A simplified calculation method of convective heat transfer coefficient for large-diameter corrugated pipe

Abstract

The application discloses a simplified calculation method of a convection heat transfer coefficient suitable for a large-diameter corrugated pipe, and the simplified calculation method comprises the following steps: obtaining an inlet wind speed of the large-diameter corrugated pipe and a pipe radius of the large-diameter corrugated pipe; calculating a cross-section wind speed distribution and a cross-section average wind speed of a heat transfer fully developed section according to the inlet wind speed and the pipe radius; and calculating the convection heat transfer coefficient according to the cross-section average wind speed. The calculation method can simplify the calculation process of the convection heat transfer coefficient, and the convection heat transfer coefficient of the large-diameter corrugated pipe during ventilation cooling can be calculated simply, quickly and accurately without experiments, so that the cost and time for obtaining the convection heat transfer coefficient are saved, and the working efficiency of thermal coupling analysis of large-volume components is improved.

Description

Technical Field

[0001] This invention belongs to the field of heat exchange technology, and in particular relates to a simplified calculation method for the convective heat transfer coefficient applicable to large-diameter corrugated pipes. Background Technology

[0002] Ventilation cooling is a common technique used in the construction of large-volume concrete structures to mitigate the rapid temperature rise caused by the concentrated release of internal hydration heat. Furthermore, to more effectively control hydration heat and the internal temperature of the concrete, finite element thermo-mechanical coupling analysis is required before construction. The convective heat transfer coefficient is a crucial parameter in this analysis. While the heat transfer coefficients of common materials can be determined based on empirical data, the heat transfer coefficient of large-diameter prestressed corrugated pipes used as ventilation ducts in large-volume concrete ventilation cooling requires experimental testing. Testing the convective heat transfer coefficient involves complex steps such as specimen preparation, sensor setup, specimen heating, and testing, requiring specialized personnel. Therefore, a simple and convenient method for calculating the convective heat transfer coefficient suitable for large-diameter corrugated pipes is needed. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a simplified calculation method for the convective heat transfer coefficient of large-diameter corrugated pipes. This method simplifies the calculation process for the convective heat transfer coefficient of large-diameter corrugated pipes, allowing for a quick, easy, and relatively accurate calculation of the convective heat transfer coefficient of large-diameter prestressed corrugated pipes during ventilation and cooling without the need for experiments.

[0004] To achieve the above objectives, the technical solution adopted by this invention is: to provide a simplified calculation method for the convective heat transfer coefficient applicable to large-diameter corrugated pipes, which includes the following steps:

[0005] S1 obtains the inlet wind speed and pipe radius at the inlet of the large-diameter corrugated pipe;

[0006] S2 calculates the cross-sectional wind speed distribution and average cross-sectional wind speed of the fully developed heat exchange section based on the inlet wind speed and the pipe radius;

[0007] S3 calculates the convective heat transfer coefficient based on the average wind speed of the cross section.

[0008] Furthermore, the simplified calculation method for the convective heat transfer coefficient of large-diameter corrugated pipes as described above is characterized in that: in step S2,

[0009] The cross-sectional wind speed distribution v(r) of the fully developed heat transfer section is calculated using the following formula, which is a function of the distance r from the center of the section:

[0010]

[0011] The cross-sectional average wind speed v of the fully developed heat exchange section is calculated using the following formula. m :

[0012]

[0013] In the formula, R is the pipe radius of the bellows, and v in This refers to the inlet wind speed.

[0014] Furthermore, the simplified calculation method for the convective heat transfer coefficient of large-diameter corrugated pipes as described above is characterized in that: in step S3,

[0015] The convective heat transfer coefficient is calculated using the following formula:

[0016]

[0017] In the formula, v m The average wind speed of the cross section for fully developed heat exchange.

[0018] The beneficial technical effects of this invention are as follows:

[0019] This invention simplifies the calculation formula for the convective heat transfer coefficient by establishing a direct relationship between the convective heat transfer coefficient and the inlet wind speed and pipe radius. This simplified formula allows for the quick and easy calculation of the convective heat transfer coefficient of large-diameter prestressed corrugated pipes during ventilation and cooling, eliminating the need for convective heat transfer coefficient testing. This saves on the cost and time of obtaining the convective heat transfer coefficient and improves the efficiency of thermo-mechanical coupling analysis of large-volume concrete. Attached Figure Description

[0020] Figure 1 This is a flowchart of the simplified calculation method for the convective heat transfer coefficient of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0022] This invention provides a simplified calculation method for the convective heat transfer coefficient of large-diameter corrugated pipes, which includes the following steps: Figure 1 As shown:

[0023] S1 obtains the inlet wind speed v at the inlet of the large-diameter corrugated pipe. in and pipe radius R;

[0024] S2 is based on the inlet wind speed v in Calculate the cross-sectional wind speed distribution v(r) and average cross-sectional wind speed v of the fully developed heat exchange section using the pipe radius R. m ,

[0025] The cross-sectional wind speed distribution v(r) is a function of the distance r from the center of the cross-section: The average wind speed across the cross section is: In the formula, R is the pipe radius of the bellows, and v in This refers to the inlet wind speed.

[0026] S3 is based on the average wind speed v of the cross section of the fully developed heat exchange section. m The convective heat transfer coefficient h is calculated using the following formula:

[0027] In the formula v m The average wind speed of the cross section for fully developed heat exchange.

[0028] In summary, this invention provides a simple and quick way to calculate the convective heat transfer coefficient of large-diameter corrugated pipes (diameter > 100 mm) during ventilation and cooling, using only two unknowns: inlet wind speed and pipe radius. Verification has shown that this calculation method is effective for large-diameter corrugated pipes with a diameter > 100 mm, under conditions of inlet wind speed v... in It has high accuracy at speeds greater than 7.8 m / s.

[0029] The following is an illustration through specific examples:

[0030] Step 1: Obtain the pipe radius and the inlet wind speed at the pipe inlet. The pipe radius is R = 0.05m, and the inlet wind speed is v. in =11.4 m / s;

[0031] Step 2: Calculate the cross-sectional wind speed distribution and average cross-sectional wind speed of the fully developed heat exchange section based on the inlet wind speed, and obtain the cross-sectional wind speed distribution as follows: The average wind speed across the cross section is

[0032] Step 3, calculate the convective heat transfer coefficient, and obtain the convective heat transfer coefficient as follows:

[0033] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art based on the technical solutions and inventive concepts disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. A simplified calculation method for the convective heat transfer coefficient applicable to large-diameter corrugated pipes, comprising the following steps: S1 obtains the inlet wind speed and pipe radius at the inlet of the large-diameter corrugated pipe; S2 calculates the cross-sectional wind speed distribution and average cross-sectional wind speed of the fully developed heat exchange section based on the inlet wind speed and the pipe radius; S3 calculates the convective heat transfer coefficient based on the average wind speed of the cross section; In step S2, The cross-sectional wind speed distribution of the fully developed heat exchange section is calculated using the following formula. It is a function of the distance r from the center of the cross section: The average cross-sectional wind speed of the fully developed heat exchange section is calculated using the following formula. : In the formula, R is the pipe radius of the bellows. Inlet wind speed; In step S3, The convective heat transfer coefficient is calculated using the following formula: In the formula, The average wind speed of the cross section for fully developed heat exchange.

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