None because the thermostat itself doesn't supply any cooling
the k is going to be a factor of water (or coolant) and the material used
If your trying to calculate the thermal efficiency requirements for a cooling system you would be better off converting the engines power to btus and calculating the cooling capacity based on that
the cooling requirements are going to be directly proportinate to the airmass of the engine
its simply a compressor and can be calculated as such
I was actualy referring the k value as a flow restriction value, ex. 90 pipe has k balue of 1.5, 45 has 1.2.
Basicaly what im trying to do is simulate the flow restiction a thermostat poses fully open with an oriface.
oops my mistake, i tend to over think everything im analytical like that at times
i couldn't even begin to help you, almost seems like it would be specific to a particular thermostat
some thermostats have different designs and flow capabilities, there are many different diameter thermostats as well, some have a single bypass some have 3 some have none
then the housing itself on some engines are a 90* such as my ls1 camaro, where as some are mounted in the intake manifold inside a 45* elbow while others are mounted with a 90* and everything in between