Propane in a Container finding pressure and energy

In summary, the conversation discusses an aluminum bottle filled with propane and its various properties. The initial weight and volume of the bottle are given, along with the maximum pressure it can withstand. The questions ask for the initial pressure, quality, and internal energy of the propane, as well as the temperature and quality at maximum pressure and the temperature of the propane when the relief valve is shut. Equations and steps for solving the problems are also provided.
  • #1
acusanelli
9
0

Homework Statement



An aluminum bottle weighs 10 kg when empty and has an internal volume of 20 liters. It is filled with 5 kg of propane (C3H8) at 24 °C. The aluminum bottle is rated for a maximum pressure of 35 bar at which point a relief valve is opened.

a) What are the initial pressure, quality, and internal energy?
b) What temperature will the bottle reach at maximum pressure as it is heated? What
is the quality at this maximum pressure state?
c) The relief valve remains opened until the pressure falls back to 14 bar. If the mass
of propane remaining in the bottle is tenth of its original value, what is the temperature of the propane upon shutting of the relief valve?

The Attempt at a Solution


All I want are the equations I need and how to set the problems up
 
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  • #2
For the first part you can use PV=MRC3H8T to get P.

Neglecting the weight of the Al, if it weighs 10 kg when empty (no C3H8), and then is filled with 5kg of C3H8, how much air is in it? You should now be able to find the quality.
 

1. How is the pressure of propane in a container determined?

The pressure of propane in a container is determined by a combination of factors, including the temperature, volume, and number of moles of propane present. This can be calculated using the ideal gas law equation, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is the temperature in Kelvin.

2. What is the relationship between temperature and pressure in a container of propane?

The relationship between temperature and pressure in a container of propane follows the ideal gas law. As the temperature increases, the pressure inside the container will also increase, assuming the volume and number of moles of propane remain constant. This is due to the increased kinetic energy of the gas molecules, causing them to collide more frequently and with more force against the container walls.

3. How does the volume of a container affect the pressure of propane inside?

The volume of a container has an inverse relationship with the pressure of propane inside. This means that as the volume of the container decreases, the pressure of the propane inside will increase, assuming the temperature and number of moles remain constant. This is because the gas molecules have less space to move around, resulting in more frequent and forceful collisions with the container walls.

4. What is the difference between absolute and gauge pressure in a propane container?

Absolute pressure is the total pressure exerted by the propane in the container, including atmospheric pressure. Gauge pressure, on the other hand, only measures the pressure above atmospheric pressure. For example, if a propane tank has an absolute pressure of 40 psi and atmospheric pressure is 14.7 psi, the gauge pressure would be 25.3 psi.

5. How does the pressure of propane relate to its energy content?

The pressure of propane is directly proportional to its energy content. This means that as the pressure increases, so does the energy content of the propane. This is because the gas molecules are more tightly packed together, resulting in more potential energy. This is why high pressure propane tanks are able to hold more propane and have a higher energy output than low pressure tanks.

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