The calibrations you show seem to be for reactor temperatures that are substantially lower than those where Mizuno and Rothwell claim to detect excess heat production. What temperature ranges are you using for your fueled runs? .
I don’t see any reactor temperatures posted, just air temperatures.
I don’t see any reactor temperatures posted, just air temperatures.
Absolutely right. My mistake.
What is the typical air volume rate going through the calorimeter?
Total air volume is in the 450 SLPM range for a blower voltage of 12.5V. I don't try and control blower power, but I assume it is fairly constant.
The calibrations you show seem to be for reactor temperatures that are substantially lower than those where Mizuno and Rothwell claim to detect excess heat production. What temperature ranges are you using for your fueled runs? .
Bruce__H, Here are the reactor heater internal temperature and the reactor external temperatures. The reactor external temperatures are displayed as the blue and green lines. The blue line pretty much overlays the green. The "gas end" thermocouple is located on the end of the reactor closest to the 1/2" vacuum/gas connection. The "heater end" thermocouple is located on the end of the reactor closest to the heater connection.
Total air volume is in the 450 SLPM range for a blower voltage of 12.5V. I don't try and control blower power, but I assume it is fairly constant.
Thanks. I was running some calculations and that is pretty close to what I came up with. (472.8 SLPM at 100% recovery, estimating the outlet air temperatures). That means that the overall airflow is about 2/3 of what Mizuno was running through his. (I realize it is not a replication of his calorimeter.)
I woke up two nights ago wondering if somehow the Mizuno blower fan was being run at 10.45 V for calibration but only 8.5 to 9 V for the excess heat runs due to inserting the 3 ohm sense resistor only in excess runs. Of course that might be possible once, but is very unlikely for many different runs to keep doing that.
I woke up two nights ago wondering if somehow the Mizuno blower fan was being run at 10.45 V for calibration but only 8.5 to 9 V for the excess heat runs due to inserting the 3 ohm sense resistor only in excess runs. Of course that might be possible once, but is very unlikely for many different runs to keep doing that.
Such an error would be clumsy and thus unlikely but not impossible. That is why having a replicated experiment or at least a second set of eyes review all components in Mizuno's rig is important as he could have accidentally left off an important detail. That said, do we see anywhere that the active vs control run have used a different blower power circuit?
I would expect that even if the current sense resistor in series was inserted in the active runs, the blower voltage should have been measured across the blower motor, not the blower + resistor, and the sense current measured across the resistor; so that no guess needs to be made on the blower effective resistance. Better than a current sense resistor would be to put a current sensor in series as exists in a common digital multimeter (but one that collects data for the digital data recorder) and not use a sense resistor as a crude current measurement device.
It is ESSENTIAL that the control run and active run have as little changed as is possible between them. This includes any electrical component and ideally the reactor itself. I have always been uncomfortable that the calibration reactor is different than the control reactor for the initial published Mizuno R19 tests; and that there is essentially no control for the published R20 tests. Any change between control and active must be documented as fully as possible for conclusive proof of excess heat.
1)
The airflow calorimeter consists of an insulated, airtight box (Magic Chef HMCF7W2). The 3 inch foam insulation has been supplemented with Reflectix foil insulation radiant barrier.
I really like the insulated Magic Chef box. Great choice.
2) "The calorimeter is housed in a non-climate controlled space so the input air is controlled to be a constant input temperature. A modified heated blower (Conair 1875) is used with PID control to maintain input temperature, usually within a few tenths of a degree."
Good idea, but please also consider that even with the insulated box the difference in both ambient air temperature, and the temperature of the roof, the walls, and any HVAC blown air will make a small but measurable difference on the net heat transfer from the reactor/control to the outside.
3) Your documentation is _great_ in this thread. When it comes time for the paper, you can copy and paste this into your journal article.
Such an error would be clumsy and thus unlikely but not impossible. That is why having a replicated experiment or at least a second set of eyes review all components in Mizuno's rig is important as he could have accidentally left off an important detail. That said, do we see anywhere that the active vs control run have used a different blower power circuit?
I would expect that even if the current sense resistor in series was inserted in the active runs, the blower voltage should have been measured across the blower motor, not the blower + resistor, and the sense current measured across the resistor; so that no guess needs to be made on the blower effective resistance. Better than a current sense resistor would be to put a current sensor in series as exists in a common digital multimeter (but one that collects data for the digital data recorder) and not use a sense resistor as a crude current measurement device.
It is ESSENTIAL that the control run and active run have as little changed as is possible between them. This includes any electrical component and ideally the reactor itself. I have always been uncomfortable that the calibration reactor is different than the control reactor for the initial published Mizuno R19 tests; and that there is essentially no control for the published R20 tests. Any change between control and active must be documented as fully as possible for conclusive proof of excess heat.
Without fan voltage and current measurement , (without a MAF, etc) it is nearly impossible to determine if the air flow rate changes between experiments. The air flow measurement in the Mizuno calorimeter is one of the weakest points of that arrangement, IMO. Reduced airflow nets a higher delta T, all else being equal. It is the easiest way to fool the calorimeter based on my tests. The Albiston calorimeter fixes the weakest link with the MAF sensors.
The current sense resistor in the Mizuno calorimeter is in series with the fan in order to make a voltage signal for the data logger. In the Saito calorimeter photo, there appears to be no blower fan sense resistor, instead there is an adjustable DC power supply. In that case it is possible to feed and measure the reactor and calibration units the desired blower voltage and current directly. To match the Mizuno calorimeter characteristics, Saito would have to set the fan voltage to about 9V, not the total 10.45 V that the Mizuno calorimeter gets because the sense resistor is in series. However, it appears that the calorimeter is not fully assembled in that photo: the RTDs are still in a bag beside the electronics, and there is a blower fan gasket on the RH side of the calorimeter.
A current sense resistor in series with the blower performs some very useful functions. The voltage to the blower fan is proportional to air flow, and the current sense resistor voltage can show that the fan is in fact always on.
Although not fully tested by myself, it appears so far that changing the reactor/calibration device resemblance does not affect the outlet-inlet air temperature dT, if everything else remains the same. The calorimeter captures (most of) the input power no matter what the configuration of the heat source is. A 200 W resistor 10 cm long or a 20 x 50 cm steel cylinder with 200 W input react the same at steady state. It is quite difficult to get a 5 C dT above calibration without adding real heat.
Without fan voltage and current measurement , (without a MAF, etc) it is nearly impossible to determine if the air flow rate changes between experiments. The air flow measurement in the Mizuno calorimeter is one of the weakest points of that arrangement, IMO. Reduced airflow nets a higher delta T, all else being equal. It is the easiest way to fool the calorimeter based on my tests. The Albiston calorimeter fixes the weakest link with the MAF sensors.
The current sense resistor in the Mizuno calorimeter is in series with the fan in order to make a voltage signal for the data logger. In the Saito calorimeter photo, there appears to be no blower fan sense resistor, instead there is an adjustable DC power supply. In that case it is possible to feed and measure the reactor and calibration units the desired blower voltage and current directly. To match the Mizuno calorimeter characteristics, Saito would have to set the fan voltage to about 9V, not the total 10.45 V that the Mizuno calorimeter gets because the sense resistor is in series. However, it appears that the calorimeter is not fully assembled in that photo: the RTDs are still in a bag beside the electronics, and there is a blower fan gasket on the RH side of the calorimeter.
A current sense resistor in series with the blower performs some very useful functions. The voltage to the blower fan is proportional to air flow, and the current sense resistor voltage can show that the fan is in fact always on.
Although not fully tested by myself, it appears so far that changing the reactor/calibration device resemblance does not affect the outlet-inlet air temperature dT, if everything else remains the same. The calorimeter captures (most of) the input power no matter what the configuration of the heat source is. A 200 W resistor 10 cm long or a 20 x 50 cm steel cylinder with 200 W input react the same at steady state. It is quite difficult to get a 5 C dT above calibration without adding real heat.
1) I'm not disagreeing with you.
2) There are current measurement devices for digital data collector rigs that get rid of the need for the crude 3 ohm series resistor for current measurement. Fan power is simple DC current, not a complex high bandwidth waveform. Too much voltage drop relative to fan voltage.
1) I'm not disagreeing with you.
2) There are current measurement devices for digital data collector rigs that get rid of the need for the crude 3 ohm series resistor for current measurement. Fan power is simple DC current, not a complex high bandwidth waveform. Too much voltage drop relative to fan voltage.
There are plenty of ways to avoid complexity at the fan input. The main thing is that it does whatever it does consistently. For normal experiments it doesn’t need to be iron-clad, but as proof of excess it should be. Mass air flow sensors, manometers, etc., throw the book at it...
Reducing the fan voltage helps settle the outlet air velocity profile, which tends to be a jet in front of the forward side of the blower fan blade rotation. The overall air velocity-volume sets the range of delta T/W, so this can be tuned by fan speed also. Once a happy balance is sorted out, the fan power should left alone.
Using the interactive Power Flow Rate Visualized simulation here (scroll down a bit):
https://farnam-custom.com/resources/calculators
(Or some spreadsheet of your own, since the back-and-forth with SI and other units is a nuisance)
It should be possible to estimate the required air flow change necessary to ‘explain’ excess heat claimed in some of the data so far available, and see if it is reasonable within the scope of the blower power supply, etc., or equally ‘impossible’ as real heat generation from some unknown source.
Without fan voltage and current measurement , (without a MAF, etc) it is nearly impossible to determine if the air flow rate changes between experiments.
Are you talking about Mizuno or Albiston? In Mizuno's experiment the fan voltage and current are measured and recorded. The airspeed has been confirmed with two different aneometers, and it does not change, so obviously the fan speed could not be changing.
Why would it change, in any case? A small electric motor does not vary in performance. The size of the holes does not change.
The air flow measurement in the Mizuno calorimeter is one of the weakest points of that arrangement, IMO.
Again, assuming this is about Mizuno, I do not see why. And I do not see how he could improve it. He records V, I, and he confirms the air speed with two different aneometers.
Display MoreAre you talking about Mizuno or Albiston? In Mizuno's experiment the fan voltage and current are measured and recorded. The airspeed has been confirmed with two different aneometers, and it does not change, so obviously the fan speed could not be changing.
Why would it change, in any case? A small electric motor does not vary in performance. The size of the holes does not change.
Again, assuming this is about Mizuno, I do not see why. And I do not see how he could improve it. He records V, I, and he confirms the air speed with two different aneometers.
To summarize, the blowers in normal circumstances should not and generally will not vary their outputs with constant input. However the outlet airflow is one of the most critical measurements (calculations) and should be monitored directly as possible as continuously as possible. One cannot do handheld anemometers traverses all day, but a MAF, manometer, ect. can.
However the outlet airflow is one of the most critical measurements (calculations) and should be monitored directly as possible as continuously as possible.
Sure. Just leave the anemometer there, and either record it on a computer or jot down the readings every day. Who wouldn't do that? You have to have an anemometer to do this experiment, so you might as well leave it installed. You cannot be more direct than that!
If you get indications of excess heat, check it again. Use another anemometer. Who wouldn't do that? It isn't as if you are going to assume the heat is real without rechecking all parameters carefully.
One cannot do handheld anemometers traverses all day, but a MAF, manometer, ect. can.
There is no need to do a traverse every day! Do it once at the beginning of the test, after you seal up the calorimeter chamber. Once you confirm the flow rate is even across the face of the outlet, you know it will not change. Why would it? Nothing in this experiment can affect the blower or the size of the inlet and outlet orifices. They are left alone.
You should never change the air flow rate or pathway. It should be the same during all calibrations and all tests.
However the outlet airflow is one of the most critical measurements
Mizuno's experiment the fan voltage and current are measured and recorded.
note that the blower V, I readings have been truncated to two dp
note that the blower V, I readings have been truncated to two dp
By me. I don't like meaningless extra digits of precision. My late mother taught me use a slide rule, and said the beauty of it is, you can't even read beyond two digits, so don't worry about them. She and others of her generation thought that computers were excessively precise. A biologist I knew in the 1970s poked fun at a grad student who recorded the body temperatures of a rat to 4 digits, with the newly invented digital thermometer. If the rat exhales or farts, the last 3 digits will change randomly.
If the rat exhales or farts, the last 3 digits will change randomly
of course the subject may have ulterior motives... but that is an extinct thread..full of hotair.
in this case .. truncation to 2 dp has zero impact on the precision of the result..
Seeing and recording the noise in measurement data is important. It reveals the limits of the measurement instruments, and with careful analysis can be used to extract important data that is otherwise lost.
Sure. Just leave the anemometer there, and either record it on a computer or jot down the readings every day. Who wouldn't do that? You have to have an anemometer to do this experiment, so you might as well leave it installed. You cannot be more direct than that!
A hot wire anemometer with temperature correction calibrated to the entire outlet size is a Mass Airflow Sensor.
A hot wire anemometer with temperature correction calibrated to the entire outlet size is a Mass Airflow Sensor.
I don't quite understand. What do you mean "calibrated"? They don't fit the entire size of the outlet. The hot wire is too small. Only the vane type ones (propeller types) can do that, and I believe you are not supposed to make them as large as the orifice.
Do you mean tested in a traverse test?
I don't quite understand. What do you mean "calibrated"? They don't fit the entire size of the outlet. The hot wire is too small. Only the vane type ones (propeller types) can do that, and I believe you are not supposed to make them as large as the orifice.
Do you mean tested in a traverse test?
If the air temperature and velocity is constant across the outlet, then (in theory) a hot wire anemometer anywhere in the outlet area will read the same for the same airflow at the same temperature and density. From there it is only a hop, skip and a jump to working out a constant or equation that fits the anemometer response to the air velocity (mass) for the whole outlet. The only real trick is getting the outlet flow temperature perfectly mixed (not too hard) and the velocity constant (harder) across the whole outlet.
The sensing element in an automobile MAF is a hot wire that is rather small in comparison to the total area of the sensor body. Most of an automotive MAF sensor body is devoted to straightening and evening-out the air flow.
Edit: Technically, (and I have a manual that suggests this) one can map out the sweet spot on the anemometer traverses that matches the proper average consistently, and use that location for the reference location from there on.
