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Old 09-17-15, 12:28 PM   #71
marx290
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They were built to last, and I thought often about the fact that I was using a refrigerator that could have been bought by my grandparents when they were younger.

Those old units (one refrigerator repairman called them 'Old Girls'), the very first ones came out when electricity was new and expensive, so to attract buyers, the units had to be very economical. Later, when the electricity rates were falling and power companies main problem was selling more electricity, the units became much less efficient, like the 'round top' units.


But the Old Girls were in use before DuPont chemicals had the brainstorm to make a synthetic, patentable refrigerant. The Old Girls used an organic refrigerant, often sulfur dioxide. To my knowledge, there is no one left who is able to service a sulfur dioxide refrigerator.

The compressors in those things lasts a very long time. The part that most often goes out is the motor starter. Motor starters made for modern refrigerators are cheap and will work on the Old Girls. I was able to successfully keep my Old Girls going by replacing the motor starter, and I was able to get another 15 years from each one.

A yard ornament won't work out, but a garage ornament... now that is a whole other story!

If you really have a liking for the 'Old Girls', just keep your eye open, and they will come to you.

By far, my favorite Old Girl is the Monitor top. I had one proudly in my kitchen for many years, just like this one:


I mean, putting the compressor on the top, and letting the heat rise, away from the refrigerator... what a concept!

Best,

-AC
As I understand it, one of the properties which made sulfur dioxide such a good refrigerant, was that it acts as an excellent lubricant in the compressor and miscibility problems with the compressor oil (probably mineral oil) were non-existent.

These old girls were built at a time when the market was not yet saturated by refrigerators, so companies were building units to sell to first time buyers. Later, in the 50s and beyond, during the hyped up drive to sell to consumers (and not just citizens), manufacturers increased the dimensions of the refrigerators (and especially the freezers for all those TV dinners) to accommodate new tastes and more storage. Another way to increase size, was to reduce the insulation thickness, thus the inside dimensions got larger without increasing the footprint.

I suppose the larger freezer capacity and the energy intensive defrosting that goes with it doesn't help matters either.

Then there's the strip heaters they added to the door mating surfaces to prevent condensation, plus the heaters used in the cabinet walls for the same type of issues, associated with poor insulation.

I think there were a lot of reasons why refrigerator / freezers went through such a long period of inefficiency (arguably continuing to this day). Production of junk is the industry standard when that industry is based on profit and growth.

Regardless, I think people should have an affordable alternative. I would like to produce one.

You did a great job with this freezerator, AC_Hacker! I think it demonstrates how simply modifications can make a huge difference. I'm curious, have you ever attempted to measure the evaporator temperature to get an idea what the delta T is?

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Old 09-17-15, 04:42 PM   #72
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Less than 0.4KwH per day is real good.
By comparison my modern 2013 Kenmore (full size up right, freezer on top) uses about 1kwh per day.
Energy star my arse.
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Old 09-18-15, 09:28 AM   #73
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I'm curious, have you ever attempted to measure the evaporator temperature to get an idea what the delta T is?
The evaporator temperature is a moving target... do you mean peak-chill?

And what temp are you looking for to compare it to?

-AC
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Old 09-18-15, 09:38 AM   #74
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Less than 0.4KwH per day is real good.
By comparison my modern 2013 Kenmore (full size up right, freezer on top) uses about 1kwh per day.
Energy star my arse.
I'd say that the Freezerator hack has been a huge success.

I have mentioned this before, the Freezerator is in a perpetual defrost mode, and the inside is always damp. This turns out to be excellent for produce, because it never dries out. On the other hand, there is a drainage issue to contend with. My current configuration has not satisfactorily solved that issue... I sort of do a periodic mop of the interior. I noticed that top-loading freezers often have a drain hole in the bottom, which would b perfect for attaching a drain tube to. I've also seen mini freezers that have a self-defrost feature, which includes a drain tube.

-AC
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Old 09-18-15, 10:47 AM   #75
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I think where my curiosity peaks, is in trying to evaluate the performance of a cap tube system designed to operate at around 0 to 10 degrees F, which is never allowed to drop below freezing. So yes, I'm curious of what the lowest surface temperature the evaporator reaches, but I'd also be curious how much superheat is generated, or in other words, just how starved the evaporator is.

Don't get me wrong; I am impressed by how little energy a box of that size, with that little insulation, can use. I'm interested in doing a small refrigerator project from scratch sometime, and it is pretty apparent that the passive heat exchanger is the way to go (with moisture management).

Yours is the first freezerator I've seen which wasn't a chest type. I wonder though if they all share the characteristic of a starved evaporator. I would think the cap tube is too long, or too narrow. But then again, I don't have much experience there! I'm actually going outside in a few minutes to construct a tiny DC dehumidifier with one of those Chinese Coke can compressors! Going to try my hand with some cap tube.
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Old 09-19-15, 05:10 PM   #76
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Running a cap tube metered circuit is always a trade-off. With a shorter tube, the system capacity is increased. With a longer tube, the balance point dT is increased. A longer cap tube will take longer to reach a colder box temperature; a shorter cap tube will reach a less cold box temperature faster. So with this freezerator application, shortening the cap tube would give you a faster pulldown of cabinet temp and shorter run times of the compressor.

This all sounds great, right? The only downside is that you run the risk of flooding the evaporator.Once the dT maxes out, the evaporator saturates. The liquid refrigerant cannot all boil off, so a fraction passes through, due to an increase in suction pressure (vs. a longer cap tube) . If this liquid reaches the compressor, bad things happen.

Better to starve the evaporator than to flood it. All refrigeration compressors are classified by the back (suction) pressure they are designed to operate with. Most freezers use low back pressure compressors, which are designed to cool themselves without much mass flow of refrigerant. This is why they are relatively larger in size than their heat pump counterparts of equal capacity: the motor and compressor head have more iron to shed their heat through.

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Old 09-19-15, 10:56 PM   #77
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...shortening the cap tube would give you a faster pulldown of cabinet temp and shorter run times of the compressor...
I really don't see that pull down is an issue. I mean the Freezerator is actually a freezer, which has ample cooling power, but you are asking the compressor to run until a higher target temp is reached, the result is it runs in cycles of much shorter duration. If it is not able to meet the temperature, it just keeps running continuously until target temp is reached... then back to business as usual.

The effort in making this thing ultra-minimum. the cost of a unit is the cost of a very cheap freezer plus $20. The cost of running this thing is astonishingly low.

It's actually the simplest, most effective hack I have ever tried.

Before you wear yourself out try to improve it, you really ought to try it out... you'd be amazed.

If you actually want to improve on this thing, improve on dealing with or eliminating condensation. That actually is a problem.


-AC
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Old 09-20-15, 08:36 AM   #78
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Oh no, I am a fan of the keep it simple stupid approach as well. Operating a low-temp fridgie unit in medium-temp range is brilliant. With the decreased temp difference between ambient and icebox chamber, everything about the unit performs better than originally designed.

Also, with mass-produced designs, thousands of man-hours of design, trial, and testing work has already been invested. Many models have generations of preceding units' work to stand on. Reliability and longevity is not usually a problem.
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Old 10-06-15, 11:43 AM   #79
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The only bad thing I can think of that can happen with keeping food in a cool wet environment such as one of these conversions is listeria.
It likes cool wet environments.
It can double its numbers every 36 hours at 39'F.
So the closer to freezing you can keep your conversion the better.

Pathogenic listeria is normally only harm full to young children, old people and the unborn.
Cooking it kills it and I don't believe it leaves behind any harmful toxins.
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Old 10-06-15, 12:39 PM   #80
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The only bad thing I can think of that can happen with keeping food in a cool wet environment such as one of these conversions is listeria.
It likes cool wet environments.
It can double its numbers every 36 hours at 39'F.
So the closer to freezing you can keep your conversion the better.

Pathogenic listeria is normally only harm full to young children, old people and the unborn.
Cooking it kills it and I don't believe it leaves behind any harmful toxins.
Thanks for that, I wasn't aware.

The temperature does cycle, and runs in the 38F - 40F range.

-AC

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