DIY Thermoelectric Peltier Refrigeration

[Nightjar]

Thanks DD,
That's a much newer Engel, the old versions like mine do not have the exposed connections like that one. Have decided not to strip it down to get into the workings. Currently use a Engel wireless thermo, sender in fridge and I can monitor in the cab while travelling
Our second fridge is the 60L which already has the digital thermo which is actually a PIA because you need to climb onto back of ute to read it.
On long bush stays when we clean out the frozen meat in the 39L it is shut down and I then swap the sender into the 60L.
Have a second wireless sender in caravan fridge and can also monitor that one from cab while travelling.

 

[ctxkid]

mine arrived today , gotta love postage from china

hastily setup little fan shate itself in minutes but it does cool water

i'll get a new fan in the morning and put a few of my twists on it :Y: it has potential

still worx without the fan

 

[Nightjar]

CTX, Are you recycling the water to cool it for drinking?
My project is on hold for the moment Spring has sprung and spending all my free time in garden.

 

[ctxkid]

CTX, Are you recycling the water to cool it for drinking?.

yes it will be drinking water

 

[ctxkid]

New fan and running nice now, bit power hungry though

Might have to get a less greedy pump

 

[ctxkid]

The peltier is larger in your kit ?????

 

[Nightjar]

Yes, I see you are using a 12V shower pump that hogs a few amps.
My kit doesn't have water flowing through it. Did think the water was to help cooling, but then again didn't read closely.

 

[ctxkid]

Yes, I see you are using a 12V shower pump that hogs a few amps.
My kit doesn't have water flowing through it. Did think the water was to help cooling, but then again didn't read closely.

it pull 1.6 amp , so yeah i can get that down some , and decrease flow will get the water colder going trough the cooler

 

[Ded Driver]

I see a couple of these units on eBay that have a large heatsink & fan on the hot side, & a smaller (about half the size) heatsink & fan on the cold side, with no water adaptor, & although no doubt the water would help with the efficiency, it comes at the cost of more power consumption for a pump.
If a water cooled system is used, I am thinking that by careful positioning/elevation of the water-air heat exchanger at the end the piping (with a small fan), the pump could be left out & just rely on thermal circulation of the water (hot water rises, colder water from the bottom flows back to the peltier unit.
the trick would be to have the hot side piping higher, but not too high, & the cold return slightly higher so it gravity feeds cooler water back.

 

[Nightjar]

I see a couple of these units on eBay that have a large heatsink & fan on the hot side, & a smaller (about half the size) heatsink & fan on the cold side, with no water adaptor.

DD That's the one I bought, pics in earlier posts.
Have been wracking the brain how to switch the Peltier on/off.
Think I'm on a winner, good old eBay again, two units delivered to my mail box ($5.00)
Found the operating instructions using Google.
Just copy/paste heading into eBay search and you'll find them.

https://www.herman-shop.com/PDF/thermostat w1209 instruction.pdf

First thoughts are I set the Peltier up blowing through one of the vents directing cooler air over the workings of the Engel.
Just experimented in the shed setting the thermostat to 30C, held the sender between my fingers and the readout soon jumped to 30C and the Peltier powered up. Let go of the sender and the temp dropped to 27C (This is the norm for the Thermo, 3 below set temp. to prevent excessive energising) and the Peltier de-energised... (Ambient temp in my shed today is 21C
May set it up this way so if the ambient temperature rises to set temp while we are away prospecting the Peltier will kick in helping the fridge used as a freezer to maintain the low temps required to keep food safe.
Thinking thinking..

 

[Ded Driver]

that's the idea I had in mind too Nightjar.
The water cooling add-on isn't something I'd use inside a vehicle or van that does long km on rough roads or tracks.
I think any amount of cooler air blown into the fridge air intake will make a noticeable difference.
As my Aux battery & IDC45 charger are in a (not fully closed) compartment below the false floor, I reckon this setup will be good in there too. I have bought a high/low temp fan controller & was going to simply set that up, but am now considering a Peltier setup with it, & to be able to switch the fan with or without the Peltier unit.

 

[Nightjar]

Watch this space:
Have wired the thermostat and Peltier and running tests today using my old Engel.
Will get photos and details later.

 

[ctxkid]

i have made them work much cooler by water cooling the hot side

 

[Tathradj]

I have used these a few times.
Very good value.
Search the item number in Ebay,
362746301007

 

[ctxkid]

I have used these a few times.
Very good value.
Search the item number in Ebay,
362746301007

thanx doug , some coming my way , look good for the money

 

[ctxkid]

If a water cooled system is used, I am thinking that by careful positioning/elevation of the water-air heat exchanger at the end the piping (with a small fan), the pump could be left out & just rely on thermal circulation of the water (hot water rises, colder water from the bottom flows back to the peltier unit.
the trick would be to have the hot side piping higher, but not too high, & the cold return slightly higher so it gravity feeds cooler water back.

tried and the cold side losses efficiency , the cooler you get the hot side , the better, mine slowed as the water got hotter but it makes a better hotwater service than the $350 copperhead jobbie i bought recently :8
i am going to get more , and have one cooling the water entering the hot side , an the cold side should get mega cold on the third one, for 50 bucks it will be a fun experiment :Y:

 

[ctxkid]

i have thought about this most of the day , and now to find this, confirms my present experiments are on the right track erfect:

this is the power of water cooling the heated side :fire:

https://cloud.video.taobao.com/play/u/2027934439/p/1/e/6/t/10301/223647030102.mp4

might try glycol next :idea:

 

[Nightjar]

This set up was in my shed running the Engel on 240V.
Obviously the ute solar wasn't connected. You can see the Peltier was drawing 4 amps. (This gauge reads the in & out amps)
Can manually set the thermostat, (Bought two through eBay, $10.00 in my letter box) in this instance I temporarily set the cut in temperature at 22C.
The fridge was down to -8C, the ambient was 25C and the Peltier cold side was 10C.
The Engel cycled for 5 minutes on, 3 minutes off. Will be interesting to see if the cycle times alter with Peltier on & off.
In real life out prospecting I would probably set it 25C. ie: If the ambient temperature rises to 25C the Peltier will kick in. When the ambient drops to 23 the Peltier will shut down.
During our prospecting season once the sun drops for the night the ambient temperature drops rapidly so the Peltier would be shut down all night and not start up until the next afternoon or when it again reaches what ever temperature I set.
Maybe set up a catch can under the "cold side" about a dessert spoon of water collected in the bottom of the box. :lol:
If nothing else it has been an interesting project.

 

[ctxkid]

top job NJ !
these things a fun and very addictive

 

[ctxkid]

just a short one , try taking the fan off the heatsink , and place it away , i recon it will get colder