Design Engineer Needed! Peltier Cooler Design Help!

Hello I’m new to the forum and also new to Peltier modules, heatsinks, CPU fans, and thermoelectrics. I need help figuring out how to efficiently match those components together to get the result I want. I have a basic understanding of wiring but I’m not an expert by any means. I’ve been more of a mechanical designer rather than an electro-tech designer. I’m pretty smart though so I think I can figure it out with some help. I am designing a DIY Aeroponic system and I need a way to cool my nutrient reservoir. My goal is to bring the temperature of a 3-5 gallon water container down from 85 degrees Fahrenheit to 50 degrees Fahrenheit. I found a device that I want to use but it was too expensive and wasn’t going to have the ability to cool as well as I want it to. so I decided to build one but be more efficient and effective. Here’s the link to the decide that I am trying to base my design off of:

The diameter of the probe is 1-1/4”. I thought about doing just a simple cooling plate but then I couldn’t seal it against a cooler or a plastic container as well as I could as a bulkhead style probe fitting. Well they don’t sell probes like that and no one else makes anything close to that kind of thermal transfer probe so I had to make one. Aluminum and Copper are the two best metals for transferring temp like I’m needing, I couldn’t find an aluminum bolt or all-thread in 1-1/4” diameter so I got a piece of 1-1/4” aluminum round bar and threaded one end to fit a flat aluminum flange and got an aluminum flat lock nut to seal it against the wall of the container. Basically the same probe, just DIY. I plan to use the aluminum flange of the probe as the thermal face that will contact the cold side of the Peltier module and transfer the cold temp down the probe and into the water. The flange is a 4-1/2” diameter circle so I want to find a Peltier chip that will fit under it nicely and be as cooling efficient as it can be. I need to cool a 3-5 gallon container from 85 degrees Fahrenheit to 50 degrees Fahrenheit but it’s going to have a controller so if the chip can cool more than that, it would be preferred because I might change the size of my reservoir and I want it to be strong enough to cool a larger size water tank or insulated box. If the module is able to cool it more than what I’m needing, the controller won’t have to run it as long, which would mean less power draw and it also wouldn’t be sending heat into the room. I don’t want to heat up the outside of the room the or closet that the container will be in, so I need to be able to dissipate the heat effectively as well. I could use those huge Heatsinks with two and three fans with pipes that looks like a hot rod engine, but since the Peltier device will be sitting on the side of the water tank, the heatsink can’t be very heave or stick out very far. So I need to match the Peltier module with a heatsink and CPU fan that will effectively cool the Peltier module that I’m looking for. since it will be cooling with so much force, it will also be heating with a lot of force and like I said, I don’t want to heat up the room so I was thinking about using a heatsink like this:,ss:44&prmd=sivn&sxsrf=ALeKk02wST30IOo2hK7zmStKgUnU86Q0dQ:1593026927993&prds=epd:11304467210571878547,cdl:1,prmr:1,cs:1

I thought of this heatsink because it is thin and won’t be hard to mount on the side of a container and it has the cooling pipes like the bigger brothers to it that look like the hot rod engines. The Peltier module also has to fit on the heatsink plate so I have to consider the size of the heatsink that I will need to fit a Peltier module of the size I need. Since the device will be close to water, I was hoping to find a waterproof module or find something that will seal it up so water can’t get to the electronics. I am buying thermoelectric epoxy glue, could that be used to seal all under and around the Peltier module to make it waterproof? Or maybe a pad to go around it that makes it waterproof? I don’t know much about CPU fans but I was hoping a heatsink like from the link with the fan would be okay to withstand the heat of the Peltier module. I know some CPU fans can’t take that much heat. I think the fan and the Peltier module have to work on the same power, so I have to make sure that when I wire the red wires from the Peltier and fan together and the black wires from the fan and Peltier together that the power supply is going to make them both run as they are intended to be and not overpower one and underpower the other. Since I’m using a controller, the fan and Peltier module have to match the power of the controller so I have to find a controller that will be easy to set up and control my Peltier cooling device. As you can tell, I’m a beginner but I’m trying to learn. I really appreciate anyone who reads and comments on my questions and concerns. Finding a good module for cooling that is efficient and effective at the same time that fits the size parameters I’m looking for is one thing when you are an expert, but for a beginner, everything is Greek and I’m having a hard time understanding all the technical information about them. Thank you all for any help I can get.


The resources below might be useful; they walk through the process of understanding what the thermoelectric device specifications mean, and how to use that information to make an informed estimate of what’s possible and what’s not. A third segment is in the works…

Just to offer fair warning here, I’ve observed an almost universal tendency for folks to seriously overestimate the cooling capacity of thermoelectric devices until they take the time to learn the Greek and do the math… TEMs have a lot of useful traits, but efficiency is NOT among them. By the time one’s speaking of a 3-5 gallon volume, adapting a small (standard) refrigerator to the task is likely to give a much more satisfactory result.