Water cooled refrigerator coils
This may seem weird, but I’m curious…
We just bought acreage in west central Florida and we’re planning our home. We plan on making everything as energy efficient as we possibly can, and I ve been researching geothermal ground loop heat pumps.
As I’m grabbing some leftovers out of the fridge, I feel hot air being blown on my feet from the condenser coils underneath. At the same time I hear the AC kick on outside. The lightbulb flickers on above my head… I’m running the AC to cool the room that is being warmed by the fridge…
In one of our floor plan ideas we have the kitchen next to the garage/workshop where the mechanicals will be. The ground loop heat pump will be just 2 feet to the left of the fridge on the other side of the wall… would it be possible to build a Frankenstein water cooled refrigerator?
I could remove the condenser and coils and place them on the other side of the wall and have some of the water from the ground loop diverted to run around the condenser coils to more effectively cool them.
The fridge will be built-in, so it will not be moved once it is installed.
Are there systems like this already?
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There are systems out there to create a separate condenser, evaporator, particularly for the marine industry. But the complexity and cost can hardly be justified for a home refrigerator. Just get a high efficiency home unit and the heat loss is modest. If you really want to be extreme, and don't mind the limited capacity and high cost, then look at the Sunfrost line of refrigerators.
For one thing, you'd probably void the fridge warranty.
Maybe Martin uses a Sunfrost on his off-grid home? Or propane? Martin?
More than a decade ago FHB ran an article on someone who made built-in custom refrigerators with the condenser and coils located in a service room behind. I was intrigued enough to talk to the service guy who was installing the walk-in cooler at a restaurant I was renovating. He quoted me $1500 for the parts and labour, plus the cost of the refrigerator itself. That buys quite a bit of electricity.
James, Martin wrote a bit about his fridge a while ago. IIRC it's several decades old, tiny, and the compressor is on top, I don't remember much else. It was actually a pretty fascinating story with some history though.
Edit: here it is.
//m.etiketa4.com/blogs/dept/musings/choosing-energy-efficient-refrigerator
L.T., there are many choices of new refrigerators 18 to 21 CF size which use less than 400 KwHr per annum (measured using the Energy Star protocol) or around $50 of electricity p.a. at typical FPL type rates:https://www.psegliny.com/files.cfm/qualifying-me-fridge.pdfAn efficient 30+ SEER mini split should remove this amount of heat using fewer KwHrs, so the net possible savings is limited. It is possible to convert a chest freezer into a more efficient refrigerator, chest freezers have thicker insulation, if you don't mind the change of form factor nor the absence of a freezer compartment:https://www.builditsolar.com/Projects/Conservation/FreezerConversion/FreezerConversion.htm
Of course, it would not take many PV panels in a grid tied PV array to generate enough electricity to run both an efficient refrigerator and a mini split to remove the relevant interior heat load.
L.T.,
The answers so far make sense. It's technically possible, of course, to locate the compressor far from the refrigerator, as is done at most supermarkets. It's also possible to develop a water-cooled refrigerator -- although then you have a new problem (cooling the freezer).
The limits aren't technical -- they are financial. The potential energy savings are too low to justify the high cost of all of the required hardware.
After 25 or 26 years, my Sunfrost refrigerator (which originally cost me $1,700) finally conked out. The price of a new Sunfrost of the same size is up to $2,200. So I went to Home Depot and bought a $329 refrigerator (Magic Chef HVDR1040W) to replace the Sunfrost. The annual energy use in kWh is the same as the price in dollars:329 kWh per year.
It's hard to justify more expensive equipment with numbers like that.
Hi L.T.: according to htts//pvwatts.nrel.gov 500 watts of PV panels in a grid tied system near Tampa FL should generate 782 KwHrs per year, more than enough electricity to run both an efficient refrigerator/freezer and to run an efficient mini split to remove its applicable interior waste heat. At $3 to $4 per watt installed cost (for a medium sized system) less the 30% federal tax credit, 500 watts of PV panels at $2.10 to $2.80 net per watt should cost proportionately around roughly $1050-$1400. Of course, this assumes an unshaded building lot appropriate for a PV system.
Thanks for all the answers!
This is good info to know. I thought about a "refrigerator chest" back in my bachelor days. I knew it would be more efficient due to the cooled air not escaping, but mostly because I had 2 in the garage. I never got around to doing it though.
I've mentioned it to my wife and received the silent eye-roll.
Not a NO! So the possibility remains...
再次感谢所有的答案!我是苏re I'll be posting questions as we come across them.
LT.Son
LT,
If we were discussing this on Houz or some similar site, rather than GBA, I'd encourage you to pursue it. An almost silent built-in refrigerator would be a very nice thing to have.
I googled for a couple of hours looking for SOMEONE who mentioned or tried this before. Never saw a reference to it, so I started searching for forums or discussion boards that seemed to have people who knew what they were talking about... I found someone on another site refer someone here, so I took a look...
I gotta say, every topic I've looked through has people responding not just with, "Well I think this" and "My cousin's girlfriend's college roommate's uncle told her...", but with DATA. And not just one-and-done, but long-term measurements.
The folks here are pretty hard core!
Thanks again!
And I may try it anyway...
My father-in-law's got several working refrigerators... in his... shed... yeah, totally not sitting on his back porch under a blue tarp... not at all...
As others said, sailboats often use discrete systems with thick/vacuum insulation, water cooling and thermal storage (cold plates). It all works fine, but isn't likely to be cost effective for other uses.
L.T., the reason the compressor is running in your fridge is because the fridge absorbs heat from the room, warming its contents, so a large part of the heat you feel coming from under the fridge is heat that will be absorbed back into the fridge.
The net resulting heat into the kitchen will just be from the energy required to drive the compressor itself. If you used a coil from your ground loop to cool the compressor body you'd probably be close to having a fridge that added no heat to your kitchen.