The document provides an overview of heat conduction, thermal resistance, overall heat transfer coefficient, and mass transfer. It explains key concepts including heat conduction driven by temperature gradients, the opposition to heat flow represented by thermal resistance, and the comprehensive effect of various transfer modes captured by the overall heat transfer coefficient. Additionally, it emphasizes mass transfer dynamics, applications in real-world contexts, and encourages audience interaction for deeper understanding.

1. Heat Conduction, Thermal
Resistance, Overall Heat Transfer
Coefficient, and Mass Transfer
An Overview
Presented by: Md. Helal Hossain
Department: Mechanical
Engineering, World University of
Bangladesh

2. Heat Conduction Concepts
• - Definition: Heat conduction is the transfer of
thermal energy within a body due to
temperature gradient.
• - Fourier’s Law: q = -kA dT/dx
• - q = Heat transfer rate (W)
• - k = Thermal conductivity (W/m·K)
• - A = Cross-sectional area (m²)
• - dT/dx = Temperature gradient (K/m)

3. Thermal Resistance
• - Definition: Opposition to heat flow through a
material.
• - Thermal Resistance Formula:
• - Conduction: R_cond = L/kA
• - L = Thickness of the material (m)
• - Convection: R_conv = 1/hA
• - h = Convective heat transfer coefficient
(W/m²·K)

4. Overall Heat Transfer Coefficient
• - Definition: Combined effect of conduction,
convection, and radiation in heat transfer.
• - Formula:
• - 1/U = 1/hi + L/k + 1/ho
• - U = Overall heat transfer coefficient
(W/m²·K)
• - hi and ho = Internal and external
convective heat transfer coefficients

5. Mass Transfer
• - Definition: Movement of mass from one
location to another, often occurring in gases
or liquids.
• - Driving Forces: Concentration gradients,
pressure gradients, temperature gradients.
• - Modes of Mass Transfer:
• - Diffusion: Movement from high to low
concentration.

6. Applications and Examples
• - Heat Conduction:
• - Thermal insulation in buildings
• - Cooling of electronic devices
• - Thermal Resistance:
• - Design of thermal insulators
• - Heat sinks in electronics
• - Overall Heat Transfer Coefficient:
• - Designing efficient heat exchangers

7. Summary
• - Key Concepts:
• - Heat conduction is driven by temperature
gradients.
• - Thermal resistance is the opposition to heat
flow.
• - Overall heat transfer coefficient accounts
for combined modes of heat transfer.
• - Mass transfer involves movement due to

8. Q&A
• - Questions and Discussion
• - Encourage audience to ask questions and
discuss real-world applications.
• - Provide further explanations on complex
topics as needed.

9. References
• - Books and Articles:
• - Incropera, F.P., DeWitt, D.P., "Fundamentals
of Heat and Mass Transfer"
• - Cengel, Y.A., "Heat and Mass Transfer:
Fundamentals and Applications"
• - Relevant research papers and articles