CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   What is specific heat really means (http://www.cfd-online.com/Forums/main/116438-what-specific-heat-really-means.html)

mouli1991 April 19, 2013 00:27

What is specific heat really means
 
I have confusion from my school days that why there is specific for everything..like specific heat,temp etc..pls help me with really meaning

immortality April 19, 2013 02:48

a wisely question.
Well,i think maybe several reasons be in existence each different in different cases.
I have not heard specific temperature(in real gas theory?)
But in some cases we want only dimensionless numbers so that probably simplifies our work during calculation or make it easier when do experiments or compare related cases,like specific length that can be the ratio of two lengths.
Or a quantity in a period of time or divided by a quantity of mass,like specific heat(J/kg.K).
In some cases maybe we only want a name for a concept.as an example specific volume is only reciprocal of density.
Want anyone contribute in this argument or my speech is complete?
;)

mouli1991 April 19, 2013 05:09

Oh yeah..yes
 
However I still cant understand...You said some used for concept sake..your example is j/kg k..and why do we need to do that...like specific volume.

RodriguezFatz April 19, 2013 06:22

You can have an amount of heat Q stored inside a block of 2.3kg metal. Now, proportional to this heat Q is the heat capacity of the 2.3kg block C~Q. But this is just the heat capacity of a 2.3kg block. If you want to know the ability of that metal to store heat, you divide C by the mass of the block. Than you get the specific heat capacity. This is a material's property an not any longer the property of any special sized block. So if you are interested in material properties you need these "specific" values.
I guess you can use this explanation for most of the "specific ..." cases.

mouli1991 April 19, 2013 07:42

Yes now explain specific volume.is the sa
me concept as specific heat
..specific volume also material properties

RodriguezFatz April 19, 2013 07:49

Sure... volume of a 0.1m cube of water is 1e-3m^3 or just 1 liter. The mass is about 1 kg. The materials property is volume per mass = specific volume. It's always the same value for water, whether you take any cube, sphere or whatever.

mouli1991 April 19, 2013 09:21

So to find the capacity of 1 cubic volume of liquid to store is specific volume...like ah ...heat storing capacity of a metal..volume/mass
Am I got it correctly..

immortality April 19, 2013 10:08

well always its not related to property of a material.
like specific enthalpy is enthalpy per mass flow rate of fluid(1kg/s for example) or specific work(specific work=work/m_dot)that is related to flow of fluid(enthalpy that 1kg of a fluid transfers in 1 second or work 1kg of a fluid does or is done on it in 1s) not the material.but in overall it is correct.
totally can say when we want to know how much a quantity we have per length,mass or mass flow rate we use the expression of specific xxx.;)

mouli1991 April 19, 2013 10:39

Yep I got that...thank you..specific always to measure quantity and capability of what we take..that's so specific explanation


All times are GMT -4. The time now is 01:15.