Heat Transfer Lecture Notes 1-3

These flashcards cover fundamental concepts and definitions related to heat transfer as discussed in the lecture.

Heat Transfer

The movement of thermal energy from one physical system to another due to temperature difference.

Conduction

The transfer of energy through a substance due to interactions between particles, typically occurring in solids.

Convection

The transfer of heat between a surface and a moving fluid, which can occur in fluids such as liquids and gases.

Radiation

The transfer of heat through electromagnetic waves, allowing heat transfer through a vacuum.

Thermal Conductivity (k)

The rate of heat transfer through a unit thickness of the material per unit area per unit temperature difference.

Specific Heat

The energy required to raise the temperature of a unit mass of a substance by one degree.

First Law of Thermodynamics

Energy can neither be created nor destroyed during a process; it can only change forms.

Energy Balance

The net change in total energy of the system is equal to the difference between total energy entering and leaving the system.

Mass Balance

Mass, like energy, is a conserved property that cannot be created or destroyed during a process.

Fourier's Law

States that the heat transfer rate (q) is proportional to the negative of the temperature gradient.

Heat Transfer

The movement of thermal energy from one physical system to another due to temperature difference.

Conduction

The transfer of energy through a substance due to interactions between particles, typically occurring in solids.

Convection

The transfer of heat between a surface and a moving fluid, which can occur in fluids such as liquids and gases.

Radiation

The transfer of heat through electromagnetic waves, allowing heat transfer through a vacuum.

Thermal Conductivity (k)

The rate of heat transfer through a unit thickness of the material per unit area per unit temperature difference.

Specific Heat

The energy required to raise the temperature of a unit mass of a substance by one degree.

First Law of Thermodynamics

Energy can neither be created nor destroyed during a process; it can only change forms.

Energy Balance

The net change in total energy of the system is equal to the difference between total energy entering and leaving the system.

Mass Balance

Mass, like energy, is a conserved property that cannot be created or destroyed during a process.

Fourier's Law

States that the heat transfer rate (q) is proportional to the negative of the temperature gradient.

Fourier's Law Formula (Heat Flux)

The formula for one-dimensional heat flux (qx) by conduction is: qx = -k \frac{dT}{dx} where k is thermal conductivity (W/(m \cdot K)) and \frac{dT}{dx} is the temperature gradient (K/m).

Heat Conduction through a Plane Wall Formula

The steady-state heat transfer rate (\dot{Q}) through a plane wall due to conduction is given by: \dot{Q} = k A \frac{\Delta T}{L} where k is thermal conductivity, A is the cross-sectional area, L is the wall thickness, and \Delta T is the temperature difference across the wall (T{hot} - T{cold}).

Heat Transfer Formula (Specific Heat)

The amount of heat (Q) absorbed or released by a substance during a temperature change is calculated by: Q = mc\Delta T where m is the mass of the substance (kg), c is its specific heat (J/(kg \cdot K)), and \Delta T is the change in temperature (K or ^{\circ}C).

First Law of Thermodynamics Formula (Closed System)

For a closed system, the energy balance, representing the First Law of Thermodynamics, is expressed as: \Delta U = Q - W where \Delta U is the change in internal energy of the system, Q is the net heat transfer into the system, and W is the net work done by the system.