Micro mini split?

soylentgreen

For my camper van I'd love to have a mini split : high efficiency, and the best ones use only 300w.

But my van is small and the physical size and watts used are a bit too large.

What I want is a half-sized mini split: a device that's half the size and weight and uses 150w (and only provides half the cooling capacity).

I've tried looking for tiny air conditioners but what seems to be available are industrial cabinet ACs which are expensive noisy and nowhere near as efficient.

Has anyone come across a micro split?

Skyko

Re: Micro mini split?

I wonder if you could hack a small brushless DC compressor like the Danfoss BD-50 into a small window unit air conditioner? It would definitely get down to your 100 to 150 watt figure and would be very efficient to run off a car battery or two. I do not know how much a BD-50 by itself costs....$200?

Photowhit

Re: Micro mini split?

Many years ago, 20?, had looked into designing a sleeping chamber to run off a Danfross all refrigerator kit for boats. It used a radiator fan driven type cooler inside the fridge. As ? I recall, it would be near $500 plus building a 4x4x8 insulated box, and still need a refrigeration person to do the final setup... I was assured it would work and even found someone else had done something similar.

Skyko

Re: Micro mini split?

Photowhit wrote: »

Many years ago, 20?, had looked into designing a sleeping chamber to run off a Danfross all refrigerator kit for boats. It used a radiator fan driven type cooler inside the fridge. As ? I recall, it would be near $500 plus building a 4x4x8 insulated box, and still need a refrigeration person to do the final setup... I was assured it would work and even found someone else had done something similar.

That would be the way to go if you could section off your van's sleeping compartment. You could line the sleeping chamber with 1" polyisocyanurate foam on the outside and then likely get by with 20 to 40 watts going into a 12V brushless compressor to keep it right around 65 degrees even when the inside of your van was 90 degrees.

It would actually be very cool (pun intended) to have such a comfortable place to sleep when parked in sweltering areas like the southern USA during the summer.

soylentgreen

This is the idea that I can't drop.

More info: NREL has a interesting document (related to Electric Vehicles) talking about A/C loads in vehicles:
http://www.nrel.gov/docs/fy00osti/28960.pdf

Some points:

* automotive AC units are assumed to have a COP of 2.33 (COP = cooling watts / watts used).
* 7KW of cooling is the maximum cooling load, but these are sized for "worst case" scenario: Arizona in full sun with 120F ambient temperatures.

Many of us insulating our RVs will do much better than this, and not be in such harsh environments.

My vehicle already has a perfectly good air conditioner (engine / belt driven).

My question is this : Is there any practical way to re-use this existing equipment but at a much lower power?

I'm imagining some sort of "while parked" mode in which we use PV panels to run the car's AC system, but at about 1/10th the load : e.g. run the compressor very slowly, run the radiator cooling fans slowly, and run the interior fans at low speed.

Anyone thought about this?


For example: what if I removed the existing belt-driven AC compressor, and replaced it with a DC-inverter technology compressor. Then, while driving I could run it at 3000W (full cooling) but while parked, could run it at 300W. Add some additional circuits to run the radiator fan and ventilation vans at super low speed, and Voila : a high efficiency, lower power AC system.

(My other car is a chevy volt, and it uses an electric AC compressor, so I know such devices exist).

In other words: use the existing components to emulate a mini-split AC.

BB.

I am not sure I would bother with an automotive A/C system...

There is at least one DC version of an off grid Mini-Split:

http://www.hotspotenergy.com/DC-air-conditioner/

I don't remember if anyone here has tried one yet.

-Bill

soylentgreen

Thanks, Bill : I think there a lot of options for class A and C RVs, but the Class B's really need some help.

Small spaces (well insulated) probably need only a 300W AC unit, but the only mini-splits that run at 300W are still large size format. So I'm trying to find the magical trifecta: Small, efficient, cheap.

westbranch

looked at these?? http://www.dcairco.com/product/trucks-airconditioning/dc-9001-12-24-vdc-rooftop-air-conditioner

unseenone

I posted a similar product on another thread a while back. Very efficient DC system. Something like that seems like the way to go.