In thermodynamics, the Helmholtz free energy is a thermodynamic potential that estimates the useful work available from a closed thermodynamic system at a constant temperature. Let’s look into Helmholtz Energy and how it differs from Gibbs Energy.
What is Helmholtz free energy?
Helmholtz free energy is a concept in thermodynamics where the work of a closed system with constant temperature and volume is measured using thermodynamic potential. It may be described as the following equation:
- F = U -TS
- Where,
- F = Helmholtz free energy in Joules
- U = Internal energy of the system in Joules
- T = Absolute temperature of the surroundings in Kelvin
- S = Entropy of the system in joules per Kelvin
Derivation:
The Helmholtz equation is derived using the law of thermodynamics, so according to 1st law of the thermodynamics
- 𝜹Q = 𝜹W + dU
If the 1st law of thermodynamics is applied to closed systems,
- For the close system
- 𝜹Q = TdS
- 𝜹W = PdV
- ggg
- dU = d(TS) – SdT – PdV
- Note: d(TS) = SdT – TdS
- dU – d(TS) = – (SdT + PdV)
- dF = – (SdT + PdV)
Application of Helmholtz Free Energy
In equation of state:
The Helmholtz function is used to describe pure fluids with great precision as the sum of an ideal gas and residual components, such as industrial refrigerants.
In auto-encoder:
An artificial neural network called an auto-encoder is used to encode data efficiently. The total cost of the original code and the rebuilt code is calculated here using Helmholtz energy.
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