Closed System Energy Balance

Рет қаралды 33,064

9 жыл бұрын

An energy balance describes the relationship between molecular potential and kinetic energy, fluid potential energy, fluid kinetic energy, heat, and work.

Пікірлер: 29

@GreenFootprint Ай бұрын

If your system is composed of the two rivers and the pump, then there will be no potential energy change for that system. I guess your system as per your calculation is from pipe inlet to pipe outlet including the pump ? The potential energy will be based on system inlet to system outlet, which is 40 ft.

@jaiminpatel3505 7 жыл бұрын

When you were calculating the potential energy on the yowling cat problem, I think you were meaning to multiply 8.346 to the gravity and height, right?

@apm 7 жыл бұрын

Yes! At 21:49, I used 8.314 instead of 8.346 like I had on the line above. I must have been thinking about the universal gas constant (8.314 J/mol-K).

@joaomarcelino4967 3 жыл бұрын

Hey , how do I know if there is any work done to or by the system?

@apm 3 жыл бұрын

A pump is an example of work done on the system. A generator is an example of work done by the system.

@cloretteangel 4 жыл бұрын

very helpful, thank you!!

@salmaalmansoori5565 9 жыл бұрын

thanke you so much , really helped me

@ferdinandtavarra82 8 жыл бұрын

Thanks a lot..really useful.

@youtubemaster3374 6 жыл бұрын

And the term q u were saying is actually head provided or released?

@apm 6 жыл бұрын

Q is heat added to the system.

@yasminezgb 8 жыл бұрын

Is delta U in our equation equal to Q-W ?? helP !

@apm 8 жыл бұрын

+yasmine bouguezine Delta U is the internal energy change. If there is no kinetic or potential energy change (for the closed system) then, yes, Delta U = Q (heat) - W (work).

@yasminezgb 8 жыл бұрын

+APMonitor.com So i deduce here that... the gains or losses of heat or/and work are not due only to its internal energy like it has always been the case for our teacher ? ,(THANK YOU SIR )

@apm 8 жыл бұрын

Yes, the closed system energy balance should include kinetic and potential energy terms as well. However, in many cases these are negligible.

@yasminezgb 8 жыл бұрын

+APMonitor.com NOW i GOT it , Thank thee SO much ! thou are awesome :)

@alejandrobenavides5035 5 жыл бұрын

damn those imperial units are very confusing what on earth is Btu??

@apm 5 жыл бұрын

BTU = British Thermal Unit. Life is much easier in SI units.

@sedderivativemadera5325 6 жыл бұрын

how did you solve the mass work per mass in ex 2 i cant figure out? My answers are the not same as yours? plss help me. thank you !

@apm 6 жыл бұрын

My solution is shown at 7:15. Did I make a mistake on the unit conversion?

@sedderivativemadera5325 6 жыл бұрын

APMonitor.com when I calculated it my answer is 0.05 . how did you get the 0.33? ☺

@apm 6 жыл бұрын

Thanks for catching that - it may have been a calculator error. The correct answer is 0.05 BTU/lbm or 1.5e-5 kW-hr/lbm.

@sedderivativemadera5325 6 жыл бұрын

APMonitor.com thank you very much! These really help us!

@youtubemaster3374 6 жыл бұрын

That delta u is internal energy isnt it?

@apm 6 жыл бұрын

Delta U is the internal energy.

@goldielocks2720 4 жыл бұрын

Yep

@goldielocks2720 4 жыл бұрын

Thank you. Have you ever heard of this being done on a human?

@apm 4 жыл бұрын

An energy balance on a human? Yes, I think scientists may do this when studying weight loss, diet, and exercise. I couldn't point you to a particular reference, however, but a quick search in the scientific literature may turn up some results.

@youtubemaster3374 6 жыл бұрын

Sir i have no clue what my sir teach me. Or what u are teaching.

@apm 6 жыл бұрын

These videos are part of a Chemical Engineering course on material and energy balances. Here is the complete playlist: kzfaq.info/get/bejne/h7ubdsik2a_cdn0.html I also recommend the LearnChemE channel. You may need some additional background information to understand this material.