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Old 10-28-2008, 11:12 PM   #1 (permalink)
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Mass quantities of food in the fridge...

I'm sure you have all read that an empty fridge runs efficient because there is nothing that it needs to cool.

Also, a full fridge runs efficient because the cold food holds the temperature.

Well... we have started shopping at one of those discount warehouse stores. That means we have a ton of water bottles, juice cans, etc.

In theory, wouldn't it be the most efficient to load a few items at a time, so the fridge doesn't need to work too hard? And then try to fit all of the food in the fridge so it holds the cold temperature easier and again, the fridge doesn't need to work too hard?

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Old 10-29-2008, 01:33 AM   #2 (permalink)
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You could just throw some bottles of water in there when you empty it out to balance things out.
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Old 10-29-2008, 01:34 AM   #3 (permalink)
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Some properties of Thermodynamics apply...

As I understand it, when you place the room-temperature items in the fridge, the resultant temperature difference places a demand on the system due to the ambient temp drop, which = more energy consumed. Then once up to temperature, the demand is flat.

The biggest loss that should be inspected is, "how often is the door opened"? You lose a tremendous amount of cool air each time you open that door -- some people leave it open until the cereal is covered in milk! ...than back it goes.

Also consider the minimum temp settings.

All user-specific.

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Old 10-29-2008, 09:17 AM   #4 (permalink)
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Both of the above posts have very good points. Put empty milk jugs full of water in there as you get room.

I've never heard that fridges run more efficiently b/c they have nothing to cool. Also what your talking about isn't necessarily efficiency of the fridge but cumulative demand (e.g. we're not talking about the mileage but rather the total distance driven). If the fridge were perfectly insulated and sealed, it would run only once each time you open the door to recover from the air changes. Because of physics in our macroscopic world this is impossible, and your refrigerator gains heat through conduction and infiltration. The idea is that convection (to items in fridge) and conduction (internal to each item) is a slower process than the air changes in your fridge. This allows for the significant energy rise to be absorbed my as much mass as possible (also reducing the total volume of air which can be exchanged) which results in only maybe ~1 or 2 degree temperature change as opposed to if your fridge was empty the temperature change would be much more significant.

This is why I like having my bottom freezer fridge with 2 half doors. I can open just the door that has pop behind it minimizing the air change in the space, as opposed to opening the full size door nearly all the way to get something that's near the hinge.
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Old 10-29-2008, 09:29 AM   #5 (permalink)
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An empty frige uses the least energy only because there is no need to plug it in. An almost full fridge is the most efficient state. The mass of cold solids and liquids hold heat better than air alone.

If you go with the water jug idea, fill the jugs with the water from the shower the next time you are waiting for the water to warm up. In summer, when jugs are unused, keep them in the basement or other cool place. In the winter perhaps an enclosed porch.
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Old 10-29-2008, 10:23 AM   #6 (permalink)
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putting warm jugs of water into your fridge is a terrible idea. Instead of cooling 1L of air, you now have to cool 1L of water, then when you need the space, you take that 1L of cold out and it warms up beside the fridge.

Just use it like normal, keep the temp as warm as you can and don't leave the door open. If its old, get it the heck out and put a good one in. If the seals are broken, replace them or replace the fridge.
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Old 10-29-2008, 10:23 AM   #7 (permalink)
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Quote:
Originally Posted by Sean T. View Post
In theory, wouldn't it be the most efficient to load a few items at a time, so the fridge doesn't need to work too hard? And then try to fit all of the food in the fridge so it holds the cold temperature easier and again, the fridge doesn't need to work too hard?
Nope, load it all at the same time....

1. That food needs X amount of energy to cool down. Slowly adding does not change the number "X" - when you use that energy doesn't matter, you're still going to use it.
2. Your refrigerator is basically a small air conditioner - the refrigerant system operates at/near peak efficiency while in "steady state" conditions. That is, the least efficient operating time is during start up while the compressor attempts to pressurize the high side. During this time you have the lowest Coefficient of Performance (heat moved/work in) - so you're doing a lot of work, and not cooling very much. Once the high side pressure has stabilized, you've reached steady state.



On the subject of refrigerators.... I'd love it if modular systems were mass produced for home use. I'd want a permanent liquid coolant chiller with an exterior condenser - then, just hook up some hoses to your refrigerator and you're good to go I hate that I have to move heat from my refrigerator to my kitchen, then from my kitchen to outside (VIA central a/c). Then, replacing the appliance should be cheaper (aside from initial investment).
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Old 10-29-2008, 10:27 AM   #8 (permalink)
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That is the perfect system. But why throw the heat outside? Put it into your hot water tank! Pre-heat your oven with it! Then when your oven is turned off, speed-cool it with the same liquid to heat up your water heater more! In the winter, warm the house.

When i make my millions, i'll have a wonderfully efficient house built.
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Old 10-29-2008, 11:02 AM   #9 (permalink)
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Quote:
Originally Posted by MazdaMatt View Post
That is the perfect system. But why throw the heat outside? Put it into your hot water tank! Pre-heat your oven with it! Then when your oven is turned off, speed-cool it with the same liquid to heat up your water heater more! In the winter, warm the house.

When i make my millions, i'll have a wonderfully efficient house built.
My utility used to give rebates for having a heat recovery system on your a/c
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Old 07-31-2012, 05:30 PM   #10 (permalink)
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Another point is that you should be aware of what is in the fridge and what will be rott away soon. And there for your fridge should not be too full.

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