The heat flux shares a direct relationship with the temperature gradient. Temperature difference - The temperature difference or gradient is necessary for any heat transfer to take place. The heat flux in a system is dependent on: The heat flux is a vector quantity with both magnitude and direction. Heat flux density is measured in SI unit-Watts per square meter (W/m2). Heat flux can be calculated as the heat transfer rate per unit area, otherwise known as the heat flux density. The amount of heat energy transferred, or the heat transfer rate, can be measured in Joule per second or Watt. Since the heat flux is based on these two quantities, it is considered a derived quantity. (Alt text: Generalized heat flux equation) The area where the heat transfer takes place (A) The amount of heat transfer per unit area (Q) Heat flux is evaluated based on two fundamental quantities: Heat flux is also known as thermal flux, heat flow density, heat flux density, or heat flow rate intensity. The heat flux can be the amount of heat transferred from or dissipated on the surface of consideration. Heat flux is the amount of heat energy transferred through a surface in a unit area in unit time. The rate of heat energy transferred gives the idea of heat flux in conduction, convection, and radiation. In the above heat transfer mechanisms, heat is transferred from one point to another through a medium. Radiation - When electromagnetic waves carry heat energy, it forms the radiation mechanism of heat transfer.

Depending on the medium or the set of media where there is a temperature gradient, heat transfer mechanisms can be classified into:Ĭonduction - In conduction, heat flow takes place through solid materials.Ĭonvection - When heat flows through gases and liquids, the heat transfer mechanism is called convection. The heat flow or heat transfer phenomenon is complex and multi-dimensional. Heat flow occurs only if there is a medium for the heat to travel between points with different temperatures. The heat flows from a warmer location to a colder location. In a given system, heat flows from one point to another only if there is a temperature difference between them. Let’s explore heat flux and its equations. However, in practicality, a range of calorimeters, gauges, and radiometers are used. Theoretically, the heat flux equation is utilized for calculating heat flux. In most thermodynamic applications, heat flux is a fundamental quantity of importance, as it influences efficiency and performance. Understanding heat flux aids in determining the efficiency of solar receivers. In the design of concentrated solar power plants, especially solar receivers, heat flux and temperature are two primary design parameters. Concentrated solar power plants meet today’s energy requirements. Solar power is used for utility power generation as well as heating. Among non-conventional energy sources, solar energy is critical due to its abundance. The demand for energy encourages us to explore opportunities in renewable energy sources. The heat flux in a system is dependent on the temperature gradient and heat transfer coefficient.ĭepending on the medium, heat transfer mechanisms are classified into conduction, convection, or radiation The heat flux density is measured in SI unit-Watts per square meter. Heat flux is defined as the amount of heat energy transferred through a surface in a unit area in unit time.

Surface heat flux