Heat transfer is the movement of thermal energy from one object or system to another due to temperature differences. There are three main modes of heat transfer: conduction, convection, and radiation.

Heat Transfer Modes:

• Conduction: Heat transfer through a solid material or between solids in contact
• Convection: Heat transfer between a solid surface and a moving fluid
• Radiation: Heat transfer through electromagnetic waves (no medium required)

Key Formulas:

• Q_cond = kAΔT/d - Conduction heat transfer
• Q_conv = hAΔT - Convection heat transfer
• Q_rad = εσA(T⁴_hot - T⁴_cold) - Radiation heat transfer
• q" = Q/A - Heat flux
• R = d/k - Thermal resistance
• Q_total = Q_cond + Q_conv + Q_rad - Total heat transfer

Material Properties:

• Copper: k = 400 W/m·K, ε = 0.04
• Aluminum: k = 237 W/m·K, ε = 0.05
• Steel: k = 50 W/m·K, ε = 0.8
• Glass: k = 1.4 W/m·K, ε = 0.9
• Wood: k = 0.12 W/m·K, ε = 0.9
• Concrete: k = 1.4 W/m·K, ε = 0.9
• Insulation: k = 0.04 W/m·K, ε = 0.9

Units:

• Heat transfer: Watts (W)
• Heat flux: W/m²
• Thermal conductivity: W/m·K
• Heat transfer coefficient: W/m²·K
• Thermal resistance: m²·K/W
• Temperature: Kelvin (K)

Applications:

• Building insulation and HVAC
• Electronic cooling systems
• Heat exchangers
• Thermal management
• Energy efficiency analysis