Summary of the invention
The technical matters that the present invention will solve provides a kind of instrument and method of protective heat plate method heat conducting coefficient measuring, can use the high-precision mensuration coefficient of heat conductivity of simple structure and method.
For solving the problems of the technologies described above, the critical piece of protective heat plate method thermal conductivity measuring apparatus of the present invention is: main part, low-temperature receiver TT&C system, thermal source TT&C system, intelligent measuring apparatus, computing machine transmission, semiconductor refrigerating power supply and stabilized voltage supply.Main part is made up of hot plate, cold drawing, test specimen pressing system; Hot plate by the back of the body guarded hot plate, main heating plate, protect heating plate and form; Main hot plate is made up of primary heater and metal soaking plate; Protect heating plate by protecting well heater and the metal soaking plate is formed, cold drawing is made up of aluminium sheet, semiconductor cooler, cooling water system; The thermal source of back of the body guarded hot plate and the low-temperature receiver of cold drawing are provided, are made up of the exact constant temperature tank that two nested structures are identical, Water Tank with Temp.-controlled is made up of refrigerating circuit, tank, water pump, stirring system, heating temperature-controlling system, water temperature display etc.; The semiconductor refrigerating power supply is independent of outside main part, low-temperature receiver TT&C system and the thermal source TT&C system.
A kind of preferred as above-mentioned protective heat plate method thermal conductivity measuring apparatus; Said cooling water system has comprised a cover Water Tank with Temp.-controlled; By Water Tank with Temp.-controlled stable cooling water flow is provided; When test needed the cold drawing temperature to be set in more than 5 ℃, directly the adjusting through the Water Tank with Temp.-controlled temperature realized the temperature control to cold drawing; When test needs the cold drawing temperature to be set in below 5 ℃, control the cold drawing temperature with semiconductor cooler, this moment, Water Tank with Temp.-controlled played the semiconductor cooler cooling effect.
The thermal conductivity detector as other preferred embodiments, the test sample made into a 300mm × 300mm, thickness greater than 15mm, less than 50mm, the sample resistance ≥ 0.1m
2 · k / w; hot plate, cold plate size of 300mm × 300mm; dorsal guarded hot plate with 40mm thick aluminum processed into the back guarded hot plate heated by a precision heat sink to provide a stable, temperature stability better than ± 0.005 ℃, temperature water out of the use of the reverse flow of liquid spiral groove boards; metal hot plate used for blackened brass produced and processed, the radiation rate of greater than 0.8; Lord, retaining the hot plate flatness of 0.04mm, not less than flatness 0.025%; primary, retaining heater with 0.1mm thick constantan foil from corrosion, the use of semi-cured insulation board; cold plate surface oxidation treatment, the plate surface flatness was 0.04mm, flatness is not less than 0.025%; cold, hot plate temperature measured by eight P
t 1000 platinum resistance sensor, hot plate 6, cold plate 2, in addition to select high-end P
t 1000 platinum resistance sensors, also alternative P
t 1000 with a high-precision platinum resistance temperature tank rigorous screening, including sump temperature resolution 0.0001 degrees.
Coefficient of heat conductivity assay method of the present invention may further comprise the steps:
Measure sample thickness, after the completion sample is installed, at first; Open alternating current steady voltage plug,, must wait the output gauge outfit of voltage stabilizer to point to 220V because the output of alternating current steady voltage plug has time delay; Could open the total power switch on main frame right side, at this moment the gauge outfit energising work of cold and heat source TT&C system.Their temperature displayed are respectively the water temperature in two tanks, then open the power supply of intelligent measuring apparatus and two water pumps.Look the height of the design temperature of hot and cold plate, determine the unlatching of two tunnel refrigerating circuit power supplys, be higher than environment temperature more than 5 ℃, need not open like set point temperatures; Otherwise then open; Then the thickness d of sample is imported intelligent measuring apparatus.Instrument gets into the measurement state automatically, automatic heating-cooling process, and temperature automatically controlled, follow the tracks of temperature control.After observing back of the body guarded hot plate and reaching temperature controlling point, under the situation of not having refrigeration, the temperature control degree of stability should be superior to ± 0.002 ℃ in; Having under the situation of refrigeration, degree of stability should be superior to ± 0.005 ℃ in.When cold, back of the body guarded hot plate temperature tend towards stability, observe main heating plate and guarded hot plate temperature and the tracking situation of carrying on the back the guarded hot plate temperature again.Less than ± 0.002 ℃, upper and lower fluctuation is less than ± 1% in the coefficient of heat conductivity one hour like the temperature difference of three plates, and experiment can finish, and prints experimental result.
Under the not high condition of testing element precision level; Circuital current (comprising control circuit) is very little to the overall accuracy influence of instrument; But in the process that improves the instrument temperature test, the high more circuital current of the precision of temperature and power test is big more to the overall precision influence of conductometer.Particularly in whole thermal conductivity measuring apparatus, refrigeration unit power is maximum, and its operation has fatal influence to the precision of instrument.Therefore in order to reduce the influence of refrigeration unit circuit to the test components and parts, the present invention independently divides refrigeration unit out, for the precision that improves thermal conductivity measuring apparatus provides a good solution.
With said thermal conductivity measuring apparatus the insulation material of several unlike materials has been carried out actual measurement work; The experimental data repeatability that obtains is relatively good; Experimental result has reached index that national standard proposed and measurement range; The manufacture level that instrument is described can reach requirement of actual application, and the flow process of detection also is rational.Experimental result shows that this thermal conductivity measuring apparatus has the value of applying.
Embodiment
As shown in Figure 1, thermal conductivity measuring apparatus is mainly by parts such as main part, low-temperature receiver TT&C system 1, thermal source TT&C system 2, intelligent measuring apparatus 3, computing machine transmission 4, semiconductor refrigerating power supply 5 and stabilized voltage supplys 6.
(1) main part is made up of hot plate 7, cold drawing 8, test specimen pressing system.Hot plate 7 is hardware core parts of instrument with cold drawing 8, and fundamental purpose is to make to detect time necessary and reach steady state (SS) with the space, and makes hot plate and cold drawing rational in infrastructure, manufacturing process accurate with reliably, this influence to instrument performance is very big.Hot plate, cold drawing are of a size of 300mm * 300mm.
Hot plate 7 by the back of the body guarded hot plate, main heating plate, protect heating plate and form.Back of the body guarded hot plate adopts the thick aluminium sheet of 40mm to be processed into; By the exact constant temperature tank stable heat is provided again; Require temperature stability be superior to ± 0.005 ℃, the liquid frid of spirality reverse flow is adopted in the thermostatted water turnover, this design can make the temperature homogeneity of plate face reach effect preferably.The thermal source of back of the body guarded hot plate and low-temperature receiver are made up of two cover exact constant temperature tanks.
Main hot plate is made up of primary heater and metal soaking plate, protects heating plate by protecting well heater and the metal soaking plate is formed.The size and the test specimen thickness proportion relation of main, guarded hot plate, and with edge thermal loss E
eWith unbalanced error E
gRelevant, therefore, must take all factors into consideration when designing main guarded hot plate, make error E
eWith unbalanced error sum E=E
e+ E
gMinimum.The problem of relevant this respect had been done extensive work both at home and abroad, for this this instrument designs according to the size that GB 10294 recommends.Soaking plate adopts brass sheet to make and carries out the blacking processing, and its radiance is greater than 0.8.Flatness main, that protect soaking plate is 0.04mm, and irregularity degree is less than 0.025%.
Lord, guard heater using 0.1mm thick constantan foil from corrosion, the use of prepreg insulation, this process not only ensures the hot plate and the heater has good electrical insulation between the have good thermal contact.Well heater main, guarded hot plate is controlled by intelligent measuring apparatus, follows the tracks of the temperature of back of the body guarded hot plate, and the temperature of three-lane road is consistent, and temperature gap is controlled in ± 0.001 ℃.
Cold drawing 8 is made up of aluminium sheet, semiconductor cooler, cooling water system.The plate face carries out oxidation processes, and the flatness of plate face is 0.04mm, and irregularity degree is less than 0.025%.Cooling water system mainly comprises another set of Water Tank with Temp.-controlled, by Water Tank with Temp.-controlled stable cooling water flow is provided.When test needed the cold drawing temperature to be set in more than 5 ℃, directly the adjusting through the Water Tank with Temp.-controlled temperature just can realize the temperature control to cold drawing; When test needs the cold drawing temperature to be set in below 5 ℃, control the cold drawing temperature with semiconductor cooler, this moment, tank played the semiconductor cooler cooling effect.
For adapting to the measurement of different-thickness sample, cold drawing is removable on worktable, and cold side is equipped with hold down gag, contacts with the tight of sample to guarantee hot and cold plate.The thickness of sample is answered≤50mm.
Hot and cold plate temperature is measured and is adopted P
t1000 platinum sensors, totally 8.6 of hot plates, 2 of cold drawings are aspect the use of temperature sensor, except selecting high-end P
tOutside 1000 platinum sensors, also alternative P
t1000 RTDs are with the strict screening of high-precision thermostatic oil bath, and wherein the temperature resolution of oil groove reaches 0.0001 degree.
(2) cold and heat source TT&C system
The thermal source of back of the body guarded hot plate and the low-temperature receiver of cold drawing are provided, form by the exact constant temperature tank that two nested structures are identical.The structural representation of one of which cover is as shown in Figure 2:
It is made up of refrigerating circuit, tank 9, water pump 10, stirring system 11, heating temperature-controlling system 12, water temperature display 13 etc.
The setting of temperature and control are all accomplished by temperature-controlling system, open total power switch, and the temperature control instrument of thermal source promptly starts; After instrument is flashed " 888888 " several seconds; The numerical value that occurs is the temperature in the thermal source tank, if do not carry out new setting, and setting that the instrument acquiescence is last and beginning temperature control.
The low-temperature receiver of cold drawing is given by two cover TT&C systems.When the control of cold drawing temperature more than 5 ℃, directly by bosh, a stable low-temperature receiver is provided.Be lower than this temperature, by semiconductor cooler low-temperature receiver be provided, the recirculated water of tank plays the effect of cooling at this moment.Open total power switch, the temperature control instrument of low-temperature receiver promptly starts, and shows the current temperature value and the design temperature of tank in the tank, and what the start back was shown is last design temperature, as changing design temperature, need only by add, the subtrahend key.
(3) intelligent measuring apparatus
Intelligent measuring apparatus adopts microcomputer system, and for the accuracy that guarantees to measure, each electronic component all passes through selected.Instrument has 8 tunnel temperature survey passages, and main heating plate well heater DC voltage, electric current, power measurement are arranged; Two road P.I.D regulating systems are arranged, respectively master, guarded hot plate are carried out temperature control.Power measurement is through realizations such as advanced standard resistance and triode amplifiers.After the tester set cold and hot plate target temperature, instrument got into the measurement state automatically, and the data of each collection are carried out computing; Calculate the medial temperature of leading, protecting, carry on the back hot plate through the backstage, cold drawing medial temperature, heat flow density, test specimen thermal resistance, parameters such as coefficient of heat conductivity.Divide two screens to show by 5 cun color LCD screens.In the measuring process of instrument after start, master, the survey of guarded hot plate, temperature control carry out synchronously.Main guarded hot plate is cheated the temperature of following the tracks of back of the body guarded hot plate eventually according to the P.I.D adjusting parameter of self, realizes full automatic temperature control process.After instrument reaches thermal equilibrium state, the printing test result.
(4) semiconductor refrigerating power supply
When test specimen cold drawing temperature is set in below 5 ℃, need with semiconductor cooler and semiconductor refrigerating power supply.Adopt semiconductor cooler, power supply is relatively independent, adopts independent stabilized voltage supply, and refrigeration work consumption is not less than 1000W.
Semiconductor refrigerating power supply top gauge outfit is an observing and controlling temperature table, and the bottom gauge outfit is a reometer, the unit ampere.In order to prevent when temperature automatically controlled, the semiconductor cooler electric current changes and the interference that brings, adopts manual temperature control, promptly gives a constant refrigeration electric current.As want cooling rate fast, and can strengthen export ratio at any time, reduce export ratio more immediately.In order to prevent, can only use manual setting cold drawing temperature to thermometric interference.
Under the not high condition of testing element precision level; Circuital current (comprising control circuit) is very little to the overall accuracy influence of instrument; But in the process that improves the instrument temperature test, the high more circuital current of the precision of temperature and power test is big more to the overall precision influence of conductometer.Particularly in whole thermal conductivity measuring apparatus, refrigeration unit power is maximum, and its operation has fatal influence to the precision of instrument.Therefore in order to reduce the influence of refrigeration unit circuit to the test components and parts, the present invention independently divides refrigeration unit out, for the precision that improves thermal conductivity measuring apparatus provides a good solution.
(5) notebook computer
Measure situation for clear demonstration, show, and be convenient to the electronics file with the computing machine liquid crystal display.
(6) 220V AC voltage regulator
For guaranteeing the stability of Alternating Current Power Supply, can get rid of the fluctuation interference that some AC network brings.
The instrument important technological parameters:
1. measurement range: sample thermal resistance>=0.1m
2K/w
2. hot plate temperature: 10 ℃~60 ℃
3. cold drawing temperature :-20 ℃~40 ℃
4. specimen size: 300mm * 300mm * (15~50) mm
5. supply voltage: exchange 200V ± 20V; 50HZ
6. environmental baseline: 20 ℃ ± 10 ℃; Relative humidity<80%
7. measuring error: the medial temperature of mensuration is measured thermal property and can be accurate to≤± 2% (temperature difference is between 15 ℃~30 ℃) during near room temperature.In whole measurement ranges of device≤± 5% (the test specimen medial temperature is minimum at-5 ℃; The highest 50 ℃; The temperature difference is between 15 ℃~30 ℃).
This instrument is single test specimen formula protective heat plate device.One side of heating unit is made a constant-heat source with the liquid frid of spirality reverse flow, is controlled to be zero all the time with master, the temperature difference of protecting heating unit surface, makes its no type of thermal communication mistake.So just guaranteed that the center metering units sets up the one dimension hot-fluid; To the accurate measurement of metering units primary heater power and the accurate measurement of hot and cold surface temperature; Input specimen thickness d; Wherein, R represents the test specimen thermal resistance can to record thermal resistance
and the coefficient of heat conductivity
of test specimen; Δ T represents the temperature difference of test specimen cold surface and hot surface; A represents the test specimen useful area; The Q representative is through the power of test specimen useful area; D represents specimen thickness.
Requirement and installation to sample:
1. make one of 300mm * 300mm sample, thickness is greater than 15mm, less than 50mm.For hard material, the specimen surface irregularity degree, should less than thickness ± 2%.
2. when measuring compressible sample, be encased inside the pillar (as making) of four small bore low thermal conductivities at the periphery of sample, with the compression of restriction sample with bamboo chopsticks.
3. use vernier caliper, measure the thickness of sample, at least one point of every limit, four limits have been surveyed and have been averaged, as the thickness d of sample.
4. sample is installed: open the muff on the main frame, move cold drawing, put into sample, sample near hot plate, is moved cold drawing, sample is contacted with hot and cold plate, tighten leading screw one circle this moment again, and sample and hot and cold plate are combined closely.The stay-warm case that closes, sample installs.
Measure sample thickness, after the completion sample is installed, at first; Open alternating current steady voltage plug,, must wait the output gauge outfit of voltage stabilizer to point to 220V because the output of alternating current steady voltage plug has time delay; Could open the total power switch on main frame right side, at this moment the gauge outfit energising work of cold and heat source TT&C system.Their temperature displayed are respectively the water temperature in two tanks, then open the power supply of intelligent measuring apparatus and two water pumps.Look the height of the design temperature of hot and cold plate, determine the unlatching of two tunnel refrigerating circuit power supplys, be higher than environment temperature more than 5 ℃, need not open like set point temperatures; Otherwise then open; Then the thickness d of sample is imported intelligent measuring apparatus.Instrument gets into the measurement state automatically, automatic heating-cooling process, and temperature automatically controlled, follow the tracks of temperature control.After observing back of the body guarded hot plate and reaching temperature controlling point, under the situation of not having refrigeration, the temperature control degree of stability should be superior to ± 0.002 ℃ in; Having under the situation of refrigeration, degree of stability should be superior to ± 0.005 ℃ in.When cold, back of the body guarded hot plate temperature tend towards stability, observe main heating plate and guarded hot plate temperature and the tracking situation of carrying on the back the guarded hot plate temperature again.Like the temperature difference of three plates less than ± 0.002 ℃, and upper and lower fluctuation.Upper and lower fluctuation is less than ± 1% in the coefficient of heat conductivity one hour, and experiment can finish, and prints experimental result.
Be appreciated that under the prerequisite that does not deviate from inner characteristic of the present invention, the present invention also can have various deformation, be not limited in the concrete structure of above-mentioned embodiment, and should in scope thereof, do the understanding of broad sense.In a word, the present invention should comprise those conspicuous to those skilled in the art conversion or substitute.