Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND DISTRIBUTION TANK FOR LOW-ENERGY NETWORK
BACKGROUND OF THE INVENTION
[0001] The invention relates to the utilization of low energy, such as
geothermal heat, and particularly to a system for transferring heat with a
termi-
nal, such as a heat pump or the like, from the earth or water via a transfer
me-
dium.
[0002] In present practice, the utilization of low energy obtained
from the earth, water or rock refers to heating of a building and service
water
by means of a pump and a heat collector circuit. The operating principle of
such a geothermal heat system corresponds to that of a freezer, but is
reverse:
the system cools the earth and heats a water accumulator, for example. Often
2 to 3 units of heat are obtained per electric energy unit employed. The per-
formance is significantly better than in direct electric heating. The
consumption
of heating energy in properties is significant under cold weather conditions.
The utilization of geothermal heat is increasingly cost-effective as the costs
of
electricity and oil continue to rise.
[0003] Alternatively, a geothermal heat pump system may be util-
ized also for cooling interiors, for example by circulating a cool solution
from
the earth through a cooler located in the incoming airflow.
[0004] A common manner of heat recovery is a pipework located
horizontally at a depth of 1 to 1.2 metres. However, such a pipework requires
a
wide surface area, which renders it usable only in large plots of land. The
col-
lector circuit may be located in the ground or in water. The placement of a
horizontal pipework in the ground requires that a pipe ditch be dug in the
entire
area of the collector circuit. The pipe loops of the circuit have to be at a
dis-
tance of at least 1.5 metres from each other in order for adjacent loops not
to
interfere with each other's heat recovery. The placement of a horizontal pipe
in
a park, for example, is difficult without harming plants and roots of trees.
[0005] A thermal well is another common manner of heat recovery.
It involves the immersion of a pipework into a hole drilled in a rock. A
thermal
well, i.e. a drilled well, is usually drilled vertically. Very little surface
area is re-
quired for a thermal well compared with a horizontal pipework. However, a sig-
nificant layer of loose ground may exist on top of the rock. The loose ground
has to be provided with a protecting tube, which raises costs. Accordingly,
ground having a thick layer of loose ground, restricts the placement of a ther-
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mal well. Heat yield in a thermal well is usually higher than in a horizontal
pipework. Heat yield from a thermal well partly depends on the flow of ground-
water. However, it is impossible to estimate the flow of groundwater without
implementing expensive drilling.
[0006] A third manner of heat recovery is to place a heat collector
pipework at the bottom of a lake or other waterway, whereby heat is trans-
ferred from the bottom sediment and water to a transfer solution. The pipe may
be transported to the water in the ground, but in that case, separate trenches
should exist for the inlet and outlet pipes. A pipework located in water is
easy
to install at the bottom of a waterway. However, a pipe filled with solution
is
lighter than water, and therefore tends to rise upwards. Risen pipe sections
may cause air pockets that interfere with the circulation. Accordingly, the
pipe
has to be anchored to the bottom with the use of a sufficient number of
weights. A pipework placed at the bottom is also always susceptible to dam-
age. An anchor of a boat or the like may engage the pipework and damage the
pipe. At the water line, the inlet and outlet pipes have to be buried into the
bot-
tom in order for ice not to break the pipework.
[0007] The selection between these three manners depends on the
location, area and ground of the available area. Previously, the aim was to im-
plement geothermal networks in such a manner that several houses share one
common, larger heat collector circuit. However, to connect several properties
to such a system requires a corresponding extension of the heat collector cir-
cuit.
BRIEF DESCRIPTION OF THE INVENTION
[0008] An object of the invention is thus to provide a system for a
low-energy network and a distribution tank for the system in a manner allowing
the above problems to be solved. The object of the invention is achieved with
a
system and a distribution tank that are characterized in what is stated in the
independent claims. Preferred embodiments of the invention are described in
the dependent claims.
[0009] The invention is based on interconnecting the distribution
tanks of a low-energy network with a main pipework and on optionally connect-
ing ground circuits and heating circuits via a terminal to the distribution
tanks
according to the need. In each location, the ground circuits may be imple-
mented in a suitable manner. Accordingly, the ground circuit may also be lo-
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cated at the bottom of a waterway. In addition, the system is expandable or,
alternatively, heating circuits or ground circuits can be removed therefrom or
closed without restricting the operation of the rest of the system sections.
[0010] An aspect of the invention is to provide a system for imple-
menting a low-energy network.
[0011] Another aspect of the invention is to provide a distribution
tank for a low-energy network.
[0012] In accordance with an embodiment of an aspect of the inven-
tion, the system comprises a collector circuit filled with a first transfer
solution,
a heat transfer circuit filled with a second transfer solution, and a terminal
adapted to transfer heat between the transfer solutions of the.collector
circuit
and the heat transfer circuit, wherein the collector circuits are connected to
the
terminal via two distribution reservoirs, of which the first distribution
reservoir is
isolated and configured to receive and transfer heated transfer liquid, and
the
second distribution reservoir is configured to receive and transfer cooled
trans-
fer liquid, and at least one collector circuit connecting the first
distribution res-
ervoir and the second distribution reservoir is connected to each distribution
reservoir terminating the low-energy network. Herein, a terminating
distribution
reservoir refers to a reservoir from which the network starts or to which it
ends.
The network of the invention does not limit the shape and routes of the net-
work. The network may be implemented in circuit form, whereby the network
starts and ends at the same terminating distribution reservoir. Similarly, the
network of the invention may be stellate, whereby there are several
terminating
distribution reservoirs. An advantage of the invention is that the network may
be expanded without restrictions. For example, a network extension may be
connected by means of a main pipework and distribution reservoirs to any dis-
tribution reservoir of a network implemented in circuit form. In this case,
the
distribution reservoirs separate from the circuit serve as terminating
distribution
reservoirs.
[0013] In accordance with an embodiment, first distribution reser-
voirs and second distribution reservoirs are interconnected in the
distribution
tank. The distribution reservoirs are arranged in the distribution tank in
such a
manner that an isolation section for decreasing heat transfer between the res-
ervoirs is arranged between the distribution reservoirs.
[0014] The distribution tanks are connected with a first main pipe for
transferring transfer solution cooled with a terminal, such as a geothermal
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pump or the like, and with a second main pipe for transferring transfer
solution
heated in the ground circuit. The first main pipe can be isolated, allowing
main
pipes to be placed in each other's vicinity without any significant heat
transfer
therebetween. The thickness of the isolation of the first main pipe may be in-
creased or decreased depending on the installation depths of the main pipes
or the distance therebetween. Preferably, the main pipes may be placed in the
same dug ditch on top of each other, which eliminates the need to dig separate
ditches. The depth of placement of the main pipes may vary, but it may be 1 to
2 metres, for example, allowing a non-isolated main pipe to receive heat from
the ground.
[0015] The second main pipe is non-isolated in a manner allowing
thermal energy to transfer between the transfer liquid in the pipe and the
ground outside the pipe. This being so, the main pipes also serve as part of
the
collector circuits that may be utilized for both heating and cooling of
properties.
[0016] In accordance with an embodiment of the invention, each
ground circuit connected to a distribution tank is provided with measuring
means and adjusting means in a manner enabling the measurement of the
heat production of each collector circuit with the measuring means and the
flow
rate of each collector circuit is separately adjustable with the adjusting
means
to conform with the requirement of the terminals. This enables of the use of a
control system for electric control of the adjusting means of the distribution
tank. The connection of the adjusting means and measuring means of the dis-
tribution tank to the control system may be not only a wired connection, but
also a wireless data communication connection. A wireless connection to the
control system may facilitate the implementation of the system, in connection
with expansion of the system, for example.
[0017] The control system enables the restriction of the flow of the
different collector circuits such that transfer liquid is obtained to the
terminal
from the most advantageous collector circuit or collector circuits. In other
words, the control system is used to adjust the flow rates of the collector
cir-
cuits in a manner allowing the temperature of the transfer liquid to be set to
a
level wherein the performance of the terminals is maximally high. In this
case,
one terminal may utilize other collector circuits connected to the system in
ad-
dition to or instead of its 'own' collector circuit.
[0018] Separate collector circuits cannot be positioned on all prop-
erties. In the solution of the invention, such properties may also be
connected
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to the system through terminals. A measuring apparatus connected to the ter-
minals may be used as billing basis. An advantage of the invention is
explicitly
that the flow of the collector circuits may be implemented by means of termi-
nals, without a separate pump. When all terminals are closed, the flow stops
and the temperature of the transfer liquid settles to correspond to the
tempera-
ture of the surrounding ground or water. However, it is possible to provide
lar-
ger systems, for example, with a separate pump.
[0019] Consequently, it is to be noted that the network may be pro-
vided with distribution tanks without a single ground circuit. Such a
situation
may arise for instance in the case of a multi-storey building, wherein several
heat circuits of properties are connected to one distribution tank, and the
ground circuits are implemented at a near-by field area or below a park, for
example.
[0020] However, at least one ground circuit is connected to each
terminating distribution tank of a low-energy network in order for the
transfer
solution to be transferred from the main pipe to another without directly
mixing
cooled and warmed liquids. The ground circuit may be selected according to
the location of the distribution tank. For example, the ground circuit may be
a
horizontal circuit, a vertical or obliquely downwards directed pipe having an
outer and an inner pipe, a thermal well drilled in rock or a pipework placed
in a
waterway. One or more ground circuits may be placed in one distribution tank
in accordance with the location and the ground.
[0021] In accordance with another aspect of the invention, a distri-
bution tank for a low-energy network comprises two reservoirs, a first
reservoir
and a second reservoir, of which the first reservoir is intended to receive
and
transfer heated transfer liquid and the second reservoir is intended to
receive
and transfer cooled transfer liquid. The reservoirs are provided with main
pipe
receiving means for receiving the main pipes into a first and a second space,
respectively, and receiving means for ground circuits and/or terminal pipe-
works for receiving the pipeworks into a first and a second space,
respectively.
The number of ground circuit and/or terminal receiving means may vary. A dis-
tribution tank may be prepared for connection under factory conditions, and
therefore it would be advantageous to reserve extra connection points for pos-
sible network extensions or changes.
[0022] An isolation section separates the first reservoir from the
second reservoir. The isolation section serves to minimize heat transfer be-
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tween cold liquid and liquid heated in a ground circuit. The first and second
reservoirs of the distribution tank preferably have a volume that stores
liquid in
the reservoir. The distribution reservoirs equalize the flow in the pipeworks
and
enable an even flow control for each pipe originating from the distribution
res-
ervoir.
BRIEF DESCRIPTION OF THE FIGURES
[0023] In the following, the invention will be described in more detail
in connection with preferred embodiments with reference to the accompanying
drawings, in which
Figure 1 schematically shows an embodiment of the system of the
present invention;
Figure 2 shows a second embodiment of the system of the present
invention;
Figure 3 shows a third embodiment of the system of the present in-
vention;
Figure 4 shows a front view of an embodiment of the distribution
tank of the present invention;
Figure 5 shows a front view of a second embodiment of the distribu-
tion tank of the present invention;
Figure 6 shows a top view of the second embodiment of the distribu-
tion tank of the present invention;
Figure 7 is a partial view of an embodiment of an end part of a pipe
to be connected to a distribution tank of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] Referring to Figure 1, wherein an embodiment of the system
according to the present invention is shown, a pipe 1 a comprising an inner
and
an outer tube is located obliquely below ground level, a second collector tube
1 b being a pipe constituting a one-piece circuit. A terminal 3 utilizes the
low
energy accumulated in the pipework 1 a and 1 b, and transfers it to a house 2
via a transfer pipe 41, wherein it circulates via a heating circuit 7 and
returns
via a transfer pipe 42 to the collector pipework 1 a, lb. The number, length,
inclination etc. of the pipes 1 a, 1 b may vary in accordance with the energy
re-
quirement and/or ground.
[0025] The terminal 3 may be a geothermal pump, for example. The
terminal 3 is connected to the collector circuits 1 a and 1 b via distribution
tanks
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80. The collector circuits 7 are connected to the terminal 3 via two
distribution
reservoirs 82, 81. The first distribution reservoir 81 is isolated and
configured
to receive and transfer heated transfer liquid, the second distribution
reservoir
82 being configured to receive and transfer cooled transfer medium. One col-
lector circuit 1 a, 1 b for connecting the first distribution reservoir 81 and
the
second distribution reservoir 82 is connected to each distribution reservoir
ter-
minating the low-energy network. Thus, the transfer solution may be trans-
ferred from one main pipe to another without direct mixing of the cooled and
heated liquid. Figure 1 only shows two distribution tanks 80, but it is
obvious
that the system may comprise a plurality of distribution tanks 80. This being
so,
distribution tanks having no collector circuits can be placed between the
termi-
nating distribution tanks 80 of the system, such tanks having connected
thereto
not only main pipes 100, 200, but also transfer pipes 41, 42 to the terminals
of
the properties. An applicable connecting manner also allows the direct connec-
tion (not shown) of the transfer pipe of one house 2, for example, to the main
pipes 100, 200.
[0026] Figure 2 shows a second embodiment of the system accord-
ing to the present invention. The terminals 3 of two houses 2 are connected to
the distribution tank 80 located on the left, the terminal 3 of one house 2
being
connected to the distribution tank located on the right. The flow in the
collector
pipes connected to the distribution tanks 80 is controlled with a control
system
50. In the case of heating, wherein for instance the terminal 3 starts and
when
the transfer liquid of collector circuit 1 b is warmer than the liquid of
collector
circuit 1 a, the control system is able to restrict the flow of collector
circuit 1 a
and increase the flow of collector circuit 1 b such that the terminal is able
to
receive transfer liquid that is as warm as is preferable in view of
performance.
In the case of cooling, the situation is naturally reversed.
[0027] The control system 50 includes preset data for each collector
circuit connected thereto and is able to use the data to restrict or increase
the
flow of each collector circuit to achieve the desired end temperature. In addi-
tion, the temperature of the transfer liquid returning from the collector pipe
is
measured with measuring means, in response to which the control system is
able to perform an adjustment. For example, the control system may have in-
formation on the lengths of the main pipes, allowing it to also take into
account
a change in the temperature occurring in the main pipe.
[0028] Figure 3 shows a third embodiment of the system according
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to the present invention, wherein the control system 50 is connected to one
distribution tank by a wired connection and to another distribution tank 80 by
a
wireless connection. In the case of the wireless connection, the control
system
50 and the distribution tank are provided with appropriate transmission and
reception means 51 a, 51 b. The control system 50 is preferably connected to
an information network, such as the Internet. This enables remote monitoring
and control of the system.
[0029] Figure 4 shows a front view of an embodiment of the distribu-
tion tank according to the present invention. The distribution tank 80
comprises
a first reservoir 81 and a second reservoir 82, of which the first reservoir
81 is
intended to receive and transfer heated transfer liquid, the second reservoir
82
being intended to receive and transfer cooled transfer liquid. The reservoirs
comprise main pipe receiving means 110, 210 for receiving the main pipes
100, 200 to the first and second distribution reservoir 81, 82, respectively.
In
this embodiment, the main pipe receiving means 110, 210 are tubular sections
that project from the distribution tank 80 and to which the main pipes 100,
200
may be connected in an appropriate manner, by welding, for example. The
figure further shows ground circuit and/or terminal pipe receiving means 11,
12
for receiving the pipeworks in the first and second space 81, 82,
respectively.
The figure only shows one pair of each receiving means, but it is evident that
their number may vary.
[0030] When the receiving means 11, 12, 110, 120 are manufac-
tured such that their ends are closed before installation, their number may be
set larger, taking into account a possible expansion of the system. In this
case,
it would be preferable to reserve at least one extra pair of main pipe
receiving
means 110, 120 in each distribution tank. The first reservoir 81 and second
reservoir 82 of the distribution tank 80 are separated with an isolation
section
86. The figures show an embodiment, wherein the distribution tank is round
when observed from above, the distribution reservoirs therein being semicir-
cles. However, it is evident that both the distribution tank and the
reservoirs
therein may be of different shapes. For example, the distribution reservoirs
may be placed on top of each other, allowing also them to have a cylindrical
shape. It is also possible to place the distribution reservoirs separately,
for ex-
ample in larger systems, wherein the number of pipes to be connected is large.
[0031] Figure 5 shows a front view of the second embodiment of the
distribution tank according to the present invention. The distribution tank 80
is
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provided with measuring means 83 and adjusting means 85. In this embodi-
ment, the measuring means 83 are placed in the receiving means 11 of the
pipeworks of the ground circuits, and the adjusting means 85 to the receiving
means 12 of the pipework of the ground circuits. However, the location of the
measuring means 83 and the adjusting means 85 may vary for instance such
that they are located at the same point. Two arrows show the transfer of heat
from the ground to the second, non-isolated distribution reservoir 82. The sys-
tem may further comprise shutoff means (not shown), by means of which one
or more network section may be separated for the duration of repair or expan-
sion of the network, for example.
[0032] Figure 6 shows a top view of the second embodiment.of the
distribution tank according to the present invention. The isolation section 86
is
placed between the first distribution reservoir 81 and the second distribution
reservoir 82.
[0033] Figure 7 is a partial view of an embodiment of the end sec-
tion of the pipe 1 a (shown in Figures 1 to 3) to be connected to a
distribution
tank according to the present invention. The transfer liquid is transferable
via a
cover part 60 in the pipe 1 to the distribution tank. The cover part 60
comprises
an inner connecting sleeve 61, which is connected inside the pipe 1 to the in-
ner pipe 10, and an outer connecting sleeve 62, with which the transfer liquid
of the outer pipe 20 can be led to a separate pipe. The cover part 60 can be
connected to the pipes to be connected to the distribution tank by
conventional
methods, by welding, for example.
[0034] It is obvious to a person skilled in the art that as technology
advances, the basic idea of the invention can be implemented in a variety of
ways. Consequently, the invention and its embodiments are not restricted to
the above examples, but may vary within the scope of the claims.
