Download presentation

Presentation is loading. Please wait.

Published byDillon Criste Modified over 2 years ago

1
ENTC 370PROF. ALVARADO1 THERMODYNAMICS LAB Mass and Energy Analysis of Control Volumes Polytropic Processes ENTC - 370

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

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

4
ENTC 370PROF. ALVARADO4 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=c p /c v =1.4 for air. Graph from www.taftan.com

5
ENTC 370PROF. ALVARADO5 Polytropic Process Boundary work:

6
-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. 1.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. 2.Plot ln(P) versus ln(v) and find n: a.For each run, on a separate graph, plot ln(P) [on the ordinate (vertical) axis] versus ln(v) [on the abscissa (horizontal) axis]. b.Determine the polytropic exponent n by using a linear model of each run. Also find the correlation coefficient R 2. 3.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)? ENTC 370PROF. ALVARADO6 Problem 1: Polytropic Process (Excel) Conversion factor: 6.894 kPa=1 PSI ºK = ºC+273.15 R= 0.286 KJ/(kg ºK) for air

7
ENTC 370PROF. ALVARADO7 Turbines and Compressors Analysis for steady state systems, Energy balance:

8
ENTC 370PROF. ALVARADO8 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 ( ke) -Turbine inlet area -Plot the power output against the outlet pressure P1,T1,V1 P2,x2,V2

9
ENTC 370PROF. ALVARADO9 Problem 2: Steam Turbine (EES)

10
ENTC 370PROF. ALVARADO10 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

Similar presentations

OK

Fig. 17-11 The net work done by the system in the process aba is –500 J.

Fig. 17-11 The net work done by the system in the process aba is –500 J.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on channel estimation Ppt on telephone etiquettes Ppt on chromosomes and genes E paper display ppt online Themes free download ppt on pollution Ppt on new zealand culture for kids Ppt on history of atom structure Ppt on girl child abortion Ppt on division as equal sharing worksheets Ppt on review of related literature format