Throttling is an irreversible process where a fluid loses pressure as it passes through a restriction. It occurs in situations like fluid flowing through a partially opened valve, a very small opening, or a porous plug. During throttling, there is negligible work transfer and heat transfer due to the small pressure differences and short device length. As a result, throttling is an isenthalpic process where the enthalpy of the fluid remains constant.

1. Throttling is the process in which a fluid passing
through a restriction loses pressure.

3. Now imagine their are students in a class room and as the bell
rungs they started moving out. Now if the door is opened
partially then their will be clusters form by the students. Similarly
in flow of fluid their is restriction to flow. now as students form
clusters they pushing other students and in the same way fluid
particles start rubbing with other molecules and as a result
friction is their and as we all know friction is one of the biggest
reason for any process to make it irreversible.
Hence it is clear that Throttling is irreversible.

4. 1. Flow through a partially opened valve as in IC engines
2. Flow through a very small opening e.g. orifice.
3. Flow through a porous plug.

6. 1. No Work Transfer
2. No Heat Transfer
3. Irreversible Process
4. Isenthalpic Process

7. Explanation:
As we know their is work transfer in turbines due to
very large pressure difference. but in the case of
throttling their is very low pressure differences so the
work we get is very small and this work is lost in
overcoming friction. so here we generally neglect
the work transfer.

8. Explanation:
Lets see it with a example... imagine you open the freeze and
took out your water bottle and just within the fraction of seconds
you put back that bottle, now what is the temperature difference
between the two states of the water bottle, it is approx. zero. It
means heat transfer needs some time , now what happened in
throttling is that device length is very small and the fluid is always
pushed ahead due to the bulk coming and due this their is not
much time for the heat transfer. As we are considering the steady
flow and bulk is not accumulated in the device so heat transfer is
also neglected.

10. Explanation:
The word ISENTHALPIC means same Enthalpy. Look we apply steady flow
energy equation:
now neglecting potential energy changes and
heat transfer(q) and work transfer (w) are zero as the characteristics of
throttling..
Equation becomes:
now what we generally seen that practically velocities values (c1 and c2 ) are
very very small as compared to enthalpies values so c1 and c2 can be
neglected and finally
Hence the process is Isenthalpic.