Hi Mighty mechs

This is vijay a mechanical engineer
My main intention is to create this blog for those people who are interesting in mechanical subjects and
those who wants to share their views and doubts about any mechanical subjects.......

Monday, October 17, 2011

properties of a system

The thermodynamic properties of a system is basically divided into two general clases

1)Extensive Property:
the property of a system whose value for the entire system is equal to the sum of their values for the individual parts of the system are called extensive properties

ex:Total volume ,total mass,Total energy

Intensive property :

The property of a system (like temperature density ,pressure )is not equal to the sum of their individual parts of the system are called intensive properties

centigrade to fahrenheit or fahrenheit to centigrade

The relation between celsius scale and fahrenheit scale is given by


C/100 = F-32/180

or

C/5=F-32/9

Enthalpy Definition

enthalpy is an thermodynamic property .It can be used to calculate the heat transfer during a Quasi static process taking place in a closed thermodynamic system under constant pressure


In thermodynamics "The sum of internal energy(U) and the product of pressure and volume (pv)is termed as enthalpy
It denoted as H

H=U+pv

For better explanation
watch the below video link


http://www.youtube.com/watch?v=fucyI7Ouj2c

Quasi static process

a quasistatic process is a thermodynamic process that happens infinitely slowly. However, it is very important of note that no real process is quasistatic

Any reversible process is necessarily a quasistatic one.
However, some quasisatic processes are irreversible,

Latent Heat

Heat that causes a change of state with no change in temperature is called latent heat.

example, water remains at 100°C while boiling

Sensible heat

Sensible heat
When an object is heated, its temperature rises as heat is added. The increase in heat is called sensible heat.
Similarly,
when heat is removed from an object and its temperature falls, the heat removed is also called sensible heat.
Heat that causes a change in temperature in an object is called sensible heat.
What is the difference between sensible and latent heat

Entropy

it is a function of a quantity of heat which shows the possibiliy of conversion of that heat into work



Entropy is a thermodynamic property that can be used to determine the energy available for useful work in athermodynamic process, such as in energy conversion devices, engines, or machines