# Heat transfer unit dimensions in (N * mm)?

I used units as per ccx Table 1: Frequently used units in different unit systems. mm, N, s, K and I get stupefied with achieved heat transfer unit dimensions.

Body is a cube.

Excerpt from ccx manual “Now, since force = mass × length / time2 , we get that mass = force × time2/length. This leads to Ns2 /mm for the mass and Ns2 /mm4 for density.”

Or my formulas are not for use with the unit system mm, N, s, K, aren’t they?

My advice would be to stick to SI units [m,kg,s,K].

Then density is kg/m3, thermal conductivity is W/(mK) and specific heat is J/(kgK).

It will make your calculations less error-prone if you don’t have to do all kinds of conversions.

I gave it a deep thought but I did not find how to do geometry in meters or centimeters. cgx / ccx are unit less though.

Just specifiy distances and lengths in meters.
For example in the preprocessor file for `cgx`, you can do simple calculations when you define values, e.g. to convert [mm] to [m]:

``````# Body sides
valu a1 / 10 1000
valu a2 / 10 1000
# Body depth
valu d / 3 1000
# Temperature
valu Ti + 25 273.15
``````

Strange thing I did not think of conversion at all, I thought of something else. What it is that else, no idea.