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Since87 · 09-27-2003, 01:10 PM

Interesting (to me) observation:

Extrapolating Bill's data - the MCW5002 has a lower C/W than White Water with flowrates a bit lower than 1 lpm.

I predict a thermal resistance of ~.255 C/W at 0.1 lpm for an MCW5002 and ~.285 C/W for a White Water at 0.1 lpm. (Inasmuch as these numbers have any relevance, it is WRT Bill's die simulator.)

I don't really want to go into a detailed explanation of how I came up with these numbers. In brief, I used my 'hydropower' spreadsheet to make fairly straight lines on a log graph out of the C/W vs 'hydropower' curves, and then extrapolated those lines to the 0.1 lpm point.

Warning: Mathematical nightmare approaching.

Some points for consideration:

A 226 Watt TEC is actually a two dimensional array of many smaller 'tecs'. Each of these small 'tecs' can be operating at a different point of the dT vs Q tradeoff. Thinking of a 226 Watt TEC as a single monolithic block works reasonably well when 'high' flowrates are used, because of the small dT between inlet and outlet coolant. As the flowrate is lowered, it becomes increasingly important to consider the operating dT and Q of the smaller 'tecs' within the TEC.

Edit: I'm just beginning to think about a grossly simplified model that attempts to consider the points above, and my head already hurts. There's a lot to be said for finding things out experimentally.

09-27-2003, 01:10 PM	#127
Since87 Pro/Guru - Uber Mod Join Date: Sep 2002 Location: Indiana Posts: 834	Interesting (to me) observation: Extrapolating Bill's data - the MCW5002 has a lower C/W than White Water with flowrates a bit lower than 1 lpm. I predict a thermal resistance of ~.255 C/W at 0.1 lpm for an MCW5002 and ~.285 C/W for a White Water at 0.1 lpm. (Inasmuch as these numbers have any relevance, it is WRT Bill's die simulator.) I don't really want to go into a detailed explanation of how I came up with these numbers. In brief, I used my 'hydropower' spreadsheet to make fairly straight lines on a log graph out of the C/W vs 'hydropower' curves, and then extrapolated those lines to the 0.1 lpm point. Warning: Mathematical nightmare approaching. Some points for consideration: A 226 Watt TEC is actually a two dimensional array of many smaller 'tecs'. Each of these small 'tecs' can be operating at a different point of the dT vs Q tradeoff. Thinking of a 226 Watt TEC as a single monolithic block works reasonably well when 'high' flowrates are used, because of the small dT between inlet and outlet coolant. As the flowrate is lowered, it becomes increasingly important to consider the operating dT and Q of the smaller 'tecs' within the TEC. Edit: I'm just beginning to think about a grossly simplified model that attempts to consider the points above, and my head already hurts. There's a lot to be said for finding things out experimentally.