{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

throttle example - 2 at the inlet as H in = 199 J/mol To...

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Example: Chapter 6 Throttling Process Calculation using SRK Equation of State Nitrogen at 100 bar and 35 o C is expanded (throttled) through a partially opened valve to a pressure of 2 bar. What is the temperature of the N 2 downstream from the valve? Solution The flow through the valve is assumed to take place quickly so that there is not much time for heat transfer. Thus, the system is assumed to be adiabatic. This is a steady-state, adiabatic system, in which no work is done so that the first law simplifies to Δ H = 0 H in = H out If N 2 were an ideal gas at these conditions, then H would only depend on temperature and the outlet temperature would be 35 o C. For a real gas, the temperature will be different from 35 o C because H depends on both temperature and pressure for a non-ideal gas. The equations-of-state spreadsheet (Cubic EOS. xls) was used to determine how much N 2 differs from an ideal gas. Inlet conditions : 100 bar, 35 o C 100 bar = 10 MPa 35 o C = 308 K The Cubic EOS program for the Soave-Redlich-Kwong EOS calculates an enthalpy for N
Image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 2 at the inlet as H in = 199 J/mol To determine the outlet temperature, the temperature in the EOS program was adjusted , for a pressure of 0.2 MPa (2 bar) until the enthalpy was 199 J/mol H out = 199 J/mol It took about 6 tries to get a temperature to 4 significant figures, which is more accurate then justified by the data. The exit temperature from the Cubic EOS program is 280.7 K, which is rounded to 281 K, which is equal to 8 o C. Thus expansion through a throttle valve decreased the temperature by 27 o C. Check- this makes sense, the temperature usually decreases for throttling processes. According to the SRK equation, the initial compressibility factor was 0.92, which means the gas was non-ideal initially so it would be expected to behave as a non-ideal gas. Moreover, the initial pressure was quite high (100 bar is about 1470 psia) so non-ideal behavior is expected....
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern