1. ES 202 Fluid and Thermal Systems Lecture 6: ES 201 Review & Steady State Devices (12/12/2002)

2. Assignments Reading: –Cengel & Turner Section 11-2, 11-3 –ES 201 notes Homework: –5-62E, 5-75 in Cengel & Turner –7 problems altogether due on Monday

3. Road Map of Lecture 6 Announcements Revisit problems on hydrostatics –qualitative comparison of hydrostatic force –hanging weight problem Review of ES 201 concepts –Fundamentals of control volume analysis common structure of accounting equation –steady state device: nozzle, diffuser, turbine, compressor, heat exchanger function design assumption modeling assumption

4. Announcements Announcement on problem session –Thursday from 7 pm to 8:30 pm For Section 6 only: –Lab write-up due tomorrow by 5 pm at my office

5. Revisit Hydrostatics Compare the hydrostatic forces acted on Surface AB (not the bottom of the tank) in the following configurations: A B A B A B

6. Revisit Hydrostatics (cont’d) partially submerged condition completely submerged conditions but does not reach the bottom of tank resting at the bottom of tank Will your conclusion be different if the water is filled up to the brim before the weight is lowered? Explain your answer. Consider the following set up. Describe the reading on the balance as the weight is gradually lowered into the water tank. Assume the tank is large enough that no over-flowing occurs. Hint: It may be helpful to consider the following possibilities separately: balance rope

7. ES 201 Review

8. Conservation and Accounting Principles Common structure of accounting equation for an open system: storage = in – out + production The above equation can be expressed in –rate form –finite time form Major difference between the accounting of various extensive properties –means of transport (can be classified as “in” term) –production

9. Production (Physics) The simple book-keeping form does not contain any physics. It is true in general, even in balancing your check book. The “physics” part comes in through the prescription of the production and “in” terms. What is the production and “in” for the followings: –mass –energy –momentum –entropy

10. In-Class Exercise Write down the accounting equation for energy in rate form for an open system

11. Steady-State Devices List the purpose, design assumption and modeling assumption for the following devices: –nozzle –diffuser –turbine –compressor, fan, blower, pump –heat exchanger

12. Turbine Steam turbine Water turbine (hydro-electricity) Wind turbine (hill slopes) Gas turbine engine –compressor –combustor –turbine (multiple rotor-stator stage)