sch911 wrote:
RV refrigerators are primarily Ammonia Absorption cycle, not LP. LP is used to power the cycle in the form of heat. So is 12v power. When it comes to actual energy consumption (power used to cool) the Absorption systems are way more efficient than compressor based residential units. But the trend is now to go toward safer technologies for RV's like residential refrigerators with inverters, and large battery banks.
In a purely thermodynamic sense, as in total energy in to cooling output, absorption fridges are much less efficient than modern compressor fridges, by a factor of maybe three or so. There is literally no contest there. If you compare electricity usage on 120V power (where the RV fridge is not using any propane), the power consumption is significantly higher than a residential compressor fridge. If the absorption fridges were significantly more efficient, then residential fridges would generally use that system to be more energy efficient.
The advantages of residential fridges in RVs are better cooling, particularly in tough conditions (high ambient temperatures), generally larger food storage capacity, and lower cost for the fridge itself. The advantages of absorption fridges are much less electric power usage when off the grid, since the energy for the actual cooling is coming from propane rather than battery power, and (for some) quiet operation. If you are camping with hookups, or in situations where you'll be running the generator anyhow, the residential fridges are compelling. If you'll be boondocking or dry camping, and don't have a pretty good solar setup (or will be in an area where solar power is less practical, such as wooded areas), then an absorption fridge is probably the better option.
