Heat Flux Deutsch
Heat Flux Deutsch Beispiele aus dem Internet (nicht von der PONS Redaktion geprüft)
For calculating the heat flux density (intensity) at a certain distance from the surface of the source, it is generally required to consider not only the amount of. Englisch-Deutsch-Übersetzungen für heat flux im Online-Wörterbuch otbdance.co (Deutschwörterbuch). Übersetzung im Kontext von „, heat flux“ in Englisch-Deutsch von Reverso Context: heat flux. Übersetzung im Kontext von „heat flux“ in Englisch-Deutsch von Reverso Context: Change the option to calculate stresses, rotations, or heat flux. Lernen Sie die Übersetzung für 'heat flux' in LEOs Englisch ⇔ Deutsch Wörterbuch. Mit Flexionstabellen der verschiedenen Fälle und Zeiten ✓ Aussprache und.
heat flux Übersetzung im Glosbe-Wörterbuch Englisch-Deutsch, Online-Wörterbuch, kostenlos. Millionen Wörter und Sätze in allen Sprachen. Übersetzung im Kontext von „, heat flux“ in Englisch-Deutsch von Reverso Context: heat flux. Lernen Sie die Übersetzung für 'heat flux' in LEOs Englisch ⇔ Deutsch Wörterbuch. Mit Flexionstabellen der verschiedenen Fälle und Zeiten ✓ Aussprache und.
Heat Flux Deutsch VideoIt usually consists of a sensor surrounded by a learn more here material, as in this HFP01 heat flux plate. Change the option to calculate stressesrotationsor heat flux. Device to reduce local heat flux through a heat exchanger tube. Read more kann ich Übersetzungen in den Vokabeltrainer übernehmen? Klicke auf einen Zeitpunkt, um diese Version zu laden.
Another problem is that test persons might be moving. The contact between the test person and the sensor can be lost.
For this reason, whenever a high level of quality assurance of the measurement is required, it can be recommended to use a self-calibrating sensor.
Heat flux sensors are also used in industrial environments, where temperature and heat flux may be much higher.
Examples of these environments are aluminium smelting , solar concentrators , coal fired boilers , blast furnaces , flare systems , fluidized beds , cokers , A heat flux sensor should measure the local heat flux density in one direction.
The result is expressed in watts per square meter. The calculation is done according to:. As shown before in the figure to the left, heat flux sensors generally have the shape of a flat plate and a sensitivity in the direction perpendicular to the sensor surface.
Usually a number of thermocouples connected in series called thermopiles are used. General advantages of thermopiles are their stability, low ohmic value which implies little pickup of electromagnetic disturbances , good signal-noise ratio and the fact that zero input gives zero output.
Disadvantageous is the low sensitivity. Usually, the thermal resistance and the thermal capacity of the entire heat flux sensor are equal to those of the filling material.
Stretching the analogy with the electric circuit further, one arrives at the following expression for the response time:.
From this formula one can conclude that material properties of the filling material and dimensions are determining the response time.
As a rule of thumb, the response time is proportional to the thickness to the power of two. Other parameters that are determining sensor properties are the electrical characteristics of the thermocouple.
The temperature dependence of the thermocouple causes the temperature dependence and the non-linearity of the heat flux sensor.
The non linearity at a certain temperature is in fact the derivative of the temperature dependence at that temperature.
However, a well designed sensor may have a lower temperature dependence and better linearity than expected. There are two ways of achieving this:.
Another factor that determines heat flux sensor behavior, is the construction of the sensor. In particular some designs have a strongly nonuniform sensitivity.
Others even exhibit a sensitivity to lateral fluxes. The sensor schematically given in the above figure would for example also be sensitive to heat flows from left to right.
This type of behavior will not cause problems as long as fluxes are uniform and in one direction only.
To promote uniformity of sensitivity, a so-called sandwich construction as shown in the figure to the left can be used.
The purpose of the plates, which have a high conductivity, is to promote the transport of heat across the whole sensitive surface.
It is difficult to quantify non-uniformity and sensitivity to lateral fluxes. Some sensors are equipped with an extra electrical lead, splitting the sensor into two parts.
If during application, there is non-uniform behavior of the sensor or the flux, this will result in different outputs of the two parts. Summarizing: The intrinsic specifications that can be attributed to heat flux sensors are thermal conductivity, total thermal resistance, heat capacity, response time, non linearity, stability, temperature dependence of sensitivity, uniformity of sensitivity and sensitivity to lateral fluxes.
For the latter two specifications, a good method for quantification is not known. This constant is also called sensitivity.
The sensitivity is primarily determined by the sensor construction and operation temperatures, but also by the geometry and material properties of the object that is measured.
Therefore the sensor should be calibrated under conditions that are close to the conditions of the intended application.
The calibration set-up should also be properly shielded to limit external influences. One should avoid air gaps between layers in the test stack.
These can be filled with filling materials, like toothpaste, caulk or putty. If need be, thermally conductive gel can be used to improve contact between layers.
The calibration is done by applying a controlled heat flux through the sensor. By varying the hot and cold sides of the stack, and measuring the voltages of the heat flux sensor and temperature sensor, the correct sensitivity can be determined with:.
If the sensor is mounted onto a surface and is exposed to convection and radiation during the expected applications, the same conditions should be taken into account during calibration.
Doing measurements at different temperatures allows for determining sensitivity as a function of the temperature. While heat flux sensors are typically supplied with a sensitivity by the manufacturer, there are times and situations that call for a re-calibration of the sensor.
Especially in building walls or envelopes the heat flux sensors can not be removed after the initial installation or may be very difficult to reach.
In order to calibrate the sensor, some come with an integrated heater with specified characteristics.
By applying a known voltage on and current through the heater, a controlled heat flux is provided which can be used to calculate the new sensitivity.
The interpretation of measurement results of heat flux sensors is often done assuming that the phenomenon that is studied, is quasi-static and taking place in a direction transversal to the sensor surface.
Dynamic effects and lateral fluxes are possible error sources. The assumption that conditions are quasi-static should be related to the response time of the detector.
The case that the heat flux sensor is used as a radiation detector see figure to the left will serve to illustrate the effect of changing fluxes.
This is the reason why one prefers to work with values that are integrated over a long period; during this period the sensor signal will go up and down.
The assumption is that errors due to long response times will cancel. The upgoing signal will give an error, the downgoing signal will produce an equally large error with a different sign.
This will be valid only if periods with stable heat flow prevail. In the case of simultaneous heat and mass transfer the effective heat flux may substantially, by several orders of magnitude, exceed the value due to heat conduction only.
The radiative heat flux is a flux of electromagnetic radiation and, in contrast to convection and heat conduction, may occur without any intervening medium, i.
For an idealized black body the radiation heat flux is described by Planck's law. The actual radiation flux values can be only lower than this idealized value.
Library Subscription: Guest. DOI:For pressurized water reactors and also for boiling water reactorsthere see more thermal-hydraulic phenomena, which cause a sudden decrease in the efficiency of heat transfer more precisely in the heat transfer coefficient. In read more case of simultaneous heat and mass transfer the effective heat flux may substantially, by several orders of magnitude, exceed the value due to heat conduction. As a rule of thumb, the response time is proportional to the thickness to the power of two. Heat flux or thermal flux is the rate of heat energy transfer through a given surface. This web page is Heat Transfer - Definition. Many sensors are equipped with alarms that inform the click here when the environment becomes unsafe, or even if improvements are needed to make the area safer and to deter a potential fire. An unexpected result shows when the temperature of the sensor changes.