WO2011068293A1 - Apparatus for measuring thermal diffusivity in a nanofluid - Google Patents

Apparatus for measuring thermal diffusivity in a nanofluid Download PDF

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Publication number
WO2011068293A1
WO2011068293A1 PCT/KR2010/003768 KR2010003768W WO2011068293A1 WO 2011068293 A1 WO2011068293 A1 WO 2011068293A1 KR 2010003768 W KR2010003768 W KR 2010003768W WO 2011068293 A1 WO2011068293 A1 WO 2011068293A1
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nanofluid
heat
heating wire
loop
voltage difference
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PCT/KR2010/003768
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French (fr)
Korean (ko)
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최철
오제명
이신표
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한국전력공사
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/14—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature
    • G01N27/18—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature caused by changes in the thermal conductivity of a surrounding material to be tested
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/18—Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
    • B82B3/00—Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/08—Materials not undergoing a change of physical state when used
    • C09K5/10—Liquid materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
    • G01K7/20—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit

Definitions

  • the present invention relates to a thermal diffusivity measuring apparatus, and more particularly, to a thermal diffusivity measuring apparatus of a nanofluid for measuring heat diffused inside a nanofluid using a voltage difference generated inside the bridge circuit.
  • the fluid is a generic term for a liquid or gas that can be freely deformed due to its undefined shape, and is used in various fields such as an air conditioning system and a cooling device.
  • Nanofluids are mixed fluids that enhance the heat transfer and thermal diffusion performance of fluids by adding nanosized solid particles such as metals, oxides, ceramics or nonmetals with high thermal conductivity to liquids such as water, ethylene glycol and oils. Nanofluid is used as a heat exchange or heat transport device that exchanges heat from a high temperature to a low temperature in a heat transfer medium or a heat removal device because of its excellent heat transfer characteristics.
  • nanofluids Since the performance of such nanofluids is determined by thermal conductivity and thermal diffusivity, the usefulness of nanofluids is verified by comparing nanofluid thermal conductivity and thermal diffusion before and after solid particles are added.
  • the method of measuring the thermal conductivity and thermal diffusion of the nanofluid is an abnormal heat wire method that can simultaneously measure the thermal conductivity and thermal diffusion of the nanofluid.
  • a thin hot wire sensor in which a resistance value changes with a change in temperature is inserted in a direction of gravity inside a fluid to be measured.
  • the temperature of the hot wire sensor itself is increased, and the temperature of the fluid into which the hot wire sensor is inserted is increased.
  • the heat conduction effect of the fluid inserted into the heat sensor is good, since most of the heat generated by the heat sensor is transferred to the fluid to increase the temperature of the heat sensor is small, the increase amount of the resistance of the heat sensor is small.
  • the heat conduction effect of the fluid is good when the amount of increase of the resistance of the heat sensor is good, and the heat conduction effect of the fluid is not good when the increase of the resistance of the heat sensor is large.
  • Embodiments of the present invention reduce the error between the thermal diffusion rate of the nanofluid and the actual thermal diffusion rate of the nanofluid calculated by the experimental data, which occurs in the abnormal heat ray method that measures the thermal diffusivity inside the nanofluid with a single heat ray sensor.
  • An object of the present invention is to provide an apparatus for measuring thermal diffusion rate of nanofluid.
  • the heating wire is inserted into the interior of the nano-fluid to receive power to apply heat;
  • a bridge circuit in which a portion of the heating wire is spaced apart from the heating wire to generate a voltage difference therein based on a resistance value that changes in response to the heat diffused from the heating wire;
  • an amplification unit configured to receive the voltage difference of the bridge circuit and amplify the voltage difference to output the voltage difference.
  • the bridge circuit may further include: a heat sensing unit configured to change a resistance value corresponding to heat diffused from the heating wire; A first loop having a first fixed resistor connected in series; And a second loop in which a second fixed resistor and a variable resistor are connected in series, and the first loop and the second loop may be connected in parallel.
  • the heat sensing unit may be inserted into the nanofluid so as to correspond to the heating wire.
  • the heat sensing unit may increase a resistance value in proportion to heat diffused from the heating wire.
  • the voltage difference between the first loop and the second loop may be increased in proportion to the resistance of the heat sensing unit.
  • Embodiments of the present invention by using a bridge circuit that measures the internal temperature of the nano-fluid of the heating portion and the heat generating portion a certain distance away from the heat generating portion, the heat diffusion to the nano-fluid accurately measure the heat diffusion inside the nano-fluid Thus, it is possible to reduce the error between the thermal diffusion rate of the nanofluid and the actual thermal diffusion rate of the nanofluid calculated by the experimental data.
  • FIG. 1 is a schematic diagram showing an apparatus for measuring thermal diffusivity of a nanofluid according to an embodiment of the present invention.
  • Figure 2 is a voltage change data of the engine oil and glycerin obtained by the thermal diffusivity measuring device of the nanofluid.
  • 3 is a graph of a straight line in which the experimental result of the engine oil is changed into a straight line through curve fitting.
  • heating wire 111 first power supply unit
  • first node 122 thermal sensing unit
  • first fixed resistor 124 second loop
  • variable resistance 130 amplifier
  • FIG. 1 is a schematic diagram showing an apparatus 100 for measuring the thermal diffusion rate of a nanofluid according to an embodiment of the present invention.
  • the apparatus 100 for measuring heat diffusion rate of a nanofluid includes a heating wire 110, a bridge circuit 120, and an amplifier 130.
  • the heating wire 110 is for applying heat to the interior of the nanofluid 11 accommodated in the experiment container 10.
  • the heating wire 110 is inserted into the nanofluid 11 and the electrical energy supplied from the first power supply 111 is converted into thermal energy. To generate heat.
  • the heating wire 110 may be made of a platinum wire or tungsten wire having good thermal conductivity.
  • the first power supply 111 is for supplying power to the heating wire 110 and is connected to the heating wire 110.
  • the thermal diffusion rate measuring apparatus 100 is generated from the switch 112 and the heating wire 110 inserted into the nano-fluid 11 to selectively cut off the power applied to the heating wire 110.
  • a calorimetry resistor 113 connected in series with the heating wire 110 may be further included.
  • the bridge circuit 120 detects heat diffused in the nanofluid 11 and includes a first loop 121 and a second loop 124. In addition, the first loop 121 and the second loop 124 are connected in parallel.
  • the heat sensing unit 122 and the first fixed resistor 123 are connected in series.
  • the heat detection unit 122 has a resistance value corresponding to heat diffused from the heating wire 110, and is inserted into the nanofluid 11 so as to be parallel to the heating wire 110. In addition, the resistance value increases in proportion to the heat diffused into the heating wire 110 inside the nanofluid 11.
  • the heat detection unit 122 may be formed in a shape corresponding to the heating wire 110, in order to receive the heat generated from the heating wire 110 effectively. Further, it may be formed of a platinum wire or tungsten wire having good thermal conductivity.
  • the second fixed resistor 125 and the variable resistor 126 are connected in series.
  • the variable resistor 126 has a voltage value corresponding to a resistance value according to a basic temperature of the nanofluid 11 when the heat sensing unit 122 is inserted into the nanofluid 11.
  • the voltage across the first node 121a between the heat sensing unit 122 and the first fixed resistor 123 of the first loop 121 and the second fixed resistor of the second loop 124 ( The voltage applied to the second node 124a between the 125 and the variable resistor 126 is equalized to prevent current from flowing to the amplifier 130.
  • the voltage applied to the first node 121a and the voltage applied to the second node 124a are balanced if the temperature of the nanofluid 11 is not changed. However, when the temperature of the nanofluid 11 is changed by the heating wire 110, a difference occurs in the voltage applied to the first node 121a and the voltage applied to the second node 124a, and thus the amplification unit 130 Current flows through
  • the amplifier 130 is for amplifying the voltage difference generated in the bridge circuit 120, one side is connected to the bridge circuit 120, the voltage applied to the first node 121a and the second node 124a It is amplified by receiving the non-inverting terminal and the inverting terminal, and the other side is connected to a separate display member, that is, a data recorder 12 or an oscilloscope and outputs a temperature value.
  • the thermal diffusivity measuring apparatus 100 may further include a second power supply unit 140 for supplying power to the bridge circuit 120 and the amplification unit 130.
  • the thermal diffusivity measuring apparatus 100 further includes a protective case (not shown) for fixing the position of the heating wire 110 and the heat sensing unit 122 inserted into the nanofluid 11 and protecting other devices. It may include.
  • the protective case may be formed in a hollow rectangular parallelepiped shape.
  • the protective case may expose the heating wire 110 and the heat sensing unit 122 to a hollow portion of the protective case, thereby fixing the positions of the heating wire 110 and the heat sensing unit 122.
  • other device parts connected to the heating wire 110 and the heat sensing unit 122 may be inserted into the protective case to prevent the other device parts from being exposed to the nanofluid.
  • Equation 1 The increase in the internal temperature of the nanofluid 11 at a distance r from the heating wire 110 is expressed by Equation 1 below.
  • Equation 2 Equation 2
  • the measurement measured using the thermal diffusivity measuring apparatus 100 according to the embodiment of the present invention only uses data up to approximately 15 seconds.
  • the heat sensing unit 122 has a resistance value of approximately 12.963 ⁇ in the nanofluid 11, and the first fixed resistor 123 has a resistance value of 2k ⁇ .
  • the second fixed resistor 125 has a resistance value of 10 k ⁇ , and the variable resistor 126 is adjusted in the resistance value range of 1 k ⁇ .
  • the resistance value of the variable resistor 126 in the balanced state of the bridge circuit 120 is 64.815 ⁇ .
  • a characteristic of the bridge circuit 120 is that the resistance value of the first fixed resistor 123 is much larger than the resistance value of the heat sensing unit 122.
  • the change in the resistance value according to the temperature rise is shown in Equation 4 below.
  • R t is the resistance value of the heat sensing unit 122
  • R t0 is the original resistance value of the heat sensing unit 122.
  • the temperature that changes for 15 seconds even in the engine oil that the temperature rise is large is about 1 °C.
  • the current flowing in the first loop 121 including the heat sensing unit 122 becomes 7.4515 mA. Therefore, when the magnitude of the resistance value changes small, almost constant current flows through the bridge circuit 120. Therefore, when the resistance value of the heat sensing unit 122 increases, the voltage applied to the first node 121 increases, and as a result, the voltage difference between the first loop 121 and the second loop 124 increases. .
  • the change amount of the voltage difference and the change amount of temperature between the first loop 121 and the second loop 124 are expressed by Equation 5 below.
  • Equation 3 is a constant such as the mass of the nanofluid 11, the thermal diffusion rate, and the interval between the heating wire 110 and the heat sensing unit 122. In consideration of Equation 6 below.
  • the internal voltage difference rise time data of the bridge circuit 120 may be curved by a linear function through an appropriate conversion process.
  • the C 2 with the information of thermal diffusivity in the [Equation 6], wherein the modification to a linear function in equation 8] A represents a C 2.
  • the voltage change data obtained by the thermal diffusion rate measuring apparatus 100 of the nanofluid shown in FIG. 2 is displayed in a straight line through curve fitting to obtain the slope of the straight line.

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Abstract

Disclosed is an apparatus for measuring thermal diffusivity in a nanofluid. The apparatus for measuring thermal diffusivity in a nanofluid according to one embodiment of the present invention comprises: a heating wire for receiving electric power to apply heat to a nanofluid; a bridge circuit, a portion of which is disposed at a predetermined distance from the heating wire, and in which a voltage difference is formed in accordance with a change in a resistance value corresponding to the heat diffused from the heating wire; and an amplifier for receiving the voltage difference of the bridge circuit, and amplifying and outputting the voltage difference.

Description

나노유체의 열확산율 측정장치Thermal diffusion rate measuring device of nanofluid
본 발명은 열확산율 측정장치에 관한 것으로, 더 상세하게는 브릿지 회로의 내부에서 발생되는 전압차를 사용하여 나노유체의 내부에서 확산되는 열을 측정하는 나노유체의 열확산율 측정장치에 관한 것이다.The present invention relates to a thermal diffusivity measuring apparatus, and more particularly, to a thermal diffusivity measuring apparatus of a nanofluid for measuring heat diffused inside a nanofluid using a voltage difference generated inside the bridge circuit.
일반적으로, 유체는 형상이 정해지지 않아 변형이 쉽고 자유로이 흐를 수 있는 액체 또는 기체를 총칭하고, 공기조화 시스템 및 냉각장치 등의 다양한 분야에 사용된다. In general, the fluid is a generic term for a liquid or gas that can be freely deformed due to its undefined shape, and is used in various fields such as an air conditioning system and a cooling device.
나노유체는 물, 에틸렌글리콜 및 오일 등의 액체에 열전도가 높은 금속, 산화물, 세라믹 또는 비금속 등과 같은 나노 크기의 고상 입자를 첨가하여 유체의 열전달 및 열확산 성능을 높인 혼합유체이다. 나노유체는 뛰어난 열전달 특성으로 인해 열전달매체 또는 열제거장치 등에서 고온에서 저온으로 열을 교환해주는 열 교환 또는 열 수송용 소자로 사용된다.Nanofluids are mixed fluids that enhance the heat transfer and thermal diffusion performance of fluids by adding nanosized solid particles such as metals, oxides, ceramics or nonmetals with high thermal conductivity to liquids such as water, ethylene glycol and oils. Nanofluid is used as a heat exchange or heat transport device that exchanges heat from a high temperature to a low temperature in a heat transfer medium or a heat removal device because of its excellent heat transfer characteristics.
이와 같은 나노유체의 성능은 열전도 및 열확산 정도에 의해 결정되기 때문에, 고상 입자가 첨가되기 전과 후의 나노유체 열전도 및 열확산을 비교함으로써, 나노유체의 유용성을 검증하고 있다.Since the performance of such nanofluids is determined by thermal conductivity and thermal diffusivity, the usefulness of nanofluids is verified by comparing nanofluid thermal conductivity and thermal diffusion before and after solid particles are added.
한편, 일반적으로 나노유체의 열전도 및 열확산을 측정하는 방법으로는 나노유체의 열전도 및 열확산을 동시에 측정가능한 비정상 열선법이 있다.On the other hand, in general, the method of measuring the thermal conductivity and thermal diffusion of the nanofluid is an abnormal heat wire method that can simultaneously measure the thermal conductivity and thermal diffusion of the nanofluid.
비정상 열선법에 따르면, 온도의 변화에 따라 저항값이 변화되는 가느다란 열선센서가 측정 대상인 유체 내부에 중력방향으로 삽입된다. 그리고, 상기 열선센서에 순간적으로 전류가 흐르면, 상기 열선센서 자체의 온도가 상승 되고, 열선센서가 삽입된 유체의 온도가 상승 된다. 이때, 상기 열선센서가 삽입된 유체의 열전도 효과가 좋으면, 열선센서에 의해 발생 되는 열의 대부분은 유체 쪽으로 전달되어 열선센서의 온도상승이 작게 발생하므로, 열선센서 저항값의 증가량이 작다. 반면에, 상기 열선센서가 삽입된 유체의 열전도 효과가 좋지 않으면, 열선센서에 의해 발생 되는 열의 대부분은 열선센서에 축적되어 열선센서의 온도상승이 크게 발생하므로, 열선센서 저항값의 증가량이 커진다.According to the unsteady hot wire method, a thin hot wire sensor in which a resistance value changes with a change in temperature is inserted in a direction of gravity inside a fluid to be measured. When the current flows momentarily through the hot wire sensor, the temperature of the hot wire sensor itself is increased, and the temperature of the fluid into which the hot wire sensor is inserted is increased. At this time, if the heat conduction effect of the fluid inserted into the heat sensor is good, since most of the heat generated by the heat sensor is transferred to the fluid to increase the temperature of the heat sensor is small, the increase amount of the resistance of the heat sensor is small. On the other hand, if the heat conduction effect of the fluid inserted into the heat sensor is not good, most of the heat generated by the heat sensor is accumulated in the heat sensor, so that the temperature rise of the heat sensor is large, the increase in the heat sensor resistance value increases.
즉, 비정상 열선법에 있어서, 상기 열선센서 저항값의 증가량이 적으면 유체의 열전도 효과가 좋고, 열선센서 저항값의 증가량이 크면 유체의 열전도 효과가 좋지 못하다. That is, in the abnormal heat wire method, the heat conduction effect of the fluid is good when the amount of increase of the resistance of the heat sensor is good, and the heat conduction effect of the fluid is not good when the increase of the resistance of the heat sensor is large.
그러나, 이와 같이 유체 내부의 열확산율을 측정하는 상기 비정상 열선법은 하나의 열선센서를 사용하므로, 실험결과데이터에 의해 계산된 열확산율과 실제 나노유체의 열확산율간의 차이가 많이 발생한다는 문제점이 있었다.However, since the abnormal hot wire method that measures the heat diffusion rate in the fluid as described above uses a single heat sensor, there is a problem in that a large difference between the heat diffusion rate calculated by the experimental data and the actual heat diffusion rate of the nanofluid occurs. .
본 발명의 실시예들은 하나의 열선센서로 나노유체 내부의 열확산율을 측정하는 비정상열선법에서 발생하는, 실험결과데이터에 의해 계산되는 나노유체의 열확산율과 실제 나노유체의 열확산율의 오차를 줄인 나노유체의 열확산율 측정장치를 제공하는 것을 목적으로 한다.Embodiments of the present invention reduce the error between the thermal diffusion rate of the nanofluid and the actual thermal diffusion rate of the nanofluid calculated by the experimental data, which occurs in the abnormal heat ray method that measures the thermal diffusivity inside the nanofluid with a single heat ray sensor. An object of the present invention is to provide an apparatus for measuring thermal diffusion rate of nanofluid.
본 발명의 일측면에 따르면, 전원을 공급받아 나노유체의 내부에 삽입되어 열을 가하는 전열선; 상기 전열선으로부터 일부분이 소정간격 이격되도록 배치되어 상기 전열선으로부터 확산되는 열에 대응하여 변화되는 저항값에 근거하여 내부에 전압차가 발생되는 브릿지 회로; 및 상기 브릿지 회로의 상기 전압차를 전달받아 상기 전압차를 증폭하여 출력하는 증폭부;를 포함하는 나노유체의 열확산율 측정장치가 제공될 수 있다.According to an aspect of the present invention, the heating wire is inserted into the interior of the nano-fluid to receive power to apply heat; A bridge circuit in which a portion of the heating wire is spaced apart from the heating wire to generate a voltage difference therein based on a resistance value that changes in response to the heat diffused from the heating wire; And an amplification unit configured to receive the voltage difference of the bridge circuit and amplify the voltage difference to output the voltage difference.
또한, 상기 브릿지 회로는 상기 전열선으로부터 확산되는 열에 대응하여 저항값이 변화되는 열감지부; 제 1 고정저항이 직렬로 연결되어 있는 제 1 루프; 및 제 2 고정저항과 가변저항이 직렬로 연결된 제 2 루프를 포함하고, 상기 제 1 루프 및 제 2 루프는 병렬로 연결될 수 있다.The bridge circuit may further include: a heat sensing unit configured to change a resistance value corresponding to heat diffused from the heating wire; A first loop having a first fixed resistor connected in series; And a second loop in which a second fixed resistor and a variable resistor are connected in series, and the first loop and the second loop may be connected in parallel.
또한, 상기 열감지부는 상기 전열선에 대응되도록, 상기 나노유체의 내부에 삽입될 수 있다. In addition, the heat sensing unit may be inserted into the nanofluid so as to correspond to the heating wire.
또한, 상기 열감지부는 상기 전열선으로부터 확산되는 열에 비례하여 저항값이 증가될 수 있다. In addition, the heat sensing unit may increase a resistance value in proportion to heat diffused from the heating wire.
또한, 상기 제 1 루프와 제 2 루프 사이의 상기 전압차는 상기 열감지부의 저항값에 비례하여 증가될 수 있다.In addition, the voltage difference between the first loop and the second loop may be increased in proportion to the resistance of the heat sensing unit.
본 발명의 실시예들은 나노유체에 열을 가하는 전열선과 열발생부에서 일정거리만큼 떨어진 부분의 나노유체의 내부온도를 측정하는 브릿지회로를 사용함으로써, 나노유체의 내부에 열이 확산 되는 것을 정확하게 측정하여, 실험결과 데이터에 의해 계산되는 나노유체의 열확산율과 실제 나노유체의 열확산율의 오차를 줄일 수 있다.Embodiments of the present invention by using a bridge circuit that measures the internal temperature of the nano-fluid of the heating portion and the heat generating portion a certain distance away from the heat generating portion, the heat diffusion to the nano-fluid accurately measure the heat diffusion inside the nano-fluid Thus, it is possible to reduce the error between the thermal diffusion rate of the nanofluid and the actual thermal diffusion rate of the nanofluid calculated by the experimental data.
도 1은 본 발명의 실시예에 따른 나노유체의 열확산율 측정장치를 나타내는 개략도이다.1 is a schematic diagram showing an apparatus for measuring thermal diffusivity of a nanofluid according to an embodiment of the present invention.
도 2는 나노유체의 열확산율 측정장치에 의해 얻어진 엔진오일 및 글리세린의 전압변화 데이터이다.Figure 2 is a voltage change data of the engine oil and glycerin obtained by the thermal diffusivity measuring device of the nanofluid.
도 3은 엔진오일의 실험결과가 곡선맞춤을 통해 직선으로 변화된 직선의 그래프이다.3 is a graph of a straight line in which the experimental result of the engine oil is changed into a straight line through curve fitting.
도 4는 글리세린의 실험결과가 곡선맞춤을 통해 직선으로 변화된 직선의 그래프이다.4 is a graph of a straight line in which the experimental result of glycerin is changed into a straight line through curve fitting.
<도면의 주요부분에 대한 부호의 설명><Description of the symbols for the main parts of the drawings>
10: 실험용기 11: 나노유체 10: Experimental container 11: Nanofluid
12: 데이터 기록계 100: 열확산율 측정장치 12: data recorder 100: thermal diffusivity measuring device
110: 전열선 111: 제 1 전원공급부 110: heating wire 111: first power supply unit
112: 스위치 113: 열량측정저항 112: switch 113: calorimetric resistance
120: 브릿지 회로 121: 제 1 루프 120: bridge circuit 121: first loop
121a: 제 1 노드 122: 열감지부 121a: first node 122: thermal sensing unit
123: 제 1 고정저항 124: 제 2 루프 123: first fixed resistor 124: second loop
124a: 제 2 노드 125: 제 2 고정저항 124a: second node 125: second fixed resistor
126: 가변저항 130: 증폭부 126: variable resistance 130: amplifier
140: 제 2 전원공급부 140: second power supply unit
이하, 첨부한 도면을 참조로 본 발명의 바람직한 실시예에 따른 나노유체의 열확산율 측정장치에 대해 상세하게 설명하기로 한다. Hereinafter, an apparatus for measuring thermal diffusivity of nanofluid according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
도 1은 본 발명의 실시예에 따른 나노유체의 열확산율 측정장치(100)를 나타내는 개략도이다. 1 is a schematic diagram showing an apparatus 100 for measuring the thermal diffusion rate of a nanofluid according to an embodiment of the present invention.
도 1을 참조하면, 본 발명의 실시예에 따른 나노유체의 열확산율 측정장치(100)는 전열선(110), 브릿지회로(120) 및 증폭부(130)를 포함한다.Referring to FIG. 1, the apparatus 100 for measuring heat diffusion rate of a nanofluid according to an exemplary embodiment of the present invention includes a heating wire 110, a bridge circuit 120, and an amplifier 130.
전열선(110)은 실험용기(10)에 수용된 나노유체(11)의 내부에 열을 가하기 위한 것으로, 나노유체(11) 내부에 삽입되며 제 1 전원공급부(111)로부터 공급되는 전기에너지를 열에너지로 전환시켜 열을 발생시킨다.The heating wire 110 is for applying heat to the interior of the nanofluid 11 accommodated in the experiment container 10. The heating wire 110 is inserted into the nanofluid 11 and the electrical energy supplied from the first power supply 111 is converted into thermal energy. To generate heat.
상기 전열선(110)은 열 전도성이 좋은 백금선 또는 텅스텐선 등으로 이루어질 수 있다.The heating wire 110 may be made of a platinum wire or tungsten wire having good thermal conductivity.
상기 제 1 전원공급부(111)는 전열선(110)에 전원을 공급하기 위한 것으로, 상기 전열선(110)에 연결된다.The first power supply 111 is for supplying power to the heating wire 110 and is connected to the heating wire 110.
또한, 상기 열확산율 측정장치(100)는 상기 전열선(110)으로 인가되는 전원을 선택적으로 차단할 수 있는 스위치(112)와 상기 나노유체(11)의 내부에 삽입된 상기 전열선(110)에서 발생되는 열량을 간접적으로 계산하기 위해, 상기 전열선(110)에 직렬로 연결되는 열량측정저항(113)을 더 포함할 수 있다.In addition, the thermal diffusion rate measuring apparatus 100 is generated from the switch 112 and the heating wire 110 inserted into the nano-fluid 11 to selectively cut off the power applied to the heating wire 110. In order to indirectly calculate the calorie value, a calorimetry resistor 113 connected in series with the heating wire 110 may be further included.
브릿지 회로(120)는 상기 나노유체(11) 내부에 확산되는 열을 감지하기 위한 것으로, 제 1 루프(121) 및 제 2 루프(124)를 포함한다. 또한, 상기 제 1 루프(121) 및 제 2 루프(124)는 병렬로 연결된다.The bridge circuit 120 detects heat diffused in the nanofluid 11 and includes a first loop 121 and a second loop 124. In addition, the first loop 121 and the second loop 124 are connected in parallel.
상기 제 1 루프(121)는 열감지부(122)와 제 1 고정저항(123)이 직렬로 연결된다.In the first loop 121, the heat sensing unit 122 and the first fixed resistor 123 are connected in series.
상기 열감지부(122)는 전열선(110)으로부터 확산되는 열에 대응하여 저항값이 변화되는 것으로, 상기 전열선(110)에 평행하도록 상기 나노유체(11)에 삽입된다. 또한, 상기 나노유체(11)의 내부에서 상기 전열선(110)으로 확산되는 열에 비례하여 저항값이 증가한다.The heat detection unit 122 has a resistance value corresponding to heat diffused from the heating wire 110, and is inserted into the nanofluid 11 so as to be parallel to the heating wire 110. In addition, the resistance value increases in proportion to the heat diffused into the heating wire 110 inside the nanofluid 11.
한편, 상기 열감지부(122)는 상기 전열선(110)에서 발생되는 열을 효과적으로 전달받기 위하여, 상기 전열선(110)과 일치하는 형상으로 형성될 수 있다. 또한, 열 전도성이 좋은 백금선 또는 텅스텐선 등으로 형성될 수 있다.On the other hand, the heat detection unit 122 may be formed in a shape corresponding to the heating wire 110, in order to receive the heat generated from the heating wire 110 effectively. Further, it may be formed of a platinum wire or tungsten wire having good thermal conductivity.
상기 제 2 루프(124)는 제 2 고정저항(125)과 가변저항(126)이 직렬로 연결된다.In the second loop 124, the second fixed resistor 125 and the variable resistor 126 are connected in series.
상기 가변저항(126)은 상기 열감지부(122)가 상기 나노유체(11)의 내부에 삽입될 때, 상기 나노유체(11)의 기본 온도에 따른 저항값에 대응하여 전압값이 변화된다. 또한, 상기 제 1 루프(121)의 열감지부(122) 및 상기 제 1 고정저항(123) 사이의 제 1 노드(121a)에 걸리는 전압과, 상기 제 2 루프(124)의 제 2 고정저항(125) 및 가변저항(126) 사이의 제 2 노드(124a)에 걸리는 전압을 동일하게 하여 증폭부(130)로 전류가 흐르지 못하게 한다.The variable resistor 126 has a voltage value corresponding to a resistance value according to a basic temperature of the nanofluid 11 when the heat sensing unit 122 is inserted into the nanofluid 11. In addition, the voltage across the first node 121a between the heat sensing unit 122 and the first fixed resistor 123 of the first loop 121 and the second fixed resistor of the second loop 124 ( The voltage applied to the second node 124a between the 125 and the variable resistor 126 is equalized to prevent current from flowing to the amplifier 130.
상기 제 1 노드(121a)에 걸리는 전압 및 상기 제 2 노드(124a)에 걸리는 전압은 상기 나노유체(11)의 온도가 변화되지 않으면 평형을 이룬다. 그러나, 상기 나노유체(11)의 온도가 상기 전열선(110)에 의해 변화되면, 상기 제 1 노드(121a)에 걸리는 전압 및 상기 제 2 노드(124a)에 걸리는 전압에 차이가 생겨 증폭부(130)로 전류가 흐른다.The voltage applied to the first node 121a and the voltage applied to the second node 124a are balanced if the temperature of the nanofluid 11 is not changed. However, when the temperature of the nanofluid 11 is changed by the heating wire 110, a difference occurs in the voltage applied to the first node 121a and the voltage applied to the second node 124a, and thus the amplification unit 130 Current flows through
즉, 상기 열감지부(122)가 상기 나노유체(11)의 내부온도에 비례하여 저항값이 증가되면, 상기 제 1 노드(121a)에 걸리는 전압이 증가하게 되고, 그 결과로 제 1 노드(121a)에 걸리는 전압 및 제 2 노드(124a)에 걸리는 전압의 차이가 증가하게 된다.That is, when the resistance of the heat detector 122 increases in proportion to the internal temperature of the nanofluid 11, the voltage applied to the first node 121a is increased, and as a result, the first node 121a is increased. ), And the difference between the voltage across the second node 124a and the voltage across the second node 124a increases.
증폭부(130)는 상기 브릿지 회로(120) 내부에서 생기는 전압차를 증폭하기 위한 것으로, 일측이 상기 브릿지 회로(120)에 연결되어 제 1 노드(121a) 및 제 2 노드(124a)에 걸리는 전압을 비반전단자와 반전단자로 전달받아 증폭하며, 타측이 별도의 표시부재, 즉, 데이터 기록계(12) 또는 오실로스코프 등에 연결되어 온도값을 출력한다.The amplifier 130 is for amplifying the voltage difference generated in the bridge circuit 120, one side is connected to the bridge circuit 120, the voltage applied to the first node 121a and the second node 124a It is amplified by receiving the non-inverting terminal and the inverting terminal, and the other side is connected to a separate display member, that is, a data recorder 12 or an oscilloscope and outputs a temperature value.
본 발명의 실시예에 따른 열확산율 측정장치(100)는 상기 브릿지 회로(120) 및 상기 증폭부(130)에 전원을 공급하는 제 2 전원공급부(140)를 더 포함할 수 있다.The thermal diffusivity measuring apparatus 100 according to the embodiment of the present invention may further include a second power supply unit 140 for supplying power to the bridge circuit 120 and the amplification unit 130.
또한, 상기 열확산율 측정장치(100)는 상기 나노유체(11)에 삽입되는 전열선(110)과 상기 열감지부(122)의 위치를 고정시키고 다른 장치들을 보호하기 위한 보호케이스(미도시)를 더 포함할 수 있다.In addition, the thermal diffusivity measuring apparatus 100 further includes a protective case (not shown) for fixing the position of the heating wire 110 and the heat sensing unit 122 inserted into the nanofluid 11 and protecting other devices. It may include.
상기 보호케이스는 중공형 직육면체 형상으로 형성될 수 있다.The protective case may be formed in a hollow rectangular parallelepiped shape.
상기 보호케이스는 상기 보호케이스의 중공부분에 상기 전열선(110) 및 상기 열감지부(122)가 노출됨으로써, 상기 전열선(110) 및 열감지부(122)의 위치를 고정시킬 수 있다. 또한, 상기 전열선(110) 및 열감지부(122)에 연결된 다른 장치부분들이 상기 보호케이스의 내부에 삽입되어 다른 장치부분들이 나노유체에 노출되는 것을 방지할 수 있다.The protective case may expose the heating wire 110 and the heat sensing unit 122 to a hollow portion of the protective case, thereby fixing the positions of the heating wire 110 and the heat sensing unit 122. In addition, other device parts connected to the heating wire 110 and the heat sensing unit 122 may be inserted into the protective case to prevent the other device parts from being exposed to the nanofluid.
이하에서는, 상술한 본 발명의 실시예에 따른 열확산율 측정장치(100)에 의해 얻어지는 측정값과 이론값을 비교하여 설명하기로 한다.Hereinafter, the measurement value obtained by the thermal diffusivity measuring apparatus 100 according to the embodiment of the present invention described above and the theoretical value will be described.
전열선(110)으로부터 거리 r만큼 떨어진 위치의 나노유체(11) 내부온도 상승은 하기 [수학식 1]과 같다.The increase in the internal temperature of the nanofluid 11 at a distance r from the heating wire 110 is expressed by Equation 1 below.
수학식 1
Figure PCTKR2010003768-appb-M000001
 Equation 1
Figure PCTKR2010003768-appb-M000001
여기서, α는 열확산율이고 k는 열전도율이고 q는 단위길이당 발생열량을 나타낸다. 상기 식에서 함수 E1을 수학 소프트웨어를 사용하여 산출하면 하기 [수학식 2]와 같다.Where α is the thermal diffusion rate, k is the thermal conductivity, and q is the amount of heat generated per unit length. In the above equation, the function E1 is calculated using mathematical software as shown in Equation 2 below.
수학식 2
Figure PCTKR2010003768-appb-M000002
 Equation 2
Figure PCTKR2010003768-appb-M000002
여기서 r은 상기 전열선(110) 및 열감지부(122) 사이의 간격으로, 대략 3mm이다. 엔진오일의 열확산율은 0.859*10-7이므로, 시간에 따른 변수 r2/4αt을 나타내면 하기 [수학식 3]과 같다.Where r is an interval between the heating wire 110 and the heat sensing unit 122, is approximately 3mm. Since the thermal diffusion rate of the engine oil is 0.859 * 10 −7 , the variable r 2 / 4αt with time is represented by Equation 3 below.
수학식 3
Figure PCTKR2010003768-appb-M000003
 Equation 3
Figure PCTKR2010003768-appb-M000003
이때, 15초 이후에는 상기 나노유체(11) 내부에서 부력에 의한 유동이 발생 되어 열확산율의 측정이 불가능하기 때문에, 본 발명의 실시예에 따른 열확산율 측정장치(100)를 사용하여 측정한 측정값은 대략 15초까지의 데이터만 사용된다.At this time, since the flow due to buoyancy is generated within the nanofluid 11 after 15 seconds, it is impossible to measure the thermal diffusivity, so the measurement measured using the thermal diffusivity measuring apparatus 100 according to the embodiment of the present invention. The value only uses data up to approximately 15 seconds.
상기 열감지부(122)는 상기 나노유체(11) 내부에서 대략 12.963Ω의 저항값을 가지며, 제 1 고정저항(123)은 2kΩ의 저항값을 가진다. 제 2 고정저항(125)은 10kΩ의 저항값을 가지며, 가변저항(126)은 1kΩ의 저항값 범위에서 조절된다.The heat sensing unit 122 has a resistance value of approximately 12.963Ω in the nanofluid 11, and the first fixed resistor 123 has a resistance value of 2kΩ. The second fixed resistor 125 has a resistance value of 10 kΩ, and the variable resistor 126 is adjusted in the resistance value range of 1 kΩ.
상기 전열선(110)에서 열이 발생 되기 전, 상기 브릿지 회로(120)가 균형을 이루는 상태의 가변저항(126)의 저항값은 64.815Ω이다. 상기 브릿지 회로(120)의 특징은 상기 제 1 고정저항(123)의 저항값이 상기 열감지부(122)의 저항값보다 매우 크다는 것이다. 온도상승에 따른 저항값의 변화는 하기 [수학식 4]와 같다.Before heat is generated in the heating wire 110, the resistance value of the variable resistor 126 in the balanced state of the bridge circuit 120 is 64.815Ω. A characteristic of the bridge circuit 120 is that the resistance value of the first fixed resistor 123 is much larger than the resistance value of the heat sensing unit 122. The change in the resistance value according to the temperature rise is shown in Equation 4 below.
수학식 4
Figure PCTKR2010003768-appb-M000004
 Equation 4
Figure PCTKR2010003768-appb-M000004
여기서 Rt는 상기 열감지부(122)의 저항값이고, Rt0는 상기 열감지부(122)의 본래 저항값이다. 이때, 온도상승이 크게 나타나는 엔진오일에서도 15초 동안 변화되는 온도는 1℃정도이다. 이와 같이 상기 나노유체(11) 내부온도의 1℃ 온도상승에 따라 변화되는, 상기 열감지부(122)의 저항값은 0.047Ω(=12.023*0.0039092*1)이다. 상기 열감지부(122)가 포함된 제 1 루프(121)의 총 저항값은 상기 나노유체(11)의 온도가 21℃인 경우 2012.963Ω(=2000Ω+12.963Ω)이고, 상기 나노유체(11)의 온도가 1℃ 상승되어 22℃인 경우 2013.01Ω(=2000Ω+13.963Ω+0.047Ω)이다. 따라서, 15V가 상기 브릿지 회로(120)에 인가되면, 상기 나노유체(11)의 온도가 21℃인 경우, 열감지부(122)가 포함된 제 1 루프(121)에 흐르는 전류는 7.4517mA이다. 또한, 상기 나노유체(11)의 온도가 1℃ 상승되어 22℃인 경우, 상기 열감지부(122)가 포함된 제 1 루프(121)에 흐르는 전류는 7.4515mA가 된다. 따라서 저항값의 크기가 작게 변화되는 경우, 상기 브릿지 회로(120)에는 거의 일정한 전류가 흐르게 된다. 따라서 상기 열감지부(122)의 저항값이 증가하면, 상기 제 1 노드(121)에 걸리는 전압이 증가되고, 그 결과로 제 1 루프(121) 및 제 2 루프(124) 사이의 전압차가 증가한다. 상기 제 1 루프(121) 및 제 2 루프(124) 사이의 전압차의 변화량과 온도의 변화량은 하기 [수학식 5]와 같다.Here, R t is the resistance value of the heat sensing unit 122, and R t0 is the original resistance value of the heat sensing unit 122. At this time, the temperature that changes for 15 seconds even in the engine oil that the temperature rise is large is about 1 ℃. As such, the resistance value of the heat sensing unit 122, which changes according to the temperature rise of 1 ° C. of the internal temperature of the nanofluid 11, is 0.047Ω (= 12.023 * 0.0039092 * 1). The total resistance of the first loop 121 including the heat sensing unit 122 is 2012.963Ω (= 2000Ω + 12.963Ω) when the temperature of the nanofluid 11 is 21 ° C., and the nanofluid 11 If the temperature of is increased by 1 ℃ 22 ℃ 2013.01Ω (= 2000Ω + 13.963Ω + 0.047Ω). Accordingly, when 15V is applied to the bridge circuit 120, when the temperature of the nanofluid 11 is 21 ° C., the current flowing in the first loop 121 including the heat sensing unit 122 is 7.4517 mA. In addition, when the temperature of the nanofluid 11 is increased by 1 ° C. and is 22 ° C., the current flowing in the first loop 121 including the heat sensing unit 122 becomes 7.4515 mA. Therefore, when the magnitude of the resistance value changes small, almost constant current flows through the bridge circuit 120. Therefore, when the resistance value of the heat sensing unit 122 increases, the voltage applied to the first node 121 increases, and as a result, the voltage difference between the first loop 121 and the second loop 124 increases. . The change amount of the voltage difference and the change amount of temperature between the first loop 121 and the second loop 124 are expressed by Equation 5 below.
수학식 5
Figure PCTKR2010003768-appb-M000005
 Equation 5
Figure PCTKR2010003768-appb-M000005
전압차의 변화량은 온도의 변화량에 비례하여 증가하므로, 상기 [수학식 3]을 상기 나노유체(11)의 질량, 열확산율, 그리고 전열선(110) 및 열감지부(122) 사이의 간격 등의 상수를 고려하면 하기 [수학식 6]과 같다.Since the amount of change in the voltage difference increases in proportion to the amount of change in temperature, Equation 3 is a constant such as the mass of the nanofluid 11, the thermal diffusion rate, and the interval between the heating wire 110 and the heat sensing unit 122. In consideration of Equation 6 below.
수학식 6
Figure PCTKR2010003768-appb-M000006
 Equation 6
Figure PCTKR2010003768-appb-M000006
상기 [수학식 6]을 변형하면, 하기 [수학식 7]과 같다.When the above Equation 6 is modified, the following Equation 7 is obtained.
수학식 7
Figure PCTKR2010003768-appb-M000007
 Equation 7
Figure PCTKR2010003768-appb-M000007
여기서 상기 [수학식 7]에 새로운 변수를 대입하면, 하기 [수학식 8]과 같다.Here, if a new variable is substituted into [Equation 7], it is as shown in [Equation 8].
수학식 8
Figure PCTKR2010003768-appb-M000008
 Equation 8
Figure PCTKR2010003768-appb-M000008
상기 [수학식 8]에 의해 상기 브릿지 회로(120)의 내부 전압차 상승 시간 데이터가 적절한 변환과정을 통하여, 일차 함수의 식으로 곡선맞춤 될 수 있다. 상기 [수학식 6]에서 C2 열확산율의 정보를 가지고 있고, 일차함수로 변형된 상기 [수학식 8]에서 A는 C2를 나타낸다. 측정된 실험데이터를 이용하여 계수 C2를 구하는 과정은, 먼저 전압신호에 로그를 취하고, 다음으로 시간의 역수를 구하고, 그 다음으로 구해진 시간의 역수에 음수를 붙인다. 그리고, 도 2에 나타낸 나노유체의 열확산율 측정장치(100)에 의해 구해진 전압변화데이터를 곡선맞춤을 통해 직선으로 표시하여 직선의 기울기를 구한다.By Equation 8, the internal voltage difference rise time data of the bridge circuit 120 may be curved by a linear function through an appropriate conversion process. And the C 2 with the information of thermal diffusivity in the [Equation 6], wherein the modification to a linear function in equation 8] A represents a C 2. In the process of obtaining the coefficient C 2 using the measured experimental data, first, the logarithm of the voltage signal is obtained, the reciprocal of the time is obtained, and then the reciprocal of the obtained time is negative. Then, the voltage change data obtained by the thermal diffusion rate measuring apparatus 100 of the nanofluid shown in FIG. 2 is displayed in a straight line through curve fitting to obtain the slope of the straight line.
엔진오일과 글리세린에 대한 전압변화데이터에 변환과정을 적용하여 최종적으로 열확산계수를 구하는 과정에서 C2는 하기 [수학식 9]와 같다.In the process of finally obtaining the thermal diffusion coefficient by applying the conversion process to the voltage change data for the engine oil and glycerin, C 2 is as shown in [Equation 9].
수학식 9
Figure PCTKR2010003768-appb-M000009
 Equation 9
Figure PCTKR2010003768-appb-M000009
따라서 열확산율 α는 하기 [수학식 10]과 같다.Therefore, the thermal diffusion rate α is as shown in Equation 10 below.
수학식 10
Figure PCTKR2010003768-appb-M000010
 Equation 10
Figure PCTKR2010003768-appb-M000010
r에 상기 전열선(110) 및 열감지부(122) 사이의 간격인 3mm가 대입되고, 도 3에 나타난 엔진오일 실험결과가, 곡선맞춤을 통해 직선으로 변화된 그래프의 직선의 기울기 33.26이 상기 [수학식 10]에 대입되어 열확산율이 계산되면, 하기 [수학식 11]과 같다.3mm, which is the interval between the heating wire 110 and the heat sensing unit 122, is substituted in r, and the engine oil test result shown in FIG. 3 is a slope of the straight line 33.26 of the graph changed into a straight line through curve fitting. 10] and the thermal diffusivity is calculated, as shown in [Equation 11].
수학식 11
Figure PCTKR2010003768-appb-M000011
 Equation 11
Figure PCTKR2010003768-appb-M000011
엔진오일의 열확산율인 0.859*10-7과 실험을 통해 측정된 측정값을 비교하면 0.6%(=(0.854-0.859)*100/0.859)의 오차가 있음을 알 수 있다.Comparing the measured thermal diffusivity of the engine oil 0.859 * 10 -7 with the experimental results, it can be seen that there is an error of 0.6% (= (0.854-0.859) * 100 / 0.859).
도 4에 나타난 글리세린 실험결과가, 곡선맞춤을 통해 직선으로 변화된 그래프의 직선의 기울기 30.862가 상기 [수학식 10]에 대입되어 열확산율이 계산되면 하기 [수학식 12]와 같다.When the result of the glycerin experiment shown in FIG. 4 is substituted for the straight line 30.862 of the graph changed into a straight line through curve fitting in Equation 10, the thermal diffusion rate is calculated as in Equation 12 below.
수학식 12
Figure PCTKR2010003768-appb-M000012
 Equation 12
Figure PCTKR2010003768-appb-M000012
글리세린의 열확산율인 0.935*10-7과 실험을 통해 측정된 측정값을 비교하면 1.6%(=(0.920-0.935)*100/0.935)의 오차가 있음을 알 수 있다. 즉, 상기 나노유체(11)의 이론에 따른 열확산율과 실험을 통해 측정된 열확산율간에는 오차가 거의 없다.Comparing the heat diffusion rate of glycerin 0.935 * 10 -7 and the measured value measured through the experiment, it can be seen that there is an error of 1.6% (= (0.920-0.935) * 100 / 0.935). That is, there is almost no error between the thermal diffusivity according to the theory of the nanofluid 11 and the thermal diffusivity measured through experiments.
이상, 본 발명의 실시예에 따른 나노유체의 열확산율 측정장치에 대하여 설명하였지만, 본 발명의 사상을 벗어나지 않는 범위 내에서 수정, 변경 및 다양한 변형실시예가 가능함은 당업자에게 명백하다.As described above, the apparatus for measuring the thermal diffusivity of the nanofluid according to the embodiment of the present invention has been described, but it is apparent to those skilled in the art that modifications, changes, and various modifications can be made without departing from the spirit of the present invention.

Claims (5)

  1. 전원을 공급받아 나노유체의 내부에 삽입되어 열을 가하는 전열선;A heating wire that receives power and is inserted into the nanofluid to apply heat;
    상기 전열선으로부터 일부분이 소정간격 이격되도록 배치되고, 상기 전열선으로부터 확산되는 열에 대응하여 변화되는 저항값에 근거하여 내부에 전압차가 발생되는 브릿지 회로; 및A bridge circuit in which a portion of the heating wire is spaced apart from the heating wire, and a voltage difference is generated therein based on a resistance value changed in response to the heat diffused from the heating wire; And
    상기 브릿지 회로의 상기 전압차를 전달받아 상기 전압차를 증폭하여 출력하는 증폭부;를 포함하는 것을 특징으로 하는 나노유체의 열확산율 측정장치.And amplifying unit receiving the voltage difference of the bridge circuit and amplifying the voltage difference to output the amplified voltage difference.
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 브릿지 회로는 상기 전열선으로부터 확산되는 열에 대응하여 저항값이 변화되는 열감지부;The bridge circuit may include: a heat sensing unit having a resistance value changed in response to heat diffused from the heating wire;
    제 1 고정저항이 직렬로 연결되어 있는 제 1 루프; 및 A first loop having a first fixed resistor connected in series; And
    제 2 고정저항과 가변저항이 직렬로 연결된 제 2 루프를 포함하고, A second loop in which the second fixed resistor and the variable resistor are connected in series;
    상기 제 1 루프 및 제 2 루프는 병렬로 연결된 것을 특징으로 하는 나노유체의 열확산율 측정장치.And the first loop and the second loop are connected in parallel to each other.
  3. 청구항 2에 있어서,The method according to claim 2,
    상기 열감지부는 상기 전열선에 대응되도록, 상기 나노유체의 내부에 삽입되는 것을 특징으로 하는 나노유체의 열확산율 측정장치.The heat detection unit is a thermal diffusion rate measuring device of the nanofluid, characterized in that inserted into the interior of the nanofluid so as to correspond to the heating wire.
  4. 청구항 2에 있어서,The method according to claim 2,
    상기 열감지부는 상기 전열선으로부터 확산되는 열에 비례하여 저항값이 증가되는 것을 특징으로 하는 나노유체의 열확산율 측정장치.The heat detection unit is a thermal diffusion rate measuring device of the nanofluid, characterized in that the resistance value is increased in proportion to the heat diffused from the heating wire.
  5. 청구항 4에 있어서,The method according to claim 4,
    상기 제 1 루프 및 제 2 루프 사이의 상기 전압차는,The voltage difference between the first loop and the second loop is,
    상기 열감지부의 저항값에 비례하여 증가되는 것을 특징으로 하는 나노유체의 열확산율 측정장치.The apparatus for measuring the thermal diffusion rate of nanofluid, characterized in that the increase in proportion to the resistance value of the heat detection unit.
PCT/KR2010/003768 2009-12-02 2010-06-11 Apparatus for measuring thermal diffusivity in a nanofluid WO2011068293A1 (en)

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