RU2201557C2 - Fan heater - Google Patents

Abstract

FIELD: electric heating. SUBSTANCE: fan heater has housing, screened inlet and outlet, fan, electric heaters with fastening members, control unit, and thermostatic switch; novelty is that fan heater is provided with frames arranged in tandem inside housing of which one frame that mounts fan is disposed near inlet and other one accommodating electric heaters is placed near outlet; electric heaters are made in the form of stack of flat rectangular ceramic plates arranged in parallel one on top of other, each plate being coated on one side with composite ceramic resistive layer incorporating insulating and conducting phases; extreme sides of each plate are electrically connected in parallel; fastening members of electric heaters are made in the form of flexible clamps secured on two contacts connected through insulators to frame supports near outlet; each plate has width-to-length ratio ranging within

, where L is plate length and B is its width, pitch-to-width ratio, within

, where t is plate pitch, and plate to-resistive layer thickness ratio, within Δ, where δ is plate thickness and

is resistive layer thickness; ratio of frame-to-frame distance l to equivalent diameter of housing d is chosen within

Description

 The invention relates to the field of electric heating technology, specifically to fan heaters, and can be used for heating residential and industrial premises, garages, summer cottages, greenhouses, greenhouses, as well as for drying materials.

 Known fan heater, comprising a housing with inlet and outlet nozzles mounted on supporting devices inside the housing spiral heating elements and a fan, means for monitoring and controlling the operation of the fan and heating elements [1].

 The main disadvantages of the known fan heater are, firstly, in the insufficient reliability of operation, since in the event of failure of any of the sections of the spiral heating element, the fan heater completely loses its working capacity, and secondly, in the noise operation, the main source of which, as shown by studies, is aerodynamic noise that negatively affects human health (prolonged exposure leads to impaired cardiovascular and respiratory systems, to hearing impairment, etc.) and oznikayuschy due to dynamic effects emerging from the high-flow bladed wheel in the fan coil heating elements and other parts of the air path, the distance between the fan and which is insufficient for conversion of kinetic energy into pressure energy. All this reduces the reliability and efficiency of the fan heater.

-образных стоек, на свободных концах которых закреплены керамические пластины, компаратор, к информационным входам которого подключены задатчик температуры и блок контроля температуры, подключенные к источнику питания преобразователь напряжения и управляемый переключатель, выполненный на симисторе, выход которого подключен к вентилятору и нагревательному элементу, подключенный к преобразователю напряжения помехоподавляющий блок, регулятор выходной мощности, управляющий вход которого имеет блок управления и генератор управляющих импульсов, который подключен к симистору через усилитель, причем вход компаратора подсоединен к преобразователю напряжения, выход через помехоподавляющий блок подключен к регулятору выходной мощности, а последний подключен к входу симистора последовательно через генератор управляющих импульсов и усилитель [2].Known fan heater, comprising a housing with inlet and outlet pipes, a fan installed in the housing near the inlet pipe, a spiral heating element located on a support device near the exhaust pipe, a power source connected to a fan and a heating element made in the form of at least one heating element block with a cross-section having the shape of a rhombus, assembled from separate sections of spirals, the ends of which are fixed along the length on both sides of the ceramic plates the stins and are electrically connected in parallel-serial or mixed connection with conductive jumpers, a glass-fiber thread passed inside all the spirals, a spacer installed in the middle of the heating block between the spirals, a support device in the form of two

-shaped racks, on the free ends of which ceramic plates are fixed, a comparator, to the information inputs of which are connected a temperature setter and a temperature control unit, a voltage converter and a controlled switch made on a triac connected to a fan, the output of which is connected to a fan and a heating element, connected to the voltage converter, an interference suppression unit, an output power regulator, the control input of which has a control unit and a control generator mpulsov which is connected to the triac through the amplifier, wherein the comparator input is connected to the converter voltage output via a suppression unit connected to the controller output, and the latter is connected to the input of the triac control pulses sequentially through the generator and the power [2].

 The disadvantages of this fan heater include insufficient operating efficiency and low reliability due to the complexity of the design, the complexity of the electrical connections, insufficient reliability of its elements, in particular sections of the spiral heating element, under shock loading, and a high level of aerodynamic noise due to the dynamic effects of high-speed flow coming out of the fan to closely spaced elements of the air path before kinetic transition tion of flow energy into pressure energy.

 According to the technical nature and the effect achieved, the closest to the proposed fan heater is a fan heater containing a cylindrical body, an axial fan mounted coaxially to the body, mesh inlet and outlet, respectively made in the form of a cylindrical surface of the body and end cap, heaters with fasteners made in the form of supports, with flexibility both in axial and in radial directions, for example, in the form of twisted elastic plates rigidly fixed on the body and on surfaces of heat electric heaters, a remote control unit, a casing forming a heat-shielding cavity coaxial to the body, a slotted ejector mounted on the periphery of an opening made in the rear wall of the body, a heat-shielding screen mounted on the inner end wall of the heat-shielding cavity, the rear end wall of the body and on the outer surface of the ejector, remote temperature control device for switching on and off the heaters depending on the ambient temperature and the drive located inside ejector, and the entrance area is at least twice the exit area [3].

 This fan heater is selected as a prototype of the proposed fan heater.

 The disadvantages of the prototype include the complexity of the design and, as a result, the low level of reliability, the high complexity of manufacturing, the high level of aerodynamic noise caused by the dynamic (shock) effect of the high-speed flow exiting the fan on closely located heaters and other parts of the air path, possible premature component failures that reduce work efficiency, as well as high power (up to 30 kW).

 GOST 17083-91 [4] limits the power of fan heaters to 2 kW, which corresponds to the characteristic power of fan heaters produced in countries such as the countries of the CIS, USA, Germany, Great Britain, France, Hungary, Holland, Bulgaria, etc. [5 ].

 The objective of the invention is to increase the reliability and efficiency of the fan heater.

, отношением шага t пластин к ширине В пластины в интервале

и отношением толщины Δ пластины к толщине δ резистивного слоя в диапазоне

, при этом отношение расстояния между рамами l к эквивалентному диаметру корпуса d_э выбрано в пределах

.The required technical result is achieved due to the fact that the fan heater, comprising a housing, mesh inlet and outlet, a fan, electric heaters with fasteners, a control unit and a temperature controller, according to the invention is equipped with sequentially located inside the housing and interconnected frames, one of which is mounted on it the fan is located near the entrance, and the other, in which the electric heaters are installed, is located near the outlet, the electric heaters are made in the form of a package drawn from parallel to each other, flat rectangular ceramic plates arranged one above the other, one of the surfaces of each is covered with a ceramic composite resistive layer consisting of an insulating and conducting phase, the end sides of each plate are connected electrically in parallel, and the fastening elements of electric heaters are made in the form of elastic clamps mounted on two contacts, connected through insulators with racks of the frame near the exit, and each of the plates is made with a ratio of length L to width B of the plate within

, by the ratio of the step t of the plates to the width B of the plate in the interval

and the ratio of the thickness Δ of the plate to the thickness δ of the resistive layer in the range

, the ratio of the distance between the frames l to the equivalent diameter of the housing d _e selected within

.

 The authors of the proposed fan heater are not aware of similar technical solutions, and therefore, according to the authors, the claimed combination of inextricably linked essential features that achieve the desired technical result meets the criteria of the invention “significant differences” and “positive effect”.

 The invention is illustrated in the drawing, which shows a fan heater in axonometric projection.

 The fan heater comprises a rectangular housing 1 with mesh input 2 and output 3. Inside the housing 1 there are a fan 4, for example an axial one, with an electric motor and electric heaters 5 with fastening elements 6.

 The fan heater has a remote control unit 7 and a temperature controller 8. The fan heater is equipped with frames 9 and 10 arranged in series inside the housing 1 and connected to each other. The frames 9 and 10 can be connected, for example, using studs with nuts or by any known method.

 One of the frames 9 with the fan 4 fixed on it (on sound-absorbing pads) is located near the entrance 2, and the other 10, in which the electric heaters 5 are installed, is located near the exit 3.

 Electric heaters 5 are made in the form of a package, recruited from parallel to each other flat rectangular ceramic plates. One of the horizontal surfaces of each plate is covered with a ceramic composite resistive layer consisting of an insulating and conductive phase. The end sides of each plate are electrically connected in parallel.

 The fastening elements 6 are made in the form of elastic clamps 11, mounted on two contacts connected through insulators 12 to the racks of the frame 10 near the exit 3.

, отношением шага t пластин к ширине В пластины в интервале

и отношением толщины Δ пластины к толщине δ резистивного слоя в диапазоне

. При этом отношение расстояния l между рамами 9 и 10 к эквивалентному диаметру d_э корпуса 1 выбрано в пределах

.Each of the plates is made with the ratio of the length L to the width B of the plate within the limits determined by the inequality

, by the ratio of the step t of the plates to the width B of the plate in the interval

and the ratio of the thickness Δ of the plate to the thickness δ of the resistive layer in the range

. The ratio of the distance l between the frames 9 and 10 to the equivalent diameter d _{e of the} housing 1 is selected within

.

где d_э - эквивалентный диаметр, м;
F - площадь поперечного сечения корпуса, м²;
П - периметр поперечного сечения корпуса, м [6].Equivalent diameter is defined as

where d _e is the equivalent diameter, m;
F is the cross-sectional area of the housing, m ² ;
P is the perimeter of the cross section of the body, m [6].

указанные в формуле изобретения, установлены на основе данных опыта.All relative parameter limits

indicated in the claims are established on the basis of experience.

 The use of mesh input 2 and output 3 eliminates the possibility of foreign objects getting inside the housing 1 and thereby increases the safety and reliability of the fan heater.

), тем хуже - больше скорость, больше кинетическая энергия потока, ударяющегося об него, выше уровень аэродинамического шума, снижающего эффективность и надежность работы тепловентилятора, и, наоборот, чем он дальше от вентилятора (при больших значениях

), тем лучше - выше эффективность и надежность работы тепловентилятора. Действительно, как показывает анализ, снабжение тепловентилятора последовательно расположенными внутри корпуса 1 (с уголками жесткости) и соединенными между собой рамами 9 и 10, одна из которых с закрепленным на ней вентилятором, установленным на звукопоглощающих прокладках, расположена вблизи входа 2, а другая 10, в которой установлены электронагреватели 5, расположена вблизи выхода 3, а также установка этих рам с оптимальным отношением их расстояния l к эквивалентному диаметру d_э корпуса в пределах при допустимой окружной скорости вентилятора (менее 25 м/с) позволяет:
во-первых, обеспечить простоту конструкции, которая является гарантией ее надежности;
во-вторых, благодаря оптимальному выбору расстояния между рам по неравенству

эффективно использовать процесс преобразования кинетической энергии потока, выходящего из лопаточного колеса вентилятора, в энергию давления и, как следствие этого, добиться не только существенного снижения скорости и кинетической энергии потока, но и бесшумности работы тепловентилятора, поскольку благодаря гашению кинетической энергии и исключению непосредственного интенсивного соударения потока об элементы воздушного тракта устранен аэродинамический шум, ухудшающий самочувствие и здоровье человека;
в-третьих, добиться равномерности распределения скоростей и температур потока до и после электронагревателей.The nature and degree of dynamic loading of each element of the air duct in a certain way depends on its location in the structural diagram of the fan heater - the closer it is to the fan (for small values

), the worse - the greater the speed, the more kinetic energy of the flow hitting it, the higher the level of aerodynamic noise, which reduces the efficiency and reliability of the fan heater, and, conversely, the farther it is from the fan (at high values

), the better - the higher the efficiency and reliability of the fan heater. Indeed, as the analysis shows, the supply of the fan heater is sequentially located inside the housing 1 (with stiffeners) and interconnected by frames 9 and 10, one of which with a fan mounted on it, mounted on sound-absorbing gaskets, is located near the entrance 2, and the other 10, in which electric heaters 5 are installed, is located near exit 3, as well as the installation of these frames with the optimal ratio of their distance l to the equivalent diameter d _{e of the} case within at a permissible peripheral fan speed (less than 25 m / s) allows:
firstly, to ensure the simplicity of the design, which is a guarantee of its reliability;
secondly, due to the optimal choice of the distance between the frames according to the inequality

to effectively use the process of converting the kinetic energy of the stream leaving the fan wheel to pressure energy and, as a result of this, achieve not only a significant decrease in the speed and kinetic energy of the stream, but also noiseless operation of the fan heater, since due to the quenching of kinetic energy and the elimination of direct intense collision aerodynamic noise eliminating the well-being and health of a person;
thirdly, to achieve uniform distribution of velocities and flow temperatures before and after electric heaters.

 All this increases the efficiency and reliability of the fan heater.

, отношением шага t пластин к ширине В пластины в интервале

и отношением толщины Δ пластины к толщине δ резистивного слоя в диапазоне

позволяет:
во-первых, создать компактную и безопасную конструкцию электронагревателей, обладающих, как показали испытания, высокой надежностью и эффективностью работы;
во-вторых, использовать низкотемпературные нагревательные пластины, которые являются более эффективными, малотеплоинерционными и пожаробезопасными по сравнению как с прототипом, так и с аналогами. Температура поверхности пластин не более 90^oС, максимальная температура горячего воздуха не выше 65^oС и по длине струи она быстро падает [5, с. 119];
в-третьих, обеспечить необходимую прочность, жесткость и тепловибростойкость электронагревателей, без которых немыслима надежная и эффективная работа тепловентилятора.The implementation of electric heaters 5 in the form of a package drawn from parallel to each other flat rectangular ceramic plates, one of the horizontal surfaces of each of which is coated with a ceramic composite resistive layer consisting of an insulating and conductive phase, and also plates with a ratio of length L to width B plates within the limits defined by inequality

, by the ratio of the step t of the plates to the width B of the plate in the interval

and the ratio of the thickness Δ of the plate to the thickness δ of the resistive layer in the range

allows you to:
firstly, to create a compact and safe design of electric heaters with, as shown by tests, high reliability and operational efficiency;
secondly, to use low-temperature heating plates, which are more efficient, low thermal inertia and fireproof in comparison with both the prototype and its analogues. The surface temperature of the plates is not more than 90 ^o C, the maximum temperature of hot air is not higher than 65 ^o C and along the length of the jet it quickly drops [5, p. 119];
thirdly, to provide the necessary strength, rigidity and thermal and vibration resistance of electric heaters, without which reliable and efficient operation of the fan heater is unthinkable.

 Along with this, one cannot but take into account that the reliability and efficiency of the fan heater decisively depend on how rationally the structural dimensions are selected and with what optimal pitch t the heating plates are located relative to each other. Indeed, with a small step, the number of these plates increases, which leads to an increase in the effect of mutual thermal irradiation and an increase in material consumption and cost. At the same time, with a small step, the total aerodynamic drag of the air path increases, which can cause a change in the operating mode of the fan in the direction of reducing the flow of hot air supplied to the room, and this increases the time and reduces the efficiency of heating the room. On the other hand, with a small step, an increase in the number of plates equivalent to their reservation leads to an increase in reliability, since failure of at least one plate due to mutual irradiation of neighboring plates does not lead to failure of the fan heater [7].

и

диктуется необходимостью обеспечения высокой надежности и эффективности работы тепловентилятора.With a large step, the number of plates, their mutual irradiation, the total aerodynamic drag of the air path and the material consumption of electric heaters will be the minimum possible, and the flow of hot air will be maximum, therefore, the performance of the fan heater will be the best. Thus, the performance of plates by inequalities

and

dictated by the need to ensure high reliability and efficiency of the fan heater.

повышает их прочность, адгезионную прочность их соединения, жесткость, устойчивость и тепловибростойкость, от которых зависят работоспособность и надежность как пластин, так и тепловентилятора, а то, что концевые стороны каждой пластины соединены электрически параллельно, делает каждую пластину автономной и более надежной в работе.The performance of plates and resistive layer by inequality

increases their strength, the adhesive strength of their joints, rigidity, stability and thermal and vibration resistance, which depend on the performance and reliability of both the plates and the fan heater, and the fact that the end sides of each plate are connected electrically in parallel makes each plate autonomous and more reliable in operation.

 The reliability of the fan heater depends on the reliability of its constituent elements.

 The implementation of the fastening elements 6 of the electric heaters 5 in the form of elastic clamps 11, mounted on two contacts connected through insulators 6 to the racks of the frame 10 near the outlet 3, allows you to create a strong, durable and reliable connection, at the same time acting as thermal compensators, guaranteeing protection of the plates from occurrence in them dangerous temperature deformations and stresses, which generally increases the reliability, durability and efficiency of the fan heater.

 Fan heater works as follows. The control unit 7 includes an electric motor, which rotates the blade wheel of the fan 4. At the same time, voltage is supplied to the electric heaters 5.

 The fan 4 sucks in air through the mesh inlet 2 and directs it to the electric heaters 5, where heated parallel plates transfer heat to the air flow passing through them by forced convection, heat conduction and radiation, after which the heated air through the mesh outlet 3 is fed into the heated room. In the case when the temperature of the heated air, according to the sensor, becomes higher than the set value, the temperature controller 8 turns off part of the electric heaters 5 and the temperature decreases.

 The set of inextricably interconnected and subordinate to a single goal of the essential features set forth in the claims, provides increased reliability and efficiency of the fan heater and meets the criteria of the invention.

 The manufacture of the proposed fan heater does not present any particular difficulties and can be carried out under normal production conditions.

 Currently, the fan heater has passed the prototype test phase.

Sources of information
1. US 4398082 A, 1983 - analogue.

 2. RU 2131092 C1, 09.16.1998 - analogue.

 3. RU 2124168 C1, 01/13/1998 - prototype.

 4. GOST 17083-91 (instead of GOST 17083-71). Types and main parameters of electrothermal fans - analogues.

 5. A. S. Varshavsky, L. V. Volkova, V. A. Kostylev, and others. Domestic heating electrical appliances (designs, calculations, tests). M .: Energoizdat, 1981, p. 118-125 - Electric fan heaters. Fig. 9.1 - analogue. The model of the 202S fan heater of the Fakir company (Germany) is an analogue (p. 121, 122). Fig. 9.2. - outdoor electric fan heater (Germany) - analogue. Fig. 9.3 - round electric fan heater (Holland) - analogue. Fig. 9.4 - desktop electric fan heater EK-4 (Russia) - analogue. Fig. 9.5 - electric fan heater "Veterok" (Russia) - analogue. Other analogues are also given.

 6. I.E. Idelchik. Handbook of hydraulic resistance. Edited by M.O. Steinberg. 3rd ed. M .: Engineering, 1991, 672 p. Entrance to the direct channel through a fixed louvre grille is an analog.

 7. Optimal reliability problems. Ed. Ph.D. I.A. Ushakova. M .: Publishing house of standards, 1968, p. 5-22 - no analogues were found.

 8. A.D. Svenchansky. Electric industrial furnaces. Volume 1. M.: Energy, 1975, 384 p. - no analogues were found.

Further, from clause 9 to clause 41 there are analogues:
9. DE 1297252 A, 06/12/1969.

 10. GB 1215453 A, 12/9/1970.

 11. SU 324455 A, 1971.

 12.CH 539255 A, 08/31/1973.

 13. GE 1104666, 36c, 1976.

 14. SU 544840 A, 03/22/1977.

 15. SU 603809 A, 1978.

 16. US 4151398 A, 04.24.1979.

 17. US 4,110,600 A, 08/29/1979.

 18. SU 787815 A, 12/23/1980.

 19. US 4287673 A, 09/08/1981.

 20. US 4398082 A, (NK 219-370), 1983.

 21. DE 3148870 A, 1983.

 22. SU 1177608 A, 09/07/1985.

 23. US 4,539,896 A, 1985.

 24. SU 1079962 A, 1986.

 25. EP 0183252 A2, 06/04/1986.

 26. US 4642441 A, 02/10/1987.

 27. SU 1758354 A1, 01/17/1990.

 28. SU 1562622 A1, 05/07/1990.

 29. RU 2008571 C1, 03/12/1991.

 30. RU 2008572 C1, 05.27.1991.

 31. RU 2024798 C1, 06/20/1991.

 32. RU 2056013 C1, 10.29.1991.

 33. RU 2032860 C1, 04/10/1995.

 34. RU 9400894 C1, 11.20.1995.

 35. CA 2059195 C, 1995.

 36. RU 2053457 C1, 01/27/1996.

 37. RU 94033860 A1, 08.20.1996.

 38. RU 2071639 C1, 01/10/1997.

 39. RU 2072064 C1, 01.20.1997.

 40. GB 2305500 A, 1997.

 41. RU 2122689 C1, 01/13/1998.

 42. A.N. Skanavi. Heating. M .: Stroyizdat, 1979, p. 205 - Outboard air-recirculation heating unit, fig. U111.3 - an analogue; from. 207, fig. U111.5 - schematic diagram of the automation of an air heating unit - analogue; from. 213-214 - air-thermal curtains, Fig. U111.10 - analogue.

 43. S.A. Rysin. Ventilation installations of engineering plants. Directory. M .: Mashgiz, 1961, p. 338 - air curtains - analogues.

44. Catalogs for electric fan heaters, issued in 2000-2001:
- ΩDBK. Elektrowarme kreativ. Heizkomponent. PCT Schalts - chrank - neizungen.

 - PCT Cabinet Heaters. Typenreihen HK, HC, HP. Types HK, HC, HP. 2000.

 - PCT Finned Resistor Heating Elements. - The electric fan heaters - analogues are given.

Claims (1)

A fan heater comprising a housing, mesh inlet and outlet, a fan, electric heaters with fasteners, a control unit and a temperature controller, characterized in that it is equipped with sequentially located inside the housing and interconnected frames, one of which with a fan mounted on it is located near the entrance, and the other, in which the electric heaters are installed, is located near the outlet, the electric heaters are made in the form of a packet drawn from parallel rectangular planes located one above the other x ceramic plates, one of the surfaces of each is coated with a ceramic composite resistive layer consisting of an insulating and conductive phase, the end sides of each plate are connected electrically in parallel, and the fastening elements of electric heaters are made in the form of elastic clamps mounted on two contacts connected through insulators to the frame posts near the exit, and each of the plates is made with the ratio of the length L to the width B of the plate within

, by the ratio of the step t of the plates to the width B of the plate in the interval

and the ratio of the thickness Δ of the plate to the thickness δ of the resistive layer in the range

, the ratio of the distance between the frames l to the equivalent diameter of the housing d _e selected within

.