**Are you an EPFL student looking for a semester project?**

Work with us on data science and visualisation projects, and deploy your project as an app on top of GraphSearch.

Lecture# Heat Transfer: Convection and Heat Flux

Description

This lecture focuses on natural convection and the importance of solving exercises to understand derivations and heat transfer. The instructor explains the concept of Nusselt number, which represents the boundary layer and heat flux. By making the heat flux non-dimensional with the Nusselt number, one can determine the amount of energy needed for heat transfer. The lecture delves into predicting the Nusselt number for heating water in a pipe, emphasizing the balance between convection, diffusion, and heat production. Through a detailed analysis of non-dimensional numbers like Reynolds, Peclet, and Nusselt, the lecture illustrates the dominance of conduction in heat transfer processes.

Official source

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related concepts (23)

Convection (heat transfer)

Convection (or convective heat transfer) is the transfer of heat from one place to another due to the movement of fluid. Although often discussed as a distinct method of heat transfer, convective heat transfer involves the combined processes of conduction (heat diffusion) and advection (heat transfer by bulk fluid flow). Convection is usually the dominant form of heat transfer in liquids and gases. Note that this definition of convection is only applicable in Heat transfer and thermodynamic contexts.

Heat

In thermodynamics, heat is the thermal energy transferred between systems due to a temperature difference. In colloquial use, heat sometimes refers to thermal energy itself. An example of formal vs. informal usage may be obtained from the right-hand photo, in which the metal bar is "conducting heat" from its hot end to its cold end, but if the metal bar is considered a thermodynamic system, then the energy flowing within the metal bar is called internal energy, not heat.

Heat transfer

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species (mass transfer in the form of advection), either cold or hot, to achieve heat transfer.

Heat flux

In physics and engineering, heat flux or thermal flux, sometimes also referred to as heat flux density, heat-flow density or heat flow rate intensity, is a flow of energy per unit area per unit time. Its SI units are watts per square metre (W/m2). It has both a direction and a magnitude, and so it is a vector quantity. To define the heat flux at a certain point in space, one takes the limiting case where the size of the surface becomes infinitesimally small.

Heat transfer coefficient

In thermodynamics, the heat transfer coefficient or film coefficient, or film effectiveness, is the proportionality constant between the heat flux and the thermodynamic driving force for the flow of heat (i.e., the temperature difference, ΔT ). It is used in calculating the heat transfer, typically by convection or phase transition between a fluid and a solid. The heat transfer coefficient has SI units in watts per square meter per kelvin (W/m2/K).

Related lectures (157)

Heat Transfer Fundamentals

Explores the fundamentals of heat transfer, including radiation, convection, and conduction, emphasizing boundary layers and Nusselt numbers.

Heat Transfer Fundamentals

Covers the fundamentals of heat transfer, including radiative properties, boundary layer theory, and Prandtl number.

Internal Flows and Boundary LayersME-465: Advanced heat transfer

Explores internal flows, boundary layers, heat transfer coefficients, and Nusselt number correlations in thermal systems.

Heat Transfer FundamentalsME-465: Advanced heat transfer

Covers the fundamentals of heat transfer, focusing on radiation, conduction, and convection, including boundary layers and Nusselt number.

Thermal Bridges in Building TechnologyAR-241: Building technology III

Explores the physics of thermal bridges and heat transfer in building elements, emphasizing energy efficiency.