Key features

• 고정밀 연구 장비
• 넓은 열전도도 측정 범위(10~2000mW/mK)
• 온도의 함수로써 열전도도 측정
• Hot Wire 기법을 따른  instationary resistance 측정
• ASTM D7896-19에 일치
• 견고한 스테인리스 스틸 센서 사용
• 넓은 온도 범위(-50°C~300°C)
• Convection의 영향 없이 빠르고 정확하게 측정
• 모든 유체와 분말 또는 젤에 적용가능
• 소량의 샘플 사용(40ml)
• 뛰어난 재현성(±1%)
• 짧은 설정 시간
• 빠르고 쉬운 작동법
• PC 소프트웨어에 의한 자동 온도 조절 및 열전도도의 측정 
• 뛰어난 기능의 LAMBDA 소프트웨어 포함
• 자동으로 샘플의 온도를 조절하기 위한 thermostat 옵션 가능

 

Easy and fast measurement

LAMBDA를 사용한 열전도도를 측정 시 40ml의 소량 샘플이면 충분합니다. Hot wire 열선이 있는 센서를 샘플에 담그면 LAMBDA는 1분 간격으로 유체의 온도와 열전도도를 측정합니다.

 

Fields of application

컴팩트하고 매우 정확한 본 기기는 실험실과 현장 모두에서 유연하게 적용하는 새로운 가능성을 열어줍니다:

• Optimization of fluid development: HTF, 실리콘 오일, 절연유 등의 개발을 개선할 수 있습니다.
• Optimization of fluid applications: 열 물성 관련 문제를 해결하거나 공정 중에 열 전달 특성을 최적화할 수 있습니다.
• Quality control: 입고되거나 출하하는 유체의 열전도도를 확인할 수 있습니다.
• Fluid analysis in the field: 서비스 및 유지 보수 기간을 최적화할 수 있습니다.

 

Modes of operation

Thanks to its intuitive menu the LAMBDA meter can be operated in stand-alone mode. In addition you may use your PC with our powerful LAMBDA software to set up automatic conductivity measurements within a temperature range of your choice. The captured CSV-based data can be exported easily, e.g. to EXCEL, for your further analysis.

 

 

Optional thermostat for automatic sample temperature control

열전도도측정기 모델 LAMBDA에 의해 자동으로 제어될 수 있는 다양한 적합한 온도 조절 장치((thermostats)를 제공하므로 필요한 모든 샘플 온도를 신속하게 설정할 수 있어, 온도에 따른 열전도도측정이 가능합니다.

• Dry-block thermostat (standard, as shown below): RT to 300°C
• Julabo fluid thermostat with heat exchanger vessel for additional cooling: -25°C (or below) to 300°C

 

Technical data

Suitable media	fluids, gels, powders
Sample quantity	approx. 40 ml
Test standard	conforms to ASTM D7896-19 based on ASTM D2717
Measuring range	10 to 2,000 mW/(m*K)
Repeatability limit	1 %
Temperature range - sensor	-50°C to 300°C
Temperature accuracy	± 0.1 K
Temperature measurement	PT100
Pressure range - sensor	0 to 35 bar (optional HP version up to 500 bar available)
Measuring time	approx. 60 s
Connectivity	RS-232 interface (adaptable to USB)
Display	LCD (4 x 16 digits)
Dimensions electronic unit (LxWxH)	370 x 235 x 150 mm
Weight - system	approx. 2.9 kg
Power supply	110 - 240 V AC, 50/60Hz
Energy consumption	15W
Outer dimensions sample vessel (screw-on cup)	D = 38 mm (equals inner diameter of thermostat jacket); L = 110 mm (equals immersion depth into thermostat)
Optional accessories	Dry-block thermostat for automatic testing above RT Fluid circulator w/ extra vessel for testing below RT

 

---

What is Thermal conductivity

---

The thermal conductivity lambda (λ) of a solid, a fluid or a gas may basically be understood as the speed at which a defined amount of heat travels as it goes through a particular substance. A low λ value means low thermal conductivity.

For both liquids and gases lambda highly depends on the temperature, whereas pressure dependence is comparitively low. The measure for lambda is W/(m*K) (Watts per Meter and Kelvin).

Typical lambda values for different fluids

Fluid	Thermal conductivity λ (W/(m*K))
gasoline	0,140
glycerin	0,286
machine oil	0,126
ethanol	0,185
water @ 10°C	0,580
water @  60°C	0,644

 

Lambda measurement for fluids, pastes and gels (flucon LAMBDA)

flucon's Measuring system LAMBDA allows you to determine the temperature-dependent thermal conductivity of liquids, pastes or gels with ease. With its hot-wire technology the LAMBDA is both precise and comfortable to handle. Its measuring range from 0,01 to 2 W/(m*K) and its temperature range -50°C to 150°C (HT version for even higher temperatures available) make it the perfect tool for your thermal fluid analysis.

 

Workflow for the determination of the thermal conductivity (flucon fluid analysis)

flucon not only offers their portable LAMBDA measuring system but also in-house fluid analysis in our own high pressure laboratory. Customers may send in small samples (300 ml) of the fluid they would like to have tested and then the following steps will be performed:

• Laboratory measurement of the thermal conductivity as a function of temperature and pressure using a transient measuring method preventing an influence of convective flow of heat on the measuring result
• Mathematical description of the pressure/temperature-dependant thermal conductivity
• Graphical data preparation

Fundamentals of measuring λ

Stationary vs. instationary method

There are two ways of measuring thermal conductivity: the stationary and the instationary method. The stationary method is principally simpler as it proceeds from a constant temperature level, whereas the instationary method takes the problem of a changing temperature field into account. There is an advantage resulting from this extra effort however: the instationary method provides measuring results for the thermal conductivity much faster and the results are less influenced by convection.

The effects of convection for the stationary method

According to POLTZ the stationary method is seriously hampered by the fact of thermal conductivity induced by convection. In Tuluol, for example, an average flow rate of only o.01 mm/min leads to a deviance of about 1% in the data obtained for the thermal conductivity due to free convection. Therefore, POLTZ concludes that the stationary method, especially in an experimental set-up where the thick layers are concerned, cannot provide measuring data without a noticeable influence of convection. Furthermore, great care must be taken to avoid any kind of forced convection, such as would be caused by vibration of the measuring apparatus.

Measuring lambda. With LAMBDA.

The LAMBDA Thermal Conductivity Meter developed by flucon will give you the advantages of the fast instationary transient hot-wire method while at the same time excluding the influence of convection in the measuring process. This is achieved by computational processing of the data obtained within very short periods of time (approx. 800 ms) which in turn leads to a very short over-all duration of the test process (approx. 60 s).

The hot-wire of the LAMBDA serves as the source of heat and as the transducer at the same time. In order to raise the temperature, the hot-wire is subjected to a constant measuring current; as the surrounding medium warms up, the resistance of the hot-wire will change in accordance with the thermal viscosity of the surrounding medium. Thus the change of voltage in the hot-wire indicates the change of temperature taking place in the surrounding medium.