FR2488682A1 - Closed-circuit solar heating system - has collector panel for extraction of high and low-grade ambient heat - Google Patents

Abstract

A first heat exchanger (10) in the form of a solar panel is located outdoors to absorb both direct solar energy and non-solar energy and thereby heat a volatile fluid passing through. A second (indoor) heat exchanger (30) is connected to heat another fluid such as air or water. Separate pipes connect the elements of the system into a closed circuit for a volatile refrigerant fluid which is continuously circulated. An expansion valve (40) is located in the system closer to a compressor (20) than to the first heat exchanger. The conduits (11,42) which deliver volatile fluid to and from the first heat exchanger have portions (11a,42a) positioned close to each other to provide for heat transfer.

Description

 The present invention relates to domestic heating systems or the like and, more particularly, solar heating systems using a volatile refrigerant which passes in a continuous cycle of an external heat exchanger, that is to say located at outside a building, to an internal heat exchanger, for example inside the building, the volatile fluid acting to transfer both "high level" (non-solar) heat and (non-solar) heat " low level "absorbed by the external heat exchanger, to the internal heat exchanger for use in heating.

 It is well known to produce heating systems using volatile fluids which circulate in closed loop circuits and which include heat exchangers located outside to transfer both "low level" heat (heat which is associated with moving air or heat radiated by the ground, by plant life or animal life, etc.) and "high level" heat (heat which is generated by the sun's rays) to heat exchangers located inside the buildings for heating.

 For example, in the U.S. patent

 No. 2.529.154, a heating system is exposed which can transfer both low level heat and high level heat from the outside of a building to a heating coil located inside the building. However, this system uses three separate closed fluid circulation circuits, two of which have at least parts extending outside the building to be heated. The first circuit (which is the main circuit) includes a compressor, a condenser (exchanger heat) and an expansion valve and the piping that connects these elements together includes a part between the expansion valve and the compressor, which is buried in the ground outside the building to be heated, A volatile refrigerant ( chlorofluorocarbon or fluorocarbon) circulates in this first circuit and acts to transfer heat from the ground outside the roof to the condenser located inside the building.The second circuit comprises an endless pipe in which the water circulates, the pipe comprising a first coiled part located inside said condenser and a second coiled part located outside the condenser and inside the building, the water being heated into the condenser and then passing into the coiled part located inside the condenser, so as to heat the air inside the building. The third circuit comprises an endless pipe comprising a first part wound on the roof of the building (heat absorbing part) and a second part buried in the ground in the vicinity of the buried part of the pipe of the first circuit. A fluid such as water circulates in the third circuit and acts to transfer the heat communicated to it by the sun (while the water passes through the heat absorbing part of the third circuit on the roof) to the ground and thus helps to heat the refrigerant passing through the first circuit.

 Although it could be said that this prior art heating system advantageously uses both the high level heat from the outside and the low level heat to heat the interior of a building, in fact what The system is very complicated, since a total of three circulating fluid circuits are provided, and it is also difficult to build, since this requires the burial in the ground of significant parts of two piping circuits next to the building.

In US Patent No. 2,689,090, a similar system is described, which also has similar disadvantages,
In US Patent 3,991,938, a fairly different heating system is exposed. In this system, capable of heating the interior of a building both by high level heat and by low level heat found outside the building, two heating circuits are used. circulating fluid comprising parts located outside the building.

The first fluid circuit uses water flowing through an open and tilted solar absorber, which is located on the roof of a building. Water is sprayed against the upper surface of a flat plate located at the upper end of the solar absorber and after first being frozen in it, then melted so as to descend through the solar absorber , it is extracted from the lower end. The water is then brought to circulate by pipes through a first radiator (heat exchanger) located inside the esteem in a condenser (in which it is heated by the condensation inside its of a volatile fluid ), then goes through a second radiator (heat exchanger) located inside the bttmsent and then returns to the upper end of the solar absorber. In the second fluid circuit, a volatile fluid passes through an evaporator tube located below the flat plate of the solar absorber (so as to periodically freeze the water sprayed on its upper surface), then it circulates through a pipe in a compressor, passes through the condenser and a flow restrictor and finally returns to the evaporator tube. A valve, suitably placed in the second fluid circuit, makes the volatile fluid pass only intermittently through the tubes evaporators, thereby intermittently freezing the water that is sprayed onto the flat side of the solar absorber, so that frozen water can intermittently absorb both high level heat and heat at a low level when it melts, this heat being transferred by the water circulating in the first fluid circuit to the radiators inside the building.

 This system has many drawbacks and in particular that other complicated and cite, especially since it includes two fluid flow circuits having parts located outside of a building.

 The object of the present invention is in particular to allow the construction of a simple and economical yet efficient heating system which can absorb both the high level heat (solar) and the low level heat (solar name) of the exterior of a building and efficiently transfer it inside the building to be used for heating the system comprising the use of two fluids which only passes through a circulation circuit which comprises a part situated outside the The object of the invention is also to construct such a heating system which can operate efficiently, even if its external heat exchanger is subjected to extreme temperature differences, that is to say in the case where it operates in climates such as the temperature differences between summer and winter are considerable.

 According to the present invention, the heating system comprises a closed circulation circuit including an external heat exchanger (solar panel) intended to be placed outside a building so as to collect the sun's rays in sunny weather, the external heat exchanger being constructed so as to efficiently absorb both the low level heat and (particularly) the high level heat, a compressor, an internal heat exchanger intended to be placed inside the 'a building to be heated and an expansion valve, the cited elements being interconnected by pipes so as to form a closed circulation circuit in which circulates a volatile refrigerant. Volatile refrigerant flows from the external heat exchanger to the compressor, then passes through the internal heat exchanger, then through the expansion valve and finally returns to the external heat exchanger, suitably changing its characteristics (" its state ") during heat transfer from the external heat exchanger to the internal heat exchanger (as in the basic reverse cycle refrigeration technique).

 The external heat exchanger used in 1. system according to the invention will be "closed", so as to prevent the escape of the volatile fluid passing through it and it is advantageously constructed so as to have a large contact surface between the channels d 'flow inside which are exposed to the surrounding atmosphere and to the volatile fluid which crosses it.

According to one embodiment of the invention, the external heat exchanger will include a support panel on which a metal tube is supported, being curved so as to define a circumvented or serpentine circulation path for the volatile fluid which passes there and thus obtaining maximum exposure of the volatile fluid to the heat absorbed by the tube. In another embodiment, which is preferable, the external heat exchanger can comprise two metal sheets fixed together which together define channels between them. multiple fluid flow, these channels also defining a generally contoured or serpentine path for the volatile fluid flowing. In either embodiment, copper or aluminum constitute the preferred metals for the production of pipes or sheets, since each of these metals is both highly heat conductive and mechanically solid.

It is desirable to apply a dark coating to the surfaces of the metals forming the fluid flow channels in the external heat exchanger to assist in the absorption of heat from the sun by the volatile fluid flowing therein. The external heat exchanger of the invention is thus capable of absorbing heat from the sun as well as heat from the surrounding atmosphere, even at very low ambient air temperatures. n with regard to its absorption of non-solar heat, the heat of the humidity in the air can be absorbed when it condenses on the metal surface of the external heat exchanger (the condensed humidity being observable in the form of frost).

 A critical characteristic of the heating system according to the invention which allows it to operate in environments in which the summer-winter temperature differences are large is that the volatile fluid supply pipes leading to the heat exchanger. external heat and extracting the volatile fluid from this changer and which are preferably made of copper have adjacent parts of the external heat exchanger which are placed close enough to one another so as to obtain a heat exchange between them. A preferred technique for achieving this result is to place these parts of the tube in contact along their length. However, other methods can also be used, for example these parts can be placed side by side in a larger conduit. or simply by placing them side by side in the ground or inside the walls of a building.

 A second critical characteristic of the heating system according to the invention is that the expansion valve is placed operatively closer to the compressor than the external heat exchanger. This is achieved by using appropriate lengths of pipe between the various elements of the heating system.

The heating system of the invention will operate with any volatile fluid having an appropriate vapor pressure as well as latent heat of vaporization and suitable specific heat over the operating temperature range of the system; however the preferred volatile fluid is CC12F2
During operation, the volatile fluid which circulates in the heating system of the invention will enter the external heat exchanger (outside) in the form of a liquid-vapor mixture and will be converted to the vapor state by the heat which it is transferred there by passing through the external heat exchanger (outside). The volatile fluid in the vapor state will pass, after having transferred part of its heat to the liquid-vapor mixture entering the external heat exchanger, in the compressor in which its pressure and temperature will be high (the electrical energy necessary to compress the vapor will typically be 30 to 5OYo of the total energy produced by the system), then in the heat exchanger (condenser) internal (interior) od it will be cooled, thereby changing from a vapor state to a liquid state and at the same time transferring the heat energy to another fluid (for example air or water) which is separately pumped through the internal heat exchanger. The volatile fluid, Be then being in the liquid state, will then pass through a gsaee expansion valve to which it will transform into a liquid-vapor mixture.

This mixture, after having absorbed heat borrowed from the volatile fluid in the vapor state leaving the external heat exchanger, then enters the external heat exchanger, so as to traverse a complete cycle of transfer of heat energy in the system.

The main advantages of the heating system of the present invention are that:
(1) Energy is collected from the outside day and night, whether it is sunny or cloudy.

 (2) The system will operate effectively in cold or hot weather and in climates with large temperature differences between summer and winter.

 (3) The external heat exchanger is constructed to operate at temperatures below that of air.

 (4) External heat exchanger will be made of metal; this advantageously avoids the use of glass or plastic panels.

 (5) The gel or the need to drain the external heat exchanger is eliminated.

 (6) The system is practically maintenance-free.

 (7) The system is easily installed and usable with any style of house or bttxment.

 (8) The location (and shape) of the external heat exchanger is not as central as in other heating systems and one can have ornamental facings and decorative or commercial reproductions harmonizing with the interior of the house.

The invention will be better explained and understood by the following presentation of examples of embodiments, with reference to the drawings among which s
Figure 1 is a schematic representation of a system according to the invention;
- Figure 2, the diagram of the recirculation of the fluid transferring heat from a heating system for its final operation;
- Figure 3, a plan view of an external heat exchanger, according to a preferred embodiment, which is used in the heating system of Figure 1;
- Figure 4, an enlarged cross section of the exchanger of Figure 3, along line 4-4 and
- Figure 5, an enlarged cross section of the exchanger of Figure 3, along the line 5-5.

 FIG. 1 shows the basic elements of the heating system of the invention, generally designated by the reference 100. Although it can be seen that the system comprises, as essential constituent elements, an external heat exchanger 10 (placed at outside of the briment so as to be struck by the rays of the sun), a compressor 20, an internal heat exchanger 30 and an expansion valve 40, the preferred system represented in FIG. 1 also comprises an accumulator 13 and a regulator pressure 16 located between the external heat exchanger 10 and the compressor 20; it also includes a dryer 33 and a glazed manhole 36 located between the internal heat exchanger 30 and the expansion valve 40. The various elements are tightly connected to each other by respective pipes 11, 14, 17, 22, 31, 37 and 42 so as to form a single closed circuit loop for the volatile fluid which passes there. The length of the pipe 42 is greater than the added lengths of the pipes 22, 31, 34 and 37, this condition causing the expansion valve 40 to be placed functionally closer to the compressor 20 than to the external heat exchanger 10.

 As can be seen in FIG. 1, the pipe 11 which brings the volatile fluid coming from the external heat exchanger 10 to the accumulator 13 comprises a part 11a, adjacent to the external heat exchanger, which is parallel, with direct contact, to a part 42a of the pipe 42 bringing the volatile fluid which comes from the expansion valve 40 to the external heat exchanger 10. Because of this arrangement, there is an exchange of heat of the volatile fluid which circulates in these pipe parts (the heat will pass from the volatile fluid circulating in the pipe part 11a to the volatile fluid passing through the pipe part 42a, because of the higher calorific content) and thus the volatile fluid circulating in the pipe part 42a will undergo varying degrees of phase change before entering the external heat exchanger (this effect being maximum when the external heat exchanger absorbs large amounts of energy, for example when predominant conditions ons correct so that it absorbs large amounts of solar radiation). After passing through the accumulator 13, the volatile fluid passes through the pressure regulator 16 which acts to prevent damage to the compressor 20 in the event that the pressure of the volatile fluid is exaggerated, then goes to the internal heat exchanger 30.

 In the internal heat exchanger 30 the heat contained in the volatile fluid is transferred to another fluid, for example water, which can be circulated for operation in the separate circulation system shown in the FIG. 2. In this separate circulation circuit, the water which has been heated in the internal heat exchanger 30 passes through a check valve 50 and can be directed, thanks to a three-way tap 55, ie to circulate by means of a pump 57, in a heating coil 70 (provided with a vent 71) placed in a suitable place to heat the air of a room, then brought back into the internal heat exchanger 30, that is to say brought to a hot water tank 60 used for household needs. An aquastat (thermostat for adjusting the water temperature), 72 and a thermostat 73 can be used to coordinate the operation of the circulating water system and the demand for heating of the hot water tank and / or the -heating room.

 The cooled volatile fluid then flows from the internal heat exchanger, passing through a dryer 33 which is used to extract foreign matter and / or the humidity of the volatile fluid and through a manhole 36 which makes it possible to determine if the load of the system is suitable and to detect the presence of air bubbles, as well as by the expansion valve 40 and up to the external heat exchanger. The degree of expansion of the volatile fluid obtained by the valve 40 can be controlled by means of measuring the temperature and the pressure, 40a and 40b, placed against the pipe 11.

 The external heat exchanger 10 used in the heating system 100 is preferably constructed as seen in FIGS. 3 to 5 in order to obtain maximum external heat exchange for the volatile fluid which passes through it. In this embodiment two shaped metal sheets 80 and 81 are welded together so as to form between them a closed fluid circuit allowing the circulation of a volatile fluid which goes from an inlet opening 10a to an outlet opening 10b. This closed circuit will cause the fluid to flow, in general, in a wavy fashion (see the indication of this flow in phantom, in FIG. 1).

The two metal sheets have the same shape and contour, as can be seen in FIGS. 4 and 5, so as to constitute a first mixing zone 83, a pre-cutesy zone of parallel passages 84, a first crossing zone 85, a second parallel passage zone 86, a second mixing zone 87, a third parallel passage zone 88, a second crossing zone 89, a fourth parallel passage zone 90, a third mixing zone 91, a fifth parallel passage zone - 92, a third crossing zone 93, a sixth parallel passage zone 94, a fourth mixing zone 95, a seventh parallel passage zone 96, a fourth crossing zone 97, an eighth parallel passage zone 98 and a fifth zone (final) of mixing 99. The first mixing zone 83 has, overall, a triangular shape, being formed between the sides of the corner and the end portions of the metal sheets 80 and 81 glued together , as well as the ends of the recesses forming the first zone of parallel passages 84 and includes multiple triangular columns also formed by recesses connected together from sheets 80 and 81, which act to mix the volatile fluid as it passes there. parallel passage zone 84, formed by recesses in the metallic sheets 80 and 81 as seen in FIG. 4, causes the volatile fluid to then pass with a regular flow from the first mixing zone to the first passage zone 85 (while the volatile fluid will absorb the heat transmitted by the metal sheets 80 and 81), while there will occur an additional mixture, although less energetic, of the volatile fluid. The volatile fluid will then pass through the second passage zone 86 formed in a similar manner to the first parallel passage zone 84 and so on as shown in FIG. 1 throughout the heat exchanger.

 If desired, multiple external heat exchangers 10 may further be connected together in series so as to obtain a greater distance over which the volatile fluid can circulate for the absorption of heat.

Claims (5)

CLAIMS 1. A closed circuit heater which is capable of extracting solar or non-solar heat energy from the surrounding atmosphere and using it to heat air, water or other fluids, the apparatus being characterized in that it comprises - a first heat exchanger (10), placed outside so as to be capable of absorbing non-solar heat from the surrounding atmosphere and solar heat directly from rays of the sun in sunny weather, said first heat exchanger including flow channels through which a volatile fluid passes; - a compressor (20); - a first set of conduits (11, 14, 17) connecting said first heat exchanger and said compressor; - a second heat exchanger (30), capable of heating air, water or other fluid; - a second set of conduits (22) connecting said compressor and said second heat exchanger; - an expansion valve (403; - a third set of conduits (31, 34, 37) connecting said second heat exchanger and said expansion valve; and - a fourth set of conduits (42) connecting said expansion valve and said first heat exchanger; and in that parts (11a) of said first set of conduits and (42a) of said fourth set of conduits closest to said first heat exchanger are placed sufficiently close together to obtain heat transfer between them.  2. Apparatus according to claim 1, characterized in that said parts of said first set of conduits and said fourth set of conduits are parallel to each other  3o Apparatus according to claim 22 characterized in that said parts of said first set of conduits and said fourth set of conduits are in direct mutual contact.  4. Apparatus according to claim 2 characterized in that said parts of said first set of ducts and of said fourth set of ducts are enclosed within a common enclosure,  5. Apparatus according to claim 1 characterized in that said parts of said first set of conduits and said fourth set of conduits are surrounded in the ground against each other.  6. Apparatus according to claim 1, characterized in that said second set of conduits includes inside an accumulation chamber (13) and a pressure regulator (16).  7. Apparatus according to claim 1, characterized in that said second set of conduits and said third set of conduits have in combination a shorter length than said fourth set of conduits.  Its method for extracting heat energy from the exterior of a building and for using it to heat air, water or another fluid, this method including the circulation of a volatile fluid through a first heat exchanger located outside in which said fluid is transformed from a liquid-vapor mixture into heated vapor, the passage of said vapor through a first set of conduits to a compressor in which it is still heated, the passage of said heated steam through a second set of conduits to a second heat exchanger in which it is used to heat air, water or another fluid and is at the same time changed into liquid, the passage of said liquid through a third set of conduits Up to an expansion valve in which it is transformed into a liquid-vapor mixture, and then the passage of said liquid-vapor mixture in a fourth set of fluid flow conduits up to the first heat exchanger, said method being characterized in that that it includes the positioning of said first heat exchanger so that it is capable of capturing the rays of the sun on sunny days and the positioning of parts of said first and fourth sets of conduits in the vicinity of said first heat exchanger with proximity narrow enough that heat transfer between the fluid passing through each set of conduits can take place  99 The method of claim 8, characterized in that said parts of said first and fourth sets of conduits are mutually parallel.  10. Method according to claim 8 characterized in that said parts of said first and fourth sets of conduits are placed so as to come into direct mutual contact,