Correct Answer - Option 1 : constant pressure
Explanation:
In a reversible constant pressure process, the heat input is the change in enthalpy.
According to the first law of thermodynamics:
δQ = δW + ΔU
For isobaric Process: δW = PdV = P(V2 – V1)
Heat, δQ = δW + ΔU = mcpΔT = dh
So, heat added at constant pressure is equal to change in Enthalpy and it not only increases the temperature (i.e. internal energy) but also does the work.
Non-Flow Processes
- These are compression and expansion processes on gases in a cylinder with complete leak proof. In these, there is only energy transfer with zero mass transfer.
- These nonflow processes can be the followings:
- constant pressure process
- constant volume process
- constant temperature process
- reversible adiabatic process
- poly-tropic process
- constant internal energy process
Isochoric process means volume is constant while all other variables change.
As volume is kept constant therefore no work is done on or by the gas.
Heat absorbed by the gas is completely used to change its internal energy and its temperature.
From First law of Thermodynamics
δQ = ΔU + δW ⇒ δQ = ΔU
so, heat added at constant volume is equal to change in internal energy.
