Final control questions on the subject “heat engineering” The purpose and function of the subject. Working parameter. Status parameters. Base words and phrases

6.4-
 
picture Pv - and Ts - diagrams of gas state change in isothermal process 

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- Amount of heat: The amount of heat added to or removed from a system during an isochoric 
process is equal to the change in the internal energy of the system, according to the first law 
of thermodynamics (ΔU = Q - W).
- Enthalpy: The enthalpy of the system remains constant during an isochoric process, since there 
is no change in volume. Enthalpy is defined as the sum of the internal energy of the system 
and the product of the pressure and volume of the system.
- Entropy: The entropy of the system can increase or not change during an isochoric process if 
there is heat transfer into or out of the system. The second law of thermodynamics states that 
the entropy of an isolated system always increases over time. 
In summary, the isochoric process is a thermodynamic process characterized by constant volume, 
zero work done, change in temperature due to the change in internal energy, and represented 
as a vertical line on a PV diagram. The amount of heat added or removed from the system is 
equal to the change in internal energy during an isochoric process, where the enthalpy of the 
system remains constant. 
13. Isobaric process. 
 
Base words and phrases: temperature, diagrams, internal energy, work, amount of heat, 
enthalpy, entropy 
Isobaric process is a thermodynamic process that occurs at a constant pressure. In an isobaric 
process, the pressure of the gas in the system remains constant while the volume can change.
Here are some base words and phrases related to an isobaric process: 
- Temperature: During an isobaric process, if the amount of gas in the system is constant, the 
temperature of the gas will increase or decrease depending on whether heat is added or 
removed from the system.
- Diagrams: Isobaric processes are represented on thermodynamic diagrams such as pressure-
volume (PV) and temperature-entropy (TS) diagrams. On a PV diagram, an isobaric process 
is a horizontal line since there is no change in pressure.
- Internal energy: The change in internal energy during an isobaric process is equal to the work 
done on or by the system and the amount of heat added to or removed from the system.
- Work: During an isobaric process, the work done on or by the system is equal to the product of 
the pressure times the change in volume (W = P * ΔV). Since the pressure is constant, the 
work done on or by the system can be easily calculated.

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- Amount of heat: During an isobaric process, the amount of heat added to or removed from the 
system is equal to the change in the internal energy plus the work done on or by the system 
(Q = ΔU + P * ΔV).
- Enthalpy: The enthalpy change of the system during an isobaric process is equal to the amount 
of heat added or removed from the system. Enthalpy is defined as the sum of the internal 
energy of the system and the product of the pressure and volume (H = U + P * V).
- Entropy: The entropy of the system can increase or remain constant during an isobaric process if 
there is heat transfer into or out of the system. The second law of thermodynamics states that 
the entropy of an isolated system always increases over time.
In summary, an isobaric process is a thermodynamic process that occurs at constant pressure with 
the change in volume, temperature, internal energy, work, amount of heat, enthalpy, and 
entropy. During an isobaric process, the pressure remains constant, and the amount of heat 
added or removed from the system is equal to the change in the internal energy plus the work 
done on or by the system. The enthalpy change of the system during an isobaric process is 
equal to the amount of heat added or removed from the system.