condenser capacitor / capacity measurment working principle

[themroc]

I am working for a company which manufactures turbulators to improve the efficency in tubular heat exchangers.
A sketch of those Inserts can be found here:

http://www.calgavin.com/hitran/hitran.htm

Those turbulators induce turbulence near at the tube wall and therefore improve the heat transfer. The packing density and wire thickness of those turbulators can be altered.
They are manufactured from Stainless Steel

Now my Question:
As more Metal touches the wall as better the performance.
I am looking for a simple device which could give me an indication how much metal contacts the wall on an electronic basis, That means if I put an higher packed Insert into the tube it should give me an different reading compared to a lower packed Insert.
maybe someone can comment on the following:

1. First I tried to measure how much metal is in contact with the tube wall by using a simple Voltmeter and measured the electrical resistance between tube wall and Insert core wire. Unfortunately the resistance was so small that in essens I could not measure anything sensible. Would this in principle work?

2. I thought about a second principle but did not do this yet maybe someone could advise:
If I use a metal tube which is coated with paint then with the Insert inside it should work as an capacitor/condenser.
I should get more capacity if there is more metal in near contact to the wall. Is this right??
The tubes are typical 1'' or 3/4 inch in diameter. Where can I find measurment devices to meassure the capacity?

Any comment is wellcome!!

 

[ScottyUK]

You might want to test the principle using the capacitance range of a multimeter. Most of the mid-range hand held meters have a capacitance function these days.


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If we learn from our mistakes I'm getting a great education!

 

[itsmoked]

There are milli-ohm meters for measuring thousanths of an Ohm.

Other possibilities would be friction - how hard to displace the turbulator some tiny distance. Use say a spring compression scale.

Banging the pipe. The pipe would have a different resonance the more it's surface is coupled to another structure, (the turbulator).

I'm a firm believer in direct measurement of the desired result. I'd try measuring the actual heat transfer instead. It could be at some point of "packing" you actually reverse the desired result. There would be many ways of achieving this.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[themroc]

Thanks for the answers.
In principle I agree with itsmoked. A direct meassurement is defenitely better. But in this case a direct meassurement takes very long and if the resistance meassurments gives an indication than we could use this for screening purposes.
Do you think it would work to meassure the resistance, taking into account that some metall will be in direct contact with the wall?