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Charging R600a

09/13/2015 6:34 AM

Moving on from my peltier air conditioner project which consumed 900 to 1000 watts at 24 volts, I wanted to get into phase change systems. The system will consume about 100 watts.

I was wondering how to get the refrigerant into the system. Do you just suck out all the air and then run the compressor as you are putting the refrigerant in looking at where the ice is forming on the evaporator coil and then stop filling before the ice starts getting close to the compressor? I have no gauges or temperature probes. The system is using a filter drier and capillary tube removed from an old fridge. I heated the drier up and passed air through it and smoke and moisture came out.

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#1

Re: Charging r600a

09/13/2015 7:44 AM

entertaining post

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Power-User

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#2
In reply to #1

Re: Charging r600a

09/13/2015 7:48 AM

Take it you are not in to refrigeration?

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#3
In reply to #2

Re: Charging r600a

09/13/2015 8:02 AM

how about a 20 year HVAC contractor

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#4
In reply to #3

Re: Charging r600a

09/13/2015 8:05 AM

The idea can't be that bad, I saw a video of someone using air duster as refrigerant. It worked well.

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#8
In reply to #4

Re: Charging r600a

09/13/2015 10:37 AM

And how do you re-use the air duster when it is empty? Even air gets cold when it is decompressed. You need a closed system.

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#9
In reply to #8

Re: Charging r600a

09/13/2015 11:06 AM

The person actually put the contents of the air duster into a refrigeration system instead of the r134a that it was designed for. This is probably not good for the compressor. https://www.youtube.com/watch?v=mKmc7WObJJo

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#10
In reply to #9

Re: Charging r600a

09/13/2015 11:16 AM

The contents were probably butane or propane. No, not good.

Or some type of di or fluoro ethane. Not good either.

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#11
In reply to #10

Re: Charging r600a

09/13/2015 11:29 AM

R600a refrigerant is just refrigerant grade butane and the compressor I have is designed for this. I'm just not sure whether the compressor should be running while I put in the refrigerant.

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#12
In reply to #11

Re: Charging r600a

09/13/2015 11:33 AM
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Power-User

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#13
In reply to #12

Re: Charging r600a

09/13/2015 11:48 AM

Based on reading that it seems that the whole thing should be safe as long as it is not being operated in an enclosed area. The system will be open to the air and will have air flowing around it.

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#17
In reply to #11

Re: Charging r600a

09/13/2015 1:42 PM

You should eliminate the contained air which has a behavior . different from the one the fluid you use has. You should flush with the special fluid long enough to be sure that ALL air has been replaced. This you can do ONLY with the compressor running!

You learned with the help you got that you should not do what you intend. I am surprised nobody explained how a refrigerator works. A couple of days ago a new participant had a very nice word about how engineers react to questions: they will give all possible opinions but forget to answer the question. I am may be not enough engineer because first I try to give the answer. However you should take into consideration the different opinions some could be of interest.

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#18
In reply to #17

Re: Charging r600a

09/13/2015 2:59 PM

I will have the whole thing built and working by the end of the week.

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#21
In reply to #11

Re: Charging r600a

09/13/2015 7:28 PM

Yes the compressor should be running and the system pumped down to a high vacuum as well.

Slowly feed the refrigerant into the low pressure side of the system and watch your evaporator temperature. Once the temperature reaches is minimal point add just a bit more and call it good enough. You may or may not get frost to develop. That depends on the system capacity and how much heat is being exchanged at the evaporator when you are charging the system.

As for legality meh ... Personally owned and built systems not being used as part of a central heating/cooling system for a home or in a tightly enclosed area the odds are no one of any consequence will ever care what he is doing and how or why.

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#22
In reply to #21

Re: Charging r600a

09/13/2015 9:40 PM

The system needs to be purged, evacuated and a filter drier installed....you would never run the compressor during initial charging....the unit is charged statically, then adjusted after running for 10-20 min by following manufacturers recommended method....

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#27
In reply to #22

Re: Charging r600a

09/14/2015 12:51 PM

Interesting being all my old school AC books I had access to years ago said to do it on the go with the compressor running unless you have a transfer pump and scale and know exactly how much refrigerant a system needs to which that was how I learned it and have been doing it for 20+ years now without a single issue ever.

About the only pre charging I have ever done was to let my tank pressure and the system get close to balancing out before starting the compressor.

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#24
In reply to #4

Re: Charging r600a

09/14/2015 10:34 AM

"AIR-DUSTER" is not air. It is R134a refrigerant.

Be careful as there are many refrigerants and refrigerant lubricants that are not compatible which can/will result in an explosion. This can be fatal to anyone and everyone in the immediate area.

The correct way to perform the procedure is to first determine if there is any danger from refrigerant and/or lubricant incompatibility issues.

If there are any compatibility issues you must identify and use the correct flushing agent to remove any residuals before introducing the new refrigerant into the system.

Once the system has been properly cleaned a vacuum must be drawn on the system to remove any moisture.

Charging of the system should be accomplished using a sensitive scale or Delta "T" measuring device.

Charging a system by feel or sight is possible but usually can only be performed somewhat accurately by a very experienced, knowledgeable technician.

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#25
In reply to #24

Re: Charging r600a

09/14/2015 10:40 AM

I will be using R600a in a compressor made for R600a. I will use another refrigeration compressor as a vacuum pump.

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#20
In reply to #2

Re: Charging r600a

09/13/2015 7:15 PM

Sounds about as competent and qualified as most licensed HVAC techs I have dealt with over the years.

'Well ya see I jus' show up with this gauges and hosey thingy hook it up where evers I can and acts like I is put'n some of dis' here, stuff from dis espensive looking can, 'Empty can o'cuse' wink wink nudge nudge, in ta what evers those hose thingies would connect to ten' makes up a big number and tells da cus'mer dat what deys owes me.

Den if deys calls back en a dey or so an seys der thingy still aint workin's I tells dem dey needs a new un an I makes up a really really bigs number and tells dem dats what it costeses. '

An dat's hows ya does HVAC work!

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#33
In reply to #20

Re: Charging r600a

09/16/2015 10:29 AM

The really sad part of this is that the scenario you laid out all too often is true in today's world. It is getting to be almost impossible to find a competent, trustworthy technician in any field. Most are "black-box throw away" parts changers. It isn't that they are not intelligent enough to learn it's either the company they work for will not spend the money for proper training or the technician trainee doesn't care enough to apply themselves.

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#5

Re: Charging r600a

09/13/2015 8:36 AM

Although you can use Peltier devices for air conditioning, they are far inferior to the conventional refrigerant gas method, and are just a way to spend extra money on electricity and costly peltier devices for some sort of show project.

There are places where peltier devices are used, such as spot colling of electronic parts for which a tiny 1 watt compression based fridge would be too complex and costly.

The adsorption methods are better, but they have still lost out in the efficiency race, and only find application where electricity is scarce and heat is available - solar fridges etc.

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#6
In reply to #5

Re: Charging r600a

09/13/2015 9:00 AM

The peltier air conditioner I had was run on solar but as you said, hopelessly inefficient. The new system I plan to build will exchange heat with a large underground water reservoir and will be used for heating or cooling water. I hope it will be able to create very cold water for a compressed air dryer I have. The refrigeration compressor consumes 80 watts and should in theory be able to move 196 watts EN 12900/CECOMAF)or 239 watts (ASHRAE)

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#7
In reply to #6

Re: Charging r600a

09/13/2015 9:15 AM

well, a resting person = 100 wats heat, so it will cool two people under a blanket...

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#14

Re: Charging r600a

09/13/2015 1:05 PM
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#15
In reply to #14

Re: Charging r600a

09/13/2015 1:18 PM

I have seen those small low voltage compressors before. Sadly, they are very expensive. My setup is only intended for chilling water for an air dryer. Nothing massive.

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#16
In reply to #15

Re: Charging r600a

09/13/2015 1:34 PM
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#19
In reply to #14

Re: Charging r600a

09/13/2015 3:28 PM

I looked at their site = zero price data.

This usually indicates a high price.

I see they use high speed pulse width to drive the motor, which makes it a lot smaller.

There was an Australian company that used a small compressor, like an aquarium compressor, for small personal coolers or fridges.

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#23

Re: Charging R600a

09/14/2015 10:01 AM

Try compressed ammonia! That works when you heat it up. Put a 100 watt heater in the system, fire it up and stand back!

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#26
In reply to #23

Re: Charging R600a

09/14/2015 11:07 AM

I will leave you to do that for yourself.

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#28
In reply to #26

Re: Charging R600a

09/14/2015 2:54 PM

I just threw away 2 small 250 watt refrigeration systems that use the method I mentioned.

They were good units but I'm cleaning out my garage soooo they got TOSSED!

Wait.... Their still sitting out front waiting for the trash pick-up!

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#29

Re: Charging R600a

09/15/2015 2:08 AM

You were not supposed to use the old filter drier,instead buy a new one. Make sure your unit is tightly sealed without any leakages.If at least you have a charging hose then it will be much easier to work on your machine.Try by all means to eliminate foreign particles from outside.GOOD LUCK.

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#30

Re: Charging R600a

09/15/2015 8:03 AM

Please do report when it is running how much power consumption and cooling you get out of it...I may want to replicate this for a boat. I will use a heat exchanger under the boat to get rid of excess heat.

Drew K

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#31
In reply to #30

Re: Charging R600a

09/15/2015 11:50 AM

Will do, just waiting for the stuff to arrive. For your application you may want a more powerful unit.

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#32
In reply to #31

Re: Charging R600a

09/15/2015 12:13 PM

Probably...the water is warm enough to swim in so it will not take as much heat as the system would want to discharge.

I have been looking around for a low current method of cooling the boat. I would like it to run on batteries assisted with solar and the occasional generator run.

Drew K

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