Monday, October 13, 2014

Auracher Nukiyama Boiling Analysis

Here is reference that may be useful.

Some Remarks on the Nukiyama Curve
Hein Auracher
Professor, Dr.−Ing.
Institut für Energietechnik
Techniche Universität Berlin

It was about 70 years ago when Shiro Nukiyama published his pioneering paper on “Maximum and Minimum Values of Heat Q Transmitted from Metal to Boiling Water under Atmospheric Pressure” [1]. A milestone at the beginning of a long way towards the “truth” in boiling heat transfer. Numerous researchers
discovered a lot on this way but the more we find out the more difficult it becomes to really understand this extremely complex process.

Basically Nukiyama’s boiling curve has never been disputed. Only specific aspects were and are subject of studies or disagreements. The shape of the boiling curve, for instance, is still a subject of discussions in terms of its behavior in the transition region, its change in a transient situation with respect to the steady-state case, its dependence on contaminations on the heating surface etc. 

The shape of the boiling curve and its change under
different system conditions is, of course, a result of different boiling mechanisms and their change. Since pure empirism can never solve such problems, several physical models for the different boiling modes have been developed. We should trust these models only after experimental verification. Moreover, due to the improvement of our experimental techniques and also of the mathematical tools in recent years, older and relative simple models can now be improved and new ones can be developed.

The present report makes some remarks on the aspects mentioned above. Of course not comprehensive and – subject of excuse – focused mainly on our own work. It is just meant as a small tribute to Nukiyama’s pioneering work. Those who need a sort of survey on new developments may look into the “Proceedings of the 5th Int. Boiling Heat Transfer Conf. in Jamaica, May 2003”. A selection of the papers presented there will soon be published in the “International Journal of Heat and Fluid Flow”.

No contradiction exists about a hysteresis in the region of nucleation incipience (see Fig. 1). In contrast, in transition boiling and for steady-state conditions a hysteresis was postulated [2] consisting of a transitional nucleate boiling–and a film boiling–branch, both overlapping with respect to the heat flux. However, if a precise temperature control system [3] is available and with a clean heating surface, boiling curves even for liquids with large contact angles (water) show no hysteresis regardless in which direction they are measured: stepwise from
film to nucleate boiling or vice versa. In contrast, if surface contamination is involved, boiling curves are not reproducible. Each test run, even under carefully established steady- state conditions, results in a shift of the curve already at a minimal change of the deposit [3,4].
incipience of
∆T = TW - Tsat
wall superheat
Fig. 1: The Nukiyama curve.

The boiling curve behavior log
changes under transient conditions,
even on clean surfaces. Recently it
was argued that “how the unsteady
process influences the hysteresis is not
cleared, yet” [5]. Objection! It is, as
shown by systematic experiments in
[6]. There, measurements with
controlled heating and cooling rates
were carried out, of course, by taking
into account the “coupling problem
[5]” between heater and fluid which
requires the solution of an inverse heat
conduction problem. One typical
result is shown in Fig. 2: The

steady-state curve was measured with 

JSME TED Newsletter, No.41, 2003

Saturday, October 11, 2014

Upton Sinclair Wisdom

"It is difficult to get a man to understand something, when his salary depends upon his not understanding it."

Sunday, October 5, 2014

Power Transformer Lifetime

Here is a reliable reference: 


Brian D. Sparling, Jacques Aubin
GE Energy
Power Transformer Reliability

Power transformers are essential components of transmission systems and often the most valuable asset  in a substation. Winding construction is based on the time-proven technology of copper conductor, wrapped in cellulose insulation, and fully impregnated with insulating oil. With a Mean Time Between Failure (MTBF) above 100 years, transformers are regarded as highly dependable equipment. However, the general transformer population is now aging. This by itself would increase the risk of failure but it is  compounded by the trend to load transformers to higher levels to meet economic constraints of deregulated power systems environment. 

Saturday, October 4, 2014

The Boiling Heat Transfer Laboratory at UCLA has been shut down.

Really, the Boiling Heat Transfer Laboratory at UCLA has very likely not been shut down.  However, its web page is unavailable, and that is unfortunate. 

I have made email requests for an explanation, here is the latest, but I have had no response.
Boiling Heat Transfer Laboratory
Date: 10/1/2014 12:44:11 P.M. Mountain Daylight Time
From: Send IM to:
Sent from the Internet (Details)
It has been a while since I contacted the Boiling Heat Transfer Laboratory; in fact, I was the first to contact that site a while back.  However, I have been trying for the past several weeks with no luck. So, what is going on?

Here is an entry to this blog from a while back.  The first two links yield prompt responses.  However the third link (to my paper) is unresponsive. And the fourth link (to the Boiling Heat Transfer Laboratory at UCLA) is also unresponsive.

Of course, I am not pleased.  


Boiling Heat Transfer Gang

I reported my great discoveries in abbreviated form during 2002:

Next, I intoduced UCLA (Dhir) to this field and I presented a more detailed paper at the Montego Bay Boiling Conference during 2003.

Leyse, R.H., Meduri, P.K., Warrier, G.R. and Dhir, V.K., “MICROSCALE PHASE CHANGE HEAT TRANSFER AT HIGH HEAT FLUX,” Proceedings of the 5th International Boiling Heat Transfer Conference, Montego Bay, Jamaica, May 4-8, 2003.

Previous Boiling Conferences and their corresponding chairs:

Santa Barbara, CA, USA
V.K. Dhir (UCLA)

Banff, Canada
J. Chen (Lehigh University)

Irsee, Germany
F. Mayinger (University of Munich)

Girdwood, Alaska, USA
A. Bar-Cohen (University of Minnesota)

Montego Bay, Jamaica
J. Klausner (University of Florida)

Spoleto, Italy
G.P. Celata (ENEA)