Gradient Heatmetry in a Burners Adjustment Bobylev, Pavel G.; Pavlov, Andrey V.; Proskurin, Vyacheslav M. ...
Inventions,
12/2022, Letnik:
7, Številka:
4
Journal Article
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Measuring the heat flux in the furnace of industrial boilers is an urgent task in the power industry. Installing the measuring instruments directly into the furnace is a laborious and complex ...process. It requires a complete shutdown of the boiler, which incurs economic costs. It is most efficient to use portable probes with measuring insert. The created cooled probe with a heterogeneous gradient heat flux sensor is a unique and versatile tool that allows for the configuration and control of the operation of power boilers. This article compares experimental values with calculation methods. The obtained heat flux per unit area is in good agreement with the theoretical concepts when the values are averaged. The technique used in this paper makese it possible to determine the maximum heat-stressed zones and areas with stable or unstable combustion. The main combustion zones that are typical for the flaring of any fuel are identified. This approach allows us to consider various approaches to heat transfer enhancement during the combustion of both liquid and gaseous fuels. Comparison of experimental results with the data of other authors is not quite exact due to the complexity of the experiment. The study of burners in this configuration has not previously been considered in the literature.
► Anisotropic heat flux sensors made from single crystal of bismuth and from artificial anisotropic materials is presented. ► The calibration of both types shows the dependence of the output voltage ...from heat flux with error 0.64% and 6.8% respectively. ► The response time found from direct experiment is about 10ns. ► New sensors can be used with environmental temperature 1300K.
The paper studies gradient heat flux sensors (GHFS) based on artificial anisotropic thermoelements. Fundamentals, manufacturing technique and examples of applications in thermal measurement experiments are presented. Comparison of different types of sensors is provided.
The paper describes a unique method of heat flux measurement, i.e., gradient heatmetry. Gradient heatmetry is performed using gradient heat flux sensors (GHFS) developed on the anisotropic ...thermoelements basis. The principle of GHFS’ operation leads to the fact that their response time is about 10 ns, and the volt-watt sensitivity does not depend on the thickness. GHFS are compared with other types heat flux sensors, with the GHFS features depending on the materials being described. The theory and examples of gradient heatmetry applications in thermophysical experiment are provided.
All heat transfer processes from a solid body to a gas or a liquid are connected with flow characteristics in the vicinity of the streamlined body surface. As far as plenty of flow properties are ...changing rapidly, it is important to know both heat transfer and flow properties in a certain location and at a certain time. We present a new method of the simultaneous velocity field measurement and heatmetry. By "heatmetry" we mean science and practice of the heat flux measurement (by analogy with the thermometry). The velocity field was obtained by the particle image velocimetry and the local heat flux - by the gradient heat flux sensor. The advantage of the method was exemplified on the heat transfer from a circular cylinder in cross flow.
Heat transfer is a limiting factor in the performance of electrical machines. Measuring the heat flux in an electrical machine is traditionally carried out indirectly with temperature measurements as ...there are only a few sensors for heat flux measurements. This paper describes a new experimental method to measure the local heat flux inside an electrical machine. The measurement was proven successful in the air gap of the permanent magnet machine, 37 kW 2400 min -1 , under an influence of the air gap magnetic flux. The heat flux was measured by using sensors based on the transverse Seebeck effect. The test machine was an axial flux permanent magnet machine with two stator stacks and one internal, ironless rotor disc. A gradient heat flux sensor was installed in the air gap on the stator side. Local Nusselt and Reynolds numbers were calculated according to the measured heat flux results and compared with the results given by traditional methods to verify the new measurement method.
A series of 23 novel bis-phosphonium salts based on pyridoxine were synthesized and their antibacterial activities were evaluated in vitro. All compounds were inactive against gram-negative bacteria ...and exhibited the structure-dependent activity against gram-positive bacteria. The antibacterial activity enhanced with the increase in chain length at acetal carbon atom in the order n-Pr>Et>Me. Further increasing of length and branching of alkyl chain leads to the reduction of antibacterial activity. Replacement of the phenyl substituents at the phosphorus atoms in 5,6-bis(triphenylphosphonio(methyl))-2,2,8-trimethyl-4H-1,3-dioxino4,5-cpyridine dichloride (compound 1) with n-butyl, m-tolyl or p-tolyl as well as chloride anions in the compound 1 with bromides (compound 14a) increased the activity against Staphylococcus aureus and Staphylococcus epidermidis up to 5times (MICs=1–1.25μg/ml). But in practically all cases chemical modifications of compound 1 led to the increase of its toxicity for HEK-293 cells. The only exception is compound 5,6-bistributylphosphonio(methyl)-2,2,8-trimethyl-4H-1,3dioxino4,5-cpyridine dichloride (10a) which demonstrated lower MIC values against S. aureus and S. epidermidis (1μg/ml) and lower cytotoxicity on HEK-293 cells (CC50=200μg/ml). Compound 10a had no significant mutagenic and genotoxic effects and was selected for further evaluation. It should be noted that all bis-phosphonium salt based on pyridoxine were much more toxic than vancomycin.
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