GB2030695A - Heating system - Google Patents

Abstract

A heating system comprises a conduit system, and means (e.g. a pump or fan 3) for circulating a heat carrying fluid (e.g. gas or liquid) in the conduit system, wherein part of the conduit system (e.g. series-connected conduits 2a, 2b, 2c, 2d) is built-in in a covering 1 to be heated or surrounding a space or object to be heated, and wherein the conduit system extends through the covering 1 in such a manner that the heat carrying fluid emits heat at progressively decreasing temperatures from the warmer side 1a to the colder side 1b of the covering. The covering may e.g. comprise a wall, road, platform or runway. The system may alternative comprise a heat pump system (e.g. Figs. 2, 3) wherein means are provided for compressing said fluid (e.g. in a compressor 6), before entering said built-in part of the conduit system and for expanding the fluid (e.g. in units 7 or 7' or 7'') after it has passed said part. Heat energy can be supplied to the system from means including a combustion unit 4, and/or low temperature heat energy accumulator(s) 5, and/or a solar-heat collector (8, Fig. 2). <IMAGE>

Description

SPECIFICATION Heating system The present invention relates to an improved heating system of the type using a heat carrying fluid circulating in a conduit system.

It is an object of the present invention to provide a simple and energy saving system for heating coverings, which are preferably heat insulated and across which there is a temperature difference, such as house walls and other coverings surrounding a space or an object to be heated.

Another object of the invention is to provide a system for efficient utilization of low temperature energy for heating purposes.

A further object of the invention is to provide a modified heat pumping system, which can be used for heating purposes without requiring complex heat exchange devices.

Still another object of the invention is to provide a combined heating and energy conversion system in which low temperature heat energy can be converted into useful mechanical and/or electrical energy.

In previously known heating systems such as the one disclosed in my published Swedish patent application No. 7600427-4, low temperature heat energy stored in ground accumulators is utilized.

In said system a heat pump is used for converting the low temperature energy of the accumulator into useful high temperature energy which is used for heating rooms and the like by means of conventional heating systems. Furthermore, said system utilizes low temperature energy from the ground accumulator for circulating a heat carrying fluid in a circulation system arranged within said outer covering to form a "climate cage" in the outer and cooler portion of the covering. This known system has proved to operate excellently, but it requires a conventional heat pump and is also best suited for using a liquid in the conduits for the energy transports. It would be desirable to be able to use air as the energy transporting medium, for example for the heat pumping.

However, the necessary heat exchange devices are expensive and bulky, especially because of the low heat content and the limited thermal conductivity of the air. This is disadvantageous at the small temperature differences aimed at, since it is not either possible to utilize phase changes between liquid form and gas form.

According to the invention the above mentioned properties of air have instead been turned to be advantageous. This has, among other things, been made possible by means of now available types of thin walled-and cheap plastic tubes standing the necessary pressures. The invention requires a new principle for the construction of walls and the like, viz. to build in a heat emitting conduit system having comparatively large surfaces of series and parallel connected sections into the walls and other parts of the outer covering of a building or the like.

According to a first aspect of the invention there is thus provided a heating system comprising a conduit system, means for circulating a heat carrying fluid in the conduit system, and means for heating the heat carrying fluid. According to the invention the system has a part thereof built in into the covering surrounding the space or object to be heated. The built-in part of the conduit system preferably comprises a plurality of series connected sections arranged at varying distances from the outer surfaces of the covering. The heat carrying fluid is introduced into the covering from the warmer side thereof (i.e.

from the side facing the space or object to be heated), and the heat carrying fluid progressively emits heat energy to the surrounding covering at progressively decreasing temperatures as the fluid approaches the colder side of the covering.

According to another aspect of the invention there is provided a heating system of the above indicated type, which is arranged to operate as a big heat pump. To this end the system is provided with compressor means for compressing the hect carrying fluid before the same emits heat at a higher temperature, and further with an expansion device for expanding said fluid when it has fulfilled its heating function.In this case the built-in conduit system in the outer covering can be regarded as corresponding to the condenser in a conventional heat pumping device, whereas the evaporator cf a conventional heat pumping device is substituted by an accumulator for storing low temperature heat energy, preferably a ground accumulator, which is arranged to transfer heat to the heat carrying fluid before the same enters the compressor means.

Because of this design of the system according to the invention the need for complex heat exchange devices is eliminated to a great extent, offering the advantages of an uncomplicated design and a very high heat factor. Furthermore, the expansion work can be utilized efficiently, and according to a further aspect of the invention the expansion work is utilized for the production of electrical or mechanical energy.

In the system according to the invention the heat carrying fluid is preferably air or another suitable gas, but the basic principle can also - with minor modifications -- be applied to completely or partly liquid carrying systems. With air and/or a liquid as the heat carrying fluid the system can be used not only for room heating, but also for other purposes such as ground, road and platform heating or energy saving control of the temperature of landing runways for aeroplanes, and the like, the arrangement, location and design of the built-in conduit system ("the condenser") being adapted to the needs and requirements in the specific situation.

These and other objects and characteristics of the invention appear from the following description of preferred but non-limiting embodiments of the invention. Reference is made to the enclosed drawings, in which Fig. 1 schematically illustrates a first embodiment of the heating system according to the invention, Fig. 2 schematically illustrates a second embodiment of the heating system according to the invention, arranged for simultaneous energy conversion, and Fig. 3 illustrates an alternative embodiment of the system illustrated in Fig. 2.

In Fig. 1 there is shown an outer covering 1 such as a house wall surrounding a space to be heated, the warmer side of the covering (i.e. the side facing the space or object to be heated) being designated 1 a and the colder outer side of the covering being designated 1 b. A conduit system 2 in which a heat carrying fluid circulates extends through the outer covering 1. The conduit or tubing system 2 has a plurality of sections 2a, 2b, 2c, 2d, which are built-in in the outer covering at varying distances from tlle outer surfaces 1a, 1b thereof.All of said sections 2a-2d are preferably arranged substantially parallel to the outer surfaces 1a, 1 b of the outer covering 1.The essentially parallel conduit sections are series connected by means of suitable connecting portions 2e. (All of the sections 2a-2d may, of course, be integrai and formed of e.g. a bent plastic tube.) Each section 2a-2d preferably comprises a plurality of parallel connected parts, which are arranged at suitable intervals along the outer covering 1.Outside the outer covering 1 the conduit system 2 forms a closed cycle including, on the one hand, a circulation device 3 such as a pump or fan for circulating the heat carrying medium through the conduit system, and, on the other hand, a heating device 4 for heating the heat carrying fluid before the same is fed into the conduit section 2a. After having delivered heat to the outer covering 1 the heat carrying fluid is - in the illustrated embodiment-- allowed to pass through a low temperature heat energy accumulator 5 such as a ground accumulator for absorbing low temperature heat energy from the same.

The heating system illustrated in Fig. 1 operates in the following manner The circulation device 3 forces the heat carrying fluid to pass through the system in the direction of the arrows.

The fluid is heated when passing through the heating device 4, and then enters into the outer covering to the conduit section 2a located closest to the outer surface 1 a. The fluid then in turn passes the conduit sections 2b, 2c and 2d and then leaves the outer covering. The heat carrying fluid thus has the highest temperature when it passes the sectiori 2a, and in this section the fluid emits heat to the outer covering at a comparatively high temperature. As the fluid passes through the subsequent sections the temperature thereof decreases. However, also the temperature of the surrounding covering decreases, and the fluid is capable at emitting heat energy to the outer covering also in the sections 2b, 2c and 2d, although at decreasing temperatures. In this manner it is possible to utilize a maxlmum of the heat content of the heat carrying fluid.The fluid escaping from the section 2d is thus comparatively cold, and it is preferred to have tlie same pass though th low temperature heat energy accumulator 5 and be heat exchanged against the same, whereby pre-heating of the fluid takes place using cheap low temperature heat energy. The fluid is then again allowed to pass through the heating device 4, where the final temperature before the entrance into the outer covering 1 is determined. The circulation velocity and the heating intensity in the device 4 is preferably controlled in a conventional manner by means of thermostates (not shown). It should in this connection by noticed, that the advantages offered by the sections 2a-2d would be obtained also without using the ground accumulator 5, i.e.

with the heat carrying fluid being passed into the heating device 4 directly after having escaped from the outer covering 1 via the coldest conduit section 2d.

In the embodiment illustrated in Fig. 2 the system according to the invention functions as a modified heat pumping device, which in a conventional manner comprises a compressor 6 and an expansion device 7. In place of a conventional condenser the system is provided with a conduit system 2, which is built-in in the outer covering 1 and comprises a plurality of sections 2a-2d in the same manner as in Fig. 1 (If operating- with an open system, e.g. after the expansion device, the system can also be viewed as a cold air machine.) Furthermore, in place of the evaporator of a conventional heat pumping device the heating system according to the invention has an accumulator 5 for storing low temperature heat energy, e.g. a ground accumulator of the type described in my published Swedish patent application No. 7600427-4.The heat carrying fluid flowing through the system can be supplied with energy in different ways, e.g. by means of solar collectors 8 and/or accumulators 5 and/or heating devices 4, such as firing devices 4 for wood chips or other fuels.

The above described system can, for example, be operated in the following way. When air is used as the heat carrying fluid the air is compressed by means of the compressor device 6 to raise the temperature in the pressure conduit system 2 immediately after the compressor device 6 to about +250C, in the case of housing heating (when using air the necessary pressure increase is only about 0.2 to 0.3 atm). In the tubing section 2a closest to the inside 1 a of the outer covering 1 said section serving as a heat element for the space (or object or the like) to be heated-the desired room temperature is maintained (heating function).

Because of the transmission losses the temperature then decreases continuously in the pressure conduit system 2b, 2c, 2d and approaches the temperature of the ambient air in the tubing 2d closest to the outer side 1 b of the outer covering 1. When the system is correctly adjusted the temperature in each tubing section 2a, 2b, 2c, 2d is so much higher than the corresponding temperature would be without tubing or conduits in the wall (at an inner temperature of +200C) that each tubing section emits equally much energy.In conventional systems the air has to give off the heat between, for example, +300C and +200 C, causing air streams in the spaces to be heated, but in the system according to the invention the air is allowed to give off its heat contents progressively between, for example, +250C and down to about -250C, meaning that up to more than five times as much energy can be taken off from the same amount of air. Furthermore, this is achieved by indirect heating and at a lower heating temperature. The dimensions of the compressor device 6 can consequently be reduced, and the characteristics of the heat emission inside the outer covering 1 is very well suited for air as the heat carrying medium.

After the air has delivered a maximum of energy at a maintained pressure and left the covering 1 it is passed into the expansion device 7 and allowed to expand in the same. After the expansion work and the pressure decrease the air temperature decreases considerably.

The pressure conduit is preferably designed as a cooler in front of escaping air, causing a recoupling with a progressive decrease of temperature to a very low balance value so that the expansion work is further increased. This work can be greater than the work (including losses) supplied for operating the compressor device 6, if the air is sufficiently prehheated. The device can then be used not only for heating purposes, but also for converting heat energy into e.g. electrical power. The compressor device 6 is then preferabl) driven by a motor M, such as an induction motor, which at the same time can function as a generator G, driven by the expansion device 7 on the same axis. Supply of energy and preheating can be achieved in many different ways, e.g. by means of solar energy via solar collectors 8 and/or the accumulator 5.

Further heating of the air can be motivated for increasing the generator effect. This can be achieved by using a heating device 4 such a device for firing wood chops or other fuels, and this device can also be used for providing hot tap water. In the embodiment illustrated in Fig. 2 the firing device 4 has been arranged before the compressor device 6, but it can as an alternative be located in other places in the system. The compressor device 6 can be replaced by one or more pressure increasing fans, one of which preferably can be arranged after the expansion device 7, among other things for serving as a check valve for the pressure and volume increase occuring because of the heating in the accumulator 5.

The above description has referred to a heating device having a conduit system 2 consisting of simple tubes. In order to, among other things, facilitate controlled heat regulation in the outer covering 1 and at the same time provide for a more uniform heat absorbtion from the accumulator 5 to the tubes, which are always coldest when entering the accumulator 5, the tubing system can be built-up as a double tubing system 2+2', a heat carrying fluid of normally low and controlled velocity flowing in the space between the inner tubing system 2 and the outer tubing system 2'. This fluid flows (see the arrows B) in a direction opposite to the direction of the heat carrying fluid in the inner tubing system 2 (see the arrows A).The heat carrying fluid in the outer conduit system 2' can be a separate fluid, which is circulated by means of separate fans, pumps or the like, but in the illustrated embodiment the same fluid is used in both of the systems. In this embodiment an adjustable valve 9 is provided on the pressure side of the compressor 6, whereas an inlet 10 is provided on the suction side of the compressor 6. The double tubing 2, 2' and the counter stream principle mean that a considerable part of the transmission losses in the covering 1 are replaced by energy from the accumulator 5, implying that the dimensions of the machinery can be reduced further.

The embodiment illustrated in Fig. 3 comprises the same basic components as the embodiment according to Fig. 2, i.e. the accumulator 5, the "condenser" sections2a-2d built-in in the covering 1, the compressor 6 etc., whereas the manner in which the expansion work is utilized differs between the two embodiments.

In the embodiment according to Fig. 3 the expansion means essentially consist of two similarly designed units 7' and 7" respectively.

Each such unit is designed as a "bottomless" container (which for example can be placed directly on the ground) having double walls 10 and 11 respectively. The space between said walls is filled with a liquid 12 such as oil or a refrigerant liquid serving as a sealing for a gas dome 13', 13" floating in the sealing liquid 12. A lever 1 6 is connected between the two gas domes 13', 13", and it is pivotallyjournalled on a central axis 17.

By means of the lever 16 pressure energy is converted into kinetic energy as explained below.

(In place of the illustrated gas dome structure any other suitable expansion chamber device can be used, the volume of which can be increased and decreased in response to pressure variations within the chamber and which in this manner can provide a work. For example, well known piston/cylinder assemblies, bellows and the like can be used.) The tubing sections 2a-2d, corresponding to the condenser in a conventional heat pumping device, are in this embodiment completed with two containers 18' and 1 8". The containers 18' and 18" are connected to the tubing sections 2a2d by means of a valve 19, which is adjustable so as to connect either the first or the second of the containers 18' and 18" with the tubing sections 2a-2d. Each container 18', 18" is via a suitable throttle valve (or expansion valve) 20', 20" connected with the expansion chambers 14' and 14" respectively of the expansion units 7' and 7". The expansion chambers 14' and 15" are also connected to the low side (suction side) of the compressor 6 by means of branch conduits 21' and 21" respectively. A valve 22, which is adjustable as described below, is provided at the point of connection.

The above described device operates in the following way: In the position shown the gas dome 13" has just passed its highest position (and the dome 13' thus its lowest position). In this position suitable sensing means (not shown) switch the valves 1 9 and 22 to a position in which the heat carrying fluid flows as indicated by the continuous arrows. The compressor 6 is drawing air from the expansion chamber 14" by means of the conduit 21" and compresses the air in the tubing sections 2a-2d and the container 1 8".

When the compressed air passes through the throttle valve 20" it expands into the expansion chamber 14 with decrease of the temperature (in addition to the decrease of temperature occurring inside the covering 1). As a consequence the pressure in the chamber 14" decreases progressively, creating a suction force moving the dome 13" downwardly. Because of the progressive decrease of the temperature at a maintained pressure from the compressor 6 a maximum amount of air will be packed in the sections 2a-2d and the container 1 8" (without additional supply of energy) until the dome 1 3" has reached its bottom position, i.e. the same position as the gas dome 13' occupies in Fig. 3. In the bottom position for the dome 13" the valves 19 and 22 are again actuated to cause the heat carrying fluid in the system to flow as indicated by the dashed arrows.Thus, the valve 1 9 closes the connection between the compressor 6 and the container 18", but air continues to flow out through the throttle valve 20" because of the overpressure in the container 4, resulting in an increase of the gas volume in the expansion chamber 14" and of the pressure on the gas dome 13" until a pressure balance has occurred between the container 18" and the remainder of the system. At the same time heating of the very cold air in the chamber 14" is started, as the switching of the valve 22 creates a circulation path between the expansion chamber 13" and the accumulator 5, by means of the conduits 23", 2 and 21". This circulation is obtained by means of a fan 24.Low temperature heat energy is absorbed from the accumulator 5 and the resulting raise of the temperature of the circulating medium causes the increase of the gas volume in the chamber 14" to continue with continued pressure on the dome 13" until the latter has reached its upper end position, in which the valves 1 9 and 22 again change the flow direction of the heat carrying fluid to the path indicated by the continuous arrows.

The work performed by the up and down movements of the domes 13' and 13", with pic otation of the lever 16 around its fulcrum 17 can be used directly or indirectly for conversion into the desired energy form such as electrical energy by suitable means, as is well known in the art.

The described system can be designed with an optional number of gas domes 13', 13" or the like and be arranged for desired stroke lengths, working pressures and dimensions. The efficiency of the system can be further increased by supplying heat energy to the system by means of the firing device 4.

It should in this connection be underlined that the heating of the covering 1 takes place in the same manner as decribed in connection with the embodiment according to Fig. 2. In the present embodiment absorption of heat, further temperature decrease by expansion as well as pressure and temperature increase by means of low temperature heat energy from the accumulators 5 cooperate in making it possible to convert a maximum amount of energy from a low temperature accumulator into heat energy suitable for heating purposes and, if desired, to mechanical work, which can be converted into the desired form of energy by means of conventional methods and means.

The invention is not limited to the embodiments described and illustrated in the drawings, but many modificattons and variations are possible within the general scope of the invention.

Claims (11)

1. A system for heating spaces and objects surrounded by an outer covering as well as such coverings, wherein the heating takes place by circulation of a heat carrying fluid in a conduit system, a part of which system is built-in in the outer covering and extends therethrough in such a manner that the heat carrying fluid emits heat at decreasing temperatures from the warmer side to the colder side of the outer covering.

2. A heating system according to claim 1, wherein the conduit system comprises a plurality of series connected sections which are located at varying distances from the outer surfaces of the outer covering.

3. A heating system according to claim 2, wherein each of said sections comprises a plurality of parallel connected conduits which are spaced apart and arranged at essentially the same distance from the outer surfaces of the outer covering.

4. A heating system according to claim 1,2, or 3, wherein it includes a device for heating the heat carrying fluid before the entrance thereof into the outer covering at the warmest side thereof.

5. A heating system according to claim 1, 2, 3, or 4, wherein said conduit system is a closed system.

6. A heating system according to claim 1, 2, 3, 4, or 5, wherein an accumulator for storing low temperature heat energy is included, and said conduit system is arranged in heat exchanging contact with the accumulator downstream of said outer covering.

7. A heating system according to any one of claims 1 to 6, with a heat pumping device having compressor means and expansion means and further having said built-in conduit sections in place of conventional condenser means, and an accumulator for low temperature heat energy in place of conventional evaporator means, the system possibly also having means for preheating the heat carrying fluid before the entrance thereof into the compressor means.

8. A heating system according to claim 7, including means for conversion of the expansion work of the expansion means into mechanical or electrical energy.

9. A heating system according to claim 8, wherein said compressor means are arranged to be driven by an electrical motor which is arranged to also be driven as a generator by the expansion work of the expansion means.

10. A heating system according to claim 8, in which the expansion means comprise at least two expansion chambers in which said heat carrying fluid is brought to expand, each such chamber comprising a portion movable in response to the pressure in the chamber, in that downstream portions of said built-in conduit sections are arranged to be alternatingly connected to first and second containers, each of said containers communicating by means of throttle valves with the respective expansion chamber for expansion of the compressed heat carrying fluid, in that conduits and switchable valves are arranged to form a first closed cycle comprising said condenser means, said conduit sections, one of said containers and one of said expansion chambers, and at the same time a second closed cycle, by which the second of said expansion chambers is supplied with heat from an accumulator for low temperature heat energy, and, if desired, also from an extra heating device, in that switch means are arranged to connect the expansion chambers alternatingly to said first and second closed cycle when the pressure in the first chamber has reached a maximum value and the pressure in the second chamber a minimum value, and in that means are arranged to convert the expansion work of the expansion chambers into a useful energy form.

11. A system for heating spaces and objects surrounded by an outer covering as well as such coverings, substantially as hereinbefore described with reference to the accompanying drawings.