Hi, fourth year mech engineering student and this is the first time I've waded into practical refrigeration engineering.
I'm trying to build a glycol chiller for a home chemistry lab. I've managed to find a "broken" portable air conditioner (I suspect the previous owner didn't know how to use it) that I'm looking at modifying for the task. The cooling capacity is supposed to be 2640 watts at 930 watts input power.
It's got a 44A233A compressor using R-410a in it. I've managed to find a datasheet for the compressor that says the evaporating temperature range is -10 to 15C and also has power, capacity and flow rate to evaporating temp graphs but those only extend to 0C.
I'm hoping to get some advice as to how well this might work if I push it much lower. I was hoping to get to -30C. Thought not in any datasheet I could find, the nameplate on the whole unit gives 0.8MPa to 3.2MPa which I assume is for normal operation as an aircon unit. Looking at some charts, for -10C as in the datasheet, the low side pressure should be ~470kPa. -30C would be ~130kPa.
What sort of compressor issues might I see at that pressure? I dumped the 0C to 12C data into excel and then used a trend line to estimate the flow rates down to -40C which gave me about 15kg/hr flow rate at -30C (compared to ~40 kg/h at 0C). My thought was the trendline would be reasonably accurate assuming the condenser keeps condensing (it's quite large, fan forced and room temp will be <25C)
As it was basically free I'm not too worried about breaking it or its reduced lifespan, but I would like some advice as to if this is even possible. My understanding is that with it's higher pressure at low temperatures, R-410a should be very suitable for low temp use, but it doesn't seem to get used, which makes me think I'm missing something here.
Advice?
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