Lecture 02: Introduction and Fundamental Concepts - II

This lecture covers the following topics:
1. Types of heat conduction: Steady, Unsteady, 1D, 2D and 3D
Steady state 1-D heat conduction in plane wall without generation of thermal energy,
2. Introduction to convection heat transfer,
3. Thermal properties of matter: Thermal diffusivity.

[@AbhishekVigyan]

SK Som is the best teacher I've ever seen.

[@khanyusuf09]

greatest professor India has ever seen...He is like issac newton for us engineering student.. his contribution to us is beyond one can conceive

[@santhoshiwillbealegend5282]

i already watched your thermodynamics & fluid mechanics lectures sir, you are simply awesome sir.

[@meneswarreddy4627]

I love your way of teaching sir... from the roots

[@raorajesh9582]

Great explained sir 👌🙏

[@NAYAN-t3e]

• For steady state heat transfer -
1) The rate of internal energy accumulation or storage within the mass or control volume of system at any instant of time is zero.
2) So, the efflux of thermal energy & conversions are mutually balanced at any instant & at every local point in the system.
3) Temperature at any instant of time is independent of time & only function of space variables.
For cartesian - T = T(x,y,z),
For cylindrical - T = T(r, theta, z),
For spherical - T = T(r, theta, phi).
4) System may or may not to be in thermal equilibrium with surroundings even if it is in steady state. Thermal equilibrium is the end state of steady state heat transfer.

[@kumarrohan6186]

Jordar tarike se samajh me aya hai convection. Thank you so much sir.

[@avinashreddy8664]

Down to earth !!

[@sujitkumarmohanta2311]

Thank you sir

[@junaidshafi302]

Sir what is meant by momentum retention and transport and between what

[@ravenship2486]

How convection is not possible in solids. Sir, lets take an example of cloth, cold water and person with fever. We dip cloth in cold water, and then place in on the forehead, then the cloth(solid) takes the heat , then we dip In cold water it become cool. Then again we put that solid wet cloth on forehead hence according to me convection takes place. So tell me, your views regarding this , sk som sir.

[@bhushanpatil9303]

Here we have go into detail of the phenomena that happens. Whenever you dip a cloth in water, water gets absorbed in cloth due to capillary action. Cappilary action is rise of liquid in small holes or capillaries due to surface tension. It is the same phenomena because of which kerosene travels to flame throufh cotton wick in kerosene lamp. So after dipping the cloth in water, it becomes soaked. Then this cloth is put on forehead of person having fever. Here cloth molecules remain intact instead water molecule moves through cloth due to combined effect of evaporation and capillary action. Water molecules from top layer of cloth evaporates leaving space behind. Due to capillary action, this space is occupied by new water molecule. So convection of water is carrying the heat not the solid. Due to complete evaporation of water, after some time cloth becomes dry. Note that here also heat transfer happens from High temperature (Persons forehead) to low tempearure (cold water). Last point to note for convection to happens it is important for molecules to flow or leave their place. Solids have strong bonds hence convection is impossible. Liquid & gases have weak bonds hence can easily flow around.

[@ravenship2486]

@@bhushanpatil9303 I don't mean it. I meant that solid can be cooled after it became hot and can be applied to the forehead again. Then is it possible for solid to transfer heat conventionally?

[@junaidshafi302]

@@ravenship2486 in the first lecture of Prof S.K SOM he has said is very clear that basically Radiation and Conduction are only modes of transfer of heat and convection is dependent on the conduction. and what you are saying is Is it possible for solid to transfer heat convectionally i guess not conventionally in your question well that is what convection is the case you are proposing in that there is air which is a fluid and that moves over the solid body , fluid gets heated and solid body becomes cool due to convection.

[@himanshusrivastava6548]

❤❤❤❤❤

[@hearthacker6415]

👍 👍

[@pvsmouli7727]

sir u said that cold water has ambient temperature at 30:32 but ambient temperature is nothing but the surrounding temperature. so in steam condensors the temperature of water will be less than surrounding air temperature. can anyone clarify my doubt

[@siddharthbhopatrao5861]

pvs Mouli inlet cooling water temperature is same as that of the surrounding temperature and after exchanging heat with the steam its temperature increases at the outlet

[@anupamrawat1151]

can anyone tell me that what was that linear profile whose slope depend upon thermal conductivity at 21:02

[@ravenship2486]

It means temperature depend linearly with distance between two temperature zone (hot and cold). For example, if one side is 100K and other is 900K then at midplane temperature is 500K and at mid of it , it is 300K

[@nasif4690]

@@ravenship2486 how did you calculate 500k and 300k?

[@ravenship2486]

@@nasif4690 I didn't calculate it. I was just explaining linearity. If temperature has linear profile . We can calculate temperature at any distance easily as it is linear y= mc + c.

[@prashantjha6292]

Gate button

[@deeprajyaguru1913]

rip, sir

[@vikasbhat5926]

Thank you sir