A liquid has a molar volume of 0.2 L/mol at 400 K and 4 bar. This liquid is compressed with a pump that operates at steady-state and adiabatically. The liquid enters the pump at a rate of 3 mol/s, at a temperature of 400 K and pressureof 4 bar and exits at a pressure of 20 bar. The liquid has the following properties which can be used (if needed) in the solution: • Coefficient of thermal expansion, αV = 2 x 10-3 K-1 • Isothermal compressibility factor, κT = 4 x 10-5 bar-1 • Cp = Cv = 30 J/mol-K Find the following: A) Work done by the pump B) Temperature of the liquid leaving the pump C) Molar volume of the liquid leaving the pump
A liquid has a molar volume of 0.2 L/mol at 400 K and 4 bar. This liquid is compressed with a pump that operates at steady-state and adiabatically. The liquid enters the pump at a rate of 3 mol/s, at a temperature of 400 K and pressureof 4 bar and exits at a pressure of 20 bar.
The liquid has the following properties which can be used (if needed) in the solution:
• Coefficient of thermal expansion, αV = 2 x 10-3 K-1
• Isothermal compressibility factor, κT = 4 x 10-5 bar-1
• Cp = Cv = 30 J/mol-K
Find the following:
A) Work done by the pump
B) Temperature of the liquid leaving the pump
C) Molar volume of the liquid leaving the pump
A. Work done by the pump
The work done by the pump is given by the following formula:
where
- n is the number of moles of liquid entering the pump per unit time ()
- R is the universal gas constant ()
- T is the temperature of the liquid entering the pump ()
- P1 is the pressure of the liquid entering the pump ()
- P2 is the pressure of the liquid leaving the pump ()
- κT is the isothermal compressibility factor of the liquid ()
Substituting the given values, we get the work done by the pump as follows:
B. Temperature of the liquid leaving the pump
The temperature of the liquid leaving the pump can be found using the following formula:
where
- T1 is the temperature of the liquid entering the pump ()
- P1 is the pressure of the liquid entering the pump ()
- P2 is the pressure of the liquid leaving the pump ()
- γ is the adiabatic index of the liquid ()
Substituting the given values, we get the temperature of the liquid leaving the pump as follows:
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