4 replies to this topic

[sarahx87]

1. hydrogen gas at 60^oC and at a pressure of 1 atm flows along a flat plate at 122m/s. If the plate is at 93oC and 1.22m long. assuming that the critical Reynolds Number is 5x10⁵,determine the following;

i) the thickness of the hydrodynamic and thermal boundary laters at the end of the plate;
ii)The local skin-friction coefficient at the end of the plate;
iii)The average skin-friction coefficient;
iv)The drag force per meter of the plate width;
v) The local convective heat transfer coefficient at the end of the plate;
vi) the average convective heat transfer coefficient;
vii) the heat transfer from the plate to the hydrogen per meter of the width

2. air at 3x10-4 kg/s and 27^oC enters a rectangular duct that is 1m long and 4mm by 16mm on a side. A uniform heat flux of 600W/m2 is imposed on the duct surface. What is the temperature of the air and the duct surface at the outlet?

3. Air at 100kPa and 10^oC flows across a bank tubes 15 rows high and 5 rows deep at velocity of 7m/s measured at a point in the flow before the air enters the tube banks. The surface of the tubes are maintained at 65^oC. The diameter of the tube is 25 mm; there arrangement is aligned so that the spacing in both the normal and parallel directions to the flow is 37.5mm. Calculate the total heat transfer per unit length for the tube bank and the exit air temperature


i need to submit this in no more than 12 hours , could some1 help me?

[ankur2061]

Dear Students,

I wasn't hoping that the situation would come to this, but of late the OP's that I have seen in the student's section of the forum are a cause of concern. Students are posting their homework assignments for somebody to solve on their behalf or asking for keys of problems given in chemical engineering textbooks. When I now think that as one generation older I had to struggle hard to learn things. It was backbreaking work & burning the midnight oil. But when we learned things the hard way, we were appreciative of the effort gone into the learning & the learning stayed with us.

I dread to think what kind of appreciation you all will have for the effort & toil that goes into becoming a good engineer, if everything is served to you on a platter. Frankly speaking, human nature is such that when you get it easy you waste it easy.

I would like to rest my case now & request students to put up some effort in solving their homework assignment before reverting to the forum. This is just not the way to become an engineer.

Regards,
Ankur.

[clarenceyue]

Dear sarahx87,

Take it from me, no one here in this forum will do the homework for you. Period.

I'm sure your heat transfer textbook will have similar examples to the questions you have posted. I'm going to give you a starting point: You can try looking up the classic heat transfer book by Serth or Incropera & Dewitt.

[sarahx87]

i knew it. just new to this forum things. im not wishing to people answer straight to the question, maybe a discussion would help.
but, yeah, im done doing it, and already send the assigmt. anyhow, thanks for taking ur time reading mine. might post other things, so we can help each other understand CHE better??

Dear sarahx87,

Take it from me, no one here in this forum will do the homework for you. Period.

I'm sure your heat transfer textbook will have similar examples to the questions you have posted. I'm going to give you a starting point: You can try looking up the classic heat transfer book by Serth or Incropera & Dewitt.

[rana680]

i started solving ur 1st problem but after 10 mins i saw dat there r actually three problems.....
better try them urself and then ask here for doubts not for complete answers.
HEAT TRANSFER BY J P HOLMAN... all 3 can be solved..