...and if it's warmer than 75F, it's a hot day.
For all those that say no, do you have or ever fly with your wife or girlfriend?
I don't have an RV-10, and my airplane doesn't need A/C. I have thought about getting one of these for my camper van though:
https://www.zerobreeze.com/
I wonder if it could be made to work if you could vent the hot air out to a low pressure area on the exterior. The nice thing is that you could easily remove it during the cooler part of the year. Also, if you don't have enough electrical capacity, you could run it on the optional battery.
ACs follow fixed physical laws. Based on outside temp and wanted BTU you can calculate how many kWatts of power you need to achieve that.
The other way around if you have the power consumption given by the AC manufacturer, you can calculate how many max BTUs the unit can make at a certain outside temperature. When I run the numbers for an RV-10, a good sized AC with 20,000 BTU will consume at least some 6 kW of power.
These battery or cigarette lighter powered zero breeze units have no chance to act as a decent AC.
But, what about the giant fan out front?!?
I do use the correct physical calculations, see the enthalpy diagram, but I recalled the wrong unit, it needs roughly 6 hp not 6 kw, the diagram you had says 5.2 hp, same thing, probably they assumed a different outside temp. The hotter it is outside the less BTU you make with same hp effort on the compressor.No on the red text, but the rest of your comments are correct. Occasionally the assumption is made that compressors require the same amount of power to operate as the heat energy contained within the refrigerant being pumped by said compressor. This is an incorrect assumption. The refrigerant carries much more heat, or energy, than the compressor consumes. Here are the curves from Sanden compressors (just an example; AFS uses a different compressor): http://www.sanden.com.sg/opencms/ex...n/images/pdf/Performance_Curves-xWebsitex.pdf
Read the attached explanation which has the compressor curves from the Airflow system. Note that at 2600 engine rpm, the compressor can pump up to 19,500 BTUh (5.7 kW) but requires only 5.2 HP (3.9 kW) to operate. A keen eye will also see that AFS's compressor is not as efficient as the Sandens.
Can take off hot engine on a 100 deg day and climb fully loaded with cyls at 400-410f at 500 to 700 ft/m. Around 430f if you push it 1000 fpm when it's that hot but that's not often. Normally see 380 CHT in the climb.
I'm happy like it is
Wouldn't ever consider it, when I have the wife onboard (which is quite often) she tends to shed clothes
ACs follow fixed physical laws. Based on outside temp and wanted BTU you can calculate how many kWatts of power you need to achieve that.
The other way around if you have the power consumption given by the AC manufacturer, you can calculate how many max BTUs the unit can make at a certain outside temperature. When I run the numbers for an RV-10, a good sized AC with 20,000 BTU will consume at least some 6 kW of power.
These battery or cigarette lighter powered zero breeze units have no chance to act as a decent AC.
Thanks Martin. I guess I should have clarified what I was suggesting. Engine driven systems in cars and airplanes are designed to bring the complete volume of air down to a comfortable level even in fairly extreme temperatures. They are kind of the benchmark for comfort.
The portable system I referenced would be more comparable to the ice chest type systems. Rather than completely cooling the cabin, they can provide some welcome relief by directing cool air directly at the occupants (probably 2 people max). As you mention, the cooling output is a fraction of the engine driven systems. Of course based on what this unit is, you have to have realistic expectations. Everything is a trade off.
Also, just to clarify, this style of unit was not designed by the manufacturer to be directly powered through a cigarette lighter. Users have measured power consumption anywhere from 140 to 165 watts on the higher settings. It is powered by the supplied 24V battery packs, or some users have wired up their own 12V to 24V DC/DC converters to run direct to vehicle power with adequately sized wire. Here are some various specs I was able to find:
Cooling output: 2300 btu
Unit weight: 16.5 lb
Weight for one battery: 12 lb
battery charge time: 5 hrs
Run time on high setting (per battery): 3.5 hrs
I see some possible advantages:
- Not cheap, but reasonable upfront cost
- Removable when not in use to save weight
- Ability to reduce temp a little before engine start
- No need to haul ice, and battery is ready to run anytime
- Charge in hotel
- Multiple batteries can extend run time
Having said all that, I think the manufacturers intentionally avoid hard specs on their systems because they don't compare favorably to conventional systems. Consumers often don't apply simple logic, and expect that when they say "portable air conditioning", it will somehow miraculously replicate the capabilities of larger systems. I put a lot more stock in the experiences of actual user's reviews. Also, keep in mind that some reviewers may have a vested interest. Buyer beware. Anyway, not for everyone (or maybe anyone), but thought I'd throw it out there.
I’ll put it this way.
I had a zerobreeze unit in my last RV10. The one I’m building now has a airflow systems A/C.
Good to know there is some real world experience out there. Hadn't heard of anyone trying it yet in an RV. Was it the model 1 or model 2? The new model increased voltage from 12V to 24V.
I had the version 2. 24v
Good to know it's been tried. Can't argue with experience.