WO2013153284A1

WO2013153284A1 - Method and arrangement for utilizing energy

Info

Publication number: WO2013153284A1
Application number: PCT/FI2013/050398
Authority: WO
Inventors: Jussi Reijonen
Original assignee: Veli Reijonen Oy
Priority date: 2012-04-13
Filing date: 2013-04-11
Publication date: 2013-10-17
Also published as: FI20125406A

Abstract

The invention relates to a method and arrangement for utilizing energy, the method comprising transferring energy contained in the ground (1) to the surface of earth to be used for heating or cooling. At least one air well (2) is formed into air permeable ground (1) and air is conveyed from the air permeable ground (1) into the air well (2) and further up from the air well (2) to be conveyed to heat recovery apparatuses (3).

Description

METHOD AND ARRANGEMENT FOR UTILIZING ENERGY

[0001] The invention relates to a method for utilizing energy, in which method energy contained in the ground is transferred to the surface of earth to be used for heating or cooling. The invention also relates to an arrangement for utilizing energy.

[0002] Today, use of geothermal heat is extremely widely known. The term 'geothermal heat' is used for solar heat energy stored in the ground or in a water body. Thermal energy produced by ground source energy may be used for heating buildings and domestic water.

[0003] An essential element in a system using geothermal heat is a piping placed in the topsoil, bedrock or water. Inside the piping there is liquid that is circulated and heats up by the influence of heat contained in the ground, rock or water surrounding the pipe. Different suitable liquids may be used, such as bioethanol, which has a low freezing point. When circulating in the piping, the liquid extracts thermal energy for the surrounding material and transfers it to a desired location, i.e. to a heat recovery apparatus, for use.

[0004] The above-mentioned piping is most commonly mounted to drill hole drilled vertically to the rock, i.e. to form what is known as a thermal well. A piping laid into water requires a shore where the water depth increases rapidly to some meters. The piping is fastened to the bottom at a depth of at least three meters. A piping to be laid into ground is most often placed into a horizontal position. This mounting method is suited for large sites and surfaces. The laying of the piping does not impede gardening or harm plantations.

[0005] A restriction with regard to piping to be mounted to rock or laid into water is that the mounting methods in question cannot be used everywhere, i.e. in some places the bedrock may be fairly deep down, and a suitable water area is not available everywhere either. A further point to be noted with regard to water areas is that a piping is preferably not installed into a running river, for example, and, in addition, mounting into water always requires an authorization from the owner of the water area, which may in some cases be problematic to get.

[0006] A piping to be laid horizontally into the ground has its advantages. The piping may be placed into almost any type of ground. An exception, however, is porous ground, such as an esker, where a piping cannot be placed. This restricts the use of ground heat for heating buildings built in esker areas, for example. In practice this is a significant drawback and up to now there has been no way to overcome it.

[0007] The object of the invention is to provide a method that allows the prior art disadvantages to be eliminated. This is achieved by a method according to the invention. The method of the invention is characterized by forming at least one air well/cavity into air permeable ground and conveying air from the air permeable ground into the air well/cavity and, further, up from the air well/cavity to be conveyed to heat recovery apparatuses. An arrangement of the invention, in turn, is characterized in that the arrangement comprises at least one air well/cavity formed into air permeable ground for conveying air from the air permeable ground into the air well/cavity and further up from the air well/cavity, and that the arrangement further comprises heat recovery apparatuses arranged into the air stream conveyed from the air permeable ground.

[0008] An advantage of the invention, above all, is that it is now possible to use ground heat also in association with buildings in esker areas. A further advantage of the invention is its simplicity and versatility. Due to the simple solution, the introduction into use and use of the invention are affordable. Because of its versatility, the invention may be applied in an affordable manner to heat buildings of extremely varying sizes. It is also possible to apply the invention so that cool air obtained from the ground may be utilized as cooling air in summer, for example, by using the air for different cooling needs of apartments or industry. This type of application is extremely useful during a warm summer season, for example, or even all year round in warm climates.

[0009] The invention will be explained in the following in more detail by means of application examples described in the attached drawing, in which

Figure 1 is a general view of an embodiment applying the method of the invention,

Figure 2 is a general view of a second embodiment applying the method of the invention,

Figure 3 is a general view of a third embodiment applying the method of the invention,

Figure 4 is a general view of a fourth embodiment applying the method of the invention,

Figure 5 is a general view of a supplementary implementation of the embodiment of Figure 4, Figure 6 is a general view of a fifth embodiment applying the method of the invention,

Figure 7 is a general view of a sixth embodiment applying the method of the invention, and

Figure 8 is a general view of a seventh embodiment applying the method of the invention.

[0010] Figure 1 is a general view of an embodiment utilizing the method of the invention. Reference numeral 1 denotes ground impermeable to air. In this context the term "porous ground" refers to porous ground that may be a layer of sand or gravel, for example, which may also contain rocks and blocks.

[0011] Reference numeral 2 denotes an air well/cavity in Figure 1 . Reference numeral 3 in Figure 1 denotes generally an apparatus for heat recovery, i.e. an apparatus for recovering heat for use. The heat may be used for heating an inside of a building, for example.

[0012] In this context the term heat well/cavity 2 should be interpreted broadly, i.e. to cover not only a well-type cavity made into porous ground but also other structures forming a cavity and/or a recess and made into porous ground etc.

[0013] With reference to Figure 1 , at least one air well/cavity 2 is formed in accordance with the invention into the air permeable ground 1 permeable. In accordance with the invention, air is conveyed from the ground 1 to the air well/cavity 2 and further up from the air well/cavity 2 to be conveyed to the heat recovery apparatuses 3. In Figure 1 the flow of air contained in the air permeable ground 1 into the air well/cavity 2 is depicted with arrows. The air that has flown into the air well/cavity 2 continues to flow up the air well/cavity and out of the air well/cavity to be conveyed to the heat recovery apparatuses 3.

[0014] In other words, the essential idea of the invention is to obtain air from porous ground 1 permeable to air and not saturated by water through at least one air well/cavity 2 and to utilize the thermal energy contained in the air either for heating or cooling, depending on the surrounding temperature. In this context, the term ground not saturated by water refers to a layer of air permeable ground and situated between earth surface and groundwater or perched water. [0015] As disclosed above, at least one or more air wells/cavities 2 are formed to the porous ground 1 . The depth of the air well may vary depending on the situation. The air well is formed by means of suitable drilling means, for example. When the air well is being made, openings, i.e. gaps and open pores, are formed to the walls and/or bottom of the air well, to allow air contained in the ground to flow into the air well 2 and further along the air well to the heat recovery apparatuses 3.

[0016] If necessary, the walls of the air well/cavity may be reinforced by means of a suitable porous material, such as a suitably rigid plastic material with gaps or holes to provide a mesh-like or sieve-type structure, for example. The size of the gaps or holes is dimensioned according to the composition of the ground, if necessary.

[0017] In accordance with the inventive idea, the invention may also be applied by arranging an air blower 4 in association with the air well/cavity 2. The air blower 4 may be arranged to suck air from the air well/cavity, in which case air contained in the ground, i.e. in the pores of the ground, is allowed particularly advantageously to flow from the ground into the air well/cavity. Figure 2 is a schematic view of this type of implementation. Like parts are denoted with like reference numerals in Figures 1 and 2.

[0018] The suction produced by the air blower 4 makes the air contained in the porous ground flow into the air well/cavity 2 and further to the apparatus 3 used for heat recovery.

[0019] The air blower 4 may be arranged in the vicinity of the opening of the air well/cavity 2, for example, as schematically shown in Figure 2.

[0020] According to Figures 1 and 2, there is one air well/cavity 2 formed into the air permeable ground 1 . This is not, however, the only option, but the essential idea of the invention may also be applied to form a plural number of air wells/cavities 2 to the air permeable ground. Figure 3 is schematic view of an embodiment in which the air permeable ground 1 is provided with nine air wells/cavities 2. In this type of implementation the air wells/cavities 2 may be of equal or different depths. Like parts are denoted with like reference numerals in Figures 1 , 2 and 3.

[0021] An implementation with a plural number of air wells 2 may be provided in accordance with the principles of Figures 1 or 2, i.e. without an air blower like the one in Figure 1 , or by connecting one or more air blowers to the air wells/cavities in accordance with the basic principle disclosed in Figure 2. Figure 3 shows an implementation without an air blower.

[0022] The operation of the implementation of Figure 3 is similar to what is disclosed in association with Figures 1 or 2.

[0023] If an air blower is used in the implementation of Figure 3, the basic principle may be applied in a number of ways. For example, the basic principle mentioned above may be applied by providing each air well/cavity 2 with a separate air blower 4. Alternatively, the invention may be applied so that one and/or some of the air wells/cavities 2 have a separate air blower 4 while other air wells/cavities 2 have, correspondingly, a common air blower 4. Moreover, it is possible that all the air wells/cavities 2 have a common air blower 4.

[0024] An additional characteristic of an implementation employing one or more air blowers is that the air blower 4 may also be used for transferring energy into the porous air permeable ground and to store it into the air permeable ground for later use. This kind of functionality may be used during warm seasons, for example in summer, when the air blower 4 is arranged to blow warm air into the air well/cavity from where the warm air is allowed to flow into the air permeable ground. This warms up the air permeable ground surrounding the air well. Later, on colder seasons, for example in winter or autumn, the above-mentioned stored thermal energy may be utilized by conveying or sucking air from the porous ground, as disclosed above with reference to Figures 1 to 3.

[0025] The heat recovery apparatuses 3 may be any apparatuses known per se. For example, the heat recovery apparatuses may comprise one or more heat exchangers.

[0026] In a particularly preferred implementation of the invention the heat exchangers 3 comprise a heat pump. An advantage of this type of implementation is that the invention allows the heat pump to be made to work well also in sub-zero temperatures. A known problem with heat pumps is that in sub-zero temperatures the efficiency of the air pump drops and, in the worst case, the air pump may even cease to operate. The invention allows warm air to be obtained from the ground for the air pump even if the outside temperature was too low for the operation of the air pump.

[0027] Figures 4 to 8 are schematic views of different embodiments applying the method of the invention. The same reference numbers are used in Figures 4 to 8 as in Figures 1 to 3 to refer to the corresponding parts. [0028] In the embodiment of Figure 4 some of the heat recovery apparatuses 3, i.e. the heat exchanger 3a, are arranged into the air well/cavity 2. The air conveyed from the ground flows through the heat exchanger 3a. The medium flowing in the heat exchanger 3a, such as liquid or gas, is conveyed to a separate device 3b placed into a heated space, for example. The medium heats up as usually in the heat exchanger. The above-mentioned separate device 3b transfers the heat energy contained in the liquid into the heated space. Today, the above-mentioned separate devices are more often heat pumps, although also heat exchangers may be used for the purpose in question.

[0029] In relation to the matters disclosed above, it is to be noted that when heat is taken from outside air, the humidity contained therein tends to freeze from time to time into the heat exchanger. Freezing occurs particularly when the outside air is cool or cold. Ice formed to the surface of the heat exchanger reduces the transfer of heat energy into the liquid or gas flowing inside the heat exchanger. For this reason ice is defrosted usually by transferring heat energy from the heated space to the heat exchanger. This operation reduces the efficiency of the device.

[0030] Outside temperature varies greatly during different times of the day and the year. When heat is taken from the air or conveyed into the air, the apparatuses are required to operate within a large temperature range. For this reason the apparatuses are complex and their efficiencies change radically as the temperature of air changes. When the outside temperature is at its lowest, the highest thermal capacity is needed. Likewise, when the temperature of the outside air is at its highest, the highest cooling capacity is needed. Current air source heat pumps do not operate at their highest efficiency in either case. Placing the heat exchanger into the flow of air conveyed from the ground allows the heat energy contained in the ground to be taken efficiently into use. At times, humidity contained in the air flowing from the ground may freeze onto the heat exchanger. Placing the heat exchanger to a warm environment allows the amount of defrosting to be essentially reduced, which increases the efficiency of the apparatus. Defrosting is carried out making use of the warm air flowing from the ground. Placing the heat exchanger into the flow of air conveyed from the ground, where temperature variations during the day and the year are small, allows the dimensioning of the device connected to the heat exchanger to be optimized to a narrow temperature range and thus its efficiency to be improved. In Finland outside temperature varies between about -30 and +30°C, whereas the temperature of air from the ground varies between about +2 and +12°C. At the same time the structure of the device connected to the heat exchanger is simplified. Placing only the heat exchanger 3a into a flow of air containing a lot of humidity, as shown in Figure 4, increases the service life of other devices in the system.

[0031] Figure 5 shows a supplementary implementation of the embodiment of Figure 4. In Figure 5, the same reference numerals as in Figure 4 are used at corresponding points.

[0032] The embodiment of Figure 5 differs from the one in Figure 4 in that in the embodiment of Figure 5 one and the same circuit contains at least two heat exchangers 3a1 and 3a2. The heat exchangers 3a1 and 3a2 may be placed one after the other or even into two underground structures for conveying air, such as the air well/cavity 2. Figure 8 is a schematic view of this embodiment. The same reference numerals are used in Figure 8 as in Figure 5 to refer to the corresponding parts.

[0033] The principle in Figure 5 as well as in Figure 8 is that when the cells of one heat exchanger are frozen, they may be defrosted by closing the respective circuit by valves 5 or 6. While the cells of the heat exchanger are defrosted in a warm flow of air, the cells of the other heat exchanger are in use. The cells of the heat exchangers may be defrosted in any order whatsoever by means of the valves. Likewise, the power and efficiency of the system may be effectively optimized by adjusting the valves and the air flows. When the above procedure is followed, heat production operates without interruptions. The heat exchangers may be designed without a need to take into account condensation and melt water control because they flow into the porous ground.

[0034] Figure 6 shows an embodiment in which air from the ground is conveyed for heating/cooling purposes by an air well/cavity 2 with a bottom surface 8 permeable to air. In the embodiment of Figure 6 there are two air wells/cavities 2, one outside the heated space and the other, correspondingly, as a part of the structures of the heated space. The same reference numerals are used in Figure 6 as in the previous figures to refer to the corresponding parts. In this context the term 'bottom surface' should be understood broadly, for example so that the bottom surface may continue from the bottom also to the wall at least on a portion of the length of the circumference. In addition, the walls of the air well/cavity 2 may have porous areas. [0035] Figure 7 shows an embodiment in which the air well/cavity 2 is in fact formed of the underground structures of a building to be heated, with at least one porous area 7 being provided in the structures for conveying air from the porous ground to heating/cooling purposes. The same reference numbers are used in Figure 7 as in the other figures to refer to the corresponding parts.

[0036] Figure 7 also shows an implementation in which the air well/cavity 2 is formed as a substantially horizontal structure for taking air from the porous ground for heating/cooling purposes. In this type of implementation the air well/cavity 2 may also be a porous structure. The embodiment described above and also the embodiments disclosed in the other figures may also be implemented by means of an air well/cavity in a vertical or inclined orientation.

[0037] To mention a practical example of the application of the invention, a trial arrangement was made in winter 201 1 to 2012 with an industrial hall to be heated, the volume of the hall being 1500 m³ and its inside temperature 12 to 20 degrees. Air was taken from air permeable ground in accordance with the invention from one air well of a diameter of 400mm. Heat recovery was carried out by an air source heat pump through which the air sucked from the air permeable ground via the air well was conveyed. The air source heat pump worked normally even though outside temperature was below 20 degrees. After being used for over 4 months, the temperature of the air sucked from the air permeable ground was about 8 degrees.

[0038] The above example illustrates well the advantages gained by the invention in comparison with the prior art. The invention allows heat energy contained in air permeable ground to be utilized and thus a small amount of external energy allows a large amount of energy to be recovered also during the coldest seasons. It is to be noted that invention provides an affordable means of efficiently using air source heat pump technology also during the cold seasons. In this connection a particular note to be made is that the invention allows energy contained in the ground to be used in association with buildings in esker surroundings, for example, where prior art ground heat solutions are not suitable or they are expensive to implement.

[0039] The invention is described above by means of application examples shown in the figures. However, the invention is in no way restricted to the examples of the figures but may be freely applied within the scope of the accompanying claims.

Claims

1 . A method for utilizing energy, in which method energy contained in the ground (1 ) is transferred to the surface of earth to be used for heating or cooling, characterized by forming at least one air well/cavity (2) into air permeable ground (1 ) and conveying air from the air permeable ground (1 ) into the air well/cavity (2) and, further, up from the air well/cavity (2) to be conveyed to heat recovery apparatuses (3).

2. A method as claimed in claim 1 , characterized in that more than one air well/cavity (2) is formed.

3. A method as claimed in claim 1 or 2, characterized in that an air blower (4) is arranged in association with the air well/cavity (2), the air blower being configured to suck air from the air well/cavity (2).

4. A method as claimed in claim 3, characterized in that the air blower (4) is arranged in the area of the opening of the air well/cavity (2).

5. A method as claimed in any one the preceding claims 2 to 4, characterized in that each air well/cavity (2) is provided with a separate air blower (4).

6. A method as claimed in any one the preceding claims 2 to 4, characterized in that more than one air well/cavity (2) is provided with a common air blower (4).

7. A method as claimed in any one the preceding claims 2 to 4, characterized in that all the air wells/cavities (2) are provided with a common air blower (4).

8. A method as claimed in any one the preceding claims 2 to 7, characterized in that the air blower (4) is arranged to blow warm air into the air well/cavity (2) from where the warm air is allowed to flow into the air permeable ground (1 ).

9. A method as claimed in any one of the preceding claims 1 to 8, characterized in that the heat recovery apparatuses (3) comprise a heat exchanger (3a, 3a1 , 3a2).

10. A method as claimed in any one of the preceding claims 1 to 8, characterized in that the heat recovery apparatuses (3) comprise a heat pump.

1 1 . A method as claimed in any one of the preceding claims 1 to 10, characterized in that the air well/cavity (2) is formed as at least a part of an underground portion of a building.

12. An arrangement for utilizing energy, the arrangement being arranged to transfer energy contained in the ground to the surface of earth to be used for heating or cooling, characterized in that the arrangement comprises at least one air well/cavity (2) formed into air permeable ground (1 ) for conveying air from the air permeable ground into the air well/cavity and further up from the air well/cavity (2) and that the arrangement further comprises heat recovery apparatuses (3) arranged into the flow of air conveyed from the air permeable ground (1 ).

13. An arrangement as claimed in claim 12, characterized in that the heat recovery apparatuses are at least partly arranged into the air well/cavity (2).

14. An arrangement as claimed in claim 12 or 13, characterized in that the air well/cavity (2) is formed as at least a part of an underground portion of a building.

15. An arrangement as claimed in any one of the preceding claims 12 to 14, characterized in that the arrangement comprises an air blower (4).

16. An arrangement as claimed in any one of the preceding claims 12 to 15, characterized in that the heat recovery apparatuses (3) comprise at least one heat exchanger (3a, 3a1 , 3a2).

17. An arrangement as claimed in any one of the preceding claims 12 to 16, characterized in that the heat recovery apparatuses (3) comprise a heat pump.

18. An arrangement as claimed in any one of the preceding claims 12 to 17, characterized in that the heat well/cavity (2) is formed as a structure with a bottom surface (8) permeable to air.

19. An arrangement as claimed in any one of the preceding claims 12 to 18, characterized in that the air well/cavity (2) is formed of an underground structure of a building, an area (7) permeable to air being formed to a part of the structure.

20. An arrangement as claimed in any one of the preceding claims 12 to 19, characterized in that the air well/cavity (2) is formed as a substantially horizontal porous structure.