JPH06242034A - Measuring method of thermal conductivity - Google Patents
Measuring method of thermal conductivityInfo
- Publication number
- JPH06242034A JPH06242034A JP5028094A JP2809493A JPH06242034A JP H06242034 A JPH06242034 A JP H06242034A JP 5028094 A JP5028094 A JP 5028094A JP 2809493 A JP2809493 A JP 2809493A JP H06242034 A JPH06242034 A JP H06242034A
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- fluid
- thermal conductivity
- sensor
- time
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 50
- 239000012530 fluid Substances 0.000 claims abstract description 67
- 238000012937 correction Methods 0.000 claims abstract description 30
- 238000010438 heat treatment Methods 0.000 claims abstract description 29
- 230000020169 heat generation Effects 0.000 claims description 56
- 238000005259 measurement Methods 0.000 claims description 55
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 16
- 239000007787 solid Substances 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 238000012545 processing Methods 0.000 claims description 10
- 239000013078 crystal Substances 0.000 claims description 8
- 235000011187 glycerol Nutrition 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 3
- 230000002123 temporal effect Effects 0.000 abstract 3
- 238000002474 experimental method Methods 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 239000002002 slurry Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 206010037660 Pyrexia Diseases 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 230000036962 time dependent Effects 0.000 description 2
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Landscapes
- Measuring Temperature Or Quantity Of Heat (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、流体や固体と熱的に接
触する発熱センサーを発熱させ、該発熱センサー温度の
非定常変化と流体や固体の温度から流体や固体の熱伝導
率を計測する方法に関するものである。例えば、各種被
加工流体の熱伝導率は該流体の温度や組成により変化
し、かつこの変化により加熱や冷却の制御条件に変動を
来すことから加工工程における重要な管理項目となる。
また固体の熱伝導率は各種設備や構造物の伝熱特性を設
計・管理・制御する上で重要な物性値である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention heats a heat generating sensor that is in thermal contact with a fluid or solid, and measures the thermal conductivity of the fluid or solid from the unsteady change in temperature of the heat generating sensor and the temperature of the fluid or solid. It is about how to do it. For example, the thermal conductivity of various fluids to be processed changes depending on the temperature and composition of the fluid, and this change causes a change in heating and cooling control conditions, which is an important control item in the processing process.
The thermal conductivity of solids is an important physical property value in designing, managing and controlling the heat transfer characteristics of various equipment and structures.
【０００２】[0002]
【従来の技術】従来、非定常細線法により液体の熱伝導
率を計測する例として、以下のものがあげられている。 １．「液体の熱伝導率の高精度測定に関する研究」 長坂雄次、長島昭 日本機械学論文集４７巻４１７号
（昭５６−５）８２１−８２９頁 ２．「液体の熱伝導率の高精度測定に関する研究」 長坂雄次、長島昭 日本機械学論文集４７巻４１９号
（昭５６−７）１３２３−１３３１頁 ３．「熱物性ハンドブック」 日本熱物性学会編 １９９０．５．３０ 養賢堂発行５
６８−５７３頁 液体の熱伝導率の測定は非定常法と定常法に分類され
る。発熱体として金属細線等を利用する非定常細線加熱
法とは、発熱開始直後における発熱体温度の経時的な上
昇変化を利用する方法であり、定常法とは非定常状態を
経過して経時的に該温度が一定に安定し続ける状態にお
ける発熱体周囲の時間に依存しない温度分布を利用する
方法である。流体の熱伝導率測定に際して一般に定常法
は測定に伴う被測定流体の温度上昇による対流伝熱の影
響を受けやすく、高精度測定には適さないのに対し、非
定常法は測定時間が短く、かつ、対流発生を直接検出
し、対流発生以前のデータだけを利用して熱伝導率の正
確な計測が確実に実施できるため液体の熱伝導率の測定
は通常、非定常法で行われている。文献１、２はその代
表事例であって、試料中に鉛直に配置した金属細線を通
電加熱し、この時の加熱細線自体の経時的温度変化と発
熱量から熱伝導率を算出する方法を利用しており、詳細
に報告されている。文献３は定常法、非定常法ともに既
知の例をあげて説明されている。その他の従来技術とし
ては、特開平１−１８０４４４号、特開平３−１７５４
２号、特開平３−１７５４３号があげられる。特開平１
−１８０４４４号は非定常細線加熱法を用いた測定方法
において、センサーからの信号を読み取るブリッジ回路
での電気抵抗を要因とする測定誤差について検討された
ものである。特開平３−１７５４２号は非定常細線加熱
法を用いて測定する場合の流体の熱対流を押さえること
によって、温度上昇と電流通電時間の対数との直線関係
を得て熱伝導率を計測する方法である。特開平３−１７
５４３号は非定常細線加熱法を用いて測定する場合の流
体の熱対流を押さえるため、細線を被測定物中で鉛直姿
勢を維持しながら、ともに自由落下させて見掛け上、重
力を０とし、浮力に起因する自然対流の発生を防止した
上で熱伝導率を計測する方法である。これら文献等で基
本的に利用される熱伝導率の算出基礎式は、鉛直線状熱
源の直径ｄ＝０、長さ＝∞（無限大）、媒質の密度ρ及
び比熱Ｃｐが均一かつ一定という仮定のもとにフーリエ
の熱伝導方程式 を境界条件 △θ（ｒ，ｔ） ＝ ０ ｔ≦
０、ｒ＝任意（ｒ＝鉛直方向の距離、ｔ＝時間） のもとで解かれたものであり、近似解析解として （λは熱伝導率、θは温度、ａは温度伝導率、ｄは微分
記号、△θは発熱体と流体の温度差） が得られる。この式は非定常細線加熱法を用いて熱伝導
率を求めるための基礎式として広く利用されている。な
お、該式が線状細線の直径がかぎりなく小さく、細線の
直径による測定誤差が無視できるものであるという前提
に基づいて導かれたものであることに注意を要する。2. Description of the Related Art Conventionally, the following examples have been given as examples of measuring the thermal conductivity of a liquid by the unsteady thin wire method. 1. "Study on high-precision measurement of thermal conductivity of liquids" Yuji Nagasaka, Akira Nagashima Vol. 47, No. 417 (Sho 56-5), 821-829 2. "Study on high-precision measurement of thermal conductivity of liquids" Yuji Nagasaka, Akira Nagashima Vol. 47, No. 419 (Sho 56-7) 1323-1331 3. "Thermophysical property handbook" edited by The Japan Society of Thermophysical Properties 1990.5.30, published by Yokendo 5
Page 68-573 The measurement of the thermal conductivity of liquid is classified into the unsteady method and the steady method. The unsteady thin wire heating method that uses a metal thin wire as a heating element is a method that utilizes the time-dependent increase in the temperature of the heating element immediately after the start of heat generation. In addition, it is a method of utilizing a temperature distribution that does not depend on time around the heating element in a state where the temperature continues to be constant and constant. When measuring the thermal conductivity of a fluid, the steady-state method is generally susceptible to convective heat transfer due to the temperature rise of the fluid to be measured and is not suitable for high-precision measurement, whereas the unsteady-state method requires a short measurement time. Moreover, since the convection generation is directly detected and the accurate measurement of the thermal conductivity can be reliably performed using only the data before the convection generation, the thermal conductivity of the liquid is usually measured by the unsteady method. . References 1 and 2 are typical examples of the method, in which a thin metal wire vertically arranged in a sample is electrically heated, and the thermal conductivity is calculated from the time-dependent temperature change and heat generation amount of the thin heating wire itself. And has been reported in detail. Document 3 is explained using known examples of both stationary and transient methods. Other conventional techniques include Japanese Patent Laid-Open Nos. 1-180444 and 3-1754.
2 and JP-A-3-17543. JP-A-1
No. -180444 is an examination of a measurement error caused by an electric resistance in a bridge circuit for reading a signal from a sensor in a measurement method using the unsteady thin wire heating method. JP-A-3-17542 discloses a method for measuring the thermal conductivity by suppressing the thermal convection of a fluid when using the unsteady thin wire heating method to obtain a linear relationship between the temperature rise and the logarithm of the current conduction time. Is. Japanese Patent Laid-Open No. 3-17
No. 543 suppresses the thermal convection of the fluid when measuring using the unsteady thin wire heating method. Therefore, while maintaining the vertical posture of the thin wire in the object to be measured, the thin wire is made to fall freely and the gravity is set to 0, This method measures the thermal conductivity while preventing the occurrence of natural convection due to buoyancy. The basic formula for calculating the thermal conductivity basically used in these documents is that the diameter d = 0 of the vertical heat source, the length = ∞ (infinity), the density ρ of the medium and the specific heat Cp are uniform and constant. Fourier's heat conduction equation under the assumption Is the boundary condition Δθ (r, t) = 0 t ≦
0, r = arbitrary (r = vertical distance, t = time) As an approximate analytical solution. (Λ is thermal conductivity, θ is temperature, a is temperature conductivity, d is differential symbol, Δθ is temperature difference between heating element and fluid). This equation is widely used as a basic equation for obtaining the thermal conductivity using the unsteady thin wire heating method. It should be noted that the formula is derived based on the premise that the diameter of the linear thin wire is as small as possible and the measurement error due to the diameter of the thin wire is negligible.
【０００３】[0003]
【発明が解決しようとする課題】文献にあげられる熱伝
導率の非定常法による測定方法は、非定常細線加熱法と
いう測定技術を基本として紹介されており、通常、発熱
源となる細線としては直径が数十ミクロン程度以下のも
のを使用していることは従来技術に述べたが、（１）式
によれば該直径の値の大小に関わらず加熱継続時間の長
さの対数値ｌｎｔと加熱細線と被測定流体の温度差Δθ
は直線関係となり、同直線の傾きと発熱量Ｑから熱伝導
率λが算出されるはずである。しかし、実際に測定され
るｌｎｔ ｖｓ Δθの関係は多くの場合曲線となって
観測される。従来、この傾向はよく知られており、文献
では該曲線からその直線部分を見つけだし、同直線の傾
きを得、（１）を用いて算出していた解いていた。しか
し、直径１００μの白金線を発熱源として純水中で計測
すると経験的には発熱開始から２〜４秒の間に対流発生
の現象が見られる。対流が発生すると対流伝熱の影響を
受けて正確な熱伝導率の測定は不可能になり、２〜４秒
以前の本来、直線関係が想定される領域であるにかかわ
らず、直線性を失う事例が観測された。この原因として
は発熱センサー内部の熱伝導に起因する場合と、該測定
値を処理するシステム側に起因するものが考えられる。
特に測定時間としては２秒以内の短時間を要請されるこ
とから測定システム系に起因する応答遅れの存在が無視
できないと言える。以上から、発熱センサーにおいて対
流による対流伝熱の影響を受けないうちに被測定流体の
熱伝導率を計測するには、発熱センサーの構造や測定シ
ステムに起因する、特に計測時間に関する誤差の補正を
して、測定値の該直線性を発現させる必要がある。従来
技術にあげる文献ではこの問題に対する考察がなく、
（１）式が常に成立するという前提にたち、実測結果が
曲線となった場合はこの曲線から直線に近い部分を抜き
出して直線と仮定する方法を採っている。しかし、この
ようなやり方では人為的判断が介在するため熱伝導率測
定値の正確性に欠けた。特開平１−１８０４４４号及び
特開平３−１７５４２号、特開平３−１７５４３はいず
れも非定常法を用いるもので、高精度の熱伝導率測定に
関する出願である。特開平１−１８０４４４号では測定
センサーの電極部やリード線の電気抵抗などに起因する
測定誤差を軽減するものであるが、測定装置の誤差に関
する根本的要因について検討はされていない。特開平３
−１７５４２号は被測定物の対流の影響を小さくするた
め被測定物の下部温度を低温にし重力方向に対して負の
温度勾配をもたせ、測定時の直線関係を長く維持できる
ようにしたもので、負の温度勾配を実現する具体性に欠
けるものであり、かつこの条件を適宜実現することは機
器構成が複雑になるため簡便な方法とは言えない。特開
平３−１７５４３号は対流の抑制を目的として被測定物
と細線を自由落下させる構成であるが、落下に伴うセン
サー自体の破壊等のため反復利用に困難性が伴う。本発
明は以上に鑑み、発熱センサーを利用した非定常細線加
熱法による熱伝導率の測定を実施するにあたり、従来検
討されていなかった測定精度に影響する測定技術に由来
する誤差要因である時間に関して検討したもので、非定
常細線加熱法における発熱センサーの発熱開始時刻の検
討精度を向上するため、発熱センサーの構造に起因する
測定誤差を解消する測定環境を設定し、発熱量、温度差
及び任意基準点からの経過時間の各計測技術に由来する
誤差要因を取り除いた計測を行い、各計測値と基礎式と
の比較によって、任意基準点と発熱開始時点の偏差を時
間の補正項として得ることにより、熱伝導率の測定装置
における測定時間に起因する誤差を補正し、正確な熱伝
導率を測定する方法を提供することを目的とする。The method for measuring the thermal conductivity by the unsteady method, which is mentioned in the literature, is introduced based on the measuring technique called the unsteady thin wire heating method. Although it has been described in the prior art that the diameter is about several tens of microns or less, according to the equation (1), the logarithmic value lnt of the length of the heating duration is obtained regardless of the value of the diameter. Temperature difference between heating wire and fluid to be measured Δθ
Has a linear relationship, and the thermal conductivity λ should be calculated from the slope of the straight line and the calorific value Q. However, the actually measured relationship of lnt vs Δθ is often observed as a curve. Conventionally, this tendency is well known, and in the literature, the straight line portion was found from the curve, the slope of the straight line was obtained, and the calculation was performed using (1). However, when a platinum wire having a diameter of 100 μm is used as a heat source for measurement in pure water, empirically, a phenomenon of convection is observed within 2 to 4 seconds after the start of heat generation. When convection occurs, accurate heat conductivity cannot be measured due to the influence of convective heat transfer, and linearity is lost before 2 to 4 seconds, even though it is an area where a linear relationship is supposed. Cases were observed. It is considered that this is caused by the heat conduction inside the heat generation sensor and that caused by the system side processing the measured values.
In particular, since the measurement time is required to be as short as 2 seconds or less, it can be said that the existence of a response delay due to the measurement system system cannot be ignored. From the above, in order to measure the thermal conductivity of the fluid to be measured before it is affected by convective heat transfer due to convection in the heat generation sensor, it is necessary to correct the errors due to the structure of the heat generation sensor and the measurement system, especially the measurement time. Therefore, it is necessary to develop the linearity of the measured value. There is no consideration for this problem in the literature cited in the prior art,
Based on the premise that the formula (1) is always satisfied, when the actual measurement result is a curve, a method of extracting a portion close to a straight line from this curve and assuming it to be a straight line is adopted. However, in such a method, the accuracy of the measured value of thermal conductivity was lacking due to the intervention of artificial judgment. JP-A-1-180444, JP-A-3-17542, and JP-A-3-17543 all use the non-steady state method, and are applications for highly accurate thermal conductivity measurement. Japanese Unexamined Patent Publication No. 1-180444 reduces the measurement error caused by the electric resistance of the electrode portion of the measurement sensor and the lead wire, but does not consider the fundamental factor relating to the error of the measuring device. JP-A-3
In order to reduce the effect of convection on the object to be measured, No. -17542 has a lower temperature on the object to be measured and has a negative temperature gradient with respect to the direction of gravity so that the linear relationship during measurement can be maintained for a long time. However, it is not concrete to realize a negative temperature gradient, and appropriately realizing this condition is not a simple method because the device configuration becomes complicated. Japanese Unexamined Patent Publication No. 3-17543 has a structure in which an object to be measured and a thin wire are allowed to freely fall for the purpose of suppressing convection, but it is difficult to repeatedly use the sensor because the sensor itself is destroyed due to the fall. In view of the above, the present invention, when performing the measurement of the thermal conductivity by the unsteady thin wire heating method using a heat generation sensor, with respect to the time that is an error factor derived from the measurement technology that affects the measurement accuracy that has not been previously studied In order to improve the accuracy of studying the heat generation start time of the heat generation sensor in the unsteady thin wire heating method, the measurement environment that eliminates the measurement error due to the structure of the heat generation sensor was set, and the heat generation amount, temperature difference, and arbitrary Perform the measurement of the elapsed time from the reference point by removing the error factors derived from each measurement technology, and obtain the deviation between the arbitrary reference point and the heat generation start point as a time correction term by comparing each measured value with the basic formula. Therefore, it is an object of the present invention to provide a method for correcting an error due to a measurement time in a thermal conductivity measuring device and measuring an accurate thermal conductivity.
【０００４】[0004]
【課題を解決するための手段】以上の目的を達成すべ
く、本発明は非定常細線加熱法を利用して流体もしくは
固体の熱伝導率を求めるにあたり、熱伝導率既知の流体
もしくは固体中に流体もしくは固体と熱的に接触し、発
熱作用を有するとともに自らの温度を計測可能な発熱セ
ンサーを配置して該発熱センサーを発熱せしめ、該発熱
センサー自体の温度の非定常変化を経時的に計測し、発
熱開始から計測した同計測時間の対数値と該温度の相関
関係を求め、この関係が理論値と一致する相関を示す測
定装置の測定処理時間に起因する実測時間の補正時間を
数値的手法により求めるようにして流体もしくは固体の
熱伝導率を測定する構成とした。そして、補正時間を求
めるにあたり非定常計測する温度は流体もしくは固体の
温度と発熱センサーの温度の差とし、熱伝導率が既知の
流体として均一温度（０℃）が容易かつ確実に実現でき
る純氷晶と純水の混合物（スラリー）もしくは熱伝導率
の温度依存性が実用上無視できるグリセリンを使用し
た。また、熱伝導率の測定方法を実施するにあたって、
測定装置の測定処理時間に起因する補正値を代入し、以
下の式によって熱伝導率を求める。 （λ＝熱伝導率、ｔ0＝実測時間、ｔ＝補正時間、Ｑ＝
発熱量、△θ＝発熱センサーと流体の温度差） なお、発熱センサーの温度とは、発熱センサーの表面温
度であるが、ごく細い加熱細線を用いる場合は同センサ
ーの平均温度であってもよい。また、流体の温度は別の
センサーで計測してもよいし、本発明に利用する測温作
用も有する発熱センサーを電流操作することによって単
なる測温素子として使用し、流体の温度を計測してもよ
い。熱伝導率が既知の流体としては純水などがあげられ
るがこれらはどのような温度制御を行っても流体中に温
度分布がない状態とは言えずある程度の測定誤差に結び
つく。測定精度に高度な精度を求めない場合はこれらの
流体を熱伝導率が既知の流体として利用してもかまわな
いが、理想的には流体中に温度分布のないことが保証で
きるか、もしくは、熱伝導率が実用上温度に依存しない
と仮定できる流体であることが望ましい。前者の代表例
として過冷却状態の純水から一瞬にして形成される微細
純氷晶が純水中に均一分散する氷晶スラリーの系、後者
としてはグリセリン、がそれぞれ上げられる。上記純氷
晶スラリーの製造法は以下の手順による。純水を極低速
で冷却し続けると、純水は０℃以下の氷点下になっても
結晶化せず液体の状態を維持する。過冷却と称されるこ
の状態にある水に何等かの刺激が加わると、一定の部分
が一瞬にして微細氷晶に変化し、残存する０℃の水中に
均一分散したシャーベット状の氷晶スラリーとなる。過
冷却状態からの離脱によって形成された氷晶すラリー中
の温度分布はその直後において均一となり、かつ正確に
０℃を示し、理想的な校正用測定環境が得られる。In order to achieve the above object, the present invention uses the unsteady thin wire heating method to obtain the thermal conductivity of a fluid or solid. Arranges a heat generation sensor that is in thermal contact with a fluid or solid and has a heat generation effect and can measure its own temperature to cause the heat generation sensor to generate heat, and measures the unsteady change in temperature of the heat generation sensor itself over time. Then, the correlation between the logarithmic value of the same measurement time measured from the start of heat generation and the temperature is obtained, and the correction time of the actual measurement time resulting from the measurement processing time of the measuring device showing the correlation in which this relationship matches the theoretical value is numerically calculated. The thermal conductivity of the fluid or solid is measured as determined by the method. The temperature to be measured unsteadily in determining the correction time is the difference between the temperature of the fluid or solid and the temperature of the heat generation sensor, and a uniform temperature (0 ° C) can be easily and surely realized as a fluid whose thermal conductivity is known. A mixture (slurry) of crystals and pure water, or glycerin whose temperature dependence of thermal conductivity is practically negligible was used. Also, in carrying out the method for measuring thermal conductivity,
The thermal conductivity is calculated by the following formula by substituting the correction value resulting from the measurement processing time of the measuring device. (Λ = thermal conductivity, t0 = measurement time, t = correction time, Q =
Heat generation amount, Δθ = temperature difference between the heat generation sensor and the fluid) The temperature of the heat generation sensor is the surface temperature of the heat generation sensor, but may be the average temperature of the heat generation sensor when a very thin heating wire is used. . Further, the temperature of the fluid may be measured by another sensor, or the heat generation sensor used in the present invention, which also has a temperature measuring action, is used as a simple temperature measuring element by operating the current to measure the temperature of the fluid. Good. Pure water and the like are examples of fluids having a known thermal conductivity, but no matter what temperature control is performed, it cannot be said that the fluid has no temperature distribution, which leads to some measurement error. These fluids may be used as fluids with known thermal conductivity if a high degree of accuracy is not required, but ideally it can be guaranteed that there is no temperature distribution in the fluid, or It is desirable to use a fluid whose thermal conductivity can be assumed to be practically independent of temperature. As a typical example of the former, an ice crystal slurry system in which fine pure ice crystals formed in a moment from supercooled pure water are uniformly dispersed in pure water, and the latter is glycerin, respectively. The pure ice crystal slurry is produced by the following procedure. If the pure water is cooled at an extremely low speed, the pure water does not crystallize even if the freezing point is below 0 ° C. and maintains a liquid state. When some kind of stimulus is applied to water in this state called supercooling, a certain part instantly changes into fine ice crystals, and sherbet-like ice crystal slurry uniformly dispersed in the remaining 0 ° C water. Becomes The temperature distribution in the ice crystal rally formed by the separation from the supercooled state is uniform immediately after that and shows 0 ° C. accurately, so that an ideal measurement environment for calibration can be obtained.
【０００５】[0005]
【作用】発熱作用を有するとともに自らの温度を計測可
能な発熱センサーを熱伝導率が既知の流体もしくは固体
中に配置し、該発熱センサーを発熱せしめ、発熱センサ
ー温度の非定常変化を計測し、実測見かけ時間と温度変
化の相関関係を求める。そして、以上のようにして求め
た相関関係が直線的な相関を示すような補正時間を数値
的手法により求め、測定装置の測定処理時間に起因する
補正時間を決定する。こうして決定した補正時間を利用
し、発熱センサーを流体もしくは固体と熱的に接触さ
せ、非定常細線加熱法を利用して流体もしくは固体の熱
伝導率を高精度で求める。[Function] A heat-generating sensor having a heat-generating function and capable of measuring its own temperature is arranged in a fluid or a solid whose thermal conductivity is known, the heat-generating sensor is caused to generate heat, and an unsteady change in temperature of the heat-generating sensor is measured. Calculate the correlation between the measured apparent time and the temperature change. Then, the correction time such that the correlation obtained as described above shows a linear correlation is obtained by a numerical method, and the correction time due to the measurement processing time of the measuring device is determined. Using the correction time thus determined, the heat generation sensor is brought into thermal contact with the fluid or the solid, and the thermal conductivity of the fluid or the solid is obtained with high accuracy using the unsteady thin wire heating method.
【０００６】[0006]
【実施例】図１は本発明方法を実施するための測定装置
の一例を示している。被測定流体ｆが入った流体槽１の
内側に線状の発熱センサー２が配置してある。発熱セン
サー２は、例えば白金などの金属細線で構成される。セ
ンサー２の周囲の流体の温度分布などが均一となるよう
に、発熱センサー２は鉛直に配置する。発熱センサー２
の両端にはそれぞれ２本づつのリード線３が接続してあ
る。これらリード線３は電流源４と電圧計５に接続さ
れ、電流源８と電圧計９は制御装置６で制御される構成
になっている。以上のような測定装置において、発熱セ
ンサー２に電流を供給して発熱せしめ、発熱開始から温
度の上昇変化が生じている非定常状態において流体ｆの
温度と発熱センサー２自体の温度を計測し、両者の温度
差Δθを求めてその温度差Δθの経時変化から（１）式
を用いて流体の熱伝導率λを求める。なお、発熱センサ
ー２の温度は発熱センサーとして用いた金属細線の抵抗
値の変化から求めることができ、流体ｆの温度は図示し
ない測温センサーを流体中に設置して求めることができ
る。また、発熱センサー２の利用方法としては、リード
線３を介して適切な電流を流して発熱センサー２を発熱
させながら同時に発熱センサー２の両端の電圧計測値か
ら抵抗値を求め、予め決められた換算式を用いて温度を
算出する発熱体センサーとして用いる他、発熱センサー
２の発熱量が充分に小さく実質的に無視できる程度の微
小電流を供給してその時の電圧値を求めて流体ｆの温度
を測定するようにして単なる測温センサーとして用いる
こともできる。このように、一本の発熱センサー２によ
って流体ｆとセンサーの発熱温度の両方を求めて両者の
温度差Δθを計測することも可能である。FIG. 1 shows an example of a measuring apparatus for carrying out the method of the present invention. A linear heat generation sensor 2 is arranged inside a fluid tank 1 containing a fluid to be measured f. The heat generation sensor 2 is composed of a fine metal wire such as platinum. The heat generation sensor 2 is arranged vertically so that the temperature distribution of the fluid around the sensor 2 becomes uniform. Fever sensor 2
Two lead wires 3 are connected to both ends of each. These lead wires 3 are connected to the current source 4 and the voltmeter 5, and the current source 8 and the voltmeter 9 are controlled by the controller 6. In the measuring device as described above, an electric current is supplied to the heat generation sensor 2 to generate heat, and the temperature of the fluid f and the temperature of the heat generation sensor 2 itself are measured in an unsteady state in which a temperature rise change occurs from the start of heat generation, The temperature difference Δθ between the two is obtained, and the thermal conductivity λ of the fluid is obtained from the change with time of the temperature difference Δθ using the equation (1). The temperature of the heat generation sensor 2 can be obtained from the change in the resistance value of the thin metal wire used as the heat generation sensor, and the temperature of the fluid f can be obtained by installing a temperature measuring sensor (not shown) in the fluid. Further, as a method of using the heat generation sensor 2, a predetermined value is determined by obtaining a resistance value from a voltage measurement value at both ends of the heat generation sensor 2 while simultaneously causing an appropriate current to flow through the lead wire 3 to cause the heat generation sensor 2 to generate heat. In addition to being used as a heating element sensor for calculating the temperature using a conversion formula, the heating value of the fluid f is calculated by supplying a minute current whose heating value of the heating sensor 2 is sufficiently small and can be ignored. Can also be used as a mere temperature measuring sensor. In this way, it is possible to obtain both the fluid f and the heat generation temperature of the sensor with one heat generation sensor 2 and measure the temperature difference Δθ between the two.
【０００７】以下、実験例を基にして本発明の実施例を
説明する。 実施例１ 先ず、熱伝導率が既知の流体で均一温度に保たれた純水
中に発熱センサーを配置し、センサーを発熱させて温度
の非定常変化を経時的に計測し実測された見かけの時間
と同温度変化の関係が直線的な相関を示すような補正時
間ｔを数値的手法により求めた。ここで、実測された見
かけの時間ｔ0と真の時間ｔ0＋ｔを用いて（１）式を書
き直すと以下のようになる。 （λ＝熱伝導率、ｔ0＝実測された見かけの時間、ｔ＝
補正時間、Ｑ＝発熱量、△θ＝センサーと流体との温度
差） 式（２）において、例えば加熱細線が直径０.０５ｍ
ｍ、長さ１００ｍｍの白金線であり、発熱量を一定と
し、熱伝導率が既知である流体を用いれば、ｔ以外はす
べて実測可能であることからｔが求められることが分か
る。ｔは測定システムの電源や電圧計の処理時間、応答
時間その他に起因する時間の遅れであり、実測される見
かけの時間ｔ0 を補正するものである。発熱開始直後か
ら発熱センサーの温度を０. ２秒間隔で計測し、ｔ0 と
Δθを計測した。この測定を熱伝導率が既知の流体中で
おこない、測定値が理論的な直線と一致するように補正
時間ｔを（２）式を用いて数値的に算出した。図２は０
〜２５℃の純水中において実測される見かけの時間と温
度差から式（２）を用いて算出される補正時間ｔを測定
したもので、理論的直線の近傍に分布しており、この平
均から補正時間ｔは８５. ４±４. ７ｍｓｅｃであるこ
とが求められた。Hereinafter, examples of the present invention will be described based on experimental examples. Example 1 First, an exothermic sensor was placed in pure water kept at a uniform temperature with a fluid having a known thermal conductivity, the sensor was caused to generate heat, and an unsteady change in temperature was measured over time to obtain an apparent measurement. The correction time t such that the relationship between the time and the temperature change shows a linear correlation was obtained by a numerical method. Here, when the equation (1) is rewritten using the measured apparent time t0 and true time t0 + t, it becomes as follows. (Λ = thermal conductivity, t0 = measured apparent time, t =
Correction time, Q = heat value, Δθ = temperature difference between sensor and fluid) In the formula (2), for example, the heating thin wire has a diameter of 0.05 m.
It can be seen that when a fluid of m and a length of 100 mm, which has a constant calorific value and a known thermal conductivity, is used, it is possible to measure t except t, so that t can be obtained. t is a time delay due to the processing time of the power supply of the measurement system and the voltmeter, the response time, and the like, and corrects the apparent time t0 actually measured. Immediately after the start of heat generation, the temperature of the heat generation sensor was measured at intervals of 0.2 seconds, and t0 and Δθ were measured. This measurement was carried out in a fluid having a known thermal conductivity, and the correction time t was numerically calculated using the equation (2) so that the measured value would agree with the theoretical straight line. 2 is 0
The correction time t calculated using equation (2) from the apparent time and temperature difference actually measured in pure water at -25 ° C is measured, and it is distributed in the vicinity of the theoretical line. Therefore, the correction time t was required to be 85.4 ± 4.7 msec.
【０００８】実施例２ 直径０. ０５ｍｍ、長さ１００ｍｍの発熱センサーを発
熱量５Ｗ／ｍで発熱させ、流体は純水を使用して熱伝導
率を測定した。図３は、式（１）を用いて補正時間を利
用せずに算出した熱伝導率と温度の関係を示す。一方、
図４は上記補正時間８５. ４ｍｓｅｃを利用して、式
（２）によって熱伝導率を算出した結果を示す。図４の
ごとく実測値と文献値はよく一致した。また、流体とし
てグリセリン３０％水溶液を用いて同様の条件で測定し
た結果からも補正時間の利用によって文献値とよく一致
するという結果が得られた（図５）。更に、同様の方法
でグリセリン濃度０％から１００％までについて熱伝導
率を流体温度０℃の場合と２０℃の場合にわけて算出し
た結果が図６と図７である。○は実測値で、●は文献値
であり、両者もよく一致している。Example 2 A heat generation sensor having a diameter of 0.05 mm and a length of 100 mm was caused to generate heat with a heat generation amount of 5 W / m, and pure water was used as a fluid to measure the thermal conductivity. FIG. 3 shows the relationship between the thermal conductivity and the temperature calculated using Equation (1) without using the correction time. on the other hand,
FIG. 4 shows the result of calculating the thermal conductivity by the equation (2) using the correction time of 85.4 msec. As shown in FIG. 4, the measured values and the literature values were in good agreement. Further, from the results of measurement under the same conditions using a 30% aqueous glycerin solution as a fluid, it was found that the results were in good agreement with the literature values by using the correction time (FIG. 5). Further, FIG. 6 and FIG. 7 show the results obtained by calculating the thermal conductivity for the glycerin concentration of 0% to 100% separately for the fluid temperature of 0 ° C. and the fluid temperature of 20 ° C. by the same method. ○ is the measured value, ● is the literature value, and both agree well.
【０００９】なお、本発明において、発熱センサーが同
一でも測定システムのハードやソフトのどちらか、もし
くは両方に変更があった場合は補正時間も異なってくる
ので、新たに補正時間の設定操作をやり直さなければな
らない。In the present invention, even if the heat generation sensor is the same, if the hardware or software of the measurement system or both of them are changed, the correction time will be different. Therefore, the correction time setting operation must be performed again. There must be.
【００１０】[0010]
１．従来流体の熱伝導率は測定システムの測定処理時間
に起因する測定誤差の検討がされていなかったが、本発
明により測定システム毎の補正値をもとめることが可能
になり、正確な熱伝導率の測定を実施することが可能と
なった。 ２．本発明では測定システムの誤差を補正することによ
り得られる直線が測定開始時から直線で得られ、人為的
判断が介在することがなく、誰が測定しても正確な測定
値を得られる。また該補正のため、測定を対流の影響を
受けない時間内に確実に終了させられ、測定所要時間の
大幅な短縮が可能となった。 ３．本発明方法によれば、発熱センサーを０. ０５ｍｍ
以上に設定したとしても、測定システム自体の処理時間
に起因する誤差は補正されているので、残る問題は発熱
センサー自体の物性に起因する誤差のみとなり、従来の
方法から比較すると、その測定結果の正確性は飛躍的に
向上する。1. Conventionally, the thermal conductivity of the fluid has not been examined for the measurement error due to the measurement processing time of the measurement system, but the present invention makes it possible to obtain a correction value for each measurement system, and to obtain an accurate thermal conductivity. It has become possible to carry out measurements. 2. In the present invention, a straight line obtained by correcting the error of the measurement system is obtained as a straight line from the start of measurement, and an accurate measurement value can be obtained regardless of who measures it, without any intervention of human judgment. Further, because of the correction, the measurement can be surely completed within the time not affected by the convection, and the time required for the measurement can be greatly shortened. 3. According to the method of the present invention, the heat sensor is set to 0.05 mm.
Even with the above settings, the error due to the processing time of the measurement system itself has been corrected, so the only remaining problem is the error due to the physical properties of the heat generation sensor itself. Accuracy is dramatically improved.
【図１】本発明方法を実施するための測定装置の一例を
示つ図面FIG. 1 is a drawing showing an example of a measuring apparatus for carrying out the method of the present invention.
【図２】純水を利用して発熱センサーと流体との温度差
と補正時間の関係を求めた結果を示すグラフ（実験１）FIG. 2 is a graph showing the results of obtaining the relationship between the temperature difference between the heat generation sensor and the fluid and the correction time using pure water (Experiment 1).
【図３】補正時間を算入しないで純水において発熱セン
サーと流体との温度差と熱伝導率の関係を示したグラフ
（実験２）FIG. 3 is a graph showing the relationship between the temperature difference between the heat generation sensor and the fluid and the thermal conductivity in pure water without including the correction time (Experiment 2).
【図４】補正時間を算入して純水において発熱センサー
と流体との温度差と熱伝導率の関係を示したグラフ（実
験２）FIG. 4 is a graph showing the relationship between the thermal conductivity and the temperature difference between the heat generation sensor and the fluid in pure water, including the correction time (Experiment 2).
【図５】補正時間を算入してグリセリン３０％水溶液に
おいて発熱センサーと流体との温度差と熱伝導率の関係
を示したグラフ（実験２）FIG. 5 is a graph showing the relationship between the temperature difference between the heat generation sensor and the fluid and the thermal conductivity in a 30% aqueous glycerin solution including the correction time (Experiment 2).
【図６】流体温度０℃、濃度０〜１００％のグリセリン
水溶液において発熱センサーと流体との温度差と熱伝導
率の関係を示したグラフ（実験２）FIG. 6 is a graph showing the relationship between the thermal conductivity and the temperature difference between the heat generation sensor and the fluid in a glycerin aqueous solution having a fluid temperature of 0 ° C. and a concentration of 0 to 100% (Experiment 2).
【図７】流体温度２０℃、濃度０〜１００％のグリセリ
ン水溶液において発熱センサーと流体との温度差と熱伝
導率の関係を示したグラフ（実験２）FIG. 7 is a graph showing the relationship between the thermal conductivity and the temperature difference between the heat generation sensor and the fluid in an aqueous glycerin solution having a fluid temperature of 20 ° C. and a concentration of 0 to 100% (Experiment 2).
２ 発熱センサー 2 fever sensor
Claims (4)
は固体の熱伝導率を求めるにあたり、熱伝導率既知の流
体もしくは固体中に流体もしくは固体と熱的に接触し、
発熱作用を有するとともに自らの温度を計測可能な発熱
センサーを配置して該発熱センサーを発熱せしめ、該発
熱センサー自体の温度の非定常変化を経時的に計測し、
発熱開始から計測した同計測時間の対数値と該温度の相
関関係を求め、この関係が理論値と一致するよう測定装
置の測定処理時間に起因する実測時間の補正時間を数値
的手法により求めることを特徴とする流体もしくは固体
の熱伝導率の測定方法。1. When obtaining the thermal conductivity of a fluid or solid by using the unsteady thin wire heating method, the fluid or solid of known thermal conductivity is brought into thermal contact with the fluid or solid,
Arrange a heat generation sensor that has a heat generation effect and can measure its own temperature to cause the heat generation sensor to generate heat, and measure the unsteady change in the temperature of the heat generation sensor itself over time,
Obtain the correlation between the logarithmic value of the same measurement time measured from the start of heat generation and the temperature, and obtain the correction time of the actual measurement time resulting from the measurement processing time of the measuring device by a numerical method so that this relationship matches the theoretical value. A method for measuring the thermal conductivity of a fluid or a solid characterized by.
が流体もしくは固体の代表温度と発熱センサーの温度と
の温度差である請求項１記載の熱伝導率の測定方法。2. The method for measuring thermal conductivity according to claim 1, wherein the temperature measured for obtaining the correction time is the temperature difference between the representative temperature of the fluid or solid and the temperature of the heat generation sensor.
導率既知の流体が純氷晶と純水の混合物もしくはグリセ
リンである請求項１または２記載の熱伝導率の測定方
法。3. The method for measuring thermal conductivity according to claim 1, wherein the fluid having a known thermal conductivity used for obtaining the correction time is a mixture of pure ice crystals and pure water or glycerin.
実施するにあたって、熱伝導率を求める式が測定装置の
測定処理時間に起因する補正値を含む次式である熱伝導
率の測定方法。 （λ＝流体の熱伝導率、ｔ0 ＝実測された見かけの時
間、ｔ＝補正時間、Ｑ＝発熱量、△θ＝発熱センサー温
度と流体温度の差）4. In carrying out the method for measuring thermal conductivity according to any one of claims 1 to 3, the equation for calculating the thermal conductivity is the following equation including a correction value resulting from the measurement processing time of the measuring device. Measuring method. (Λ = heat conductivity of fluid, t0 = measured apparent time, t = correction time, Q = heat amount, Δθ = difference between heat sensor temperature and fluid temperature)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5028094A JP2537744B2 (en) | 1993-02-17 | 1993-02-17 | Measuring method of thermal conductivity |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5028094A JP2537744B2 (en) | 1993-02-17 | 1993-02-17 | Measuring method of thermal conductivity |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06242034A true JPH06242034A (en) | 1994-09-02 |
| JP2537744B2 JP2537744B2 (en) | 1996-09-25 |
Family
ID=12239205
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5028094A Expired - Fee Related JP2537744B2 (en) | 1993-02-17 | 1993-02-17 | Measuring method of thermal conductivity |
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| Country | Link |
|---|---|
| JP (1) | JP2537744B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005156315A (en) * | 2003-11-25 | 2005-06-16 | Univ Waseda | Thermal conductivity measuring device, system, and method |
| CN104040327A (en) * | 2011-12-23 | 2014-09-10 | 西格里碳素欧洲公司 | Method for measuring thermal conductivity |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5059074A (en) * | 1973-09-26 | 1975-05-22 |
-
1993
- 1993-02-17 JP JP5028094A patent/JP2537744B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5059074A (en) * | 1973-09-26 | 1975-05-22 |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005156315A (en) * | 2003-11-25 | 2005-06-16 | Univ Waseda | Thermal conductivity measuring device, system, and method |
| CN104040327A (en) * | 2011-12-23 | 2014-09-10 | 西格里碳素欧洲公司 | Method for measuring thermal conductivity |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2537744B2 (en) | 1996-09-25 |
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