GB2173123A

GB2173123A - Catalytic heating apparatus for motor vehicle interiors and boat cabins in particular

Info

Publication number: GB2173123A
Application number: GB08606606A
Authority: GB
Inventors: Louis Alix Vezzoli
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-03-19
Filing date: 1986-03-18
Publication date: 1986-10-08
Also published as: FR2579302A1; DE3609258A1; FR2579302B1; GB2173123B; IT8521156V0; GB8606606D0

Abstract

Catalytic heating apparatus comprises a combustion chamber 11 of which one side or wall is a catalytic panel 12. Air to be heated is passed through an externally finned heat exchanger mounted in the combustion chamber 11 and which is contacted externally by the combustion products. The catalytic surface layer of said catalytic panel 12 is placed directly adjacent a wall of a casing which delimits the combustion chamber, without the interposition of the usual layer of thermally insulating material. Furthermore the entire combustion chamber 11 is contained in an insulating envelope or mantle 10 forming an air space into which is passed the air to be preheated by the heat radiated from the walls of the combustion chamber. <IMAGE>

Description

SPECIFICATION Catalytic heating apparatus for motor vehicle interiors and boat cabins in particular The present invention relates to a catalytic heating apparatus in particularforthe interiors of motor vehicles, the cabins of lorries and boats and similar applications.

Catalytic gas heating apparatuses in which combustion takes place in the presence of a catalytic panel in a complete and flameless manner are known and widespread.

In particular the applicant has in the past conceived and built heating apparatuses useful especially for the interiors of motor vehicles consisting basically of a combustion chamber containing a catalytic panel of a type known in itself, a duct for supply of the gas to be burnt, preferably propane or liquid petroleum gas, and a heat exchanger to the interior of which is fed by forced circulation the air and/or water to be heated by the heat produced by combustion.

In heating apparatuses of the previous type in the heat exchanger there are provided holes for the capillary and predetermined distribution of combustion-support air to the combustion chamber, in particular to surface zones of the catalytic panel which furthermore is brought to full operating temperature by an electrical resistance embedded in said panel.

Consequently during the starting stage the electrical resistance is energized to bring the catalytic panel to the appropriate and desired temperature while during the slowest or waiting stage of operation it is sufficient to maintain combustion in a small and circumscribed area of the catalytic panel.

Heretofore operation of the apparatus in question has never been less than satisfactory. However in the field of these heaters there is always a requiremenu to reduce size as much as possible since the available space is quite limited in the interiors of motor vehicles, heavy vehicles in particular.

In the second place, even if as already mentioned the performance of this apparatus is substantially satisfactory a certain quantity of heat produced by combustion is lost due to convection and radiation through the outer walls of the combustion chamber and the wall beneath the catalytic panel.

To obviate this last drawback in known apparatuses there is provided beneath the catalytic layer, which consists of a relatively thin support on which is deposited the catalytic metal or compound, a very thick layer of thermally insulating material such as rock wool.

This clearly causes not negligible and not further reducible minimum dimensions of the catalytic panel and hence in the last analysis of the entire heating apparatus.

The principal object of the present invention is therefore to achieve a catalytic-panel heating apparatus which, while maintaining heating efficiency unchanged would have reduced dimensions and allow recovery of heat which would otherwise be dispersed by convection and radiation through the walls of the combustion chamber.

This object is achieved by a heating apparatus of the type comprising a combustion chamber of which one side or-wall is a catalytic panel of known type, there being mounted in said combustion chamber a preferably finned heat exchanger the exterior of which is immersed in the combustion products while the fluid, in particular air, passes therein under pressure to be heated, first means of supplying gas for burning and second means of supplying combustion-supporting air, characterized in that beneath said catalytic layer is placed directly the wall which delimits the combustion chamber without interposition of the layer of thermally insulating material and in that the entire combustion chamber is contained in an insulating envelope through which passes air to be preheated by the heat radiated from the combustion chamber walls.

In the preferred embodiment of the heating apparatus in accordance with the invention the air preheated in the heat recovery mantle is the same as that which is conveyed into the main heat exchanger contained in the combustion chamber.

In accordance with another feature of the present invention the flue gas, once having exhausted its function of yielding heat to said main heat exchanger, is conveyed to pass over the engine of the motor vehicle or boat, in particular the parts of the motor which require preheating to facilitate starting said engine when it is cold.

In accordance with another feature of the present invention the electrical resistance for preheating of the catalytic panel is replaced by one or more glow plugs of the well-known diesel-engine starting type, in this manner shortening the time necessary to bring the catalytic panel to starting temperature and thus start operation of the heating apparatus.

These and other features and advantages of the present invention will appear more clearly from the detailed description given below in relation to the annexed drawings in which: Figure lisa schematic top and longitudinal sectional view of the heating apparatus in accordance with the invention, and Figure 2 is a schematic cross sectional view of the apparatus of Figure 1.

With reference to the drawings the heating apparatus in accordance with the invention comprises an envelope 10 inside of which is mounted the combustion chamber 11 one wall of which is described by the catalytic panel indicated in its entirety by reference number 12.

The catalytic panel 12 is the conventional type, for example like those produced and sold under the name Termcat of Industrie Engerbhard S.p.A., and comprises a support for example of non-woven glass fabric or other similar material impregnated with the catalytic metal or compound. The support is in turn mounted on a supporting panel which in this case constitutes a side wall of the combustion chamber.

Differently from conventional construction howeverthere is no insulating layer, e.g. of rock wool, between the catalyzer support and the panel, so that thickness is reduced to values on the order of one-fifth of that of conventional catalytic panels.

In the combustion chamber 11 is mounted a heat exchanger 13 having external finning 14 and an internal tube nest 15 through which passes the air to be heated. Said air is conveyed to the inside of the tube nest by a blower 16 and reaches the upstream end of the exchanger 13 in a head manifold 17 which communicates with a duct 18 which exhausts the hot air into the enclosure to be heated under the control ofavalve 19.

Discharge of the flue gas produced in the combustion chamber 11 takes place through an exhaust manifold 20, the downstream end of which can be extended (e.g. by means of a flexible tube) to the engine compartment for preheating of the engine.

As can be readily seen from Figure 1 the air enters the mantle or envelope 10 through the peripheral opening 21, moving in the direction of the arrows 22 so that it passes over the outer walls of the combustion chamber, being preheated by the heat radiated from said walls.

At the other end of the envelope 10 the preheated air is sucked in by the blower 16 and fed into the tube nest of the exchanger 13 in which it is heated to the desired temperature by the heat developed by combustion.

It is however possible and foreseeable to use differently the preheated air in the space existing between the envelope 10 and the combustion chamber11.

As regards the flue gas exhausted through the manifold 20 it is possible to increase the speed and pressure thereof by taking a portion of the air issuing from the exchanger 13 heated and under pressure, e.g. by providing an ejector at the inlet of the exhaust manifold 20.

It is worthy of note that the air which is heated is always under higher pressure than the flue gas so that return of said flue gas and mixing thereof with the hot air exhausted through the exhaust duct 18 is impossible.

Concerning the last feature noted above, i.e.

replacement of the catalytic panel prelighting resist ante with glow plugs, suffice itto remark that said replacement is accomplished without the necessity offurther details in a detailed graphic representation.

The invention has been described in relation to a preferred embodiment, it being understood that conceptually and mechanically equivalent modifictions and variants are possible and foreseeable without exceeding the scope of the invention.

Claims

1. Catalytic heating apparatus of the type comprising a combustion chamber of which one side or wall is a catalytic panel known in itself, a heat exchanger finned externally mounted in said combustion chamber in such a manner as to be licked externally by the combustion products while inside thereof passes the fluid to be heated, first means of feeding combustible gas and second means of feeding combustion-supporting air characterized in that beneath the catalytic surface layer of said catalytic panel is placed directly the wall which delimits the combustion chamber without the interposition of the usual layer of thermally insulating material and in that the entire combustion chamber is contained in an insulating envelope or mantle forming an air space into which is passed the air to be preheated by the heat radiated from the walls of the combustion chamber.

2. Catalytic heating apparatus in accordance with claim 1 characterized in that said fluid to be heated in said exchanger is air and in said envelope or mantle there is mounted a blower for feeding of said airto the interior of said exchanger, suction of said ventilator being arranged in such a manner as to suck said preheated air into said airspace.

3. Catalytic heating apparatus in accordance with claim 1 characterized in that said combustion chamber communicates with an exhaust manifold for the flue gas, the downstream end of said manifold being in communication with the engine compartment ofthe vehicle or boat.

4. Catalytic heating apparatus in accordance with claim 3 characterized in that said exhaust manifold for flue gas is in communication with the outlet of an ejector fed by a portion of the heated air issuing from said exchanger.

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5. Catalytic heating apparatus in accordance with claim 1 characterized in that said catalytic panel has at least one electrically fed glow plug as a means of preheating said panel.

6; Catalytic heating apparatus substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

7. Any novel feature or combination of features described herein.