WonderFridge
 

Hi, during last september I've modded my refrigerator with aluminium-styrofoam foil. I've attached the foil between compressor and freezer part. I also added the foil between refrigerator and back coils.
Refrigerator is whirlpool, cca 12 cu ft (220 liters refrigerator and 110 liters freezer). It's rated for 0.9 kWh/day.
Before mod it used 0.9 kWh/day in the summer and 0.45 kWh/d in the winter (both are averages during one week).
After mod it's under 0.4 kWh/day in winter (lowest was 0.35 when wife was away for week :-)) and 0.6 kWh/day in summer (highest 0.75 kWh/day).

I recommend this mod to everyone.

http://ecorenovator.org/forum/attach...e-cam00166-jpg

Wow, impressive reduction in energy usage there.

How thick was the foam insulation you used?

More pictures would be great if you have them.

Foam is 3 mm (1/8th of inch) thick. It's the cheapest one I could get. Mod cost around $4 and already (in 319 days) saved nearly $8.

Average consumption is 514Wh/d, before mod I have no complete numbers, just the two values (summer + winter). If I average them, it's 670Wh/d. So savings are around 23%. Although this year has a bit colder summer, so that must be taken in account.

This morning (there's already 7 AM :-) ) I've realised that compressor isn't room temperature before starting a new cycle. So that's something to work on.

Picture is a bit blurry, I don't have proper camera, just ****ty phone :-)
The plastic container is for condensated water drained from refrigerator. As you can see I've made few small mods, but I don't know if they have any impact, or even if they don't harm the consumption. I just hated that cold and hot pipes were so close together and uninsulated.

http://ecorenovator.org/forum/attach...e-cam00170-jpg

A warm compressor actually is a good thing. This ensures there is no condensed refrigerant in the compressor. The amount of heat stored in the shell is not huge. Having a warm compressor on start-up actually helps the condenser hx start doing its job earlier, shortening capacity ramp-up from equilibrium.

The best easy thing you can do after insulating the box is to insulate the suction line. I use armaflex closed cell foam pipe wrap. The heat not gained by the exposed piping helps the compressor run cooler by reducing superheat.

I'm not completely sure, but I guess compressor isn't warm during winter (we usually don't heat much, so there's like 21°C (70°F). Also my refrigerant is R600a, which has boiling point -11.7°C, which to me loks pretty warm, since freezer should be cooled to -18°C. That means suction line can still contain liquid refrigerant, am I right?

I am no expert in refrigeration, so I don't know if my assumptions are correct.

Also I thought that condensator is doing best job when it's end is room temperature (which in my case it's not during cycle, only at the beggining).

r600a is a little lower pressure than r-134a on the pt curve. When the freezer is freezing, there is actually less than atmospheric pressure in the evaporator and suction side of the circuit. As box temperature falls, so does evaporator pressure. At design minimum freezer box temperature, the evaporator may be operating with half a bar of vacuum.

The condenser side of the circuit follows room temperature. At normal room temperatures, the high-side pressure is usually in the 2 to 3 bar range during operation. This relatively low pressure is the reason most refrigerators last many decades before they develop a refrigerant leak. Even a badly fatigued or corroded run of tubing will hold this amount of pressure until it literally crumbles apart.

The condenser has one main purpose: move heat to ambient air. As long as it is warmer than room temperature and airflow is not obstructed, it is doing its best. Even if airflow is somewhat blocked, it still does a good job, as manufacturers routinely oversize this hx.

Trying to improve condenser performance is challenging with refrigerators. Due to the low compression ratio the compressor works against (2 to 3 bar), lowering condensation temperature doesn't have much energy saving effect. On large, commercial walk-in freezers, the most common upgrade is a txv, which matches up evaporator temperature and flow rate of the compressor to save energy. On residential iceboxes, the txv is considered an unnecessary extra moving part that can fail.

So will anyone else try this? I'd like to know if my results are repeatable :thumbup:

JimiQ I like your thinking , my fridge has been insulated since 2012 , 4 years of savings and going strong.

With this 2007 Kenmore fridge the daily kWh average is .938 kWh a day , savings can certainly be had , a picture is worth a thousand words

http://ecorenovator.org/forum/attach...ion-fridge-jpg

http://ecorenovator.org/forum/attach...on-fridge4-jpg

http://ecorenovator.org/forum/attach...on-fridge5-jpg

http://ecorenovator.org/forum/attach...e-vent-001-jpg

http://ecorenovator.org/forum/attach...e-vent-007-jpg

In fact I've read your thread few months ago and you've been one of my inspirations for my mod. So thank you for that!

Unfortunately due to my laziness and space constraints I couldn't afford outside insulation

The majority of the savings will be saved from the insulation on the bottom of the fridge , it gets way to warm down there to not be insulated. A design flaw really.

You two have different types of condenser heat exchangers. The OP has a low density, flat hx that uses natural convective forces to release heat. These condensers are hard to improve upon.

Ecomodded has a high density, "pipe sandwich" exchanger in his fridge. These use forced air (via a small, quiet fan) to move the heat away. This is the type of unit I use to make really efficient space heaters or dehumidifiers out of. I also use the condensing unit assemblies as refrigerant reclaimers and vacuum pumps. The lineset that runs to the evaporator in the box is long and flexible enough to run out a window or through a small hole, and conveniently comes with its own fan as well. Not as efficient as the low density types, but easier to hack.

If you realy want a low consumption of electricity, do as I did: I converted a freezer to a refrigerator. Only by installing another thermostat.
The freezer has much more insulation than a regular refrigerator. On all sides that is, not just at the back or close to the compressor.
Now the yearly electricity consumption of this 250 liter "refrigerator" is about 50 kWh..

Yeah, but that wouldn't be approved by wife, and I also need freezer that's freezing (for leftovers, or meat, frozen pizza...) :-)
Also, I've read there are some problems with condensation inside converted freezer, aren't there?

You're right. Condensation is an issue.
But since the freezer was a type with drawers and the evaporator consists of different plates (one above each drawer) and the evaporating cooling fluid enters in the highest plate, most condensation takes place in the top. So just above the top drawer.
We regulary empty the water from top drawer. And when this is done on a regular basis, not much condensation takes place on the lower evaporator plates.
We use the top drawer for bottles only. And it's not a problem if they get a little wet.
I have plans, to connect a hose to the top drawer and bring it to the outside, so that condensation water will be removed.
But as with so many plans, they take time of which I have not so much available...
Maybe in the future......
By the way, we also have a auto-defrost freezer, where the condensation was originally led to the top of the compressor (to be evaporated again, but than outside of the freezer).
I changed it a little so that the water is collected in a bottle and we use it for an ironing station nowadays.
We don't need to buy demineralised water anymore....

oh, so it's not a chest freezer convert, now I get it. I didn't see any of regular cabinet freezers converted.

Yeah, I have the same drain - from refrigerator to container on top of compressor. (But we don't iron - ever, so I couldn't use the water)

You might be interested in looking at this:

AC_Hacker's Hasty Freezer Conversion Reduces Energy Use By 61%

Best,

-AC_Hacker

There's a populated island near my area called Lasqueti island that is without conventional electricity. Everyone uses Sun or Wind and Water as a micro power plant.


And everyone uses a converted chest freezer as a fridge as the doors position and the increased insulation factor work together.

So final numbers are 197kWh per 365 days, or around 540Wh/d. A bit higher than I expected, but still very nice.

Not bad at all. That is still roughly half or less than a normal fridge. I'm pretty sure I'm at 1.1 to 1.3 kwh per day.

I did more or less the same (foiled insulation between the back wall of the fridge and the hx coils, all the way down to insulate from the compressor's heat), and additionally moved the coils farther away (by 2-4cm), improving ventilation. This was 5 years ago and still going strong, the only issue I once had was condensation between the fridge wall and the insulation.

One of the downsides of the bottom-freezer design - the temperature difference between the compressor and freezer is greater than if the freezer was at the top.

I don't really know where to put this and I didn't want to start a new thread, so there it goes.

I stumbled upon an article about cooling fridge compressor by condensation drip from freezer coils.

https://www.sciencedirect.com/scienc...14157X17300813

I thought it would interest someone. They managed to loweer the consumption by nearly 10%

That is interesting it has me thinking could increase the gains by using a heat sink fitted compressor shell so it never gets hot in the first place increasing the cooling efficiency.

Ideally the hot air should be vented away from the fridge straight from the compressor and condenser

I once thought about using a small fan to blow air over the coils and/or compressor, but I guess the improved efficiency would hardly outweigh the fan's power consumption.

If you'd be able to start/stop the fan in sync with compressor running, it wouldn't consume as much as running nonstop. Also, depends on the fan :)

I had laptop cooling pad blowing air on coils, but it got dirty from dust and cat hair (stupid animals :D ). The consumption of whole system basically didn't change (the cooling pad ran of USB-outlet - like phone charger)

AFAIK virtually all modern (American) frost-free fridges/freezers dump the condensate to a drip pan with some condenser piping in said pan. this serves to mange condensate without a pump/drain, and also boosts the efficiency of the system (notwithstanding poorly managed evaporator defrost strategies).

but is said drip pan thermally connected to compressor/coils? Because mine was plastic with only 1cm squared direct connection to compressor, otherwise there was like 2mm air gap. So I removed the pan completely - even if something drips, it won't touch electric wiring, and I put different collector under the fridge, so nothing spill on the floor

for example:
https://s3-media2.fl.yelpcdn.com/bph...ZMn-VQ5Q/o.jpg

i've also seen it where the tubing "U"s down into the drip pan area. i don't think they used to do it for added efficiency, i think it purely for condensate management.

I finally got around to tuning my fridge a bit more:
1) I have installed two old PC fans (free, I haven't used them anymore) connected to molex-PC fan reduction ($1-$2) connected to USB-molex reduction ($0,6), connected to outlet-USB adapter (free with old cell phone)
2) installed insulated box around outlet of evaporator from freezer and inlet of evaporator (before expansion valve). It should work as subcooling heat exchanger (albeit the heat is exchanged by air, so not a big deal)
First measure lowered consumption from 0,7kWh/day (fridge is 8 years old, long are gone times when it consumed around 0,54kWh/day) to 0,53kWh/day
Second measure is on edge of rounding error of 0,03kWh/day (to just barely under 0,5kWh/day) so it's probably not working as intended. Unfortunately there is no way to connect the two pipes that I'm trying to cool/heat by each other

Nice reduction!

Would you have any pictures?

Sure, but it’s ugly as hell :D
http://i68.tinypic.com/judbua.jpg
http://i63.tinypic.com/jrwk8n.jpg
I’m sorry if the pics are too large