First issue: 24/12/2014
This article reports the verification activities and the calorimetry measurement performed on the pump used by Tadahiko Mizuno during his recent measurement of the alleged anomalous heat due to LENR, which was discussed in our previous published analysis; according to our opinion and measurements the origin of the so-called anomalous heat, claimed by Mizuno and Jed Rothwell as due to a LENR phenomenon, is instead simply due to clear errors in measurement and evaluation of the involved parameters.
In his report Rothwell says that the power dissipated by the pump was less than 0.5W, probably 0.25W, but certainly less than 1W.
In order to demonstrate which are the real and actual values, we got exactly the same model of pump used by Mizumo and Rothwell:
We performed a calorimetry measurement in order to evaluate the actual heat released by the pump. We used exactly the same adiabatic calorimetry method (the one originally used on the cell by Mizuno and Rothwell) confirming that this type of Calorimetry, if well done, allows precise and reliable measurements to be obtained.
Our calorimetry measurement showed that the pump dissipates 4.3W into the water, in line with what expected from our previous analysis of the theoretical data in the report by Rothwell.
It is then confirmed that in the Mizuno reactor, originally presented at the ICCF-18 conference, and measured via different calorimetry methods during 2013 and 2014 with the collaboration of Jed Rothwell, the excess heat claimed and attributed to LENR is instead due to the water pump dissipation in association with strong fluctuations in ambient temperature between day and night.
Measurement method description
The method used to measure the heat transferred from the pump to the water is extremely simple and did not require more than an afternoon of work. The same method had been previously suggested to Rothwell who refused to ask Mizuno to run it.
In Figure 3 one can see the simple set-up:
The pump makes water pass through a Dewar vessel by means of an external hydraulic circuit. The total amount of water was 800g and the heat capacity of the container was neglected. Although not essential, to increase the accuracy we used as external pipe a silicon tube with a 5mm inner diameter, and 40cm long in order to make the pump operate on the same working point in the PQ diagram.
In fact, as we know, for a given flow rate the pressure drop in a pipe depends, as a first approximation, on the inverse of the diameter raised to the 5th power. Since the Mizuno cell used a 16 meters long pipe with a 10mm inner diameter, we could obtain the same pressure drop by using about 0.5m of 5mm pipe. In the actual test, due to height problems the length was reduced to 0.4m.
Since the pump, built for the Japanese market, required a 100V 50Hz power feeding, we used a Variac, monitoring its output by means of a voltage tester. A preliminary simple test was performed to check if the Dewar vessel heat loss was really negligible. So we put inside 800g water at about 30 ° C, waiting about one hour to have the temperature stabilized; then the water temperature decrease was recorded during a 45 minute period.
The details are as follows:
- Initial temperature: 28.0 ° C
- Final temperature: 27.1 ° C
- Room temperature: 21.0 ° C
These data provide a heat exchange coefficient K: = 0.15W/°C that is more than acceptable for the test, as long as operation is kept at temperatures not very far from the room temperature.
Before the test, the pump was preheated for about an hour in order to evaluate the water flow (see Figure 4).
Then a simple set-up was prepared with continuous reading of water and ambient air temperatures by two different thermometers.
The hydraulic circuit was then loaded with 800g of water at 14 ° C, and the pump was started [it is not self-priming] (see Figure 5).
We had to wait about an hour to have the water temperature close to room temperature; then data were collected through successive photographs. Figure 6 and Figure 7 show the values used in the final calculation.
At the end of the test the two thermometers showed the same values (see Figure 8).
At the end of the test the two thermometers showed the same values (see FiguThe pump motor temperature was measured as well; it was found to be 45 ° C (see Figure 9).
Figure 10 shows the time evolution of measured temperatures.
The power P transferred from the pump is given by:
P = 4183 x 0.800 x (T2–T1) /t
- 4183 is the specific heat of water @ 20°C [J/kg°C]
- 0.800 the mass of water to be heated [kg]
- T2 is the final temperature [°C]
- T1 is the initial temperature [C°]
- t is the time interval between the two measurements [s]
Considering the values obtained from the two photographs (Figure 6 and Figure 7) taken at 0.5 ° C below (T1) and 1.0 ° C above (T2) the ambient temperature and taken respectively at 15:51:45 pm and 16:12:24, [that is at an interval of 20 minutes and 39 seconds], one can calculate that the power transferred from the pump to the water is equal to 4.3W, i.e. 0.4W higher than what we estimated theoretically in our previous Post. The difference is due to the conservative choices adopted there.
Calorimetry measurement performed on the same pump model used by Tadahiko Mizuno has confirmed that the pump dissipation is an order of magnitude higher than that assumed by Jed Rothwell: as such it can explain exactly the apparent excess heat measured.