WO1991011665A1

WO1991011665A1 - Heat generator-exchanger

Info

Publication number: WO1991011665A1
Application number: PCT/EP1991/000160
Authority: WO
Inventors: Giovanni Zullo
Original assignee: Termotecnologie Avanzate S.R.L.
Priority date: 1990-02-01
Filing date: 1991-01-29
Publication date: 1991-08-08
Also published as: EP0478717A1

Abstract

The heat generator-exchanger comprises a vacuum pipe bundle (4) containing a substance with convective properties. An end part of the pipe bundle (4) is associated with heating means (5), and the remainder is arranged so as to be able to exchange heat directly and/or indirectly with an enclosed space or other materials (for example air or water). The substance is subjected to a convective motion due to heating with evaporation and, by diffusing along the entire bundle (4), causes it to exchange heat.

Description

HEAT GENERATOR-EXCHANGER Technical Field

The present invention relates to a heat generator- exchanger, and in particular to a radiating and/or convective vacuum-pipe heat generator-exchanger. Background Art

It is known that various types of heating devices which generally use transmission by convection or radiation are currently used for heating enclosed spaces.

Heating elements, such as radiators and radiating panels, are connected to a system which supplies them with a convection fluid. The fluid is used for heating the external surfaces of radiators and/or for raising the temperature of radiating panels to the operational radiation temperature.

Independent electrically powered devices for heating a convection fluid contained in a heat exchanger are furthermore known and are mostly used to heat single rooms.

In other independent devices, electric resistors are associated with fans which expel the heated air into the room to be heated. As known, the above mentioned types of system require, for their operation, various devices such as pumps, circulators, refillers etc., for which a certain degree of energy consumption as well as periodic maintenance are naturally necessary. The pipes are furthermore filled with a convection liquid, usually water, at atmospheric pressure, and are therefore subject to corrosion.

In the case of radiating-panel systems, an inherent problem exists; i.e., up to three hours of heating are required in order to reach normal running conditions, and when said systems are switched off, they cool down in no less than the same amount of time.

Furthermore, in radiating-panel systems, the fact may occur that if one or more of said radiating panels is bypassed, the entire system may be rendered operationally unbalanced, i.e., the bypassing of one panel may cause the over-heating of one or more successive panels etc..

As regards independent or free-standing electrically powered devices, they are subject to such high energy consumption that their use is usually not convenient. Disclosure of the Invention

Accordingly, an aim of the present invention is to overcome the drawbacks encountered in the prior art devices by providing a heat generator-exchanger which requires no connection to heating convection fluids for its operation.

Within this aim, an object of the invention is to provide a heat generator-exchanger which is characterized by high energy efficiency.

An important object of the invention is to provide a heat generator-exchanger which has an immediate-readiness response, whereby it is capable of eliminating heat inertiae for its startup and shutdown.

A further object of the invention is to provide a heat generator-exchanger which completely eliminates the risk of pipe corrosion which affects known heating systems.

Another object of the invention is to provide a heat generator-exchanger which does not require pumps, circulators, refillers etc. for its operation.

Yet another object of the invention is to provide a heat generator-exchanger which requires reduced mechanical maintenance.

Another object of the invention is to provide a heat generator-exchanger which is particularly suitable for heating civil and industrial environments and can also be used for heating, for example, caravans, mobile homes, boats, greenhouses, etc.

A further object of the invention is to provide a heat generator-exchanger which can be manufactured at low cost with conventional manufacturing facilities;

This aim, these objects and others which will become apparent hereinafter are achieved by a heat generator- exchanger, characterized in that it comprises at least one vacuum pipe bundle containing a substance with convective properties, an end portion of said at least one pipe bundle being associated with means for heating said substance, for causing its evaporation and a convective motion, the remainder of said pipe bundle being arranged for exchanging heat with at least one medium. Said remainder of said pipe bundle is advantageously arranged for imparting heat, either directly and/or indirectly, to a medium such as an enclosed space or other materials.

Advantageously, said at least one vacuum pipe bundle is connected, on the heated side, to at least one reservoir tank which contains said substance with convective properties and, on the other side, to at least one unheated tank, suitable for collecting condensate and being associated with means for transferring said condensate to the reservoir tank through natural or forced pathways. Brief description of the drawings

Further characteristics and advantages of the invention will become apparent from the detailed description of some embodiments thereof, illustrated only by way of non- limitative example in the accompanying drawings, wherein: figure 1 is a diagram of a first embodiment of the heat generator-exchanger used as a heater fan; figure 2 is a diagram of a second embodiment of the heat generator-exchanger used as warm air generator; figure 3 is a perspective view of a third embodiment of the heat generator-exchanger according to the invention, used for heating by radiation; figure 4 is a schematic side view of the heat generator-exchanger of figure 3; figures 5, 6 and 7 are schematic sectional views of possible embodiments of the radiating panel of the heat generator-exchanger of figures 3 and 4. Wavs of carrying out the Invention

With reference to the above figure 1, a metallic box¬ like structure, generally indicated by the reference numeral 1, is internally provided with two regions, respectively a primary region la and a secondary region lb.

A heated reservoir tank 2 is present in the primary region la and an unheated tank 3 is present in the secondary region lb.

A bundle or plurality of finned pipes 4 is arranged in the upper part of the structure 1 and connects the tanks 2 and 3.

Another smooth or finned pipe 13 hydraulically connects the tanks 2 and 3 in the lower part. A burner 5 is arranged in the primary region la below the heated tank 2 and is coupled to known control and safety devices which .are required for its. operation and are generally indicated by 6. In the upper part, with respect to said burner 5, there is a coupling 7 for a burnt fuel exhaust pipe.

In the secondary region lb, said pipe bundle 4 is connected to the unheated tank 3 which collects the condensate. Said condensate, by means of the connection provided with the pipe 13, returns to the heated tank 2 after being cooled.

In the secondary region lb, said pipe bundle 4 is interposed between an air outlet grid 8 and a ventilation apparatus which comprises a fan 9 with a respective actuation motor 10 and an air intake 11 with a filter 12.

The operating concept is as follows: the system composed of the tank 2, the tank 3, the finned pipe bundles 4.and the connecting pipe 13 is assembled and constitutes a sealed unit.

A vacuum is produced in said system and a precisely determined amount of a substance (for example water) is introduced while maintaining the vacuum; as an alternative, the substance can be introduced first and vacuum can be provided subsequently.

The introduced substance is thus confined in the tank

2, in the tank 3 and in the connecting pipe 13, whereas the entire pipe bundle 4 is empty and subjected to a negative pressure. In such conditions the system is in equilibrium, with the liquid at the same level and at the same temperature in the tanks 2 and 3.

By heating the tank 2, the liquid contained therein evaporates, and the vapor tends to occupy all the available volume, thus diffusing into the pipes 4, which are empty.

The effect of the forced ventilation or of the natural convection removes heat from the pipes, causing the vapor contained therein to condensate.

This condensation creates a new vacuum (or alters the pressure conditions in that region) , so that new vapor occupies the place of the condensed vapor.

The condensate thus obtained flows toward the tank 3 and from said tank, due to the difference in pressure, which is a function of the temperature and of the head, returns to the tank 2.

Alternatively, the pipe 13 can be provided with a pump which causes the fluid transfer from the tank 3 to the tank 2 in a forced manner.

The fan 9 generates a current of air which strikes the pipes 4 and after heating is introduced into the enclosed space by means of the outlet grid 8.

If the fan is eliminated, one obtains a thermal convection unit which operates exclusively by virtue of the convective motions of the air. In the embodiment suitable for constituting a warm air generator, illustrated in figure 2, the generator-exchanger in practice differs from the preceding one in that a connection 108 for a pipe for conveying air and distributing it to various enclosed spaces is provided in said generator in replacement of the outlet grid 8. Considering now the above mentioned figures 3 to 7, a third embodiment of the exchanger according to the invention comprises a bundle of pipes 201 which are closely connected to a metallic panel 202 which is constituted by a plate, the ends whereof are connected to a heated tank (boiler) 203 on one side and on the other side to an unheated tank 204; a burner 205, with other systems suitable for heating, is associated with the heated tank 203.

According to the invention, the two tanks 203 and 204 are connected downwardly by means of a condensate return pipe 206.

As can be seen in figure 3, the panels 202 are furthermore covered in an upward position by an insulation 207 which is suitable for limiting heat losses. The panels can be mutually connected until they constitute strips of considerable length and can extend on a single side of the heated tank 3 or on both sides thereof.

Once vacuum has been produced and the substance has been introduced, the generator is in the same conditions described previously; the substance in fact occupies the tanks 203 and 204 and the connecting pipe 206 below them, but does not occupy the pipes 201, which are empty and subjected to a negative pressure.

By heating the tank 203 associated with the burner 205, the vapor thus produced is transferred into the pipes 201, whereby, via condensation it imparts heat thereto.

In turn, said pipes heat by conduction the radiating panel 202 which is connected thereto, and the entire system is thus, raised to the required radiation temperature (from approximately 40 degrees Celsius to approximately 350 degrees Celsius) .

Appropriate devices are provided for operation and for the control and adjustment of the required temperature parameters. The vapor which has condensed in the pipes flows toward the unheated tank 204 and returns from said tank into the heated tank 203 by means of the connection 206.

Due to the length of the system, it is possible to insert one or more unheated tanks along said system. The system is completed by a combustion chamber 208 and by fume exhaust ducts 209 which extend therefrom.

Said chamber 208 is necessary when one wishes to provide a balanced combustion in which the air for combustion is drawn from the outside. With particular reference to figures 5, 6 and 7, the radiating panel 202 can be manufactured in various shapes which are indicated in cross section by the numerals 202a, 202b and 202c respectively.

As in the preceding cases, a vacuum is provided in the pipes of the bundle 201.

At this point it should be stressed that the heat generator according to the invention, in all its embodiments, can comprise trap systems for the air and for the non-condensable substances, as well as devices suitable for eliminating any presence or trace of hydrogen in the system.

The internal surfaces of the heated tank must furthermore have provisions and/or devices and/or treatments suitable for forming nucleation of the vapor, the entire system possibly also containing substances or treatments suitable for facilitating the ability of the exchange surfaces to be subjected to wetting.

.Finally, both temperature- and pressure-based checks may be performed. It should also be noted that a further embodiment of the heat generator-exchanger can provide the exclusive presence of the pipe bundle, which extends both in the primary region and in the secondary region and is partially or totally filled with the substance having convective properties.

The pipes of said bundle are tight sealed at their ends.

In this case, the operating principle is as follows: the effect of the combustion achieved with the burner heats the part of the pipes which is associated therewith and consequently heats the convective substance contained therein.

Said substance, by convection in the pipes, distributes along the entire length, therefore heating also the part which is not directly in contact with the flame.

The effect of heating is the formation of vapor inside the pipes; said vapor diffuses within the available space, imparting heat to the outside and condensing.

The condensate thus formed flows back into the heated part, and the cycle resumes.

The above described type of generator-exchanger is characterized, with respect to those currently commercially available, by high efficiency and by its independent operation, since it requires no connections to a system for distributing a heating convection fluid. The convective substances contained are never in contact with the atmosphere, thus eliminating the risks of corrosion.

The generator-exchanger is furthermore characterized by the absence of all the auxiliary devices present in current ones, and this naturally constitutes an important energy saving.

Required maintenance is furthermore very low.

In case of provision of heating by radiation, there is an immediate readiness response, with the elimination of heat inertiae for startup or shutdown.

It is furthermore possible to activate or bypass, in the case of a plurality of coupled radiating panels, one or more panels without imbalances. It should be furthermore pointed out that the content of convection fluid in practice is limited to very modest amounts.

In practice it has thus been observed that the generator-exchanger according to the invention has achieved the intended aim and objects.

The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept.

All the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials employed, so long as compatible with the contingent use, as well as the dimensions, may be any according to the requirements.

Claims

1. Heat generator-exchanger, characterized in that it comprises at least one vacuum pipe bundle containing a substance with convective properties, an end part of said at least one pipe bundle being associated with means for heating said substance, for causing its evaporation and a convective motion thereof, the remainder of said pipe bundle being arranged for exchanging heat with at least one medium.

2. Heat generator-exchanger according to claim 1, characterized in that said at least one vacuum pipe bundle is connected, on the heated side, to at least one tank which contains said substance with convective properties and, on the other side, with at least one unheated tank which is suitable for collecting the condensate and is associated with means for transferring said condensate to the other tank through natural or forced pathways.

3. Heat generator-exchanger according to one or more of the preceding claims, characterized in that the pipes of said bundle are individually executed and are arranged at appropriate mutual distances, constituting individual radiating pipes.

4. Heat generator-exchanger according to one or more of the preceding claims, characterized in that said pipes of said bundle are integrated in a radiating panel at appropriate distances from one another.

5. Heat generator-exchanger according to one or more of the preceding claims, characterized in that said pipes of said bundle are both smooth and finned or otherwise execute .

6. Heat generator-exchanger according to one or more of the preceding claims, characterized in that said substance with convective properties is conveniently water or another substance prepared chemically or not, said substance with convective properties filling the system partially.

7. Heat generator-exchanger according to one or more of the preceding claims, characterized in that said means for heating said substance comprise at least one burner, which uses liquids or solids or gases.

8. Heat generator-exchanger according^'to one or more of the preceding claims, characterized in that said means suitable for heating said substance comprise one or more electric heating resistors.

9. Heat generator-exchanger according to one or more of the preceding claims, characterized in that said burner is appropriately provided with control and safety devices.

10. Heat generator-exchanger according to one or more of the preceding claims, characterized in that the direct exchange of heat with an enclosed space occurs by means of radiating panels which are associated with said pipe bundle or are integrated therewith.

11. Heat generator-exchanger according to one or more of the preceding claims, characterized in that the indirect exchange of heat with an enclosed space occurs by means of forced or natural ventilation.

12. Heat generator-exchanger according to one or more of the preceding claims, characterized in that it comprises a trap system or systems for the air and for the incondensables.

13. Heat generator-exchanger according to one or more of the preceding claims, characterized in that the internal surfaces of said heated tank have means for facilitating the nucleation of the vapor.

14. Heat generator-exchanger according to one or more of the preceding claims, characterized in that it contains substances or treatments suitable for facilitating the ability of the exchange surfaces to be subjected to wetting.

15. Heat generator-exchanger according to one or more of the preceding claims, characterized, in that it has devices suitable for eliminating any presence or trace of hydrogen in the system.

16. Heat generator-exchanger according to one or more of the preceding claims, characterized in that it comprises control devices with both temperature- and pressure-based action.