Rate equations, resistance networks and the core dimensionless groups used throughout HT A326.
Rate equation
Resistance network
Dimensionless groups
Re
ρVL/μ
ρVL/μ
Pr
ν/α = cpμ/k
ν/α = cpμ/k
Nu
hL/kf
hL/kf
Bi
hLc/ks
hLc/ks
Fo
αt/Lc²
αt/Lc²
Gr/Ra
gβΔTL³/ν² · Pr
gβΔTL³/ν² · Pr
Sh/Sc
hmL/DAB · ν/DAB
hmL/DAB · ν/DAB
1D steady conduction, composite walls, heat generation, and critical insulation radius.
Wall/shell conduction
Composite plane wall
Layers as L:k pairs, e.g. 0.02:0.8,0.05:15,0.01:0.2
Generation and critical radius
Uniform cross-section fin: adiabatic tip, infinite fin, and corrected length approximation.
Lumped capacitance, one-term approximations and semi-infinite constant-surface-temperature response.
Lumped capacitance
One-term centreline estimate
Semi-infinite solid
Forced external, internal and free-convection calculators. Use properties at the film or bulk mean temperature as applicable.
External forced convection
Internal tube flow
Free convection
LMTD, ε-NTU and cylindrical overall-U calculations.
LMTD
ε-NTU
Tube overall U
Blackbody laws, gray diffuse surface exchange and radiation shields.
Two gray surfaces
Fick diffusion and convective mass transfer analogues.
Pool boiling CHF and laminar film condensation helpers.
CHF
Film condensation vertical plate
Shape-factor heat transfer and a compact finite-difference Laplace solver with fixed boundary temperatures.
Shape factor
FD plate
Build a composite heat transfer system. Select geometry, add elements from the toolbar at the bottom, fill in known values, then Solve. Unknown values are computed where possible.
💧 Int. Fluid
⊥ Int. Fins
▤ Layer
⊥ Ext. Fins
🌊 Ext. Fluid
☀ Radiation