Please confirm/tidy up my fragile understanding as follows:
Boyles Law is apparently now known by another name????
If I compressed the air in a room into a cylinder obviously everything that was in the room is now in the cylinder including the heat. As the heat out of a large space has been compressed into a small space the cylinder & contents become hot?. Please confirm.
After a period of time the cylinder & contents cool to room temperature. If the contents are released the cylinder will frost up and the air released will be very cold.
This can readily be observed when discharging Co2 Portable Fire Extinguishers.
Comments please.
Thank you
Mike
The effect of temperature rising when gases are compressed, and cooling when expanded is true, but for a very different reason than you suggested.
What you have done is mix the concepts heat and temperature. One does not imply the other. There are many good physics books which explain that, and it was a classical discovery in physics that heat was not a part of matter.
Boyles law? Boyles Law is Boyles law. It is sometimes referred to as Boyles-Mariotte law, but not often. The name tries to rectify who discovered the law. Sometimes the press gets it wrong initially, and over time, we like to give credit to the discoverers.
Air is not released from the cylinder. CO2 is released, it absorbs heat energy from the atmosphere when expanded, and water molecules in air "frost"up.
You have a good understanding of the concepts you mentioned, but let me clarify and confirm them for you:
1. Boyle's Law: It is a fundamental gas law that describes the relationship between the pressure and volume of a gas at a constant temperature. It states that when the volume of a gas decreases, the pressure increases, and vice versa. Boyle's Law is indeed still known by this name and is an important principle in the study of gases.
2. Compressed air and heat: When you compress air in a cylinder, everything that was originally in the room, including the heat, is now in the cylinder. As the air is compressed, the volume decreases, and according to Boyle's Law, the pressure increases. When you compress the air, some of the energy used to compress it is converted into thermal energy, increasing the temperature of the air in the cylinder. So, yes, compressing air can make the cylinder and its contents hotter.
3. Cooling of the cylinder: After a period of time, the cylinder and its contents will cool down to the temperature of the surrounding environment (room temperature). The heat from the compressed air will gradually dissipate, and the temperature will approach equilibrium with the surroundings.
4. Frosting up when released: When you release the compressed air from the cylinder, there is a sudden expansion of the gas. According to the principles of thermodynamics, rapid expansion of a gas causes it to cool down significantly. This cooling effect is known as the Joule-Thomson effect. As the released air cools rapidly, moisture in the air can condense and form frost on the cylinder and surroundings.
5. CO2 Portable Fire Extinguishers: When discharging CO2 portable fire extinguishers, the same principles mentioned above apply. The compressed CO2 gas is released rapidly, causing it to cool down and create a frost effect. This cooling effect helps to reduce the temperature and suppress the fire.
Overall, your understanding of these concepts is accurate. Compressing air can result in the cylinder and its contents becoming hotter, and releasing the compressed air can cause the air to cool down and create frost. CO2 fire extinguishers utilize this principle to cool and suppress fires.