Evaporative A/C

[shipwreck66]

Ok Phil, here is your update. I Purchased a Kuulaire Evaporative AC to put on my boat to run off an inverter. Today was 100 % humidity so unit should not have cooled but hatches were shut and it kept interior comfortable when it was 89 degrees outside. When loaded with ice cooling effect is even better and holds 1.8 gallons. Only draws one amp per hour and requires no exterior venting. Not as cold as a refrigerated unit but if it works on a really humid day should do adequate when July roles around. Sure beats a fan and only cost $100. Will run about 8 hours on a single fill of water so we will turn it on before we leave slip and leave on while sailing. Phil if this could be adapted to use the ice box for cooling source this might just work, I think ice box holds about eight large bags of ice plus drinks.

 

[philwsailz]

I have started my ice-powered condeinsing unit... I am copying from my C-27 refurb thread:

I also have started a McGyver project of sorts. At the very first of this forum thread, it was alluded that I wanted to goof around and see if I could successfully build an air conditioner system that was not evaporative, (i.e. swamp cooler ) in nature. I want to be able to use a closed loop of refrigerant that would be pumped through a heat exchanger that I could blow air over to cool. The device would hopefully chill the air enough to dry the air, resulting in the need for a condensation drain, just like a modern AC. The cold source would be simple ice.

Yesterday I started..... *bwaaaa haaa haaaa haaaa*, (mad scientist laugh)

Here is the bill of materials so far:
1 plastic battery box
1 copper automotive heater core
some scrap sheet ABS, (.250" thickness)
Spare sanitary plumbing hose, 3/4"
1 spare bilge pump
1 spare big cube ice chest
1 spare bilge blower from parts donor boat
bilge blower tubing from parts donor boat.

My plan so far:

What I am doing first is to create a heat exchanger box from the battery box, scrap ABS, and heater core. Once I have that built, I will plumb it with a supply and a return line. I will also install a small fitting in a low spot in the battery box for the condensation drain. The drain will go to the shower sum installed in the boat previously.

I will use the donated exhaust blower hose to plumb the boat for air duct and return. I will keep these runs as short as possible. The heat exchanger will sit in the port lazz, on the shelf created by the installation of my modified galley/wetbar. It will be connected to the boat interior by a very short length of hose, or I might just cut a hole through the galley/wetbar back splash and pull the heat exchanger up tight to it, with a vent grill of some sorts for a finished cosmetic.

The cold source, (ice in an ice chest) will be mounted just aft of the heat exchanger in the port lazz. The donated bilge pump will sit in the bottom of the ice chest, and wil be connected up to the heat exchanger core by a short length of the sanitray hose, (you don't need sanitary hose, but that is what I have), and the return from the heat exchanger core will simply return to the ice chest.

I will fit a ball valve drain on the ice chest drain plug, and it will drain into the shower sump, either with a separate fitting, or combined with the heat exchanger's condensation line.

A simple switch will energize the pump and the fan, turning the system on. I may find that either a thermostatic switch or a rheostat might come in handy to control the amount of cooling, allowing the ice to last longer than if left running full time.

I have attached pics off my start on building the heat exchanger. As you can see it is simple, but I believe it is no more simple than any heat exchanger. Hot side, exchanger, cold side....

A bonus benefit I perceive is that if this works, I have an opportunity to extend the plumbing and be able to tap the engine cooling line for winter sailing and be able to provide heating to the cabin in wintertime. Granted it will requrie running the motor, but there are other ways to heat water too...

Anyway, enjoy, and we can start a new thread to keep status updates going elsewhewre if folks deem there is merit.

Enjoy!

Here are the pics of the heat exchanger in develpoment:

 

[philwsailz]

Herer is a crude pic of how I envision the system working at the moment.

 

[shipwreck66]

At my wife's request, I surrendered when the average evening temp rose to 98 degrees with almost the same humidity. The window unit is back on the boat for the summer, and works really great, at dock. I did invest in a much higher capacity fan for the boat, a Vornado, and it beats the heck out of that wimpy 12v thing WestMarine sells. The swamp cooler is sitting next to me as I type this, awaiting an upgrade. Since the water tank is on the bottom and the water pump sits in the tank, and we know it works fantastic with ice, why not remove water tank, install unit on top of a 8qt. ice chest with the pump at the bottom? With 103 forecasted for this weekend, good time to get desperate. By the way, the ice machine does work good in boat, but does put out heat on the side, a slight problem. Many are awaiting the outcome of your experiment, let us know how it turns out.

 

[Joe Diver]

I like the idea, and it's fun to experiment and all....but a small window unit can be had for $100 or less....I've seen them as cheap as $89 and measure 13x13x16...5k BTU's....even on my C25 would be fairly out of the way to step over at the base of the companionway.....

But....Phil and all....I do want to see your pictures when finished!

 

[DanM]

Phil,

I'm also very curious to see your results, I love the fact that your willing to put some effort into a new idea, very American!

I've never used a swamp cooler, and only heard of them a few years ago when I moved to the south. I have had to learn something about weather though for my job, so I guess I'm trying to figure out how one might cool the interior of the boat if the humidity is very high? They do rely on evaporation to cool correct? So if the humidity is already 100%, in other words the air is already holding all the moisture it can, there won't be any evaporation, therefore no cooling right?

Looks like Phil's idea will remove some moisture from the air (at least untill the ice is gone) and make the cabin feel cooler due to the ability of the ambient air to hold more moisture (easier evaporation).

What I like about Phil's idea is that maybe you could use it on an overnight at anchor. Seal up the boat by closing all the hatches, run the system to dehumidify the cabin and cool it slightly. Run your cabin fans to enhance the evaporation of the occupants and by the time you run out of ice it might just be time to wake up anyway. He may be on to something here, and I'm excited to see the results!

Take care, DanM.

 

[DanM]

...Oh, and I guess I should also mention that I'm with Joe Diver on this one... at the dock I tend to use my little window unit to dehimidify and cool the interior of my Catalina 30. What I like about Phil's idea is it's low use of amp hours when away from the dock and easy shore power.

DanM.

 

[Joe Diver]

Yeah, the low amp hours make Phil's solution appealing for use away from the dock....but man, it's forecast to be 105 here today with heat index between 110-115....and nothing short of refrigerated air will cool that!

 

[philwsailz]

This would be refrigerated... The cold source is just above freezing, just like industrial chilled water systems. I just am nervous how long it will operate at 32 before the ice is depleted. That is the only question and since efficiency depends on temperature, it is difficult to calculate...

 

[shipwreck66]

Since all of you are familiar with the huge ice boxes already installed on these boats, except Phil's, I am wanting to use that capacity as my cooling source coupled with a swamp type unit to blow cold air. the unit only draws about 10amps using an inverter, giving me about 9-10 hours on the dedicated battery,cold water is pumped to the top of the unit, runs down the pads where normally evaporation takes place for cooling, while forced air blows cooled air out. My Eagle Mtn. neighbor states the truth that at 103 degrees nothing but real A/C will work. I'm not even going to the lake today, but the window unit does just fine in the companionway. Someone in Rockwall has a Cruisair 5000 for sale today on Craigslist for $275 if anyone is interested. My wife likes the small compact size of the window unit, sits on floor under table when not used, not bulky or heavy.

 

[All U Get]

Why not drill 4" holes in the ends of a large ice cooler. Connect a variable speed fan to one side and have an inverted dryer vent on the other. The air would be cooled and dehumidified as the fan forces it through the ice . The air moisture could be collected and used or allowed to drain out into the sump.
All U Get

 

[shipwreck66]

That's pretty much what I would be doing using the boat's existing icebox. the water once melted and warm can be drained out. The icebox holds about 10 bags of ice, plenty for an afternoon or a night on the lake

 

[DanM]

Shipwreck66,

Do you have a large enough battery bank on your C27 for a 10a draw for 9 or ten hours? I saw 1a in your original post, but that must have been at 110vac?

I use two 6v golf car batteries in my C30 so I don't think I could afford the load.

DanM.

 

[Joe Diver]

I've got 210 aH in my bank, so I could do 10 hours and take the bank down 50%.....

 

[Stu Jackson]

Hey, Phil, doesn't salt water have a lower freezing temperature Make salt water ice...

 

[shipwreck66]

DanM, I've got a Group 31 battery isolated to power an inverter to power all the 110 plugs in the boat. Should it go flat, which thus far has not happened, I have the two main house batteries also. But the Group 31 will handle a 10 amp draw through the inverter for over 8 hours, plus fans, TV, and some LED lighting we put up at night. I'm figuring if it draws .7 amps at 110v then should be less than 10, even through an inverter at 12v, or do I have my math wrong? Thus far we have had many afternoons and evenings using this method of power and haven't run out yet. Stu is probably right, those of you in salt water will have better luck cooling, but what does salt water do to the water pump?

 

[philwsailz]

Hey, Phil, doesn't salt water have a lower freezing temperature Make salt water ice...

'been thinking a lot on this, (106 here and I am not going to the shop today...) and will postulate this. Some facts:
Ice as a solid will go as cold as you tell it to.
Ice will stay solid to 32F.
Salt will lower the temp of the liquid we are able to pump.
Salt melts ice
Pink antifreeze will lower the temp of the water we can pump
Pink antifreeze melts ice

These facts in mind I have reasoned there is not much point in trying to move a cold source through a heat exchanger that is much colder than 32F or we will freeze up the copper fins in the core of the exchanger.

We do know efficiency is greater when hot side and cold side are at the extreme opposition, so cold as possible is ideal and salting the ice will be an easy test. If we freeze the coil we over-did it.

The perfect blend will be ice as cold as possible, with max BTU available from it being as cold a solid as possible. From there you want the core of the heat exchanger as cold as possible WITHOUT freezing. This will be lower than 32F and will depend on how much heat we are trying to soak. The core itself needs to stay at 32 or just higher.

My original mental design included a closed system with pink antifreeze as the medium. I still plan on going there IF this direct water system proves workable. This will allow us to potentially pump a liquid below 32F without adjuncts. I'm considering pumping water first, as I have all parts here to build it now; net-zero cost. I am cheap and if this turns out a bust, I am not out anything but time.

I will also acknowledge the fact that an ice system will last longer installed on a boat that can cool on 110 shore power at the dock. While efficiencies are lower for a pre- cooled boat, the ice will be used for maintaining temp as opposed to chilling; the result should be that a given volume of ice should last longer. It will be easier to maintain a cooled boat when compared with trying to cool a hot boat. so, in summary, I perceive this as supplemental cooling, to maintain some level of comfort under way.

Post away, good thoughts all and I will keep you posted ad I go forward!

 

[All U Get]

So then if we pump raw water from deep water into the cooler over the reversed heat exchanger it will cool the pink antifreeze to 60 degrees or less in Maine. Even if the water source is 80 degrees, that's 30 less than 110 and should cool the cabin air in the south. Two pumps, two heat exchangers, fan, and some tubing.
All U Get

 

[philwsailz]

So then if we pump raw water from deep water into the cooler over the reversed heat exchanger it will cool the pink antifreeze to 60 degrees or less in Maine. Even if the water source is 80 degrees, that's 30 less than 110 and should cool the cabin air in the south. Two pumps, two heat exchangers, fan, and some tubing.
All U Get

You are on it. I will digress further, since this is public domain from what I can tell. I have Gleaned information from several sources over the last 10 years thinking about this. Say you have no ice. Say you have a source of deep water. Say you are at anchor in 50 or 60 feet,or who knows how deep. Say you are using a pump other than a bilge pump originally described in the thread so far... Who needs ice... What you need is a brick.

What is the temp gradient between air and the bottom of your anchorage? Let's remove Reynolds losses due to friction for a moment. If you suspend a supply hose just above bottom you can pump from the bottom and the only "head" you have to overcome is the elevation from water surface to pump... If you have 40-50 deg water you are probably going to achieve condensing cooling without ice...

What we have discussed so far only needs to be simply modified such that WHEN ANCHORED for the evening, all one might want to do is to toss a hose overboard and pump cold water up from the bottom to run through the heat exchanger.

This was my original plan 15 or so years ago, when on my first c-22 o was only looking for comfort when on the hook...

Go guys....... Who has deep cold water waiting to be tapped?

 

[Joe Diver]

That's gonna be wholly dependent on where you are.

Here in Texas we have a few lakes that are deep, more than 50'. As a diver, I've only personally experienced 3 of them: Possum Kingdom, Lake Travis, Canyon Lake. All of them have thermoclines, with Canyon having the most severe. They are very similar though.

Possum Kingdom, in the summer when the surface is 84....around 35' the first thermocline drops temps to 72. At 45' the next thermocline drops to 68. Around 60', the final thermocline drops temps down to 60 or so, down to the bottom at 85'. (varies between 75' to 90')

Canyon and Travis will be similar, with Travis having additional thermoclines down to 170' depth, temps in the low 50's or maybe even high 40's, not sure as I'm not a tech diver so don't exceed 130', at least on purpose or will publicly admit to.

Water clarity will have a significant impact on temps at depth, as well as source...for example, Clear Springs Scuba Park in Terrell...spring fed and not too deep...very clear most of the year until summer algae blooms increase turbidity. BUT...it has a wicked, and I mean wicked, thermocline. You can see that sucker....and swim along on top of it dangling your arms down into it. It's sharp, like a 20 degree change in just a few inches......