U.S. patent application number 15/983232 was filed with the patent office on 2018-11-22 for ventilation unit for refrigeration plants.
The applicant listed for this patent is ebm-papst Mulfingen GmbH & Co. KG. Invention is credited to Daniel Gebert, Oliver Haaf, Thomas Heli.
Application Number | 20180335244 15/983232 |
Document ID | / |
Family ID | 61497789 |
Filed Date | 2018-11-22 |
United States Patent
Application |
20180335244 |
Kind Code |
A1 |
Haaf; Oliver ; et
al. |
November 22, 2018 |
Ventilation Unit For Refrigeration Plants
Abstract
A ventilation unit (1) designed for installation and use at a
refrigeration plant has a fan and a heat exchanger (3) arranged in
series with the fan. The fan is designed and positioned with regard
to the heat exchanger (3) so as it delivers, in operation, an air
volume flow through the heat exchanger (3) and out from the
ventilation unit. The fan is designed as a diagonal fan (2). The
diagonal fan axially draws in the air volume flow during operation
and blows it out diagonally at an angle relative to its axis of
rotation (RA).
Inventors: |
Haaf; Oliver; (Kupferzell,
DE) ; Heli; Thomas; (Langenburg, DE) ; Gebert;
Daniel; (Ohringen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ebm-papst Mulfingen GmbH & Co. KG |
Mulfingen |
|
DE |
|
|
Family ID: |
61497789 |
Appl. No.: |
15/983232 |
Filed: |
May 18, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/281 20130101;
F24F 11/43 20180101; F25B 13/00 20130101; F04D 17/06 20130101; F24F
1/0025 20130101; F25D 2500/02 20130101; F25B 39/00 20130101; F25D
17/067 20130101; F25D 2317/0681 20130101 |
International
Class: |
F25D 17/06 20060101
F25D017/06; F25B 13/00 20060101 F25B013/00; F25B 39/00 20060101
F25B039/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 19, 2017 |
DE |
102017111001.1 |
Claims
1-13. (canceled)
14. A ventilation unit designed for installation and use at a
refrigeration plant comprising: a fan and a heat exchanger arranged
in series with the fan, the fan is designed and positioned with
regard to the heat exchanger so as to deliver, in operation, an air
volume flow through the heat exchanger and out from the ventilation
unit; the fan is designed as a diagonal fan, the diagonal fan
axially draws in the air volume flow during operation and blows it
out diagonally at an angle relative to its axis of rotation (RA);
and the heat exchanger is designed to cool the air volume flow down
to a mean delivery temperature of .ltoreq.15.degree. C. in order to
form a cold air volume, and the cold air volume flow can be
directly drawn in and blown out by the diagonal fan.
15. The ventilation unit as claimed in claim 14, wherein the
diagonal fan is designed to draw in the air volume flow axially and
to blow it out diagonally at an angle of 10.degree.-80.degree.,
especially an angle of 25-60.degree. with respect to its axis of
rotation (RA).
16. The ventilation unit as claimed in claim 14, wherein the
diagonal fan is designed and arranged in the ventilation unit to
draw in the air volume flow axial through the heat exchanger and to
blow it out from the ventilation unit into the free
surroundings.
17. The ventilation unit as claimed in claim 14, wherein the heat
exchanger for the diagonal fan generates, by progressive frosting
during operation, a flow resistance increasing from a starting flow
resistance with a first resistance characteristic (A) to a frosting
resistance with a second resistance characteristic (B) and the
diagonal fan is designed to have its highest efficiency range in an
area of a third resistance characteristic (C) of the heat
exchanger, wherein the third resistance characteristic (C) lies
between the first and the second resistance characteristic (A, B),
and the resistance characteristics (A, B, C) are characterized by
an increasing backpressure psf [Pa] plotted against a delivered air
quantity qv [m3/h].
18. The ventilation unit as claimed in claim 14, wherein the
diagonal fan and the heat exchanger are joined together by a
housing, the housing forms a closed flow duct for the air volume
flow.
19. The ventilation unit as claimed in claim 14, wherein the
ventilation unit is designed as an integrated structural unit for
complete arrangement and fastening on the refrigeration plant.
20. The ventilation unit as claimed in claim 14, wherein the heat
exchanger is designed as an evaporator.
21. The ventilation unit as claimed in claim 14, further comprising
a guide device, the guide device is arranged in a blowout portion
of the diagonal fan and designed to deflect the air volume flow
blown out by the diagonal fan in a diagonal direction into an axial
direction.
22. The ventilation unit as claimed in claim 21, wherein the guide
device is designed as a single piece on the diagonal fan.
23. The ventilation unit as claimed in claim 20, wherein the guide
device is designed to transform a spin of the air volume flow
produced by the diagonal fan partly into static pressure.
24. The ventilation unit as claimed in claim 14, wherein the
diagonal fan has a co-rotating cover disk.
25. The ventilation unit as claimed in claim 18, wherein the
housing forms an air guidance for the air volume flow produced by
the diagonal fan.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to German Application No.
102017111001.1, filed May 19, 2017. The disclosures of the above
application is incorporating herein by reference.
FIELD
[0002] The disclosure relates to a ventilation unit designed for
installation and use at a refrigeration plant.
BACKGROUND
[0003] One problem, at refrigeration plants, with the use of
ventilation units having fans and heat transfer units, often called
heat exchangers, is the fact that the heat exchanger becomes
continuously frosted during its operation. Therefore, flow
resistance increases. The downstream fan must work against the
increasing flow resistance, so that its operating state is altered.
Traditionally, axial fans or axial ventilators are used in such
ventilation units. They are designed for flow resistance of the
heat exchanger without frosting. As a result, the fan is only
operated for a short time in the range of optimal efficiency.
However, with increasing frosting of the heat exchanger and its
increasing flow resistance, the operating state of the fan is moved
away from the optimal efficiency range. Furthermore, due to the
increased flow resistance, the outflow direction changes from an
axial to an increasingly radial direction.
[0004] Besides the worse plant efficiency in economic terms, it is
also a disadvantage from the standpoint of fluidics, since the
throw of the fan is greatly reduced, resulting in an uneven
temperature distribution in the cold room adjacent to the fan.
Furthermore, radially blown air is partly delivered around the
increasingly frosted heat exchanger and back to its inlet zone.
Once again, the air is taken through the heat exchanger and
produces a thermal short circuit.
[0005] Typically, a protective grille is located at the blowout
side of the fan. In this zone, with increasing radial outflow of
the axial fan, the very cold air mixes with the air of the
adjoining cold room (back flow in the hub region). In applications
with high humidity, ice or snowlike material may become deposited
on the fan blades or the protective grille. This likewise worsens
the efficiency and the flow characteristics. Furthermore, when the
heat exchanger is being defrosted and the fan is standing still,
the ice may drop onto the wall ring of the fan and prevent a
restarting of the fan due to frosting.
[0006] The necessary defrosting is generally a disadvantageous and
costly disruption of the proper operation, one to be avoided as
much as possible.
[0007] The problem that the disclosure proposes to solve is,
therefore, to provide a ventilation unit that overcomes the above
drawbacks and can be operated more efficiently, as well as with
less frequent defrosting.
SUMMARY
[0008] This problem is solved by a ventilation unit designed for
installation and use at a refrigeration plant. The ventilation unit
includes a fan and a heat exchanger, arranged in series with the
fan. The fan is designed and positioned with regard to the heat
exchanger so as to deliver, in operation, an air volume that flows
through the heat exchanger and out from the ventilation unit. The
fan is designed as a diagonal fan. The diagonal fan axially draws
in the air volume flow during operation and blows it out diagonally
at an angle relative to its axis of rotation (RA). The heat
exchanger is designed to cool the air volume flow down to a mean
delivery temperature of .ltoreq.15.degree. C. in order to form a
cold air volume. The cold air volume flow can be directly drawn in
and blown out by the diagonal fan.
[0009] According to the disclosure, a ventilation unit is designed
for installation and use at a refrigeration plant. A fan and a heat
exchanger are arranged in series with the fan. The fan is designed
and positioned with regard to the heat exchanger so as to deliver,
in operation, an air volume flow through the heat exchanger and out
the ventilation unit. The fan is designed according to the
disclosure as a diagonal fan. In the diagonal fan, the air volume
flow during operation is drawn in axially and blown out diagonally
at an angle relative to the axis of rotation of the diagonal
fan.
[0010] The diagonal ventilator is advantageously distinguished by a
high air output even with large backpressure. This ensures that the
blowout direction of the diagonal ventilator is always diagonal and
not radial, even if maximum backpressures occurs during operation.
Its throw also remains substantially the same without change, even
with a continuously increasingly frosted heat exchanger. Thus, a
thermal short circuit is prevented due to backflow at the outlet to
the intake zone of the heat exchanger. Furthermore, this prevents a
further frosting of the heat exchanger as a result. The defrost
cycles of the heat exchanger become longer.
[0011] In one advantageous variant embodiment, the diagonal fan is
designed to draw in the air volume flow axially and to blow it out
diagonally at an angle of 10-80.degree., and, more preferably, at
an angle of 25-60.degree. with respect to its axis of rotation. As
compared to a 0.degree. blowout angle of an axial fan and a
90.degree. blowout angle of a radial fan, the blowout angle of the
diagonal fan affords a middle value from the outset, that can be
maintained throughout the operation.
[0012] One favorable embodiment of the ventilation unit proposes
that the diagonal fan is designed to draw in the air volume flow
axially through the heat exchanger and to blow it out from the
ventilation unit into the free surroundings, for example in a cold
room. The diagonal fan is therefore fluidically connected
downstream from the heat exchanger.
[0013] The heat exchanger generates, by progressive frosting for
the diagonal fan during operation, a flow resistance increasing
from a starting flow resistance with a first resistance
characteristic (A) to a frosting resistance with a second
resistance characteristic (B). One advantageous embodiment of the
ventilation unit is characterized in that the diagonal fan is
designed to have its highest efficiency range in an area of a third
resistance characteristic (C) of the heat exchanger. The third
resistance characteristic lies between the first and the second
resistance characteristic (A, B). The resistance characteristics
(A, B, C) are characterized by an increasing backpressure psf [Pa]
plotted against a delivered air quantity qv [m3/h]. The outflow,
even at maximum backpressures, also always remains diagonal and
does not change in a radial direction, such as with axial fans.
[0014] According to the disclosure, the heat exchanger is designed
to cool the air volume flow down to a mean delivery temperature
less than or equal to 15.degree. C., especially 5.degree. C., in
order to form a cold air volume. The cold air volume flow can be
directly drawn in and blown out by the diagonal fan. Between the
heat exchanger and the diagonal fan there are no components
thermally influencing the cold air volume flow. The intake by the
diagonal fan occurs immediately downstream from the heat
exchanger.
[0015] The ventilation unit in one embodiment is characterized in
that the diagonal fan and the heat exchanger are joined together by
a housing. This forms a closed flow duct for the air volume flow or
the cold air volume flow.
[0016] Moreover, it is also advantageous for the ventilation unit
to be designed as an integrated structural unit for complete
arrangement and fastening on the refrigeration plant. The
integrated component can be pre-assembled as a whole and delivered.
At the cold room, only the electrical hook-up needs to be done.
This reduces the likelihood of mistakes during the installation
process.
[0017] In one advantageous embodiment, the heat exchanger is
designed as an evaporator.
[0018] In one modification, the ventilation unit moreover comprises
a flow guide device. It is arranged in a blowout portion of the
diagonal fan and is designed to deflect the air volume flow blown
out by the diagonal fan in a diagonal direction into an axial
direction. The diagonal blowout direction of the diagonal fan may
in this way be diverted into an axial blowout direction. Hence, the
throw of the diagonal fan is increased. The guide device can be
realized by parts of the housing or by guiding bodies secured
additionally on the diagonal fan, such as air baffles or the like.
In one variant embodiment, the guide device is designed as a single
piece on the diagonal fan. Thus, the number of parts is
minimized.
[0019] In addition, a protective grille or access barrier may be
arranged on the diagonal fan at the blowout side.
[0020] Moreover, it may be provided, in the ventilation unit, that
the guide device transforms the spin of the air volume flow
produced by the diagonal fan partly into static pressure and
thereby boosts the pressure increase, efficiency, and throw of the
diagonal fan.
[0021] Moreover, in one variant embodiment the diagonal fan has a
co-rotating cover disk covering the fan blades.
[0022] The ventilation unit in one sample embodiment may
furthermore be designed such that the flow guidance occurs in the
stationary housing and the diagonal fan has an axial fanlike wing
tip. A gap is then formed between the impeller and the fan
blades.
[0023] Other advantageous modifications of the disclosure will be
presented in further detail below, together with the description of
the preferred embodiment of the invention with the aid of the
figures.
DRAWINGS
[0024] FIG. 1 is a cross-section schematic view of a ventilation
unit not pertaining to the disclosure with an axial fan of the
prior art to illustrate the flow behavior in the frosted state;
[0025] FIG. 2 is a cross-section schematic view of the ventilation
unit of FIG. 1 in a state without frosting;
[0026] FIG. 3 is a cross-section schematic view of a ventilation
unit according to the disclosure in the frosted state; and
[0027] FIG. 4 is a diagram to show the design of the ventilation
unit according to the disclosure.
DETAILED DESCRIPTION
[0028] FIG. 1 shows the basic schematic layout of the ventilation
unit according to the disclosure, but with an axial fan 11
connected to a heat exchanger 10, in order to illustrate the
fluidic problems. FIG. 1 shows a frosted state of the heat
exchanger 10 and a resulting substantially radial outflow of the
axial fan 11. A thermal short circuit is produced on the flow path
8 represented by arrows. Air is blown out from the axial fan 11 and
returns once more to the intake zone of the heat exchanger.
Furthermore, an inflow 9 occurs at the blowout side in the hub zone
of the axial fan 11, on which the outflow is superimposed. In the
frosted state of the heat exchanger, little or nothing remains of
the actual purely axial outflow provided in the nonfrosted state,
as shown for example in FIG. 2.
[0029] FIG. 3 shows schematically a ventilation unit 1 according to
the disclosure in the frosted state with a diagonal fan 2 and a
heat exchanger 3, designed as an evaporator, arranged in series
with it. The heat exchanger 3 and the diagonal fan are joined
together by a housing 5. The housing 5 forms a flow duct. Both the
diagonal fan 2 and the heat exchanger 3 are installed and secured
in the housing 5. Thus, the ventilation unit is an integrated
structural unit. On the blowout portion of the diagonal ventilator
2, a protective grille is arranged. The ventilation unit 1 in its
schematically represented form is designed for installation and use
at a refrigeration plant.
[0030] In operation, the diagonal fan 2 draws in an air volume flow
from the axial direction through the heat exchanger 3. The diagonal
fans blows out the air despite frosting, from the ventilation unit
1 diagonally in an angle .alpha.=30.degree. with respect to the
axis of rotation RA of the diagonal fan 2 into the open
surroundings, such as a cold chamber. The diagonal outflow path 7
is indicated by arrows.
[0031] The heat exchanger 3 cools the air volume flow down to a
mean delivery temperature equal to or less than 15.degree. C.,
especially equal to or less than 5.degree. C., in order to form the
cold air volume flow, which is taken in directly by the diagonal
fan 2.
[0032] The ventilation unit 1 according to the disclosure in FIG. 3
with the diagonal fan 2 may be interpreted, as compared to the
embodiment with an axial fan 10 represented in FIG. 1, in the
manner shown in FIG. 4 with the aid of a diagram of the delivered
air volume qv [m3/h] plotted against the pressure psf [Pa]. The fan
characteristics 11', 2' of the axial fan 11 of FIG. 1, the diagonal
fan 2 of FIG. 3, as well as three resistance characteristic curves
A, B, C due to different frosting states of the heat exchanger 3,
are plotted in FIG. 4.
[0033] The flow resistance of the heat exchanger 3 increases during
operation by progressive frosting from a starting flow resistance
with a first resistance characteristic A for the diagonal fan to a
frosting resistance with a second resistance characteristic B. In
the state of the second resistance characteristic, a defrosting
process is initiated for the heat exchanger 3. The diagonal fan 2,
on the other hand, is designed such by its diagonal blowout
direction that it has its highest efficiency range in a region of
the third resistance characteristic C of the heat exchanger 3. The
third resistance characteristic C lies between the first and second
resistance characteristic A, B. The resistance characteristics A,
B, C are characterized by an increasing backpressure psf [Pa]
plotted against the delivered air volume qv [m3/h].
[0034] The ventilation unit 1 according to the disclosure with the
diagonal fan 2 can be operated for a longer time and with higher
efficiency in the region of the resistance characteristic C for the
same corresponding delivery volume, as compared to a layout with
the axial fan 11. The axial fan 11 only functions per design in the
region of the resistance characteristic A. The absolute difference
is indicated in the diagram by the fan characteristic curves 11',
2' of the axial fan 11 and diagonal fan 2.
* * * * *