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396 results about "Thermal diffusivity" patented technology
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In heat transfer analysis, thermal diffusivity is the thermal conductivity divided by density and specific heat capacity at constant pressure. It measures the rate of transfer of heat of a material from the hot end to the cold end. It has the SI derived unit of m²/s. Thermal diffusivity is usually denoted α but a,h,κ, K, and D are also used. The formula is: α=k/ρcₚ where k is thermal conductivity (W/(m·K)) cₚ is specific heat capacity (J/(kg·K)) ρ is density (kg/m³) Together, ρcₚ can be considered the volumetric heat capacity (J/(m³·K)).
Surgical sealing surfaces and methods of use
ActiveUS7220951B2Fast transferHighly stable current-limitingDielectric heatingSurgical instruments for heatingOmni directionalSwitching time
Various embodiments provide compositions that exhibit positive temperature coefficient of resistance (PTCR) properties for use in thermal interactions with tissue—including thermal sensing and I2R current-limiting interactions. Embodiments also provide tissue-engaging surfaces having PTCR materials that provide very fast switching times between low resistance and high, current-limiting resistance. One embodiment provides a matrix for an electrosurgical energy delivery surface comprising a PTCR material and a heat exchange material disposed within an interior of the matrix. The PTCR material has a substantially conductive state and a substantially non-conductive state. The heat exchange material has a structure configured to have an omni-directional thermal diffusivity for exchanging heat with the PTCR material to cause rapid switching of the PTCR material between the conductive state and non-conductive state. Preferably, the structure comprises a graphite foam having an open cell configuration. The matrix can be carried by tissue contacting surfaces of various electrosurgical devices.
Owner:ETHICON ENDO SURGERY INC
Electrosurgical cutting instrument
InactiveUS20050283149A1Easy to transportSurgical needlesSurgical instruments for heatingThermal diffusivityEngineering
An electrosurgical instrument is provided. The electrosurgical instrument includes an active electrode in close proximity to a return electrode. The active electrode has a first thermal diffusivity. The second electrode has a second thermal diffusivity greater than the first thermal diffusivity. The volume, shape, and thermal diffusivity of the second electrode facilitate the transport of heat.
Owner:STRYKER CORP +1
Surgical sealing surfaces and methods of use
ActiveUS20070146113A1Fast transferHighly stable current-limitingCurrent responsive resistorsHeating element shapesOmni directionalPositive temperature
Various embodiments provide compositions that exhibit positive temperature coefficient of resistance (PTCR) properties for use in thermal interactions with tissue—including thermal sensing and I2R current-limiting interactions. Embodiments also provide tissue-engaging surfaces having PTCR materials that provide very fast switching times between low resistance and high, current-limiting resistance. One embodiment provides a matrix for an electrosurgical energy delivery surface comprising a PTCR material and a heat exchange material disposed within an interior of the matrix. The PTCR material has a substantially conductive state and a substantially non-conductive state. The heat exchange material has a structure configured to have an omni-directional thermal diffusivity for exchanging heat with the PTCR material to cause rapid switching of the PTCR material between the conductive state and non-conductive state. Preferably, the structure comprises a graphite foam having an open cell configuration. The matrix can be carried by tissue contacting surfaces of various electrosurgical devices.
Owner:ETHICON ENDO SURGERY INC
Radiant heater for heating the building material in a laser sintering device
InactiveUS8073315B2Reduce the temperatureThermal inertiaDomestic stoves or rangesDrying solid materials with heatRadiant heaterMetallurgy
A radiant heating for heating the building material in a laser sintering device and a laser sintering device having such a radiant heating are described. The radiant heating has a sheet-like heat radiating element (113, 213, 313), which is characterized in that it is made of a material, that has a low thermal inertia with a thermal diffusivity of preferably more than 1.5·10−4 m2 / s and preferably has a thickness of 2 mm or less.
Owner:EOS ELECTRO OPTICAL SYST
Apparatus and method for measuring thermal conductivity
InactiveUS20060222043A1Increase heightLow thermal conductivityThermometer detailsMaterial thermal conductivityFemtosecond pulsed laserPump probe
An apparatus and method for measuring and mapping thermal conductivity and thermal diffusivity at micrometer scale resolution. The apparatus and method utilize a mode-locked femtosecond pulsed laser in a pump-probe configuration to analyze time-domain thermoreflectance of a specimen to evaluate its thermal conductivity in micro-scale, so that, if desired, an image of thermal conductivity distribution of micro-scale regions may be obtained therefrom. A multi-layer, complete three-dimensional model that takes into account the entire three-dimensional heat flow in cylindrical coordinates enables micro-scale measurements to be made at an accuracy of about 90% of well-accepted values.
Owner:CAHILL DAVID GERARD
Method and apparatus for measuring thermophysical properties
InactiveUS20060039443A1Obtain dataRadiation pyrometryMaterial thermal conductivityElectrical resistance and conductanceThermal diffusivity
The present invention provides a method for measuring thermophysical properties that includes: rapid resistive self-heating of a specimen by using a heating current; emitting a light to the specimen heated by the rapid resistive self-heating of the specimen; measuring a temperature change of the specimen induced by emitting the light to the specimen; and deriving a thermal diffusivity of the specimen from the temperature change induced by emitting the light to the specimen.
Owner:NAT INST OF ADVANCED IND SCI & TECH
Device for measuring thermal diffusivity
InactiveCN101929968AMonitor strength in real timeCorrect response timeMaterial thermal conductivityMaterial heat developmentSample MeasureMeasurement device
The invention provides a device for measuring a thermal diffusivity. The device comprises an excitation light source, an optical control device, a vacuum heating furnace, a temperature controlling device, a temperature measuring device and a data acquiring and processing device, wherein the excitation light source generates excitation light beams; the optical control device is provided with an optical component group, a light beam mass spectrometer and an energy meter and regulates the energy of the excitation light beams through a replaceable optical element in the optical component group; a heating element for heating a sample is arranged in the vacuum heating furnace; the temperature controlling device is used for controlling the heating temperature of the vacuum heating furnace; the temperature measuring device amplifies a temperature rise signal of the sample measured by a detector through a pre-amplifier and transmits the amplified signal to the data acquiring and processing device; the data acquiring and processing device comprises a data acquiring system and a data processing system; the data acquiring system transmits all acquired data signals to the data processing system; and the data processing system analyzes and repeatedly and theoretically corrects the data signals. The device for measuring the thermal diffusivity designed by the invention has the advantages of reducing the measuring repeatability of the thermal diffusivity of a material to be less than 1 percent, lowering uncertainty of measurement, improving the level of thermal diffusivity measurement and laying foundations for the establishment of a standard thermal diffusivity device in China, the preparation of a standard thermal diffusivity substance and the establishment of a standard thermal diffusivity database.
Owner:NAT INST OF METROLOGY CHINA +1
Folding preventing less-layer graphene powder, components of composite material thereof, and application
ActiveCN103030138AReduce surface tensionEasy to peelGrapheneElectrically-conductive paintsConductive coatingSupercapacitor
The invention discloses folding preventing less-layer graphene powder, components of composite material thereof and application, and belongs to the technical field of graphene preparation. The folding preventing less-layer graphene powder can be applied to conductive plastics, conductive coating paint and printing ink, and can also be applied to mechanical enhancement of conductive adhesive and various and various resins. In addition, the graphene powder can also be applied to the preparation of electrodes of lithium batteries and supercapacitors, composite material requiring high thermal diffusivity, and any other material requiring good electric conductivity, thermal conductivity and mechanical enhancement. The graphene powder has the characteristics that special dispersant is utilized to prepare graphene solution, and secondary folding of graphene piece layers is effectively prevented during the drying process, so that thinner less-layer graphene powder is obtained, and excellent electric conductivity, mechanical property and thermal conductivity can be obtained in polymer or other base material through lower additive amount.
Owner:SUPERCDONGGUAN TECH
Halogen-free high heat-resistant and heat-conducting resin film and manufacturing method thereof
ActiveCN102660210ASolve the brittleness problemImprove cooling effectNon-macromolecular adhesive additivesFilm/foil adhesivesEpoxyHeat conducting
The invention discloses a halogen-free high heat-resistant and heat-conducting resin film and a manufacturing method thereof. The halogen-free high heat-resistant and heat-conducting resin film is prepared by semi-curing of a heat-conducting resin liquid, wherein the heat-conducting resin liquid is prepared from 70 to 100 parts of a halogen-free epoxy resin, 0 to 30 parts of one or more flexibilizers, 80 to 120 parts of one or more solvents, 1 to 20 parts of one or more curing agents, 0.01 to 1 part of one or more promoters, 0.5 to 5.0 parts of a coupling agent and 80 to 600 parts of one or more high heat-conducting filling materials. The halogen-free high heat-resistant and heat-conducting resin film has a thermal conductivity great than or equal to 2.5W / m.K and heat resistance (at a temperature of 300 DEG C) great than or equal to 300s. The halogen-free high heat-resistant and heat-conducting resin film has flexibility so that the problem of brittleness of the traditional heat-conducting materials is solved. An aluminum substrate prepared from the halogen-free high heat-resistant and heat-conducting resin film is suitable for electronic products such as LED, vehicle systems and variable-frequency power sources needing good heat conductivity, can greatly improve the thermal diffusivity of the electronic products, and has high reliability and energy-saving and environmental-protection effects.
Owner:ZHEJIANG WAZAM NEW MATERIAL CO LTD
Graphite Film and Graphite Composite Film
ActiveUS20100196716A1Improve flex resistanceExcellent thermal diffusivityGraphiteSemiconductor/solid-state device detailsFolding enduranceElectronic instrument
An object of the present invention is to provide a graphite film, and a graphite composite film both having an excellent thermal diffusivity which can sufficiently manage heat dissipation of electronic instruments, precision instruments and the like, along with an excellent flex resistance which can withstand application to bent portions.Means for Resolution of the present invention is a graphite film exhibiting the number of reciprocal foldings being 10,000 times or more as measured using a rectangular strip test piece having a width of 15 mm until the test piece breaks in a MIT folding endurance test under conditions of: a curvature radius R of the bending clamp being 2 mm; a left-and-right bending angle being 135°; a bending rate being 90 times / min; and a load being 0.98 N.
Owner:KANEKA CORP
Electrosurgical tool with moveable electrode that can be operated in a cutting mode or a coagulation mode
InactiveUS20090138013A1Easy to transportSurgical needlesSurgical instruments for heatingElectricityThermal diffusivity
An electrosurgical instrument is provided. The electrosurgical instrument includes an active electrode in close proximity to a return electrode. The active electrode has a first thermal diffusivity. The second electrode has a second thermal diffusivity greater than the first thermal diffusivity. The volume, shape, and thermal diffusivity of the second electrode facilitate the transport of heat.
Owner:THORNE JONATHAN O +1
On-line testing and analyzing device and method for microelectromechanical system component material parameter
Wherein, using electric excitation and electric parameter measurement to analyze material parameters and extract on-line; applying dc, ac and transient voltage or current to the MEMS device to force target generating opposite action and changing electric parameters (I, R, U and C); measuring parameters, and obtaining the required parameters (R, E, F, etc) according to software.
Owner:SOUTHEAST UNIV
Highly thermally conductive resin molded article
ActiveUS20110027565A1Efficiently and easily disperseImprove thermal conductivitySemiconductor/solid-state device detailsSynthetic resin layered productsDiffusion AnisotropyHexagonal boron nitride
An object of the present invention is to industrially easily mold a molded article which is excellent in thermal conductivity, electric insulation property, low density, and an injection moldability and has a thermal conduction anisotropy. The present invention relates to a highly thermally conductive resin molded article having a thermal diffusion anisotropy, the highly thermally conductive resin molded article comprising a resin composition, the resin composition containing at least resin (A) and plate-like hexagonal boron nitride powder (B) in a (A) / (B) volume ratio falling within a range of 90 / 10 to 30 / 70, the resin (A) including a thermoplastic polyester resin and / or a thermoplastic polyamide resin, the highly thermally conductive resin molded article having a thickness of not more than 1.3 mm in a part of or all over a three-dimensional shape of the highly thermally conductive resin molded article, a thermal diffusivity measured in a plane direction of the highly thermally conductive resin molded article, being (i) two or more times higher than a thermal diffusivity measured in a thickness direction of the highly thermally conductive resin molded article and (ii) not less than 0.5 mm2 / sec.
Owner:KANEKA CORP
Method and apparatus for localized infrared spectrocopy and micro-tomography using a combination of thermal expansion and temperature change measurements
A method and a system for generating a high spatial resolution multi-dimensional image representing the chemical composition of a sample. Highly localized IR light is used to cause the heating and thermal expansion of the sample. Modulating this IR light will cause this effect to take place at various depths of the material. The method and system of the present invention are used to generate a chemical profile of the sample using a combination of: (i) measurements of the thermal expansion and temperature change caused by absorbing IR radiation together; and (ii) measurements of the thermal expansion properties and thermal properties (such as thermal diffusivity and conductivity) of sites on the surface of the sample and the material surrounding it.
Owner:ANASYS INSTR
Continuous, lawinar flow water-based particle condensation device and method
InactiveUS20040020362A1Improve performanceLarge temperature differenceCombination devicesSolidificationWater basedThermal diffusion coefficient
An apparatus and method for producing a diffusive, continuous laminar flow for particle growth via condensation of vapors with a mass diffusivity near or higher than the thermal diffusivity of the surrounding gas. In an exemplary embodiment, the method uses the condensation of water vapor onto particles suspended in air.
Owner:AEROSOL DYNAMICS INC
LED module road lamp cap with adjustable irradiation angle and high radiation capability.
InactiveCN101482241AHigh light efficiencyLow costPlanar light sourcesMechanical apparatusModular compositionIlluminance
A lamp cap of an LED module street lamp with high thermal diffusivity and adjustable lighting angle belongs to the technical field of semi-conductor illumination. The lamp cap comprises a lamp cap upper cover, a lamp cap lower cover, a supporting framework, a lamp cap trim cover, a junction box, a plurality of LED light source drive, a power supply and at least one LED light source module; the LED light source module is connected and fixed with the supporting framework by an end cover, the lamp cap trim cover is fixed at the head of the supporting framework, and the upper cover and the lower cover of the lamp cap are appositioned face to face and are fixedly connected at the tail of the supporting framework. By adopting LED light source and scientific and reasonable design, the invention has the advantages of high light efficiency, stability, energy saving, and environmental protection, etc. By making use of the design of modularization combination, the LED light source module can satisfy the requirements of diverse heights and lighting angles by adding or reducing LED light source modules according to application condition, thus one lamp has various usages. The invention has wide application range, low cost and convenient assembly. The lighting angle of the LED light source module can be adjusted to realize optimal light distribution requirements of different roads.
Owner:史杰
Thermal imaging measurement of lateral diffusivity and non-invasive material defect detection
InactiveUS20020126730A1Accurate methodRadiation pyrometryMaterial heat developmentMaterial defectOrthogonal coordinates
A system and method for determining lateral thermal diffusivity of a material sample using a heat pulse; a sample oriented within an orthogonal coordinate system; an infrared camera; and a computer that has a digital frame grabber, and data acquisition and processing software. The mathematical model used within the data processing software is capable of determining the lateral thermal diffusivity of a sample of finite boundaries. The system and method may also be used as a nondestructive method for detecting and locating cracks within the material sample.
Owner:THE UNITED STATES AS REPRESENTED BY THE DEPARTMENT OF ENERGY
Graphene enhanced aluminium-based silicon carbide composite, preparation method and application thereof
ActiveCN106591666AImprove reliabilityImprove thermal conductivitySemiconductor/solid-state device detailsSolid-state devicesThermal diffusivityElectronic packaging
The invention relates to a graphene enhanced aluminium-based silicon carbide composite and a preparation method thereof. The composite comprises the following substances by volume percent: 40% to 70% of silicon carbide and 0.5% to 5% of graphene, and the balance being aluminium alloy. The composite is prepared through the powder metallurgy method and is obtained through the steps of blending, powder mixing, bagging, vacuum degassing and hot iso-hydrostatic forming treatment. The composite has the advantages of high thermal conductivity, high strength, high plasticity, light weight, good thermal diffusivity, isotropy, and the like, and becomes a second-generation electronic packaging material with wide application.
Owner:BEIJING BAOHANG ADVANCED MATERIALS CO LTD
Graphite film and method for producing graphite film
ActiveUS20120121880A1Good lookingReduce spacingGraphiteSynthetic resin layered productsThermal diffusivityGraphite
Provided is a long and large-area graphite film having improved thermal diffusivity and flex resistance, and accompanied by ameliorated ruffling. According to a method for producing a graphite film, in which graphitization of a heat-treated film consisting of a carbonized polymer film is carried out in a state being wrapped around an internal core, the method being characterized in that a heat treatment is executed by controlling distance(s) between the internal core and the film, and / or between the layers of the film, a graphite film accompanied by significantly ameliorated ruffling can be obtained.
Owner:KANEKA CORP
Method and device for testing thermal physical property of solid material with independent probe by using harmonic method
ActiveCN101782541AGuaranteed NDTReal-time display of torque valueMaterial thermal conductivityMaterial heat developmentElectricityThermal diffusivity
The invention relates to a method and a device for testing the thermal physical property of a solid material with an independent probe by using a harmonic method. The device comprises the independent probe, a pressure adjusting part, a torque measuring part and a harmonic measuring unit, wherein the independent probe is positioned between two identical samples to be tested to form a sandwich structure and is arranged parallel to a sample fixing table; the pressure adjusting part is positioned and pressed on the upper end face of the first sample to be tested; the sandwich structure is arranged on the sample fixing table; the torque measuring part is sleeved on one end of the pressure adjusting part; the harmonic measuring unit is electrically connected with the independent probe; and a torsion value and contact thermal resistance between the independent probe and the two samples to be tested are fitted and calculated according to a harmonic measurement principle. In the test, the sandwich structure is arranged on a lug boss of the sample fixing table, the pressure adjusting part is adjusted until the torsion value is displayed to be the optimal torsion value, and then the thermal conductivity coefficient and the thermal diffusivity of the sample to be tested are tested by the harmonic method. Differences among thermal conductivity values of the samples to be tested under the condition of a plurality of torsion values smaller than the optimal torsion value are measured and calculated for obtaining the contact thermal resistances between the samples to be tested and the independent probe under the condition of the plurality of torsion values.
Owner:INST OF ENGINEERING THERMOPHYSICS - CHINESE ACAD OF SCI
Spark ignition type internal combustion engine
InactiveUS20130255651A1Reduce thicknessIncrease volumeInternal combustion piston enginesCylinder headsCombustion chamberThermal insulation
In a spark ignition engine, a thermal insulation thin layer is formed over a wall surface, facing an inside of a combustion chamber, of a base material forming the combustion chamber, and for a thermal conductivity λ [W / (m·K)], a thermal diffusivity κ [mm2 / s], and a thickness L [μm] of the thermal insulation thin layer, L≧16.7×λ and L≦207.4×(κ)0.5 are satisfied. With such a configuration, a heat loss Q_total escaping from gas in a cylinder to the wall of the combustion chamber over all strokes can be reduced, and the thermal efficiency can be improved without inducing degradation of knocking due to an increase in an amount of heating Q_intake of the gas in the cylinder during an intake stroke.
Owner:TOYOTA CENT RES & DEV LAB INC
Bubbler tube with integral inlet pipe and bimetal core for injection molding tools and method of making the bubbler tube
InactiveUS6425752B1Excellent thermal diffusivityHigh strengthFoundry mouldsFood shapingThermal diffusivityHigh intensity
A mold assembly including moveable mold parts, one of which includes a plurality of hollow cavities. Each hollow cavity forms an outer wall of an elongated, generally annular portion of a molded part and the other mold part includes a corresponding plurality of core elements, which form an inner wall of the same portion of the molded part. Each core is disposed within a corresponding cavity to define a generally annular mold chamber portion for receiving molten material to be molded to form the shape of the portion of the molded part. Each core element includes a cooling apparatus and each cavity includes an outside cavity-cooling device. Each core element includes a first portion made of high strength material and a tip portion made of material having a greater heat diffusivity and heat transfer coefficient than said first portion.
Owner:CHECK JOHN M
Method and device for determination of thermal properties of solid bodies
InactiveUS20110106485A1High measurement accuracyImprove accuracyTesting/calibration apparatusMaterial thermal conductivityTime rangeThermal diffusivity
The invention relates to the area of thermophysical studies of media and is intended for the determination of thermal properties of solid media by placing a measuring device on the surface of the medium. A heater, which is made in the form of a flexible membrane capable of taking the shape of the solid body surface under the action of the hold-down pressure and which additionally serves as a temperature sensor, is pressed to the solid body surface by using a hold-down element in such a way as to ensure that the heater shape fits the shape and irregularities of the solid body surface. The heater temperature is registered throughout the heater surface during and after the heating. The thermal conductivity and thermal diffusivity of the solid body are determined by processing the heater temperature measurement data both in the time range from the start of the solid body heating to the start of the thermal convention of the ambient medium and after the termination of the solid body heating process.
Owner:SCHLUMBERGER TECH CORP
Ultrahigh heat-conduction diamond/aluminum composite material and preparation method of ultrahigh heat-conduction diamond/aluminum composite material
ActiveCN104313385ASolve the strength problemSolve the problem of forming special-shaped componentsMaterials preparationThermal diffusivity
Owner:HARBIN INST OF TECH
Thermal Transport Characteristics of Human Skin Measured In Vivo Using Thermal Elements
InactiveUS20170347891A1Minimize impactReduce measurement errorDiagnostic recording/measuringSensorsHuman skinMedicine
Devices and methods useful for sensing epidermal tissue are disclosed. Thermal data from the devices allows for determination of thermal transport properties, such as thermal conductivity, thermal diffusivity and heat capacity per unit volume. From these data, tissue parameters, such as hydration state, stratum corneum thickness, epidermis thickness and vasculature structure may be determined. These parameters may be used, for example, to evaluate the efficacy of dermatological compounds.
Owner:THE BOARD OF TRUSTEES OF THE UNIV OF ILLINOIS
Thermal detection and imaging of electromagnetic radiation
InactiveUS20110204231A1High sensitivityImprove performanceMaterial analysis by optical meansPhotovoltaicsEnergy absorptionParticle physics
The current invention provides a method for improving the sensitivity of bolometric detection by providing improved electromagnetic power / energy absorption. In addition to its role in significantly improving the performance of conventional conducting-film bolometric detection elements, the method suggests application of plasmon resonance absorption for efficient thermal detection and imaging of far-field radiation using the Surface Plasmon Resonance (SPR) and the herein introduced Cavity Plasmone Resonance (CPR) phenomena. The latter offers detection characteristics, including good frequency sensitivity, intrinsic spatial (angular) selectivity without focusing lenses, wide tunability over both infrared and visible light domains, high responsivity and miniaturization capabilities. As compared to SPR, the CPR-type devices offer an increased flexibility over wide ranges of wavelengths, bandwidths, and device dimensions. Both CPR and SPR occur in metallic films, which are characterized by high thermal diffusivity essential for fast bolometric response.
Owner:TECHNION RES & DEV FOUND LTD
Photoelectronic device and image sensor
ActiveUS20140239278A1Improve photoelectric conversion efficiencyReduce leakage currentFinal product manufactureSolid-state devicesImage sensorThermal diffusivity
Disclosed are a photoelectronic device including a first electrode including a first metal; an active layer disposed between the first electrode and a second electrode; and a diffusion barrier layer disposed between the first electrode and the active layer; the diffusion barrier layer including a second metal, wherein the second metal has a thermal diffusivity that is lower than a thermal diffusivity of the first metal, and wherein the first electrode and the diffusion barrier layer are configured to transmit light, and an image sensor including the photoelectronic device.
Owner:SAMSUNG ELECTRONICS CO LTD
Method for measuring thermal diffusivity and interface thermal resistance
InactiveUS20020080850A1Material thermal conductivityMaterial heat developmentThermal forceThermal diffusivity
An object of the invention is to make it possible to correctly and easily measure a thermal diffusivity within a three-layer substance containing an non-metal substance. A non-metal film 1 whose thermophsical properties are unknown is disposed between a first metal film 2 and a second metal film 3, thereby forming a sample having a three-layer structure. The metal films 2 and 3 have predetermined known thermophsical properties, belong to the same sort of substance and have the same thickness. The three-layer substance is disposed on a transparent substrate 4 and is heated from below the second metal film 3, using a picosecond light pulse coming from below and passing through the transparent substrate 4. The light pulse used in the irradiation is converted into a heat in the second metal film 3 during only one picosecond, with such heat diffusing through interface / non-metal film layer / interface and thus arriving at the first metal film 2. By measuring a temperature change on the surface of the first metal film 2, it is possible to perform correct measurement by using the thermoreflectance method formerly suggested in a patent application by the inventors of the present invention.
Owner:NAT INST OF ADVANCED IND SCI & TECH
Method and apparatus for measuring thermal diffusivity of materials through transient fluorescence
ActiveCN106596626ALow requirements for shape and appearanceCause damageMaterial heat developmentObservational errorMeasurement device
The invention provides a method and an apparatus for measuring thermal diffusivity of materials through transient fluorescence. The method includes the steps of: (1) irradiating the surface of a sample by means of modulating pulse laser as a heating light source for the sample and an excitation light source for a fluorescence signal; (2) collecting the fed-back fluorescence signal when the sample is excited, and comparing the signal intensity with a fluorescence intensity-temperature curve of the sample, thus obtaining temperature information of the sample; (3) changing the pulse width of the pulse laser for several times to obtain transient temperature increase of the sample in different transient heating periods; and (4) according to an analytic solution expression of temperature field of a heat conduction model of the to-be-tested sample, substituting several groups of test data and performing fitting to obtain the thermal diffusivity of the material. On the basis of the method, a measurement apparatus platform is correspondingly designed. The method is not liable to cause sample damage, has low measurement error and is high in efficiency during the measurement of the thermal diffusivity of materials.
Owner:WUHAN UNIV
Experimental device for testing heat conductivity coefficient of building material based on quasi steady state and unsteady state methods
The invention provides an experimental device for testing a heat conductivity coefficient of a building material based on quasi steady state and unsteady state methods, relates to the field of a testing technology of thermophysical parameters of a building material, and solves the problems that an existing thermophysical parameter experimental device can not simultaneously load the measurement processes by using three methods including a quasi steady state method, a normal power method and a heat pulse method, and one-time testing time is long and a measurement maximum relative error is large. An anode and a cathode of a low-potential potentiometer are correspondingly connected with a switch control interface of an oil immersed key conversion switch; thermoelectromotive force signals output by thermocouples are respectively connected into a thermoelectromotive force signal output end of the oil immersed key conversion switch; cold ends of the thermocouples are respectively inserted into an ice bottle containing an ice-water mixture; measuring ends of the thermocouples are respectively contacted with a testing piece to be tested; a heating resistor is used for heating the testing piece to be tested. The theoretical error analysis and the actual measurement prove that the measurement maximum relative errors are as follows: the heat conductivity coefficient is less than or equal to 5.1%, the thermal diffusivity is less than or equal to 9.2% and the specific heat value is less than or equal to 7.7%; the requirement on precision by engineering is met.
Owner:HARBIN INST OF TECH
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