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In physics and engineering, heat flux or thermal flux, sometimes also referred to as heat flux density [1], 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/m 2). It has both a direction and a magnitude, and so it is a vector quantity.
On-site heat flux measurements are often focused on testing the thermal transport properties of for example pipes, tanks, ovens and boilers, by calculating the heat flux q or the apparent thermal conductivity. The real-time energy gain or loss is measured under pseudo steady state-conditions with minimal disturbance by a heat flux transducer ...
However, one needs to select if the heat flux is based on the pipe inner or the outer diameter. If the heat flux is based on the inner diameter of the pipe, and if the pipe wall is thin compared to this diameter, the curvature of the wall has a negligible effect on heat transfer. In this case, the pipe wall can be approximated as a flat plane ...
The convective heat transfer between a uniformly heated wall and the working fluid is described by Newton's law of cooling: = where represents the heat flux, represents the proportionally constant called the heat transfer coefficient, represents the wall temperature and represents the fluid temperature.
A heat flux sensor is a transducer that generates an electrical signal proportional to the total heat rate applied to the surface of the sensor. The measured heat rate is divided by the surface area of the sensor to determine the heat flux. Silicon encased heat flux sensor for measurements on rugged surfaces
The rate of heat flow is the amount of heat that is transferred per unit of time in some material, usually measured in watts (joules per second). Heat is the flow of thermal energy driven by thermal non-equilibrium, so the term 'heat flow' is a redundancy (i.e. a pleonasm). Heat must not be confused with stored thermal energy, and moving a hot ...
A 2008 review paper written by Philips researcher Clemens J. M. Lasance notes that: "Although there is an analogy between heat flow by conduction (Fourier's law) and the flow of an electric current (Ohm’s law), the corresponding physical properties of thermal conductivity and electrical conductivity conspire to make the behavior of heat flow ...
For a uniform wall heating flux, the modified Rayleigh number is defined as: ... q″ o is the uniform surface heat flux; k is the thermal conductivity. [7] Other ...