U.S. patent application number 11/017614 was filed with the patent office on 2005-06-30 for evaporator for a refrigeration device.
This patent application is currently assigned to BSH Bosch und Siemens Hausgerate GmbH. Invention is credited to Howe, Michael, Ihle, Hans, Konopa, Helmut, Maier, Roland, Neumann, Michael.
Application Number | 20050138959 11/017614 |
Document ID | / |
Family ID | 34701938 |
Filed Date | 2005-06-30 |
United States Patent
Application |
20050138959 |
Kind Code |
A1 |
Howe, Michael ; et
al. |
June 30, 2005 |
Evaporator for a refrigeration device
Abstract
The evaporator for a refrigeration device includes a hydrophobic
coating on the surface thereof to inhibit the icing of the
evaporator during operation and to reduce the generation of noises
arising from relative displacements between the evaporator and the
ice attached thereto. The evaporator is a lamellar evaporator and
has a pipeline through which a refrigerant flows and a surface in
thermally conductive contact with the pipeline. The surface is a
heat-exchange surface and has a hydrophobic layer of oil
thereon.
Inventors: |
Howe, Michael; (Giengen,
DE) ; Ihle, Hans; (Giengen, DE) ; Konopa,
Helmut; (Leipheim, DE) ; Maier, Roland;
(Neresheim, DE) ; Neumann, Michael; (Ulm,
DE) |
Correspondence
Address: |
LERNER AND GREENBERG, PA
P O BOX 2480
HOLLYWOOD
FL
33022-2480
US
|
Assignee: |
BSH Bosch und Siemens Hausgerate
GmbH
|
Family ID: |
34701938 |
Appl. No.: |
11/017614 |
Filed: |
December 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11017614 |
Dec 20, 2004 |
|
|
|
PCT/EP03/05864 |
Jun 4, 2003 |
|
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Current U.S.
Class: |
62/515 ;
165/133 |
Current CPC
Class: |
F25B 47/006 20130101;
F25B 39/02 20130101 |
Class at
Publication: |
062/515 ;
165/133 |
International
Class: |
F28F 013/18; F28F
019/02; F25C 001/14; F25B 039/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 2002 |
DE |
102 27 135.6 |
Claims
We claim:
1. An evaporator for a refrigeration device, comprising: a pipeline
through which a refrigerant flows; and a surface thermally
conductively connected to said pipeline, said surface being a
heat-exchange surface and having thereon a hydrophobic layer of
oil.
2. The evaporator according to claim 1, wherein: said pipeline has
a pipeline surface having thereon said hydrophobic layer of oil;
and said heat-exchange surface has thereon said hydrophobic layer
of oil.
3. The evaporator according to claim 1, wherein said pipeline has
an outer surface having thereon said hydrophobic layer of oil.
4. The evaporator according to claim 1, wherein said pipeline and
said surface form a lamellar evaporator.
5. A lamellar evaporator for a refrigeration device, comprising: a
hollow pipe for conveying a refrigerant therethrough; and a
lamellar heat-exchange surface thermally conductively connected to
said pipe surface, said heat-exchange surface being at least
partially coated with a hydrophobic layer of oil.
6. The evaporator according to claim 1, wherein said pipeline has
an outer surface at least partially coated with said hydrophobic
layer of oil.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuing application, under 35 U.S.C. .sctn.
120, of copending international application No. PCT/EP03/05864,
filed Jun. 4, 2003, which designated the United States; this
application also claims the priority, under 35 U.S.C. .sctn. 119,
of German patent application No. 102 27 135.6, filed Jun. 18, 2002;
the prior applications are herewith incorporated by reference in
their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an evaporator for a
refrigeration device. The surface of an evaporator of this type
reaches temperatures of below 0.degree. C. when the evaporator is
supplied with refrigerant. Moisture in the air from the interior of
the refrigeration device may, therefore, condense and freeze on the
surface of the evaporator. This initially results on the surface of
the evaporator in the production of a thin, uniformly distributed
layer of frost that, provided that it is not defrosted in the
meantime, becomes ever thicker over the course of operation of the
refrigeration device and, finally, coalesces to form a solid, hard
layer of ice. Because the temperature of the evaporator varies over
the course of time, depending on whether it is supplied with
refrigerant or not, this layer of ice periodically expands over the
course of time and contracts again. In the process, stresses build
up between the layer of ice and the evaporator situated
therebeneath and, finally, cause the layer of ice to slip backward.
The cracking noises produced as a result are found to be
disturbing.
SUMMARY OF THE INVENTION
[0004] It is accordingly an object of the invention to provide an
evaporator for a refrigeration device that overcomes the
hereinafore-mentioned disadvantages of the heretofore-known devices
of this general type and in which these cracking noises are
reduced.
[0005] With the foregoing and other objects in view, there is
provided, in accordance with the invention, an evaporator for a
refrigeration device, including a pipeline through which a
refrigerant flows and a surface thermally conductively connected to
the pipeline, the surface being a heat-exchange surface and having
thereon a hydrophobic layer of oil.
[0006] According to the invention, the surface of the evaporator,
on which surface ice could form, is provided with a hydrophobic
coating. Such a coating acts to delay the formation of first ice
crystals on an ice-free evaporator and, thus, to extend the time
required for an amount of ice to accumulate on the evaporator
following a defrosting operation, which is thick enough to cause
cracking noises. A further effect of the hydrophobic layer is that
it prevents the formation of a homogeneous layer of frost on the
surface of the evaporator. Instead, icing up begins on a small
number of unavoidable nuclei on the surface of the evaporator. The
beads of ice that form there grow more or less uniformly over the
entire surface and, thus, reach a substantial thickness before they
begin to coalesce. That is to say, in comparison to a
non-hydrophobic evaporator, a large amount of ice can collect on
the evaporator according to the invention before a coherent layer
is produced, which layer is capable of producing cracking
noises.
[0007] With the objects of the invention in view, there is also
provided a lamellar evaporator for a refrigeration device,
including a hollow pipe for conveying a refrigerant therethrough
and a lamellar heat-exchange surface thermally conductively
connected to the pipe surface, the heat-exchange surface being at
least partially coated with a hydrophobic layer of oil.
[0008] In accordance with another feature of the invention, the
pipeline has a pipeline surface having thereon the hydrophobic
layer of oil and the heat-exchange surface has thereon the
hydrophobic layer of oil.
[0009] In accordance with a further feature of the invention, the
pipeline has an outer surface having thereon the hydrophobic layer
of oil.
[0010] In accordance with an added feature of the invention, the
pipeline has an outer surface at least partially coated with the
hydrophobic layer of oil.
[0011] In accordance with an additional feature of the invention,
the pipeline and the surface form a lamellar evaporator.
[0012] A further advantage of the growth of islands of the layer of
ice is that surface regions of the evaporator remain free of ice
for a relatively long time and, thus, make effective heat exchange
possible between the refrigerant and the area surrounding the
evaporator even when a substantial amount of ice has collected on
other regions of the evaporator surface. The time interval between
two defrosting phases can, therefore, be chosen to be longer than
in the case of a non-hydrophobic evaporator. This produces an
increased convenience for the user of a refrigeration device
equipped with an evaporator according to the invention, and a
reduction in the power consumption of the refrigeration device and,
thus, a reduction in its operating costs.
[0013] The hydrophobic coating may contain, preferably, a silicone
as the hydrophobicizing constituent.
[0014] The coating may be applied as a strengthening layer of
lacquer or as a layer of oil. In such a case, the layer of oil has
the particular advantage that, because it is not solid, it promotes
the displaceability of the beads of ice that are forming on the
surface of the evaporator such that, even in the case of complete
icing up of the evaporator with a layer thickness sufficient to
produce cracking noises in the case of a conventional evaporator,
the cracking noises are reduced. This occurs in the case of the
evaporator according to the invention because high thermal stresses
that are discharged as loud cracking noises do not need to be built
up to displace the crust of ice with respect to the evaporator.
Rather, a significantly lower stress is sufficient to allow the
layer of ice to slide relative to the evaporator or possibly even
bring about a continuous sliding movement of the layer of ice on
the evaporator.
[0015] The evaporator according to the invention is configured,
preferably, as a lamellar evaporator suitable for use in a
recirculating air refrigerator or freezer.
[0016] Other features that are considered as characteristic for the
invention are set forth in the appended claims.
[0017] Although the invention is illustrated and described herein
as embodied in an evaporator for a refrigeration device, it is,
nevertheless, not intended to be limited to the details shown
because various modifications and structural changes may be made
therein without departing from the spirit of the invention and
within the scope and range of equivalents of the claims.
[0018] The construction and method of operation of the invention,
however, together with additional objects and advantages thereof,
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0019] The FIGURE is a perspective view of the evaporator according
to the invention.
DESCRIPTION OF THE PREFFERED EMBODIMENTS
[0020] Referring now to the single FIGURE of the drawing, it is
seen that a partially iced-up section of a lamellar evaporator 4
according to the invention. The lamellar evaporator 4 includes a
pipe 1 through which refrigerant flows during operation. A lamella
2 is helically wound around the outer surface of the pipe 1. The
lamella 2 and the outer surface of the pipe 1, on which surface the
lamella 2 is mounted, form the heat-exchange surface of the
lamellar evaporator 4 and are provided with a hydrophobic coating
of silicone oil.
[0021] On account of the hydrophobicity of the coating, a large
amount of energy is required to wet the surface of the lamellar
evaporator 4 and this energy must be released when moisture freezes
on the surface. Such a property constitutes a considerable obstacle
for the new formation of ice crystals on the surface. Therefore, a
considerable proportion of the moisture of a flow of air that flows
past the lamellar evaporator does not even condense on the lamellar
evaporator 4 itself when the flow of air is supersaturated with
moisture, and the reason for this is simply that the moisture does
not strike a surface on which freezing would be energetically
optimum. The lamellar evaporator 4, therefore, only slightly dries
the air in the interior of the refrigeration device when it is used
in a recirculating air or no-frost refrigeration device, this being
extremely vulnerable for the storage of vulnerable food products
such as, for example, fresh vegetables.
[0022] For moisture in the air to condense on the lamellar
evaporator 4, the lamellar evaporator 4 must have surface regions
on which the condensation is energetically optimum. Such locations
are usually condensation nuclei in the form of dust particles,
surface discontinuities, or the like that are unavoidably present
on the surface of the lamellar evaporator 4 but only make up a very
small part of it. During operation of the lamellar evaporator 4, a
large number of compact beads of ice 3 form--as shown in the
figure--on these condensation nuclei. Further moisture from the air
surrounding the lamellar evaporator 4 preferably condenses on the
surface of these beads of ice 3 so that the beads 3 increase in
thickness and diameter over the course of time, while regions of
the surface of the lamellar evaporator 4 that are situated between
the beads remain free of ice for a long time and make efficient
heat exchange possible between refrigerant circulating in the
lamellar evaporator 4 and the surrounding air.
* * * * *