Air cross-swept single-tube forced convection heat transfer teaching experiment device and application method

Abstract

The invention discloses an air cross-swept single-tube forced convection heat transfer teaching experiment device and an application method. The device comprises an experiment wind tunnel, an experiment circular tube heating power measurement circuit and an experiment circular tube temperature control and measurement part, wherein the experimental wind tunnel comprises an experimental section, a wind tunnel contraction section, a wind tunnel stabilization section and a wind tunnel diffusion section, one end of the experimental section is communicated with the wind tunnel contraction section, the wind tunnel contraction section is communicated with the wind tunnel stabilization section, and the other end of the experimental section is communicated with the wind tunnel diffusion section; the two ends of the experimental circular tube are inserted into two heat dissipation aluminum blocks respectively, semiconductor pieces are installed on the outer sides of the two heat dissipation aluminum blocks respectively, and heat dissipation fans are installed on the outer sides of the semiconductor pieces. By protecting the temperatures of the two ends of the experimental circular tube, the measurement deviation of an experimental result can be controlled within 10%, the measurement fluctuation degree can be controlled within 5%, and the measurement precision not only completely meets the requirements of experimental teaching, but also can meet the requirements of scientific research experiments.

Description

technical field [0001] The invention belongs to the technical field of experimental teaching of energy and power majors in colleges and universities, and in particular relates to an air-sweeping single-tube forced convection heat transfer teaching experimental device and a use method. Background technique [0002] Air-swept single-tube forced convection heat transfer 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 heat exchange tube, the core component of the experimental device, is directly installed in the square air flow channel, and the two ends of the tube are embedded in the air channel shell, and the heat is directly energized. When it exchanges heat with the incoming air, because the end of the circular tube cannot conduct convective heat exchange with the air, the temperature gradient...

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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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