The key difference between adiabatic and reversible adiabatic process is that in adiabatic processes, the adiabatic system is insulated and does not allow any heat transfers, whereas reversible adiabatic process involves heat transfer in which the quantity of heat transferred is directly proportional to the entropy change of the system.
Adiabatic processes are thermodynamic processes in which no net heat transfer occurs due to reaction conditions. Reversible adiabatic process also does not involve a heat transfer. Here, the heat transferred is directly proportional to the entropy change of the system, and the entropy change is zero, which in turn makes the heat transfer zero.
CONTENTS
1. Overview and Key Difference
2. What is Adiabatic Process
3. What is Reversible Adiabatic Process (Isentropic Process)
4. Adiabatic vs Reversible Adiabatic Process in Tabular Form
5. Summary – Adiabatic vs Reversible Adiabatic Process
What is Adiabatic Process?
Adiabatic process can be defined as a change of a system in which no heat is transferred into or out of the system. Mainly, the heat transfer is stopped in two ways. One method involves using a thermally insulated boundary so that no heat can enter or exit. For example, a reaction that occurs in a Dewar flask is adiabatic. Another method an adiabatic process can take place is when a process takes place very rapidly; thus, there is no time left to transfer heat in and out.
In thermodynamics, we show the adiabatic changes by dQ=0. In these instances, there is a relationship between pressure and temperature. Therefore, the system undergoes changes due to pressure in adiabatic conditions. This is what happens in cloud formation and large-scale convectional currents. At higher altitudes, there is lower atmospheric pressure. When air heats up, it tends to go up. Because the outside air pressure is low, the rising air parcel will try to expand. When expanding, the air molecules do work, and this will affect their temperature. This is why the temperature reduces when rising up.
According to thermodynamics, the energy in the parcel remains constant, but it can be converted to do the expansion work or to maintain its temperature. There is no heat exchange with the outside. This same phenomenon applies to air compression, too (e.g., a piston). In that situation, when the air parcel compresses, temperature increases. These processes are called adiabatic heating and cooling.
What is Reversible Adiabatic Process (Isentropic Process)?
A reversible adiabatic process is also known as an isentropic process. Spontaneous processes increase the entropy of the universe. When this happens, either the system entropy or the surrounding entropy may increase. An isentropic process happens when the system entropy remains constant. A reversible adiabatic process is an example of an isentropic process. Moreover, the constant parameters in an isentropic process are entropy, equilibrium, and heat energy.
These types of processes are idealized thermodynamic processes that are adiabatic, but the heat transfer is frictionless, which means there is no transfer of heat or matter, and the process is reversible.
What is the Difference Between Adiabatic and Reversible Adiabatic Process?
The adiabatic process can be defined as a change of a system in which no heat is transferred into or out of the system. A reversible adiabatic process is also known as an isentropic process. The key difference between adiabatic and reversible adiabatic process is that in adiabatic processes, the adiabatic system is insulated and does not allow any heat transfers, whereas the reversible adiabatic process involves heat transfer in which the quantity of heat transferred is directly proportional to the entropy change of the system.
The below infographic presents the differences between adiabatic and reversible adiabatic process in tabular form for side by side comparison.
Summary – Adiabatic vs Reversible Adiabatic Process
Adiabatic processes are thermodynamic processes in which no net heat transfer occurs due to the reaction conditions. The key difference between adiabatic and reversible adiabatic process is that in adiabatic processes, the adiabatic system is insulated and does not allow any heat transfers, whereas reversible adiabatic process involves heat transfer in which the quantity of heat transferred is directly proportional to the entropy change of the system.
Reference:
1. “Adiabatic Process – Definition, Equation, Reversible Adiabatic Process, Example, Differences, Video and Faqs.” BYJU’S, 4 Aug. 2021.
Image Courtesy:
1. “Adiabatic” By User:Stannered – Image:Adiabatic.png (CC BY-SA 3.0) via Commons Wikimedia