Hey guys,

I've got a couple questions on system design and evaporator sizing for a liquid chiller project for engineering school.

Is it true that in designing a refrigeration system, especially when the evaporator stays at the process temperature when the compressor is not running, the evaporator should have enough volume to hold the entire refrigerant charge in liquid form, since that is where it will condense to when the system equalizes? The system will be a R-134a cap tube system and I plan on using a small 10 plate heat exchanger as the evaporator, which has approximately 5 oz liquid refrigerant capacity by my calculations. What happens if the required charge ends up being more than that 5 oz capacity?

Also, how does this all affect possible liquid slugging on compressor start up? I will be using hermetic reciprocating refrigerator compressors. Doesn't the suction return go straight into the compressor shell space, which means liquid refrigerant is highly unlikely to feed directly into the pump intake, making this a relative non issue so long as some reasonable liquid trap U bend is made in the suction tubing?

Another consideration I am up against is the choice of liquid line driers. I know the copper bullet driers are more or less useless for anything other than very clean, dry systems, but they also hold less liquid volume. I'd rather specify a sporlan catch-all, but would that also increase the required refrigerant charge?

Any insight is much appreciated!

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