I believe that KD2 Pro is a kind of a needle probe using the line source method. Any probes that use the line source method need to generate heat.  So, when you apply your probe to measure thermal conductivity of liquid, you have to minimize the amount of heat to avoid thermal convection in liquid.  Because the line source method works only for conduction, thermal convection is an error source.  A half-space device (modified from a needle probe) has less thermal convection than a needle probe. Probably the half-space device is better choice if you can use it.  

Dear Vipin,

it is a very popular technique. In my last paper (attached), you can find some examples of the use of the device for measure the thermal conductivity of nanofluids (refs. [7,8,21–25]).

Regards,

Gaweł

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I believe that KD2 Pro is a kind of a needle probe using the line source method. Any probes that use the line source method need to generate heat.  So, when you apply your probe to measure thermal conductivity of liquid, you have to minimize the amount of heat to avoid thermal convection in liquid.  Because the line source method works only for conduction, thermal convection is an error source.  A half-space device (modified from a needle probe) has less thermal convection than a needle probe. Probably the half-space device is better choice if you can use it.  

Thank you Prof. Zawel for your response and for sharing your work here.I will read it and write back to you.

Thank you

 Thank you Prof. Lee.

i would like to know whether there was any significant difference in thermal conductivity values measured by KD2 pro and the half-space device.

And the fact that the KD2 works on transient technique;the measurement will last only for few seconds so natural convection errors can be disregarded or are negligible..isnt it?

Thank you for your response

Please try to measure thermal conductivity of water using the KD2. At room temperature, thermal conductivity of water should be ~0.6 W/mK. If KD2 provides about 0.6 W/mK for water, then it would be fine. But if you have different thermal conductivity value for water, then it would be due to thermal convection. In my experience, short time is enough to create thermal convection. And liquid should be very stable and calm without any small movement during your measurement.  For half-space device, please visit the website of "TeKa" company from Germany. 

I am using KD2 pro as well. And I totally agree with Youngmin Lee. You need to pay a huge attention to do good enough measurement, it is time consuming to achieve a reliable result. Unfortunately the convection is another problem which you probably will meet and will be a significant obstacle to deal with. Anyway, with a bit of experience you are able to obtain proper data in a short time.

As Youngmin Lee mentioned, if you tried measuring thermal conductivity of water, you would be suprise how difficult it may be (mainly due to the convection). But it originates from the viscosity, there are many papers about the dependence of thermal conductivity with viscosity.

Thank you Prof. Youngmin and Thank you Kamil for your reply.

where can i buy KD2 pro and which company