Container Freezer/Chiller advice needed

Discussion in 'Technical Repair' started by R!f@@, Jul 6, 2017.

  1. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Even though I have a specific member in mind, advice from all are welcome.:)

    @#12 I see from a AAC that you are an expert in Freezer and those kinda things.
    I am looking for advice and pointers.
    I need to relocate the outdoor unit of a container freezer and chiller unit. The freezer is at -15°C and chiller is at -8°C.
    Right now the out door is mounted at the base of the container. These are used to transport meat, fish and vegetables to resorts. They will be not stored for long periods but rather 2 to 3 days tops during transport.

    I need to relocate the outdoor from top deck to engine room. I can do the controller part without problems.
    My concern is the 50 foot distance that needs to be extended using copper tubing's.

    I can provide pictures.

    1. Would the temp be effected using such long distance ?
    2. What is the affect on the compressor using such long distance ?
    3. Is it OK to do so ?
    4. If temp is effected, how can I remedy it ?
     
  2. #12

    Expert

    Nov 30, 2010
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    Sorry. Been busy for a couple of days.

    The extra length of pipe is compensated by adding enough refrigerant to fill those pipes, whether they need gas or liquid. The ultimate rule is, "Check the pressures". If the refrigerant pressures are correct, you did it right. The larger the machine, the more accurate this method is. If you have some tiny machine that only needs 1 or 2 pounds, the accuracy gets bad with only a pressure measurement. For instance, my 24,000 BTU system wants the liquid refrigerant pressure exiting the condensor to be cooled below the condensing pressure by (Tambient, fahrenheit/10)+1
    That's enough pressure to get liquid refrigerant to the metering device with no bubbles in a low altitude land based system.
    The refrigerant exiting the cold coil must be sufficient volume to sustain the pressure at the output of the condensor, but that is controlled by the cold air flow and the metering valve. It is not within your ability to redesign that part so you just get the high pressure right and it should run.

    You have to take the refrigerant out to add more pipe, so you must be prepared to reclaim the refrigerant, install the pipes, vacuum out the bad air, and put the refrigerant back in, plus some.

    50 feet of pipe usually means very little to the compressor, but I could do the math based on vertical liquid column that has to be pumped up. It usually isn't significant in land based houses. Or is it hot gas going up? That would be insignificant in PSI per vertical foot.
    The very dangerous mistake is in failing to design for oil return to the compressor in the low pressure pipe. If half of your 50 feet is vertical, low pressure flow going up, you need to know how design for oil flow.

    This gets a lot more specific if you tell specs like, which refrigerant? What size in BTUs, tons, etc.
    Photos are certainly good because you don't seem to be fixating on the important points, like, "How much UP?" "Which flow is UP?" How much lateral?" "Can you guarantee that any lateral line with returning gas will be tilted downward toward the compressor?" "What diameter are the pipes?"
     
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  3. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    @#12 Thanks

    Info is so far very good.

    Vertical length is approximately 10 feet as far as I know. I dunno how to specify the length before so I just wrote down the total length.
    This work is being quoted, so if it gets approved I will give you more details. If it does not there is no point in continuing for the time being.

    I just wanted to know if the cooling will be changed cause the guy asked me that will it happen or not.
    I said nope.:D

    Seems I was right. :)
    But I will show you some pics once I get some time off. I am also very busy. I just get enough to glance at AAC.
    Just can't seem to ignore you guys.:p

    PS.. I know very little about charging and discharging gas, and all that. But I can get a guy who can do these things for me. I needed more advice from an expert so I will know what the tech is doing.
     
  4. #12

    Expert

    Nov 30, 2010
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    10 feet of, "up" won't require oil traps. If it did, they cost about $4 in pipe and an hour to fabricate on site.
    Horizontal length typically don't mean squat. It's real, it can be calculated, but the cost to the system is less than a percent in efficiency.
     
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  5. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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