Quote:
Originally posted by Les
Silly me.
Had intentions of look-see at Impingement on my 6mm bped block
Have only just realised that I am probably on the upper bp thickness limit to get any improvement from impingement cooling.
Playing with data from http://www.electronics-cooling.com/h...01_may_a2.html (Ta Bill) and http://widget.ecn.purdue.edu/~eclweb/jet_benchmark/ (Ta g-f) suggests:
Speculative Performance
Intention 3mm noozle .Impingement Cooling Diameter 15mm (max) with h ~ 100,000W/m*m*c for 200LPH flow.
Think I need a thinner bit of Copper.
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When you actually do the sums* (add the "Jet Impingement" and the "Wall Jet" contributions) there is a possibly detectable difference even at 6mm:-
There is a predicted difference of possible more than 0.06C/W between the "Side-to-side" and the "Central Inlet" with h=100kw/m*m*c in the JIA and a 6mm bp
For a 70W Duron(50W Real) a 0.06C/W should be realised as ~ 3c which may or may not be detectable.
Edit: Added curve for the perhaps more realistic h=50kw/m*m*c in the Jet Impingement Area.
* Sums:-
Total Cooling = (Cooling from Jet) + (Cooling from Wall Jet) = Qj + Qw = C(Wj/Cj) + C(Ww/Cw)
Total C/W = 1/[(Wj/Cj) + (Ww/Cw)]
For a 15x15mm Jet Impingement Area(JIA), 6mm bp,and 200LPH through 3mm nozzle(h=100kw/m*m*c)
(Wj/Cj) is reciprical of "15x15mm Impinge Area" C/W value at 100kW/m*m**c on graph.
(Ww/Cw) taken as the difference betwwen recipricals of (50x50mm) and (15x15mm) C/W s at 100LPH(split flow).
(Wj/Cj) = 1/0.135 = 7.407
(Ww/Cw) = 1/0.199 - 1/1.06 = 5.025 - 0.943 = 4.082
Total C/W = 1/[(Wj/Cj) + (Ww/Cw) = 1/[7.407 + 4.082] = 1/11.489 = 0.087
For 12x12mm JIA,6mm bp,and 200LPH through 3mm nozzle(h=100kw/m*m*c):-
(Wj/Cj) = 1/0.182 = 5.495
(Ww/Cw) = 1/0.199 - 1/1.62 = 5.025 - 0.617 = 4.408
Total C/W = 1/[(Wj/Cj) + (Ww/Cw)] = 1/[5.495 + 4.408] = 1/9.903 = 0.101
Repeat for various bp thicknesses with a JAI Heat Trans Coeff (h)of 100kw/m*m*c.