GB1585528A - Heating and air conditioning system - Google Patents

Description

(54) HEATING AND AIR CONDITIONING SYSTEM (71) 1, ANDERS DANIEL BACKLUND, of Holmen, S-820 90 Ytterhogdal, Sweden, a citizen of Sweden, do hereby declare this invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be par ticularly described in and by the following statement:- The present invention relates to a heating and air conditioning system for objects or spaces surrounded by a heat insulating outer covering.

The invention particularly, but not exclu sively, relates to house buildings, which are heated by known heat distribution plants, for example by water heat and/or air heat conduits with appertaining heat bodies. Such heat distribution plants are at present dimensioned on the basis of the lowest ambient temperature during the year, for example expressed as a 24 hours average temperature. This dimensioning leads to high initial and operating costs, since the plant is over-dimensioned during the main part of the year.

The present invention seeks to make it possible to dimension heat distribution plants of the above mentioned kind for an ostensible ambient temperature being con siderably higher than the actual lowest 24 hourse average temperature. As an ex ample it may be mentioned that a heat dist ribution plant, which with the hitherto used technique must be dimensioned for a lowest 24 hours average temperature of about -20"C.(which is the case for large parts of Sweden), only needs to be dimensioned for a lowest temperature of e.g. --5"C when the system of the invention is used. Accord ing to the invention the hereby reduced heat demand is covered by using heat energy of a low temperature.

The invention also seeks to provide a simple, cheap and effective heat energy accumulator, which particularly makes it possible to store large amounts of low tem perature energy per unit of volume and the stored heat energy of which in a simple way may be transformed into useful heat energy in many different ways.

The invention also seeks to provide a heating and air conditioning system which not only makes it possible to reduce the need of high temperature energy during the cold season, but also allows cooling during the hot summer days.

The invention also seeks to efficiently be able to use solar energy and feed this energy to a heating system.

According to this invention we provide a heating and air conditioning system for objects and spaces surrounded by a heat insulating outer covering, said system comprising a ground accumulator for storing low temperature heat intended in use to contain a liquid capable of passing from liquid to frozen state and vice versa, a first heat exchanger system in heat exchanging contact with said ground accumulator, a second heat exchanger system which is positioned within said outer covering so as to be able to absorb transmission heat from both the outside and the inside of said covering, a conduit system interconnecting said first and second heat exchanger, and adjustable pumping means for circulating a heat carrying fluid between said first and second heat exchanger systems via said conduit system, so as to transfer heat from said ground accumulator to said outer covering and vice versa.The fundamental idea of this aspect of the invention is to utilise an accumulator, in which heat energy of a low temperature, e.g. about O"C, can be stored during the cold season, and to let this low temperature energy deliver heat to the second heat exchanger system in the outer covering during cold periods, for example with ambient temperatures lower than about O"C. Since the system in one aspect of the invention is to operate at temperatures below the freezing point of water, a heat carrying fluid with a lower boiling point than water is used, e.g freezing point depressed mixtures of water and one or more alcohols such as ethanol or glycol.

Such a low temperature energy accumulator may be formed in many different ways, but according to a preferred embodiment an accumulator device having heat storing masses in the form of a porous, highly water absorbing material, e.g. with a water absorb ing capacity of at least 70 /O and prefer- ably 80 - 90%, is used. Preferred water absorbing materials are peat, peat litter and similar materials.Since the accumulator is capable of raising the temperature of a heat carrying fluid having a lower temperature than about 0 C, the necessary heat for this temperature rise can be taken from water of 0 C being transfomed into ice without any lowering of the temperature; in other words the heat of freezing of the water is used, and because of the high water content in the accumulator it can store large amounts of low temperature energy (of about 0 C) per unit of volume, for example about 80 kWh/m3 storage volume when all the water freezes.The accumulator can be charged with heat from the sun, air, waste heat, water, the ground, etc., and the accumulator mass can be supplied with the heat directly, e.g. by conveying waste water etc. to the accumulator or the surrounding ground, or indirectly through tube systems, in which a heat carrying fluid is circulating, placed in the accumulator mass. Energy is drawn from the accumulator via suitable conduit systems having a circulating liquid or gas in them. The above described heat exchanging system in the outer covering of the object or the space to be heated draws heat from the accumulator at a low ambient temperature, but supplies the accumulator with heat during warm periods.

Apart from existing tube systems for the supply and withdrawal of heat energy the material of the accumulator is mainly peat and waste matter, and neither walls nor insulation is necessary if the accomulator is placed in suitable ground layers, natural pits, in earth fences and the like. The accumulator may advantageously be arranged in swampy areas, which up to now as a rule have not got any special use. Conduits leading to and from the accumulator get a simple location without causing heat losses, and the accumulator can be used for heat withdrawal or for cooling purposes during the whole year. It does normally not require any supervision or renewal, but any damages on tubes that may occur can easily be located and repaired.The accumulator device can be divided into the desired number of elements or separate sections and connected in series and in parallel for different purposes and temperature levels, and it is otherwise characterized by flexibility concerning adaption to ground conditions as well as to size and shape.

A so-called heat pump may be used for heating said object or space, whereat the heat pump by means of suitable tubing systems can be fed with low temperature energy from the accumulator device and/or the conduit system of the outer covering and transform this low temperature energy into high temperature energy for heating purposes. Such heat pumps have up to now practically exclusively been used as a complementary heat source, but owing to the reduced need of high temperature energy in the system according to the invention the heat pump may be responsible for all or the main part of this energy. The heat from the outlet side of the heat pump is utilized in a conventional way via heat exchangers, and the liquid or gas heated in this way is then made to heat the object or space in question by means of a suitable heat distribution system.

The system may be complemented with solar energy absorbing devices, which via suitable conduits with a heat carrying fluid can be connected to the heat exchanger system of the outer covering and/or the accumulator device and/or the heat pump system. The solar energy absorbing devices may not only be utilized to supply the heat pump with energy and to bring energy to the accumulator (t6 melt ice and to heat water and accumulator mass) and in this way reduce the necessary size of the accumulator, but they may also during many days and periods serve as the only energy source. If desired they may also be used for preheating water and for hot-water production, mainly during the summer halfyear.

Further features of the invention, to which the latter however is not restricted, are described in greater detail below with reference to the accompanying drawings, wherein Fig. 1 is a section view, which schematically shows the fundamental principle of the invention applied to a building; Figs. 2 and 3 correspond to Fig. 1 and show a system complemented with a heat pump and a solar energy absorber respectively; Fig. 4 is a cross-section view showing an embodiment of a heat exchanging insulating mat; Fig. 5 is a section view taken along A-A in Fig. 4; Fig. 6 is a schematic section view showing an embodiment of an accumulator device for the system according to the invention; Fig. 7 is a cross-section view of a solar energy absorber, which may be used in the system according to the invention; and Fig. 8 is a schematic section view illustrat mg different operating positions for the heating and climate equalizing system according to the invention.

The basic components of the heating and air conditioning system according to the invention appear from Fig. 1 showing a house building provided with a heat ex changing conduit system 1 in walls and roof and a heat energy accumulator 2. The conduit system 1 is suitably placed in the outer insulating layer of the house. The roof part la of the system may for example be arranged between the roof-trusses nearest to the roof-facing, while its wall portion ib is arranged between the wall joists nearest to the facade-facing. The heat exchanger system 1 is via tubing 3 and a circuation pump 4 in communication with the heat energy accumulator 2, the purpose of the circulation pump 4 being to transport heat carrying fluid between the heat exchanger system 1 and the accumulator 2.

It is obvious to a person skilled in the art that the detailed formation of the heat exchanger system 1 can be varied in many different ways, and the only critical feature of the system is that it shall be able to transmit heat between the fluid circulating in the conduit system la, 1b and the wall/ roof portions surrounding the system. The system should of course be arranged as regularly as possible and in a heat transmitting sense cover the whole roof and wall surfaces of the house. According to a preferred embodiment the conduit system 1 is formed as prefabricated blocks, which are interconnected at the assemblage. An example of a suitable arrangement of the conduit system 1 is shown in Figs. 4 and 5.In this embodiment a plurality of parallel tubes 5 with common collecting tubes 6 and connecting tubes 7 are arranged in a mat 8 of an insulating material, e.g. mineral wool.

The tubes 5 (6, 7) may be smooth or flanged, round or flat, and they may for example be made of a plastics material. The insulating mat 8 with the inserted tubes is suitably surrounded by a covering 9 of e.g. tar board, plastics film, etc., and the tubes 5, 6, 7 are preferably fixed in the mat 8, e.g.

by means of thread sewings 10. The tubes 5, 6, 7 need of course not be connected in parallel, but one may for example in each mat 8 use only one tube extending in zigzag-form through the whole mat. The connecting tubes 7, through which an energy carrying fluid, for example freezing point depressed water, is fed and removed, are coupled to a corresponding tube in an adjacent mat or are connected to suitable conduits with a connection to the accumulator 2.

The accumulator 2 shown schematically in Fig. 1 is buried in the ground adjacent to the house; it may e.g. be placed under the house. One of the main functions of the accumulator 2 is to supply the heat exchanger system 1 (and thereby also the house) with low temperature energy during cold periods, it being possible to use otherwise not usable energy for this purpose, e.g. from waste water, the surrounding ground, ventilating air, etc. According to a preferred embodiment the accumulator 2 is then provided with a storage mass having a high water content, through which it is possible to use the heat of fusion of the water practically and thereby reduce the volume of the accumulator. The accumulator 2 may in this case e.g. be formed as is shown in Fig. 6, where it is built-up by one or more relatively deep layers 11 of a water absorbing material, e.g. peat or peat litter.Through the water absorbing layer 11, the desired number of heat exchanger tubes or channels, in which a heat carrying fluid is circulating, extend. In Fig. 6 are for example air channels 12 and liquid conduits 13 shown schematically. The air channels 12 may e.g. be used for preheating ventilating air, outside air being taken in at 14, preheated in the channel 12 and passed on to the place of use (or preheated further) via a conduit 15. According to a preferred embodiment the heat exchanger tubes 13 are placed in outer tubes 16 filled with a buffer liquid having a lower freezing point than water. In this way the devices are prevented from getting burst with the frost, and repairs and building constructions in the winter time are possible.The freezing point depressed heat carrying liquid in the tubes 13 is supplied through feedconduits 17 and is after heat exchange taken out through conduits 18. Under certain conditions and to cover the tubes it is necessary to add crushed forest-waste as well as bark, which also may be used to protect the conduits 17, 18. Each element with tubes as well as surrounding layers of peat etc.

may be enclosed in a plastics film bag B, but this is not necessary in most cases.

The above described accumulator device functions in the following way. A liquid or a gas, which continuously is deprived of heat and thereby acquires a lower tempera- ture than the temperature in the accumulator device, is pumped through the inner tubes 13 and the air channels 12 respectively.

The fluid is then heated continuously a few degrees and heat energy may be taken out from the accumulator device as long as there is unfrozen water in it. If the fluids through the tubes 13 and channels 12 have a higher temperature than the accumulator device energy is supplied thereto, the ice volume being reduced (or the temperature being increased). The same thing happens when waste water, ground water, bottom water from a lake, a bog or the like is pumped or infiltrated to the accumulator, e.g. via inlet and outlet tubes 19 inserted in a filter 20 between the elements of the accumulator device. The tubes 19 are e.g. perforated tubes of a plastics or corresponding material, and the filter may consist of sand, bark, forest-waste, peat litter or a mixture of these materials depending on the ground etc.Especially if the accumulator device is fully or- partly used for preheating and cooling respectively of inlet and outlet air the element sections may be enclosed in plastics film bags B and arranged dryly with interspaces, which are left open or are filled with a suitable coarse gravel or stone material.

It is easily understood that the detailformation of the heat exchanger devices of the accumulator as well as the use of the transmitted heat energy may be varied in many different ways. Owing to the arrangement of the accumulator for utilization of the heat of fusion of the ice one can preserve an ice store in the accumulator until the end of the summer, and in this way a draughtless lowering of the room temperature during warm summer days can be attained with only a pump. Moreover, one can in an easy way attain temperature stable cold spaces without other additional mechanical equipment than tube coils and small liquid pumps, which can be thermo statically controlled. Furthermore, e.g. the channel system 12 may be formed in such a way that a fan blows outside air through the accumulator during mild weather days to charge it through ice melting.

Referring again to Fig. 1, the plant shown therein with a heat exchanger system 1 and an accumulator 2 is especially intended as a complement to primary heat sources (not shown in Fig. 1), free of cost waste and ambient heat of low temperature being utilized. The primary heating may be done by means of some conventional heat source (e.g. coke and oil heating, electric heating, municipal heating, etc.), the combination of heat exchanger system 1 and accumulator 2 considerably reducing the energy demand from the primary heat source, whereby also the dimensioning of the heat distribution system for the primary heat source may be reduced considerably. For a house in Cen tral Sweden it is possible to reduce the total energy demand by about 40"1, with the plant according to Fig. 1.

According to a further preferred embodiment of the invention, which is illustrated in Fig. 2, the plant shown in Fig. 1 is combined with a so-called heat pump 21, which in a conventional way converts low temperature energy to energy of a higher temperature, which may be used for e.g. house heating. The heat pump 21, which may be supplied with low temperature energy from the system 1, 2, 3 via conduits 22, supplies a heat distribution system 24 (e.g. for air or water heating) with heat via a heat exchanger 23. The heat pump 21 may also advantageously be used for heating household hot-water, to keep spaces for food storage temperature stable in the summer time, for drying air, etc.With the plant shown in Fig. 2 the energy demand for a Central-Swedish dwelling house may be reduced by about 70%, but the demand of additional energy may be reduced further (totally about 80%) by combining the plant according to Fig. 2 (alternatively Fig. 1) with a solar energy absorber 25, which in the shown case is placed on the house wall, but which also may be arranged on the house roof or separately. The solar energy absorber 25 is via suitable conduits (in Fig. 3 marked with 48 and 49) connected to the accumulator 2 and the heat pump 21. It suitably also communicates with the tube system 1 and may for example form a part of this tube system.The solar energy absorber 25, which absorbs solar energy and via a heat carrying fluid gives it off to the accumulator 2 and/or the heat pump 21 and/or the tube system 1, may be formed in a conventional way - e.g. with heat exchanger tubes arranged to collect energy from the reflectors -- or be specially made for the purpose in question.

In Fig. 7 a preferred embodiment of the solar energy absorber 25 is shown, which in this case includes a profile 26 with an inner cavity 27. The profile 26, which suit ably is made of a heat insulating material, e.g. a transparent plastic with air cells, is suitably injection-moulded. The cavity 27 is filled with a liquid standing low tem peratures without causing frost-cracking of the profile, e.g. freezing point depressed water. The liquid may possibly be absorbed in a liquid absorbing mass. Through the cavity 27 also one or more heat exchanger tubes 28, in which the heat carrying fluid circulates, extend. The tubes 28 may be injection-moulded simultaneously with the profile 26 or be separated from it and mae of another material.The described profile or panel is preferably formed as a roof or wall facing, and it is well suited for col lecting solar energy which via the water mass in the spacing 27 is transmitted to the heat carrier in the tubes 28. Further more heat loss in the form of transmission energy from a covered wall (or roof) may be recovered, and the panel may advan tageously be built-in in the above de scribed tube system 1.

In the combination shown in Fig. 2 of a tube system 1, an accumulator 2 and a heat pump 21 the heat pump may, as mem tioned above, be utilized for heating in many different ways.

Fig. 8 shows a complete heating and air conditioning system with a heat exchanger system 1, an accumulator 2, a heat pump 21 and a solar energy absorber 25. In this case the heat pump 21 includes inter alia a compressor 40, a condenser 41, an ex 'passion valve 42, and an evaporator 43, which is arranged for heat exchange in a liquid tank 44. The tank 44 may advantageously be formed as directly energy absorbing, e.g. of solar energy, or as elements arranged to be placed in animal stables, etc. for drying of air and recovery of excess heat.

Fig. 8 shows some examples of how, depending on the season and the heat demand, one can choose different operating positions and in an optimal way use different combinations of the systems 1, 2, 21 and 25. The fine regulation is then done in a known way with start and stop etc. via thermostats. The designations Ll, L2 etc. in Fig. 10 indicate the parts of the conduit system that are connected in the different operating positions, the designations 45 and 46 indicate suitable switchvalves, and Pl and P2 indicate pumps for circulation of a heat carrying fluid in the system Operating position la. The pump P, is started and pumps liquid through the conduits designated by L1. The result in this operating position will be a temperature equalization between the different parts of the outer covering, e.g. from roof to northern wall.

Operating position ib. Corresponds to operating position la, but heat energy from the solar energy absorber 25 is added.

Operating position 2. Corresponds to operating position lb, but the heat carrying fluid passes the tank 44 and the compressor 40 is started. Heat is taken from 1 and 25.

In addition operating heat from the compressor 40 is added. The heat is brought to the spaces 47 via a heat distribution plant 48 of a known kind.

Operating position 3a. Corresponds to operating position 2, but the temperature in 1 and 25 becomes "uneconomically" low and may under certain conditions cause deposition of moisture at a full heat-outtake, for which reason also the accumulator 2 is connected. The temperature in 1 and 25 is then limited to not less than --5"C.

Operating position 3b. In case of severe cold the heat absorbing capacity js increased by connecting the second pump P, which also is a reserve pump. In practice the heat absorbing surfaces of the accumulator are increased at first hand. The heat from the accumulator is then not only sufficient for supplying the heat pump system with energy but in addition 1 is supplied with the necessary heat energy between the temperatures about 50C and --1"C, taken when water is freezing in 2, so that the heat losses from 1 against the outside air and the severe cold can be compensated.

Operating position 4. The pump P, circulates the liquid through 2 and 44, when 44 tends to get too warm. In this way an unnecessary high pressure in the heat pump 21 is prevented. This is a kind of position of rest in the summer time, when a smaller amount of liquid, when necessary, is cooled for certain purposes, such as for cooled spaces, cellars, etc.

Operating position 5a. At a high load within the spaces 47 heat is taken from 1, which through circulation is brought to the accumulator 2. A draught-free lowering of the temperature or a maintained desired temperature is then obtained in 47.

Operating position 5b. The accumulator is supplied with heat from 25.

Operating position 6. At an extra high heat load, e.g. in hot weather, lots of people.

heating processes, machines, etc., the compressor 40 is started. Heat is taken from 1.

The condenser cooling in the heat pump system 21 is switched over to 2 (not shown) or to coils for earth heating, heating of pool water etc. instead of heating the spaces 47.

The invention is of course not restricted to the embodiments described above and shown in the drawings, but many modifications and variations are possible within the scope of the general idea of the invention, as it is stated in the subsequent

Claims (17)

claims. WHAT I CLAIM IS:

1. A heating and air conditioning system for objects and spaces surrounded by a heat insulating outer covering, said system comprising a ground accumulator for storing low temperature heat intended in use to contain a liquid capable of passing from liquid to frozen state and vice versa, a first heat exchanger system in heat exchanging contact with said ground accumulator, a second heat exchanger system which is positioned within said outer covering so as to be able to absorb transmission heat from both the outside and the inside of said covering, a conduit system interconnecting said first and second heat exchanger, and adjustable pumping means for circulating a heat carrying fluid between said first and second heat exchanger systems via said conduit system, so as to transfer heat from said ground accumulator to said outer covering and vice versa.

2. A system according to claim 1, wherein said heat exchanger system is arranged on the outside of the centre in a heat insulating sense, of the outer covering.

3. A system according to claim 1 or 2, wherein said heat exchanger system substantially extends over the whole of said outer covering.

4. A system according to claim 1, 2 or 3, wherein said heat exchanger system comprise a tube system in which said fluid circulates.

5. A system according to any one of the preceding claims, wherein said fluid con sists of an aqueous mixture with a lower freezing point than water.

6. A system according to any one of the preceding claims, wherein said ground accumulator comprises a water absorbing mass, through which a plurality of heat exchange conduits extend.

7. A system according to claim 6, wherein said water absorbing mass is peat, peat litter or a similar material.

8. A system according to any one of the preceding claims, wherein a solar energy absorbing device is connected to said conduit system.

9. A system according to claim 8, wherein said solar energy absorbing device is formed as a preferably injection-moulded panel, provided with a closed cavity containing, on one hand, a liquid or a wet mass, which stands low temperatures without causing frost-cracking of the panel, and, on the other hand, tubes, through which said fluid circulates, connected to said conduit system.

10. A system according to any one of the preceding claims, wherein a heat pump, which is arranged to heat said object or space, is connected to said conduit system.

11. A system according to claim 10, wherein said heat pump has an evaporator section which is arranged to absorb low temperature heat from said conduit system and a condensor section which is arranged to supply heat to a system for direct heating of said object or space.

12. A system according to claim 10 or 11, wherein circulation pumps and controlled valve means are arranged to permit transport of heat energy via said conduit system, so that solar energy and excess energy from said object or spaces and their environment can be accumulated and accumulated energy and/or solar energy be transmitted to said second heat exchanger system, which makes it possible to attairt, on one hand, a more uniform local di- tribution of heat energy, and, on the other hand, a heat transfer from warmer to colder time periods and thereby an addition during colder periods of heat energy via said outer covering to said object or spaces, which in its turn permits reduced dimensions of said heat distribution plant and said heat r)u!np.

13. A system according to claim 12, wherein said pumps are connected in parallel and on one side to one end of a conduit through said ground accumulator and a conduit to a first valve means, and on a second side to a liquid tank being an integral part of the heat pump and a second valve means, and wherein one etid of a conduit through said second heat e,.- changer system and one end of a conduit through said solar energy absorbing device are connected to said first valve means, and the other end of said conduit through said second heat exchanger system as well as a conduit via said tank to said first valve means, to which also the other end of said conduit through said ground accumulator is connected are connected to said second valve means.

14. A heating and air conditioning system according to claim 1 substantially as described herein.

15. A heating and air conditioning system substantially as shown in the accompanying drawings and described herein with reference thereto.

16. A method of heating and air conditioning objects and spaces surrounded by a heat insulating outer covering, comprising the steps of withdrawing heat from a ground accumulator containing a liquid capable of passing from liquid to frozen state and vice versa when the outside temperature is below freezing and supplying the heat to the surrounded space so as to raise the temperature thereof to freezing temperature and, when the outside temperature is above freezing, intercepting heat which is transmitted through the outer covering into or out of the surrounded space - and supplying the intercepted heat to a heat exchanger.

17. A method according to claim 16 substantially as described herein.