WO2017007374A1

WO2017007374A1 - Fan heater (hot air blower) with electric heating nozzles of a continuous cylindrical shape

Info

Publication number: WO2017007374A1
Application number: PCT/RU2016/000400
Authority: WO
Inventors: Геннадий Яковлевич ВАЙГАНДТ
Original assignee: Геннадий Яковлевич ВАЙГАНДТ
Priority date: 2015-07-08
Filing date: 2016-06-29
Publication date: 2017-01-12

Abstract

The invention relates to power engineering. A fan heater in which control and indication members are arranged on the external casing, and electric heating elements and the fan are arranged in the internal casing. The electric heating elements are in the form of a spiral of resistive wire wound in multiple layers onto the continuous cylindrical nozzle. Furthermore, the electric heating elements are uniformly arranged inside the housing of the heating diffuser and are oriented longitudinally to the air flow, the resistive wire is covered with a dedicated dielectric heat-conductive sheath, and the continuous cylindrical nozzle is covered with a layer of silica fabric. The invention makes it possible to provide a maximum heat yield and the transmission thereof into an external space.

Description

Title of invention

Fan heater (heat gun) with electric heating

through cylindrical nozzles

Technical field

The invention relates to electrical appliances and is intended for directed heating of rooms and drying surfaces with adjustable angle.

State of the art

Heat guns are known in which air that enters an elongated body is driven by a fan through thermal tubular electric heating elements (TEN), which in the standard design are a metal tube, inside of which there is a resistive wire that is directly a heat source. Between the resistive wire and the TEN sheath there is a heat-conducting ceramic packing. TENs are usually made in the form of a spiral or lattice. As the closest analogue, we chose a Ballu fan heater (heat gun) (see http://www.ballu.ru/catalog-ballu/4575.html for heating and drying surfaces and objects in industrial, public and auxiliary rooms. The performance of the well-known fan heater is portable, the operating position is installation on the floor, the operating conditions are supervised operation, and the operation mode is repeated and short-term. The supporting structure of the fan heater consists of external and internal casings made of sheet steel and having a cylindrical shape. A fan and tubular electric heating elements (TEN) are located in the inner casing. The housing of the control unit is located on the outer casing. The outer casing, closed, protected from the ends of the intake and exhaust grilles, is installed with screws to the handle-stand and has the ability to rotate in a vertical plane. The rotation angle is fixed with screws. A fan draws air through the openings of the intake grille. The air flow drawn by the fan into the housing, passing between the loops of the tubular electric heating elements, is heated and fed into the room through the openings of the air outlet grille.

The disadvantages of the known fan heater are that:

1. In these fan heaters, as in others using standard tubular electric heaters (TENs), there are significant heat losses primarily due to the design of the TENs themselves: the resistive wire, which is directly the source of heating, is located inside the metal tube, which is also the case (shell ) a heating element (TENA), and a heat radiator. Between the resistive wire and the shell of the heating element there is a heat-conducting ceramic packing, a significant amount of heat is also spent on heating the mass of which. The use of forced blowing of heating elements with directional air flow, as, for example, is done in classic heat guns, leads to a sharp cooling of the surface of the heating elements, which occurs much faster than the process of compensating for this temperature loss from an internal heat source (resistive wire) due to the relatively high thermal inertia the design of the heating element due to the presence in it of the above heat losses. This creates a certain limitation of the maximum surface temperature of the heater (and, accordingly, the total power of the heat energy removed and given out when the heater is blown by the fan is also limited), which could potentially be significantly higher in the absence of the above heat losses. 2. The low spatial concentration of the fuel centers (spirals and turns of the resistive wire of the heating element) and, as a result, the low accumulation of thermal energy due to the peculiarities of the tubular design of the heating element: usually the geometry of the heating elements made on the basis of the heating elements is either a simple spiral shape or various derivatives - lattices, arcs, frames, etc. These design features of the heating element, in which a resistive wire, which is a heat source, is located inside a metal shell (tube) filled with heat-conducting ceramic insulating material, do not allow windings of heater coils close to each other, and moreover, perform multi-layer winding, which significantly limits the possibilities increasing the surface temperature of the heating element and the accumulation of its thermal energy.

3. The above-described inertia of heat transfer from the source (resistive wire) to the heat-emitting surface of the heating element leads to an increased thermal load on the resistive wire due to its being in the heat-conducting ceramic packing, which at the same time is partially a heat shield for the resistive wire. As a result of this, especially in the absence of forced blowing of the heating element with air flow, premature destruction of the material of the resistive element occurs (burnout of the heating element).

Thus, another significant drawback of heat guns using standard heating elements is the reduction of their service life-operation in applications in calm air.

To increase the total heat output in heat guns using standard heaters, compensation for heat losses is carried out either by increasing the number of heaters or by increasing power of the heating elements themselves, or both. These methods of increasing thermal power lead simultaneously to two negative consequences: an increase in the size and mass of the devices, and a substantial 90 increase in the consumed electric energy and, as a result, additional economic losses for the user.

Disclosure of invention

The technical result of the claimed invention is the achievement of maximum heat removal and heat transfer due to the fact that:

95 1) Electric heaters are used in the form of a tubular spiral consisting of coils of a resistive wire containing at least two layers of coils of a resistive wire, while the resistive wire is provided with its own dielectric heat-conducting sheath, eliminating the need for application

100 any other additional electrical insulation between the turns and layers of the spiral.

2) These tubular-shaped spirals are made on a rigid frame of a through cylindrical shape (electric heating nozzle - ENS), and are located uniformly along the inner perimeter of the inner casing

105 fan heater (heat gun) longitudinally to the direction of air flow. The multi-layered and tight fit of the coils and layers of the resistive wire to each other allows to ensure minimal heat loss and minimum thermal inertia of the electromotive force, thereby significantly increasing the nominal operating temperature of both the inner and outer surfaces of the electromotive force, including when forced blowing of the electromotive force by air, in comparison with the well-known standard heat guns using heating elements of comparable electrical power. The specified technical result is achieved by the fact that 115 fan heater is claimed, the supporting structure of which includes casings - external and internal, made of sheet steel and having a cylindrical shape. On the outer casing are the controls and indicators, and in the inner casing there are electric heating elements and a fan. The electric heating element is made in the form of a 120 resistive wire spiral coated with its own dielectric heat-conducting sheath and wound multilayer with a snug fit of turns and windings to each other through a cylindrical nozzle coated with a layer of silica fabric and made of thin-walled sheet metal with high thermal conductivity. 125 Electric heating elements made in the form of electric heating nozzles (ENS), having the form of through cylinders, are located inside the heater diffuser uniformly along the inner perimeter of the diffuser body and are oriented longitudinally to the air flow.

The resistive wire is coated with an insulating 130 thermally conductive sheath (braid) made using a high-temperature dielectric filament, and the thickness of this sheath is extremely small and is determined only by the thickness of the filament.

For fastening and arrangement of electric heating nozzles of the ENS, a fastening assembly having a cellular structure is used.

135 Brief Description of the Drawings

The invention is illustrated by illustrations.

Figure 1 shows the construction of a fan heater with an ENS in the context, where: 1 - the outer main casing, 2 - the outer adjacent casing, 3 - 140 fan diffuser, 4 - fan, 5 - heater diffusers, 6 - ENS, 7 - mounting assembly, 9 - power indicator, 1 1 - air outlet grille, 12 - air intake grille, 16 - handle.

Figure 2 shows the design of a fan heater with an ENS, a perspective from the front, where: 9 - light bulb, power indicator light, 10 - 145 light bulb for indicating fan operation, 1 1 - air outlet grille, 13 - stand, 14 - stand fastening screw, 16 - handle, 17 - cable.

Fig. 3 shows the design of a fan heater with an ENS, a perspective from the rear, where: 4 - a fan, 8 - a knob for switching the fan and heater modes, 12 - an air intake grille, 13 - a stand, 150 14 - a screw securing the stand, 16 - a handle, 17 - cable.

Figure 4, a longitudinal section, shows a heating element is an electric heating nozzle (ENS) having a through cylindrical shape, where: 18 is a resistive wire, 19 is a dielectric heat-conducting sheath (braid of a resistive wire), 20 is a layer 155 of silica fabric, 21 - through cylindrical nozzle (inner sleeve), 22 - through cylindrical nozzle (outer sleeve), 23 (1, 2) - a high-temperature cylindrical ceramic insulator, consisting of two parts, 24 - contact group, 25 - riveting nut.

Figure 5, a perspective view, shows a heating element 160 electric heating nozzle (ENS) having a through cylindrical shape, where: 21 is a through cylindrical nozzle (inner sleeve), 22 is a through cylindrical nozzle (outer sleeve), 23 is a high temperature cylindrical ceramic insulator, 24 - contact group, 25 - riveting nut, 26 - screw, providing 165 rigid mechanical fixation of the entire insulator assembly.

The implementation of the invention

b The bearing structure of the fan heater (Figure 1-3) consists of cylindrical casings: external and internal. The outer casing consists of two parts - the outer main casing 1 and the outer

170 adjoining casing 2, made of sheet steel and coated with powder-polymer paint. The inner casing consists of a fan diffuser 3 and one or more cylindrical diffusers of heaters 5 with electric heating nozzles (ENS) 6 having the form of hollow through cylinders. Inside fan diffuser 3

175 is located fan 4. To achieve maximum heat removal and heat transfer, the ENS 6 are located evenly along the inner perimeter of the heater diffuser housing using a special mounting assembly 7 having a cellular structure, and are oriented longitudinally to the air flow. End-to-end cylindrical design

180 heaters allows heat removal through the air flow through them from both the inner and outer surfaces of the ENS 6. On the outer adjacent casing 2 there is a switch for the control unit 8 and the power indicator light 9 and fan 10. The outer main casing 1 and the outer adjacent casing 2 closed

185 air outlet 1 1 and air intake 12 grilles, respectively.

The outer main casing is attached to the stand 13 with axial screws 14, which allow you to adjust the angle of the fan heater in a vertical plane with fixation with screws 15, 16 - carrying handles, 17 - cable.

190 FIG. 4-5 show a heating element — an electric heating nozzle (ENS) having a through cylindrical shape. The ENS is made in the form of a spiral by tightly winding a resistive wire 18 with two or more layers on the inner sleeve of the through cylindrical nozzle 21, covered with a layer of silica fabric 20 and

195 made of thin-walled sheet metal with high thermal conductivity, providing maximum heat transfer with spiral coils of the resistive wire into the cavity of the ENS with minimal heat loss. Accordingly, heat transfer from the turns of the spiral of the resistive wire 18 to the outside of the ENS occurs through

200 outer sleeve 22. The inter-turn and inter-winding electrical insulation of the active windings is ensured by coating the resistive wire 18 (active heater) with a special dielectric heat-conducting sheath (braid) 19, made using a high-temperature dielectric thread (instead of powder

205 ceramic packing used in heating elements). This solution eliminates the need for any other additional electrical insulation between the turns and layers of the resistive spiral. The tight fit of each coil to each other and the tight overlap of the layers of the windings of the resistive wire minimize the space between

210 turns and windings, limited by the small thickness of the dielectric filament, thereby minimizing heat loss, improved heat transfer and a significant (several-fold) increase in the relative heat mass of the entire heating element of the ENS. Thus, the greater the number of turns and windings performed on the inner sleeve

215 of the cylindrical nozzle 21, the higher the thermal power of the electromotive force and the lower its specific heat loss (higher coefficient of heat transfer) due to an increase in the effective ratio of the mass of the heater coil directly to the mass of the metal shells (inner and outer sleeves) of the electromotive force ENS)

220 remains in this case almost unchanged. Higher surface temperature of the electromotive force, achieved due to improved heat transfer and low thermal inertia of the design of the electromotive force, can significantly expand the scope of fan heaters (heat guns) using the electromotive force, compared with standard

225 tubular heating elements, up to the use as an alternative to heat guns operating on liquid and gaseous fuels and having a high outlet temperature. The multi-layer and tight fit of the turns and windings of the heater (spiral wire of the resistive wire) of the electromotive force significantly increase the length and

230, respectively, the mass of resistive material (spiral wire of the resistive wire), and thereby several times (compared with standard tubular heaters - heating elements) to reduce the current surface load on the material of the resistive wire, which greatly increases the service life of the electromotive force compared to standard tubular

235 executions (TENami). Reducing the current surface load of the resistive material (resistive wire) allows the through cylindrical ENS to operate stably in both moving and calm air, in contrast to heat guns using heating elements designed in this case for moving air, which

240 fail quickly (burn out) without forced cooling.

High-temperature ceramic insulators 23 are structurally composed of two parts 23 (1) and 23 (2) and are used for: (a) electrical insulation of the leads of the spiral wire of the resistive wire and heat / electrical insulation of the contact group 24; (b) for positioning and fixing

245 of the base of the contact group 24 in the body of the insulator 23 (2) and the mechanical fixation of the entire insulator (assembly) 23 in the ENS case so that the wall of the ENS on which the insulator is mounted remains between the elements of the assembly 23 (1) and 23 tightly pressed to it (2) with screw 26, providing a rigid mechanical fixation of the entire insulator assembly

250 23 (Fig. 4-5).

The device operates as follows. The air flow drawn by the fan 4 into the diffuser 3, passing through the inner and outer surfaces of the through ENS 6, is heated and fed into the room through the cavity of the air outlet grille 1 1. For carrying 255 of the fan heater, handles 16 are used, which are protected from overheating by the heat-insulating ends of the fastening to the device body (Figs. 1-3).

The end-to-end design of the ENS allows heat removal through the air stream passing through them from both the internal and external surfaces (sleeves) of the nozzle.

260 The uniform arrangement of through-hole cylindrical heating nozzles of the ENS inside the perimeter of the cylindrical diffuser (inner casing) of the fan heater (heat gun) and their longitudinal orientation relative to the axis of the device’s body allow achieving complete air blowing by the blower fan as

265 internal and external surfaces (sleeves) of the heating nozzles, thereby ensuring maximum removal of heat and its transfer to the outer space.

The totality of the above design features of the developed heat guns and used in them

270 ENS electric heating nozzles, including the end-to-end design of ENS electric heating nozzles, their optimal cylindrical geometry and uniform longitudinal arrangement inside cylindrical diffusers to minimize heat loss, including due to high density and multi-layer

275 versions of resistive wire windings allow to achieve a significant increase in the temperature of the heated air leaving the air outlet grill compared to standard tubular electric heaters (TENs) with the same consumed electric power (see comparative Tables 1, 3).

280 Moreover, this effect allows you to significantly expand the scope of the ENS compared to standard tubular heating elements, up to the use as an alternative to heat guns, working on liquid and gaseous fuels (see Table 2), as well as in flowing and stationary heaters (thermoses) of liquid-like 285 carriers, etc.

Table 1: Comparison of the main average values of the characteristics and parameters of electric heat guns using hollow heating nozzles and standard heating elements (data on Ballu products are used).

Table 2: Comparison of the main average characteristics and parameters of electric heat guns using through-hole heating nozzles and gas (propane) heaters.

Air flow 820 m ^~ 7 hours 330 m / h

Average difference 210 220-280

(increase) in temperature

between input and output

at 20 ° C

Volume of heating, M ^J 450 450

Table 3: Comparative values of the parameters of electric heating elements, made in the form of through cylindrical nozzles of the ENS, and standard tubular heating elements in moving air.

Claims

Claim

The fan heater, the supporting structure of which includes casings made of sheet steel and having a cylindrical shape - external and internal, 5 controls and indicators are located on the external casing, and electric heating elements and a fan are located in the inner casing, characterized in that the electric heating nozzles (ENS) They are arranged uniformly inside the heater’s diffuser and are oriented longitudinally to the air flow; the EHCs are made in the form of a spiral of a resistive wire coated with a dielectric heat conductive multi-layered sheath and wound on a through cylindrical nozzle coated silica cloth layer and made of a thin metal sheet.

2. The device according to claim 1, characterized in that a fastening assembly having a cellular structure is used for fastening and arranging 15 ENS.

SUBSTITUTE SHEET (RULE 26)