Improving Refrigerator Efficiency: A Thought

Yes that would work, but it is tricky.

You can do pretty well with just a chest freezer and a temperature controller. See: Chest fridge for example which runs on 0.1 kWh per day.

 

Someplace a few years ago I saw some pretty through analysis of that scheme. If you are in an AC cooled house, the savings are even better because a regular fridge dumps heat into the cooled house and you have to pay to have the house AC remove the heat.

If the fridge had a large mass of the right PCM inside it, you could most likely eliminate any daytime running.

However, if you take look at the simple solution like Corwyn mentioned in the post above mine, it makes the complex more thermally efficient solutions not worth chasing except for the fun of it.

Many years ago a friend that lived on his sail boat built his own chest type fridge with 2 or 3 inches of high quality foam insulation and it ran on practically nothing.

 

Ergonomics: top-load washer, stand-up freezer, stand-up fridge. (Stand-up fridges with small freezer compartments have them on the top. Larger freezer compartments are on the bottom).
Energy/resource Efficiency: front-load washer, chest freezer, chest fridge.
Space efficiency: front-load washer, stand-up freezer, stand-up fridge.

It's pretty easy to see why usage patterns are as they are in different places.

Well, one problem I can see is that you're pre-cooling the fridge. It's a bit like going from cruise control to DWL in an automatic, which relies heavily on prediction to handle the variation efficiently.

 

Should be Energy/resouce efficiency: Horizontal axis washer. Staber makes a top load, horizontal axis washer. It works very well.

 

I was talking with a heating equipment rep the other day, and he was singing the praises of outdoor temperature sensors. I asked him why he didn't just hook up the equipment to the internet and get a 2 day weather forecast, and he looked at me as if I had invented e=mc^2. Seemed pretty obvious to me.

 

seems to me an out door vent that would let you pul in cold air and exhaust warm air that could adjust seasonally would be a fairly efficient option.

 

The first part is easy. Set the fridge as cold as possible, and put it on a timer. You'll need a good thermometer, and maybe a flashlight, to keep an eye on things during the day. The problem I see with the pulse and coast idea you are working with is for food quality. There spots in our fridge where things might freeze. P&Cing would make it more likely to happen. While freezing and thawing of food in a fridge won't spoil it, it could have negative affects on taste and texture. Ever freeze cream cheese? Once thawed, it still has a crumbly texture from the freezing.

Actually using outside air would entail moving the condenser coils to the outside, like a central air conditioner. No reason why it couldn't work. I remember a site for heat pump water heaters that did that with the other side of the coils so they could be placed on the roof. It just increases cost of the unit, and likely means professional installation. People want to change kitchens too often for that, or we could just tie the fridge into the AC or heat pump of the home.

If you were willing to have part of the fridge on the outside, one of the real high efficiency, off the grid, fridge brands offered solar power that, I guess, worked like a propane fridge.

Some of the vertical ones have caught up. Health issues and room layout meant a front load wouldn't work for us. I knew there were top load horizontal models. They just aren't on the floor in most stores.

Aside: my coworker was just wondering how the D got into fridge and why we don't write frig this week.
And it appaers frig is perfectability acceptable spelling, unlike that perfect mess I tried there.

 

don't frig with the spelling.

 

Refrigeration systems are typically designed to 18-20 hours per day to meet expected load requirements. Most of the load in a home refrigerator is from opening the door. The cold air spills out...which is why a chest system is more efficient, and why the compressor doesn't turn on as much at night. Putting the condensing unit outside would increase the cost far beyond any possible savings, and might not result in any electrical savings at all. Running a refrigerator at it's coldest setting will probably ice up the coil, as the system is designed to defrost during the off cycles. Keeping the condenser coils clean is the best way to minimize electrical usage.

 

....I like this chest idea too. Can you buy one with this kind of efficiency?
Hybrid approach could be to have one of these in garage or basement and smaller unit in kitchen.

 

Yes, but now you have a hole in your heating envelope (read: insulation), and a duct and the space surrounding your fridge containing cold outside air in your living space. So insulate all that you say? By the time you are done you will have done basically the same thing as moving the coils outside.

 

Probably. Coils might be on the back.

Can you draw a picture of what you want? Label everything with its temperature and insulation value, and you (or we) can figure out where heat is going, and how much. All those new surfaces are opportunities for heat loss, and water infiltration and other unpleasant things.

 

Unfortunately, a btu is a btu. If you "store up" btu's, you still have to buy them first, and it still takes the same amount to cool the box. Even putting the condensing unit outside would only help during cold weather. In the summer, you would pay it all back with higher head pressures. Water cooling the compressor is the most efficient way to keep electrical costs down if the water cost doesn't offset the savings.

 

Do commercial refrigeration installations do this? If so, or if not, you have some guidance. If this does not appear worthwhile for (e.g.) 2000 cubic feet, it is unlikely to be useful for 20 cubic feet. And to the contrary, whatever (e.g.) grocery stores do, that's likely to be the best one can do, all things considered.