The invention relates to a container according to the preamble of claim 1 for heating wastewater or recovering its thermal energy.

In apartment buildings, especially, there is generated a considerable amount of so-called grey and black wastewater. Although such wastewaters have a relatively low temperature (about 20-30°C), over the range of 10-100°C, the amount of thermal energy retained in wastewater (about 10-30% of the waste energy of an apartment building) is nevertheless substantial due to the large amount of wastewater.

At the moment, there is not available in the marketplace an efficient recovery system for the waste heat of wastewaters as a result, among other things, of the low temperature of wastewaters, thereby limiting utilization of this particular energy flow in higher energy temperature demanding services, such as e.g. in connection with district heating.

It is an objective of the invention to eliminate the aforementioned prior art drawback and to provide an efficient recovery apparatus for thermal energy retained explicitly in the black and gray wastewaters of apartment buildings.

The invention relates to a container according to claim 1 intended for heating wastewater or recovering its thermal energy.

More specifically, the invention relates to a container for heating wastewater or recovering its thermal energy. The container comprises a first inlet for a wastewater supply pipe and a first outlet for a wastewater discharge pipe. A wastewater pipe extending within an interior of the container, between the inlet and the outlet of the wastewater supply pipe, is continuous and constructed in a spiral shape, and the container further includes at least one second inlet for a supply pipe of a heat transfer fluid arriving in the container, as well as at least one second outlet for a discharge pipe of a heat transfer fluid departing from the container, the heat transfer fluid provided in the container's interior being adapted either to recover thermal energy of the wastewater traveling in the wastewater pipe installed within the container's vacant interior or to release thermal energy to the wastewater traveling in the wastewater pipe installed within the container ^' s vacant interior. It is a basis of the invention that wastewater arriving in the container is conducted through a wastewater pipe, which extends through the container and is in a spiral shape, thus providing an increase in a heat transfer area of the pipe. The energy of relatively low temperature wastewater passing through the spirally shaped wastewater pipe is either transferred to a heat transfer fluid present in the container around the pipe and having a temperature lower than that of the wastewater, such as to a heat recovery fluid in the primary loop heat of a heating system that comprises a heat pump, or the wastewater is used for taking up extra energy from a heat transfer fluid or refrigerant (subsequently also cooling fluid) traveling in the condenser loop of a building cooling system.

Wastewater in this application refers to dirty or clean water having a relatively low temperature: hence, wastewater may refer either to grey or black water categorized traditionally as wastewaters and originating from kitchen, sauna, shower or the like or also to condensation water obtained from a building heating or cooling system.

In a preferred embodiment of the invention, between the supply pipe inlet for a heat transfer fluid arriving in the container as well as the discharge pipe outlet for a heat transfer fluid departing from the container is established a fluid communication through the heat transfer fluid present in the container's vacant interior, said heat transfer fluid being preferably a refrigerant (cooling fluid) for the condenser loop of a building cooling system, which is condensed in the container's interior. Hence, the cooling fluid is adapted to travel primarily in a direction countercurrent to the average wastewater flow direction in the container's interior. This embodiment of the invention provides the benefit of enabling the temperature of a refrigerant traveling in the cooling system's condenser loop to be reduced with the heat of a wastewater flow traveling in the container's interior, and thereby to reduce the required refrigerant compressor performance and to increase the overall heat pump performance.

In another preferred embodiment of the invention, between the supply pipe inlet for a heat transfer fluid arriving in the container as well as the discharge pipe outlet for a heat transfer fluid departing from the container is established a fluid communication through the heat transfer fluid present in the container's vacant interior, and the heat transfer fluid is a heat recovery fluid which travels in the primary loop of a heat pump-equipped heating system or which is in a fluid communication therewith. Hence, the heat recovery fluid is adapted to travel primarily in a direction countercurrent to the average wastewater flow direction in the container's interior. This embodiment of the invention provides the benefit of enabling the temperature of the heat pump's recovery fluid to be increased with the heat of a wastewater flow traveling in the container's interior. This in turn increases the vaporization pressure of the heat pump's refrigerant, thereby raising the overall heat pump performance (COP).

In another preferred embodiment of the invention, between the supply pipe inlet for a heat transfer fluid arriving in the container as well as the discharge pipe outlet for a heat transfer fluid departing from the container is provided a continuous spiral-shaped heat transfer pipe tracing along an outer surface of the spiral-shaped wastewater pipe at least over a part of the heat transfer pipe's length. In the spiral-shaped heat transfer pipe flows either service water to be heated or some other heat transfer fluid to be heated and it travels primarily in a direction countercurrent to the average wastewater flow direction in the container's interior. The embodiment of the invention provides the benefit of enabling the temperature of service water or other heat transfer fluid to be effectively increased with the heat of a wastewater flow traveling in the container's interior.

In another preferred embodiment of the invention, the container is provided with a spiral-shaped heat transfer pipe and, in addition, the cooling fluid is adapted to travel primarily in a direction countercurrent to the average wastewater flow direction in the container's interior as described above. This embodiment of the invention provides the benefit of enabling the temperature of refrigerant traveling in the condenser loop of a cooling system to be first reduced with the heat of a wastewater flow traveling in the container's interior, and thereafter further enabling the heat energy of higher-temperature wastewater, flowing in the spiral- shaped wastewater pipe, to be used for increasing the temperature of service water flowing in the spiral-shaped heat transfer pipe, especially in a service water preheating coil.

In yet another preferred embodiment of the invention, the container is adapted to be pressurized by providing it with a double jacket. The benefit of such a container design is the possibility of pressurizing the heat transfer fluid conductible into the container's interior or inside the double jacket. The concepts of the heat transfer fluid traveling primarily in a direction countercurrent to or co-current with the average wastewater flow direction in the container's interior refer to the following: the flow direction of wastewater inside a spiral-shaped wastewater pipe changes constantly, yet its average flow direction in the container's interior is parallel to a median line of the spiral-shaped wastewater pipe. The flow direction of a heat transfer fluid inside the container may also fluctuate, e.g. because of other structures in the container's interior and a shape of the container. Its flow direction is nevertheless primarily or for the most part either co-current with or countercurrent to wastewater traveling inside the spiral-shaped wastewater pipe, the latter having in turn its traveling direction parallel to a median line L of the spiral-shaped wastewater pipe. in a preferred embodiment of the invention, one or more heat transfer pipes for heat transfer fluids arriving in the container are adapted to extend to the inside of a spiral made up by the spiral-shaped wastewater pipe. Preferably, the heat transfer pipes extending inside the spiral formed by the spiral-shaped wastewater pipe are spirally shaped at least over a part of the heat transfer pipe's length along a section extending in juxtaposition with the spiral-shaped wastewater pipe. In a preferred embodiment of the invention, the spiral-shaped heat transfer pipes for heat transfer fluids, which extend inside a spiral made up by the container's spiral-shaped wastewater pipe, are arranged in the form of spirals of various sizes within the spiral made up by the spiral-shaped wastewater pipe, whereby the spirals of heat transfer pipes can be fitted in a nested fashion relative to each other and the spiral-shaped wastewater pipe. Alternatively, the spiral-shaped heat transfer pipes for heat transfer fluids are of equal size. Preferably, the spiral- shaped heat transfer pipes are arranged in the container in a side-by-side or overlapping relationship. A benefit gained by spiral-shaped heat transfer pipes of the preceding embodiments is enhanced heat exchange, firstly by virtue of a smaller distance and secondly by virtue of an enlarged heat exchange area. Another benefit is a more efficient utilization of the required space and a general enhancement of heat exchange, as well as a versatile use of heat sources and cooling sources in a single container.

In a preferred embodiment of the invention, the heat transfer pipe, one or several, can be divided in parallel into smaller heat transfer pipes. A single heat transfer pipe can be divided into 1-10 smaller heat transfer pipes, which extend in the container for conveying heat and merge into a single larger pipe. Preferably, the heat transfer pipes divide into smaller heat transfer pipes over a section thereof extending inside the container and merge inside the container again into a larger pipe. The heat transfer pipes may also divide upstream of the container inlet and may also divide downstream of the container outlet.

Preferably, a single heat transfer pipe divides into 2-6 smaller pipes, the heat transfer pipe dividing optimally into 3-5 smaller pipes for achieving best possible heat transfer and heat exchange. Preferably, the divided pipes extend inside a spiral made up by the spiral-shaped wastewater pipe.

In a preferred embodiment of the invention, the divided heat transfer pipes, which extend inside a spiral made up by the spiral-shaped wastewater pipe, are adapted to extend at least over a part of the length thereof in a spiral fashion the middle of the spiral made up by the spiral-shaped wastewater pipe. A benefit of this is enhanced heat transfer and enhanced heat exchange and an enlarged heat exchange area. In a preferred embodiment of the invention, the flow direction of wastewater in the container's wastewater pipe is adapted to be opposite to the flow direction of a heat transfer fluid in the container. The opposite flow direction further enhances heat exchange. The containers heat transfer fluid may flow in a vacant interior of the container or in a separate pipe inside the container. In one preferred embodiment of the invention, a first outlet for the wastewater discharge pipe is disposed at a higher level than a first inlet for the wastewater supply pipe, whereby the wastewater traveling in a wastewater pipe within the container's interior is adapted to proceed from the bottom upwards as regarded relative to the working direction of gravity, preferably in response to either a gravitationally established hydrostatic pressure or as a result of pumping. Since the wastewater is set to flow from the bottom upwards, the heat exchange and thereby also the recovery of heat will be enhanced as the heat exchange / or recovery time becomes longer. The invention will now be described even in more detail with reference to the accompanying figures, in which: Fig. 1 is a longitudinal section view, showing a container inside which extend two spiral-shaped pipes running close to each other and intended for wastewater as well as for a heat transfer fluid; Fig. 2 is likewise a longitudinal section view, showing another container inside which extends a spiral-shaped wastewater pipe and in whose interior circulates the heat recovery fluid of a heat pump;

Fig. 3 is a longitudinal section view, showing another container inside which extends a spiral-shaped wastewater pipe and in whose interior circulates the heat transfer fluid of a cooling system.

Fig. 1 shows one embodiment of the invention, wherein a container 1 is cylindrical, the container's outer jacket 12 comprising a side wall 1 ; 1a, which is annular in cross-section and vertical and which is left between the container's horizontal cover 1 ; 1 b and horizontal bottom 1 , 1 c. The container 1 is otherwise closed except that its cover 1 ; 1 b is provided with an inlet 21 for a supply pipe 2a of wastewater 200 arriving in the container 1 , and the container's bottom 1 ; 1 c is in turn provided with an outlet 22 for a discharge pipe 2; 2b of wastewater 200 departing from the container. Between the inlet 21 for the wastewater supply pipe 2; 2a and the outlet 22 for the wastewater discharge pipe 2; 2b, in an interior 10 of the container, extends a continuous wastewater pipe 2; 2c which is provided in a spiral configuration for increasing the heat transfer area. A median line L of the wastewater pipe is denoted in the figure with a dashed line. In addition, through a lower part of the side wall 1 ; 1 a of the closed container's jacket is adapted to extend an inlet 31 by way of which passes a supply pipe 3; 3a for a heat transfer fluid 300, and through an upper part of the side wall 1 ; 1 a of the container's jacket is adapted to extend an outlet 31 by way of which passes a discharge pipe 3; 3b for the heat transfer fluid 300. Between the heat transfer fluid supply pipe's inlet 31 and discharge pipe's outlet 32 is disposed a spiral-shaped heat transfer fluid conveying pipe 3; 3c. The conveying pipe has its median line denoted in fig. 3 with a symbol N and, in general sense, the median line of the conveying pipe 3; 3c is co-directional with the median line L of the wastewater pipe 2; 2c, running at a specific distance from the latter. The heat transfer fluid 300 suitably consists of service water, which travels in a spiral-shaped service water preheating pipe, I.e. in the conveying pipe 3; 3c, such as in a service water preheating coil, in the container ^' s interior 10. The spiral-shape preheating pipe 3; 3c for the service water 300 traces the spiral-shaped wastewater pipe 2; 2c at least over a part of the wastewater pipe's length with a very small distance between the preheating pipe 3; 3c and the wastewater pipe 2; 2c. The spiral-shaped preheating pipe may be in a direct connection with the wastewater spiral or in a specific separate structure on an inner periphery of the wastewater spiral.

Wastewater travels in the container's 1 interior 10 from the inlet 21 to the outlet 22, i.e. its flow direction runs from the top downwards in the spiral-shaped wastewater pipe 2; 2c extending inside the container. The average wastewater flow direction is parallel to the wastewater pipe ^' s median line L, i.e. in this case vertical or roughly longitudinal relative to the container 1. The service water 300 flowing inside the spiral-shaped conveying pipe 3; 3c in turn travels in the container's interior 10 primarily in a direction countercurrent to the flow direction of the wastewater 200 and its average flow direction is parallel to the conveying pipe's median line N.

The wastewater supply pipe's inlet 21 can be included either in the cover 1 ; 1 b or in an upper part of the vertical wall 1a of the jacket 12, and the wastewater discharge pipe's outlet 22 is located either in the bottom 1 ; 1 c or in a lower part of the vertical wall 1 a of the jacket 12.

In one preferred embodiment of the invention, the implementation of a container shown in fig. 1 is not provided with inlets or outlets for a heat transfer fluid 300, 400, 500, but the spiral-shaped wastewater pipe 2; 2c, and the warm service water preheating coil 3; 3c tracing along the same, are adapted to be surrounded by a fluid, such as water. Preferably, the container's interior 10 is adapted to contain a heat transfer fluid 300, 400, 500, especially an aqueous fluid, which encloses to the extent of 70-100 percent the spiral-shaped wastewater pipe 2; 2c and the service water preheating coil 3; 3c extending in the container ^' s vacant interior 10. in fig. 1 there is further denoted an optional inlet 41 and outlet 42 for a second heat transfer fluid, particularly for cooling fluid or refrigerant 400 traveling in a heat pump-equipped building cooling system. The warmed-up refrigerant 400 is intended to be cooled by means of wastewater 200 present in the container's interior at a lower temperature and traveling in the wastewater pipe 2; 2c. The refrigerant 400 has its flow direction in the container's interior primarily counterclockwise relative to the wastewater flow direction, thereby releasing thermal energy to wastewater 200 traveling inside the wastewater pipe. The warmed-up wastewater 200 in turn releases energy to service water traveling in the service water preheating coil (conveying pipe) 3; 3c, said coil extending for the most part alongside the spiral-shaped wastewater pipe 2; 2c. Preferably, the conveying pipe 3; 3c and the wastewater pipe extend sufficiently close to each other for enabling heat to transfer by conduction from the wastewater pipe 2; 2c to the conveying pipe 3; 3c.

Additionally visible in fig. 1 is an inner jacket 1 1 , indicated by a dashed line, which extends inside the outer jacket 12 of the container 1 and complies with its overall shape. If provided with a double jacket 1 1 , 12, it is possible to employ the container as a pressure vessel, in which case the heat transfer fluid 300, 400, 500 present in the interior 10 surrounded by the inner jacket 1 1 can be pressurized. Alternatively, the pressurized heat transfer fluid 400 can be conducted into a space between the outer jacket 12 and the inner jacket. It is also conceivable that around the wastewater pipe 3; 3c, in the container's interior 10 confined by the inner jacket, be provided a water jacket which is heated with the energy of wastewater 200 traveling in the wastewater pipe 2; 2c or some other water flow of a relatively low temperature, such as the water flow used for condensation. In fig. 2 there is illustrated an embodiment of the invention, in which the container 1 , in terms of its shape, is similar to that of fig. 1 and has also an inlet and outlet 21 , 22 of wastewater 200 for the wastewater supply pipe and discharge pipe 2a, 2b similar to those in the container depicted in fig. 1. The container of fig. 2 differs from that of fig. 1 principally by not having a separate preheating coil 3; 3c for warm service water 300 in the container's interior 10, but, instead, flowing in the containers interior 10 is only a heat recovery fluid 500 for the primary loop of a heating system 6 equipped with a heat pump 6. The heat recovery fluid 500 warms up in response to thermal energy released by the wastewater pipe 2; 2c extending inside the container, and delivers heat in a per se conventional manner to a liquid refrigerant 600 arriving in an evaporator H of the heat pump 6. The heat recovery fluid 50 travels for the most part in a countercurrent direction, i.e. from a lower level upwards, with respect to the flow direction of a fluid 200 traveling in the wastewater pipe 3; 3c, thus proceeding in the container's interior 10 from an inlet 51 of a heat recovery fluid supply pipe 5a to an outlet 52 of a heat recovery fluid discharge pipe 5b. The iniet 51 is located in a lower part of a side wall 1 a of the container's jacket and the outlet is located in an upper part of the side wall. The aqueous fluid, such as black or grey wastewater 200, traveling in the wastewater pipe 2; 2c, flows preferably gravitationally from an inlet 21 of a wastewater supply pipe 2; 2a present in an upper part of the container to an outlet 22 of a wastewater discharge pipe 2; 2b, but it is also possible to employ a forced circulation of wastewater, whereby the inlet 21 is preceded by a pump station for the pumping of fluid 200 into the container 1.

As can be noted from fig. 2, the pipe system for a heat recovery fluid is also provided with a three-way valve 53, which can be used to block the passage of heat recovery fluid 500 into the container 1 in the event that the wastewater 200 draining into the container has an excessively low temperature.

The heat recovery fluid 500 travels either solely in the container or, alternatively, in the container as well as in a geothermal, rock or waterway loop associated with the container circulation. Fig. 3 shows an embodiment of the invention, depicting a container 1 otherwise similar to that of fig. 1 except that in the container's interior 10 is now adapted to circulate a condenser loop refrigerant (cooling fluid) 400.

The cooling fluid 400 travels for the most part in a direction co-current with respect to fluid 200 traveling in a wastewater pipe 3; 3a, thus proceeding in the container's interior 10 from an inlet 41 of a cooling fluid supply pipe 4; 4a to an outlet 42 of a cooling fluid discharge pipe 4; 4b.

Between the inlet 41 for the supply pipe 4; 4a of a heat transfer fluid (refrigerant, cooling fluid) 410 arriving in the container as well as the outlet 42 for the discharge pipe 4; 4b of a heat transfer fluid (refrigerant, cooling fluid) 420 departing from the container is established a fluid communication through a cooling fluid 430 flowing in the container's vacant space 10. The inlet 21 for the wastewater supply pipe is located in a cover 1 b of the container's jacket 12 and the outlet 22 for the discharge pipe in a bottom 1 c of the jacket 12. The cooling fluid 430 flows for the most part in a direction co-current with respect to the average flow direction of wastewater 200 flowing in a wastewater pipe 2; 2c in the container's interior 10. The inlet 41 for the cooling fluid supply pipe 4; 4a is located in an upper part 4a of a vertical wall 1 a of the container's jacket 12 and the outlet 42 for the discharge pipe is located in a position lower than the inlet 41 preferably in a lower part of the vertical wall 1 a of the container's jacket 12. This embodiment of the invention provides the benefit of enabling the temperature of refrigerant 400 traveling in a heating system s condenser loop to be reduced with the heat of a wastewater flow 200; 230 traveling in the container's interior, and thereby enabling to reduce the required refrigerant compressor performance and to increase the overall heat pump performance (COP).

The fluid 200 traveling in the wastewater pipe 2; 2c flow preferably gravitationally the same way as in the containers of figs. 1 and 2. Thus, the fluid 200 flows from the iniet 21 of the wastewater supply pipe 2; 2a, located in the cover 1 b of the container's 1 jacket, to the outlet 22 of the wastewater line discharge pipe 2; 2b, which is located in the bottom 1 c of the container's jacket. In this case, as well, it is possible to employ a forced circulation of wastewater by providing a pump station in connection with the supply pipe 2a of wastewater 200. Next follows a further review of a few important aspects relating to the invention.

What has been shown in figs. 1 -3 is thus a general view of a container 1 according to the invention for heating wastewater 200 or recovering its thermal energy, said container 1 comprising a first inlet 21 for a supply pipe 2a of the wastewater 200 and a first outlet 22 for a wastewater discharge pipe. A wastewater pipe 2; 2c extending between the inlet 21 of the wastewater supply pipe and the outlet 22, within an interior 10 of the container, is continuous and constructed in a spiral shape, and that the container further comprises at least one second inlet 31 , 41 , 51 for a supply pipe 3a, 4a, 5a of a heat transfer fluid 300, 400, 500 arriving in the container as well as at least one second outlet 32, 42, 52, 52 for a discharge pipe 3b, 4b, 5b of a heat transfer fluid 300, 400, 500 departing from the container, whereby the heat transfer fluid 300; 330, 400; 430, 500; 530 provided in the container's interior 10 is adapted either to recover thermal energy of wastewater 200; 230 traveling in the wastewater pipe 2; 2c installed in the container's vacant interior 10 or to release thermal energy to wastewater 200; 230 traveling in the wastewater pipe 2; 2c installed in the container's vacant interior 10.

When the heat transfer fluid 300, 400, 500 consists of a cooling fluid 400 traveling in a building cooling system 4, it will be condensed in a vacant interior 10; 10a of the container. The cooling fluid 400 flows within the interior in a direction countercurrent to the average top-down wastewater flow direction (L), the cooling fluid flowing thereby upwards in a vertical direction of the container 1 , while taking up wastewater thermal energy at the same time. Alternatively, the service water 300 can also be heated in the container's vacant interior 10; 10a the same way as the cooling fluid 400. The service water 300 is adapted to flow within the interior 10; 10a in a direction countercurrent to the average top-down wastewater flow direction (L), while taking up at the same time thermal energy of the wastewater 200; 230 flowing in the wastewater pipe 2; 2c. it is possible to employ a container of the invention, among other things, in residential buildings, particularly apartment buildings, hotels and commercial properties. According to the inventors' estimate, among other things, the consumption of thermal energy in apartment buildings can be reduced by about 10% by conducting wastewaters across a container according to the invention.

The temperature of wastewater arriving in the container 1 is generally about 20- 30°C and that of departing wastewater is 5-10°C. If the temperature of wastewater departing from the container is lower, the circulation of a heat transfer fluid in the preheating coil 3c or in the container's interior must generally be discontinued by means of a valve installed in the heat transfer fluid piping system as illustrated in fig. 2.

Materials employed for the service water preheating coil 3c as well as for the spiral-shaped wastewater pipe 2c are generally a plastic or metal with a high resistance to chemicals and a high thermal conductivity. On the other hand, the aforementioned use of the container involves important aspects as set forth in the following viewpoints:

1. Wastewater 200 is conducted to a spiral-shaped continuous wastewater pipe 2; 2c, present in an interior 10 of the container, by way of a supply pipe's 2a inlet 21 and, in addition, a heat transfer fluid is conducted into the container's interior by way of at least one second inlet 31 , 41 , 51 so as to enable a heat transfer fluid 300; 330, 400; 430, 500; 530 either to take up thermal energy of wastewater 200; 230 traveling in the wastewater pipe 2; 2c installed in the container's vacant interior 10 or to release thermal energy to wastewater 200; 230 traveling in the wastewater pipe 2; 2c installed in the container's vacant interior 10.

2. An aspect of viewpoint 1 , wherein the heat transfer fluid 300, 400, 500 coOnducted into the container's interior 10 is adapted to surround to the extent of 70-100 percent the spiral-shaped wastewater pipe 2; 2c extending container's vacant interior 10.

3. An aspect of viewpoint 1 or 2, wherein between the heat transfer fluid 300 arriving in the container as well as the heat transfer fluid departing from the container is established a fluid communication through a heat transfer fluid 430, 530 present in the container's vacant interior 10; 10a.

4. An aspect according to any of the preceding viewpoints, wherein the heat transfer fluid 300, 400, 500 is a heat recovery fluid 500 traveling in or being in a fluid communication with a heat pump's primary loop 5, whereby the heat recovery fluid 500 travels in a direction countercurrent to an average traveling direction L of the wastewater 200 in the container's interior 10, thus taking up thermal energy from the wastewater 200 traveling in the wastewater pipe 2; 2c.

5. An aspect according to any of the preceding viewpoints 1 -3, wherein the heat transfer fluid 300, 400, 500 is a heating or particularly cooling fluid 400 traveling in a building heating or particularly cooling system, whereby particularly the cooling fluid 400 travels in a direction countercurrent to an average traveling direction of the wastewater 200 in the container's interior 10, thus releasing thermal energy to the wastewater 200 traveling in the wastewater pipe 2; 2c.

6. An aspect according to any of the preceding viewpoints 1 -4, wherein between an inlet (31 ) for a supply pipe 3a of the heat transfer fluid 300 arriving in the container 1 as well as an outlet (32) for a discharge pipe (3b) of the heat transfer fluid 300 departing from the container is provided a continuous spiral-shaped heat transfer pipe 3; 3c, which traces along an outer surface of the spiral-shaped wastewater pipe 2; 2c at least over a part of the heat transfer pipe's 3; 3c length, and the heat transfer fluid 300; 330 is adapted to take up thermal energy of the wastewater 200; 230 traveling inside the wastewater pipe 2; 2c installed in the container's vacant interior 10; 10a or thermal energy of the cooling fluid 400 traveling in a building cooling system, by working out the relative temperatures of the heat transfer fluid 300; 330 and the wastewater 200; 230 to become suitable for each other.

7. An aspect according to any of the preceding viewpoints, wherein the container 1 is capable of being supplied by way of a continuous spiral-shaped heat transfer pipe with a heat transfer fluid, such as a gas, which is heated with wastewater flowing in the continuous spiral-shaped heat transfer pipe 3; 3c or with thermal energy of the cooling fluid 400 traveling in a building cooling system.

8. An aspect according to any of the preceding viewpoints, wherein the container 1 has its first outlet 22 for a wastewater discharge pipe disposed at a higher level than its first inlet 21 for a wastewater supply pipe, whereby the wastewater traveling in the container's interior 10 in the wastewater pipe 2; 2c is adapted to proceed from the bottom upwards as regarded in terms of the working direction of gravity, preferably either in response to a gravitationally generated hydrostatic pressure or as a result of pumping.

9. An aspect according to any of the preceding viewpoints, wherein the heat transfer fluid 400, 500 is a refrigerant (cooling fluid 400) for a condenser loop or a heat recovery fluid 500 for a heat pump's primary loop 5 or a heat recovery fluid 500 in a fluid communication therewith, which is in a heat transfer communication with a cooling source preferably present in a geothermal, rock or waterway loop associated with the container loop and having a temperature lower than that of the wastewater 200; 230 present in the wastewater pipe, and preferably the cooling source is a passive cooling source, preferably a drilled water well or a geothermal heat pump's cooling loop.

10. An aspect according to any of the preceding viewpoints, comprising a container 1 for recovering thermal energy of wastewater 200, said container being further provided with at least one second inlet 51 for a supply pipe 3a, 4a, 5a of a heat transfer fluid 300, 330, 400, 430, 500; 530 capable of being supplied into the container, as well as with at least one second outlet 32, 42, 52 for a discharge pipe 3b, 4b, 5b of a heat transfer fluid 300, 330, 400, 430, 500; 530 capable of being removed from the container, such that between the inlet 31 as well as the outlet 32 is provided a continuous spiral-shaped heat transfer pipe (3; 3c), which traces along an outer surface of the spiral-shaped wastewater pipe (2; 2c) at least over a part of the heat transfer pipe's (3; 3c) length, and that the heat transfer fluid (300; 330, 400, 430, 500; 530) is adapted to take up thermal energy of the wastewater 200; 230 traveling inside the wastewater pipe (2; 2c), and that the heat transfer fluid is one of the following: a refrigerant (cooling fluid (400) for a condenser loop or a heating or cooling fluid (400) or service water (300) for a building or a heat recovery fluid (500) for a heat pump's primary loop (5).