I did not understand how do you find h4.... And if 4 was superheated what would we do?
@GraydonBob6 күн бұрын
What if you are not given the surface temperature but only the ambient temperature
@tonykaram473513 күн бұрын
Is there a Nu correlation that corresponds to free convection inside a vertical cylinder? why isn't it found in the heat transfer books?
@EngineeringHack10 күн бұрын
If your cylinder has thin walls, then you can just do Q = 2xQ of outside. If it is a solid cylinder, then only outside matters (since it is area-related). If it has thick walls, then you can calculate the nusselt twice (one for the outside wall, and one for the inside) just like in the video but changing the characteristic length. The only situation in which the Nu correlations from the book cannot be used, is when you have a void small enough in which the boundary layer of one part of the wall interacts with another part. Then you can use FEA
@tonykaram47357 күн бұрын
@@EngineeringHack Thank you for the prompt and valuable reply. Just a couple of more clarifications if that’s OK: 1- My cylinder has relatively thick walls, so the Nusselt number corresponding to the inside part of the cylinder should be computed. In this case, the characteristic length would be the pipe diameter (instead of the length), right? In this case, the Gr number in the condition [ (D/L) >= (35/Gr^0.25)] would be computed based on what characteristic length. 2- From what I understood from the video, in case the (D/L) >= (35/Gr^0.25) is not met, I should account for the flat horizontal plate. In my case, the top and bottom covers of the cylinder are adiabatic surfaces (my fluid is actually enclosed in a vertical cylinder with perfectly insulated top and bottom plates). So I need not worry whether this condition is met or not, right? 3- My cylinder diameter is around 95 mm with a length of 5 m. So the issue related to having “a void small enough in which the boundary layer of one part of the wall interacts with another part” could be applicable? How do I know if it is indeed applicable, because I would like to avoid Finite Element Analysis ☹. Kindly clarify 🙏.
@kylecatman773820 күн бұрын
I get why we use h and not u for the incoming air, because the flow work to compress the initial air. BUT, do you use h for the incoming air if the tank is evacuated?
@EngineeringHack16 күн бұрын
You have flow energy, and a mass flow rate. So you need to account for that. Recall that h = u +/- PdV
@EngineeringHack16 күн бұрын
This video might help kzbin.info/www/bejne/o4DWdppolqiGkK8si=z5a182mqVt8a6kW0
@ObinnaEmmanuel-iu9vrАй бұрын
Why blurry
@EngineeringHackАй бұрын
Not sure. At what time stamp is it blurry? Haven't seen it
@milurry3751Ай бұрын
Why didnt we use 0.62 for k instead of 61.7 for finding h?
@EngineeringHackАй бұрын
Because we are using the dt/dx for aluminum. It wouldn't make sense to pair the k for water with the gradient for the aluminum. Also note, the h calculated there is related to the heat transfer as we go from conduction to convection. After the water molecules are carrying the energy (i.e., away from the boundary layer), the h will be different and based on the k of water
@zuzilesphumelele97662 ай бұрын
sir can you please show where you take the enthalpies and entropies
@EngineeringHack2 ай бұрын
Check out the more recent videos on thermodynamics. There is always a link to the property tables in the video description. It is the same tables that were used here
@Uzama553 ай бұрын
Great work thank you, one thing, at the very last step, you said convert to kelvin but you wrote it in Celsius?
@EngineeringHack3 ай бұрын
I wrote both. It is the same for both units as it is a difference (delta) in temperature
@kieranzinn38433 ай бұрын
At 9:50 you said V2 = 4.86V1. Shouldn't it be the other way round? Because earlier you said that V1 = 4.86V2.
@EngineeringHack3 ай бұрын
Yes. You are spot on As a matter of fact, the math only works out if the 4.86 is in the bottom, dividing. Thanks for flagging, I'll update. Final numbers are correct though, I flipped during the presentation but kept the values I got when solving on my own
@kieranzinn38433 ай бұрын
@@EngineeringHack No stress, just wanted to make sure I didn't mess up somewhere. Really appreciate your videos! They help a lot.
@EngineeringHack2 ай бұрын
kzbin.info/www/bejne/pnPRpJ-madyBopI Thanks, mate
@TANTIBEN3 ай бұрын
Do you have the copy of the reference book sir?
@EngineeringHack3 ай бұрын
Yes, it is dynamics by beer, Johnson, Cornwell and Self
@TANTIBEN3 ай бұрын
Thx sm
@naufal65603 ай бұрын
sir how does you get 64? i got 200W in my calculator
@EngineeringHack3 ай бұрын
Not sure if you are asking about the power or the temperature. The power is in W, but it is 65. The temperature is 64 but is in C. Please clarify and I'll look into it for you
@gooddeedsleadto74993 ай бұрын
Could u explain how u found x?
@EngineeringHack3 ай бұрын
Sure. It is explained in detail @08:00 Any specific question?
@victorcamara21553 ай бұрын
Thanks for the video! I'm wondering if you do any tutoring for Dynamics?
@EngineeringHack3 ай бұрын
Not anymore, mate. What are you needing help with?
@user-nw8vv9lc8i4 ай бұрын
Thanks for you videos, you explain these solutions very well!
@EngineeringHack4 ай бұрын
Thank you. I do my best. I appreciate you taking the time to comment.
@emmaolawale46954 ай бұрын
Nice work sir,this really helped me thank you sir
@EngineeringHack4 ай бұрын
I'm glad it helped. Thanks for taking the time to comment
@nawafalshuraya48334 ай бұрын
how did you solve for V1 , you dont have the mass, and its an gas cycle so its not in the tables
@EngineeringHack4 ай бұрын
It is in the table, it just won't be a steam table. You'll look for a table that is only dependent on temperature and has Pr and Vr among others. Note this is not pressure and volume but proxies that are only temperature dependent
@ChadRamseychadr8154 ай бұрын
volume all the way up and i still can't hear
@EngineeringHack4 ай бұрын
Sorry mate. This is a live recording of the class. New videos are hopefully better. I can record these again later
@elijahwalker3235 ай бұрын
way better than Chegg or any of those homework sites that charge you than have the wrong answer or problems in the explanation.
@EngineeringHack5 ай бұрын
Thanks. Yeah, I'm not a fan of Chegg. Often incorrect and students have to unlearn something wrong to then learn it correctly...
@talkinenglish83595 ай бұрын
Thanks sir
@EngineeringHack5 ай бұрын
You are welcome. I'm glad it helped
@Naveenbabuborugadda5 ай бұрын
That really helpful what about p and and 1/V curve?
@EngineeringHack5 ай бұрын
Pressure and volume or power and voltage? :)
@Naveenbabuborugadda5 ай бұрын
@@EngineeringHack pressure and volume
@cosmosatrosanguineus31715 ай бұрын
what is the name of the reference book please?
@EngineeringHack5 ай бұрын
It's dynamics by beer, Johnson, Cornwell and Self
@cosmosatrosanguineus31715 ай бұрын
@@EngineeringHack may i ask what chapter is this please, im not familiar with the book
@littlerabbit78575 ай бұрын
I love you prof.
@littlerabbit78575 ай бұрын
It's clear
@EngineeringHack5 ай бұрын
Thanks for commenting 😊
@rumabose67235 ай бұрын
Let the two no. be x and y X + Y = 1000.......(1) X = 950 + Y..........(2) Substituting eq 2 in 1 950 + Y + Y = 1000 2Y = 50 Y = 50/2 Y = 25 X = 25+950 X = 975
@EngineeringHack5 ай бұрын
Right on
@kyrixx.5 ай бұрын
literally got 25 in my head ☝️🤓
@EngineeringHack5 ай бұрын
Wow! Rare exception!
@gadnuk71595 ай бұрын
X + y = 1000 X = y + 950 X = 975 Y = 25
@EngineeringHack5 ай бұрын
Perfect. That is your brains system 2 though :)
@user-nx3hj3ll3y5 ай бұрын
great video sir
@EngineeringHack5 ай бұрын
So nice of you
@user-zv4ko3fo2q5 ай бұрын
Sooo gooddddd👏🏻👏🏻👏🏻👏🏻👏🏻
@EngineeringHack5 ай бұрын
Thanks for commenting. Hope it is helpful
@WeniSaputri-xh4zd5 ай бұрын
What’s the name of the textbook sir?
@EngineeringHack5 ай бұрын
Yunus A. Cengel & Michael A. Boles
@Prasad123416 ай бұрын
Are you a student or a teacher
@EngineeringHack6 ай бұрын
Both :) A teacher never stops being a student m.kzbin.info/www/bejne/gXqtkGChrMqDgpo
@Prasad123416 ай бұрын
Good work🎉 keep uploading content
@EngineeringHack6 ай бұрын
Thanks
@TheSakuraAnime6 ай бұрын
How can you solve a. without using the table if it's possible?
@EngineeringHack6 ай бұрын
No... The question clearly states: "Taking into account the variation of specific heats with temperature" So you need to use a table. HOWEVER, if that wasn't the case, and knowing air can be treated as an ideal gas in most situations, you could use the specific heat and solve it without a table.
@user-kf2zt2co7v6 ай бұрын
For the last part of finding the temperature, how am I supposed to go about it if my superheated steam table ends at 320.74°C ???
@EngineeringHack6 ай бұрын
Two possibilities: either you grab another table (another source) that does have the temperature range you need, or you extrapolate. There is a video in the channel which I show that case. Let me see if I can find it
@EngineeringHack6 ай бұрын
Check the case of Freon here kzbin.info/www/bejne/fYGXZKZ-r9SeiK8si=UqnR-ErsCqKh7dIL You can take the 15K delta and the 30k delta and extrapolate for things higher than 30k. The farther from 30K, the worst your estimate
@hodaatia51886 ай бұрын
Can you tell me what's the name of book which I can get this problem in it
@EngineeringHack6 ай бұрын
Yep. It's dynamics by beer, Johnson, Cornwell and Self
@brittone25717 ай бұрын
this is the only video i can find that explained the iteration method for heat transfer. thank you!
@EngineeringHack7 ай бұрын
Glad it was helpful! Thanks for taking the time to comment
@nikovriniotis86117 ай бұрын
Very clear explanation and informative. Thanks for the help
@EngineeringHack7 ай бұрын
You're welcome! thanks for commenting :)
@davidorji42247 ай бұрын
This video helped a lot. Although, your first interpolation gave a value that's bigger than the two parent values so...I think you should check it again
@EngineeringHack7 ай бұрын
Thanks for your comment. Which interpolation? The enthalpy of 562.26?
@davidorji42247 ай бұрын
Yes. Nevermind, actually. The values are fine. Just realized you were interpolating for h, not T
@Fernando-np9kb7 ай бұрын
hard to find vids on this stuff, thank you
@EngineeringHack7 ай бұрын
Glad you like them! 😊
@muhammadfuad31627 ай бұрын
Formula h2s is wrong
@pablor12787 ай бұрын
Really? How so?
@EngineeringHack7 ай бұрын
I checked and I don't think it is :) But if you care to expand on why you think that, I can look into you.
@EngineeringHack7 ай бұрын
This is from the university material provided to the students. Some questions come from Yunus' thermodynamics book
@ElifToramandaily8 ай бұрын
Why did you write characteristic length in denomimator at 13.50?
@EngineeringHack7 ай бұрын
Because we are solving for k, not for Sh
@chuhanzhang32758 ай бұрын
what is the name of this material ? is that a book?
@EngineeringHack7 ай бұрын
Yep. This is from Cengel and Yunus
@Mick-qq1pi8 ай бұрын
Explained well, easy to follow with all methods, Thank you.
@EngineeringHack7 ай бұрын
You are welcome. Thanks for the comment ☺️
@yigitcan8248 ай бұрын
Professor I have a question here , in the solution of the book molar mass of oxygen was found.I did not understand why it is found but not used.Could you help me to clear up my confusion here
@EngineeringHack7 ай бұрын
You need the molar weight if you use the ideal gas constant (R) in its general form (i.e., per mol). You'd then use the molar weight to convert the R into the specific R for oxygen. Because in our case we grabbed the specific R directly from the table, we were able to skip this step. Hope this helps. Happy studying
@flyx63238 ай бұрын
Quality video, thank you!
@EngineeringHack8 ай бұрын
Glad you enjoyed it! Thanks for commenting
@nicholasandra15539 ай бұрын
Makasih om
@user-me4wt5uz9f9 ай бұрын
do you have mabey a solution to example like this one?: A cylinder covered with a piston, stopped by brake (piston mass is neglectable). The cylinder contains steam (water) at a pressure of 10 bar and a temperature of 260 degrees Celsius. The whole system is in a big room, and the pressure is 3 bar. Then the brake is removed and the piston moves until the system is stable. a. calculate the final temperature of the steam. b. is the process is reversible? explain
@EngineeringHack9 ай бұрын
Yep. Check the UNSW question playlist and there are questions just like that
@alifarahmandi96849 ай бұрын
Thank you very much sir❤
@EngineeringHack9 ай бұрын
So nice of you
@yigitcan8249 ай бұрын
Professor how in state the pressure is 300 kPa ,can you explain me
@EngineeringHack9 ай бұрын
In which state? Problem statement says it is 300kPa...
@yigitcan8249 ай бұрын
State 3, I meant
@EngineeringHack9 ай бұрын
@@yigitcan824 State 3 is also 300kPa because of the quasi-equilibrium situation we find when we have these frictionless pistons. A more comprehensive explanation can be found here kzbin.info/www/bejne/n6C8i3enhbdkeNEsi=ai9-E5iYSM2kngog&t=63
@animalfarm74679 ай бұрын
I enjoyed the problem but didn't get the same answer. May I respectfully suggest you recheck d2r/dt2; I believe you may have forgotten "n" in the nx^(n-1). Maybe it should be (-2)*(0.25)/((4+t)^3)?
@EngineeringHack9 ай бұрын
I can surely check. What did you get fro your answers?
@animalfarm74679 ай бұрын
@@EngineeringHack Giving you my answer so you can compare it to the textbook answer isn't going to confirm the calculus error. Understand this method of error evaluation is indeterminate, as I could have made an algebraic error from that point on-wards. The most effective way to see the error is if I directly show you the mistake. Reviewing your working from the 6.00 minute mark forward: You started with r(t)=(250/(t+4)) - agreed. You correctly calculated the radial velocity: r ̇(t)=((-250)/(t+4)^2 ) - agreed. Then when you calculated the radial acceleration: r ̈ (t)=d2r/dt2=d/dt {(-250/(t+4)^2 )}, you forgot the (-2) from the (-2)(-250)(t+4)^(-3) That is: d/dt {(-250/(t+4)^2 ) = d/dt {(-250*(t+4)^(-2)) =(-2)*(-250)*(t+4)^(-3) = (+500)*(t+4)^(-3) = (+500)/(t+4)^3, not (+250)/(t+4)^3. Hope this helps.