91 results about "Thermal conductivity measurement" patented technology

The invention discloses a quasi-stable state method thermal conductivity measurement apparatus, which includes a direct-current power supply, a data acquisition processing system, two heating plates respectively connected to the direct-current power supply, four thermo-electric couples connected to the data acquisition processing system, four identical samples, seven soaking metal sheets and a measurement container stuffed with thermal insulation material. The thermal conductivity measurement apparatus is characterized in that the upper end of the measurement container is provided with a cover, screw threads are machined in the center of the cover and mounted with a bolt, the bolt presses a compressing metal plate above the heat preserving cover, to decrease the inside contact resistance. Two thin film heating plates with staggered structure are adopted, thereby heating on the samples are uniform. The soaking metal plate is provided with grooves, and the corresponding thermo-electric couples are fixed in the grooves by heat conducting glue, the soaking metal plate further uniforms the heat produced by the heating plate, and grooving on the sample is not needed during test, thereby the experimental investigation to different solid thermal conductivities can be conveniently executed.

An apparatus for thermal conductance measurement includes a first heater assembly having a beam, a platen disposed at an end of the beam, and a heating element and a Resistance Temperature Device (RDT) disposed on the platen. The embodiment further includes a second heater assembly having a second beam, a second platen disposed at an end of the second beam, and a second heating element and a second Resistance Temperature Device (RDT) disposed on the platen. A test rig is also included, and the first heater and second heater assembly are mated to the test rig and separated by a gap length.

The invention discloses thermal conductivity measuring device and method. The heat conductivity measuring device comprises a thermal probe, a thermoelectric couple, a collector and a data processor, wherein the thermal probe is inserted into a sample to be measured for thermal conductivity measurement; the thermoelectric couple is used for measuring the wall surface temperature of the thermal probe; the collector is used for collecting the wall surface temperature measured by the thermoelectric couple and corresponding measuring time; and the data processor is used for combining a thermal conduction differential equation expressing wall surface temperature increase with the thermal conductivity of the sample to be measured, which is obtained by inversely processing the wall surface temperature and the corresponding measuring time. The invention sufficiently considers the thermal probe capacity, the thermal contact resistance between the thermal probe and the sample to be measured, and the like, thereby greatly enhancing the measurement accuracy of parameters, i.e. thermal conductivity and the like.

A heat radiation coefficient C [=Ph / (Th−To)] from a microheater is calculated in accordance with a power Ph applied to the microheater which is supported in air and provided in an ambient gas, a heater temperature Th, and an ambient temperature To at this moment. Further, a thermal conductivity λ(T) of the ambient gas is obtained from the calculated heat radiation coefficient C based on a proportional relation [C=K·λ(T)] between a thermal conductivity λ(T) of the ambient gas and the heat radiation coefficient C at a measurement temperature T [=(Th−To) / 2].

In a local softening point measuring apparatus and thermal conductivity measuring apparatus using a probe microscope as a base, environment of the prob˜ and a sample surface is set to 1 / 100 atmospheric pressure (103 Pa) or lower. Otherwise, a side surface of the probe is coated with a thermal insulation material having a thickness that enables thermal dissipation to be reduced to 1 / 100 or lower, to thereby reduce the thermal dissipation from the side surface of the probe, and exchange heat substantially only at the contacting portion between the probe and the sample surface.

The invention discloses a method for measuring anisotropic material heat conductivity based on a small-plane heat source. The method comprises the following steps: building a three-dimensional heat transfer model of a measured sample in a right-angle coordinate system in a special form under the action of thermal interference; obtaining an analytical solution of temperature change in anisotropic material in a time domain by adopting Laplace transformation, variables separation, transcendental equation solving and inverse Laplace transformation methods; through sensitivity calculation, analyzing linear correlation of sensitivity coefficients of normal heat conductivity and tangential heat conductivity and the effects of parameters on temperature change; building an experiment measurement system, and collecting transient response data of the temperature; and simultaneously determining the normal heat conductivity and the tangential heat conductivity of the measured anisotropic material by an improved Gauss Newton parameter estimation method. The method has the advantages that the transient measurement method which is convenient to implement, fast in measurement and wide in application range and adopts simple steps is provided, and the normal heat conductivity and the tangential heat conductivity of the rectangular anisotropic material can be obtained by once measurement.

Apparatus and a method are described for prospecting for water ice on heavenly bodies with the apparatus consisting of site preparation tools and a water ice detector unit. The apparatus is attached at the end of any robotic arm equipped lander or rover spacecraft; for instance, lander designs such as Mars Phoenix or rover designs such as Mars Spirit and Opportunity. Supported on an internal, moveable carriage, the apparatus is also incorporated into smaller, dedicated water ice detection rover spacecraft. The water ice detection unit inserts electrodes into or against a potential water ice deposit and confirms the presence of water ice by making combination impedance and thermal conductivity measurements.

The invention belongs to the technical field of microelectronics, and in particular discloses a 3 omega thermal conductivity measurement method suitable for a metal film material. In the method, a group of frequency-related heat flow ratios is obtained through an experimental fitting means by utilizing a 3 omega test structure and frequency-related thermal response characteristic based on an improved analytical model. The thermal resistance of an experimental material is deduced from the ratios, and a thermal conductivity value of a tested sample is finally obtained. The thermal conductivity measurement method of the invention can provide rapid and accurate thermal conductivity information of a metal film, so that the application range of 3 omega electrical measurement technology is greatly extended. The 3 omega thermal conductivity measurement method is suitable for measuring nanoscale films, has a simple sample structure, and avoids a complex process structure in the conventional electrical measurement method; therefore, the 3 omega thermal conductivity measurement method can be taken as a rapid characterization means for a thermal parameter of the metal film material, and has application prospect in the microelectronic industrial field.

A thermal conductivity measurement apparatus for measuring a thermal conductivity of a one-dimensional material includes a substrate, a vacuum chamber receiving the substrate and four spaced electrodes. The one-dimensional material spans across the four spaced electrodes. A middle part of the one-dimensional material, located between the second and third electrodes, is suspended. The present disclosure further provides a method for measuring the thermal conductivity of the one-dimensional material.

A method for the determination of gas concentrations xi in a gas mixture using a thermal conductivity detector with a Wheatstone bridge. It comprises the following method steps: measuring the bridge voltage Xa; correcting the measured values for the bridge voltage Xa, in particular with respect to drift; determination of the thermal conductivity of the gas mixture; and determination of at least one gas concentration xi. Preferably, an automatic zero-point correction and an automatic measuring range end value correction occur within the framework of the correction.

The invention belongs to the technical field of material synthesis and provides a filling formula of a modified polytetrafluoroethylene high-thermal-conductivity composite material and an obtaining method of the filling formula. The filling formula comprises 18+ / -0.5 volume percent of graphite and 10 volume percent of carbon fiber. The thermal conductivity of the graphite and carbon fiber double-phase filled modified polytetrafluoroethylene high-thermal-conductivity composite material is researched by a thermal-conductivity measuring device, the mechanical property of the graphite-filled modified polytetrafluoroethylene high-thermal-conductivity composite material is subjected by simulation research by finite element value, the mechanical property of the carbon fiber-filled modified polytetrafluoroethylene high-thermal-conductivity composite material is obtained through theoretical derivation, and the mechanical property of the modified polytetrafluoroethylene high-thermal-conductivity composite material is researched according to an empirical formula, so that the purposes of optimizing and seeking the optimal proportion of the graphite to the carbon fiber systematically is fulfilled, the modified polytetrafluoroethylene high-thermal-conductivity composite material has the optimal thermal conductivity on the premise of meeting the requirement of structural strength, and the corrosion resistance and the heat exchange efficiency of a corrosion-resistant heat exchanger are effectively improved.

The invention relates to a device for measuring the multi-passage heat conductivity, comprising two paths of independent power modules, an upper computer, a main control module, a photon coupled isolation module, a heat pulse control and excitation module, a multi-passage control module and a temperature collection module. The upper computer is respectively connected with a singlechip of the main control module and a multimeter in the temperature collection module through a USB; each I / O in the singlechip is respectively connected with the heat pulse control and excitation module, the multi-passage control module and the temperature collection module after being subjected to photo coupled isolation; the device is provided with two constant-current source circuits and adopts closed loop feedback to realize power constant value output; the multi-passage control module comprises a heating module and a measuring module which both have eight paths of passages; and the main control module selects any passage for collecting, preserving and calculating data in real time. The device has the advantages of convenient measurement, little error, high efficiency, and the like, meets the requirement of high-precision heat conductivity test, and can be further used for testing and researching the heat conductivity of solid body, powder, biological tissue, and the like.

A carbon dioxide gas measurement and control system and method which comprises a thermal conductivity absolute humidity sensor which measures carbon dioxide during dynamic temperature and humidity changes by isolating the particular sensor response for absolute humidity and temperature, i.e., Vm(D,T) in order to track carbon dioxide concentration.

The invention provides a measuring method for thermal conductivity of metal at high temperature. The measuring method comprises the following steps: acquiring thermal diffusion coefficients of a metal sample at different temperatures, wherein the temperatures refer to temperatures except the oxidizing temperature of the metal sample; acquiring thermal conductivity at a corresponding temperature according to the thermal diffusion coefficients and the density and specific heat capacity of the metal sample; acquiring a plurality of groups of initialization fitting regression equation of the temperatures and thermal conductivity according to each group of temperature and thermal conductivity data; subjecting each group of initialization fitting regression equation to test of goodness of fit according to the temperatures and thermal conductivity and establishing a fitting regression model of the temperatures and thermal conductivity; and determining thermal conductivity at different high temperatures according to the fitting regression model. With the method provided by the invention, thermal conductivity of metal at high temperature can be obtained, and accuracy of the obtained thermal conductivity is high.

The invention relates to a porous medium equivalent thermal conductivity measurement method, and belongs to the field of porous medium heat transfer. According to the present invention, based on the APDL program in ANSYS software, the heat transfer process of a model is calculated by using a finite element numerical simulation method, the pore structure of a porous material is randomly distributed according to the volume pore, the relationship between the porous material model equivalent thermal conductivity and the porosity is analyzed, the true density of the porous medium is measured by using a true density meter, the thermal conductivity of the porous medium under a certain porosity is measured by using a laser flashing method, the finite element simulation result is combined, and the porous medium equivalent thermal conductivities at different temperatures are calculated.

The invention discloses an equivalent thermal conductivity measurement method for a wall material. The method comprises the following steps: placing a filling body in a sealed environment which provides a thermal environment for one side of the filling body and a cold environment for the other side of the filling body, and measuring the heat flux QT passing through the filling body after the temperature in the sealed environment is balanced; embedding a test piece to be measured into the filling body in a sealed manner, re-placing the filling body in which the test piece is embedded in the sealed environment in the step 1, measuring the heat flux QS passing through the filling body in which the test piece is embedded after the temperature in the sealed environment is balanced; acquiring the heat flux Q of a heater according to the heat fluxes QT and QS; calculating to obtain the equivalent thermal conductivity lambda e according to the heat flux Q of the heater. The equivalent thermal conductivity measurement method solves the problems that a conventional equivalent heat conductivity measurement method is long in detection period, is greatly influenced by human and environmental factors and cannot truly and effectively reflect the energy-saving effect of a sample. The invention also discloses equivalent heat conductivity measurement equipment which is simple in structure and convenient to use.

The invention discloses a technical scheme and a high-precision measuring method of a measuring device for measuring low-heat-conduction thermal insulation materials, provides a device and a method for measuring the heat conductivity of an active heat-protection type calorimeter by virtue of a quasi-steady-state method as well as a calorimeter correction method and technical scheme based on ASTME2584. Aiming at the shapes and types of different testing materials, an active heat-protection type structural design of a measuring device including a single panel sample, a dual-panel sample and a cylindrical sample is provided. According to the technical scheme, the lateral heat loss can be effectively eliminated, one-dimensional heat flow can be effectively guaranteed, the low heat conductivity measurement and the ultralow heat conductivity measurement on the thermal insulation materials can be realized under high-temperature and ultrahigh-temperature conditions, the continuous dynamic measurement on the heat conductivity in the whole temperature range can be realized, and meanwhile, the measurement accuracy is relatively high.

The invention relates to a measuring instrument and a measuring method for heat conductivity, in particular to a measuring instrument and a measuring method for the heat conductivity of a bulk material. The measuring instrument comprises a heat source, a plurality of temperature sensors, a temperature controller (12) and a signal processor (11); the temperature controller (12) is connected with a heating rod (1) of the heat source; the signal processor (11) is connected with the plurality of temperature sensors, and is also connected with the heating rod (1) of the heat source. The measuring method comprises the following steps: measuring instrument arrangement, reading configuration, parameter setting, data acquisition and heat conductivity calculation. According to the measuring instrument and the measuring method for the heat conductivity, disclosed by the invention, the heat conductivity of a measured medium can be directly measured on site, therefore various influences brought to a testing process by human disturbances are reduced, the negative influence brought to a measuring result due to the fact that the environment is changed by sampling is avoided, and the measurement accuracy of the heat conductivity of the measured medium is greatly improved.

A pressure sensor has a baseplate and a support plate with a membrane. Layers on the membrane and the support plate are connected to a circuit for capacitively measuring pressure to generate a first pressure signal. A thermal conductivity measuring element that generates a second pressure signal has a heating element connected to the baseplate adjacent the support plate at a location opposite from the membrane for protecting the membrane from thermal effects. The method uses the sensor apparatus to generate an output signal representing a measured result when the measured result is above a transition value, on the basis of the first pressure signal and, when the pressure falls below a threshold value, any offset of the first pressure signal is compensated in such a way that determination of the output signal on the basis of the first pressure signal leads to the same result as determination of the output signal on the basis of the second pressure signal.

The invention relates to an electrical impedance tomography-based gel conductivity measurement method, which comprises the following steps of (1) placing gel into an impedance experiment tank filled with conducting solution; (2) performing current excitation and voltage acquisition by an electrical impedance tomography data acquisition system, and reestablishing a conductivity image utilizing the sensitivity algorithm; (3) according to an obtained imaging result, judging whether the conductivity of the gel is equal to that of the solution, is not, performing the step (4), and otherwise, measuring the conductivity of the solution by a liquid conductivity meter to obtain the conductivity of the gel; (4) adjusting the conductivity of the solution, and returning to the step (3). Compared with the prior art, the electrical impedance tomography-based gel conductivity measurement method has the advantage that the conductivity value of the gel of any shape under the excitation of a current of a certain frequency can be measured conveniently as long as the conductivity is uniformly distributed and measuring electrodes are not in contact with the gel.

The invention relates to an anisotropic material heat conductivity measurement method based on a hotwire method. The anisotropic material heat conductivity measurement method comprises the following steps: S1, acquiring a rectangular anisotropic material test sample; S2, building an xyz coordinate system with a length, a width and a height of a cuboid, testing nominal heat conductivity kN1, kN2 and kN3 of three planes N1, N2 and N3 by utilizing a hotwire method, wherein the three planes N1, N2 and N3 are respectively perpendicular to an axis x, an axis y and an axis z; and S3, calculating real heat conductivity kx, ky and kz on the axis x, axis y and axis z according to the following formula: (the formula is shown in the description). Compared with the prior art, the anisotropic material heat conductivity measurement method and apparatus have the advantages that the instruments and devices of the hotwire method are simple and portable, and can simplify the measurement and shorten the test period.

In a method for determining the gas volume flow in gas recirculation at a filling station, by means of a thermal throughflow sensor which is installed in the gas recirculation system of a petrol pump, measurement values are detected, which represent the mass flow of the gas recirculated during refuelling operations from the respective tank of the motor vehicle to be refuelled into a storage tank of the filling station. Furthermore, information on the composition of the recirculated gas is detected, for example by means of a vapour-pressure curve or a thermal-conductivity measurement cell. The mass flow is determined from the measurement values obtained by the thermal throughflow sensor and the information on the composition of the recirculated gas, calibration data being used. This mass flow is converted into a gas volume flow characteristic of the region of the petrol pump valves of the petrol pump. The method is suitable for monitoring the gas recirculation system of the petrol pump with high accuracy.

A porous sample is alternately saturated with at least two saturating fluids with known different thermal conductivities. As at least one saturating fluid a mixture of at least two fluids is used with known and different thermal conductivities. After each saturation thermal conductivity of the saturated sample is measured, and pore space characteristics and matrix thermal conductivity are determined based on the results of thermal conductivity measurements.

The invention discloses an intelligent deposited ash sampling device and method for the online measurement of effective heat conductivity of deposited ash, and belongs to the technical field of deposited ash collection and heat conductivity measurement of a power plant boiler tail flue. The device comprises a supporting body outer sleeve, a sampling probe connected with one end of the supporting body outer sleeve, a temperature measuring unit and an intelligent accumulated ash purging unit; the thickness of an ash deposition layer on the surface of the probe can be monitored on line in real time through an ultrasonic thickness gauge; the temperatures of the outer wall and the inner wall of the sampling probe can be measured in real time through a first thermocouple and a second thermocouple, and the real-time temperature of the ash deposition layer on the surface of the probe can be iteratively solved through an iterative method, so that the effective thermal conductivity of the ash deposition layer on the surface of the probe can be accurately measured on line in real time. By the adoption of the technical scheme, the real-time online monitoring can be conducted on the effective heat conductivity of the ash deposition layer while sampling is conducted, so that intelligent sweeping control over the ash deposition layer is facilitated, and the meaningful reference and guidance are brought to the ash removal of an actual boiler.

The invention discloses hot wire (hot wire source) fixing structures for a thermal conductivity measurement device by a transient hot wire method and an application example for the measurement device, which are characterized in that: the reliable and stable hot wire fixing structures are realized, and the thermal conductivity measurement of fluid at different temperatures and under different pressures can be realized by combining the exampled application example. Experiments prove that the hot wire fixing structures are very firm and the measurement accuracy is high.

The invention discloses a pyroelectric detector-based thin sample heat conductivity measurement device and a method thereof, and belongs to the technical field of thin sample heat conductivity measurement devices and methods thereof, aiming at solving the problems that the heat conductivity of a thin sample cannot be accurately measured because of complicated operation, low measurement speed and requirement for half-temperature rise time. The device comprises a signal generator, an infrared pulse laser, a semi-reflecting and semi-transmitting beam splitter, a testing film sample, a testing pyroelectric detector, a reference pyroelectric detector and an oscilloscope, wherein the infrared pulse laser is controlled by the signal generated by the signal generator to output a required waveform; the wave is split into two light beams by the semi-reflecting and semi-transporting light splitter and is irradiated to the testing pyroelectric detector carrying the to-be-detected material and the reference pyroelectric detector to obtain a voltage response signal; two paths of voltage signals have different responses due to different heat conductivities, and the heat conductivity can be obtained through responding full temperature rise difference. The device can be used for measuring the heat conductivity of a film sample.

The present invention discloses an integrated online measurement system for thermophysical property parameters of nanofluid cutting fluid, consisting of a gas path system, a fluid path system, a nanofluid thermal conductivity measurement device, a measurement device for a convective heat transfer coefficient and a nanofluid / workpiece heat partition ratio of the nanofluid cutting fluid, and a grinding force and grinding temperature measurement device or a milling force and milling temperature measurement device; the nanofluid thermal conductivity measurement device is located in the fluid path system; the gas path system provides pressure for the nanofluid in the fluid path system, two nozzles lead out from the fluid path system, and the nanofluid gas spray ejected by the nozzle I is sprayed onto the surface of a workpiece I to form the measurement device for the nanofluid convective heat transfer coefficient and the nanofluid / workpiece heat partition ratio; and the nanofluid gas spray ejected by the nozzle II is sprayed onto the surface of a workpiece II to form the grinding force and grinding temperature measurement device.

The invention discloses a thermal conductivity test method aiming at lithium batteries and other irregular samples. According to the irregular sample thermal conductivity test method, a sample to be tested is placed in three states, that is, a constant temperature T0 state, a constant temperature T1 state with strong convection heat-changing coefficient on the surface and a surface adiabatic state, and an unsteady heat transfer process between the inner part of the sample to be tested and environments when heat is changed is constructed; stored energy of the sample to be tested is taken as a heat source or heat sink, internal and external heat transfer tests are achieved without damaging the sample, the thermal shielding effect caused by good thermal conductivity materials on the surface of uneven samples can be avoided, and the heating problem caused by an irregular shape of the sample can be solved. The thermal conductivity test method can be used in nondestructive tests of equivalent thermal conductivity coefficient of square lithium batteries with metal shells, and can further be used in nondestructive tests of thermal conductivity of an irregularly shaped sample difficult to be detected by other conventional methods.

The invention discloses a method for predicting material thermal conductivity on the basis of finite difference method of three-dimensional image, and belongs to the method for predicting the material thermal conductivity on the basis of finite difference method. The method has the basic principle: 1) an image analysis method is used for distinguishing different phases or components in the image; 2) a computer language program is used for reading the position and color information of all pixels into a computer memory; 3) each pixel is constructed into a cell element, and the cell element is endowed with the thermal conductivity according to the component to which the cell element belongs; 4) a stable thermal conductivity equation is dispersed, calculating a heat transfer coefficient matrix is calculated, and a calculation equation set is constructed; 5) a temperature field is obtained by the calculation equation set; and 6) the material equivalent thermal conductivity is calculated. The three-dimensional model is adopted to accurately obtain a thermal conductivity result, and the finite difference method is adopted to shorten calculation time and save memory consumption. The whole process is automatically finished, and the method is very practical for the model with a huge node amount.