The radiator is instrumented with thermocouples on the inlet and outlet coolant streams and a flowmeter for calorimetry (measuring heat rejection). A squirrel-cage fan above provides the cooling air through the stainless steel sheetmetal ductwork.

Here is my setup for calibrating the coolant flowmeter. Water recirculated between the blue drum on the right to the red pump (which had to be primed using the copper tubing). The water then flowed through the radiator to the flowmeter in order to simulate actual operating conditions. I took readings at a given setting, and then moved the ladder until the water exit tube was over the blue dump tank on the left, which was calibrated for a certain amount of volume. Using a stop watch, I was able to calculate the volumetric flow rate. Not shown is a submersible pump used to transfer the water from the dump tank back to the recirculating drum.