medium6 marks

Heat Transfer

20 Topics

25h prep

25% subject weight

20 Topics

Modes of heat transfer

Conduction, convection, radiation basics.

1m2/10

📌 Key Formulaq = -k dT/dx, hAΔT, σ ε A (T^4 - T_s^4)

One dimensional heat conduction

Steady state in plane wall, cylinder, sphere.

1m3/10

📌 Key Formulaq = kA ΔT / L

Resistance concept

Analogous to electrical resistance for heat flow.

1m3/10

📌 Key FormulaR_cond = L/kA, R_conv = 1/hA

Electrical analogy

Heat transfer analogous to current flow.

1m3/10

📌 Key Formulaq = ΔT / R_total

Heat transfer through fins

Efficiency and effectiveness of extended surfaces.

1m4/10

📌 Key Formulaη_fin = tanh(mL)/mL

Unsteady heat conduction

Transient temperature distribution.

1m4/10

📌 Key FormulaLumped: T(t) = T∞ + (Ti - T∞) e^{-(hA/ρVc)t}

Lumped parameter system

Uniform temperature assumption when Bi small.

1m3/10

📌 Key FormulaBi = h L_c / k < 0.1

Heisler's charts

Graphical solution for transient conduction in slabs, cylinders, spheres.

1m4/10

📌 Key FormulaMidplane temperature vs Fo, Bi

Thermal boundary layer

Region where temperature gradient exists in convection.

1m4/10

📌 Key Formulaδ_t / δ ≈ Pr^{-1/3}

Dimensionless parameters in free and Forced convective heat transfer

Nu, Pr, Gr, Ra, Re.

1m3/10

📌 Key FormulaNu = hL/k, Ra = Gr Pr

Heat transfer correlations for flow over flat plates and through pipes

Dittus-Boelter, Gnielinski, etc.

2m4/10

📌 Key FormulaNu = 0.023 Re^{0.8} Pr^{0.4} (heating)

Effect of turbulence

Enhanced mixing increases heat transfer.

1m3/10

📌 Key FormulaHigher Nu in turbulent

Heat exchanger performance

Effectiveness, NTU method.

1m4/10

📌 Key Formulaε = q_actual / q_max

LMTD and NTU methods

Log mean temperature difference and number of transfer units.

2m4/10

📌 Key FormulaLMTD = (ΔT1 - ΔT2)/ln(ΔT1/ΔT2)

Radiative heat transfer

Black body, emissivity, view factors.

1m4/10

📌 Key Formulaq = ε σ A (T^4 - Ts^4)

Stefan-Boltzmann law

Blackbody emissive power.

1m3/10

📌 Key FormulaE_b = σ T^4

Wien's displacement law

Wavelength of maximum emission.

1m3/10

📌 Key Formulaλ_max T = 2898 μm K

Black and grey surfaces

Ideal vs real emitters/absorbers.

1m3/10

📌 Key Formulaα = ε for gray

View factors

Fraction of radiation leaving one surface intercepted by another.

1m4/10

📌 Key FormulaF_{12} = A2 F_{21} / A1 reciprocity

Radiation network analysis

Radiosity, irradiation, network for enclosures.

1m5/10

📌 Key FormulaRadiosity J = ε σ T^4 + (1-ε) G

medium6 marks

Heat Transfer

20 Topics

25h prep

25% subject weight

20 Topics

Modes of heat transfer

Conduction, convection, radiation basics.

1m2/10

📌 Key Formulaq = -k dT/dx, hAΔT, σ ε A (T^4 - T_s^4)

One dimensional heat conduction

Steady state in plane wall, cylinder, sphere.

1m3/10

📌 Key Formulaq = kA ΔT / L

Resistance concept

Analogous to electrical resistance for heat flow.

1m3/10

📌 Key FormulaR_cond = L/kA, R_conv = 1/hA

Electrical analogy

Heat transfer analogous to current flow.

1m3/10

📌 Key Formulaq = ΔT / R_total

Heat transfer through fins

Efficiency and effectiveness of extended surfaces.

1m4/10

📌 Key Formulaη_fin = tanh(mL)/mL

Unsteady heat conduction

Transient temperature distribution.

1m4/10

📌 Key FormulaLumped: T(t) = T∞ + (Ti - T∞) e^{-(hA/ρVc)t}

Lumped parameter system

Uniform temperature assumption when Bi small.

1m3/10

📌 Key FormulaBi = h L_c / k < 0.1

Heisler's charts

Graphical solution for transient conduction in slabs, cylinders, spheres.

1m4/10

📌 Key FormulaMidplane temperature vs Fo, Bi

Thermal boundary layer

Region where temperature gradient exists in convection.

1m4/10

📌 Key Formulaδ_t / δ ≈ Pr^{-1/3}

Dimensionless parameters in free and Forced convective heat transfer

Nu, Pr, Gr, Ra, Re.

1m3/10

📌 Key FormulaNu = hL/k, Ra = Gr Pr

Heat transfer correlations for flow over flat plates and through pipes

Dittus-Boelter, Gnielinski, etc.

2m4/10

📌 Key FormulaNu = 0.023 Re^{0.8} Pr^{0.4} (heating)

Effect of turbulence

Enhanced mixing increases heat transfer.

1m3/10

📌 Key FormulaHigher Nu in turbulent

Heat exchanger performance

Effectiveness, NTU method.

1m4/10

📌 Key Formulaε = q_actual / q_max

LMTD and NTU methods

Log mean temperature difference and number of transfer units.

2m4/10

📌 Key FormulaLMTD = (ΔT1 - ΔT2)/ln(ΔT1/ΔT2)

Radiative heat transfer

Black body, emissivity, view factors.

1m4/10

📌 Key Formulaq = ε σ A (T^4 - Ts^4)

Stefan-Boltzmann law

Blackbody emissive power.

1m3/10

📌 Key FormulaE_b = σ T^4

Wien's displacement law

Wavelength of maximum emission.

1m3/10

📌 Key Formulaλ_max T = 2898 μm K

Black and grey surfaces

Ideal vs real emitters/absorbers.

1m3/10

📌 Key Formulaα = ε for gray

View factors

Fraction of radiation leaving one surface intercepted by another.

1m4/10

📌 Key FormulaF_{12} = A2 F_{21} / A1 reciprocity

Radiation network analysis

Radiosity, irradiation, network for enclosures.

1m5/10

📌 Key FormulaRadiosity J = ε σ T^4 + (1-ε) G