Most every product sold can have some spit and polish added to increase efficiency and/or efficacy. The designers put everything on a profit vs marketability chart and ultimately go with what will yield them the most profit, even if the choice yeilds .001 cents per product more profit, yet has a 2% loss of efficiency.
Every fridge out there can benefit from better door/lid seals, more insulation, and a condenser which can more easily release the heat it has removed from the box, to the atmosphere.
It seems a downright shame that so many fridge installs give little thought to this heat removal. I was able to reduce the comnsumption of a friend's household full size fridge by over 25% by modifying the cabinet into which it was installed so that the heat produced could simply escape easier.
now I spent several hours modifying the cabinet, and it will take years to make up in electricity costs what they paid me for modifying this cabinet, so it is certainly arguable that it was not worth the effort consumed
None of this really matters when one relies on the magical power grid at 17 cents per KWH consumed, they only seem to become considerations when moving away from that, to battery power and how to replenish those batteries and make them last an acceptable amount of time. It comes to generating more power, or using less of it. With the prices of solar now, it seems easier to simply produce more, but using less is wiser, it just takes more thought and effort to achieve, and requires one not just rely on the factory having made the product as best as possible for the application.
The condenser can be passive or forced air over the fins. The fan which came on my VF is rated at .25 amps, actual consumption 0.12 amps once spinning.
It was mounted to pull air through the condenser whose fins are as closely spaced as a car radiator. Anybody familiar with computer fans and has played with them while running, will find that when one presents a restriction behind the fan, it gets louder, and moves much less air, much more so than presenting the restriction in front of the fan. So Why Did VF and most every other employer of the danfoss compressor mount the fan in this orientation where it is louder and less effective?
Because it is good enough.
The fan VF provided is rated at 72 CFM, has a sleeve bearing and consumes 0.12 amps.
I replaced it with the Noctua NF-f12, rated at 53cfm and 0.05 amps, and mounted it to push air through the restriction, as this is how it was designed, for high static pressure and low noise and electrical consumption. I had been taking duty cycle measurements and amperage measurements at the time I swapped out the fan, and the Duty cycle went from near 6 minutes to under 5, simply by using this 25$ fan instead of the cheapest fan that VF found at the time they assembled the fridge.
I was rather stunned that the effect was so dramatic, and the fan was quieter, and it consumed less than half the electricity of the provided fan. I kept taking measurements for 24 hours figuring the seemingly huge increase in efficiency was influenced by other variables, and it did settle into the 20 to 30 second shorter run times, rather than the 75 to 80 seconds I initially observed. Still, an impressive gain simply be changing the location of the fan.
Regarding insulation, I had temporarily added 3/4 inches of foil backed foamboard insulation to the sides of my fridge while I modified the cabinet to accept the slightly different dimensions of the newer fridge. I took my IR gun, found the outside of this foamboard insulation to be 80F, and pulling it off and shooting the sides of the fridge I found it at 63f.
Nothing quite like actual data.
It seems the household fridges/ freezers, can have even more spit and polish added for even larger improvements in performance, but there is that pesky inverter required, and its inherent inefficiencies.
can they be negated?
My upright front loader fridge, whose ergonomics i much prefer in my Van, well the door seals are not impressive, nor the design. The metal skin of the exterior of the box is exposed to the interior of the fridge, basically expoosing the coldest air to a surface shared with outside ambient temperatures. This seems rather asinine, yet the fridge consumption is extremely low, considering. But I believe there are huge gains to be had with a secondary seal preventing the coldest air being in contact with metal which goes under the door seal.
Why did they design it this way? Because it lent itself to production, was easy, and is simply good enough.
What kind of efficiencies can be gained in the dorm fridge on an inverter, well the same as above, but there is the inverter itself at 85% efficiency at best, and who knows what else could have been streamlined in the compressor controller electronics to eek out more efficeincy. Add to this the Standby draw of the inverter when the compressor is not running, and the effort/ electronics required to negate that succesfully.
Of course it can be done, and the prices of 12vdc compressor fridges do seem ridiculously high.
Adding foamboard insulation is so simple. Look into Nashua Flexfix tape. Some toothpicks or bamboo skewer can hold the boards in place while the corners are taped
Increasing heat removal from condenser can also yield vast improvements. This can be done with more efficient fans, or simply assisting natural convection, or by not restricting it by not giving any thought into the fact that the heat generated needs to go elsewhere.
Those with chest style 12v compressor fridges would do well to cut off the ciggy plug and wire fridge to fuse block with thicker wire, as the ciggy plug is doomed to fail and it turning battery powert to heat.
Also it seems that many will build enclosures to assist the ergonomics of a chest style fridge in a small space like a van, but give little though to the fact that they have obstructed airflow to the condenser and compressor.
