U.S. patent application number 13/903780 was filed with the patent office on 2013-11-28 for module, device and method for providing a fluid curtain.
This patent application is currently assigned to Norpe Oy. The applicant listed for this patent is Norpe Oy. Invention is credited to Kimmo Heinavaara, Tomi Sipila.
Application Number | 20130316635 13/903780 |
Document ID | / |
Family ID | 48576227 |
Filed Date | 2013-11-28 |
United States Patent
Application |
20130316635 |
Kind Code |
A1 |
Sipila; Tomi ; et
al. |
November 28, 2013 |
Module, Device and Method for Providing a Fluid Curtain
Abstract
A module with a flow channel for providing a fluid curtain, such
as an air curtain, between different environments, comprises an
inlet for introducing a fluid flow through said flow channel of the
module and an outlet for introducing said fluid curtain. In
addition the module comprises a honeycomb structure with plurality
of parallel conduits before the outlet in order to laminarize the
flow for the fluid curtain, and guiding the flow and suppressing
instabilities in the flow downstream of it. Furthermore the module
comprises a mechanical structure before the outlet. The mechanical
structure is configured to change the velocity profile of the flow
before the honeycomb structure or during the honeycomb structure so
that the velocity profile of the flow after the honeycomb structure
or outlet is a smooth skewed parabolic velocity profile with a peak
shifted from the centre line of the symmetrical parabolic velocity
profile.
Inventors: |
Sipila; Tomi; (Hyvinkaa,
FI) ; Heinavaara; Kimmo; (Valko, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Norpe Oy |
Porvoo |
|
FI |
|
|
Assignee: |
Norpe Oy
Porvoo
FI
|
Family ID: |
48576227 |
Appl. No.: |
13/903780 |
Filed: |
May 28, 2013 |
Current U.S.
Class: |
454/192 |
Current CPC
Class: |
F24F 9/00 20130101; A47F
3/0447 20130101 |
Class at
Publication: |
454/192 |
International
Class: |
F24F 9/00 20060101
F24F009/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 2012 |
FI |
20125567 |
Claims
1.-16. (canceled)
17. A module for providing a fluid curtain between different
environments, the module comprising: an inlet configured to
introduce a fluid into a flow channel of the module; an outlet for
the fluid, the outlet configured to create a fluid curtain between
different environments; a honeycomb structure located before the
outlet and configured to laminarize the flow of the fluid in the
fluid curtain, wherein the honeycomb structure comprises a
plurality of substantially parallel conduits configured to guide
the flow of the fluid and suppress instabilities in the flow of the
fluid; and a mechanical structure located before the outlet,
wherein the mechanical structure is configured to change the
velocity profile of the flow before or in the honeycomb structure
so that the velocity profile of the flow after the honeycomb
structure or the outlet comprises a skewed parabolic velocity
profile with a peak shifted from the center line of the symmetrical
parabolic velocity profile.
18. The module of claim 17, wherein the mechanical structure
comprises a deflector configured to guide the fluid flow from the
inlet to the honeycomb structure so that a greater dynamic pressure
and greater fluid velocity is introduced at a distance from the
center line of the honeycomb structure.
19. The module of claim 18, wherein the deflector comprises an
S-shaped or convex-shaped deflector.
20. The module of claim 18, wherein the form of the deflector
downstream of the inlet flow is convergent, continuously
convergent, or continuously but non-linearly convergent towards the
honeycomb structure.
21. The module of claim 18, wherein a first curve of the S-shaped
deflector or the peak of the convex-shaped deflector towards the
honeycomb structure is located downstream of the inlet flow before
the center line of the honeycomb structure.
22. The module of claim 21, wherein a second curve of the S-shaped
deflector in the opposite direction of the first curve is located
downstream of the inlet flow after the center line of the honeycomb
structure.
23. The module of claim 17, wherein the mechanical structure
comprises the honeycomb structure and wherein the cross sectional
area of the conduits of the honeycomb structure located in the
downstream direction of the inlet flow before the center line of
the honeycomb structure are greater than the diameter of the
conduits after the center line of the honeycomb structure.
24. The module of claim 17, wherein the fluid is air, nitrogen,
vapor, stream, or combinations thereof.
25. An apparatus, comprising: a display device containing a display
space and an access opening; and a module located in front of the
display space, the module configured to supply a fluid curtain
across the access opening, wherein the module comprises: an inlet
configured to introduce a fluid into a flow channel of the module;
an outlet for the fluid, the outlet configured to create a fluid
curtain between different environments; a honeycomb structure
located before the outlet and configured to laminarize the flow of
the fluid in the fluid curtain, wherein the honeycomb structure
comprises a plurality of substantially parallel conduits configured
to guide the flow of the fluid and suppress instabilities in the
flow of the fluid; and a mechanical structure located before the
outlet, wherein the mechanical structure is configured to change
the velocity profile of the flow before or in the honeycomb
structure so that the velocity profile of the flow after the
honeycomb structure or the outlet comprises a skewed parabolic
velocity profile with a peak shifted from the center line of the
symmetrical parabolic velocity profile.
26. The apparatus of claim 25, wherein the mechanical structure
comprises a deflector configured to guide the fluid flow from the
inlet to the honeycomb structure so that a greater dynamic pressure
and greater fluid velocity is introduced at a distance from the
center line of the honeycomb structure.
27. The apparatus of claim 26, wherein the deflector comprises an
S-shaped or convex-shaped deflector.
28. The apparatus of claim 26, wherein the form of the deflector
downstream of the inlet flow is convergent, continuously
convergent, or continuously but non-linearly convergent towards the
honeycomb structure.
29. The apparatus of claim 26, wherein a first curve of the
S-shaped deflector or the peak of the convex-shaped deflector
towards the honeycomb structure is located downstream of the inlet
flow before the center line of the honeycomb structure.
30. The apparatus of claim 29, wherein a second curve of the
S-shaped deflector in the opposite direction of the first curve is
located downstream of the inlet flow after the center line of the
honeycomb structure.
31. The apparatus of claim 25, wherein the mechanical structure
comprises the honeycomb structure and wherein the cross sectional
area of the conduits of the honeycomb structure located in the
downstream direction of the inlet flow before the center line of
the honeycomb structure are greater than the diameter of the
conduits after the center line of the honeycomb structure.
32. The apparatus of claim 25, wherein the fluid is air, nitrogen,
vapor, stream, or combinations thereof.
33. A method for providing a fluid curtain between different
environments, the method comprising: introducing a fluid flow into
an inlet of a module, the module comprising an outlet configured to
create a fluid curtain between different environments; laminarizing
the fluid flow of the fluid curtain via a honeycomb structure which
contains a plurality of substantially parallel conduits configured
to guide the flow of the fluid and suppress instabilities in the
flow of the fluid; and changing the velocity profile of the flow
before or in the honeycomb structure so that the velocity profile
of the flow after the honeycomb structure or the outlet comprises a
skewed parabolic velocity profile with a peak shifted from the
center line of the symmetrical parabolic velocity profile.
34. The method of claim 33, wherein the velocity profile is changed
by a deflector configured to guide the fluid flow from the inlet to
the honeycomb structure so that a greater dynamic pressure and
greater fluid velocity is introduced at a distance from the center
line of the honeycomb structure.
35. A method of claim 33, wherein the cross sectional area of the
conduits of the honeycomb structure located in the downstream
direction of the inlet flow before the center line of the honeycomb
structure is greater than the diameters of the conduits after the
center line of the honeycomb structure.
36. The method of claim 33, wherein the fluid is air, nitrogen,
vapor, stream, or combinations thereof.
Description
FIELD
[0001] The invention relates to a module, method and arrangement
for providing a fluid curtain, such as an air curtain, between
different environments, such as between two spaces with different
temperatures and/or concentrations.
BACKGROUND
[0002] Devices with fluid curtains separating two different
environments having common opening interface but different
conditions, such as temperature or concentration, are previously
known for example in technical fields of refrigeration apparatuses
but also a clean work area. The separation barrier is needed to
minimize the mixing of different conditions with each other, such
as temperature, different types of particles like microbes,
concentration or the like. It is noticed that entrained ambient air
into the cold air curtain in the refrigeration apparatuses is the
largest thermal load of a multi-deck type or "vertical"
refrigerated display case and according to some estimates 75% of
the refrigeration load comes from the air curtain entrainment. In
addition different types of air curtains are also used in laminar
air flow work stations, such as is described in U.S. Pat. No.
4,927,438 A.
[0003] As an example the patent publication U.S. Pat. No. 7,162,882
B2 (see Prior Art FIG. 1) discloses a multi-band air curtain
forming a separation barrier at an interface between a first
environment having a fluid at a first condition and a second
environment having a fluid at a second condition. A first stream
(55) of a fluid is directed along a first path generally parallel
to the interface between the first environment and the second
environment. A second stream (65) of fluid is directed along a
second path generally outwardly at an angle of divergence with the
first path. A third stream (85) of a fluid is directed along a
third path between the first path and the second path. A
refrigerated merchandiser (10) is also disclosed having a display
case having an interior defining a product display region (30)
having an open front and first (34), second (70) and third (68) air
outlets for directing air streams across the open front of the
refrigerated merchandiser.
[0004] There are however some disadvantages relating to the known
prior art, such as turbulent transition layer between the air
curtain and at least another environment. The more turbulent
transition layer the more entrainment of the ambient air into the
air curtain occurs. In addition the need of at least two or even
more air curtains is clear disadvantage.
SUMMARY
[0005] An object of the invention is to alleviate and eliminate the
problems relating to the known prior art. Especially the object of
the invention is to provide a method and module for providing a
fluid curtain between different environments such as environments
with different temperatures, contents and/or concentrations, like
bacterial content, so that the entrainment of the ambient fluid
into the fluid curtain is minimized.
[0006] The object of the invention can be achieved by the features
of independent claims.
[0007] The invention relates to a module according to claim 1. In
addition the invention relates to an arrangement of claim 7, and
method of claim 8.
[0008] According to an embodiment of the invention a fluid curtain,
such as an air curtain, between different environments is provided
via a honeycomb structure comprising plurality of parallel
conduits. The conduits are configured to laminarize the flow for
the fluid curtain, and to guide the flow and suppressing
instabilities in the flow downstream of it. The suppressing of
instabilities is performed at least in perpendicular direction to
walls of said conduits. According to an example the Reynolds number
of flow when flowing out from the honeycomb structure is
advantageously below 6000, more advantageously below 5000 and most
advantageously around 1000. However, it is to be noted that these
ranges or values are only examples and that the invention is not
limited only to those.
[0009] In addition according to an embodiment the velocity profile
of the flow before the honeycomb structure or during the honeycomb
structure is changed so that the velocity profile of the flow after
the honeycomb structure is a (advantageously smooth) skewed
parabolic velocity profile with a peak shifted from the centre line
of the symmetrical parabolic velocity profile. According to an
exemplary embodiment the peak is shifted towards the first
environment, such as towards inside of the refrigerated display
case. The invention offers clear advantages over the known prior
art, when the inventors have noticed that the shape of vertical
velocity profile and the turbulence intensity present at the outlet
nozzle will remarkably control the fluid curtain entrainment rate.
For example when applying the velocity profile as proposed by the
present invention the relative velocity and change of relative
velocity in the transition layer with the second environment fluid
(such as warm ambient air) is small, which keeps the transition
layer with the second environment fluid as laminar as possible
thereby minimizing entrainment of the ambient fluid into the fluid
curtain. By minimizing the entrainment of the ambient fluid the
thermal or particle load of the systems and thereby the
refrigeration or cleaning costs of the display case can be
remarkable reduced.
[0010] The term entrainment is used in this document for example to
the purpose of to transfer air or other fluid (or even particles)
into an organized fluid current (such as an air curtain) from the
surrounding atmosphere.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Next the invention will be described in greater detail with
reference to exemplary embodiments in accordance with the
accompanying drawings, in which:
[0012] FIG. 1 illustrates a prior art device for providing air
curtains;
[0013] FIG. 2 illustrates an exemplary module for providing fluid
curtain according to an advantageous embodiment of the invention;
and
[0014] FIG. 3 illustrates an exemplary arrangement (a refrigerated
display case) for providing fluid curtain according to an
advantageous embodiment of the invention.
DETAILED DESCRIPTION
[0015] FIG. 1 illustrates a prior art device for providing air
curtains described in U.S. Pat. No. 7,162,882 B2. FIG. 1 is already
handled in connection with the background of the invention chapter
above. Anyway it is to be understood that the module and inventive
concept of the present invention can also be implemented with
similar devices as described in FIG. 1, where the air curtain
providing means can be replaced for example by the module of the
invention described in FIG. 2 or with the means of said module,
such as an appropriate mechanical structure before the outlet for
the air curtain, where said mechanical structure is configured to
change the velocity profile of the flow before the honeycomb
structure or during the honeycomb structure so that the velocity
profile of the flow after the honeycomb structure or outlet is a
smooth skewed parabolic velocity profile with a peak shifted from
the centre line of the symmetrical parabolic velocity profile.
[0016] FIG. 2 illustrates an exemplary module 100 for providing a
fluid curtain, and especially an air curtain 101 between different
environments (Environment I, Environment II) according to an
advantageous embodiment of the invention, where the module
comprises a flow channel 102. The module 100 comprises an inlet 103
for introducing an air flow through the flow channel of the module
and an outlet 104 for outputting said air curtain. In addition the
module 100 comprises a honeycomb structure 105 before the outlet in
order to laminarize the flow for the air curtain. The honeycomb
structure comprises plurality of parallel conduits 106 for guiding
the flow and suppressing instabilities in the flow downstream of it
and at least in perpendicular direction to walls of said conduits
106.
[0017] In addition the module 100 comprises a mechanical structure
105, 107 before the outlet 104, which is configured to change the
velocity profile of the flow 101 before 107 the honeycomb structure
or during 105 the honeycomb structure so that the velocity profile
of the flow after the honeycomb structure 105 or outlet 104 is a
smooth skewed parabolic velocity profile with a peak 108 shifted
from the centre line 109 of the symmetrical parabolic velocity
profile or the centre line 109 of the honeycomb structure 105.
[0018] According to an embodiment the mechanical structure before
the outlet is a deflector 107, such as an S-shaped (described in
FIG. 2) or convex-shaped deflector, where the convex is configured
to protrude towards the honeycomb structure (not shown in Figures).
The deflector 107 is advantageously configured to guide the air
flow 110 from the inlet 103 to the honeycomb structure 105 so that
greater dynamic pressure and thereby the greater fluid velocity is
introduced to the distance from the centre line 109 of the
honeycomb structure, and most advantageously so that the greater
dynamic pressure and thereby greater fluid velocity is introduced
to the point before the centre line 109 of the honeycomb structure
in the direction of the inlet flow 103.
[0019] According to an embodiment the form of the deflector 107 in
the downstream direction 110 of the inlet flow is convergent,
advantageously continuously convergent, and most advantageously
continuously but non-linearly convergent towards the honeycomb
structure 105. Due to the rounded shapes and smooth surface of the
deflector 107 it does not significantly generate turbulence in flow
upstream of the honeycomb structure 105, In addition the honeycomb
structure 105 itself is a very effective device to suppress the
fluid curtain instabilities immediately downstream of it.
[0020] In addition according to an embodiment the first curve 107a
of the S-shaped deflector 107 or the peak or apex of the
convex-shaped deflector (not shown) is configured to protrude
towards the honeycomb structure 105 is located in the downstream
direction of the inlet flow 110 before the centre line 109 of the
honeycomb structure 105. Furthermore, according to an embodiment
the second curve 107b of the S-shaped deflector 107 is configured
to protrude into the opposite direction than the first curve, and
is located in the downstream direction of the inlet flow 110 after
the centre line 109 of the honeycomb structure 105. According to
these embodiment the greater dynamic pressure and thereby the
greater fluid velocity can be introduced to the point before the
centre line 109 of the honeycomb structure in the direction of the
inlet flow 103, and thereby the smooth skewed parabolic velocity
profile with a peak 108 shifted from the centre line 109 of the
symmetrical parabolic velocity profile or the centre line 109 of
the honeycomb structure 105 can be achieved, as is described in
FIG. 2.
[0021] According to an embodiment the mechanical structure before
the outlet 104 is the honeycomb structure 105 with plurality of
parallel conduits 106, wherein the cross sectional area of the
conduits of the honeycomb structure 105 located in the downstream
direction of the inlet flow 110 before the centre line 109 of the
honeycomb structure 105 is greater than the diameters of the
conduits after the centre line 109 of the honeycomb structure. Also
according to this embodiment the smooth skewed parabolic velocity
profile with a peak 108 shifted from the centre line 109 of the
symmetrical parabolic velocity profile or the centre line 109 of
the honeycomb structure 105 can be achieved, as is described in
FIG. 2.
[0022] FIG. 3 illustrates an exemplary arrangement 200, such as a
refrigerated display case, for providing fluid curtain according to
an advantageous embodiment of the invention. The device may
comprise a display space 201, an access opening 202 in the front of
said display space, and a flow curtain providing means 100 for
establishing the flow curtain 101 across the access opening 202.
Even if the refrigerated display case is described here as an
example, it is to be noted that the inventive concept, namely the
module 100 or the means and features 101-110 of the module
described e.g. in FIG. 2 can be utilized also in other devices
separating at least two different environments with the fluid
curtain, such as laminar air flow work stations.
[0023] The refrigerated display case 200 described in FIG. 3
comprises only one means for producing the fluid curtain, such as
only one channel 102, and therefore only one fluid curtain 101. In
addition the device 200 comprises a fluid suction means or portion
203 located adjacent the lower edge of the access opening 202, an
air duct 204 communicating with said fluid suction means or portion
203 having a fluid discharge outlet 205 near the upper edge of the
access opening 202.
[0024] The deflector 107 and the honeycomb structure 105, 106
described e.g. in connection with FIG. 2 can be implemented in
connection with the fluid discharge opening 205 to provide the
fluid curtain 101. However, it is to be noted that the deflector
107 and the honeycomb structure 105, 106 described e.g. in
connection with FIG. 2 can also be implemented into the device
described in FIG. 1 or 3 as a module described e.g. in connection
with FIG. 2.
[0025] In addition the device 200 advantageously comprises
circulating means 206 for circulating fluid through said fluid duct
204, 205 and again through the deflector 107 and the honeycomb
structure 105, 106, as well as through the refrigeration means 207
for example for refrigerating the fluid for the fluid curtain
101.
[0026] The device 200 described in FIG. 3 is a recirculated type
refrigerated display case, since it comprises the fluid suction
means or portion 203 for collecting the chilled fluid of the fluid
curtain 101 and recirculating it again. However, the inventive
concept and embodiments of the present invention can also be
implemented in connection with non-recirculated type devices, such
as is described in FIG. 1, where the refrigerated display case
comprises also one or more fans 72 or the like to draw ambient air
from the environment exterior of the refrigerator 10 through the
fluid duct 74 to the second air discharge outlet 70.
[0027] According to an advantageous embodiment the flow curtain 101
is created by forcing chilled flow in the duct 205 at the top of
the display case 200 into the deflector 107, such as S-shaped
deflector. The deflector 107 turns the chilled fluid flow 110
downward through the honeycomb structure 105 and thereby produces a
smooth skewed parabolic velocity profile with peak shifted towards
the inside of the display case 200 having low temperature
(Environment I) compared to the ambient temperature (Environment
II).
[0028] The invention has been explained above with reference to the
aforementioned embodiments, and several advantages of the invention
have been demonstrated. It is clear that the invention is not only
restricted to these embodiments, but comprises all possible
embodiments within the inventive idea and scope of the inventive
thought and the following patent claims. For example the different
environments separated by the fluid curtain comprise different
conditions, such as temperatures, bacterial contents, humidity,
concentration or the like. In addition even though the air curtain
is described as an example of the fluid curtain, the same inventive
concept can also be applied with other fluids for providing other
type fluid curtain, such as gas, like nitrogen, gas mixture or
vapour or stream.
* * * * *