Monday, 11 July 2016

WORK ENERGY TRANSFER IN THERMODYNAMICS: PADDLE WHEEL WORK

WORK ENERGY TRANSFER IN THERMODYNAMICS: PADDLE WHEEL WORK

We have seen the basic concepts and also method of calculations of heat energy transfer and work energy transfer in the field of thermal engineering. We have also mentioned in our previous post to see the basic concepts for each type of work transfer in the field of thermal engineering and so we have already seen the “Displacement work or PdV work inthermodynamics”.

Today we will see here another type of work transfer i.e. Paddle wheel work in the field of thermal engineering.

Paddle wheel work or stirrer work

Let we have one container with liquid as displayed here in figure. We can see here the stirrer or paddle wheel which will be rotated mechanically. In order to rotate the stirrer or paddle wheel, we will have to go for lowering the weight as displayed here.

Now we will have one question in our mind, what we want to explain here?

Liquid in container will be considered as the system here and let us assume that initially system is at state 1. As we are observing here that work is being transferred here from surrounding to the system.

Therefore we can say that work is done on the system from the surrounding and hence system will be now at another state say it state 2 due to this work energy transfer.

Temperature of liquid in container will be increased, when stirrer or paddle wheel will be rotated. We must note it here that some other thermodynamic properties might also be changed due to changing in temperature of the system depending on the relationship of respective thermodynamic property with temperature.

We will see flow work transfer and shaft work transfer in our next post in thermodynamics.

Do you have suggestions? Please write in comment box.

Reference:

Engineering thermodynamics by P. K. nag
Engineering thermodynamics by r. k. Rajput
Image courtesy: Google

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