Water cooled Air Conditioning Condensor

[Oceanride007]

You know its been hot when you regard 37DegC as a cool change. Anyway am now contemplating a Airconditioning unit, while on the pick, will get a small petrol driven alternator.

Unfortunately it does not appear we can get dual ducted portable AC units in Aus.
Window system not so easy to fit.
Am thinking of a Split system, but with a twist am thinking of replacing the big bulky Air cooled condenser with a water cooled condenser.
Think could make a condenser out of copper pipe.


Can anybody give advise on surface air of cooling, ie water is more effective at taking heat away, surface area does not need to be so big.


Comments on the ratio of cooling areas, and has anybody else done this.

[dkenny64]

not sure if I follow your thinking..


you want to run an AC compressor from an engine? kinda like in a car?
but instead of using air to cool the condenser you want to use water? right?


if that's right..
yes it works...
most boat HVAC systems work this way..they just run on AC power..
so..get a old HVAC from a boat..strip out the condenser..
get a car compressor(runs on a engine). the expansion valve and dryer..
put it together.. R134 would a good freon to think about for getting the parts
most car systems use R134..cheap and easy to get


-dkenny64

[billknny]

Originally Posted by Oceanride007

You know its been hot when you regard 37DegC as a cool change. Anyway am now contemplating a Airconditioning unit, while on the pick, will get a small petrol driven alternator.

Unfortunately it does not appear we can get dual ducted portable AC units in Aus.
Window system not so easy to fit.
Am thinking of a Split system, but with a twist am thinking of replacing the big bulky Air cooled condenser with a water cooled condenser.
Think could make a condenser out of copper pipe.


Can anybody give advise on surface air of cooling, ie water is more effective at taking heat away, surface area does not need to be so big.


Comments on the ratio of cooling areas, and has anybody else done this.

Of course almost all purpose built boat A/C units are water cooled, because it is so much more efficient, and it give s you someplace to dump the heat where it doesn't just blow back in the boat.

But you have given us not a single actual piece of data to calculate the heat transfer area you would need. How big an A/C unit are you thinking about? What is your maximum water temperature? Will you custom build your exchanger or buy one off the shelf? What will you use for tubing if you build one? What will you use for a water pump?

All this assumes you have experience with actually piping and charging an A/C unit...

While I do understand the appeal of a DIY project, honestly, you would be better of buying one off the shelf where all these calculations have been done for you.

[Oceanride007]

Excuse me, Ist off thinking off the shelf split air Con m/c about 3.5 KW, they are cheap enough to convert to water Cooled. Am unfamiliar with any off the shelf AC units with SW cooled condensor, sure I can do a search but such a specialised unit, would likely be imported.
Definetly not Engine Driven.
AS regard ratio of Condensor surface area, I'd Imagine that a 10KW unit would have double the condensor area of a 5KW unit, same proportion as Water cooled condensor.

I could take a guess and say a Air cooled Condensor is at least 8 times the surface area as a similar sized Water Cooled unit.

And yes have had experience on water cooled refigeration. But not some of the engineering.
There are practical people out there, some may have access to a book.


Then again I suppose I could look up the specs of a similar sized, water cooled unit.

There you are answered my own question. But any useful comments would be appreciated.

[RaymondR]

I'm thinking along the same lines myself.

Nigel Calder wrote a book called Refrigeration for Pleasureboats about building eutectic refrigeration systems using an engine driven auto aircon compressor. He goes into a fair bit of detail on the design and fabrication of water cooled condensers of in chapter six. The books well worth having for the wealth of other information on refrigeration if you are interested in it.

[OzePete]

Yes water cooling is far more efficient at disposing of heat, but a split system off the shelf has been engineered to operate at high discharge pressures like well over 200PSI. It is not just a matter of tacking on a more efficient condenser, the entire system has to be engineered to suit and for that to happen you would need to build from scratch and able to engineer same.

Billknny sums it up well, buy a split system off the shelf, fit it and enjoy...(or just move into the Cooktown pub until the wet is over, no drama!)

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[valhalla360]

By the time you cobble something together, I'm betting you could just get a marine unit for less money and less hassle and it will hold up better.

[Sailmonkey]

Oh look, water cooled condensers off the shelf.....

http://www.freezetec.com.au/products...ed-condensers/

[billgewater]

If you purchase a split system off the shelf system, it can be used while in a marina where you purchase 240 VAC power. It won't disturb anyone. If the condenser is on deck, remember that it is prone to corrosion as they often have both copper and alloy components. The sheet steel "boxes" also have a limited life. However, if you run it from a genset, you need to ensure that the gen set will provide the large starter current needed for the system. A frigie chap may suggest a bypass at start up to reduce the current demand.
Using a water cooled condenser has some big advantages but cost isn't one. Copper nickel alloys are used and these alloy exchangers are expensive.
Also in the tropics, water temperatures can be very high particularly in shallow dirty river water which is a Cooktown feature. So when purchasing a water cooled condenser, make sure you are aware of this so water flow rates adequate.
I use a home made water cooled condenser. You need a steel pipe of about 10 cm outside diameter, a lathe and a coil of half inch copper pipe. You put the steel pipe (about 80 cm long) into the lathe and turn it at a very low speed. You feed the copper pipe onto the steel pipe making a close spaced helix from one end to the other. Turn the copper tube and return the spiral. You may build up possibly three layers of copper spiral wound tubing. (Mine use two layers.) Ensure that the two ends are protruding at the same end. Take the copper spiral off the steel mandrel. Some joining may be required, to retain the overall shape. Use plastic.This spiral arrangement is placed inside a 200 mm PVC tube with a glued on end cap at one end and a screw on end at the other. The two copper pipe ends come out the sealed end. You will need to work out how this will seal. I used all plastic fittings. Some glued in with backing washers and threaded parts on the outside to allow off the shelf fittings. The copper tube carries the refrigerant gas/liquid and will undergo expansion/contraction during use so the two end seals need to be "flexible".
At the other end, I used a large screw on cap. This removable cap has the water inlet and outlets (the inlet is connected to a soft hose that transfers water internally to the other end). You will also need to install zinc anodes and this is best done on the flat surface of the screw on end cap. You need to run a wire from the external anode connection to the copper pipes at the other end to complete the protection circuit.
The two end copper pipes will need to be joined into the discharge and return refrigerant lines and I have used flexible car A/C hoses and fittings plus I also have installed close off valves to isolate the copper pipes and others to isolate the remaining refrigerant plumbing.
If you mount this vertically with the water/anode end at the top, you can easily replace the zinc anode(s). Make sure the zinc anode does not touch the copper pipes. A drain at the closed end base allows the system to be flushed.
I also allow the system to be completely drained when A/C isn't needed which prolongs the life of the copper pipes. This system has been in place for over 30 years. The only drama occurred when I inadvertently connected the water supply up to mains pressure and it simply blew the end cap off! Embarrassing.
My system uses a dedicated Tecumseh 1000 engine driven compressor so I generally don't run it in marinas, but it works well at sea.
The heat exchanger described can be used for freezers or AC systems. I built the exchanger simply because it was more cost effective than the copper nickel alternatives. It is a mess of pipes, fittings and valves, but at least I can manage any repairs. It is also bulky.

[170122]

we were able to install this MPS 4200 BTU, we are able to stay dry and comfortable inside a 48 sail boat
Ebay

[rbakerflkeys]

I am a Marine air service center. I have dozens of used cooling coils sitting on the shelf. You may check your local airconditioning shop and see if they have saved any and are willing to part with them. I give mine away.

I have built several engine driven, multi air handler systems with good results. I have also built several chiller systems that cool an antifreeze solution then circulates the chilled water to the evaporator. This is a little more involved because you need an additional pump to circulate the aintifreeze water.

Consider using a rotary compressor instead of a reciprocating piston type. they are much easier to find and more efficient.

rparts.com has a bunch of dyi parts.

Richard

[warrior 90]

Originally Posted by Sailmonkey

Oh look, water cooled condensers off the shelf.....

Seawater Cooled Condensers – Freezetec

Yes, I think that´s the right direction.....

https://packless.com/



water-source condenser coils operate very effectively as either refrigerant condensers or refrigerant evaporators when transferring heat with water. This makes them an ideal choice for both water-source heat pumps (WSHP) and water-cooled condenser applications.

https://packless.com/products/condenser-wshp-coils


This tube might even be more interesting.....
designed specifically to remove heat from the superheated refrigerant discharge vapor of air conditioning, refrigeration, or heat pump systems for the purpose of heating potable water.

https://packless.com/products/double-wall-condensers


There is also a promising link to a software assisted design tool that might be of help. Looking a bit closer it seems to me that at least half of the bicycle is already invented.
Using our highly accurate coil simulation we are able to find the perfect coil to suit your needs. This tool provides detailed graphs and accurate statistics to help you integrate our coils into your system.

https://packless.com/login?t=tools/coil-selection


They say....Packless products are used throughout the world. Our customers range from the giants of American industry to the small, one-man business.
>> Well, seems like they have a good product....of course also with a patent $$$$ protection

..... We are proud of our growth and development, but far more proud of the loyalty of our customers.
>> Sure sounds inviting ))
Remains to be seen $$$$ what they mean by a ONE-MAN business

[warrior 90]

Originally Posted by Oceanride007

*will get a small petrol driven alternator.

* ie water is more effective at taking heat away, surface area does not need to be so big.

Comments on the ratio of cooling areas, and has anybody else done this.

Yes, I can see Your point but the small !! PETROL !! engine driven alternator ?¿?¿ Don´t get it.....explosive and lot´s of noise

Oceanrider, I have not done this, but I am interested and have the digging on my list. It´s just not the Nº1 on my priority list right now

[warrior 90]

Originally Posted by rbakerflkeys

I am a Marine air service center. I have dozens of used cooling coils sitting on the shelf. You may check your local airconditioning shop and see if they have saved any and are willing to part with them. I give mine away.

THXs Richard, that´s COOL info
Do You have more info as to which manufactures used those specific condensers ?
https://packless.com/products/condenser-wshp-coils
https://packless.com/products/double-wall-condensers

OR SIMILAR ?

Yes that would be $$$$ COOL. I believe the rest of the info can be determined by the specs of the manufacturer model Nº...... after all it´s just another component of a system wiht a brand name.



I have built several engine driven, multi air handler systems with good results. I have also built several chiller systems that cool an antifreeze solution then circulates the chilled water to the evaporator. This is a little more involved because you need an additional pump to circulate the aintifreeze water.

Yes, more tricky... specially thinking about using the waste heat of the system also to make hot water. What do You think about a pump similar like that for the purpose.....
DC brushless magnetic 4,5 PSI / 190ºF or Chinese knock off ?

Sorry, I might be wrong. I am not familiar with the required pressure and flow rates.

http://www.marchpump.com/site/files/...893-0037-1.pdf




Consider using a rotary compressor instead of a reciprocating piston type. they are much easier to find and more efficient.

rparts.com has a bunch of DIY parts.


Richard

Yes, this idea also attracts me. On cars and trucks comes usually with a belt drive and magnet coupling. What are Your thoughts on driving such a compressor with a brushless DC motor ?

[Djarraluda]

To give an indication of the heat exchange efficiency, consider the essence of all heat transfer is "LMTD" i.e. The logarithm of the mean temperature difference.
So air at 37 degrees for an air cooled condenser vs water at say 27 degrees as the cooling medium.
These temps need to be considered against the actual refrigerant temp in the equation, so it depends on what refrigerant you are using.
Of course it gets one heck of a lot more complex than that, but it gives a crude indication.

Real issues happen if you overcool, as then the oil separates out and does not return to compressor. Do not try it yourself without some appropriate guidance.

If OzePete or Frigitec or similar can not help, I would be surprised.
Roger