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Just to be clear, the title got put there because of the manner in which aenigma responded to a moderator. It's fine to disagree with the moderators! Joe was trying to discourage (in a humorous way) the way that it was done. I have since requested that Joe to change the title back, but it hasn't gotten done yet.
I don't want any polite discussion to be discouraged, and I know that Joe does not either. Misunderstanding someone can easily lead to unintended hurt feelings and rude interaction (and that definitely includes us human moderators).
Take home message: We're all working towards a perfectly friendly and informative group forum, but we humans have a ways to go.
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Now, having said that, -19C surely isn't bad! Last I checked, that may be better than most heatsink or even waterblocks.
As for slugging, wouldn't it be possible to add a TXV (thermal expansion valve)? Yes, most TXV's are designed for much higher loads, but you could create a higher heat load by letting extra heat into the chiller loop after the evaporator and before the TXV superheat sensor. Cool the interior air to the case, for example. Alternatively, would a short length of capillary tube after the TXV help reduce valve flutter by creating a base restriction level?