CN115523784A

CN115523784A - Method for enhancing heat transfer performance of micro-channel by using structured roughness and application

Info

Publication number: CN115523784A
Application number: CN202110708535.4A
Authority: CN
Inventors: 安萨里穆尼布卡西姆; 曹保鑫; 周国兵
Original assignee: North China Electric Power University
Current assignee: North China Electric Power University
Priority date: 2021-06-25
Filing date: 2021-06-25
Publication date: 2022-12-27

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 for enhancing heat transfer performance of micro-channel by using structured roughness and application

Technical Field

The invention belongs to the field of passive enhanced heat transfer, and particularly relates to a method for enhancing the heat transfer performance of a microchannel by utilizing structured roughness and application thereof, wherein the method comprises a micro-electromechanical device, a fuel cell, a solar cell, a heat exchanger and the like.

Background

Thermal management plays an important role in many engineering applications, particularly in the design of microelectronic devices. Advances in electronics technology place higher demands on the power density of electronic devices. Therefore, heat transfer on a microscopic level presents a tremendous need and opportunity for the study and development of thermal management systems. In addition, with the development of the modern microelectronic industry, the packaging density is higher and higher, and the heat dissipation capability is required to be stronger and stronger. In the past, extensive research has been conducted on equal-section smooth microchannels due to limitations in the manufacturing process. However, new enhanced heat transfer structures (micro-fins, grooves and different channel shapes) are increasingly being used to improve flow mixing in laminar flow, thereby enhancing heat transfer in laminar flow in microchannels with smaller hydraulic diameters. However, these innovative configurations also result in higher pressure drop, despite improved heat transfer. Therefore, it is necessary to design such a microchannel structure to improve the overall heat transfer performance with a limited channel size.

Disclosure of Invention

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

On one hand, 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 is arranged along the length of the rectangular channel, and the normal direction of the rough wall surface is vertical to the flowing direction of fluid in the microchannel.

Preferably, the coarse cell shape may be, but is not limited to, triangular, rectangular, sinusoidal.

Preferably, the sides of the microchannels are smooth walled.

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

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

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

Preferably, the material of construction can be, but is not limited to, metals with certain plasticity such as low alloy steel, stainless steel, copper-nickel alloy, and the like.

Preferably, the structured rough microchannels may be fabricated, but are not limited to, by rolling, stamping, inlaying, or pasting conventional metal rectangular microchannels.

The invention has the beneficial effects that:

the method for enhancing the heat transfer performance of the micro-channel by using the structured roughness has strong disturbance to the flow, when the fluid flows through the rough surface, the flow state of the fluid is periodically changed along with the flow path due to the existence of triangular, rectangular or sinusoidal wave peaks, and the flow speed is large or small, so that the effect of enhancing the heat transfer is achieved. Although the rough surface can increase the flow resistance to a certain extent, the flow resistance does not suddenly rise through the optimized design, and the rising amplitude of the calculated resistance coefficient is small. In particular, the sine wave rough micro-channel has inconspicuous resistance coefficient rise due to the fact that the flow channel is excessively gentle. Has better comprehensive performance coefficient, as shown in figure 3. Channels with triangular surface roughness are preferred to smooth channels

Overall performance improvement of 7% when =50

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

The difference in performance in the 250 range does not exceed 10%.

Drawings

FIG. 1 is an isometric view of example 1 of a method for enhancing the heat transfer performance of microchannels using structured asperities (a) having a triangular shape, (b) having a rectangular shape, and (c) having a sinusoidal waveform;

FIG. 2 is a schematic cross-sectional view of a rough microchannel with different cross-sectional shapes, wherein (a) is a triangle, (b) is a rectangle, and (c) is a sine wave.

FIG. 3 is a diagram showing the effect of the comprehensive performance coefficient of the rough micro-channel with different cross-sectional shapes.

Detailed Description

The invention provides a method for strengthening heat transfer through a structured rough strengthening microchannel, which has the advantages of good strengthening heat transfer effect, small flow resistance loss and simple processing and manufacturing, and an application thereof. It can be made of copper, stainless steel and other materials by rolling and die pressing. The invention is further described with reference to the following figures and specific examples. It should be emphasized that the following description is merely exemplary in nature and is in no way intended to limit the scope of the invention or its applications.

Example 1

The method for enhancing the heat transfer performance of the micro-channel by using the structured roughness is shown in the attached figures 1 and 2. The length L of the three structured rough micro-channels is 12mm, the width W of the three structured rough micro-channels is 12.7mm, the width omega of the roughness element is 100 mu m, the height r of the three structured rough micro-channels is 30 mu m, the pitch s of the three structured rough micro-channels is 250 mu m, and the height Hc of the contraction micro-channels is 190 mu m. The three types of rough surfaces are all aligned. The three structured rough microchannels have a combined performance coefficient of up to 1.35 in a Reynolds number range of 50 to 250.

Claims

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.