holy grail solar air conditioning unit that isnt powered by honda generators and is

Yeah but not on boats, as already discussed: http://www.boatdesign.net/forums/bo...tioner-sun-holy-grail-42158-8.html#post538274
Perhaps on tankers or barges, where crew cabin volume is small, compared to the overall ship size, there's sufficient space on deck for solar concentration units and the weight of the system is small compared to the ship displacement.
And the solar array should be able to survive this: http://www.youtube.com/watch?feature=player_detailpage&v=BX3kFCgvKp4#t=95s

 

I try to keep my decks shaded and will wash them down with bilge water on really hot days with water. I also notice that the paint I use can have a large effect on hull temperature.
I had been think of adding fans to move air out of bilges, I have about 2 feet height over the whole boat, and it is much cooler down there. Also helps get humidity out of there.

 

Well, that depends on the heat load, doesn't it?

If the idea was to cool a relatively small volume, and if the heat load was reduced by circulating sea water through the deckhead/cabin lining (as already discussed) then it might well be possible to get the last bit of cooling needed from an absorption heat pump.

The main problem is being at anchor, in my view, rather than when sailing. A foldable solar concentrator, of the sort used on portable solar cookers, could be used. 12 kW is a lot of cooling for a small boat. In essence what's needed is enough cooling to get rid of most of the heat input from the sun and surrounding air movement. If we can get rid of the insolation heat input with water cooling, that removes around 800 to 1000 W/m² of heat input. We then only need to get rid of the heat input from hot air movement and the residual solar heating that gets through the sea water cooling. My guess is that this will be quite a modest load, probably no more than a kW or so.

 

It's just that I tend to think off-the-shelf... Nothing in the size smaller than 12 kW seems to be available on the market, and even that 12 kW chiller has a weight of 790 kg (the link in the other thread).

Robur (www.robur.com) makes units with 35 kW cooling/heating power which weighs 400 kg. That is more encouraging from the point of view of downsizing to 3-5 kW required for boat ambients, but remains a fact that there is still no product of such small size on the market.

Considering the very high cost of residential machines, it is possible that boating market is just too small to justify the R&D and production costs for a very limited number of units which could be sold at that price.

 

It would be nice to be able to design a boat from the get-go to have great passive ventilation qualities. Obviously, a thermally-conductive hull would be ideal, and bilge/holds/hatches would be designed to enhance convective passive airflow. Make the cabin roof an inverted-V design to enhance airflow to the peak, and released through a roof vent. Paint all sunlit surfaces white (I have done this on a personal boat which resulted in significant benefits). Use white bimini tops over open decks during the heat of the day. Even large golf umbrellas can help (but why don't they make them in white???).

I believe airflow is an even greater harbinger of comfort than air conditioning. If a person is not subjected to cold air conditioning every time they step into a cabin, their body becomes used to higher ambient air temperatures and they are more comfortable inside or outside. Add airflow and you can stay quite comfortable in 30C temps (just remember to drink plenty of fluids!). If you've worked 12-16-hour days out in a nice seabreeze in 30C temps, you will know what I mean!

Earlier in this thread, someone made a comment about how automobiles have a difficult time with cooling. When I was younger, I drove a '67 Plymouth Fury that had amazing ventilation from the outside. Open the vents and you got a rush of air around you. Although the car had air conditioning, we never used it because the air blowing around you kept you quite comfortable. Every other car I've been in has wimpy ventilation - little thought is given to the vent intake and the piping goes through too many convolutions by the time it reaches the cabin. The designers rely on electrically-driven fans to provide the airflow rather than natural airflow.

Point being, ventilation can be designed to provide comfort without the need for air conditioning!!!

 

I agree, the market doesn't directly provide for low power AC units, but they are out there. My car, for example, as a small electric AC unit. The pump quite small and operates virtually silently. It's powered from the main battery (being a hybrid this is a high voltage supply) and the system is sealed for life, rather like a refrigerator. It would probably provide adequate comfort cooling for a modestly sized boat, particularly if used in conjunction with pre-cooling with circulating sea water.

It may well be possible to run such a system from solar panels, depending on the duty cycle between cabin cooling requirements and sunshine - I doubt that it would do better than maybe an hour's cooling for three to five hours of sunshine.

The parts to make a low power DC electric AC system are available, even if only as spares for cars, so all that's needed (and I acknowledge that its a big "all) is for someone to package these off-the-shelf parts into a small boat system.

 

Jeremy, do you have any information on the ac unit in your car? I'm looking for units just like that.

 

Jeremy,

That borders on brilliant my friend. Hot, bright sun, lots of A/C use and lots of solar gain.

As we share similar climates you can understand my exuberance for your system.

Cheers,

-Tom

 

The system uses a Denso sealed electric AC pump, coupled to a standard sort of condenser radiator in the grill and an evaporator in the heating/cooling unit. A bit of Googling on Toyota Prius and air conditioning should yield some information. I remember reading a presentation on the web from Denso about the system a year or two ago, but can't find the link right now.

The same sealed electric AC system has been used on the Prius since 2005, so there are a fair few of these systems around now.

 

There was a push several years ago for the automotive industry to adopt 36V or 48V electrical systems. The understanding was that peripherals such as the AC pump, the PS pump and cooling fan would be more economically powered by electrical rather than mechanically driven, since mechanical is always 'on', at least for PS. There was likely pushback from the industry since this would add cost to the final production units. It will likely return as fuel economy standards push higher.

I imagine this development was in parallel with hybrid technologies. There may likely be several sources of DC-powered AC systems available, or ready to be put into production and marketed.

 

Thank you very much. I'll have a look at them.

 

CatBuilder, take a look at these and see if they might be a possibility. You probably need 4 and you could design a chair railing out of Teak or Mahagony to some what hide them. Also, I've seen them cheaper.http://flagshipmarine.com/rooftopac.html

 

By far those are the most simple, Rasor. That's what I first thought of. However... the wife pulled the plug on them for being ugly.

 

Ugly on the inside or the outside??? You can hide them on the roof. Also if one goes out your not dead in the water which is a big plus. Also sound is lessened with roof mount.

 

I couldn't agree more... and the install.... no seacocks! That would be ideal!

But... the big boxes on the deck would look like crap. There would be several of them on each hull and probably a pair on the top. The boat would look like this on the side with the least units.

On one side, there would be 3 of them.

Seems like a no go to me.