1 / 10

THERMODYNAMICS LAB Mass and Energy Analysis of Control Volumes Polytropic Processes

THERMODYNAMICS LAB Mass and Energy Analysis of Control Volumes Polytropic Processes. ENTC - 370. Polytropic Process(1). During expansion and compression processes of gases, the following relationship holds:. The coefficient n depends on the process. Polytropic Process(2).

suki-english
Download Presentation

THERMODYNAMICS LAB Mass and Energy Analysis of Control Volumes Polytropic Processes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. THERMODYNAMICS LABMass and Energy Analysis of Control VolumesPolytropic Processes ENTC - 370 PROF. ALVARADO

  2. Polytropic Process(1) • During expansion and compression processes of gases, the following relationship holds: • The coefficient n depends on the process.

  3. Polytropic Process(2) • During expansion and compression processes of gases, the following relationship holds: • The coefficient n depends on the process.

  4. Polytropic Process • The coefficient n depends on the process: • n=0 , Isobaric process (constant pressure) 5-1 in graph. • n=∞, Isometric process (constant volume) 2-6 in graph. • n=1, Isothermal process (constant temperature) 4-8 in graph. • n=k, Adiabatic process (no heat transfer) 3-7 in the graph. k=cp/cv=1.4 for air. Graph from www.taftan.com PROF. ALVARADO

  5. Polytropic Process • Boundary work: PROF. ALVARADO

  6. Problem 1: Polytropic Process (Excel) • Pressurized air inside a pressure vessel is expanded in a polytropic process using three discharge valves with small, medium and large orifices. The measured temperature and pressure for the process are posted. • Use the ideal gas law, Pv = RT, to compute v for each corresponding P. Use SI units: m3/kg for v, kPa for P and ºK for T. • Plot ln(P) versus ln(v) and find n: • For each run, on a separate graph, plot ln(P) [on the ordinate (vertical) axis] versus ln(v) [on the abscissa (horizontal) axis]. • Determine the polytropic exponent n by using a linear model of each run. Also find the correlation coefficient R2. • Discuss the meaning of your n values, that is, how do the n values compare with n values for other, known processes (see previous slide)? PROF. ALVARADO

  7. Turbines and Compressors • Analysis for steady state systems, Energy balance: PROF. ALVARADO

  8. Problem 2: Steam Turbine (EES) Steam flows steadily (8 kg/sec, mass flow rate) through an adiabatic turbine. The inlet conditions of the steam are 10 MPa, 350 ºC, and 65 m/sec. The exit conditions are 85% quality, and 40 m/sec. The exit pressure varies from 10 kPa to 200 kPa. Determine: -Change in Kinetic Energy (Dke) -Turbine inlet area -Plot the power output against the outlet pressure P1,T1,V1 P2,x2,V2 PROF. ALVARADO

  9. Problem 2: Steam Turbine (EES) PROF. ALVARADO

  10. Individual Lab Report • Introduction: Briefly explain the objectives of the assigned tasks • Data: Present data in tabulated form (use Excel) • Findings or Results: Include plots (EES and Excel) for each data set and the corresponding correlation equations and correlation values • Conclusions: Comment on the tasks performed and provide concluding remarks PROF. ALVARADO

More Related