email exchange with earlier Lienhard MIT

Subject:               Boiling on small wires

Date:     7/7/2020 8:11:52 AM Mountain Standard Time

From:    JHLienhard@Central.UH.EDU

To:          bobleyse@aol.com

Cc:          lienhard@mit.edu

Bob,

      This note did indeed find a circuitous route to the “earlier Lienhard.”   Thanks for taking the trouble to get it to me. 

       Your idea of suppressing the loss of nucleate boiling by pressurizing the system would be accurate.  What happens (as you know from Nanik Bakhru’s and my paper) is that the first bubble engulfs the wire.  That causes local burnout which then spreads into each neighboring bubble.   And no sustained nucleate boiling can endure. 

       Bubbles will be smaller at higher pressure, or, for that matter, at elevated gravity. So the matter of determining conditions at which nucleate boiling cannot occur becomes a matter of identifying, and putting to use, the correct scaling parameters.  The end of nucleate boiling will occur under different conditions, should you change the pressure (or gravity.) 

       In any case, it’s good to see someone looking into these matters.  Too many people ignore them.

               John (IV)

                

From: bobleyse@aol.com

To: GERVAISC@MIT.EDU
Sent: 7/6/2020 2:11:52 PM Mountain Standard Time
Subject: Please pass this on

Christine Gervais,

The following  likely relates to an earlier Lienhard, however, I would appreciate your drawing the following to the attention of the current J. H. Lienhard.  

 9th International Conference on Boiling and Condensation Heat Transfer 

MICROSCALE PHASE CHANGE HEAT TRANSFER TO WATER

Robert H. Leyse*

INZ Inc., P. O. Box 2850, Sun Valley, ID 83353

April 26-30, 2015 – Boulder, Colorado

bobleyse@aol.com

Bakhru and Lienhard4, 1972, asserted in their publication, BOILING FROM SMALL CYLINDERS, that, “Nucleate boiling does not occur on the small wires” and “Three modes of heat removal are identified for the monotonic curve and described analytically: a natural convection mode, a mixed film boiling and natural convection mode, and a pure film boiling mode.” However, although those wires are three to ten times the diameter of the 7.5 micron platinum wires of this work; this work clearly revealed nucleate boiling from the small wires. Balhru and Lienhard only performed experiments at low pressures; it would be a relatively easy experiment to deploy those wires at higher pressures in order to reveal a transition to nucleate boiling.

Bakhru, N. and Lienhard, J. H., Boiling from small cylinders, Int. J. Heat and Mass Transfer, vol. 15, pp. 2011-2025, 1972

Robert H. Leyse

Sun Valley, Idaho