Discussion: Is the volume of gas the same in different places (plains and plateaus)?

PV=nRT; when pressure changes, volume also changes. The system acts like a closed environment; when the system pressure remains constant, its volume does not change.

The pressure in the system is always 8 KP; the pressure remains constant and the volume also remains constant, and this has nothing to do with whether it is a plain or a plateau

When the process conditions are the same, the gas volume is naturally the same as well. I discussed this issue with my supervisor a few days ago, and he said that temperature differences in different regions cause variations in the volume of gas. I thought to myself, if the manufacturing conditions are the same, how can there be differences? But in design, gases are generally represented using symbols.

Reply to 1# Eguting: The pressure specified in the question posed by the moderator is 8 KP for the system, but it is not clear whether this refers to gauge pressure or absolute pressure. For now, let’s assume it is gauge pressure, namely 8 KP(G). In that case, the volume of gas at 8 KP(G) is different in plains and plateaus. As we all know, the atmospheric pressure in coastal plains is 103 KPA. Taking Lanzhou as an example for the plateaus, the atmospheric pressure there is 83 KPA. Therefore, the absolute pressure in the plains is 103 + 8 = 111 KPA, while in Lanzhou it is 83 + 8 = 91 KPA. Thus, the gauge pressure in both places is the same, but the volume must differ.

This post was last edited by zpg on 2011-2-15 09:56. The friend above is correct; different altitudes result in different air pressures. At the same gauge pressure, the absolute pressure of a system varies as well. On the Nyenchen Tanglha Mountains at an altitude of around 5,500 meters, I measured the local air pressure, which was only about 50 kPa – half of the standard atmospheric pressure. At that altitude, the air density at 0°C is 0.644 kg/m3, compared to 1.29 kg/m3 at sea level. You can calculate the gauge pressure of 8 kPa by yourself. . Plateau areas have a significant impact on gas compressor-type equipment, such as blowers and vacuum pumps. Due to the thin air, the air intake volume of blowers must be adjusted, resulting in higher energy consumption compared to areas at lower elevations. . With a lower back pressure of the vacuum pump, at the same pumping pressure and volume, vacuum pumps in high-altitude areas consume less energy due to their lower compression ratio. . Thin air can also have an impact on electrical instruments; for example, in high-altitude areas, air-cooled motors are affected by the thin air in terms of heat dissipation, so it is necessary to take appropriate margins into account during design. There are many such considerations, and the original poster can learn about them gradually through work experience. It’s best to go to the plateau in person and experience how out of breath one gets after just a few steps. .

What was said upstairs is very comprehensive. If you work in a design institute and are assigned projects in different locations, it is natural to request the clients to provide information on meteorological conditions; among these, the local atmospheric pressure is very important. Those involved in process design and instrumentation must take the local atmospheric pressure into account in their calculations and also specify relevant requirements.

Generally, before starting the design process, it is necessary to understand in advance the local natural conditions such as atmospheric pressure, temperature, and wind speed, and these factors must be taken into account during the design

At different altitudes, the atmospheric pressure varies; the atmospheric pressure at high altitudes is not the standard atmospheric pressure at sea level. Of course, this value can also change slightly. Under normal conditions, at 1 atm and 20°C, the density of the atmosphere is about 1.25 Kg/m3; on high plateaus, this value is lower. That is, for a given mass of gas, its volume is larger on high plateaus