Here's a crudely drawn representation of my heat die concept. A cartridge heater (shown as red, such as the ones pH has - Watlow Electric?) is imbedded in a chunk of copper. Heat flows up the riser towards the water block. Two thermocouples are embedded into the riser at, say 10 mm intervals.
At steady state the temperature gradient up the riser will be linear and proportionate to the heat flow. Since we know the cross sectional area of the riser and the distance between the thermocouples, we can calculate the heat flow from the temperature difference. Additionally, we can infer the temperature of the die surface without having a probe directly on the die, avoiding the problems of a 'heat shadow'.
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