CN115523784A - Method and Application of Using Structural Roughness to Enhance Microchannel Heat Transfer Performance - Google Patents

Abstract

The invention discloses a method for strengthening heat transfer performance of a microchannel by utilizing structured roughness and application thereof, which belong to the technical field of strengthened heat transfer. The normal direction of the rough wall surface is vertical to the flowing direction of the fluid in the micro-channel; the peaks of the upper and lower rough surfaces may be aligned or offset. The combination of channels with triangular and sinusoidal surface roughness is higher than rectangular surface roughness when considering the same channel height, width and surface roughness height, spacing. For the three rough microchannels, when the Reynolds number is 100-400, the parameter ranges of the recommended channel height, the rough unit height and the channel contraction flow diameter (the equivalent diameter calculated after 2 times of the rough unit height is subtracted from the channel root height) are 150-400 mu m, 15-45 mu m and 179-663 mu m respectively.

Description

Method and Application of Using Structural Roughness to Enhance Microchannel Heat Transfer Performance

technical field

The invention belongs to the field of passive enhanced heat transfer, and in particular relates to a method and application for enhancing the heat transfer performance of a microchannel by using structured roughness, including micro-electromechanical devices, fuel cells, solar cells, heat exchangers, and the like.

Background technique

Thermal management plays an important role in many engineering applications, especially in the design of microelectronic devices. The advancement of electronic technology has put forward higher requirements for the power density of electronic devices. Therefore, heat transfer at the microscopic level brings great demands and opportunities for the research and development of thermal management systems. In addition, with the development of the modern microelectronics industry, the packaging density is getting higher and higher, and the heat dissipation capability is required to be stronger and stronger. In the past, smooth microchannels with equal cross-sections have been extensively studied due to the limitations of fabrication processes. However, novel heat-transfer-enhancing structures (microfins, grooves, and different channel shapes) are increasingly being used to improve flow mixing in laminar flow, thus enabling microchannels with smaller hydraulic diameters to be optimized in laminar flow. Enhanced heat transfer. However, these innovative configurations also result in higher pressure drops despite improved heat transfer. Therefore, it is necessary to design such microchannel structures to improve the overall heat transfer performance with limited channel size.

Contents of the invention

According to the concept of destroying and disturbing the boundary layer, the object of the present invention is to provide a method and application for enhancing the heat transfer performance of a microchannel by using structured roughness.

On the one hand, the method of utilizing structured roughness to strengthen the heat transfer performance of microchannels is characterized in that the inner walls of the microchannels are designed as rough surfaces with different shapes, which are arranged along the length of the rectangular channel, and the normal direction of the rough walls is in line with the inner surface of the microchannel. The direction of fluid flow is vertical.

Preferably, the rough unit shape may be, but not limited to, triangular, rectangular, or sinusoidal.

Preferably, the sides of the microchannel are smooth walls.

Preferably, the microchannel wall thermal boundary condition is constant heat flow.

Preferably, the peaks on the upper and lower rough surfaces of the microchannel can be aligned or offset.

Preferably, for the three rough microchannels, when the Reynolds number is 100-400, the parameter ranges of channel height, rough unit height and channel constricted flow diameter are 150µm-400µm, 15µm-45µm and 179µm-663µm, respectively.

Preferably, the fabrication material may be, but not limited to, low-alloy steel, stainless steel, copper, copper-nickel alloy and other metals with certain plasticity.

Preferably, the structured rough microchannel can be made, but not limited to, by ordinary metal rectangular microchannel rolling, punching, inlaying or pasting.

The beneficial effects of the present invention are:

=50时的总性能提高了7%，而在

=250时，正弦表面粗糙度的总性能提高了28%。两种不同粗糙度模型（三角形和正弦形）的微通道在雷诺数50

250范围内的性能差异不超过10%。The method of using structured roughness in the present invention to enhance the heat transfer performance of microchannels strongly disturbs the flow. When the fluid flows through the rough surface, due to the existence of triangular, rectangular or sinusoidal wave peaks, the flow state of the fluid is periodic along the flow path. Changes, the flow speed is large and small, so as to enhance the heat transfer. Although the rough surface will increase the flow resistance to a certain extent, after the optimized design, the flow resistance will not rise sharply, and the increase in the calculated resistance coefficient is small. Especially for sine-wave rough microchannels, the increase in resistance coefficient is not obvious due to the smooth transition of the flow channel. It has a good comprehensive performance coefficient, as shown in Figure 3. A channel with a triangular surface roughness is more favorable than a smooth channel at

= 50 overall performance increased by 7%, while at

=250, the overall performance of sinusoidal surface roughness is improved by 28%. Microchannels with two different roughness models (triangular and sinusoidal) at Reynolds number 50

The performance difference in the 250 range is not more than 10%.

Description of drawings

Accompanying drawing 1 is the axonometric schematic diagram of Embodiment 1 of the method for enhancing the heat transfer performance of microchannels by using structured roughness, (a) is a triangle, (b) is a rectangle, and (c) is a sinusoidal waveform;

Accompanying drawing 2 is the schematic cross-sectional diagram of rough microchannels with different cross-sectional shapes, (a) is a triangle, (b) is a rectangle, and (c) is a sinusoidal waveform.

Accompanying drawing 3 is the effect diagram of the comprehensive performance coefficient of rough microchannels with different cross-sectional shapes.

detailed description

The invention proposes a method and application for enhancing heat transfer through structured rough microchannels, which have good effect of enhancing heat transfer, small flow resistance loss, and simple processing and manufacturing. It can be made of copper, stainless steel and other materials through rolling and molding. The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be emphasized that the following description is only exemplary and not intended to limit the scope of the invention and its application.

Example 1

The method for enhancing the heat transfer performance of microchannels by using structured roughness is shown in accompanying drawings 1 and 2. The length L of the three structured rough microchannels is 12 mm, the width W is 12.7 mm, the roughness element width ω is 100 µm, the height r is 30 µm, the pitch s is 250 µm and the shrinkage channel height Hc is 190 µm. The three textured rough surfaces are arranged in an aligned manner. The three structured rough microchannels have a Reynolds number ranging from 50 to 250, and the highest comprehensive coefficient of performance can reach 1.35.

Claims (8)

1. The method for strengthening the heat transfer performance of the microchannel by using the structured roughness is characterized in that the inner wall surface of the microchannel is designed into rough surfaces with different shapes, and the normal direction of the rough wall surface is vertical to the flowing direction of fluid in the microchannel.

2. The method of claim 1 wherein the microchannel asperity surface shapes are selected from the group consisting of but not limited to triangular, rectangular and sinusoidal.

3. The method of claim 1 wherein the microchannel is smooth walled on the sides.

4. The use of the method of claim 1 wherein the microchannel wall thermal boundary condition is constant heat flux.

5. The use of the method of claim 1 wherein the peaks of the upper and lower roughened surfaces of the microchannel are aligned or offset.

6. The application of the method for strengthening the heat transfer performance of the micro-channel by using the structured roughness is characterized in that when the Reynolds number is 100-400, the parameter ranges of the channel height, the rough unit height and the channel contracted flow diameter are 150-400 μm, 15-45 μm and 179-663 μm respectively.

7. The method and application of using the structured rough reinforced microchannel heat transfer performance of claim 1, wherein the material is selected from the group consisting of low alloy steel, stainless steel, copper-nickel alloy, and other metals with certain plasticity.

8. The use of the method of claim 1 wherein the structured asperity is fabricated from, but not limited to, a common metal rectangular microchannel roll, stamping, damascene or paste.

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