Micro Air Conditioner for Motorcycle or mobile applications

[R123]

It is my opinion that 400-500 BTU's will not cool a rider adequately on any day that mechanical cooling is required. You will have massive external heat loads which you are not providing for in your design.

It is my opinion that no motorcycle is going to be able to supply sufficient electrical power to drive the equipment required to do this job. If it were me I would lean towards mechanically driving the compressor.

PHM
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I agree 100%. The average human PRODUCES 400 BTUH of heat. You need to calculate your external load in addition to the 400BTUH which is going to be many times greater.

[itsiceman]

How bout a CO2 tank that unloads liquid into some kind of HX

[Joel_Dude1450]

I agree 100%. The average human PRODUCES 400 BTUH of heat. You need to calculate your external load in addition to the 400BTUH which is going to be many times greater.

I plan on having a re-circulating air system, so the cold air stay within the person being cooled. Lets say 50% or of the air is re-cycled. Also the compressor has a COP of almost 4, lets say its 3. thats 300+ watts of cooling or about 1100BTU's.

A scooter like mine produces 8.9Kw at the crank. You may not know but there is a large empty cavity where a small coil can be installed in there if desired. if we steal 150 watts of power from the crank, the difference would be less than 2% power loss. this would be enough to power the entire unit

[Billy1948]

pretty damn cool.

[KazBach]

I imagine off grid, low power systems run into similar issues that amount to ... BTUs require a lot of power.

It's an interesting idea if you ask me. But probably not practical - just like my off grid ideas.

[Joel_Dude1450]

So if I could grab anyone's attention I would appreciate it very much.

Since I started this project, I bought a car, and suddenly i could drive around with AC, so this project was thrown in a corner, forgotten.

I did made some progress, as I was able to remotely control compressor speed and all functions of the system via Arduino and PC serial interface. I made my own evaporator out of frustration, from a 80mm PC processor heatsink, by removing the heat pipes and replacing them with tubing. It didnt work so well, it didnt absorb much heat.

I then finally got my hands on a small, full copper evaporator like this one:




its 80x80mm and soldered it to the system. Also, in the process, i cut the capillary tube shorter.

It worked really well. the first part of the evaporator ( about 1 inch of piping) would form a small frost and throw cold air.

However I was left with a few thoughts:
1) it would work really well at the beginning, it would get hot on condenser and cold on evaporator. after a few minutes, not so much. Maybe no enough heat to the system?

2) at full power, the compressor would kind of "choke" or make banging sounds, kind of like compressing liquid. but there wasnt enough refrigerant in the system, or else the entire evaporator would have to freeze and flow upwards to go to the compressor. So i never ran it past 90% RPM limit.

3) it developed a small leak. I could see about 1 drop of oil would form from the leak ( with UV dye). I tried fixing it but I could never do so. It leaked out and has been left to sit for 2 yrs, empty. Is the system ok? Do i need to flush it? is it ruined? I has never been opened, just lost its gas over time. Its been sitting in a room, indoors this whole time.

Anyone who has comments on those 3 points, greatly appreciated.

[rjk_cmh]

Can't help much without the basic measurements, like superheat subcooling and so forth. You should be able to vacuum it out after standing open, as long as you maintain low microns.

[Joel_Dude1450]

I guess I could fix the leak and vacuum it, but will the oil still be good? it runs on R134, regular car a/c gas.

Once i fix it and re-fill it i will take measurements. I have access to low side only, and i can measure temperatures of any point in the system. I should measure temps before and after gas goes in/out of condenser and evap? should i measure temps going in and out of evap/cond air flow?

I learned most of this 2 yrs ago, kind of forgot about it by now...

thanks in advance

[rjk_cmh]

What oil does it have, PAG, POE, PVE, etc? Some oils such as POE will disassociate when exposed to moisture, others will just absorb the moisture and offgas it again under low pressure.

[HVAC_Marc]

I'd use propane. But not the grill kind.

[2sac]

Buy a Mini Cooper convertible with a/c and call it a day.

[R123]

That’s a water coil, not a refrigerant evaporator coil. What kind of metering device do you have?

[dart289]

i know yall moved on from it, but i am working on a solid state cooling suite. from small scale experiments i will say it definitely can work!

using a 8amp chip in 80F room i have been able to cool myself and reach 68f water (after 2 hours).
my new shipment got here yesterday. I'm going for 25 feet of silicone tubing for my suite.
the goal is to have a portable unit that can allow me to be outside doing light labor and feel like its a cool fall day

if anyone wants to compare notes feel free to ask.

[shellkamp]

I wonder if you could concentrate the actual cooling to parts of the body with large arteries/veins - such as the Wrists, thighs, or neck, then the body's circulatory system will do much of the work for you.

Sent from my SCH-I545 using Tapatalk

[dart289]

I did try that as well!

I had a all metal water block I put on the large vain to ur legs. I defiantly felt a little cooler but it was too intense for such a small area. also close to another sensitive area.

is that tubing in ur pocket? or are you just happy to see me?

wearing something on my wrists wouldn't be any good either, I don't work as a hvac tech but I'm sure u understand.

[HVAC_Marc]

Buy a Mini Cooper convertible with a/c and call it a day.

I have one. The roadster wasnt made after 2013. I think there are other larger versions of minis that have a retractable roof.

[Joel_Dude1450]

I'm going to guess it uses PAG oil. Should i vacuum it? should I heat the entire unit and then vacuum it? If i need to flush it, how do i flush the compressor?

That’s a water coil, not a refrigerant evaporator coil. What kind of metering device do you have?

I have a capillary tube, of " Capillary Copper Tube ID * L(mm): 0.6*2.5 " but I have since cut it shorter.

The evaporator is indeed a water coil, but its no different than a refrigerant coil, its positioned vertical, so the gas must flow upwards trough the coils. Its all i can get my hands on for now.

[Joel_Dude1450]

Hello everyone, I have an update:

So I managed to find the leak near the evaporator and now the system is tight. I also replaced the oil with ester, since other similar products use it too.

I made an extended run, and I added refrigerant until I thought it was good enough. These are the specs I'm able to get.

At Compressor MAX and Evap fan in medium air flow.
High side pressure= 1Mpa (145 psi), 43C~(109F)
High side out gas temp ( taken at end of dryer filter, where capillary begins) 100F

Low side pressure= 0.35Mpa (50.7 psi), 12C~(53f)
Low side out gas temp ( about 1 inch of pipe out of evap) 64.6F

Ambient air=82F
Air coming out of evap= 73~74.5F (Ignore heatsink next to Evap, it was not used to gather the data during the test)

I believe my capillary is too short, something is not right. Anyone care to help?









My Room is a mess I know...

[R123]

High side out gas temp ( taken at end of dryer filter, where capillary begins)???
Low aide out gas temp???

[Joel_Dude1450]

High side out gas temp ( taken at end of dryer filter, where capillary begins)???
Low aide out gas temp???

Well, if I'm not mistaken, to calculate "superheat" and "supercool" I have to measure these two temps. both coming in and out of evap and condenser, so that what I did. I began this project with 0 knowledge of A/C field so correct me if I'm wrong.

I took my info from here:
http://www.aprsupply.com/support/tec...-cooling-delta