a магнитная проницаемость материала корпуса индуктора.When the heater is operating, the current from the power source 13, flowing through the inductor 7, creates eddy currents in the cores 5, 6 of the inductor 4 and the bottom part of the tank 3, from which the fluid in the tank 3 is heated. The thickness of the walls of the cores 5, 6 is determined by the depth the penetration of the magnetic field created by the coil 7 in the magnetically conductive material and is written by the equation [4]

6
where ω is the circular frequency of the oscillations of the magnetic field, w = 2πf for F 50 Hz ω 314 1 / s;
g conductivity of the material of the inductor body;
m _{a the} magnetic permeability of the material of the inductor housing.

 As a result of the flow of the induced current in the cores 5, 6, the layer Δl of the magnetically conductive material of the body of the inductor 4 is heated by directly induced current, hysteresis phenomena in the material, and heat transfer from the winding of the inductor 7 of the inductor 4.

,
где k_1.2 коэффициент пропорциональности, равный отношению периметра сердечника к его длине.The value of power spent on heating the housing of the inductor 4 when penetrating into the magnetically conductive material of an electromagnetic field is determined by the expression
P _em = I $\genfrac{}{}{0ex}{}{\text{2}}{\text{one}}$ R _pov1 + I $\genfrac{}{}{0ex}{}{\text{2}}{\text{2}}$ R _pov2 (2),
where I ₁ , I _{2 the} effective values of the induced current in the cores 5, 6;
R _pov1 , R _pov2 specific surface resistance of the layer μl of magnetic field penetration into the core material 5, 6 [4]

,
where k _{1.2 is the} coefficient of proportionality equal to the ratio of the perimeter of the core to its length.

Power dissipation P _hist hysteresis at a fixed frequency of the magnetic field oscillation is proportional to the product of the power factor and the value of remanence magnetization reversal of the core material and is 1-2: from value P _um.

The thermal power released by the inductance winding 7 of the inductor 4 can be estimated by the expression
P _rpm = I ² R _rpm (4)
where I is the effective current value in the winding 7;
R _ohm inductance of the inductance winding 7.

As a result, the amount of heat generated by the body of the inductor 4, in this case, the cores 5 and 6 is determined by the total power
P = P _em + P _hist + P _rpm (5)
The gap between the body of the inductor 4 and the wall of the pipe-tank 3 is selected from the condition of maximum heat transfer from the body of the inductor of the fluid.

 This creates a temperature difference between the layers of the medium located in the region of the upper and lower openings of the tank 3, which allows the fluid to flow through closed loops formed as follows: “direct” section 1 of the pipeline heating convectors 8 coil 9 “return” section 2 of the pipeline. The temperature sensor 16, mounted directly on the "reverse" section 2 of the pipeline generates a feedback signal. In accordance with the difference between the values of the current and set temperatures from the task unit 17, the controller 15 proportionally regulates the current in the inductor 7 and, consequently, the heating of the fluid in the tank 3. The heat generated by the heated fluid in the heating element 9 , provides heating of water in the drive 10. The counter of cold water 12 measures the amount of cold water consumed by the consumer. The electric energy meter 14 registers the power consumed by the electric heater. The computer 18 reads and stores data on the flow of water and energy consumed for a certain time and provides the necessary data to the printing device 19. In addition, the computer 18 analyzes the rate of rise of the temperature of the fluid and the pipeline and, if the permissible values are exceeded, generates a control signal for the unit alarm 20.

 Since the contact surface of the inductor body with the fluid increases at least twice, the intensity of heating of the fluid increases. Therefore, the proposed design of the electric heater has increased productivity compared to the prototype. In addition, the implementation of part of the pipeline in the form of storage tanks allows you to optimize temperature conditions in heat supply and improve the energy consumption schedule of this type of heaters.

 Literature.

 1. Kvyatkovsky S. F. et al. Household electric heaters. M. Energoatomizdat, 1987, p. 66 70.

 2. USSR author's certificate N 117388, class F 24 H 1/00, 1959.

 3. Patent of the Russian Federation N 2018061, cl. F 24 H 1/20, 9/20, H 05 B 6/06, 1994.

 4. Govorkov V. A. Electric and magnetic fields. M. Energy, 1968, p. 279,282.

Claims (2)

 1. A fluid electric heater containing a pipeline, an inductor in the housing and a current source, characterized in that the inductor is installed inside the pipeline with a gap, the inductor housing with the inductor placed in it is made of a magnetically conductive material and is a closed surface with a through hole.  2. The electric heater according to claim 1, characterized in that the heating converters and the heating element of the hot water storage device are connected in parallel with the pipe with the inductor located therein.