First I would add to my previous message, that I think that Peter's method
is more accurate than measuring pressure. That is because in order to find
out correlation between pressure and enthalpy we need to do very careful
calibration. In short run high accuracy may be difficult to archieve, but if
experiment lasts for example 10 years continuously, then of course
calibrating pressure sensor for enthalpy calculations will give great pay
off.
Horace wrote:
« You have again not specified the precise method you would use.
It would appear you have a case of missing variables. The principle missing
variable is mass flow, m dot, which is best to isolate and measure directly.
»
Actually I have defined but it is so simple that you have probably missed
it. First of course, we need to know that system is at equilibrium, i.e.
water massflow in and massflow out are both matching. If water inflow rate
varies a lot then calculations and calibrations are difficult, if system is
overflowing. That means that for sure massflow must be known and it must be
measured in calibration.
But if system is a kettle boiler that does not overflow, then calibration is
very easy. In industrial water boilers this is the most reasonable situation
because this ensures high steam quality because we can easily superheat
steam to remove that 1-2% natural wettness of steam. This reduces the
corrosion. Superheating can also be considered in calculations so this does
not reduce the accuracy of method.
Pressure can be measured either directly with pressure sensor (easiest and
most reliable and it is always available in pressure boilers.) or in kettle
boilers boiling water temperature can be measured or last method is to
measure steam temperature (this works only if steam is not superheated and
is thus wet. I.e. steam quality must be measured, therefore this method is
not universal).
—Jouni
On Sep 28, 2011 7:41 AM, "Horace Heffner" <hheff...@mtaonline.net> wrote:
>
> On Sep 27, 2011, at 9:35 AM, Jouni Valkonen wrote:
>
>> 2011/9/27 Peter Gluck <peter.gl...@gmail.com>:
>>> The simplest solution is to use a Steam Water mixing valve,in
>>> which the
>>> heated mixture coming out from the demo is mixed with a constant
>>> flow of
>>> cold water, you can know the enthalpy performance in any moment.
>>
>> Indeed, continuous experiments easiest way is to use enthalpy sensors,
>> that gives as total enthalpy for any given moment. Even more simple is
>> to measure the steam pressure inside E-Cat, because it gives directly
>> the total enthalpy, but of course we need to first calibrate this kind
>> of enthalpy sensors.
>>
>> –Jouni
>>
>
>
>
> You have again not specified the precise method you would use.
>
> It would appear you have a case of missing variables. The principle
> missing variable is mass flow, m dot, which is best to isolate and
> measure directly.
>
> Best regards,
>
> Horace Heffner
> http://www.mtaonline.net/~hheffner/
>
>
>
>
