Thermodynamics

Overview

Engineering reference data for Thermodynamics in miscellaneous.

Key Formulas

Unit Conversion

$y = x \cdot k$

Multiply by conversion factor.

Linear Interpolation

$y = y_1 + \frac{(x - x_1)(y_2 - y_1)}{x_2 - x_1}$

Estimate between two known points.

Percentage

$p = \frac{\text{part}}{\text{whole}} \times 100\%$

Part as fraction of whole.

Variables

Symbol	Description	Unit
$x$	Input value	—
$y$	Output value	—
$k$	Conversion factor	—

Common Thermodynamic Formulas

Several fundamental formulas are essential for engineering calculations beyond the core laws:

Ideal Gas Law: $PV = nRT$ Where P is pressure, V is volume, n is the amount of substance, R is the universal gas constant, and T is absolute temperature.

Fourier's Law of Heat Conduction: $\dot{Q} = -kA \frac{dT}{dx}$ Where $\dot{Q}$ is the heat transfer rate, $k$ is the thermal conductivity, $A$ is the cross-sectional area, and $dT/dx$ is the temperature gradient.

Carnot Efficiency (theoretical maximum for a heat engine): $\eta_{\text{Carnot}} = 1 - \frac{T_C}{T_H}$ Where $T_H$ and $T_C$ are the absolute temperatures of the hot and cold reservoirs, respectively.

Key Definitions

1st Law of Thermodynamics (Conservation of Energy): Energy cannot be created or destroyed, only converted from one form to another. This implies the total energy of an isolated system is constant.

2nd Law of Thermodynamics: Introduces the concept of entropy ($S$). For any spontaneous process, the total entropy of the universe increases. This law governs the direction of processes and sets limits on the efficiency of energy conversion.

Emissivity ($\epsilon$): A material's ability to emit absorbed energy as thermal radiation, compared to a perfect black body ($\epsilon = 1$). It is a dimensionless factor between 0 and 1.

Material Properties Reference

The following table summarizes property ranges for commonly referenced fluids from the source data.

References

• Original Source