This application claims priority to European Patent Application No. 22461580.7 filed Jul. 13, 2022, the entire contents of which is incorporated herein by reference.
The present disclosure is concerned with channels for the flow of fluid in a heat exchanger, and specifically channels made by additive manufacturing.
Heat exchangers typically work by the transfer of heat between fluid flowing in parallel channels defined by metal plates of a heat exchanger core. A heat exchanger core is generally in the form of a block made up of layers of plates which define the channels through which the fluid flows. The channels are arranged such that hot fluid flows through some channels and cold fluid flows through other channels with the hot and cold channels arranged either vertically or horizontally adjacent each other such that heat is exchanged across the boundary between the channels. Thermal properties are improved by the introduction of turbulence in the flow channels and so, conventionally, a heat exchanger core comprises corrugated metal plates arranged adjacent each other so as to define corrugated flow channels for the heat exchange fluids.
Additive manufacture, or 3D printing, has recently become a preferred manufacturing method for many parts and components due to the fact that it is relatively quick and low cost and allows for great flexibility in the design of new components and parts. Due to the fact that components and parts made by additive manufacture (AM) can be quickly made in a custom designed form, as required, AM also brings benefits in that stocks of components do not need to be manufactured and stored to be available as needed. AM parts can be made of relatively light, but strong materials. As AM is becoming more popular in many industries, there is interest in manufacturing heat exchangers using AM.
In conventional heat exchanger channels, the viscous fluids that are commonly used create a thick boundary layer at the walls of the channels. This boundary layer presents a resistance to heat exchange across the channel walls and reduces the amount of energy that can be transferred through the channel wall by heat exchange. Additive manufacturing provides the opportunity to create new shapes of heat exchanger channel to address this problem.
According to this disclosure there is provided a channel for a heat exchanger, through which heat exchange fluid flow will flow, in use, the channel comprising an elongate tubular channel body extending along an axis A from a first end to a second end, the channel body having walls, the interior surface of which define an interior channel through which heat exchanger fluid flows from the first end to the second end, and wherein the channel body comprises two or more straight sections having a constant cross section in which the interior channel has a rectangular, square or triangular cross-section, and a twisted section between the or each pair of adjacent straight sections, in the axial direction, the twisted section being a section resulting from one of the straight sections twisted about the axis A with respect to an adjacent straight section, wherein at the twisted section the interior channel has a cross-section different from the cross section at the adjacent straight section, thus creating a swirl effect on fluid flowing through the interior channel.
Also provided is a heat exchanger, and a method of manufacturing a channel for a heat exchanger.
Examples of heat exchanger channels and methods of making them, according to the disclosure, will be described with reference to the drawings. It should be noted that variations are possible within the scope of the claims.
Typically, a heat exchanger comprises a plurality of fluid flow channels defined between layers of metal plates and through which heat exchange fluids flow. The fluids are provided to the core of plates and channels via a manifold such that a relatively cold fluid flows through some of the channels and a relatively hot fluid flows through others of the channels. The channels are arranged such that their outer walls are in contact with outer walls of other channels such that heat exchange takes place across the adjacent channel walls due to the different temperature of the fluids flowing through the channels. As mentioned above, conventionally, the channels have been formed by corrugated sheets with the corrugations forming the channels. With the advent of additive manufacturing techniques, however, it has become possible to form channels of different shapes and/or as discrete tubular elements that are assembled side-by-side to form the heat exchanger core. Tubular channels may be, for example, in the form of a rectangular cross-section tube or a triangular cross-section tube.
It is known that the convective heat transfer coefficient can be improved by introducing turbulence in the flow through the channel. In particular, creating turbulence avoids creation of the insulating boundary layer at the channel walls, as mentioned above. Again, the increasing use of additive manufacturing has made it possible to create channels having features that increase turbulence in the flow.
Additive manufacturing of channels does, however, bring its own limitations in that there is a limitation of channel size due to the required post-printing powder removal. It is often desired to create designs with features inside the channels but which have limited impact on the cross-sectional area of the channel to avoid the accumulation of powder, and it is not easy to incorporate additional devices for causing swirl of the fluid as it travels through the channel into the interior of the channel within such constraints.
The channel according to this disclosure is formed using additive manufacture and so is limited in size, but is structured to provide a swirl effect that does not reduce the cross-sectional area of the channel, or only reduces the cross section by a limited amount and so does not hinder powder removal or flow of fluid, but does increase turbulence of the fluid flowing through the channel.
The channel according to this disclosure, an example of which is shown in various views in
In practice, the channel will be formed with several twist sections 30, each adding a further 90/180/60 degree twist of the channel body. After each twist, then, the cross-section of the straight section 20 is aligned with that of the previous straight section, before the twist.
The twists between straight sections thus cause an interruption in the straight channel for the fluid flowing through the channel.
The fact that the swirl effect is formed by the channel body—i.e. in the wall of the channel, also means that this effect is actually created at the location where the boundary layer effect is a particular problem.
The channel is made, as mentioned above, by additive manufacturing or 3D printing. This means that the positions of the twist sections and, hence, the lengths, L1, of the straight section, can be varied as desired, e.g. depending on the flow conditions, temperature, pressure, fluids etc. for the heat exchanger for which the channel is made. The length L2 of the twist section (essentially the pitch of the run) can also be varied as desired. The lengths can be varied to vary the intensity of the swirl effect.
The swirl effect of the twists can be seen in
As seen, for example, in
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.
Number | Date | Country | Kind |
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22461580.7 | Jul 2022 | EP | regional |