Teaching experiment table for critical state observation and p-v-T relationship determination

Abstract

The invention discloses a teaching experiment table for critical state observation and p-v-T relationship determination. The teaching experiment table comprises a bottom cavity, wherein a metal cup is arranged in the bottom cavity; a gap is formed between the metal cup and the inner wall of the bottom cavity; the metal cup is filled with mercury; the part between the upper part of a mercury surface in the metal cup and the inner wall of the bottom cavity is filled with hydraulic oil; a metal gas compression cavity extending into the mercury is arranged in the metal cup; a conduit extending into the mercury is arranged at the bottom of the metal gas compression cavity; a quartz glass tube is arranged at the top of the metal gas compression cavity; the metal gas compression cavity and the quartz glass tube are filled with a fluid working medium; an experiment temperature control part for controlling the experiment temperature is arranged at the outer side of the quartz glass tube. A glass compression cavity is replaced with the metal compression cavity, a common glass tube is replaced with the thick-wall quartz glass tube, and a gourd-shaped glass cavity used for conventional gas compression is changed into the metal cavity through a sealed design, so that the pressure resistance and the security of the experiment table are greatly improved.

Description

technical field [0001] The invention relates to experimental teaching in the technical field of energy and power, and in particular to a teaching experiment platform for critical state observation and p-v-T relationship determination, which is used for the teaching of energy and power critical state observation and p-v-T relationship determination professional course experiments. Background technique [0002] "Critical state observation and p-v-T relationship measurement experiment" is a course measurement experiment set up in domestic thermodynamics, physical chemistry, thermal engineering and other courses. At present, the carbon dioxide P-V-T relationship instrument used in this experiment for undergraduates in China uses Carbon dioxide is encapsulated in a glass container, the upper part of the glass container is a cylindrical long glass tube, and the lower part is a gourd-shaped cavity. Use a pressure pump to send the pressure oil into the high-pressure container, and t...

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Problems solved by technology

[0005] The containers are all made of ordinary glass. The wall thickness of the glass container is generally 1-3mm, and the inner and outer parts of the gourd-shaped lower part of the container are under pressure. Therefore, the glass container should not be used under excessive pressure.

In this experiment, carbon dioxide is pressurized by a pressure pump. Due to the high critical pressure of carbon dioxide, the highest pressure in the experiment will reach 10MPa. It is obviously dangerous to conduct experiments under such a large pressure. Most of the manufacturers do not have the production and manufacturing qualifications of pressure vessels, which further exacerbates the risk of using this instrument in the teaching process

[0006] 2. The length of the liquid column after carbon dioxide liquefaction is too small

[0007] In the experimental process of this experiment, it is necessary to completely compress carbon dioxide into a liquid state at a certain temperature, and then process the experimental data by observing the length of the liquid column. The accuracy of the experimental results is directly related to the accuracy of the liquid column measurement. Since the length of the liquid column after liquefaction of carbon dioxide is very short, about 15mm, and the minimum scale of the scale is 1mm, it is obviously not easy to read such a short liquid column

In addition, when the liquid is completely liquefied and then compressed, the pressure will rise rapidly. Because the liquid column of carbon dioxide is too short, it is easy for students to pressurize too fast in the experiment and cause the glass tube to burst due to overpressure, which will cause danger.

[0008] 3. The experiment opening time range is limited

[0009] Due to the limitation of the purchase cost of the teaching experiment bench, most of the circulating baths attached to the experiment bench used by colleges and universities do not have the cooling function

The critical pressure of carbon dioxide is 30.98°C. In the experiment, it is necessary to conduct a test below the critical temperature. Since the constant temperature bath without refrigeration function needs to be at least 5-10°C higher than the room temperature to be stable, this experiment is performed in summer or spring and autumn. When the room temperature is high, it may not be opened normally

[0010] Since carbon dioxide is very easy to obtain, and its thermophysical property data is more familiar than other working fluids, the "critical state observation and p-v-T relationship determination experiment" has only used carbon dioxide as the working medium from the beginning, so that the experimental platform has more than many problems

In recent years, due to the marketization of teaching experiment instruments, the professionalism of instrument developers is often slightly lacking, and most of the more professional researchers no longer pay attention to it, so the teaching experiment has not been improved for a long time

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