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Author Topic: DIY water chiller - reading suggestions?  (Read 12290 times)

BruceM

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Re: DIY water chiller - reading suggestions?
« Reply #180 on: September 18, 2021, 11:35:00 PM »
Ha!  Bad headache today but maybe tomorrow I'll evacuate then charge and give the Emmerson a go.

BruceM

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Re: DIY water chiller - reading suggestions?
« Reply #181 on: September 25, 2021, 11:38:05 PM »
I took out the TXV that can't be adjusted without evacuating the system, and put in a needle valve plus the cap tube.
That let me restrict flow as temperatures climb to keep a constant 4.6 amps.

I tried wood then a metal cover for the condenser coil to restrict airflow so I could simulate a hotter day. The leaky stack of lumber gave better results; the metal cover seemed to cause greatly elevated current for the same temperature. Something about too much of the coil not being cooled at all.  The metal cover is shown in the picture.

As liquid line temperature got above about 95F, the BTU perfomance starts to fall off rapidly.  I'm able to get 13.6K BTU's at 90F,  13.0K at 94F, 10K BTUs at 102F.   Then it falls on it's face, and there's no chance of it not being adjusted properly, since I was doing it manually while watching compressor current, every so slowly.

So evaporative precooling is a must; my former LG window unit doesn't have the advertised 12000 BTUs, EER of 11.3 at 95F ambient at my elevation, at least.  (95F would be 110F liquid line temp at 15F approach).  I'm not getting anywhere near this performance at 95F equivalent liquid line temps.  More like 4000 BTUs.

I can likely live with the needle valve/cap tube combo, but could get the best cooling performance with an electronic expansion valve and custom microcontroller programmed to adjust for max rated amps.  They are cheap, but no one but me could maintain it or appreciate it. 


« Last Edit: September 26, 2021, 04:03:03 PM by BruceM »

BruceM

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Re: DIY water chiller - reading suggestions?
« Reply #182 on: September 27, 2021, 12:58:33 AM »
This afternoon I picked up the bargain bigger brother of my 12K BTU LG; the 18K BTU model from a nearby seller on Craigslist.

It has a bum evaporator side blower wheel, that is making some slight noise, and was pretty dirty, thus the new bargain price of $150.  I'd been watching it for a few weeks.

I ran it before taking it apart for a good cleaning and inspection; it draws 1600 watts while running the blower on high.  The compressor sounds good and the air was cool.  The total unit and the condenser seem huge compared to my 12K unit.  The fan motor on the 18K unit  is 276W instead of only 80W for the 12K unit.  One option is to use the 12K compressor on this chassis, with it's much larger fan and condenser coil.  The fan will have extra power for the evap cooling without a supplemental fan.

The question in my mind is if I reduce the power via cap tube/needle valve combo, can I still get good BTU levels.  Even more interesting would be if I can get acceptable performance at higher temperatures without adding an evaporative pre-cooler. 

I was surprised that this unit has an LG compressor, made in Korea. 

I just couldn't resist it for $150. 









BruceM

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Re: DIY water chiller
« Reply #183 on: September 07, 2022, 11:06:00 PM »
An update:
I built an insulated tower for air intake at 6 foot for cooler air (10F hotter than ambient here near the groundin still air from sun heating of the earth), and an evaporative pre-cooler.  The precooler is just a single aspen pad, with a standard 230VAC evap cooler pump (70W).  I upgraded to a new (surplus on ebay) Panasonic 1350W compressor after finding that the used LG compressor had starting problems, and lousy performance at higher current draw. 

I added an Arduino nano, power monitor via I2C, 6 Dallas one wire temperature sensors, and a 4x20 character LCD display, and a stepper motor driver board for a Chinese EEV.  I also got a larger brazed plate heat exchanger, and increased my water flow rate from 2 GPM to 3.2GPM with a Lang D5 12V pump.

It now cranks out 15-17K BTU (10 degrees of cooling at 3.2GPM) on 1400W to total power (320 of those watts for fan and water pump), the compressor is loafing and runs at only 115F on the top of its case. 

The one area that needs work still is that even going to a larger EEV I have found that my filter dryer seems to be restricting flow enough that there is no change from opening beyond half way.  That's an easy fix problem but today I just wanted to take advantage of the heat and give it a long shake down run.

As I write I am now (ever so slowly) cooling my house while its about 95F outside, on my solar PV/inverter system.  Its been a very educational project.

Evaporative pre-cooling makes for a near doubling of performance at the same power level on hot days in the high desert.

PS-  The line of temperatures on the display are:  Incoming air, cooled air,  HP refrigerant line,  Suction refrigerant line, Water into BPHE,  Water out of BPHE.  The dT and KB (K Btus) are full accuracy.  EEV position is 300.  Ill try to find and add one more photo.  The difference between the displayed watts and volts times amps is due to power factor.  An inverter must provide the full VA, not just the "real" watts so I should change my display to that.

PPS- The Control box with Arduino Nano is squeezed in next to my propane (backup) water heater.  I used all standard drivers for the power and temperature monitoring. The Dallas One wire software is very slow, about 1.5 seconds for updating all 6 sensors plus a bit of floating point math for that and the power monitor board but that's OK.  Right now I have manual switches as inputs to the Arduino for controlling the EEV and power relays. By next summer, it will be automated.  Te perf board left of the Arduino is just a 5V linear regulator and an analog circuit that senses water flow rate and shuts down the compressor power immediately if flow rate drops below 2 GPM; that assures no water freezing and the resulting wrecking of the heat exchanger.






« Last Edit: September 07, 2022, 11:42:56 PM by BruceM »

32 coupe

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Re: DIY water chiller - reading suggestions?
« Reply #184 on: September 08, 2022, 01:59:39 AM »
As Clint Eastwood would say in a low tone voice...."Oh, yea"....

Bruce,
Looks amazing. I'm glad you got it going !


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BruceM

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Re: DIY water chiller - reading suggestions?
« Reply #185 on: September 08, 2022, 04:36:42 PM »
Thanks!