Several people have asked me whether Mizuno checked for measurable heat from the circulation pump. The answer is yes, he did. As I wrote in the report there was no heat and: "this was confirmed by running the pump for a day with all other systems turned off." There was no measurable heat from water friction or from the pump motor. Perhaps I should revise the report to state that more clearly.
This was done with previous configuration, but that was perfectly adequate to measure heat from a single source such as the pump. There was no measurable heat then and there is none now. You can confirm this yourself. Get a 16 m length of 1 cm internal diameter plastic hose and run water through it at 8 L from the sink. You will see that friction from the water does not produce any sensible heat or any measurable temperature rise. I suggest a simple method would be to tape a thermocouple to the tube, turn on the water, turn it off for a while, and turn it on again. Use the min-max feature to record the temperature range in each phase. You will not see any difference. Of course there is some heat, but it cannot be measured with these instruments. The temperature rise is far less than 0.1 deg C. Remember that this hose is wrapped around a 50.5 kg metal heat sink, so even if did get slightly warm, so will the metal. The total thermal mass is equivalent to ~9 kg of water. Note also that the mechanical power of human heart is 1.3 W, and it pushes the blood at 5 L/min against far greater resistance than a 1 cm plastic tube. As stated in the paper, this is an Iwaki Co. Magnet Pump MD-6K-N. The specifications are here, on p. 5: http://www.iwakipumps.com.vn/doc_viewer.aspx?fileName=/upload/file/md.pdf Input power is 18 W, output 3 W. I am sure that is 3 W at maximum flow rate against more resistance than this. Furthermore, if the pump were the source of heat, the reactor would not cool down. You can see that it does cool down. The data clearly shows that it returns to room temperature. The pump is run at all times when there is data collection. You can also confirm this by downloading the spreadsheets and compare Oct 21 (when the pump was off) and Oct 22. The Oct. 21 data is shown in Fig. 14. You can see that the cooling rate is the same on both days when you combine the reactor and Dewar on Oct. 21. Bear in mind there are two separate thermal masses on Oct. 21: the Dewar with 3 kg of water, and the reactor with 50.5 kg of stainless steel and ~1 kg of water. - Jed
