Calcuating energy from Air Tank

[Kayne]

Hi,

I was working with my Air compressor today and was wondering if there is a way to calculate the amount of work or energy that is stored within a air tank? The air compressor is a 2.5hp, 112L/m 120Psi and volumes is 40L.

From these details can the work be calculated or is more information required.

Any guidance would be great

Thanks

 

[CFDFEAGURU]

Yes, it can be calculated.

First you need to determine the mass of the air stored in the tank at the final temperature and pressure of the air in the tank.

Second use the gas constant for air at standard conditions. R = 287 J/(kg-K) (be careful with standard conditions as they are not always standard)

Next calculate the Specific Heat at Constant Volume using the above values. Gamma for air is 1.4

Next the energy in joules per kilogram can be calculate by multiplying the Specific Heat at Constant Volume by the temperature of the air.

Lastly, the total energy is the above energy times the mass of air. The ending units will be Joules.

 

[Kayne]

This sounds easier then it looks, so please bare with me on this explanation

Yes, it can be calculated.

First you need to determine the mass of the air stored in the tank at the final temperature and pressure of the air in the tank.

So I have taken real measurements off the compressor which were
Temperature = 33°C
Pressure = 120Psi

Can you please explain in a little more detail how to calculate the Mass, and what variables are required?

Second use the gas constant for air at standard conditions. R = 287 J/(kg-K) (be careful with standard conditions as they are not always standard)

Next calculate the Specific Heat at Constant Volume using the above values. Gamma for air is 1.4

The air tank volume = 40 litres
Temperature = 33°C
Pressure = 120Psi
Gamma = 1.4
gas constant = R = 287 J/(kg-K)

[itex] Specific heat = Mass \times Gas Constant \times Pressure \times Temperature \times Volume^{gamma} [/itex]

Am I on the correct path with the equation

Next the energy in joules per kilogram can be calculate by multiplying the Specific Heat at Constant Volume by the temperature of the air.

Lastly, the total energy is the above energy times the mass of air. The ending units will be Joules.

Do you mean the temperature of the air inside the tank or ambient temperature which was 29°C

[itex] Energy (J/kg) = Specific Heat \times Air temp [/itex]

[itex] Joules = Energy \times Mass[/itex]

Are the explanation correct for the comments which you have made.

Thanks for your time with this

 

[CFDFEAGURU]

Do you have access to a thermodynamics book?

 

[PJC01]

for your question! To calculate the energy stored in an air tank, we first need to understand the relationship between pressure, volume, and energy. The energy stored in a compressed gas is proportional to its pressure and volume, according to the ideal gas law (PV=nRT). In this equation, P is pressure, V is volume, n is the number of moles of gas, R is the ideal gas constant, and T is temperature.

To calculate the energy stored in your air tank, we need to know the number of moles of gas present. This can be calculated using the ideal gas law, but we would need to know the temperature of the gas as well. Without this information, it is not possible to accurately calculate the energy stored in the tank.

Additionally, the power (2.5hp) and flow rate (112L/m) of the air compressor do not directly correspond to the energy stored in the tank. These values are related to the rate at which the air is being compressed and the power required to do so, but do not directly reflect the total energy stored in the tank.

If you are looking to determine the energy output of the air compressor, you may be able to estimate it by measuring the time it takes to fill the tank and the power of the compressor. However, this would not take into account any energy losses or inefficiencies in the system.

In summary, more information is needed to accurately calculate the energy stored in an air tank. If you are looking for an estimate, measuring the time and power of the compressor may provide some indication, but it would not be a precise calculation. I hope this helps clarify the relationship between pressure, volume, and energy in a compressed gas system.