Alaskaflyer
Guru
LOL. Or you could drive this and get 35 feet per gallon at 1 mphView attachment 123148
Amazingly efficient in my opinion, considering the weight. Crazy how much energy is contained in a gallon of refined petroleum.
LOL. Or you could drive this and get 35 feet per gallon at 1 mphView attachment 123148
Well, the claim is that a particular brand of drawer fridge is 3X more efficient than a household fridge. This would be fantastic news, amazing in fact. Like saying you can drive a Volvo earth mover to Chicago on 200 gallons instead of 600 that the CAT uses.
At some point you run out of either energy input (in my case solar) or storage capacity (batteries) and a fridge using so much less power would be worth the money in that case even to someone cheap like me. Energy saved is energy you don't have to produce and store.
Theoretically it could be easily accounted for by noting that it "runs" less over a set time period to provide the same cooling factor. How it would accomplish that I don't know but could easily be explained by better insulation and heat dissipation? What am I missing? If you have 100 gallons of water to be pumped, if the 3 GPM pump uses more energy while running compared to the 1 GPM pump but accomplishes the task in 1/3 of the time and then shuts down to standby, it's pretty much a wash in power usage.
Sbman, to clarify, I merely observed the manufacturers' specs of two like kind fridges, in this case, a domestic Summit 4.2 c.f. single door fridge compared to a Vitrifrigo 4.2 c.f. single door fridge. To be precise, I said that the specs show that the domestic fridge draws three times the number of watts when the fridge is running according to the manufacturer of each fridge. I did not make these numbers up. I got them from the spec sheets.
Sbman, to clarify, I merely observed the manufacturers' specs of two like kind fridges, in this case, a domestic Summit 4.2 c.f. single door fridge compared to a Vitrifrigo 4.2 c.f. single door fridge. To be precise, I said that the specs show that the domestic fridge draws three times the number of watts when the fridge is running according to the manufacturer of each fridge. I did not make these numbers up. I got them from the spec sheets. Analogizing, what I am trying to understand is how an engine that uses three times as much fuel when running is not meaningful.
Or, how about a water pump. A pump that, when running, pumps 3 GPM is very likely to pump three times more water than a pump that pumps 1 GPM. And, big surprise, how much water is pumped is wholly dependent on how long the pumps run.
My test numbers, as it turns out, I do not need to do a test. I happen to have a Balmar SG-200 battery monitor which shows precisely the number of amps being drawn from the batteries. I can report with certainty that the draw is 3.4 amps/ 41 watts. I will leave it to you guys to do the comparison. I am really curious, very curious what you conclude. From casual observation I estimate the duty cycle to be no more than 50%.https://www.vitrifrigo.com/us/us/drw180a-all-in-one-single-compartment_2
The numbers Vitifrigo post are well within reason for their little drawer fridge. It's a bit more efficient overall than my household fridge. The numbers they post for it in freezer mode are terrible. They state 1.1 kWh/24h (12/24Vdc) for a small 2.8 cu/ft freezer. That's more power than my entire 9.9 fridge uses with a freezer about the same size attached.
Your test/measurement would be very interesting. 24 hours would be better, but 8 will tell some of the story. I am not skeptical of the numbers Vitifrigo posts, they sound correct. I'm not skeptical of energy star numbers either, I've measured enough fridges to know their testing is pretty accurate. I'm skeptical that any fridge is 3X more efficient than any other.
The Ah consumption is from my battery monitor, yes. Remember that Ah is a unit of Amps/Hour, but that is not power/hour because voltage is not included. Power is volts * amps = watts. Energy consumption is measured in Watts/hr = Wh. Your battery monitor integrates the data with samples taken multiple times per second which is helpful because neither voltage or current is stable, they vary. Integrating Volts*amps gives you the real picture.
If we were measuring your diesel engine and trying to compare our boats MPG, we would not take your idling fuel consumption, multiply it by the hours required to go a distance and then claim that's the boats MPG. Nor would we put it in gear against the anchor and, note it's fuel consumption and multiply that by a few hours to find the MPG. We'd motor up and down a measured course in both directions (to cancel out wind and current variations) a few times and make notes of the consumption to do so, divide by our fixed course distances, then we could compare notes on our MPGs. That would account for the entire system, hull design, propeller losses, engine design, weight, transmission losses, etc...
My magic chef is 4.2 Wh per cu/ft at 75 degrees. The viti 2.8 drawer fridge is 2.8 Wh per cu/ft at 77 degrees, somewhat more efficient.I do understand what you are saying and it's absolutely correct. The problem is that doesn't show the picture of the fridge, only the compressor. If you set those two compressors next to each other, one draws 3x more power than the other, absolutely. But, it's the system that is of interest as a whole, none of us have compressors sitting around running all the time, they are built into fridges, just like none of us have diesel engines sitting alone running, they are in boats to do work. Well most of us at least, I might have a lone diesel engine here or there from time to time.
Put each compressor in the same exact fridge, and assuming each has the overall cooling capacity to cool the box and are set to maintain the same temps they will average about the same power draw over time. The 3X one will run a lot less and the 1X will run a lot more, but the energy used to cool the box will be very similar, if they are of the same design it will be VERY close.
To evaluate a one fridge over another for off-grid use you need to know how much power it draws compared to others in similar conditions over a fixed period of time and divide that by the capacity of the fridge so you know how efficient it is at cooling each unit of capacity. You can compare a 1.2 cu/ft to a 14 cu/ft that way. You can compare a peltier to a compressor fridge that way, or even an absorption fridge running on electric.
My magic chef is 4.2 Wh per cu/ft at 75 degrees. The viti 2.8 drawer fridge is 2.8 Wh per cu/ft at 77 degrees, somewhat more efficient.
Given that, the household fridge is 1/3 freezer. I get 6.6 cu/ft fridge and 3.3 cu/ft freezer, so it's not a fair comparison giving the viti a significant advantage because it doesn't include a freezer area.
Freezing is much more energy intensive than refrigerating. To run two vitis, one as a 2.8 cu/ft fridge, and one as a 2.8 cu/ft freezer(5.6 cu/ft total) would require 1250 Wh /24 hours at 77 degrees per there specs, so it's 9.3 Wh/cu/ft/hr for the two, half as efficient as the household and still has less storage capacity in all respects.
My conclusion from this evaluation is that if you want a small fridge only, the viti 2.8 drawer would be a nice efficient choice in a convenient package that could fit in many situations others just wouldn't. It is also a stylish, modern looking appliance. It is not a good choice as a freezer, it does not have sufficient insulation to work efficiently at freezing temperatures and that is evidenced by it's high consumption when in freezer mode.
Keep in mind, the Vitrifrigo and other Danfoss compressor units are as good as it gets for purpose built marine units right now. Home units vary far more in power consumption (and suitability for install into an enclosure, like on a boat). So while some will be dramatically less efficient than the marine fridges, others won't be.
To get a true answer to which solution comes out on top, we'd have to figure out what the most efficient fridges available of each type are in a given size range, then account for which designs can accept added insulation and which can't. And then assess efficiency from there.
The test, here are the results. Ten hours overnight with a 20% addition for the fact that the main cabin is cooler overnight. Extrapolated to 24 hours, my two 4.2 cf Vitros consumed 110 amp-hours or 1.3 kilowatts. Certainly not precise but probably pretty damn close.
While I'm not a fan of ABYC, this seems like a place where they could be consumer beneficial. If they required that boats meeting ABYC standards had to use appliances with Energy Guide decals, manufacturers would immediately test their appliances to the federal standard.
If you were building a new boat, wouldn't you want to have an idea of power consumption (energy efficiency) when picking refrigerators, water heaters, air conditioners, furnaces, engines, generators, and most other energy consuming components.
Ted
Keep in mind, the Vitrifrigo and other Danfoss compressor units are as good as it gets for purpose built marine units right now. Home units vary far more in power consumption (and suitability for install into an enclosure, like on a boat). So while some will be dramatically less efficient than the marine fridges, others won't be.
To get a true answer to which solution comes out on top, we'd have to figure out what the most efficient fridges available of each type are in a given size range, then account for which designs can accept added insulation and which can't. And then assess efficiency from there.
Both of my units are refrigerator only, no freezer sections. We have a 5-cubic foot chest freezer on the flybridge.That's some great information. So 2x4.2 units to get 8.4 cf using 1300 watts in 24 hours. You have one set to fridge and one set to freezer? Less efficient than my 9.9 at 1000W per 24 hours, but still within a good range and I'm sure they are a good fit in your cabin. Mine is strapped down so it doesn't walk around!
Your point about the 2.4 viti drawer is well understood. Given it's lack of features (no freezer) it is quite a bit more efficient than my larger combo household unit at doing a somewhat different job of fridge only. I do think it would make a good off-grid fridge solution for those that want a convenient drawer style fridge.
Also your point about the warm sides is a good thing for people to keep in mind, not all household fridges do this, but most are moving this way. They used to have an electric heating element inside the metal casing to prevent condensation, but this drew a lot of extra power. The new trend is to wrap some condenser lines around the inside of the casing and use their heat to keep the condensation down. This may be a bad thing if you have a tight space to fit a fridge into.
The overall conclusion here is that there is no magic bullet for refrigeration, there are differences and you can spend a little money or a lot of money and get similar results, if you are careful and want to do some research you can pick the best solution for your requirements from what's available. Or you can just buy something and let it do it's thing and not worry about it.
Crazy how much energy is contained in a gallon of refined petroleum.
Tha'ts why a custom built reefer can use eutetic plates and only need to operate the engine every few (4 or 5) days.
Running an engine to make electric , pump it into a battery , then take it out to operate any compressor can never be truly efficient.
Crazy how much energy is contained in a gallon of refined petroleum.
Tha'ts why a custom built reefer can use eutetic plates and only need to operate the engine every few (4 or 5) days.
Running an engine to make electric , pump it into a battery , then take it out to operate any compressor can never be truly efficient.
Although they can argue "mine is better than yours", none are really efficient.
It was a process, but the new refrigerator is installed and working great!View attachment 123021
It was a process, but the new refrigerator is installed and working great!View attachment 123021
For off grid applications, has anyone had success with Engel Freezers and Fridges?