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  1. #14
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    Question
    What air are you trying to condition while on a motorcycle? For driver comfort at low speed?

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  3. #15
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    Just no embedded systems power electronics Cindy Wu / Shannon Liu spyware thing rofl

  4. #16
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    Interesting project. Wonder if you could develop enough CFM from an air compressor to use a vortex cooler? Then just pass the cool air into the rider's helmet.

    If you insist on using refrigeration technology, I would recommend making a mini air cooled chiller. Use a heat exchanger from the evap to a water solution, and add a small water pump.

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  6. #17
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    I thought about Vortex cooler but their COP is even less than Peltier. The fan will move about 150CFM to cool the condenser + any additional help while moving

    I dont want to use a chiller/water because it can leak, its heavy and probably more expensive to integrate in the design

  7. #18
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    Quote Originally Posted by Joel_Dude1450 View Post
    I dont want to use a chiller/water because it can leak, its heavy and probably more expensive to integrate in the design


    I think that's the least of your problems...

  8. #19
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    1. Yes: a short cap tube of small diameter can equal a long cap tube of larger diameter.

    2. Vehicle A/C systems are in the 3-4-5 ton range. Your palm-sized compressor is about 1/25 of one ton - so a restricter from a car is no where near to compatible.

    3. There may be some but I am not aware of any expansion valve as small as the compressor you presented as your choice.

    4. A variable speed compressor alters it's pumping capacity. All of the things you list are the result of compressor pumping capacity and will vary roughing in proportion.

    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
    -------------


    Quote Originally Posted by Joel_Dude1450 View Post
    I have a question I need help with, I was reading about expansion valves(XPV), Orifice tubes and capillary tubes:

    1)XPV: mechanical device controls flow of refrigerant with a bulb and diaphragm.
    2) Capillary tube: The smaller and longer, the more restriction.
    3) Orifice tube: Same as CapTube except these are small and short. Used for car a/c

    I was using some calculators online and they gave lengths of 3-6 meters for some capillary tubes, yet smaller ones where about 11 inches. A Orifice tube is a mere 3 inches long, the tube itself inside is like 1 inch long. A XPV is literally like 1 inch long.

    For this application, I'm guessing a maximum temperature for the liquid after the condenser to be 110F and I want the air going out of the evaporator to be 80F ( 75 if possible). The compressor runs about 2.8cc of displacement, capacity up to 500W cooling, I will use 134a. here is the compressor specs ( they are close to the one I want to buy)



    So here are my questions:
    1) Would a capillary tube of small diameter be the same as a long one with larger diameter? Is there a drawback to doing this( using a really small/short one)?
    2) Can I just use a orifice tube from a car? ( I suspect they are a capillary tube with very small diameter so its really short) I can modify them, or integrate them into the system)
    3) Is there any useful XPV that I can use for this application or should I avoid them? if I use a XPV do I need a receiver after the condenser?
    4) The compressor has variable speed. Can I use this speed control to control the head pressure/ condenser temps,/ cooling temp/ etc ( I guess its all related)

    I know that the answers might be vague or incomplete, since I dont have all the information now and they all depends on variables, but any help is greatly appreciated.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

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  10. #20
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    Too short or too long are not equivilant on cap tubes even thought mathematically they may be equivalent. Around 10' is a good choice with a HX
    8-12' total length is a good range to stay in.

    I'm with PHM
    unless you at planing some AC suit mini anything isn't going to cut it and anything big enough is going to cut gas mileage big time.

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  12. #21
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    Quote Originally Posted by Poodle Head Mikey View Post
    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
    -------------
    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.

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  14. #22
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    How bout a CO2 tank that unloads liquid into some kind of HX

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  16. #23
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    Quote Originally Posted by R123 View Post
    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

  17. #24
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    pretty damn cool.

  18. #25
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    Aug 2016
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    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.

  19. #26
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    Mar 2015
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    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.
    Last edited by Joel_Dude1450; 05-15-2018 at 04:54 PM. Reason: picture link empty

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