Note: Descriptions are shown in the official language in which they were submitted.
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WO 97l284I2 I PCT/SE97/00153
Regenerative heat recovery unit comprising heat accumulators
tiltably movable to have a valve function
The present invention relates to a heat recovery unit, particularly a heat
recovery unit
having movable heat accumulators.
Heat recovery units are used in. amongst others, ventilation systems for e.g.
venti-
lating buildings and at the same time returning the heat out of the extlaust
air which
is ventilated out from the building to the e:cterior air which is fed into the
building
in the form of inlet air.
A heat recovery assembly which is present on the market has iZVO plate
housings
which each surround their own regenerative plate package which fonts the heat
accumulators. Each plate housing is mutually joined with two valve housings.
Each
valve housing comprises a valve leaf which are each influenced by their own
valve
1 ~ motor. One of the valve housings is equipped with a supply air fan which
is connec-
ted to a supply air channel on the valve housing. and with an e.~chaust air
fan which
is connected to an e,~chaust channel on the valve housing. the valve housing
itself
is connected to each and all of the plate housings via a supply air opening
and
respectively an exhaust air opening on the respective plate housings. The
second valve
housing is equipped with a used-air channel and an exterior air channel and is
connected
?0
to each of the plate housings via a used-air opening and respectively an
exterior air
opening of the respective plate housings.
Exhaust air and respectively exterior air passes alternately through the plate
packages.
When one of the plate packages has warmed up and the other has cooled, the
valve leaves
in the valve housings are switched over, whereby the exhaust and respectively
exterior air
change plate package and have the opposite direction of flow compared with the
air which previousiv flowed in the respective plate packages.
CA 02244064 2005-02-28
2
Another exisnne heat recovery assembly is the rotation heat exchan~er where a
continuous airflow flows through a rotating cylinder. The axis of rotation of
the
cylinder extends into a plane which coincides with a wall. On one side of the
wall,
warm air flows and on the other side cold air flows_ By letting the warm air
pass
through the cylinder, the part of the cylinder which is on the ''waxen" side
is warmed
up. When the cylinder rotates, the warmed up pan of the cylinder will go over
to the
''cold" side. whereby the cold air which flows throu4h the cylinder is warmed
up.
A problem with conventional heat recovery units is the need for a cross-over
valve. In
addition, the arrangement of elements in conventional heat-recovery units can
create
undesirable noise when the ventilation system switches over from exterior air
to exhaust
air or vice-versa.
It is an object of the present invention to obviate or mitigate the problems
associated with
conventional heat recovery units.
The present invention relates to a heat recovery unit comprising a casing
which contains
at Ieast one regenerative heat accumulator, whereby the casing has an inlet
air opening,
an exhaust air opening, an exterior air opening and a used-air opening, and
whereby the
exhaust air and the exterior air alternately pass through the heat
accumulator.
A main object of the present invention is to achieve a heat recovery unit
which
is-cquipped wirii at least one regenerative heat accumulator. which eliminates
the
need of a separate cross-over valve, which controls the e.~chaust air and the
e:~terior
air which pass through the heat accumulators. Preferably two heat accumulators
are coupled together to a heat recovery unit.
Anotr'~er object of the present invention is to provide a heat recovery unit
which has
a very low sound change in the ventilation system when the switching over
occurs
from the exterior air to the exhaust air, and vice versa, in the heat
accumulators.
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2a
A further object of the present invention is to provide possibility of
recirculatory
operation with the heat recovery unit. which recirculates the exhaust,air
through
the supply air opening under special operating conditions.
A further object of the present invention is to provide that the air flows in
the same
to direction through the openings in the casino, irrespective of the direction
of the air
through the heat accumulators.
CA 02244064 2005-02-28
A further object of the present invention is to provide a low pressure drop
across the heat
recovery unit.
A further object of the present invention is to provide a high degree of
temperature exchange in
the heat recovery unit.
A further object of the present invention is to provide a heat recovery unit
which permits simple
cleaning.
According to the invention these objects are achieved by a heat recovery unit
in which the heat
accumulator, by means of a rotating movement, has a valve function which opens
and
respectively closes said openings when the heat accumulator moves from a first
position for
exhaust air throughflow to a second position for exterior air throughflow.
According to an aspect of the present invention there is provided a heat
recovery unit, comprising
a casing, a pair of exhaust airflow openings provided in the casing, a pair of
supply airflow
openings provided in the casing, a regenerative heat accumulator having two
parallel end faces,
the regenerative heat accumulator being housed by the casing, and the
regenerative heat
accumulator rotatable about an axis of rotation perpendicular to a normal
direction of the end
2o faces from a first position in which the end faces cover the pair of
exhaust airflow openings and
leave open the pair of supply airflow openings to a second position in which
the end faces cover
the pair of supply airflow openings and leave open the pair of exhaust airflow
openings.
According to a preferred embodiment the pair of supply airflow openings
comprises a supply air
opening and an exterior air opening.
According to another aspect of the present invention there is provided a heat
recovery assembly
comprising two regenerative heat recovery units as discussed in the previous
paragraph, the
regenerative heat recovery units being coupled together so that the openings
of the respective heat
3o recovery unit are joined to each other and wherein rotational movements of
the regenerative heat
accumulators are controlled so that when the regenerative heat accumulator in
one of the heat
recover units is in the first position, the regenerative heat accumulator in
the other heat recovery
unit is in the second position and vice versa.
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The invention will be described in more detail below by means of examples of
embodiments with reference to the appended drawings.
Figure 1 shows a perspective view of a heat recovery unit according to a first
embodiment.
Figure 2 shows a view from above of two heat recovery units which are coupled
together to form a heat recovery assembly.
Figure 3 shows a perspective view of a heat recovery unit according to a
second
embodiment.
Figure ~ shows a side view of a heat recovery unit according to the second
embodiment.
Figure ~ shows an example of the application of a heat recovery unit according
to the second embodiment.
Figure 6 shows a side view of a heat recovery unit according to the second
embodiment in a third position.
Figures 7-8 show side views of a heat recovery unit according to a third
embodiment in two different positions.
Figure 1 shows a perspective view of a heat recovery unit according to a first
embodiment. The heat recovery unit comprises a casino 1 which forms a space 2,
which contains a regenerative heat accumulator ~. according to this embodiment
the casing I is elongated with a length which is Greater than its width and
height.
The heat accumulator ~ which is placed inside the casino 1 has a length and a
width
which are somewhat less than the length and width of the space 2 which is
formed
by the casing I so that a clearance is formed betvueen the inner surface of
the casing
1 and the heat accumulator ~. The thickness of the heat accumulator ~ is less
than
the height of the space 2. This allows the heat accumulator ~ to rotate
forwards and
backwards inside the casing I . The swinGing movement takes place as a tipping
movement around a shaft 34 which carries the heat accumulator ~. The shaft 30
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4A
passes through a hole in the casing 1 and is mounted in bearings in the casing
1 on
both sides of the heat accumulator ~. In Fiwre 1 the shaft 30 is imagined to
be
horizontal.
The casing i has ends at which a supple air opening 10, an exhaust air opening
1 ~,
- an e:ctenor air opening 20 and a used-air opening ~~ are arranged. which
each
cooperate with end faces 3~ of the heat accumulator 5. The end faces 35 are
prefer-
ably parallel with the shaft 30 and planar and lie against the inside of the
inner
surfaces of the casing 1 around the openings 10-?~. The supply air opening 10
~d ~e used-air opening 25 and respectively the exhaust air opening 15 and the
exterior
air opening 20 are separated by means of a wall part 27 and respectively 28,
which can be
formed by part of the casing l . In the embodiment shown, both of the end
faces 35 have
sealing strips 36 along their upper and lower edges. In a first position,
shown in
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Figure l, the upper strip 36 of the iefthand end face 3~ seals against the
upper side
of the casino i . and the lower strip against the lower edge of the wall pan ?
8. at the
same time as the upper strip ~6 of the riQhthand end face 3~ seals against the
upper
edge of the wall pan ?7 and its lower strip seals against the inside of the
bottom of
the casing i .
The heat accumulator can be built up from a number of plates 37 (Figure 4)
which form a
plurality of throughflow channels 38 for air. The throughflow channels 38 are
preferably
directed in the direction of the thickness of the heat accumulator S. The
plates 37
consequently form a large heat-absorbing and respectively heat-emitting
surface.
The heat recovery unit can be used in a ventilation system for ventilating a
building,
e.g. an appartment house or an office building. The air which leaves rooms in
the
building by the ventilation is called e:chaust air and the air which is
supplied to the
i ~ rooms is called supply air.
By means of its forwards and backwards rotating movement the heat accumulator
has a
valve function which opens and respectively closes said openings 10-25 when
the heat
accumulator 5 rotates from a first position for exhaust air throughflow to a
second
position for supply air throughflow.
?0
With e,Yhaust air throuahflow. when the heat accumulator ~ is positioned in
the first
position, e:chaust air at room temperature flows in through the e~chaust air
opening
1 ~ and into the space ? in which the heat accumulator ~ is positioned. The
exhaust
?5 air room temperature flows subsequently through the heat accumulator ~ in a
direc-
lion which substantially corresponds to the direction of its thickness. The
heat accu-
mulator ~ is thereby heated up by the throuohflowin~ exhaust air. The exhaust
air
then flows out through the used-air opening 2~ in the form of used air and
subse-
quently leaves the space ? in which the heat accumulator p is placed. The used
air
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WO 97/28412 6 PCT/SE97/00153
which leaves the used-air opening ?5 can subsequently suitabtv flow into a
channel
~2 (Figure ~). which transports the used air out of the building.
A first sensor >j senses the temperature of the used air which leaves the used-
air
openin~ 2~. A reference sensor ~6 can. for e;cample, be placed in the building
which
is to be ventilated. whereby the reference temperature will correspond to the
room
- temperature in the buildin~. The first sensor » and the reference sensor ~6
are
connected to a control unit 60. When the difference between the temperature
which
the first sensor » senses and the temperature which the second sensor ~6
senses
decreases to a predetermined value, the control unit 60 gives a sisal to a
stepping
motor 6?. which is connected to the shaft 30. whereby the motor 63 rotates the
heat
accumulator p to the second position for supply air throughflow_ Instead of a
step-
ping motor it is conceivable to use another power generating means such as a
hydraulic or pneumatic cylinder.
During exterior air throuehflow, exterior air flows in through the exterior
air
opening ?0 and into the space 2 in which the heat accumulator ~ is positioned.
The exterior air then flows throush the heat accumulator p in a direction
which
substantially corresponds to the direction of its thickness. T'he exterior air
is thereby
heated up by the heat accumulator ~ warmed, up by the e.~chaust air. 'ihe air
then
flows out through the supply air openin' I O in the form of supply air and
conse-
quently leaves the space 2 in which the heat accumulator ~ is positioned. The
supply
air which leaves the supply air opening 10 then flows either directly into the
build-
ing or into a duct system (not shown) which distributes the air into the
different
2~ rooms of the building.
A second sensor ~7. which is placed by the supply air opening 10 and connected
to the control unit 60 senses the temperature of the warmed up supply air.
When
the difference between the temperature which the second sensor ~ r senses and
the
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temperature which the reference sensor ~6 senses increases to a predetermined
value, the control unit 60 gives a signal to the stepping motor 62. whereby
the motor
62 tips the heat accumulator ~ to the first position for exhaust air
throuQhflow.
A fan part 6~ which comprises two fans 66.67 (Figure 4) can be connected to
the
supply air opening 10 and the used-air opening 2~. and a filter pan 70 which
comprises twa filters 71,7? can be connected to the e.~chaust air opening 1 ~
and
the exterior air opening 10.
When the heat accumulator ~ is heated up by the exhaust air throu~hflow, the
e~chaust air at room temperature will first meet one side, in Figure 4 the
lower side,
of the heat accumulator ~. This first side of the heat accumulator ~ will have
a
higher temperature than the second side. if the heat accumulator ~ is rotated
to the
second position before the second side of the heat accumulator ~ has been able
to
1 ~ achieve the same temperature as the first side.
According to the first embodiment in Figure 1. the e.Yhaust air and the supply
air
flow in opposite directions through the heat accumulator ~. This means that
the
exterior air fast will meet the side of the heat accumulator ~ which has the
lowest
temperature. The exterior air will consequently be successively warmed up
along
its flow path through the heat accumulator ~, which increases ttie total
efficiency
of the heat recovery unit_
Figure ? shows a view from above of two heat recovery units according to
Figure 1,
2~ which are connected to form a heat recovery assembly. The e:cterior air
openings
20 on each unit are coupled together by a tube 31. the exhaust air openings 15
are
coupled together by a tube 31 (not shown). the used-air openings ?~ are
coupled
together by a tube 32 and the supply air openings 10 are coupled together by a
tube
3? (not shown). The tube 31. which is connected. to the exterior air openings
?0.
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wo 97J28412 ~ PCTISE97l00153
discharges into an e.~cterior air channel 33 in which a filter 7I is arranged_
The tube
31, which is connected to the exhaust air openings 1 ~ discharges in an
exhaust air
channel 33. in which a filter 72 is arranged (not shown). The tube 32 which is
connected to the used-air openings 26 discharges into a common used-air
channel
34, in which a fan 66 is arranged. The tube 32 which is connected to the
supply air
openings 10 discharges into a common supply air channel 3~. in which a fan 67
is
arranged (not shown).
The rotational movement of the heat accumulators ~ are so controlled that when
the heat accumulator ~ of one of the heat recovery units is in the first
position for
exhaust air throughflow, the heat accumulator ~ of the second heat recovery
unit is
in the second position for exterior air throuahflow, and vice versa.
In this way the ventilation in for example a building can be increased
compared with
I ~ only one heat recovery unit, whereby a nearly continuous ventilation of
the building
is achieved. Each ofthe heat recovery units can be equipped with its own
stepping
motor 62 which brings about the rotationary movement of the respective heat
accu-
mulator 5. In this case the motors 62 should be synchronized so that when one
of the
heat accumulators ~ is in the first position. the second heat accumulator ~
should be
in the second position. This synchronization can be performed with a control
means
7~. Alternately, the heat recovery assembly can be equipped with only one
motor,
whereby the rotational movement of the motor is transferred to each of the
shafts 30
on the heat accumulators a by a gear or a link mechanism (not shown).
Each of the heat recovery units can be equipped with sensors W -~7 which sense
the temperature as described above in cormection with Figure I. However, it is
also
appropriate that common sensors ~~-~7 and a single control unit 60 are
arranged for
both of the heat recovery units in order to give control signals to the
electric motors
62 or the electric motor. The control unit 60 can be connected to the control
means
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It is also possible to couple together more than nvo heat recovery units to
make a
larger heat recovery assembly.
Figure 3 shows a perspective view of a heat recovery unit according to a
second
embodiment. The casing 1 contains in this second embodiment two heat accumu-
lators ~,~', which are placed side by side in each of their own chambers
40,45. The
chambers 40,4 are separated from each other by means of a wall ~0. The casing
1
has a supply air opening 10. an exhaust air opening 1~, an exterior air
opening 20
and a used-air opening 2~, which each cooperate with the end faces 3~ of the
heat
accumulator ~ and ~'. respectively. Each of the openings 10-2~ is connected to
both chambers 40.4, which means that each opening 10-2~ extends from the first
chamber 40 to the second chamber 4~. The supply air opening 10 and the used-
air
opening 25 and respectively the exhaust air opening 1 S and the exterior air
opening 20
are separated by means of the wall part 27 respectively 28, which can be
formed as part
1 ~ of the casing 1.
A fan part 6~ which comprises two fans 66,67 (Figure 4) can be connected to
the
supply air opening 10 and the used-air opening 2~. and a filter part 70 which
comprises two filters 71.72 (Figure ~) can be connected to the exhaust air
opening
15 and the exterior air opening 20.
Precisely as in the heat recovery assembly according to Figure ?. the
rotational
movements of the heat accumulators ~,~' are so controlled that when the first
heat
accumulator ~ is in the first position for e.~chaust air throuQhflow, the
second heat
accumulator ~' is in the second position for exterior air throughflow, and
vice versa.
Consequently, the ventilation in, for e.~campIe. a building can be increased
whereby
a near enough continuous ventilation of the building is achieved. Each of the
heat
accumulators ~.~' can, as in Figure 2. be equipped with its own stepping motor
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WO 97!18412 10 PCTISE9?/OOI53
62.62'. which brins about the rotational movement of each heat accumulator
~.~'.
The motors 6'_'.6?' shall in this case be synchronized so that when the first
heat
accumulator ~ i~ in the first position, the second heat accumulator ~' shall
be in the
second position and vice versa This synchronization can take place by a
control
unit 60. Alternatively, the heat recovery unit can be equipped with only one
motor,
where the rotational movement of the motor is transmitted to each of the
shafts
of the heat accumulators by a gear or a link mechanism (not shown).
During exhaust air throuehflow when the first heat accumulator ~ is set in the
first
position. air at room temperature in the form of e.~chaust air flows in
through the
exhaust air opening 1~ and into the first chamber 40, in which the first heat
accu-
mulator ~ is positioned. The exhaust air flows subsequently through the heat
accu-
mulator 5 in a direction which substantially corresponds to the direction of
its thick-
ness. the heat accumulator ~ is thereby heated up by the throuQhflowing
exhaust
air. The air then flows out through the used-air opening ?~ in the form of
used air
och consequenti~- leaves the first chamber =10. The used air which leaves the
used-air
opening 25 can then suitably flow into a channel 82 (Figure ~), which
transports the
air out of the building.
At the same time as e.~chaust air throughflow takes place in the first chamber
40.
exterior air throu~hflow takes place in the second chamber 4~, in which the
second
heat accumulator ~' is set in the second position far exterior air
throuQhflow. Durine
exterior air throuQhflow exterior air flows in through the exterior air
opening 20 and
into the second chamber ~~. The exterior air then flows through the second
heat
2~ accumulator ~~ in a direction which essentially coincides with the
direction of its
thickness. The e~cterior air is thereby heated up by the second heat
accumulator ~'
which earlier has been warmed up by exhaust air during exhaust air
throuahflow.
The air then flows out through the supply air opening 10 in the form of supply
air
and consequently leaves the second chamber ~1~. The supply air which leaves
the
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supply air opening 10 then flows either directly into the building or into a
tube
system which distributes the air to the different rooms in the building (not
shown).
According to this embodiment according to Figure 3, a control means for
control-
Tina the heat recovery unit can be constructed so that a first sensor >j
senses the
temperature of the exterior air which is flowing into the exterior air opening
20.
This first sensor 5~ is connected to a control unit 60, and is compensated.
which
means that it gives signals to the control unit 60 which signals are the basis
for how
the heat recovery unit is to be regulated at different exterior temperatures.
A second
i0 sensor ~7 whi~h i.s placed by the supply air opening 10 and connected to
the control
unit 60 senses the temperature of the warmed up supply air which leaves the
supply
air openings 10 ~f the respective chamber ~0,4~. This second sensor ~7 is
regulated.
which means that it gives sisals to the control unit 60 which signals are a
basis for
how the heat recovery unit should be reeulated with respect to a suitably
installed
1 ~ desired value which is programmed into the control unit. Vtrhen the supply
air
temperature is below the desired value of the second sensor ~7, the control
unit 60
gives a sisal to the respective stepping motor 62,62', which are connected to
the
respective shafr 30,30' of the heat accumulators ~.~', whereby the first motor
62
rotates the first heat accumulator ~ to the second position for exterior air
throuah-
20 flow. At the same time the second stepping motor 62' rotates the second
heat
accumulator ~' to the first position for exhaust air throughflow.
As an alternative the f rst sensor 5~ senses the temperature of the used air
which
leaves the used-air openings 2~ of the respective chamber 40.4. A reference
sensor
can. for example, be placed in the building which is to be ventilated, in
order to
sense the room temperature in the building. The first sensorp3 and the
reference
sensor are connected to the control unit 60. The second sensor p7 is placed by
the
supply air openings 10 of the respective chamber X0,45 and is connected to the
control unit 60. whereby the second sensor ~7 senses the temperature of the
warmed
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up supply air. When the difference between the temperatures sensed by the
first and
second sensors 55 and respectively 57 and the temperature sensed by the
reference sensor
56 reaches a predetermined value, the control unit 60 gives a signal to the
first and
second stepping motors 62.62'. whereby the first motor 62 rotates the first
heat
accumulator ~ to the second position for exterior air throughflow. At the same
time
the second stepping motor 62' rotates the second heat accumulator ~' to the
first
position for exhaust air throughflow.
Figure ~ shows a lateral view of a heat recovew unit according to the second
I O embodiment. The first heat accumulator ~ is shown with a plurality of
parallel lines
which extend in the direction of thickness of the first heat accumulator ~.
The
parallel lines symbolize that the first heat accumulator ~ is built up by a
plurality
of plates 37. The solid arrows show exhaust air flows through the heat
recovery
assembly. The first heat accumulator 6 is set in the first position for the
exhaust air
16 throuQhflow, wherein exhaust air flows through the exhaust air opening I S
into the
first chamber X10, through the first heat accumulator ~ and out through the
used-air
opening ?5 in the form of used air.
The second heat accumulator ~' is hidden behind the wall SO which separates
the
20 first and second chambers X0,45. thus the contours of the second heat
accumulator
are only shown with dashed lines. The second heat accumulator 5' is set in the
second position for exterior air throughflow which is shown with dashed
arrows.
A fan part 66 which comprises two fans 66_67 is connected to the supply air
opening
25 10 and the used-air opening 35, and a filter part 70 which comprises two
filters 71.
72 is connected to the exhaust air opening 1 ~ and the exterior air opening
20.
Figure ~ shows an example of the application of a heat recovery unit according
to
the second embodiment. The heat recovery unit can_ for example. be placed in
an
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isolated place in a building 79. However. it is also possible to place the
heat reco-
ven~ unit outside the building 79. Exhaust air F in the form of the interior
air of the
building 79 is led through an exhaust air channel 80 into the filter part 70
of the heat
recoven~ unit and further in through the e,Yhaust air opening 15 to one of the
two
s chambers 40 alt. 4~; which each contain a heat accumulator ~,~'. The exhaust
air
passes through one of the heat accumulators 5,5' and out through the used-air
opening 2~ in the form of used air A which is led through a used-air channel
82 in
order to be let out outside the building 79. At the same time. exterior air U
is led
through an exterior air channel 84 into the filter part 70 of the heat
recovery unit and
further in through the exterior air opening ?0 to the second one of the two
chambers
40 alt. 4~. The e:cterior air passes through the second of the two heat
accumulators ~
,5' and out through the supply air opening 10 in the form of supply air T,
which
is led through a supply air channel 86 in order to be let into the building
79.
1~ Figure 6 shows a heat recovery unit according to Figure 4 where both the
first and
the second heat accumulators ~,~' are in a third position, in which position
neither
of the openings 10-2S in the casino 1 of the heat recovery unit are closed by
means
of the end faces 3 ~ of the heat accumulators ~.~'. On the other hand both the
exterior openings 20 and the used-air openings 2~ are closed by means of valve
leaves 90 which prevent exterior air to flaw from the exterior air opening 20
and
the exhaust air opening 25 to the supply air opening 10. In the third
position,
exhaust air can flow from the exhaust air opening 1S to the supply air opening
10
without passing through the heat accumulators S,S', whereby an internal air
circu-
lotion in, for example, a building can be achieved. The third position can be
taken
?S during, for example. a power cut or during night or weekend stoppages. when
the
stepping motors which bring about the rotational movement of the heat accumula-
tors ~.~' can be so designed that they automatically rotate the heat
accumulators S.S'
to the third position during shutdowns.
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WO 97128412 14 PCT/SE97/00153
Fieure 7 shows a lateral view of a heat recovery unit according to a third
embodi-
ment. The first heat accumulator ~ here is tipped into the second position for
exterior air throughflow. At the same time the second heat accumulator ~' is
tipped
into the first position for exhaust air throughflow. Each of the heat
accumulators
~.~' is partitioned with a dividing wall 9~. which e;ctends in the direction
of thick-
ness of the heat accumulators ~,~', whereby this dividing wall 9~ cooperates
with
valve leaves 96, which are synchronized with the rotational movement of the
asso-
ciated heat accumulator ~.~'. This synchronization can. for example. be
achieved
by means of a link system (not shown). The dividing wall 95 and the valve
iPaves
96 can together cooperate in order to minimize the losses in the heat recovery
when
the heat accumulators ~,~' rotatate from the first to the second position. and
vice
versa. Another object of the dividing wall 95 and the valve leaves 96 will be
explained in connection with Figure 8.
1 ~ Figure 8 shows a heat recovery unit according to Figure 7, where both the
first and
the second heat accumulators ~.~' are in a third position, in which position
none of
the openings I 0-25 in the casing I of the heat recovery unit are closed by
means of
the end faces 3~ of the heat accumulators ~.~'. By means of the dividing wall
95 and
the valve leaves 96, however, two, from each other separated. substantially
airtight
?0 spaces are formed on each side of the dividing wall 95 and the valve leaves
96.
Consequently. e.chaust air can flow through the e;chaust air opening 1 ~ and
out
throu~ll the supply air opening 10, whereby a recycle air function in the form
of
an intemaI air circulation is achieved in, for example, a building. As
described in
connection with Figure 6, the third position can be taken during, for example,
25 power failures.
In the summer months when the e;cterior air temperature is relatively high.
the
accumulators ~,~' in the heat recovery unit can remain in either the first or
the
second position for a long time. A time function built into the control unit
60 can
CA 02244064 2004-O1-29
WO 97/28412 I 7 PCTISE9'7100153
then ''exercise' the rotational function at regular time intervals. for
example one
rotation or tipping per day. whereby the movable parts of the heat recovery
unit
are brought into motion in order to prevent them from sticking. -
An advantage of the heat recovery unit according to the invention is that it
can be
applied at a long distance from an outer wall in a building, as the air the
whole time
flows in the same direction in the channels 80-86 which are connected to the
heat
recovery unit.
14 Another advantage of the heat recovery unit is that if the rotating shafr
30 of the heat
accumulator ~.~' is placed horizontally, exhaust air will flow substantially
upwards
through the heat accumulator ~_~'. This means that water which condenses on
the
heat absorbing surfaces of the heat accumulator 5,~' will stay there and in
the
second position of the accumulator will be absorbed by the exterior air which
flows
1 ~ through the heat accumulator 5.~'. Consequently, no thaw water piping for
the heat
recovery unit is required. The efficiency of the heat recovery unit is also
increased
in this way because latent heat. which from the beginning is contained in the
water
vapour, is recovered.
20 Yet another advantage of the heat recovery unit according to the invention
is that
the heat accumulator ~,~' is easy to clean because the throuahflow direction
of the
air through the heat accumulator 5,5' occurs substantially in the direction of
its thickness
which is considerably less than its length and width, so that the throughflow
channels are
short and easy to clean by e.g. by rinsing with water.
7J
Yet another advantage of the heat recovery unit according to the present
invention
is that the sound change during the change from the exterior air throuahflow
to the
exhaust air throuehflow and vice versa is very low. According to the
invention,
air flows the whole time in the same direction through the openings 10-?~ in
the
CA 02244064 2005-02-28
16
casino I and in the channels 80-86 which are connected thereto. which means
that
the sound chance is low because no large air volume has to chance direction of
flow.
Yet another advantage of the heat recovery unit according to the present
invention is
that the pressure drop over the heat accumulator ~.~' is low because the path
of the
air through the heat accumulator ~,~' is relatively short. 'This means that a
Lower fan
capacity is required in order to produce the flow of the air and it also means
a lower
sound level.
It has been described above how heat can be recovered by the heat recovery
unit
according to the invention. It is: however, possible by means of the heat
recovery
unit to shut out warm air from, for example, a building in which the indoor
tempera-
ture should be less than the outdoor temperature. The heat recovery unit will
then
1 ~ work the other way round, whereby warm exterior air will give off its heat
to the
heat accumulator 5,5' which has been cooled by the .exhaust air throughflow.
The exterior air will thus be cooled down and flow into the rooms of the
building
in the. form of cool supply air.
The foregoing description of the preferred embodiments of the present
invention has been
presented for the purposes of illustration and description. It is not intended
to be exhaustive
or to limit the application. Many modifications, variations and adaptations
are possible
without departing from the scope of the invention.
