TECHNICAL FIELD
[0001] The present disclosure relates to an article for generating aerosol and a method
of manufacturing the article for generating aerosol.
BACKGROUND ART
[0002] Recently, the demand for alternative methods to overcome the shortcomings of general
cigarettes has increased. For example, there is an increasing demand for a method
of generating aerosol by heating an aerosol-generating material, rather than by burning
cigarettes. Accordingly, research into heating-type cigarettes or heating-type aerosol-generating
devices has been actively conducted.
DESCRIPTION OF EMBODIMENTS
TECHNICAL PROBLEM
[0003] Provided are a segment that transfers heat to a material generating aerosol in an
article generating aerosol and a method of manufacturing the same.
[0004] The technical problems to be solved by the present embodiment are not limited to
the technical problems as described above, and other technical problems may be driven
from the following embodiments.
SOLUTION TO PROBLEM
[0005] According to an aspect of the disclosure, an aerosol-generating article includes:
a heat transfer unit that includes structure particles and a binder, wherein each
of the structure particles contains carbon and the binder adheres to surfaces of the
structure particles and supports the structure particles to form pores between the
structure particles; and a medium unit that includes solid particles and heat transfer
materials, wherein the solid particles generate an aerosol and the heat transfer materials
are mixed with the solid particles and transfer heat to the solid particles.
[0006] In the aerosol-generating article, the medium unit may further include a binder that
adheres to surfaces of the solid particles and supports the solid particles to form
pores between the solid particles.
[0007] In the aerosol-generating article, the binder may include any one of carboxymethyl
cellulose, hydroxypropyl methylcellulose, pullulan, and starch.
[0008] In the aerosol-generating article, the structure particles may include any one of
activated carbon, carbon nanotubes, graphene, a polymer substrate having a thermal
conductivity of 0.1 W/mK or more and a metal material having a thermal conductivity
of 10.0 W/mK or more.
[0009] In the aerosol-generating article, the heat transfer material may include any one
of activated carbon, carbon nanotubes, graphene, a polymer substrate having a thermal
conductivity of 0.1 W/mK or more and a metal material having a thermal conductivity
of 10.0 W/mK or more.
[0010] In the aerosol-generating article, one side of the medium unit may be connected to
the heat transfer unit, the aerosol-generating article may further comprise a mouthpiece
unit connected to the other side of the medium unit, and when heat in a temperature
range of about 250 °C to about 350 °C is applied to an end portion of the heat transfer
unit, a temperature range of a portion where the heat transfer unit and the medium
unit contact each other is about 220 °C to about 320 °C, a temperature range of a
portion where the medium unit and mouthpiece unit contact each other is about 70 °C
to about 100 °C, and a temperature range of an end portion of the mouthpiece unit
is about 40 °C to about 70 °C.
[0011] According to another aspect of the disclosure, a method of manufacturing an aerosol-generating
article includes: forming a heat transfer unit by mixing a binder and structure particles
containing carbon so that the binder adheres to surfaces of the structure particles
and pores are formed between the structure particles; forming a medium unit by mixing
solid particles to generate aerosol and heat transfer material to transfer to the
solid particles; and connecting the heat transfer unit and the medium unit and wrapping
the heat transfer unit and the medium unit with an outer wrapper.
[0012] In the method, the forming of the medium unit may include mixing a binder together
with the solid particles and the heat transfer material so that the binder adheres
to surfaces of the solid particles and pores are formed between the solid particles.
[0013] In the method, a suction resistance of a mixture of the structure particles and the
binder may be 50 mmH
2O/30 mm or less.
ADVANTAGEOUS EFFECTS OF DISCLOSURE
[0014] The point adhesions between the structure particles and the binder may be advantageous
for forming a high porosity in a small volume. In addition, a porosity of the structure
particles may be increased by using a small amount of the binder, and a hardness of
the structure particles may be improved.
[0015] By forming the point adhesions between the binder and particles of the heat transfer
unit and the medium unit, the porosity may be increased, and thus the suction resistance
of the heat transfer unit may be reduced.
BRIEF DESCRIPTION OF DRAWINGS
[0016]
FIG. 1 is a diagram illustrating an article generating aerosol according to some embodiments.
FIG. 2 is a diagram illustrating an aerosol-generating article including a heat transfer
unit according to some embodiments.
FIG. 3 is a diagram for illustrating a process in which pores are formed through point
adhesions between structure particles containing carbon and a binder according to
some embodiments.
FIG. 4 is a graph illustrating temperatures according to locations in an aerosol-generating
article according to some embodiments.
FIG. 5 is a flowchart of a method of manufacturing an aerosol-generating article having
a heat transfer unit according to some embodiments.
BEST MODE
[0017] An aerosol-generating article includes: a heat transfer unit that includes structure
particles and a binder, wherein each of the structure particles contains carbon and
the binder adheres to surfaces of the structure particles and supports the structure
particles to form pores between the structure particles; and a medium unit that includes
solid particles and heat transfer materials, wherein the solid particles generate
an aerosol and the heat transfer materials are mixed with the solid particles and
transfer heat to the solid particles.
MODE OF DISCLOSURE
[0018] With respect to the terms used to describe the various embodiments, general terms
which are currently and widely used are selected in consideration of functions of
structural elements in the various embodiments of the present disclosure. However,
meanings of the terms may be changed according to intention, a judicial precedence,
the appearance of new technology, and the like. In addition, in certain cases, terms
which are not commonly used may be selected. In such a case, the meanings of the terms
will be described in detail at the corresponding portions in the following descriptions.
Therefore, the terms used in the various embodiments should be defined based on the
meanings of the terms and the descriptions provided herein.
[0019] Throughout the specification, when there is a description about a case in which a
part is connected to another part, this includes not only the case of being directly
connected, but also the case of being electrically connected with another element
therebetween. In addition, unless explicitly described to the contrary, the word "comprise"
and variations such as "comprises" or "comprising" will be understood to imply the
inclusion of stated elements but not the exclusion of any other elements.
[0020] Hereinafter, the present disclosure will now be described more fully with reference
to the accompanying drawings, in which exemplary embodiments of the present disclosure
are shown such that one of ordinary skill in the art may easily work the present disclosure.
The disclosure may, however, be embodied in many different forms and should not be
construed as being limited to the embodiments set forth herein.
[0021] In the embodiments, an "aerosol-generating material" may mean a material capable
of generating aerosol and may also mean an aerosol-forming substrate. The aerosol
may include volatile compounds. The aerosol-generating material may be solid or liquid.
[0022] For example, the solid aerosol-generating material may include a solid material based
on tobacco raw materials such as a tobacco sheet, shredded tobacco, reconstituted
tobacco, and the liquid aerosol-generating material may include a liquid material
based on nicotine, tobacco extract and various flavoring agents. The disclosure is
not limited to the above example.
[0023] In the present embodiments, the "aerosol-generating device" may be a device that
generates an aerosol using an aerosol-generating material in order to generate an
aerosol that is directly in-halable into a user's lungs through the user's mouth.
For example, the aerosol-generating device may be a holder that is holdable by a user.
[0024] Hereinafter, the embodiments will now be described in detail with reference to the
accompanying drawings.
[0025] FIG. 1 is a diagram illustrating an article generating aerosol according to some
embodiments.
[0026] Referring to FIG. 1, an aerosol-generating article 100 may include an aerosol-generating
material 110, an intermediate structure 120, a cooling structure 130, a filter segment
140, and a wrapper 150.
[0027] The aerosol-generating material 110 may include at least one of glycerin, propylene
glycol, ethylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol,
tetraethylene glycol, and oleyl alcohol.
[0028] The aerosol-generating material 110 may have an elongated rod shape, and the length
of the aerosol-generating material 110 may vary. For example, the length of the aerosol-generating
material 110 may be 7 mm to 15 mm, but the disclosure is not limited thereto. In some
examples, the length of the aerosol-generating material 110 may be about 12 mm. In
addition, the diameter of the aerosol-generating material 100 may be about 7 mm to
about 9 mm, but the disclosure is not limited thereto. In some examples, the diameter
of the aerosol-generating material 110 may be about 7.9 mm.
[0029] Optionally, the aerosol-generating material 110 may contain other additive material
such as a flavoring agent, a wetting agent and/or acetate compounds. For example,
the flavoring agent may include licorice, sucrose, fructose syrup, isosweet, cocoa,
lavender, cinnamon, cardamom, celery, fenugreek, cascarilla, sandalwood, bergamot,
geranium, honey essence, rose oil, vanilla, lemon oil, orange oil, mint oil, caraway,
cognac, jasmine, chamomile, menthol, cassia bark, ylang ylang, salvia, spearmint,
ginger, coriander, coffee, or the like. In addition, the wetting agent may include
glycerin, propylene glycol, or the like.
[0030] For example, a tobacco raw material may be pulverized and then mixed with a solvent
and various additives to be manufactured slurry, and then the slurry may be dried
to form a sheet. After forming the sheet, a plurality of tobacco material strands
may be formed by processing the sheet.
[0031] For example, the aerosol-generating material 110 may include the plurality of tobacco
material strands, and each of the plurality of tobacco material strands may have a
length of about 10 mm to about 14 mm, for example, 12 mm, a width of about 0.8 mm
to about 1.2 mm, for example, 1 mm, and a thickness of about 0.08 mm to about 0.12
mm, for example, 0.1 mm. However, the length, the width, and the thickness of each
of the plurality of tobacco material strands are not limited to the above examples.
[0032] As the aerosol-generating material 110 includes a plurality of strand materials formed
by processing a wide tobacco sheet, a density of a tobacco materials filled in the
aerosol-generating material 110 may be increased. Accordingly, the amount of the aerosol
generated from the aerosol-generating material 110 may be increased, and manufacturing
characteristics of the aerosol-generating material 110 may be improved.
[0033] The filter segment 140 may be arranged side by side with the aerosol-generating material
110, and the aerosol material generated from the aerosol-generating material 110 passes
through the filter segment 140 immediately before being inhaled by the user.
[0034] The filter segment 140 may be formed of various materials. For example, the filter
segment 140 may include cellulose acetate. The filter segment 140 may be made as a
cylindrical filter, a tubular filter including a hollow, or a recessed filter, but
the disclosure is not limited thereto. For example, the length of the filter segment
140 may be about 5 mm to about 15 mm, but the disclosure is not limited thereto.
[0035] Also, the filter segment 140 may include at least one capsule (not shown). The capsule
included in the filter segment 140 may have a configuration in which a content liquid
containing a flavoring material is wrapped with a film. For example, the capsule has
a spherical or cylindrical shape.
[0036] In addition, a material for forming the film of the capsule included in the filter
segment 140 may be starch and/or a gelling agent. For example, a gelling gum or gelatin
may be used as the gelling agent. Also, a gelling aid may be further used as the material
for forming the film of the capsule. For example, calcium chloride may be used as
the gelling aid. Also, a plasticizer may be further used as the material for forming
the film of the capsule. Glycerin and/or sorbitol may be used as the plasticizer.
Also, a coloring agent may be further used as the material for forming the film of
the capsule.
[0037] For example, menthol, plant essential oil, and the like may be used as the flavoring
material contained in the content liquid of the capsule. In addition, as the solvent
of the flavoring material contained in the content liquid, for example, a medium chain
fatty acid triglyceride (MCT) may be used. In addition, the content liquid may contain
other additives such as a pigment, an emulsifier, and a thickener.
[0038] The intermediate structure 120 is arranged between the filter segment 140 and the
aerosol-generating material 110. For example, the intermediate structure 120 may be
arranged adjacent to the aerosol-generating material 110. The intermediate structure
120 may be formed from various materials. For example, the intermediate structure
120 may include cellulose acetate. In addition, the intermediate structure 120 may
be in the form of a tube including a hollow therein, but the disclosure is not limited
thereto.
[0039] A length of the intermediate structure 120 is about 7 mm to about 15 mm, and selectively,
may be about 7 mm. In addition, the length of the intermediate structure 120 may be
variously set, and the entire length of the aerosol-generating material 110 may be
changed according to the length of the intermediate structure 120.
[0040] The cooling structure 130 is arranged between the aerosol-generating material 110
and the filter segment 140, and in particular, may be arranged between the intermediate
structure 120 and the filter segment 140. For example, the cooling structure 130 may
be in contact with the intermediate structure 120 and the filter segment 140.
[0041] The cooling structure 130 may cool the aerosol generated from the aerosol-generating
material 110. For example, when the aerosol-generating article 100 is inserted into
the aerosol-generating device and used by a user, the aerosol generated from the aerosol-generating
material 110 that is heated by the heater may be cooled. Accordingly, the user may
inhale the aerosol at a suitable and safe temperature that is not too high.
[0042] A length of the cooling structure 130 may be about 10 mm to about 20 mm, and selectively,
14 mm, but the disclosure is not limited thereto.
[0043] The cooling structure 130 may be formed of various materials, and for example, may
contain poly lactic acid (PLA).
[0044] The cooling structure 130 may be manufactured in various ways, for example, may be
manufactured, e.g., woven, using fibers containing polylactic acid. In this case,
the risk that the cooling structure 130 is deformed or loses functions by an external
impact may be lowered. In addition, the cooling structure 130 having various shapes
may be manufactured as the method of combining the fibers is changed.
[0045] Also, when the cooling structure 130 is manufactured using fibers, an area of a surface
in contact with the aerosol may be increased. Therefore, an aerosol cooling effect
by the cooling structure 130 may be further improved.
[0046] The wrapper 150 may be formed to wrap the aerosol-generating material 110, the intermediate
structure 130, and the filter segment 140, which are described above. The wrapper
150 may include a plurality of separate wrappers. For example, each of the plurality
of separate wrappers may be formed to wrap the aerosol-generating material 110, the
intermediate structure 130, and the filter segment 140, which are described above.
However, the above described wrapper is only an example, and the embodiment is not
limited thereto. The wrapper 150 may be manufactured as a paper wrapper having oil
resistance or a general paper-type wrapper.
[0047] FIG. 2 is a diagram illustrating an aerosol-generating article including a heat transfer
unit according to some embodiments.
[0048] Referring to FIG. 2, an aerosol-generating article 200 may include a heat transfer
unit 210, a medium unit 220, a mouthpiece unit 230, and a wrapper 240. One side of
the medium unit 220 may be connected to the heat transfer unit 210, and the other
side of the medium unit 220 may be connected to the mouthpiece unit 230.
[0049] The heat transfer unit 210 may receive heat from an external heating device and transfer
heat to the medium unit 220. The heat transfer unit 210 may include a binder, and
structure particles containing carbon. The structure particles and the binder may
form point adhesions, and the binder may adhere to surfaces of the structure particles
to support bonding between the structure particles.
[0050] By the point adhesions between the structure particles and the binder, pores may
be formed between the structure particles. More pores may be formed between the structure
particles by an adhesion in which the binder is in contact with the structure particles
in the form of a point than by an adhesion in which the binder is in contact with
the structure particles in the form of a line. When the point adhesions between the
structure particles and the binder are conducted according to an embodiment, the porosity
of the heat transfer unit 210 may be increased. When the porosity is increased, suction
resistance of the heat transfer unit 210 may be reduced.
[0051] The medium unit 220 may include solid particles and a heat transfer material. The
solid particles may include volatile compounds. The volatile compounds may be released
from the solid particles when the volatile compounds are heated, and may generate
aerosol. The heat transfer material may be mixed between the solid particles to transfer
heat received from the heat transfer unit 210 to the solid particles.
[0052] For example, heat transfer between the solid particles may be performed. The heat
transfer material may improve the heat transfer efficiency of the medium unit 220.
[0053] The mouthpiece unit 230 may include a region through which aerosol generated from
the mouthpiece unit 220 passes immediately before the aerosol is inhaled by the user.
The mouthpiece unit 230 may be formed of various materials. For example, the mouthpiece
unit 230 may include cellulose acetate. Also, the mouthpiece unit 230 may be made
as a recessed filter including a hollow, but the disclosure is not limited thereto.
[0054] The wrapper 240 may be formed to wrap the heat transfer unit 210, the medium unit
220, and the mouthpiece unit 230, which are described above. The wrapper 240 may include
a plurality of separate wrappers. For example, each of the plurality of separate wrappers
may be formed to wrap the heat transfer unit 210, the medium unit 220, and the mouthpiece
unit 230 described above, respectively. However, the above described wrapper is only
an example, and the embodiment is not limited thereto. The wrapper 240 may be manufactured
as a paper wrapper having oil resistance or a general paper-type wrapper.
[0055] Referring to FIGS. 1 and 2, the aerosol-generating article 200 shown in FIG. 2 does
not include a cooling structure, unlike the aerosol-generating article 100 shown in
FIG. 1. The aerosol-generating article 200 shown in FIG. 2 includes a heat transfer
unit 210, and in the aerosol-generating article 200, heat is transferred to the medium
unit 220 by the heat transfer unit 210 to control temperature, and thus, a separate
cooling structure may not be required.
[0056] FIG. 3 is a diagram for illustrating a process in which pores are formed through
point adhesions between structure particles containing carbon and a binder according
to some embodiments.
[0057] Referring to FIG. 3, an aerosol-generating structure may include structure particles
300 including a carbon component 330 and a binder 310. The carbon component 330 may
include a material that is released from the structure particles 300 and forms aerosol
when the material is heated.
[0058] For example, the structure particles 300 may be strand-type reconstituted tobacco
particles. Alternatively, a plurality of structure particles 300 may include a reconstituted
tobacco material, such as a rod, that includes pieces. The reconstituted tobacco material
may be formed by processing a tobacco sheet that is manufactured by a method in which
a tobacco raw material is pulverized and mixed with a solvent and various additives
to be manufactured slurry, and then the slurry is dried to form the tobacco sheet.
[0059] According to some embodiments, by a binder 310 point adhered to the surfaces of the
structure particles 300, pores 320 may be formed between the structure particles 300.
[0060] The porosity formed for the binder 310 of the same part by weight may vary according
to various types of the structure particles 300. For example, the structure particles
300 of FIG. 3 that are strand type reconstituted tobacco materials may have higher
porosity than the solid particles 200 of FIG. 2 that are granular type reconstituted
tobacco materials.
[0061] On the basis of 100 parts by weight of the structure particles 300, it may be desirable
to form a point adhesion at a ratio in which the binder 310 has about 10 parts by
weight to about 35 parts by weight.
[0062] When the part by weight of the binder 310 with respect to 100 parts by weight of
the structure particles 300 is 35 parts by weight or more, even if the amount of the
binder 310 is increased, adhesion may hardly be improved. Also, when the part by weight
of the binder 310 with respect to 100 parts by weight of the structure particles 300
is 35 parts by weight or more, the total volume of aerosol-generating structure may
be increased by the binder 310, and the proportion of the pores may be reduced. Accordingly,
the suction resistance of the aerosol-generating structure may be increased In addition,
because the surfaces of the structure particles 300 is covered with the binder 310,
rate of adsorption between the binder 310 and the structure particles 300 may be rapidly
reduced.
[0063] On the other hand, when the part by weight of the binder 310 is 10 parts by weight
or less with respect to 100 parts by weight of the structure particles 300, the strength
of adhesion between the structure particles 300 and the binder 310 decreases, and
the structure particles 300 and the binder 310 may not be properly attached.
[0064] The point adhesions between the structure particles 300 and the binder 310 may provide
an advantage of forming a high porosity in a small volume. In addition, a porosity
of the structure particles 300 may be increased by using a small amount of the binder
310, and a hardness of the structure particles 300 may be improved.
[0065] For example, when a proportion of the binder 310 and the structure particles 300
is maintained at a ratio such that the binder 310 has 10 parts by weight to 35 parts
by weight based on 100 parts by weight of the structure particles 300, the suction
resistance of the aerosol-generating structure may be 50 mmH
2O/30 mm or less. In addition, by forming the point adhesion between the binder 310
and the solid particles, the hardness of the aerosol-generating structure may be improved
by 90 % or more.
[0066] The binder may include at least one of carboxymethyl cellulose, hydroxypropyl methylcellulose,
pullulan, and starch.
[0067] In addition, although not shown in the drawings, the pores 320 between the structure
particles 300 may include a heat transfer material.
[0068] When the aerosol-generating structure is heated, the heat transfer material may transfer
heat to the solid particles, and therefore, the heat transfer efficiency of the aerosol-generating
structure may be increased. For example, heat transfer efficiency of the aerosol-generating
structure including the heat transfer material may be increased by 2 %, compared to
an aerosol-generating structure not including a heat transfer material.
[0069] The heat transfer material may include at least one of activated carbon, carbon nanotubes,
graphene, and a polymer substrate having a thermal conductivity of 0.1 W/mK or more.
Also, the heat transfer material may include any one of metal materials having the
thermal conductivity of 10.0 W/mK or more, such as iron, nickel, aluminum, copper,
and stainless steel.
[0070] FIG. 4 is a graph illustrating temperatures according to locations in an aerosol-generating
article according to some embodiments.
[0071] Referring to FIG. 4, the position in the aerosol-generating article may include an
end portion of the heat transfer unit, one side, which is in contact with the heat
transfer unit, of the medium unit, the other side, which is in contact with the mouthpiece
unit, of the medium unit, and an end portion of the mouthpiece portion.
[0072] An end portion of a heat transfer unit receiving heat from the external heating device
may be heated to about 250 °C to about 350 °C. As heat is transferred from the heat
transfer unit to the medium unit, one side, which is in contact with the heat transfer
unit, of a medium unit may have a temperature range of about 220 °C to about 320 °C.
When the user puffs on the aerosol-generating article, heat is transferred in a direction
from the medium unit toward the mouthpiece unit, and the farther from the heat transfer
unit and the closer to the mouthpiece unit, the lower the temperature. Accordingly,
the other side, which is in contact with the mouthpiece unit, of the medium unit may
have a temperature range of about 70 °C to about 100 °C. In addition, in the mouthpiece
unit, the closer to an end, the lower the temperature. Accordingly, the end of the
mouthpiece unit may have a temperature range of about 40 °C to about 70 °C.
[0073] Because the heat transfer unit includes a carbon component, the heat transfer may
be quickly heated to a high temperature by the external heating device. The temperature
of heat generated from the heated heat transfer unit may be reduced as the heat is
transferred thorough the aerosol-generating article, and when the heat is transferred
to mouthpiece unit, the temperature in the mouthpiece unit may be reduced to a temperature
suitable for puffing on the mouthpiece unit by the user.
[0074] The aerosol-generating article including the heat transfer unit to which heat is
transferred from the external heating device may not require a cooling structure.
[0075] FIG. 5 is a flowchart of a method of manufacturing an aerosol-generating article
having a heat transfer unit according to some embodiments. A method of manufacturing
an aerosol-generating article may be performed by an apparatus for manufacturing an
aerosol-generating article. Those skilled in the art will appreciate that the apparatus
for manufacturing an aerosol-generating article may be an apparatus that is generally
used in the art to make an aerosol-generating article.
[0076] Referring to FIG. 5, in operation S500, an apparatus for manufacturing an aerosol-generating
article may form a heat transfer unit by mixing a binder and structure particles.
[0077] When the apparatus for manufacturing an aerosol-generating article mixes the structure
particles and a first binder, pores may be formed between the structure particles
as the first binder is point adhered to surfaces of the structure particles. Because
the structure included in the heat transfer unit includes a carbon component, the
structure particles may be quickly heated to a high temperature in a short time. In
addition, by a point adhesion between the first binder and the structure particles,
porosity between the structure particles may be increased, and accordingly, the suction
resistance of the heat transfer unit may be decreased.
[0078] In operation S510, the apparatus for manufacturing the aerosol-generating article
may form a medium unit by mixing a solid particles and a heat transfer material. The
medium unit may further include a second binder that adheres to surfaces of the solid
particles and supports the solid particles to form pores between the solid particles.
Because the second binder supports the solid particles, a relative position between
the solid particles or a proportion of pores formed between the solid particles may
be maintained.
[0079] In operation S520, the apparatus for manufacturing the aerosol-generating article
may connect the heat transfer unit, the medium unit and the mouthpiece unit and wrap
the heat transfer unit, the medium unit and the mouthpiece unit with an outer wrapper.
[0080] The apparatus for manufacturing the aerosol-generating article may produce a mouthpiece
unit. The mouthpiece unit may include a region through which aerosol generated from
the mouthpiece unit passes immediately before the aerosol is inhaled by the user.
The mouthpiece unit may be produced by any suitable method that may be selected by
one skilled in the art.
[0081] The apparatus for manufacturing the aerosol-generating article may manufacture an
aerosol-generating article by connecting one side of the medium unit to heat transfer
unit, connecting the other side of the medium unit to the mouthpiece unit, and wrapping
the connecting structure with an outer wrapper.
[0082] The aerosol-generating article including the heat transfer unit according to the
present disclosure may not include a separate cooling structure. In addition by forming
the point adhesions between the binder and particles of the heat transfer unit and
the medium unit, the porosity may be increased, and thus the suction resistance of
the heat transfer unit may be reduced.
[0083] Those of ordinary skill in the art related to the present embodiments may understand
that various changes in form and details may be made therein without departing from
the scope of the characteristics described above. The disclosed methods should be
considered in a descriptive sense only and not for purposes of limitation. The scope
of the present disclosure is disclosed in the appended claims rather than disclosed
in the above description, and all differences within the scope of equivalents thereof
should be construed as being included in the present disclosure.