An air-swept single-tube forced convection heat transfer teaching experimental device and using method

Abstract

An air-swept single-tube forced convection heat transfer teaching experimental device and use method, comprising an experimental wind tunnel, an experimental circular tube heating power measurement circuit, and an experimental circular tube temperature control and measurement part; wherein, the experimental wind tunnel includes an experimental section, a wind The tunnel contraction section, the wind tunnel stable section and the wind tunnel diffusion section, one end of the experimental section is connected with the wind tunnel contraction section, the wind tunnel contraction section is connected with the wind tunnel stable section, and the other end of the experimental section is connected with the wind tunnel diffusion section; The two ends of the round tube are respectively inserted into two heat-dissipating aluminum blocks, a semiconductor chip is installed on the outside of the two heat-dissipating aluminum blocks, and a heat-dissipating fan is installed on the outside of the semiconductor chip. By protecting the temperature at both ends of the experimental circular tube, the invention can control the measurement deviation of the experimental results within 10% and the measurement fluctuation within 5%. Require.

Description

technical field [0001] The invention belongs to the technical field of experimental teaching of energy and power majors in colleges and universities, and particularly relates to an experimental device for teaching forced convection heat transfer with an air traversing single-tube and a method for using it. Background technique [0002] The forced convection heat transfer of air swept single-tube is a course experiment widely offered in the "Heat Transfer" course in domestic colleges and universities. At present, there are some problems in the experimental benches used in domestic colleges and universities. First of all, the core element of the experimental device, the heat exchange circular tube, is directly installed in the square air duct, and the two ends of the circular tube are embedded in the air duct shell, which is directly energized to heat it. When it exchanges heat with the incoming air, the end of the round tube cannot conduct heat exchange with the air, resultin...

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Problems solved by technology

The inventor used an infrared thermal imager to measure the temperature on the surface of the circular tube experimentally. The results showed that when the central temperature of the circular tube was 80°C, the temperature gradient on the surface of the circular tube even exceeded 30°C. Such a large temperature difference obviously cannot be accurately measured. The convective heat transfer of the circular tube

[0003] The deviation between the experimental value and the empirical value of Nu measured by the experimental bench currently used by domestic colleges and universities is generally large. From the experimental reports written by some college students, it is found that the deviation of some experimental benches even exceeds 100%. The temperature gradient changes with the change of the wind speed, so the deviation changes linearly with the wind speed, resulting in obvious system deviation. Such a large deviation in this experiment obviously cannot achieve the desired teaching effect, and even makes the students through the experiment. The Basic Principles of "Heat Transfer" Course Get Wrong Understanding

In addition, the existing experimental benches all use centrifugal fans to realize the flow of air, and the noise is 80-85 decibels. Excessive noise seriously affects the teaching process of teachers and the experimental process of students.

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