# Error bounds for Mizuno R19 results

• This is a mystery - the paper says

In Figure 8.. the written explanation of motor heat is not correct..IMHO.

There is no mystery in Figure 8

It should be waste heat from the blower.. rather than waste heat from the motor

if one defines blower waste heat as due to the blower blades heating of the air.

The actual kinetic energy pushing the flow forward amounts to only Pk= 0.15W out of the total 5W

Assuming electric motor efficiency 93%/87%

Power input 5W

Motor waste heat total= 0.35/0.65

Motor waste heat to outside = 0.1??

Pk =Power Mass flowratex Vsquared/2 (0.016x1.178kg/m3x4squared/2 =0.15W)

Blower “turbulent” waste heat to fan air = 4.5/4.2W

Motor waste to fan air=0.25/0.55W

Total Thermal heat in fan air-??

Mass Flowrate x Cv x delta T (0.016x1.178kg/m3x717.8 x 0.35=4.75W)

• RB - what you say is all fine, and agreed by me (I've said it myself) except for the part of my previous posts you have not yet addressed.

That is why I suggested higher motor heat loss: but it remains something of a mystery. Perhaps LEMHR? (a low energy motor heat loss effect

elusive and only found in calorimetry experiments with the exact correct voltage, current and torque for teh motor).

In the 1st paper we have pp8-9:

The blower is operated at 6.5 W. The outlet air temperature is measured with two RTDs. They are installed in thecenter of the pipe,

one in the stream of air before it reaches the blower, and one after it, to measure any heat added to the

stream of air by the blower motor. The difference between the two is less than 0.1◦C. However, there are indications
that heat from the blower motor is affecting both of them.
A calibration with no input power to the reactors shows that
when the blower power is stepped from 1.5 to 5 W, the outlet RTDs are ∼0.35◦C warmer than inlet (Fig. 8). This is a
much larger temperature difference than the moving air in the box alone could produce.
Blowers are inefficient, so most of the input power to the blower converts to waste heat in the motor. It seems likely
some of this heat is conducted by the pipe to raise the temperature of the two outlet RTDs.

• so most of the input power to the blower converts to waste heat in the motor

RB - what you say is all fine, and agreed by me

On the contrary apparently it is not agreed by THHnew

Most of the 5W input power to the blower does not convert to waste heat in the motor - about 7-13% only .. or 0.35 to 0.65W

Most of the input power to the blower converts to thermal heat in the blower air. 4.2 to 4.5W

which accounts for most of the 0.35 C temperature rise.

IMHO

• RB, please address the part of my last post which you deleted in that quote?

• RB, please address the part of my last post which you deleted in that quote?

Please address the stuff you asserted you agreed with but in fact did not.

On the contrary apparently this stuff is not agreed with by THHnew

THHNew : so most of the input power to the blower converts to waste heat in the motor

Most of the 5W input power to the blower does not convert to waste heat in the motor - about 7-13% only .. or 0.35 to 0.65W

Most of the input power to the blower converts to thermal heat in the blower air. 4.2 to 4.5W

which accounts for most of the 0.35 C temperature rise.

IMHO

• 3. As I described above, output heat fluctuations in a recent test are not correlated with input power. If the apparent excess heat was caused by an input power misreading, this could not happen. Along the same lines, the same input power with different meshes causes drastically different levels of output, and often no output at all. It changes over time, responding to loading and deloading.

Do you have a chart of this? Best to plot input power on X and apparent excess on Y instead of time on X and input power and excess on Y. You can see the relationship much better with the former method.

• RB: Please address the stuff you asserted you agreed with but in fact did not.

THHNew :

So most of the input power to the blower converts to waste heat in the motor

Most of the 5W input power to the blower does not convert to waste heat in the motor - about 7-13% only .. or 0.35 to 0.65W

If you read my previous post you will see that I highlight this issue as an anomaly - well represented by these two contradictory statements. If the motor is 10-15% efficient, then how can the upstream temperature sensor be 0.35C hotter as well as the downstream sensor?

Whereas, if most of that 80% power is dissipated in the motor it makes sense. However I'm quite prepared to believe what you say (because I have not checked, and you say you have) about no fan motor of this size being so inefficient. It is anomalous, and thus deserves further investigation as I've repeatedly said.

• The issue about varying calorimeter efficiency would come from heat losses or RTD errors (as documented by you in the paper) varying with reactor position.

You can ignore "efficiency" (the recovery rate). It is icing on the cake. There is massive excess heat even when you ignore it, far above the margin of error. So, if you have doubts about it, multiply total heat by 0.75. The RTD readings do not vary with the reactor position. I did not say anything about that in the paper. You dreamed that up. It is ridiculous.

Robert Bryant pointed out to me that the slight increase in temperature during a test with no input power is probably caused by the blower stirring the air, rather than by waste heat from the blower motor.

• Robert Bryant pointed out to me that the slight increase in temperature during a test with no input power is probably caused by the blower stirring the air, rather than by waste heat from the blower motor.

Jed,

I am surprised that others here do not pay attention to the facts recounted in the 1st paper, but more surprised that you, (who translated it?), forget this (copied from #43)

In the 1st paper we have pp8-9:

The blower is operated at 6.5 W. The outlet air temperature is measured with two RTDs. They are installed in thecenter of the pipe,

one in the stream of air before it reaches the blower, and one after it, to measure any heat added to the

stream of air by the blower motor. The difference between the two is less than 0.1◦C. However, there are indications
that heat from the blower motor is affecting both of them.
A calibration with no input power to the reactors shows that
when the blower power is stepped from 1.5 to 5 W, the outlet RTDs are ∼0.35◦C warmer than inlet (Fig. 8). This is a
much larger temperature difference than the moving air in the box alone could produce.
Blowers are inefficient, so most of the input power to the blower converts to waste heat in the motor. It seems likely
some of this heat is conducted by the pipe to raise the temperature of the two outlet RTDs.

• You can ignore "efficiency" (the recovery rate). It is icing on the cake. There is massive excess heat even when you ignore it, far above the margin of error. So, if you have doubts about it, multiply total heat by 0.75. The RTD readings do not vary with the reactor position. I did not say anything about that in the paper. You dreamed that up. It is ridiculous.

I'm sorry, but this time I have to agree with JR. It is ridiculous to question the "icing on the cake", when you don't even know if the cake is real.

• If you read my previous post you will see that I highlight this issue as an anomaly - well represented by these two contradictory statements. If the motor is 10-15% efficient, then how can the upstream temperature sensor be 0.35C hotter as well as the downstream sensor?

Whereas, if most of that 80% power is dissipated in the motor it makes sense. However I'm quite prepared to believe what you say (because I have not checked, and you say you have) about no fan motor of this size being so inefficient. It is anomalous, and thus deserves further investigation as I've repeatedly said.

THHuxleynew : Such reasoning usually leads to the question "how many beers.."

A motor usually does convert power (electric --> mechanic) and not dissipate it. The conversion efficiency of motors usually is higher than 90% since a long time now. You can call e.g. <10% dissipate. But according to basic laws all energy of free airflow ends up in the air or in friction with material.

In Mizunos case the turbulent part of air movement is seen as regular increase in T. How we must account for the kinetic part I did not look up, as it depends on the type/shape of thermometer used and the losses (friction) to the wall. But the turbulent part can be calculated from airspeed, motor efficiency and delta T - if a friction free measurement is done by using e.g. a tiny thin piece of metal and an optical thermometer reading it's surface.

• [QUOTE FROM PAPER] The blower is operated at 6.5 W. The outlet air temperature is measured with two RTDs. They are installed in thecenter of the pipe,

one in the stream of air before it reaches the blower, and one after it, to measure any heat added to the

stream of air by the blower motor. The difference between the two is less than 0.1◦C. However, there are indications
that heat from the blower motor is affecting both of them.

The 6.5 W was either a misprint, or he is now using a new blower which takes less power. Those blowers wear out.

I now think the heat from the fan stirring up the air was the cause of the slight temperature elevation. Mizuno and I spent a lot of time looking at the data and measuring various things, trying to track down the source of it. We talked about the friction of air moving through the box, which is negligible. It did not occur to us that it was probably the fan blades stirring the air. We should have thought of that!

• The 6.5 W was either a misprint, or he is now using a new blower which takes less power. Those blowers wear out.

I now think the heat from the fan stirring up the air was the cause of the slight temperature elevation. Mizuno and I spent a lot of time looking at the data and measuring various things, trying to track down the source of it. We talked about the friction of air moving through the box, which is negligible. It did not occur to us that it was probably the fan blades stirring the air. We should have thought of that!

(1) Jed - how can the temperature of the RTD BEFORE the fan be affected by fan blades stirring the air???

(2) OK - so if a new blower is being used - WHY IS THE OLD BLOWER CALIBRATION BEING USED TO DETERMINE AIR VELOCITY?

None of these things are a big deal. But checking details as best can be done, with honesty, is always helpful.

What causes my capitals is apparent avoidance of fact checking when I have raised issues 3 times or more and you, RB ignore them and misrepresent my point.

• how can the temperature of the RTD BEFORE the fan be affected by fan blades stirring the air???

However, there are indications
that heat from the blower motor is affecting both of them. Rothwell.

THHnew you have to address Jed on what he means by indications,, that you say means the blower motor affects both inlet/outlet RTDs.

If the indications have numbers attached then calculations are possible.

If they are rationalisations without numbers then calculations are not possible.

My calculations are based on the inlet/outlet delta T of 0.35C with only blower input power of 5W.

These show that there is no mystery as you formerly intimated.

The temperature rise of 0.35C is mostly due to fan blade kinetic energy transfer to thermal energy in the airstream

rather than motor heat loss energy.

I am glad that you now agree with this ., and that Jed does too

This is such an interesting topic.

The maths for temperature rise is done well by a Nederlander and is over fifty years old.

• (1) Jed - how can the temperature of the RTD BEFORE the fan be affected by fan blades stirring the air???

Obviously I was referring to the RTD after the fan.

(2) OK - so if a new blower is being used - WHY IS THE OLD BLOWER CALIBRATION BEING USED TO DETERMINE AIR VELOCITY?

It is not! Who would do that?? When you change out any part of the calorimeter, you have to recalibrate.

Really, where did you get the idea that the old blower calibration is used? Where do you get these weird ideas?

• We should have thought of that!

You are forgiven... THHnew too.. we are all mortals..

Perhaps there are more important things to think about.

Maybe Paradigmnoia can check the temperature rise with some RTD's after going bush,

• (1) Jed - how can the temperature of the RTD BEFORE the fan be affected by fan blades stirring the air???

Ah, ha. I think I see what you mean. I forgot that one of the RTDs is before the fan. If that one is also affected, I guess that rules out the fan blades as the source of the heat.

I will have to have to look into this.

• THHnew you have to address Jed on what he means by indications,, that you say means the blower motor affects both inlet/outlet RTDs.

If the indications have numbers attached then calculations are possible.

If they are rationalisations without numbers then calculations are not possible.

My calculations are based on the inlet/outlet delta T of 0.35C with only blower input power of 5W.

These show that there is no mystery as you formerly intimated.

The temperature rise of 0.35C is mostly due to fan blade kinetic energy transfer to thermal energy in the airstream

rather than motor heat loss energy.

RB - I have quite lost patience with your repetition here.

How about you go back to my original post (before you deigned to take an interest) when I quoted Mizuno's paper and based my comments not on theory or my calculations but on what that said about experimental measurements made on the system.

I've now quoted it twice, and you have ignored it consistently, not addressing the key issue.

How can air heated up by the blower heat up the RTD upstream of the blower.

You, perhaps, know more about the apparatus than Mizuno in his paper, since he suggested that this was through conduction from the blower. There is no disagreement, not did I ever cavil, about the power into the blower causing this rise. The question is how that heat can get to the upstream RTD. Once in the airstream it will rapidly travel downstream for the fan.

As have said, this is a (relatively minor) mystery. I can't see what is your point here - except to ignore the anomalous data.

• Jed - I am at a loss here to decode the gnostic utterances from you.

The recent paper refers to an old calibration curve for the blower. If the blower has been changed, that would no longer be valid. I did not expect this, but if you now say that is true, then obviously i accept your new information as more accurate than the paper.

The outlet air temperature is measured with two RTDs. They are installed in thecenter of the pipe,

one in the stream of air before it reaches the blower, and one after it, to measure any heat added to the

stream of air by the blower motor. The difference between the two is less than 0.1◦C. However, there are indications
that heat from the blower motor is affecting both of them.

The Mizuno paper was referring to the RTD before the fan, which also had this 0.35C increase. Maybe that comes from something other than the blower. It should be viewed as unexplained, and perhaps the best solution then is not to worry but note a power measurement uncertainty from this system of at least 0.35C (scaled by the temperature -> power conversion). That is not a big deal.

It annoys me, i like to understand everything, and things not understood can end up having unexpected consequences.

THH

• Maybe that comes from something other than the blower

I admire persistence.. it could be useful for elucidating some of the mechanism of the reactor.

The 0.35C rise in Figure 8.. is mostly from the blower .. IMHO

The adiabatic temperature rise due to the pressure rise corresponds to something like 0.25 C.

You might like to check the calculation out for a pressure rise of 300 Pa.

On the other hand Jed's indications are unclear and not numerical as yet.

Any thermal rise before the blower must come from something else than the blower.

agreed.

and most probably not from the motor as Jed+TM wrote.

I have asked Jed about it.. since the raw spreadsheet for 2017 is unclear to me as to which RTD is which.

Jed may need to check with several of the spreadsheets..

these are not accessible to me.

Jed may let it simmer for awhile .. perhaps getting stuff ready for Assisi.

There may be many more questions on many aspects at Assisi than he has time to answer.