What is Helmholtz free energy?
Helmholtz free energy in thermodynamics is a thermodynamic potential which is used to measure the work of a closed system with constant temperature and volume. It can be defined in the form of the following equation:\(\large F=U-TS\)
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
Formula development for laws of thermodynamics:\(dU=\delta Q+\delta W\) (first law of thermodynamics for closed system) \(dU=TdS-pdV\) (𝜹Q = TdS and 𝜹W = pdV) \(dU=d(TS)-SdT-pdV\) (product rule ie; d(TS) = TdS+SdT) \(d(U-TS)= -SdT-pdV\) \(dF=-SdT-pdV\) (from F=U-TS)
Application of Helmholtz free energy
- In equation of state: Pure fluids with high accuracy (like industrial refrigerants) are represented using Helmholtz function as a sum of ideal gas and residual terms.
- In autoencoder: Autoencoder is an artificial neural network which is used to encode efficient data. Here Helmholtz energy is used to find the sum of code cost and reconstructed code.
Stay tuned with BYJU’S to know more on other laws from Physics concepts.