David Roberson <[email protected]> wrote:
> Finally, the leakage power entering the water from the pump has to be > determined since it has a significant effect upon the total calculation. > Even though it is on continuously, it is impossible to achieve an accurate > calculation without its influence being considered. > The power has to be measured, but it does not have to be measured with precision. As long as you show that it remains the same at all times, then you can be sure this heat is included in the baseline and it cannot affect the adiabatic calorimetry. The calibrations show that the pump heat is stable, but it is difficult to measure exactly how much heat this is. The pump heat is low, and it can only be measured when everything else in the system is turned off. This means total heat is close to zero and the noise from ambient temperature changes drown the signal. Calorimetry always works better power level above zero. When a calorimeter measures from 0 to 10 W, it can detect the difference between 1.0 and 1.1 W with greater confidence than between 0.0 and 0.1 W. The pump is described here: http://www.iwakipumps.com.vn/doc_viewer.aspx?fileName=/upload/file/md.pdf There are two sources of heat from the pump, and they are both likely to stable: 1. Work by the pump itself, by the impeller. The pump consumes 10.8 W of electricity. The other pumps in the MD series are 15% efficient, so the pump cannot deliver more than 1.5 W of mechanical energy. It probably delivers much less than this. In any case, power consumption is steady so mechanical power will also be steady. 2. Heat from the motor. There is no direct, physical connection between the motor and the pump. As shown in the figure on p. 4, the motor turns a magnet, which turns another magnet inside a waterproof section at the end of the pump. The second magnet turns the impeller. This is done to make pump waterproof and gas tight. This also minimizes the heat conducted from the pump motor to the impeller. Very little heat will be conducted by this path because plastic is a poor conductor; and because the motor is designed to be self cooling; the pump housing is cool to the touch; and Mizuno has a small fan blowing on the pump at all times. The conductivity of the plastic shell cannot change, so however much heat it conducts, as long as the motor consumes the same amount of power the level of conducted heat must be the same. Therefore it cannot affect the adiabatic calorimetery. > It was then possible to subtract this curve from the measured coolant > temperature response to have a clear view of the true signal that is > generated by the power pulse entering the system and any excess power it > originates. I added a three pole digital filter following the subtraction > to eliminate most of the nasty noise remaining. > This is complicated because you do not know how much anomalous heat there is in the first place. That is what you are trying to derive. We need calibrations without any reactive Pd metal in the reactor, and no anomalous heat, so that we know exactly how much energy is input and output. I hope we will soon have these. This simplifies the problem greatly. It will also tell us exactly how much heat is captured by the reactor stainless steel. > Each of the three input power pulses contained within this particular data > file (October 21, 2014 ) was easy to measure when subjected to my > process. I could determine that about 25% extra energy was generated by > the Mizuno device for each pulse. > I got 38%, based on a simpler method. (See Table 1.) I ignore heat from the pump for the reasons explained above. If you are including a small contribution from the pump that might explain the difference between 25% and 38%. And, if you are including that heat, I am confident you are making a mistake. > That is about 2500 joules for each one of the three. An explanation as > to why this number is less than that reported is revealed by my latest > technique of separating out the individual contributions. > Did you also take into account heat captured by the reactor metal? My 38% is only for the water. > The fact that the pump is on all of the time does in fact tend to hide its > contributions to the final coolant measurements as has been assumed. > No, it does not "hide" the contributions. It negates them. The contributions are already there at the start, and they cannot increase in the "final coolant measurements." (The plastic cannot suddenly conduct more heat; the impeller cannot do more work.) The heat from the pump is in exactly the same category as the heat from the overhead lights. It is part of the unchanging baseline. The heat from the HVAC would also be part of that unchanging baseline if Mizuno would improve the HVAC and leave the heater turned on day and night. I think he is doing this now, at my request. As I noted in the report I hope he can upgrade the quality of the HVAC equipment. The fact that the pump impeller heat is generated on the *inside* of the calorimeter, whereas HVAC heat and pump motor heat comes from the *outside*, has no bearing on the situation. The location where the heat originates is not the issue. You cannot negate the HVAC contribution the way you negate the pump because the HVAC varies so much and it turns off for hours! If the pump were turned off for hours you could not negate it either. Or if the pump suddenly doubled its output, you couldn't negate it. As I said, this only applies to adiabatic calorimetry. Pump heat would definitely be a problem with any other method of calorimetry. > The biggest problem is that during the night time hours when the ambient > drops heat is extracted from the system through the thermal resistance as > the device cools. > Yes. I hope this problem will soon be corrected. > In the early morning hours the heating system begins to operate and the > ambient rises several degrees C <#14b3b6587f88ed2f_14b38b47fa9816a6_> at > a rapid rate. If you recall the step response portion of my model above > you will understand why this is so important. The final temperature that > the average ambient step wants to drive the coolant toward becomes greater > than the coolants initial value. The coolant is not able to keep up with > the rapidly rising morning ambient due to the time constant so it lags > behind. > Exactly. This is too complicated to model properly, I think, although you seem to be doing a brave attempt. I hope that Mizuno eliminates these fluctuations, so that we do not have to account for them. > The good news is that the calorimeter can be used as is with my > calibration system obtaining an accuracy of approximately 1000 joules per > pulse. > The better news is that with proper environmental controls we will be able to use a simpler calibration model. That's an example of fixing the problem with hardware rather than software. - Jed
