refrigerator thermodynamics

**mek42** · 07-09-2010, 09:50 PM

Someone mentioned that a full fridge was cheaper to run than an empty one and further suggested to put used bottles refilled with water in. My first thought was that water has a higher heat capacity than air, so after opening the fridge, less work would be needed to cool the warm air that came in when the door was opened. On further reflection, though, I don't think this is the right thing. A full fridge will have less displacable volume of free air, thus less warm air to cool after opening than an empty fridge. If this is the case, would just filling the space with closed, empty containers do the trick without filling them with water?

Am I thinking about this correctly?

**alotofgooddeals** · 07-09-2010, 09:56 PM

just reading that.....i was the one who stated that cause that is what i was told however your statement made me start to think....however i don't know if what your saying is true or not..

Originally Posted by mek42

Someone mentioned that a full fridge was cheaper to run than an empty one and further suggested to put used bottles refilled with water in. My first thought was that water has a higher heat capacity than air, so after opening the fridge, less work would be needed to cool the warm air that came in when the door was opened. On further reflection, though, I don't think this is the right thing. A full fridge will have less displacable volume of free air, thus less warm air to cool after opening than an empty fridge. If this is the case, would just filling the space with closed, empty containers do the trick without filling them with water?

Am I thinking about this correctly?

**frugalwarrior2** · 07-09-2010, 10:02 PM

I have NO idea. But I will impart a few words of wisdom from my childhood via my dad (think MI archie Bunker)

1. Get out your head out of the freezer it ain't an air conditioner.
2. Close the door,there's nothing any better in there then when you looked 5 minutes ago.
3. Regarding the fridge-Think about what you want before you open the door. Get in, get out , and be done w/ it.

So in modern day terms. Buy an efficient energy star model,make sure the seals are tight and the coils vaccumned. Avoid opening it often and for too long.lol.
I sure do enjoy frozen water bottles on these hot days and it is helping w/ the old diet too !!

**Ceashels** · 07-10-2010, 10:10 AM

I just mentioned this to my friend yesterday. He was thinking of replacing his fridge or his dishwasher (neither are terribly efficient and came with his home). He has little in his freezer but mentioned that it seems to run the motor a lot. I suggested he fill containers with water so they will help cool the air again after the door is shut.

I think water filled containers would work better than air because of its ability to hold its temperature longer. (It can also be used in an emergency if the local water main breaks.)