How to convert a fridge into dehumifier?

[julee]

I saw a fridge block diagram and has all the components that needed in a dehumidifier. Question is it possible to transform my fridge into dehumidifier?..I think i need to add only a condenser to to extract the water.
What about that...eh?

 

[Cliff_J]

A refridgerator is a compressed liquid heat pump like an air conditioning unit - it will have an expansion orfice and 'evaporator' heat exchanger that will obviously cool the air and extract moisture from it as the liquid transforms to a gas. But it will also have a pump increase the pressure of the gas and a 'condenser' heat exchanger to allow the refridgerant solution to dump its heat before repeating the cycle. On some fridges this is a very large coil that covers the entire back of the unit, on others its located on the bottom with a fan to move air past it.

If you could move air past the evaporator coil it would tranfer its heat to the refridgerant and in the process have reduced humidity, and then if you moved it past the condenser the heat would be transferred from the coil to the airstream. Thus the air would exit slightly warmer and with less overall humidity (and even less relative humidity). So yes you could, but how well would the supplied heat exchanger coils work?

 

[russ_watters]

Much, much simpler: open the door (kinda implied by your second paragraph).

The only difference between an air conditioner, de-humidiffier, and a refrigerator is the location of the coils. An air conditioner and a refrigerator are actually identical: in both cases, the condenser (warm) coil is outside the system being cooled and the cooling coil is inside the system being cooled. With a humidifier, both coils are inside the space (and with a heat pump, the warm coil is inside and the cool one is outside).

So if you open the door, that removes the boundary between the space being cooled and the environment (in this case, another space: your house). I wouldn't recommend this though - your refrigerator is not designed for constant operation.

 

[julee]

Thanks to Cliff_J and Russ_Water for your valuable contribution. And how about passing a hose thrugh the ice maker with hot air...? What is the machine eficience in this case..? Mr. Ju Lee

 

[Cliff_J]

If you were to pass the hot air in a tube through the ice maker section, without any of the air interacting with the existing air inside the ice maker, it would range from moisture being collected on the inside of the tube (low speed, low heat) to having the tube warm the inside of the ice maker section up to its capacity to remove that heat (high speed, high heat).

Ever hear of how air conditioners for a house are rated? Like a 3 ton or 4 ton for a whole house and a 1 ton for the basement? That means the unit can pump enough heat in 24 hours to equal 1 ton of ice. Its not actually design to work at a temperature to make that much ice, but the idea is how much heat it can move and that's 12,000 BTU/hr.

And in your scenario, its how much heat capacity you have to work with.

As long as the hose/tube/box the air is passing through stays below the dew point temperature of the air passing through it then it will condense some moisture out of that air. Once you pass enough hot air past it and exceed the heat capacity (and in turn raise the temp of the hose above dew point) then its effectiveness will be very low. As far as efficiency, I'd guess quite poor but Russ would know much better than I would.