by Guest » Fri Jun 25, 2004 9:34 pm
Given that both your units are raised to the power of -1, this is the same as inverting both (i.e. reciprocal).
This would make the metric one W/mÂ²Â°K. This has Watts (unit of power or rate of energy flow) on the top, whereas the imperial one would have Btu/hr (also rate of energy flow) on the bottom. So I think you have one too many ^-1 in there.
These look like units connected to thermal conductivity to me so I would assume that what you are probably after is Btu/hr.ftÂ².Â°F to [mÂ².Â°K/W]^-1. If the ^-1 is truly applied to the imperial unit rather than the metric then divide by the factor below rather than multiply.
As mentioned above [mÂ².Â°K/W]^-1 is the same as W/mÂ²Â°K, so to convert Btu/hr to Watts multiply by 0.2931. Because the ftÂ², mÂ², Â°F and Â°K are at the bottom you divide by 0.3048Â² and 0.5556 respectively. Putting this lot together gives you:
0.2931/(0.3048Â² x 0.5556) = 5.6784