1. T HE C OOLING E FFECTS OF V ARYING W ATER D ROPLET V OLUME AND S URFACE C ONTACT A NGLE W ITH A M ETAL S URFACE I N A S TEADY S TATE, H IGH T EMPERATURE A IR F LOW Project Proposal MANE 6970 Matthew Noll March 12, 2015

2. INTRODUCTION This project analizes the effects of changing physical parameters of a water droplet on the evaporative cooling of a flat metal plate in a high temperature air flow.

3. BACKGROUND Cooling a high temperature air flow, such as the exhaust flow from a stationary natural gas turbine generator, normally requires spray cooling with droplet sizes on the scale of atomized particles. System limitations may limit the ability to produce an atomized droplet spray. Cooling system pressure limits Spray nozzle availability Water quality available for cooling spray Evaporative cooling provides the potential to maintain materials and components that are located in high temperature air flows at much lower temperatures without the need for an atomized spray.

4. METHOD

5. APPROACH (CONT.) When modeling the evaporation of the droplet in COMSOL, the time step is assumed to be very small and therefore is seen as a snapshot in time. The volume of the droplet will be changed by changing the radius of the hemisphere that is bounded by the wall.

6. POSSIBILITIES FOR SCOPE EXPANSION Although the “snapshot” analysis will give accurate values for heat transfer and metal surface temperature, the actual boundary of the liquid droplet is constantly shrinking as it is evaporated. COMSOL has multiple modules which can be used to analyze a system with a moving boundary, which can be applied to this case.

7. REFERENCES 1.Pressurizer Heater Material Issues in the Nuclear Industry Project Proposal, Daniel B. Denis, March 12, 2014 2.C OMSOL E XAMPLE, Evaporative Cooling of Water: (https://roundcube.rpi.edu/roundcube/?_part=4&_action=get&_mbox=INBOX& _uid=977&_task=mail) 3.S PRAY E VAPORATIVE C OOLING TO A CHIEVE U LTRA F AST C OOLING IN R UNOUT T ABLE ( HTTP :// WWW. SCIENCEDIRECT. COM. LIBPROXY. RPI. EDU / SCIENCE / ARTICLE / PII /S12900729090001 92) 4.Numerical simulation of accident spray cooling system in FGD system inlet (http://eds.a.ebscohost.com.libproxy.rpi.edu/eds/pdfviewer/pdfviewer?sid=8b8 1cb50-a6fa-447d-8bb4-cc979b945368%40sessionmgr4004&vid=3&hid=4102) 5.Fundamentals of Heat and Mass Transfer, Wiley 2011, Hoboken NJ, 07030-5774