RU2529894C1 - Heat energy radiator - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: heat energy radiator is made as a unified one-lamp module fitted by a reflector in the form of a hollow case with branch pipes for the supply and withdrawal of cooling agent, an optically transparent screen is made from glass with the spectrum absorbing additives, and the device for cooling agent supply and withdrawal is equipped by a channel to feed in an absorbing pigment, the lamp is a gas-discharge one, its shell is made from the material with specified values of absorption and dispersion indices, its current leads are made as collet clamps.

EFFECT: simplified regulation of heat energy radiator and increased service life.

4 cl, 2 dwg

Description

The invention relates to mechanical engineering and can be used to create and form new ceramic and composite materials, for example, by the method of selective beam sintering, and also to heat the surfaces of various objects to the required temperature by the method of radiant and convective heat transfer.

For example, to diagnose the characteristics of heat resistance and heat resistance:

- exploited metals;

- composite and ceramic materials;

- coatings based on them, in particular, when creating heat-, fire-retardant, heat-insulating special equipment;

- in the development of heat-loaded elements of industrial equipment and vehicles.

And also in those areas of technology where there are increased requirements for theoretical and experimental studies of the radiative and reflective characteristics of products made of various materials or having different coatings.

The prior art heat energy emitter (patent RU2172453, published 11/29/1999), consisting of a heating element, a reflector in the form of a paraboloid, thermal insulation located on the surface of the reflector on the back of the heating element over its entire area, and a screen fixed across the axis of symmetry of the reflector in front of the heating element along the entire length of the latter.

Such a radiator of thermal energy allows to increase the efficiency by increasing the density of the heat flux from the side of the radiator to the object and thereby eliminating the energy loss due to dissipation from the heating element outside the object; reduce the cost of electrical energy to ensure heating of the facility during testing; reduce the heat gain to the refrigerator from the side of the reflector and the flow of liquid nitrogen during tests in a vacuum thermal chamber.

The disadvantage of this device is the limitation on the area of irradiation on the surface of the test object, insufficient power density and limited (solar) spectrum of the radiant energy supplied.

Also known are light-beam quartz halogen incandescent lamps, xenon ultra-high-pressure spherical arcs with combined and air cooling (VA Frolov Light-beam technologies for heat treatment of materials // Photonics. Technological Equipment and Technologies, 2010, No. 3, pp. 23-26). The emission spectrum of arc xenon lamps is close to the sun, but with intense radiation in the ultraviolet and short-wave (0.8-2.0 microns) infrared region. A favorable combination of spectral and energy characteristics of xenon arc lamps opens up wide prospects for their use in solving various technological problems in mechanical engineering and instrument making. Light-beam lamps are usually referred either to normal-circular, or to normal-band heat sources.

A disadvantage of the known lamps is that they operate in a narrow range of power changes, which limits the possibility of controllability of heating, as well as the fact that due to multiple overloads, which determine the hard temperature of the glass bulb and erosion of the electrodes, the resource of the radiation source drops sharply.

The closest in technical essence to the present invention include heaters according to the patent (RU1342210, published 11/15/1994), adopted by us for the prototype, used in heat chambers for testing machines. The heater is made in the form of a lamp with current leads and contains an optically transparent screen made in the form of a cylinder mounted coaxially to the lamp, as well as means for supplying and discharging refrigerant into the gap between the screen and the lamp.

The disadvantages of the described heater are: an indefinite range of the radiation spectrum, uncontrollability of the magnitude and direction of the heat flux; the impossibility of a modular arrangement of heaters for irradiating objects of a large area - of the order of a square meter. In addition, the use of these lamps with a wide spectrum of radiation does not allow simulating the thermal radiation load, which is typical for the normal operation of various thermal power equipment. For example: simulation of heat flux in the ultraviolet range upon entry into the atmosphere of aircraft; tests for materials of combustion chambers of diesel engines or turbines in the near infrared range.

The objective of the invention is to reduce energy costs during field testing of objects, ensuring controllability of the heat flux, as well as expanding the interval of change in power with increasing service life of the heater.

The essence of the proposed technical solution lies in the fact that the radiator of thermal energy, containing a lamp with a shell and current leads at the ends, placed together with them in a stream of refrigerant, an optically transparent screen made of glass, means for supplying and removing refrigerant into the gap between the screen and the lamp , according to the invention is made in the form of a unified single-tube module, equipped with a reflector in the form of a hollow body with pipes for supplying and discharging refrigerant, an optically transparent screen is made of glass with bavkami spectral absorbers, and means for supplying and removing the coolant channel is provided with input absorber pigment, wherein the discharge lamp is formed, its sheath material with predetermined values of absorption and scattering parameters, and the current leads in a collet.

In addition, the differences of the invention consist in the fact that:

- the shell of the discharge lamp is made of leucosapphire with an absorption index of not more than 0.3 1 / m and a thermal conductivity of at least 1.5 W / (m · K);

- the content in the refrigerant of the pigment absorber in the form of filtering dispersed particles of organic or non-organic nature (water-soluble dyes or polydisperse particles) with a concentration of up to 5%;

- as additives of spectral absorbers in the glass of an optically transparent screen, zirconium, aluminum, and silicon oxides were used, while the optical thickness h of the screen — the outer cylindrical shell — is determined from the relation

$$h\ge \frac{\mathrm{one}n\left(\tau \right)}{\sqrt{3\cdot \left(\mathrm{one}+\frac{\sigma }{k}\right)}}$$

where h is the optical thickness of the screen shell;

k, σ are the averaged over the spectrum indicators (coefficients) of absorption and scattering;

τ is the integral transmittance of the screen.

The technical result of the invention is:

- providing a given spectral transmittance of the shell of the radiator of thermal energy by modeling the spectral characteristics, by applying a two-stage filter:

- the first cascade (rough) - the outer shell (optically transparent screen) is made of glass with the addition of appropriate radiation absorbers based on zirconium, aluminum, silicon oxides (constant radiation filter);

- the second cascade (thin) is provided by appropriate additives of organic (inorganic) absorbers, for example, water-soluble dyes or polydisperse particles, which are introduced into the refrigerant with a concentration of up to 5% (a liquid filter varying in spectrum), which allows you to adjust the spectrum even during the experiment;

- the maximum achievable levels of forcing the power of the radiation source - gas discharge lamp, are determined by the temperature regime of its shell - inner shell. The use of transparent materials with a low absorption coefficient and high thermal conductivity, such as leucosapphire, can significantly increase the power of the radiation source (more than doubled in forced modes), and therefore, the radiation flux density up to 4 MW / m ² , providing an increase in the radiation flux density on the surface of the heated object, as well as the formation of a given radiation field;

- a significant increase in the life of the heater (up to tens of minutes) is directly related to the elimination of the causes that cause the lamp shell to overheat above 1200 ° C, as well as high-current current leads. Placing a gas-discharge lamp together with current leads in the cooler stream dramatically improves the temperature state of the heat-stressed lamp shell and high-current electrodes, which allows repeatedly (10 ... 12 times) boosting the lamp power, due to which an increase in the radiation flux generation is achieved;

- the choice of the absorber achieves the regulation of the spectrum of radiation acting on the object, including during the heating process, which ensures the desired spectral distribution of the thermal radiation of the heating source. The introduction of absorbers into the material of the casing of the gas discharge lamp toughens the temperature regime; however, a rational cooling scheme increases the effective absorption coefficient (coefficient) to 0.3 m ^-1 without violating the permissible temperature regime of the casing. This allows absorbers to be introduced into the material of the outer shell to form the desired radiation spectrum up to obtaining a lattice spectrum containing a set of narrow emission bands;

- the radiation source together with the reflector represent the finished structure - a single-tube module with standardized units for supplying electricity and refrigerant. This allows unitary modules to be assembled into multi-tube blocks for heating surfaces of complex geometric shapes (for example, wing profiles of hypersonic aircraft or gas turbine blades).

The essence of the proposed device is illustrated by drawings, which depict:

figure 1 - radiator of thermal energy in the form of a unified single-tube module complete with a gas discharge lamp and a water-cooled reflector;

figure 2 is a section along aa of the emitter of thermal energy. The proposed design of the thermal energy emitter consists of a unified single-tube module, including a gas discharge lamp 1 with current leads along its ends, made in the form of collets 2, placed together with the lamp 1 in a stream of refrigerant (for example, industrial water), and a reflector made in the form of a hollow case 3 with nozzles 4 for pumping refrigerant through its cavity 5, while the hollow body 3 is mounted with the possibility of adjustment relative to the irradiated surface of the object (not shown). Coaxial to lamp 1, a cylindrical screen 6 (outer shell) of optically transparent material (glass) with the addition of spectral absorbers is installed. The hollow body 3 of the reflector is equipped with a means for supplying and discharging the refrigerant into the gap 7 between the cylindrical screen 6 (outer shell) and the gas discharge lamp 1 made with a channel 8 for pumping the refrigerant through the gap 7. The channel 8 is connected to the corresponding pipe 9 of the refrigerant supply. The means for supplying and discharging the refrigerant is provided with a channel 10 for introducing the pigment absorber, while the pigment absorber (in the form of particulate filter particles of organic or inorganic nature) is introduced into the refrigerant with a concentration of up to 5%. To the current leads of the lamp 1, electrical cables (not shown) are docked. The lamp shell is made of material with an absorption index of not more than 0.3 1 / m, a scattering index of less than 0.01 1 / m and a thermal conductivity of at least 1.5 W / (m · K), for example, from leucosapphire.

In the case of using polydisperse particles as filter additives, for example, oxides of zirconium, aluminum, silicon (i.e., the organization of a dispersion filter), the optical thickness h of the screen - the outer cylindrical shell is determined from the ratio

$$h\ge \frac{-\mathrm{one}n\left(\tau \right)}{\sqrt{3\cdot \left(\mathrm{one}+\frac{\sigma }{k}\right)}}$$

where h is the optical thickness of the screen shell;

k, σ are the averaged over the spectrum indicators (coefficients) of absorption and scattering;

τ is the integral transmittance of the screen.

The radiator of thermal energy operates as follows.

After installing the irradiated object, voltage is supplied through the electric cables to the current leads of lamp 1, made in the form of collets 2. Before starting the high-voltage pulse of lamp 1 through the pipe 9, refrigerant is supplied, which through channel 8 enters the collets 2 of the current leads of lamp 1, cooling them, and then into the gap 7 between the lamp 1 and the cylindrical screen 6, cooling the latter. The hollow body 3 of the reflector is cooled by pumping technical water through its cavity 5 by means of nozzles 4. Modeling of the spectral characteristics is ensured by introducing the appropriate additives of absorbers into the refrigerant (liquid filter) through channel 10, which makes it possible to adjust the spectrum even during the experiment.

High-intensity radiation heating installations based on the proposed unified single-tube module allowing multiple power boosting and adjustment of the radiation flux density due to changes in the optical characteristics of the internal and external shells of the thermal energy emitter, as well as pigment with a given absorption, have the greatest prospects in the field of testing and studying the heat-resistant characteristics of structures. in the gap between the screen and the lamp.

In addition, a design feature of the emitter module is the ability to quickly change the radiation source without dismantling the module itself, as well as collet clamps of high current leads, which reduce contact resistance and, consequently, heat generation at high operating currents (up to 500 A). This helps to reduce heat loss, increase efficiency, improve the temperature of the electrodes and the associated increase in the resource of radiation sources.

Thus, the use of this technical solution in the national economy allows you to:

- promptly change the thermal energy of the emitter and thus provide a predetermined temperature for heating the surfaces of irradiated objects;

- implement the high-temperature heating mode for tens of minutes;

- create installations for heating fragments of structures with a characteristic size of the order of a square meter on the basis of standardized single-tube modules;

- integrate with devices of static and dynamic loading of the structure, which allows you to implement modes of complex effects.

A distinctive feature of the design of the emitter module is the ability to quickly change the radiation source without dismantling the module itself, as well as collet clamps of high current leads, which reduce contact resistance, and, consequently, heat generation at high operating currents (up to 500 A). This helps to reduce heat loss, increase efficiency, improve the temperature of the electrodes and the associated increase in the resource of radiation sources.

Claims (4)

1. The radiator of thermal energy containing a lamp with a shell and current leads at the ends, placed together with them in a stream of refrigerant, an optically transparent screen made of glass, means for supplying and removing refrigerant into the gap between the screen and the lamp, characterized in that it is made in the form of a unified single-tube module equipped with a reflector in the form of a hollow body with nozzles for supplying and discharging refrigerant, an optically transparent screen is made of glass with additives of spectral absorbers, and the means for supplying and from ode refrigerant channel is provided with input absorber pigment, wherein the discharge lamp is formed, its shell - of a material with given values of absorption and scattering parameters, current leads and - a collet. 2. The emitter according to claim 1, characterized in that the casing of the discharge lamp is made of leucosapphire with an absorption index of not more than 0.3 1 / m, a scattering index of less than 0.01 1 / m and a thermal conductivity of at least 1.5 W / ( mK). 3. The emitter according to claim 1, characterized in that the pigment absorber in the refrigerant is made in the form of filtering dispersed particles of organic or inorganic nature (water-soluble dyes or polydisperse particles) with a concentration of up to 5%. 4. The emitter according to claim 1, characterized in that the additives of spectral absorbers in the glass of the optically transparent screen are used oxides of zirconium, aluminum, silicon, while the optical thickness h of the screen - the outer cylindrical shell is determined from the ratio
$$h\ge \frac{-\mathrm{one}n\left(\tau \right)}{\sqrt{3\cdot \left(\mathrm{one}+\frac{\sigma }{k}\right)}}$$

where h is the optical thickness of the screen shell;
k, σ are the averaged over the spectrum indicators (coefficients) of absorption and scattering;
τ is the integral transmittance of the screen.

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