Heat transfer for forced convection on a plate (NOT across a plate) 1

[imagitec]

I'm looking for relevant calculations for forced convection on the face of a finite plate. There is plenty of information about forced convection across a plate, like a PCB cooled by a fan. Definitely not what I'm looking for.

The application is a vehicle-mounted optical window to be heated electrically to keep frost from forming.

Thanks,
Rob

 

[IRstuff]

Then, it's not convection, it's conduction. The relevant standard, containing more than you'll EVER want to know about the subject, is SAE AIR 1168-4 Ice, Rain, Fog, and Frost Protection.

Specifically, 10.3.1 Electrical Anti-Icing, Table 3F-3 shows values of windowing heating ranging from 2.44 W/in^2 to 4.26 W/in^2 for cruise speeds ranging from 100 kt to 300 kt, respectively. The numbers do NOT include heat losses to the cabin interior.

TTFN

FAQ731-376

 

[imagitec]

Thanks for the reference. I'll look into it, but the numbers you cited might be enough for my immediate needs. Do they reference temperature ranges in the same table? The low temperature spec is around -40 C.

I've always thought of convection in terms of conduction to a fluid aided my mixing and buoyancy. This seems to meet those criteria. Why would you classify this case as conduction instead?

A little more Googling and stumbling around led me to the term impingement cooling, which seems closely related. Still, there is little readily available on the subject.

Thanks,
Rob

Rob Campbell, PE
Finite Monkeys -

http://www.livejournal.com/users/robcampbell

 

[IRstuff]

The cooling of the window is forced convection, but the heating is not. From your posting, it sounds like you want to heat the window electrically, hence, conduction.

SAE 1168-4 covers all regimes of flight, I think including supersonic. The basic objective is to raise the temperature of the window to just above freezing, and the heat required is dependent on the airstream velocity, but the heat required starts dropping as you get closer to transonic, since you then start to get substantial aeroheating and the windows won't need additional heating.

TTFN

FAQ731-376