Cabinet cooler needed

Jono06

Hi there,

I have two smaller wooden cabinets / wardrobes, reasonably (but not very well) insulated. Each cabinet has a thermostat with a simple relay switch as an output (can switch 240V up to 2.2kW). This can be used to turn the power to a cooling unit ON / OFF based on temperature.

My problem is sourcing the cooling unit. Currently I have a 150W Peltier cooler with a small fluid heat sink, which manages to bring the temperature down from 27 degrees by some 1.5 degrees, which is not enough, I need to achieve around 7 degrees difference.

Each of the cabinets have roughly 1 sq. meter in volume (with shelves) and will be filled with jars of honey, which have quite high heat capacity, so the cooling unit needs to be able to cope with it.

The unit needs to run on a standard single phase 240V / 50Hz mains power and be reasonably compact. Alternatively we have a 300W 12V power supply in case that can do anything.

Would anybody have anything to solve my problem affordably?

eeguy

Peltiers are generally awful and are incredibly inefficient.

What temperature do you need to maintain?
Does the cabinet need to be sealed?
Can you just use a fan to circulate air?

Jono06

Thanks eeguy,

Yes, Peltier solution is not good indeed. For 150W I would expect a better rodeo.
We need to be in the ballpark of 20 Celsius, which doesn't sound like we need too much power.
The cabinet is sealed only so it doesn't exchange heat with outside environment, however there is no other reason for it to be sealed.

A simple FAN solution would simply circulate 27 degrees air around without cooling it, so I don't think that's a solution unless I am missing something.

Do you have a potential solution in mind?

Calahonda52

Where is the 27 coming from?
can you relocate the storage area so as you can draw cold air from outside

brightspark

Wouldnt it be easier to purchase a wine cooler?

http://www.currys.ie/category/wine-cooling-mini-refrigeration/395.2.5

As you have found the peltiers to be unable for the load involved and I doubt if gas refrigeration is really feasible for DIY.

Gas fridges usually have mechanical valves so the temperature regulation is at the operator discretion not atmospheric conditions or internal temperature, aboot 8 times the power consumption of a compressor version too.
Most of the wine coolers, beer coolers and 12v chillers are Peltier based too but better insulated.

Why not use a regular mini-fridge?

Jono06

Jono06 wrote: »

A simple FAN solution would simply circulate 27 degrees air around without cooling it, so I don't think that's a solution unless I am missing something.

The fan on a peltier heat pump is to extract heat from the heatshink of the peltier (it should be ducted without restricting air flow rate and blow away from the heatsink..I think instinct usually has us force air onto the hot thing.

Although if you are using circulating water cooling I can't see forced air being much better...water is a far superior thermal conductor.