Mechanical Engineering - Thermodynamics - Discussion

There is no heat interaction between system and surrounding in adiabatic process.

Temperature will change only in form of work done by system (decrease in temp) , or work done on system (increase in temp).

For example, take an insulated piston cylinder device containing some arbitrary gas (common example in thermodynamics problems). If you were to push the piston down (thus compressing the contents of the cylinder), the temperature of the gas in the cylinder would increase. If the piston was pulled out (thus expanding the gas) the temperature would decrease. In either case, no heat would flow to or from the system, but the temperature would change approximately according to the relationship PV=nRT (for the most general cases).

So that's why this is the right answer.

The internal energy of a ideal gas is function of temperature only. So, if internal energy will change adiabatically then temperature will also change.

U= Function of T only for ideal gas.

Option B is also correct because as we have studied in Air refrigeration system that due to throttling process (due to the friction occurs between container and gas atoms) the heat generated and is absorbed by a gas atom and hence a slight change occurs in the temperature of gas.

That's why the temperature changes occur in the adiabatic process also.

As all the three options are true for the question so the right answer is OPTION:- D.

Here Q=U+w it depends upon the piston moves from bdc to tdc.

In Option B, Temperature of system changes with heat addition or Rejection. How could it possible?

I think the Option A is correct.

Adiabatic process is the process where there is no change in internal energy of the system. Reversible adiabatic process is isentropic process means the amount of work is done is totally converted in heat.

If there is no heat or mass transfer between system and surrounding then all the work done by surrounding is stores as a internal energy and changes in internal energy is means change in temperature.

Hence option D is correct.

Internal energy is a function of temperature so temperature must be change. For more information refer adiabatic free expansion process.