How Does Temperature Affect Pressure in a Sealed Fuel Tank?

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Increasing the outside temperature of a sealed fuel tank will raise the pressure inside due to the increased vapor pressure of the fuel. The tank, initially containing 3/4 liquid and 1/4 gas, will always have both liquid and vapor present until the temperature is high enough to evaporate all the liquid. The pressure correlates with the equilibrium vapor pressure, which rises with temperature, while the liquid's incompressibility means the tank's volume remains fixed. As the temperature increases, the vapor-to-liquid ratio changes, but pressure consistently rises. Ultimately, the relationship between temperature and pressure in a sealed tank is governed by thermodynamic principles.
hybro
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Hi all,
I have some troubles with some basics thermodynamic rules. I have a sealed tank filled with fuel at Patm and at a temperature T. In this tank after filling, is composed of 3/4 liquid and 1/4 gas. I was wondering how the pressure inside the tank will change if we change the boundaries conditions (outside temperature). Will the pressure rise in the tank if the outside temperature goes up? Is it due to the vapor created because of the temperature variation (vapor pressure of the fuel?) or because of the liquid which exerce a pressure on the surface of the tank ?
With the perfect gas law we know that with the temperature the pressure will rise with the temperature but the vapor/liquid ratio will change too. And fuel is like incompressible so the tank expands too ?
Thank you for your help guys !
 
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hybro said:
Hi all,
I have some troubles with some basics thermodynamic rules. I have a sealed tank filled with fuel at Patm and at a temperature T. In this tank after filling, is composed of 3/4 liquid and 1/4 gas. I was wondering how the pressure inside the tank will change if we change the boundaries conditions (outside temperature). Will the pressure rise in the tank if the outside temperature goes up? Is it due to the vapor created because of the temperature variation (vapor pressure of the fuel?) or because of the liquid which exerce a pressure on the surface of the tank ?
With the perfect gas law we know that with the temperature the pressure will rise with the temperature but the vapor/liquid ratio will change too. And fuel is like incompressible so the tank expands too ?
Thank you for your help guys !
If you raise the temperature in the tank (with the tank volume held fixed), the pressure in the tank will increase. The pressure in the tank will be equal to the equilibrium vapor pressure of the substance, which increases with temperature (neglecting hydrostatic pressure variation in the liquid).
 
So that means we will always have liquid and vapor in the tank ? impossible to have only vapor if the temperature rise ?
 
hybro said:
So that means we will always have liquid and vapor in the tank ? impossible to have only vapor if the temperature rise ?
No. Under certain starting conditions, of course, after you have raised the temperature enough, all the liquid will have evaporated. But, even here, the pressure rises monotonically with temperature.
 

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