U.S. patent application number 15/301566 was filed with the patent office on 2017-04-27 for recuperator, the heat-exchanging channels of which extend transversely of the main flow direction.
The applicant listed for this patent is Level Holding B.V.. Invention is credited to Peter HOOGENDOORN, Wessel Bart VELTKAMP.
Application Number | 20170115026 15/301566 |
Document ID | / |
Family ID | 50896407 |
Filed Date | 2017-04-27 |
United States Patent
Application |
20170115026 |
Kind Code |
A1 |
VELTKAMP; Wessel Bart ; et
al. |
April 27, 2017 |
Recuperator, the Heat-Exchanging Channels of which Extend
Transversely of the Main Flow Direction
Abstract
The invention relates to a recuperator (7), comprising at least
a recuperator unit with heat-exchanging channels (5, 6) extending
parallel to each other, a first header (63) placed on a first side
of the recuperator unit and having a triangular cross-section, one
surface of which connects to a first end of the heat-exchanging
channels (5, 6) of the recuperator unit, a second header (64)
placed on the second side of the recuperator unit and having a
triangular cross-section, one surface of which connects to the
second side of the heat-exchanging channels (5, 6) of the
recuperator unit, supply ducts (1, 4) extending to a second surface
of the first and the second header (63, 64) and discharge ducts (2,
3) extending from the third surface of the first and the second
header (63, 64), wherein the supply ducts (1, 4) and the discharge
ducts (2, 3) extend transversely of the longitudinal direction of
the heat-exchanging channels (5, 6), wherein the supply ducts (1,
4) and the discharge ducts (3, 4) extend on the sides of the
headers (63, 64) lying opposite the recuperator units.
Inventors: |
VELTKAMP; Wessel Bart; (Son,
NL) ; HOOGENDOORN; Peter; (Son, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Level Holding B.V. |
Son |
|
NL |
|
|
Family ID: |
50896407 |
Appl. No.: |
15/301566 |
Filed: |
April 2, 2015 |
PCT Filed: |
April 2, 2015 |
PCT NO: |
PCT/NL2015/050217 |
371 Date: |
October 3, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 9/02 20130101; F28D
9/0075 20130101; F28D 9/0018 20130101; F28F 2245/02 20130101; F24F
2007/003 20130101; F28D 9/00 20130101; F28F 21/065 20130101; F28F
9/0263 20130101; Y02B 30/56 20130101; F28D 21/0014 20130101; F24F
12/006 20130101; F28F 21/02 20130101; Y02B 30/563 20130101; F28F
27/02 20130101; F28F 2009/029 20130101; F28F 9/0214 20130101; F28D
9/0043 20130101 |
International
Class: |
F24F 12/00 20060101
F24F012/00; F28F 21/02 20060101 F28F021/02; F28F 27/02 20060101
F28F027/02; F28D 9/00 20060101 F28D009/00; F28F 9/02 20060101
F28F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 2, 2014 |
NL |
2012548 |
Claims
1. A recuperator, comprising: at least a first recuperator unit
with heat-exchanging channels extending parallel to each other; a
first header placed on a first side of the recuperator unit and
having a triangular cross-section, one surface of which connects to
a first end of the heat-exchanging channels of the recuperator
unit; a second header placed on the second side of the recuperator
unit and having a triangular cross-section, one surface of which
connects to the second side of the heat-exchanging channels of the
recuperator unit; supply ducts extending to a second surface of the
first and the second header; and discharge ducts extending from the
third surface of the first and the second header, wherein the
supply ducts and the discharge ducts extend transversely of the
longitudinal direction of the heat-exchanging channels, wherein the
supply ducts and the discharge ducts extend on the sides of the
headers lying opposite the recuperator units, the passage of the
supply ducts decreases in the flow direction, and the passage of
the discharge ducts increases in the flow direction.
2. The recuperator as claimed in claim 1, wherein the supply ducts
and the discharge ducts extend substantially parallel to the
intersecting line between the first and the second surface of the
headers.
3. The recuperator as claimed in claim 1, wherein the supply ducts
and the discharge ducts extend substantially transversely of the
intersecting line between the second and the third surface of the
headers.
4. The recuperator as claimed in claim 3, wherein in that the
recuperator is provided with at least a second recuperator
unit.
5. The recuperator as claimed in any of claim 1, wherein the
recuperator is placed in a rectangular housing.
6. The recuperator as claimed in claim 1, wherein the recuperator
unit has a round form and extends between two concentric cylinders,
the channels extend radially relative to the cylinders, the first
header is situated on the inner side of the recuperator unit, the
second header is situated on the outer side of the recuperator
unit, the supply and discharge ducts extend in the axial direction
of the cylinders, one supply duct and one discharge duct extend on
the inner side of the recuperator unit, and one supply duct and one
discharge duct extend on the outer side of the recuperator
unit.
7. The recuperator as claimed in claim 6, wherein a substantially
tubular distributor is arranged between the central supply duct and
discharge duct on the one hand and the heat-exchanging channels on
the other, which distributor is divided into sections by means of
internal extensions of walls extending between the heat-exchanging
channels, and that each of the sections is connected to the
discharge duct or to the supply duct, and that a substantially
tubular distributor is arranged between the supply duct and
discharge duct arranged on the periphery on the one hand and the
heat-exchanging channels on the other, which distributor is divided
into sections by means of extensions of walls extending between the
heat-exchanging channels, and that each of the sections is
connected to the discharge duct or supply duct arranged on the
periphery.
8. The recuperator as claimed in claim 1, wherein the recuperator
unit is provided with plates which extend parallel to each other
and which separate channels of different sort and extend
transversely of the intersecting line between the second and the
third surface of the headers.
9. The recuperator as claimed in claim 8, wherein at least some of
the number of plates are provided with a profile which defines
channels.
10. The recuperator as claimed in claim 1, wherein the recuperator
is placed in a housing with the form of a straight circular
cylinder.
11. The recuperator as claimed in claim 10, wherein the central
axis of the recuperator unit extends at an angle to the axis of the
cylindrical housing.
12. The recuperator as claimed in claim 11, wherein a controllable
alternating valve is arranged against both end walls of the housing
on either side of the recuperator unit and connected for
repetitively and simultaneously alternating the inlet channel and
the outlet channel, and that the recuperator is a recuperator
configured to recover latent heat.
13. The recuperator as claimed in claim 12, wherein the alternating
valves are both provided with a fixedly arranged valve seat
provided with openings, which openings are connected to a supply
duct or discharge duct, and with a rotatable valve disc connecting
to the valve seat and provided with openings.
14. The recuperator as claimed in claim 13, wherein at least one
bypass channel is arranged in the housing and that the bypass
channel is connected to openings arranged in both valve seats.
15. The recuperator as claimed in claim 13, wherein the valve seats
are provided with closed parts and that the valve discs are movable
into a position in which the openings in the valve discs are closed
by closed parts of the valve seat.
16. The recuperator as claimed in claim 13, wherein the valve discs
are movable in axial direction and that the recuperator is provided
with a control member configured to move the valve in axial
direction away from the valve seat prior to a change in the
position of the valve and to move the valve toward the valve seat
after a change in the position of the valve.
17. The recuperator as claimed in claim 13, wherein the rotatable
valves are provided with an outward extending, substantially
cylinder jacket-like wall part which connects to the valve disc and
is co-rotatable with the valve disc, that the valve seats are each
connected to a substantially cylinder jacket-like fixed wall part
which is in contact with the associated rotatable wall part, that
in both wall parts openings are arranged which, depending on the
position of the valve disc, can be brought into overlap and that
the openings arranged in the fixed wall part are connectable to the
surrounding area or to the indoor space.
18. The recuperator as claimed in claim 17, wherein the
substantially cylinder jacket-like parts of the rotatable valves
and the parts of the housing connecting thereto take a slightly
conical form.
19. The recuperator as claimed in claim 8, wherein the plates are
provided with guide means for guiding the change in direction of
the airflows entering and exiting the channels.
20. The recuperator as claimed in claim 8, wherein the plates are
provided on at least one side with a layer of SiO.sub.2.
Description
[0001] The invention relates to a recuperator, comprising at least
a first recuperator unit with heat-exchanging channels extending
parallel to each other, a first header placed on a first side of
the recuperator unit and having the form of a three-sided prism, a
first surface of which connects to a first end of the
heat-exchanging channels of the recuperator unit, a second header
placed on the second side of the recuperator unit and having the
form of a three-sided prism, a first surface of which connects to
the second side of the heat-exchanging channels of the recuperator
unit, supply ducts extending to a second surface of the first and
the second header and discharge ducts extending from the third
surface of the first and the second header, wherein the supply
ducts and the discharge ducts extend transversely of the
longitudinal direction of the heat-exchanging channels.
[0002] Such recuperators are generally known, inter alia from
NL-C-1 000 706. In these recuperators the heat-exchanging channels
extend substantially parallel to the main flow direction in the
recuperator. Recuperators with a greater length than width in the
main flow direction have a relatively great pressure drop, this
requiring additional fan capacity. This reduces the net
effectiveness of the recuperator.
[0003] In the housing and utility markets there is a need for a
recuperator per room, preferably incorporated in the shell of the
building. A recuperator can be placed for this purpose in a hole
drilled in a wall or can be incorporated in a window frame. These
applications result in a length-width ratio of 2 or more, while in
the currently usual recuperators the ratio is .about.0.5. In order
to achieve the effectiveness of 92% or more required for comfort in
the case of these recuperators the pressure drop becomes too high
at the required air flow rate, so that more powerful fans are used
and the effectiveness decreases.
[0004] The object of the invention is to provide such a
recuperator, wherein these drawbacks are obviated or reduced.
[0005] The invention provides for this purpose a recuperator of the
above stated type, wherein the supply ducts and the discharge ducts
extend at the sides of the headers lying opposite the recuperator
units, the passage of the supply ducts decreases in the flow
direction and wherein the passage of the discharge ducts increases
in the flow direction.
[0006] In this configuration the supply and discharge ducts extend
on either side of the combination of the recuperator units and the
headers and transversely of the longitudinal direction of the
heat-exchanging channels. Placing the heat-exchanging channels
perpendicularly of the main flow direction reverses the ratio of
length and width of the assembly of recuperator unit, headers and
supply and discharge ducts so that the pressure drop is reduced,
while the requirements in respect of comfort can still be met since
after all more and shorter channels are connected in parallel. The
supply to and discharge from the heat-exchanging channels does then
have to take place such that the flow rate is distributed evenly
over the heat-exchanging channels, this being achieved by said form
of the supply and discharge ducts.
[0007] According to the invention the supply and discharge ducts
extend in a plane extending transversely of the heat-exchanging
channels. A first embodiment provides the measure that the supply
and discharge ducts extend substantially parallel to the
intersecting line between the second and the third surface of the
headers. The recuperator units are usually assembled from stacked
plates extending into the prismatic headers. These plates then
extend transversely of the intersecting line between the first and
the second surface of the prismatic headers. According to this
embodiment the supply and discharge ducts then extend transversely
of the plates. The capacity of the recuperator unit can then be
increased by stacking more plates on each other. Since the supply
and discharge ducts then extend parallel to the stacking direction,
they can be easily brought into contact with all parts of the
headers. Other production techniques are not otherwise precluded;
it is thus possible to make use of recuperator units manufactured
in other manner, for instance by extrusion or by injection
moulding.
[0008] According to an alternative embodiment, the supply ducts and
the discharge ducts extend substantially transversely of the
intersecting line between the second and the third surface of the
prismatic headers. This is the other technically applicable option
for the direction of the supply and discharge ducts, although the
principle option of oblique channels is not precluded.
[0009] In the case of recuperator units of the above stated type
with a large width in the direction of the intersecting line
between the second and the third surface of the headers, this would
result in excessively wide supply and discharge ducts which are
difficult to place in a housing. The width of these supply and
discharge ducts becomes smaller when the recuperator is provided
with at least a second recuperator unit which is connected to the
same supply and discharge ducts. When use is made in this
embodiment of a recuperator unit assembled from flat plates, the
supply and discharge ducts then extend parallel to the plates as a
result of the fact that the plates extend into the headers. In view
of the usually limited width of the plates and the great length of
the assembly of recuperator units, headers and supply and discharge
ducts, different recuperator units will have to be connected
successively and in parallel.
[0010] Preferably the recuperator is placed in a rectangular
housing.
[0011] According to an alternative configuration, the recuperator
unit has a round cross-section and extends between two concentric
cylinders, wherein the channels extend radially relative to the
cylinders, the first header is situated on the inner side of the
recuperator unit, the second header is situated on the outer side
of the recuperator unit, the supply and discharge ducts extend in
the axial direction of the cylinders, one supply duct and one
discharge duct extend on the inner side of the recuperator unit,
and wherein one supply duct and one discharge duct extend on the
outer side of the recuperator unit. This embodiment is
particularly, though not exclusively, suitable for placing in round
holes in walls.
[0012] An efficient configuration results when a substantially
tubular distributor is arranged between the central supply duct and
discharge duct on one hand and the heat-exchanging channels on the
other, which distributor is divided into sections by means of
internal extensions of walls extending between the heat-exchanging
channels, and each of the sections is connected to the discharge
duct or to the supply duct, and a substantially tubular distributor
is arranged between the supply duct and discharge duct arranged on
the periphery on the one hand and the heat-exchanging channels on
the other, which distributor is divided into sections by means of
extensions of walls extending between the heat-exchanging channels,
and each of the sections is connected to the discharge duct or
supply duct arranged on the periphery.
[0013] According to an attractive embodiment, the recuperator unit
is provided with plates which extend parallel to each other and
which separate channels of different sort and extend transversely
of the intersecting line between the second and the third surface
of the headers.
[0014] At least some of the number of plates are preferably
provided with a profile which defines channels.
[0015] According to another preferred embodiment, the housing takes
the form of a straight circular cylinder. This form of the housing
can advantageously be combined with an array of heat-exchanging
channels with a rectangular form and together with the headers
space is then created there for the supply and discharge ducts and
possibly for one or more bypass channels.
[0016] When the central axis of the recuperator unit extends at an
angle to the central axis of the cylindrical housing, it is easy to
obtain a configuration wherein the passage of the supply ducts
decreases in the flow direction and the passage of the discharge
ducts increases in the flow direction.
[0017] Recuperators form condensation when the temperature of the
one medium is lower than the saturation temperature of the other
medium. If the temperature of the primary medium lies below
freezing point, ice can then also be formed. In the case of a
decentralized recuperator per room in the housing or utility market
it is technically difficult to discharge condensation and to
prevent formation of ice. In order to remain within the comfort
range in the room moisture has to be recovered at low outdoor
temperature, and in the case of high outdoor temperature and
humidity the moisture from outside has to be relinquished to the
outgoing indoor air flow. The above requirements can be met by
cyclical alternation of the flow in the counterflow channels of the
two media. The condensation and ice formed in the one (secondary)
medium is then evaporated and sublimated in the other (primary)
medium. A further embodiment provides for this purpose the measure
that a controllable alternating valve is arranged in the housing on
either side of the recuperator unit and connected for repetitively
and simultaneously alternating the inlet channel and the outlet
channel. The recuperator hereby becomes suitable for recovering
latent heat.
[0018] The valves can be embodied in diverse ways. It is thus
possible to make use of slide valves, although it is recommended
that the alternating valves are each provided with a fixedly
arranged valve seat provided with openings, which openings are
connected to the supply and discharge ducts, and with a rotatable
disc connecting to the valve seat. The valves can thus be rotated
individually though simultaneously. It is likewise possible to
rotate the assembly of heat-exchanging channels with the associated
supply and discharge ducts in its entirety. The advantage relative
to the enthalpy recuperator per se forming part of the prior art is
that fewer valves are necessary, that the seal is simpler, the flow
resistance lower and the switching time shorter. If the moisture
production in the indoor space is greater than the amount of
moisture which cannot be recovered, the valves can be connected
asynchronously, whereby condensation moisture in the recuperator
can be discharged.
[0019] It must be possible to switch off recuperation when the heat
production indoors is sufficient or is more than necessary to keep
the space at temperature, and the outdoor temperature is lower than
the indoor temperature. It is also attractive to cool the space
with outside air at night when a cooling demand is anticipated
during the day. These requirements can be met with the same
rotating valves (or rotating recuperator) as those for the enthalpy
recuperation. It is recommended for this purpose that at least one
bypass channel is arranged in the housing and the bypass channel is
connected to openings arranged in the valve seats.
[0020] It may be desirable to close the recuperator, for instance
in the case of calamities. A relevant embodiment provides for this
purpose the measure that the valve seat is provided with closed
parts and the valve discs are movable into a position in which the
openings arranged in the valve discs are closed by closed parts of
the valve seat.
[0021] In order to keep the seals as leakage-free as possible, it
is preferred that the valve discs are movable in axial direction
and that the recuperator is provided with a control member
configured to move the valve in axial direction away from the valve
seat prior to a change in the position of the valve and to move the
valve toward the valve seat after a change in the position of the
valve. The seals are now after all only in abutting contact and not
in sliding contact.
[0022] In order to provide more options it is recommended that the
rotatable valves are provided with an outward extending,
substantially cylinder jacket-like wall part which connects to the
valve disc and is co-rotatable with the valve disc, that the valve
seats are each connected to a substantially cylinder jacket-like
fixed wall part which is in contact with the associated rotatable
wall part, that in both wall parts openings are arranged which,
depending on the position of the valve disc, can be brought into
overlap and that the openings arranged in the fixed wall part are
connectable to the surrounding area or to the indoor space.
[0023] In order to facilitate the axial movement of the valves,
particularly as a result of the seals, it is recommended that the
substantially cylindrical part of the rotatable valves and the
parts of the housing connecting thereto take a slightly conical
form.
[0024] The housing is preferably configured to form part of a
window frame. A considerable space-saving can hereby be achieved,
while the option is provided of placing the recuperator together
with the window frame.
[0025] In order to reduce flow losses during the change in
direction caused by the invention it is attractive for the plates
to be provided with guide means for guiding the change in direction
of the airflows entering and exiting the channels.
[0026] The plates are preferably provided on at least one side with
a hydrophilic layer, such as a layer of SiO.sub.2. The capillary
action of the surface tension is hereby increased and the
moistening improved.
[0027] In homes any breaches in the shell must have sufficient
sound damping, so that the required sound level is achieved in the
home. The fan for the exhaust air is preferably placed indoors in
order to prevent formation of ice in the fan at very low outdoor
temperatures. The fan noise must be low and, if necessary, damped.
The connection between recuperator and wall has to be airtight and
sound-damping. The sound damping is usually achieved by damping the
recuperator itself, wherein the counterflow channels lie
transversely of the axis of the breach in the shell and outside
noise can only reach the indoor space via a labyrinth. Where this
damping is not sufficient, sound-damping material can be applied in
the inner and outer gratings, preferably in the form of a flexible
seal. The dynamic pressure on the inflow side during inflow into
the heat-exchanging channels has a sign opposite to that on the
outflow side, so that the static pressure drop over the outflow
channel is greater than that over the inflow channel. This
difference causes a non-uniform flow through the channels over the
longitudinal axis of the recuperator. This difference is reduced by
making the cross-sectional variation of inflow and outflow channels
asymmetrical.
[0028] The invention will be elucidated hereinbelow with reference
to the accompanying figures, in which:
[0029] FIG. 1 is a schematic perspective view of plates and
heat-exchanging channels formed by the plates in a prior art
configuration;
[0030] FIG. 2 is a schematic perspective view of plates and
heat-exchanging channels formed by the plates in a first
configuration according to the invention;
[0031] FIG. 3 is a schematic perspective view of plates and
heat-exchanging channels formed by the plates in a second
configuration according to the invention;
[0032] FIG. 4 is a schematic perspective view of a recuperator with
channels according to a third configuration according to the
invention;
[0033] FIG. 5 is a schematic perspective view of a recuperator with
channels according to a fourth configuration according to the
invention;
[0034] FIG. 6 is a schematic perspective view of the positioning of
a recuperator in a round housing;
[0035] FIG. 7 is a schematic perspective view of the positioning of
a recuperator in a configuration with insulation of cold
channels;
[0036] FIG. 8 is a schematic perspective view of a recuperator with
rotating valves which is placed obliquely in a round hole in a
wall, with flows entering and exiting axially;
[0037] FIG. 9 is a schematic representation of the position of the
valves in a first option of the recuperator shown in FIG. 8;
[0038] FIG. 10 is a schematic perspective view of a recuperator
with rotating valves which is placed obliquely in a round hole in a
wall, with flows entering and exiting axially;
[0039] FIG. 11 is a schematic representation of the position of the
valves in a second option of the axial-axial inflow and
outflow;
[0040] FIG. 12 is a schematic perspective view of a seal of the
valve on the tube and recuperator with mechanism for preventing
friction during rotation;
[0041] FIG. 13 shows a configuration with a single valve;
[0042] FIG. 14 shows a configuration with axial and radial inflow
and outflow option 1;
[0043] FIG. 15 is a schematic representation of the position of the
valves in option 1 of the axial-radial inflow and outflow;
[0044] FIG. 16 is a schematic representation of the position of the
valves in option 2 of the axial-radial inflow and outflow;
[0045] FIG. 17 is a schematic representation of the position of the
valves in option 3 of the axial-radial inflow and outflow;
[0046] FIG. 18 is a schematic representation of the position of the
valves in option 4 of the axial-radial inflow and outflow;
[0047] FIG. 19 shows sealing of the axial-radial valves;
[0048] FIG. 20 shows an enthalpy recuperator in a window frame;
and
[0049] FIG. 21 shows a cross-section of recuperator and housing
with therein the thickened portion of the tube and the vanes at the
inflow and outflow of the heat-exchanging channels.
[0050] FIG. 1 shows schematically a limited number of plates 9 of a
prior art recuperator 7 which is dimensioned for placing in a
passage with a diameter of 150 mm in a wall with a thickness of 300
mm. For the sake of simplicity the housing of the recuperator is
not shown. Plates 9 close heat-exchanging channels of respective
first and second sorts 5 and 6. The heat-exchanging channels of the
two sorts 5, 6 are separated by plates 9. Plates 9 can all be
corrugated, although it is also possible for plates 9 to be
alternately corrugated and flat. Plates 9 continue outside the
actual heat-exchanging channels 5, 6 into so-called header plates
10, 11. The mutually stacked header plates 10, 11 form headers 63,
64 on either side of the recuperator unit. In the present
application headers 63, 64 have a triangular form and the
heat-exchanging channels 5 of the first sort debouch in a first
surface of headers 63, 64 and the heat-exchanging channels of the
second sort 6 debouch in a second surface of headers 63, 64. Header
63 has on the right an opening which connects to a channel 1 and
through which indoor air flows into the recuperator to channels 5
of the first sort, and on the left an opening which connects to
channel 2 and through which air flows in from channels 6 of the
second sort. Header 64 has on the left an opening which connects to
a channel 3 and through which air from channels 5 of the first sort
exits the recuperator to the outside and on the right an opening
which connects to a channel 4 and through which outside air flows
to channels 6 of the second sort.
[0051] Because channels 5 of the first sort and those 6 of the
second sort are intimately coupled thermally to each other, heat
transfer takes place between the gas flows flowing through channels
5, 6 while a separation between the gas flows is maintained. It
will be apparent from the shown configuration that channels 5, 6
extend in the longitudinal direction of recuperator 7 and are thus
relatively long; they are considerably longer than the width or the
height of recuperator 7, whereby the flow resistance is relatively
great. Such recuperators are known from the prior art.
[0052] FIG. 2 shows in the same way as FIG. 1 the configuration of
a recuperator 7 according to the invention. This recuperator is
also constructed from plates 9 which define heat-exchanging
channels 5, 6. The detail view here shows the configuration of
plates 9 and the heat-exchanging channels 5, 6. Plates 9 extend
here perpendicularly of the longitudinal direction of the housing
of the recuperator and thereby substantially of the main flow
direction. Plates 9, and thereby channels 5, 6, are therefore
considerably shorter than those in the prior art recuperator shown
in FIG. 1, and the number of channels 5, 6 is therefore
considerably greater. The recuperator according to the invention
also has triangular prismatic headers 63, 64. This configuration
requires that supply and discharge ducts connecting to headers 63,
64 extend over the length of the recuperator.
[0053] FIG. 2 also shows a supply duct 1 extending from indoors to
the recuperator and connecting to the left-hand surface of upper
header 63, a discharge duct 3 extending outside from the
recuperator and connecting to the right-hand surface of lower
header 64, a supply duct 4 extending from the outside to the
recuperator and connecting to the left-hand surface of lower header
64 and a discharge duct 2 extending indoors from the recuperator
and connecting to the right-hand surface of upper header 63. Supply
ducts 1, 4 have a cross-sectional area decreasing in the flow
direction and discharge ducts 2, 3 have a cross-sectional area
increasing in the flow direction so that the flow speed of the
medium in the supply and discharge ducts is as far as possible
always the same. Supply duct 1 and the adjoining discharge duct 2
are separated by a baffle 12, and supply duct 4 and discharge duct
3 are separated by a baffle 13.
[0054] FIG. 3 shows schematically a second embodiment of the
invention. Plates 9 extend parallel here to the main flow
direction, or the longitudinal direction, of recuperator 7 while
the heat-exchanging channels 5, 6 extend transversely of the
longitudinal direction thereof as in the first embodiment. Since
plates 9 generally have a width smaller than the length of
recuperator 7, a number of plates 9 is placed mutually in line. In
other words, a number of recuperator elements are placed
successively in the recuperator. Four of these recuperator elements
are present in the shown embodiment. Each of these has on its upper
and underside a respective prismatic header 63, 64. At variance
with the first embodiment however, the axis of symmetry of these
headers 63, 64 extends transversely of the longitudinal axis of the
recuperator. The connection of the supply and discharge ducts is
therefore more complicated than in the first embodiment. As in the
first embodiment, two supply ducts 1, 4 and two discharge ducts 2,
3 are present which are likewise separated by a respective baffle
12, 13, although the different headers are also mutually separated
by transverse baffles 14 which connect to baffles 12, 13 and which
extend transversely of the longitudinal direction of recuperator 7.
Separating baffles 15 extending transversely of the direction of
heat-exchanging channels 5, 6, in each case over half the width of
a header 10, 11, separate the ingoing and outgoing airflows. These
separating baffles 15 are placed in a checkerboard pattern. In this
second embodiment of the invention the average cross-sectional area
of the supply ducts also decreases in the flow direction and the
average cross-sectional area of the discharge ducts increases in
the flow direction, albeit in less regular manner than in the first
embodiment.
[0055] FIG. 4 shows a third configuration wherein heat-exchanging
channels 5, 6 extend in radial direction perpendicularly of the
main flow direction and are placed together in the form of a ring.
Heat-exchanging channels 5, 6 have a width increasing with the
radius, whereby the flow remains in the entry zone over the whole
channel length. This increases the heat transfer, but also the
pressure drop.
[0056] In the interior of the array of heat-exchanging channels 5,
6 arranged in the form of a ring a supply duct 4 and a discharge
duct 3 are formed by placing a baffle 13 extending between the two
channels. A tubular distributor which fulfils the function of
header is placed between channels 3, 4 on the one hand and the
heat-exchanging channels on the other. Plates 9, between which the
heat-exchanging channels 5, 6 are formed, extend here in radial
direction in this tubular distributor as far as supply duct 4 and
discharge duct 3, and here form plate parts 11. The spaces between
these plate parts 11 are alternately connected to discharge duct 3
or to supply duct 4. The common outer wall 65 of supply duct 4 and
discharge duct 3 is therefore interrupted alternately on the
underside and on the upper side so that supply duct 4 is connected
in each case to every second space between plate parts 11, and
discharge duct 3 is connected in each case to the remaining spaces
between plate parts 11.
[0057] Placed on the outer side of the heat-exchanging channels 5,6
arranged in the form of a ring is an elliptically shaped baffle 12,
so that a supply duct 1 and a discharge duct 2 are also created
here. The air from the room flows via channel 1 to the space
between plates 16 and 17 through heat-exchanging channel 6 and then
to the outside via channel 3. The air from outside flows via
channel 4 to heat-exchanging channel 5 and via channel 2 to the
room. Walls 16, 17 are preferably of the same form, wherein each
successive surface is rotated axially through 180.degree. relative
to the adjacent wall. Injection moulding of these components and
connection of the sealing surfaces by means of for instance
ultrasonic welding are then possible.
[0058] According to a variant of this embodiment, the
heat-exchanging channels 5, 6 extend axially. This configuration is
shown in FIG. 5, wherein only a segment of two heat-exchanging
channels 5, 6 is shown for the sake of clarity. Since the plates of
finite thickness cannot run as far as the centre, the central space
is used as bypass channel 18, the function of which will be
elucidated below. The air coming from the indoor space flows via
annular channel 1 to the space between header plates 10 and then
via heat-exchanging channels 5 to the space between header plates
11 and via annular channel 3 to the outside. The air coming from
outside flows via annular channel 4 to the space between header
plates 11, via heat-exchanging channels 6 to the space between
header plates 10 and via annular channel 2 to the room. The inner
and outer diameters of channels 1, 2, 3, 4 have to be chosen such
that the pressure drop in headers 10, 11 is mainly equal. Less
pressure drop and more heat-exchanging surface area can be obtained
by making header surfaces 10, 11 triangular, wherein the header
tapers from the inflow and outflow to a height of zero on the other
side.
[0059] As already elucidated above, the recuperator according to
the invention is particularly suitable for application in a single
space. It is then recommended that the recuperator is placed in the
wall. A round hole has to be drilled for this purpose in an outer
wall. Usually a hole is drilled with a diameter of 150 mm and the
wall has a thickness of 300 mm. The hexagonal prismatic housing of
recuperator 7 is then placed in the hole, wherein the array of
heat-exchanging channels preferably extends obliquely in the
longitudinal direction of the circular cylindrical housing, whereby
space is automatically created for supply and discharge ducts.
Space for channels, such as bypass channels, is also created at the
sides of the recuperator inside the housing. Control equipment can
also be accommodated in this space.
[0060] FIG. 6 shows such an embodiment in a circular cylindrical
housing 19. The array 20 of heat-exchanging channels 5, 6 with the
configuration of a hexagonal prism according to the first
embodiment is placed in housing 19 in an inclining position. The
two triangular prismatic headers 10, 11 are here placed connecting
to the substantially rectangular array 20 of heat-exchanging
channels 5, 6, and supply and discharge ducts 1-4 are arranged.
These supply and discharge ducts 1-4 are all bounded by the
respective surface of header 10, 11, housing 19 and baffles 12, 13.
Also present are four baffles 21 which extend in substantially
radial direction between headers 10, 11 and housing 19 and which
further bound the supply and discharge ducts 1-4. Formed between
the pairs of baffles 21 are secondary channels 18 which are not
essential for the primary function of the recuperator, so that they
can be used as bypass channel or as space for placing
equipment.
[0061] A drawback of the thus formed channels when placed in a hole
arranged in an outer wall is that the cold air coming from outside
is carried as far as the inner cavity wall 23, whereby the inner
cavity wall 23 can cool and fall below the condensation point,
which results in heat loss and possibly in the forming of a wet
patch. FIG. 7 shows an embodiment wherein the supply duct 4 coming
from outside is insulated. FIG. 7 shows the inner cavity wall 23,
insulating layer 24, ventilation gap 25 and outer cavity wall 26.
An insulating layer 27 is arranged on the underside of housing 19,
whereby the above stated drawbacks are avoided.
[0062] The warm supply and discharge ducts 2, 3 can also heat the
outer cavity wall 26. This can also be insulated, although the heat
loss is so small that it is not usually deemed necessary to apply
insulation for this purpose. If a larger hole in the wall is not a
problem, the pipe can be enclosed by a layer of insulating
material, for instance stiff foam.
[0063] For the purpose of maintaining comfort in the indoor space
moisture transfer between the outgoing and incoming airflow is
necessary, this being achieved by periodically alternating the
heat-exchanging channels of these airflows without changing in the
external airflows themselves. Accordingly, to a preferred
embodiment, valves are arranged on the outer and inner side of the
recuperator here having the configuration of an enthalpy
recuperator. These valves can be controlled to open and close so as
to thus realize the alternation of the channels. For the valves it
is attractive to make use of valves with a round configuration.
This makes it possible to alternate the airflows in the recuperator
by rotating the valves relative to the recuperator.
[0064] In a large number of cases it is possible to suffice with
four different positions of the valves, these being: a first and a
second position, which are taken up alternately during normal use
for the purpose of enthalpy recuperation; a bypass position so as
not to recover heat, and a closed position of the recuperator in
the case of calamities or when there is no wish for
ventilation.
[0065] FIG. 8 shows a further embodiment wherein round, rotatable
valves 28, 29 are placed on both sides of the recuperator. These
valves 28, 29 are configured for axial entry and exit of the
airflows. Valve 28 is subdivided into four axial segments, three of
which are numbered 30, 31, 32, and a central segment 33. Valve 29
is subdivided into four axial segments, three of which are numbered
34, 35, 36, and a central segment 33. Axial segments 30, 31 and 34,
35 are open and the axial radial segments 32, 36 are closed, as are
both central segments 33. Open segment 30 of valve 28 is connected
to the airflow from the room, open segment 31 of valve 28 is
connected to the airflow to the room, open segment 34 of rotating
valve 29 is connected to the airflow to the outside, open segment
35 of valve 29 is connected to the airflow from the outside. The
external channels and fans co-rotate with the associated valve.
FIG. 8 shows the valves in the second position.
[0066] As already elucidated with reference to FIG. 6, four supply
and discharge ducts 1, 2, 3, 4 and two bypass channels 18 are
present in housing 19 of the recuperator. In the embodiment shown
in FIG. 8 the valves 28, 29 are identical.
[0067] The different positions of valves 28, 29 are shown
schematically in FIG. 9. The figures in the left-hand column here
show the end surfaces of recuperator 7 and the subsequent columns
show the relevant valve in the above elucidated positions. The
upper series of figures shows the end surface and valve 29 of the
recuperator on the outer side and the lower series of figures shows
the end surface and valve 28 on the inner side. Each of the figures
shows the view or cross-section as seen from the inside.
[0068] The figures in the second column show the first position of
valves 28, 29. This shows how the discharge air from the dwelling
flows through open segment 30 of valve 28 to channel 1 and the
supply air to the dwelling flows from channel 2 via an open segment
31. The outside air flows through channel 4 to the recuperator via
an open segment 35. The used air from the dwelling leaves the
recuperator via channel 3 and an open segment 34. This is the first
position of the enthalpy recovery.
[0069] The figures in the third column of FIG. 9 show the second
position of valves 28, 29. Valve 28 on the inner side has been
rotated two segments)(-144.degree. relative to the first position,
whereby the supply air from the dwelling flows via open segment 31
to channel 1 and flows via open segment 30 from channel 2 out of
the room. Valve 29 on the outer side is also rotated two
segments)(-144.degree. relative to the first position. The outside
air is supplied via open segment 35 to channel 3 and the air from
channel 4 is carried outside via open segment 34. The flows inside
the actual recuperator are alternated here so that ice and
condensation formed in the heat-exchanging channels 5, 6 in the
previous position sublimates and evaporates.
[0070] The third position or the bypass position is shown in the
right-hand column of FIG. 9. Valve 28 is further rotated two
segment parts)(-144.degree. relative to the first position, whereby
the air from indoors flows through segment 30 to channel 2 and the
air from bypass channel 18 flows indoors through segment 31. Valve
29 has been rotated one segment relative to the first position 1
(72.degree.) as seen from the same side as valve 28. The outside
air is carried through segment 35 to bypass channel 18 and the flow
exiting channel 4 flows through segment 34 to the outside. The flow
from outside to inside hereby passes through the recuperator via
bypass channel 18, while the flow from inside to outside moves
through the recuperator but cannot absorb any heat, since there is
no flow on the other side of the recuperator. With this
configuration of the valves the recuperator cannot be closed.
[0071] As elucidated with reference to FIGS. 10 and 11, it is also
possible to close the recuperator in a fourth position by reducing
to one segment, close to valve 28, the segment 30 through which the
air from indoors flows into the recuperator and by increasing to
two segments 32 the closed part in the segment where the air flows
inside from the recuperator, and by reducing to one segment 34,
close to valve 29, the segment where the air from outside flows to
the recuperator and by increasing to two segments 36 the closed
part in the segment where the air flows to the outside from the
recuperator.
[0072] FIG. 11 also shows in the first column the views of the end
walls and in the other columns the views of valves 28, 29. FIG. 10
and the second column of FIG. 11 show the first position of valves
28, 29. The discharge air from the dwelling to the recuperator
flows through an open segment 30 to channel 1 and leaves the
recuperator through channel 3 and open segment 34. The air from
outside flows via open segment 35 to channel 4 of and leaves the
recuperator through channel 2 and flows to the dwelling through
open segment 31.
[0073] The second position of valves 28, 29 is shown in the third
column of FIG. 11. Valve 28 has been rotated one segment
(+72.degree.) relative to position 1 and valve 29 has not been
rotated. Indoor air flows via an open segment 30 of valve 28 into
channel 2 and exits the recuperator through channel 4 via open
segment 35 of valve 29 to the outside. Air from outside flows via
open segment 35 into channel 3 of the recuperator and the airflow
from channel 1 enters via an open segment 31. The flows have now
been alternated relative to position 1. On the outer side the fresh
and discharge air therefore flows through a different segment than
in position 1. This implies that the fans have to be arranged in
the indoor space because, in the case of one fan indoors and the
other one outdoors, they are connected to each other via one
channel and act counter to each other, while the other channel has
no fan.
[0074] The third position of the valves is shown in the fourth
column of FIG. 11. Valve 28 has been rotated one
segment)(-72.degree. counter-clockwise relative to position 1 and
valve 29 has been rotated two segments (144.degree.) clockwise.
Indoor air flows via an open segment 30 of valve 28 to the
left-hand bypass channel 18 and exits the recuperator via open
segment 34 of valve 29 to the outside. Air from outside enters
channel 3 via open segment 35 of valve 29 and the air exits channel
1 to indoors via open segment 31 of valve 28. The outgoing air
passes through the recuperator and the fresh air flows via the
recuperator, but no heat is transferred since there is no flow on
the other side.
[0075] Finally, the fifth column of FIG. 11 shows the fourth
position of the valves. Valve 28 has been rotated two
segments)(-144.degree. counter-clockwise relative to the first
position, while valve 29 has not been rotated relative to the first
position. The two closed segments 32 close the access to channels 1
and 2. Bypass channels 18 are open on the side of valve 28. The two
closed segments 36 of valve 29 close bypass channels 18. All
channels are closed in this valve position so that no air can be
exchanged between inside and outside.
[0076] Valves 28 and 29 are preferably driven individually by
motors 41, which can be accommodated in central segments 33 of the
valves.
[0077] In order to prevent leakage the seal between baffles 37 and
outer wall of valves 28, 29, housing 19 and the associated parts of
the recuperator has to be continuous. Sealing on the plane
perpendicularly of the axis of rotation between the valve and the
tube with baffles and recuperator is not precluded, but requires
great dimensional accuracy. An improvement is possible by applying
an O-ring 38 or a similar seal in a groove following the sealing
line in combination with a spring, which makes the valve compress
the seal. In order to eliminate the friction with the seal during
the rotation, the valve is moved in axial direction by having it
run over a radial cam track (65, 66), wherein the valve is pressed
onto the seal in the five rest positions and, outside these
positions, is raised axially such that there is no further contact
with the seal, as shown in FIG. 12. The seal is planar and the
lifting movement of the valve is perpendicular to this plane, so
that a very good seal can be realized.
[0078] In the above elucidated embodiment with axial inflow and
outflow the fans and the channels on the inner side and the outer
side co-rotate with the valve. This can be a drawback in some
applications. By allowing the air to flow in and out both axially
and radially as shown in FIG. 14, an embodiment is obtained wherein
the channels and the fans can be stationary. The housing of the
recuperator is provided on both sides with an extension 42, 43 in
which ports 44, 45 for radial inflow and outflow are arranged.
Valves 28, 29 are provided with a collar which extends parallel to
the extension and in which are arranged ports 46, 47 which can be
brought into overlap with ports 44, 45. As in the foregoing
embodiments, valves 28, 29 are each divided into segments by
baffles 37. The segment of the valve which is parallel to the cover
of the recuperator is open or closed.
[0079] Another embodiment has one valve, valve 28, as shown in FIG.
13. The housing of the recuperator is provided with an extension 42
in which port 44 for radial inflow and outflow is arranged. Valve
28 is provided with a collar which extends parallel to the
extension and in which are arranged ports 46 which can be brought
into overlap with port 44. As in the foregoing embodiments, valve
28 is divided into segments by baffles 37. The segment of the valve
which is parallel to the cover of the recuperator is open or
closed.
[0080] Within the above elucidated preconditions the present
invention provides four different secondary embodiments: [0081] A
first secondary embodiment with two identical valves and on either
side two ports which are the same, wherein the movement of valves
is independent and wherein the fans can be placed on both sides of
the recuperator. [0082] A second secondary embodiment with two
identical valves and two ports on one side and three ports on
another side, wherein the valves are not coupled and the fans can
be placed on both sides or on a single side. [0083] A third
secondary embodiment with two different valves and two ports on one
side and three ports on another side, wherein the movement of
valves is independent and the fans are placed on both sides or on
one side. [0084] A fourth secondary embodiment with one valve and
two ports on one side, wherein both fans are placed on the side of
the valve.
[0085] FIG. 15 shows similarly to FIGS. 9 and 11 the first
embodiment in the first position in the second column. The flow
from inside to outside moves axially via open segment 30 of valve
28 to channel 2 of the recuperator and exits the recuperator
axially through open segment 34 of valve 29 via channel 4. The flow
from outside to inside moves radially via the open port 45 of the
extension and the radial open port 47 of valve 29 to channel 3 of
the recuperator and exits the recuperator through channel 1 via an
open segment 46 of valve 28 and port 44 of the extension.
[0086] In the second position valves 28 and 29 are both rotated one
segment counter-clockwise relative to position 1. The flow from
inside to outside moves axially via open segment 30 of valve 28 to
channel 1 of the recuperator and exits the recuperator axially
through open segment 34 of valve 29 via channel 3. The flow from
outside to inside moves radially via port 45 in the extension and
open port 47 of valve 29 to channel 4 of the recuperator and exits
the recuperator through channel 2 radially via open port 46 of
valve 28 and radially via port 44 of the extension.
[0087] In the third position, the bypass position, valve 28 has
been rotated 144.degree. counter-clockwise relative to position 1
and valve 29 has been rotated 72.degree. clockwise. The flow from
inside to outside moves axially via open segment 30 of valve 28 to
the left-hand bypass channel 18, exits this channel axially through
open segment 34 of valve 29. The flow from outside to inside moves
radially via ports 45 of the extension and open ports 47 of valve
29 to channels 4 and 3 of the recuperator and exits the recuperator
radially through channels 1 and 2 via radial ports 46 of valve 28.
This embodiment uses the two heat-exchanging channels 5, 6 in
parallel, whereby the pressure drop is halved.
[0088] In the fourth position, the closed position, valve 28 has
been rotated 144.degree. clockwise relative to position 1 and valve
29 has also been rotated 144.degree. clockwise. Since channels 1
and 2 on the inner side as well as channel 3 on the outer side are
closed here, no air can move through the recuperator. The two
bypass channels 18 are also closed on both sides.
[0089] FIG. 16 shows in the same way as FIG. 15 the second
embodiment in all positions. This is a variation of the first
embodiment, wherein two identical valves are used in which one
segment is axially open and three segments are radially open. In
the first position the flow from inside to outside moves axially
via open segment 30 of valve 28 to channel 2 of the recuperator and
exits the recuperator via channel 4 and then radially through a
port 47 of valve 29 and port 45 of the extension. The flow from
outside to inside moves axially via open segment 34 of valve 29 to
channel 3 of the recuperator and exits the recuperator via channel
1 radially via port 46 of valve 28 and port 44 in the
extension.
[0090] In the second position valve 28 has been rotated 72.degree.
counter-clockwise relative to position 1 and valve 29 has been
rotated 72.degree. clockwise. The flow from inside to outside moves
axially via open segment 30 of valve 28 to channel 1 of the
recuperator and exits the recuperator through channel 3 and then
radially through port 47 of valve 29 and port 45 of the extension.
The flow from outside to inside moves axially via open segment 34
of valve 29 to channel 4 of the recuperator and exits the
recuperator via channel 2 and radially via port 46 of valve 28 and
port 44 of the extension.
[0091] In the third position valve 28 has been rotated 144.degree.
counter-clockwise relative to position 1 and valve 29 has not been
rotated. The flow from inside to outside moves axially via open
segment 30 of valve 28 to bypass channel 18 and exits this channel
radially through port 47 of valve 29 and port 45. The flow from
outside to inside moves axially via open segment 34 of valve 29 to
channel 3 of the recuperator and exits the recuperator via channel
1 and radially via port 46 of valve 28 and port 44 of the
extension.
[0092] In the fourth position valve 28 has been rotated 144.degree.
clockwise relative to position 1 and valve 29 has been rotated
144.degree. counter-clockwise. The respective open segments 30 and
34 of valves 28 and 29 have been rotated in front of the closed
segment of the recuperator, whereby no air flows in. Port 44 of the
extension and open segment 46 of valve 28 is connected to channel 2
of the recuperator and thereby to channel 4, where the closed
segment of valve 29 does not allow any connection to the outside.
Port 45 of the extension of valve 29 is connected to channel 3 of
the recuperator and thereby to channel 1, where the segment of
valve 28 is closed. An airflow between inside and outside is hereby
blocked.
[0093] The third embodiment applies when the valves are coupled or
when only the recuperator is rotated. In this embodiment the valves
are different, wherein valve 28 has two open radial segments and
one axial segment, while valve 29 has three open radial segments
and two axial segments, as shown in FIG. 1. In the first position
the flow from inside to outside moves axially via open segment 30
of valve 28 to channel 1 of the recuperator and exits the
recuperator via channel 3 and then radially through port 47 of
valve 29 and port 45 of the extension. The flow from outside to
inside moves axially via open segment 34 of valve 29 to channel 4
of the recuperator and exits the recuperator via channel 2 via port
46 of valve 28 and port 44 of the extension.
[0094] In the second position valve 28 has been rotated 72.degree.
clockwise relative to the first position and valve 29 is coupled so
that it has also been rotated 72.degree. clockwise, as shown in
FIG. 17. The flow from inside to outside moves axially via open
segment 30 of valve 28 to channel 2 of the recuperator and exits
the recuperator via channel 4 and radially via port 47 of valve 29
and port 45 of the extension. The flow from outside to inside moves
axially via open segment 34 of valve 29 to channel 3 of the
recuperator and exits the recuperator via channel 1 and radially
via port 46 of valve 28 and port 44 of the extension.
[0095] In the third position valve 28 has been rotated 72.degree.
counter-clockwise relative to the first position and valve 29 has
also been rotated 72.degree. counter-clockwise. The flow from
inside to outside moves axially via open segment 30 of valve 28 to
the left-hand bypass channel 18 of the recuperator and exits this
bypass channel radially through port 47 of valve 29 and port 45.
The flow from outside to inside moves axially via open segment 34
of valve 29 to channel 3 of the recuperator and exits the
recuperator via channel 1 and radially via port 46 of valve 28 and
port 44 of the extension.
[0096] In the fourth position, the closed position, valve 28 has
been rotated 144.degree. counter-clockwise relative to the first
position, and valve 29 has also been rotated 144.degree.
counter-clockwise. Open segment 30 of valve 28 has been rotated in
front of the closed segment of the recuperator, whereby no air
flows in. Open segments 46 of valve 28 do not connect to ports in
the extension of the housing. The open radial segments 47 of valve
29 are only connected to channels 3 and 4 of the recuperator and
thereby to channels 1 and 2, which connect to closed radial
segments of valve 28. An airflow between inside and outside is
hereby blocked.
[0097] The fourth embodiment applies when one valve is used, or
when only the recuperator is rotated. In this embodiment valve 28
has two open radial segments, as shown in FIG. 18. In the first
position the flow from inside to outside moves axially via open
segment 30 of valve 28 to channel 1 of the recuperator and exits
the recuperator via channel 3. The flow from outside to inside
moves via channel 4 of the recuperator and exits the recuperator
via channel 2 via port 46 of valve 28 and port 44 of the
extension.
[0098] In the second position valve 28 has been rotated 72.degree.
clockwise relative to the first position, as shown in FIG. 18. The
flow from inside to outside moves axially via open segment 30 of
valve 28 to channel 2 of the recuperator and exits the recuperator
via channel 4. The flow from outside to inside moves via channel 3
of the recuperator and exits the recuperator via channel 1 and
radially via port 46 of valve 28 and port 44 of the extension.
[0099] In the third position valve 28 has been rotated 72.degree.
counter-clockwise relative to the first position. The flow from
inside to outside moves axially via open segment 30 of valve 28 to
the left-hand bypass channel 18 of the recuperator. The flow from
outside to inside moves via channel 3 of the recuperator and exits
the recuperator via channel 1 and radially via port 46 of valve 28
and port 44 of the extension.
[0100] In position 4, the closed position, valve 28 has been
rotated 144.degree. counter-clockwise relative to the first
position. Open segment 30 of valve 28 is rotated in front of the
closed segment of the recuperator, whereby no air flows in. Open
segments 46 of valve 28 do not connect to ports in the extension of
the housing. An airflow between inside and outside is hereby
blocked.
[0101] As is the case with seal 38 of the valves with axial-axial
operation, a seal 38 can, in the case of the valves with
axial-radial operation, be arranged on the cover of the recuperator
with the same cam mechanism in order to lift the valve slightly
during rotation so that friction is avoided. An O-ring 48 can then
also be arranged on the other side of the valve for the purpose of
the seal on the tube, as shown in FIG. 19. For the seal of the
valve on the periphery of the tube, between the ports, it suffices
for the two parts to be produced with sufficient precision. If
valve and tube are insufficiently round, the fit can be made
slightly conical 50, 51. Should this still result in too much
leakage, an O-ring-like seal 49 can then be arranged in axial
direction between the ports. This seal is also released during
rotation by lifting the valve sufficiently in axial direction using
the proposed cam mechanism.
[0102] Application in window frames has the advantage that the
recuperator can already be arranged in the window frame factory and
need no longer be installed on site. Nor does a hole need to be
drilled, as in the solution through the wall. In addition to
replacing an old frame with a frame provided with a recuperator, as
will take place mainly in larger renovations, it is also possible
to place a casing with recuperator at the location where fan
gratings are now placed (usually above the windows).
[0103] Since the width of window frames is usually the largest
dimension, the recuperator is preferably also placed in the width
direction, wherein according to the invention the plates of the
recuperator are placed perpendicularly of the contact surface and
the stacking direction is substantially in the same direction as
the longitudinal direction of the tube in which it is placed. The
supply and discharge ducts extend over the recuperator
perpendicularly of the plates and run in cross-sectional area
substantially proportionally to the distance to the end of the
channel. The plates in the recuperator are preferably connected to
each other in each case with the same translation, so that an
oblique stack results with the same angle as the intended supply
ducts.
[0104] It is attractive to also provide these recuperators with
enthalpy valves 28, 29 and radial ports 44, 45, 46, 47. The same
valves can be applied here as in the initially described
recuperator for wall mounting. The first embodiment is recommended,
wherein the number of radial ports on both sides of the recuperator
amounts to two, the two ports lie adjacently of each other and are
rotated through 180.degree. relative to each other so that, by
rotating the recuperator through 90.degree., it falls within a
rectangle, the shortest side of which is equal to the diameter of
valves, whereby frame casing 60 can be given a compact
construction. FIG. 20 shows an arrangement in a frame casing above
the window.
[0105] The enthalpy valve with axial and radial inflow and outflow
according to the first embodiment is applied here, although other
embodiments are also possible. The fan for the supply of fresh air
52 is placed on the inner side, as is the fan for discharge 53.
This prevents clogging of the fan at temperatures far below
freezing point by snow formed from condensate. The supply duct for
fresh air to space 55 is provided with sound-damping material. The
discharge duct for indoor air 54 has an angle and is provided with
sound-damping material. A filter 58 is arranged in the supply duct
for outside air 57 in order to exclude contaminants from outside.
The discharge duct for outside air 56 can be provided with
sound-damping material.
[0106] The air which leaves the recuperator enters the discharge
duct with a velocity component perpendicular to the main flow in
this channel. This results in a concentration of the airflow at the
wall of the channel. The high velocity gradient at the wall results
in an additional pressure drop relative to that in the supply duct,
where the flow is divided almost logarithmically over the
cross-section. The amount of air flowing through the recuperator
channels is distributed unevenly because of this asymmetric
pressure distribution. An ideal recuperator has to have a uniform
distribution of the flow through the channels, since the
effectiveness would otherwise decrease.
[0107] In order to convert the velocity component toward the wall
to a component in the main flow direction in the discharge duct it
is recommended to apply vanes (61) at the beginning and end of
plates 9 of recuperator 7. The flow is hereby deflected, whereby
the velocity component in the main flow direction is greater than
that toward the wall of the discharge duct.
[0108] Although the vanes at the inflow are less important than at
the outflow, they are however important when the flow is reversed,
since inflow then becomes outflow. In addition to the vanes at the
beginning and end of the recuperator plates, guide vanes can also
be placed in the inflow and outflow channels, whereby the pressure
drop is distributed more uniformly over the length of the
channels.
[0109] In inflow channels 1, 4 the axial impulse of the air is
converted to dynamic pressure during inflow into heat-exchanging
channels 5, 6. In the case of outflow channels 2, 3 the air from
heat-exchanging channels 5, 6 has to be accelerated in axial
direction, for which purpose the dynamic pressure is used. The
overall pressure drop in outflow channels 2, 3 hereby becomes
greater than that in inflow channels 1, 4. This difference in
pressure drop causes a non-uniform flow through heat-exchanging
channels 5, 6. The difference can be compensated to a significant
extent not only by having the hydraulic diameter of channels 1, 2,
3, 4 vary in linear manner, but also by having the diameter
decrease more sharply along the distance to the zero point. In FIG.
21 this is shown with reference to a cross-section of the tube and
the recuperator. In the narrow part of supply and discharge ducts
1, 2, 3, 4 the wall of tube 19 is provided with a thickened portion
62, whereby the speed and the dynamic pressure of the medium
increase locally so that the pressure drop over heat-exchanging
channels 5, 6 becomes more uniform along the length of the
recuperator, the flow through these channels comes more equal and
the effectiveness of the recuperator increases. The same effect can
be obtained by providing the stack of plates with a corresponding
form.
[0110] Moistening of the plates is important for a good operation
of the enthalpy recuperation and for the purpose of forming
condensation when it becomes too humid indoors. This prevents
droplets partially or wholly blocking a channel. The pressure drop
due to condensate is hereby limited and the condensate is
discharged better under the influence of gravitational force. A
plastic such as impact-resistant polystyrene is preferably used for
the recuperator plates. The surface tension of most plastics is
high, so that drops adhering to the surface are formed. Mechanical
surface roughening only provides for a small decrease in the
surface tension and is difficult to apply in the required fine
roughness. The roughness usually disappears wholly or partially
during the subsequent thermoforming. In order to obtain the desired
nanostructure the surface is preferably treated with a PCVD
process, wherein SiO.sub.2 is applied in a layer thickness of
between 10 and 100 nm. Because the PCVD process takes place in a
vacuum chamber the plasma can cover the whole channel, which would
not be possible atmospherically. The thus formed very thin,
oriented SiO.sub.2 layer is very hydrophilic, so that a water
droplet is quickly spread over the surface. In the case of
condensation a water layer is formed which has a maximum thickness
in the order of 100 .mu.m and which flows out of the recuperator
under the influence of gravitational force. Tests show that
pressure drop, which doubles in the case of untreated material, now
increases by only .about.15%. In the enthalpy position not a
droplet escapes, and all the condensation evaporates in the
subsequent cycle. The switching time of the enthalpy cycle can be
increased owing to the better moistening, which reduces the virtual
leakage during switching.
[0111] The structure of the SiO.sub.2 layer is such that water
vapour is also adsorbed on the wall below the condensation
temperature, whereby the enthalpy transfer is increased. It is also
possible to make use of materials other than SiO.sub.2.
* * * * *