Patent Application
20240288234
This application claims priority to European Patent Application No. 23461525.0 filed Feb. 28, 2023, the entire contents of which is incorporated herein by reference.
The present disclosure is concerned with the turnaround section in a heat exchanger.
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.
One type of AM heat exchanger design has a so-called weave core in which wavy channels are formed for the hot and cold fluid and the hot and cold fluid channels are interwoven in a continuous manner. Such designs are typically cross-flow designs where the hot fluid flows through wavy channels in one direction and the cold fluid flows through wavy channels interlaced through the hot flow channels in a direction transverse to the one direction. The integrated geometry of the weave makes such heat exchangers most suitable for single pass designs—i.e. where the hot and cold fluid enters their respective channels at one end on one side/end of the core and exits at the opposite end.
In some cases, it is preferable to use a two-pass design—i.e. for each layer of the core, the fluid flows along a respective channel in one direction and is then turned around at a turnaround section of the core and flows back along a channel in the opposite direction, the fluid thus making two passes of the core. The turnaround section is typically provided by a so-called turnaround tank fitted to the end of the heat exchanger core, into which fluid flows from all of the channels and layers from the first pass section of the core. The turnaround section is shaped and may be provided with vanes or the like to ensure that the fluid follows the path required to change direction. The turnaround tank is commonly a tank defining a void, positioned at the end of the core, into which fluid flows from the first pass through the core and where the fluid direction is changed due to the velocity of the fluid flow as it flows through the tank to flow back through the second pass section of the core. Whilst such heat exchanger designs are useful for some heat exchange designs, no heat exchange occurs in the turnaround section. Further, the fluid distribution in the main core section can be disturbed due to the turnaround section design. Another issue with using a conventional turnaround tank design with such AM weave core heat exchanger designs is that the large voids required in such a turnaround tank to receive all of the fluid from all channels in a layer is difficult to manufacture using 3D printing/AM methods. There is a desire to provide an improved turnaround section design which can be easily formed using AM, which reduces waste of the heat energy in the fluid in that section and which mitigates the problems of disturbance and so improves the performance of the heat exchanger.
According to the disclosure, there is provided a turnaround section for use with a two-pass crossflow heat exchanger, the turnaround section comprising an arcuate housing and a plurality of arcuate fluid flow channels radially spaced within the housing, each arcuate channel having a first end configured, in use, to receive a first fluid from flow channels of a heat exchanger core and a second end to return the first fluid to return channels of the core, and wherein a plurality of separators are provided between each adjacent pair of arcuate channels to form further channels between the arcuate channels that extend and provide for flow of a second fluid in a plane transverse to the plane of the arcuate channels.
Examples according to the disclosure will now be described with reference to the drawings. It should be noted that these are examples only and that variations are possible within the scope of the claims.
The turnaround section of a two-pass cross-flow type heat exchanger will first be described with reference to
If the turnaround section were a conventional turnaround tank or large void, the hot fluid from all of the channels in all of the layers would meet and mix in that area and would be guided due to velocity and the shape of the arcuate turnaround section back to the return channels. In particular, for those return channels closer to the centre of the layer, the fluid in the turnaround section will be unlikely to be turned so much that it is able to enter them. As mentioned above, however, this is thermally inefficient and can be disruptive to the flow in the main core section, as well as being difficult to manufacture using AM.
The turnaround section 20 of this disclosure, therefore, has an arcuate housing 200 is formed as a number of arcuate channels 30 each coinciding at one end 32 with one or more of the first channels 10 and at an opposite end 34 with a corresponding return channel 10′. In other words, the channels 30 in the turnaround section are formed such that one or more of the first channels 10 feeds into each turnaround channel and the fluid flowing through that turnaround channel flows directly into a corresponding one or more of the return channels 10′. In the example shown, pairs of adjacent first channels meet at the end 2 of the layer and feed into a common turnaround channel 32 which then, in turn, at its opposite end 34, feeds into the ends of two adjacent return channels. It is feasible that the channels 10, 10′ of the main core section are formed differently from the design shown in
To ensure the required structural strength and retain the proper positioning and structure of the turnaround channels 30, as well as to provide a secondary heat transfer surface, separators e.g. fins 40 are formed between adjacent turnaround channels 30. The number and dimensions of the turnaround channels and the separators can be varied according to the heat exchanger design.
The heat exchange properties of this design may be further enhanced by using the spaces between the arcuate turnaround channels and between the separators as channels 25 through which the transverse cold air is flowed in the same way as in the main core section. The turnaround section then participates in the heat exchange function which improves efficiency and performance of the heat exchanger.
As mentioned above, the cold flow channels in the main core section provide turbulent flow if the hot channels are wavy, which improves the thermal efficiency of the heat exchanger. This advantage can also be obtained in the turnaround section if the separators and/or the turnaround channels have a wavy shape.
The design of the turnaround section with its channels and separators lends itself to being formed easily by additive manufacture and so the core and turnaround can be integrally formed by AM. This allows the heat exchanger to be manufactured quickly, easily and inexpensively compared to conventional heat exchangers.
This can be explained with reference to
The channels in the turnaround section provide for an improved distribution of the fluid in that section, enabling the fluid to flow more uniformly distributed into all return channels 10′ and also allows the turnaround section to participate in the heat exchange process. The section can also be easily integrally formed with an AM manufactured main core section. This also allows for an overall reduction in size, weight and cost of the heat exchanger.
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 |
|---|---|---|---|
| 23461525.0 | Feb 2023 | EP | regional |
