DE2644937C2 - System for heating liquid and gaseous flowing media - Google Patents

Description

The invention relates to heating elements based on the resistance heating method, in particular on a system for heating liquid and gaseous flowing media, which none Additions are added.

In semiconductor technology, the deionized, highly purified water is used in the production of Semiconductor devices widely used.

It is known that the washing of semiconductor wafers and crystals is most productive with deionized highly purified hot water. In this case increased the washing quality, the acid residues dissolve better; furthermore, the appearance of the plates and improves Crystals and it increases the percentage of finished devices. The deionized water with high However, the degree of purification has an increased absorption, which is why it was heated up to the temperature from 70 to 80 ° C without the addition of admixtures up to now practically not possible.

The invention solves the problem mentioned.

The invention can be used in the radio industry, medicine and the food industry will.

So the invention can e.g. B. in medicine as a system for heating a dialyzing liquid (Saline solutions) for hemodialysis to be performed using the »artificial kidney« device used.

In the food industry, the invention be used in the pasteurization of milk, beer and fruit juices.

Until now, in semiconductor technology, deionized water has been used in helical heaters warmed up. Such systems have large dimensions, require large amounts of help-resistant special alloys, have a low degree of efficiency and a low performance. In addition, they do not make it possible to obtain hot deionized water other than none Additions are added.

The plant is known for warming up. deionized water from »Aqua Media« (see the magazine "Solid State Technology", 3, '.974, p. 12, 13).

The known system contains a consisting of a bundle of capillary tubes hydrogen fluoride heat exchanger, inside which the deionized Water flows The said heat exchanger is in a container with a liquid of high Heat capacity housed which when heated with metallic heaters a large amount of heat stores and transfers them to the deionized water via the heat exchanger

The known system has a complicated construction

and requires a large amount of for their production expensive heat-resistant alloys. The setting and testing the system are labor-intensive and take a lot of time.

A system for heating liquid and gaseous media (SU-PS 1 88 601) is also known using a heating element with a conductive coating.

The known system contains a panel, inside which a heating element is housed, which has a housing made of an insulating material on its outer surface conductive coating is applied, which is connected to the electrical feed system by means of conductive rails Housings are connected to a system for supplying and removing a medium.

In the system mentioned, the heating element is designed in the form of a cylinder with double walls, between which there is a vacuum

In the direction of the axis of the heating element inside the cylinder, a metal tube is arranged through which the medium to be heated flows d. H. the conductive coating is from the medium by a Air interlayer and the wall of a metal pipe separated.

The medium to be heated flows inside the Metal pipe, which is only connected to the electrically conductive Coating developed radiant energy is heated. Most of the thermal energy is used for Warming the cladding and other parts of the Plant consumes the efficiency of such Heating element is a maximum of 4%, in addition, the

called plant complicated to manufacture

Also known is a hollow body heater for glass surfaces of hollow glass bodies in the form of a applied and then burned-in silver coating in the form of conductor tracks (DE-GM 76 02 010).

The hollow body that can be heated in this way is a cylindrical cup with a bottom.

The problem of heating a medium flowing through the vessel does not arise with this hollow body heater.

The invention is based on the object of a System for heating liquid and gaseous

to create flowing media with which the warming of particularly pure liquid and gaseous flowing media with high performance of the system and

is guaranteed with a high degree of efficiency.

This object is achieved in that the system for heating liquid and gaseous flowing media, which contains a casing, in the interior of which at least one heating element is housed is, which has an insulating housing on the outer surface of a conductive coating is applied and its inlet and outlet nozzle with are connected to a system for supplying and removing a medium, according to the invention Housing of the heating element in the form of a combination is formed by successively flowed through spaces of variable cross-section, which are sequentially through Intermediate webs with rails attached to them for the supply of electrical voltage to the conductive upper cable are connected to each other.

The turbulence of the flow due to large changes in the cross-section of the vessel and the large surface area the, for example, spherical extensions cause a significantly improved heating of the medium flowing through the vessel, compared e.g. B. with a cylindrical vessel or with a helical heater.

It is useful that in the system for heating liquid and gaseous media, the ratio of the maximum dimension of a space with variable cross-section with respect to its central axis to the maximum The dimension of an intermediate web is between 15 and 3

It is advantageous to have a number of heating elements in the enclosure of the present installation arranged, which are combined into a block with the help of collectors, which with the inlet and outlet nozzle of the insulating housing of each heating element are connected.

It is possible to connect each inlet and outlet connection of the heating element with the corresponding one Run the collector in the form of a sleeve made of fluoroplastic, which in the cold state on the corresponding nozzle is pressed on, and with an elastic clamping sleeve that encompasses the connection to strand.

The present system for heating liquid and gaseous flowing media allows the Performance when heating particularly pure liquid and gaseous flowing media compared to z. B. to increase cylindrical heaters and thus to reduce the consumption of electrical energy. You need also a low cost of expensive metals for their production.

The invention is based on an exemplary embodiment with reference to the drawings explained. It shows

1 shows the heating system according to the invention liquid and gaseous media with a heating element;

Fig.2 the lining of the heating element according to the Invention;

3 shows the system for heating liquid and gaseous media with three heating elements, which are combined to form a block tvM with the help of collectors, according to the invention;

4 shows the connection module of one of the nozzles of the heating element with the collector according to the invention.

The system for heating liquid and gaseous media contains a cladding 1 (Fig. 1), inside of which a heating element 2 is housed, which has an insulating housing 3 aii., On the outer surface of which a stroaiieitender coating 4 p. Is applied, which by means of StromleitittT 'rails 5 with an electrical feed system 6 connected ^ &.

O:; ^r , housing 3 of the heating element 2 is made in the voflisgeiiuen variant of the system

Qiwrz made, the conductive coating 4 is on

the outer surface of the housing 3 applied ur.j does not come into contact with the medium to be heated. This allows the heating of particularly pure media in a closed room, without these admixtures being added.

The inlet 7 and the outlet nozzle 8 of the heating element 2 are with a system 9 for Supply and discharge of the medium connected. The arrows 10 and 10 'show in which direction the Medium is fed into the system or discharged from it.

According to the invention, the heating element 2 is a combination of spaces 11 (Figure 2) of variable cross-section, for. B. in the form of balls executed, which in turn by intermediate webs 12 with. attached rails 5 (Fig. 1) for cft? Supplying the electrical voltage to the conductive coating 4 are connected to one another.

The ratio of the maximum dimension of a room 11 (Fi g. 7) with respect to its central axis, z. B. the diameter of a ball, the maximum dimension of the intermediate web 12 is between 1.5 and 3.

A variant of the system is to be explained below, in which the casing 1 the specified number of heating elements 2 (Fig. 3),

z. B. three elements 2 _U 2 ₂ , 2 ₃ , are arranged, which are combined into a block with the help of collectors 13 and 14, which with the inlet connection 7 _U T ₂ , 7j and the outlet connection 8 |, 82, 83 of the heating elements 2τ, 22,23 are connected.

The connection of each inlet port 7 |. 7 ₂ , T _{1 of} the heating elements 2 \, 2 ₂ , 2] with the collector 13 is in the form of a sleeve 15 (Figure 4), for. B. made of fluoroplastic in the cold state on the corresponding nozzle 7 \, T ₂ or 7 _{3 is} pressed, and an elastic, this connection comprehensive clamping sleeve 16 is executed.

Since fluoroplastic is a cold flowing substance, the

Creation of a tight connection with the quartz nozzle, e.g. B. 7 |, a constant pressing force is required, those over the surface of the pressed-on fluoroplastic sleeve 15 is evenly distributed. This function is exercised by the elastic clamping sleeve 16 which, for. B. made of rubber is made without the quartz nozzle 7 | destroyed.

The connections of each inlet connection 81, 82, 83 of the heating elements 2 1, 2 ₂ , 2 ₃ with the collector 14 are designed similarly.

The heating of liquid and gaseous media in the present system takes place as follows. The medium enters the system in the direction of arrow 10 and fills the heating element 2 (Fig. 1).

The temperature of the element entering the heating element

Medium is always below the temperature of the environment. This creates a temperature gradient whose vector is directed towards the side of the highest temperature.

When the voltage is applied by means of rails 5 to the current-carrying coating 4, the latter heats up and develops heat, the heat flow having the direction b5 which is opposite to the direction of the vector of the Tempeiuturgradietiteii, ie ic aas inside the housing 3 of the heating element 2. The · Length of the emitted wave of the conductive coating

λ = 4-4.5 μm

The medium to be heated begins, after it has ^{warmed up to 100 to 150 0} C, to radiate the heat itself with a wavelength of λ = 7 to 8 μm.

The conductive coating 4, e.g. B. tin dioxide, has a reflectivity in the infrared region of the spectrum of electromagnetic vibrations. The maximum reflectivity of the conductive coating 4 is shown at wavelengths of λ = 8 μm and λ = 16 μm. Therefore 80 to 90% of the radiation energy emitted by the water is reflected by the conductive coating 4.

The medium entering the heating element 2 also changes its position at the locations of the annular webs 12 average outflow velocity, leading to the transition from a laminar flow to a turbulent one leads.

When the laminar flow of a medium, e.g. B. deionized water, heated, so is the Transfer of heat into the interior of the stream is delayed because the coefficient of thermal conductivity of water is extremely low. In this case, heat; only a thin surface layer of the laminar Water flow, while in the inner part of the flow the heat is only transferred by means of radiation.

In the transition to a turbulent flow, the heat energy is transferred to the medium by means of radiation, Transferring thermal conductivity and convection. This creates a quick and powerful heating of the flowing medium guaranteed. The total efficiency of the heating element, below Consideration of reflective properties of the coating 4 and the presence of the turbulent Flow, reaches 97%.

The use of spherical spaces as volume-variable spaces II ensures a larger one Heating surface of the conductive coating 4 with small dimensions of the housing 3 of the heating element 2. The hollow ball has a maximum strength limit under internal stresses that caused by the medium flowing under pressure,> which makes it possible to reduce the thickness of the wall for a choose hollow sphere minimal.

The range of the ratios of the maximum dimensions of the space 11 of variable cross-section to the maximum Measure of the intermediate web 12, which makes up 1.5 to 3, depends

in from the degree of turbulence of the liquid flow, which is im Inside the heating element 2 flows, and the density of the flowing through the Stromleitcnden coating 4 electric current.

When expanding the above-mentioned range, i.

r, when reducing a maximum diameter of the Intermediate web 12 increases the turbulence of the flow, but it also increases the density of the through current flowing to the conductive coating 4 and it reaches a critical value at which the coating 4

: o burns.

If this range is reduced, i. H. with enlargement of the maximum diameter of the web 12, the current density decreases, which is particularly favorable for the effect of the coating 4, but at the same time

_> -, the degree of turbulence of the flow decreases, what to reduce the heat transfer from the Housing would lead here.

The L * · Hung of the plant increases in direct Depending on the number of / u using

κι heating elements 2.

The system allows particularly pure media, such. B. deionized water, without the addition of additives to heat with high efficiency. It does not require a large number of special heat-resistant ones

υ alloys for making Hei.:c!eme !! ^; - * n Thus, only a few dozen grams of such an alloy are required for the system with a volume of 100 l / h. The system has small dimensions, is simple and economical to manufacture.

For this purpose 3 sheets of drawings

Claims (3)

Patent claims: 1. System for heating liquid and gaseous flowing media that have a cladding contains, in the interior of which at least one heating element is housed, which is an insulating housing has, on the outer surface of which an electrically conductive cover is applied, and its input and Outlet nozzles are connected to a system for supplying and removing a medium, characterized in that the housing (3) of the heating element (2) is in the form of a combination of spaces flowed through one after the other variable cross-section is formed, which in turn by intermediate webs (12) with attached rails (5) for the supply of a electrical voltage to the electrically conductive coating (4) are interconnected. 2. Installation according to claim 1, characterized in that the ratio of the maximum dimension of a space (!!) with a variable cross section with respect to its central axis to the maximum dimension of the intermediate web (12) is between 1 5 and 3 3. Installation according to claim 1 or 2, characterized in that in its casing (1) a number of heating elements (2) is arranged, which are combined into a block with the help of collectors (13) and (14) which are connected to the inlet connection (7 _{) t} 7 ₂ , 7 ₃ ) and outlet nozzle (8 |, 82,8j) of the insulating housing of each heating element (2) are connected.