Math help on single vessel chiller idea?

[officeboy]

Trying to work out what type of cooling "power" is needed to reasonably control fermentation temperatures. Here is the basic idea.

Brew bucket or bigmouth fermentor with a 1/4 or 3/8 stainless loop, hooked up to a small glycol pump that does 70l/hr. Heat exchange with a PC watercooling block (built into the pump) sandwiched with a TEC cooler and a regular PC heatsink on the other side.
I think I need 75-80 btu/hr to be able to control fermentation reasonably

5.5gallons x 8.33 = 45.815lbs x 40 deg temp drop to cold crash = 1834 btu / 24 hr crash period = 76.4 btu/hr​

But I don't know where to start to see if 70l/hr (or less with the 12ish inches of head) or if a 90W peltier cooler can get me into the 80+ BTU range. Anyone know where to start with that?

 

[officeboy]

I found the formula for calculating pump needs, GPM = BHTU / (Load factor density of liquid) X Temp Drop
So with an estimated temperature drop of 40F, and the density of Propylene Glycol at 40F = 436. I get 17,440, that divided into an expected 80 btu/hr = 0.0125 GPM. or 3/4 gal an hour... soo slow.