Critical Heat Flux Calculator

Formula

The formula to calculate the Critical Heat Flux (CHF) is:

\[ \text{CHF} = \frac{C \cdot L \cdot \rho_l \cdot \rho_v}{\rho_l - \rho_v} \]

Where:

CHF – The critical heat flux.
C – The critical heat flux constant.
L – The latent heat of vaporization.
ρl – The density of the liquid.
ρv – The density of the vapor.

Definition

Critical Heat Flux (CHF): The maximum heat flux that can be applied to a surface before a transition occurs from nucleate boiling to film boiling. This transition is characterized by a sudden drop in heat transfer efficiency, leading to a rapid increase in surface temperature. CHF is an important parameter in the design and safety analysis of heat exchangers, nuclear reactors, and other systems involving boiling heat transfer. Understanding and predicting CHF is crucial to prevent overheating and potential failure of equipment.

Example

Let's say the critical heat flux constant (C) is 0.13, the latent heat of vaporization (L) is 2260 J/kg, the density of the liquid (ρl) is 1000 kg/m³, and the density of the vapor (ρv) is 0.6 kg/m³. Using the formula:

\[ \text{CHF} = \frac{0.13 \cdot 2260 \cdot 1000 \cdot 0.6}{1000 - 0.6} \approx 0.176 \, \text{W/m²} \]

So, the Critical Heat Flux (CHF) is approximately 0.176 W/m².

Extended information about "Critical-Heat-Flux-CHF-Calculator"

Critical Heat Flux Formula

Formula: \( \text{CHF} = q'' = \frac{h_{fg} \cdot \rho_v \cdot g \cdot (\rho_l - \rho_v)}{\sigma} \)

\( \text{CHF} \): Critical Heat Flux
\( q'' \): Heat Flux
\( h_{fg} \): Latent Heat of Vaporization
\( \rho_v \): Density of Vapor
\( g \): Gravitational Acceleration
\( \rho_l \): Density of Liquid
\( \sigma \): Surface Tension

Example: \( \text{CHF} = \frac{2257 \cdot 0.6 \cdot 9.81 \cdot (1000 - 0.6)}{0.072} \)

Pool Boiling CHF (Critical Heat Flux)

Formula: \( \text{CHF} = q'' = C \cdot \Delta T_{sat}^n \)

\( \text{CHF} \): Critical Heat Flux
\( q'' \): Heat Flux
\( C \): Constant
\( \Delta T_{sat} \): Temperature Difference
\( n \): Exponent

Example: \( \text{CHF} = 0.13 \cdot 30^{1.7} \)

Heat Flux Calculation Formula

Formula: \( q'' = \frac{Q}{A} \)

\( q'' \): Heat Flux
\( Q \): Heat Transfer Rate
\( A \): Area

Example: \( q'' = \frac{500}{2} \)

Heat Flux to Temperature Calculator

Formula: \( q'' = k \cdot \frac{\Delta T}{L} \)

\( q'' \): Heat Flux
\( k \): Thermal Conductivity
\( \Delta T \): Temperature Difference
\( L \): Thickness

Example: \( q'' = 0.5 \cdot \frac{100}{0.01} \)

Flow Boiling Critical Heat Flux

Formula: \( \text{CHF} = q'' = G \cdot h_{fg} \cdot \left( \frac{\rho_v}{\rho_l} \right)^{0.5} \)

\( \text{CHF} \): Critical Heat Flux
\( q'' \): Heat Flux
\( G \): Mass Flux
\( h_{fg} \): Latent Heat of Vaporization
\( \rho_v \): Density of Vapor
\( \rho_l \): Density of Liquid

Example: \( \text{CHF} = 1000 \cdot 2257 \cdot \left( \frac{0.6}{1000} \right)^{0.5} \)

Critical Heat Flux (CHF) Calculator