TEC Chiller (Tiny Efficient Copeland)

[DetroitAC]

Sorry about the title, but this chiller is really in response to how many times I see threads with guys going to extreme lengths to build chillers out of TECs.

This is what I think a chiller should look like that cools to sub-ambient temperatures, but above the dewpoint. This chiller has a controller that activates a hot gas bypass valve when the system load is too low and the water will get too cool

What I have here is very simple, it's a Copeland 1/6hp condensing unit, High temp, R-134a, low starting torque. I think maybe this model condensing unit was recently made obsolete by Copeland, so there have been tons of them for sale on ebay. I bought some from ebay, I bought a few from Grainger since they stopped selling condensing units a while back and had these on clearance.

OK, also I'm using all new parts, although some are new old stock.

Sporlan balanced port TXV
Alco Hot Gas Bypass Valve
Alco solenoid valve, 115VAC coil
Two 1/2ton SLHXs for the evaporator
A way cheap Chinese PID controller, that using in on/off mode

I did a lot of work on this concept using just one SLHX, I tried using different size HGBVs, and figuring out the best way to build this. I did a lot of load testing with just one SLHX, before I decided that two is better (worth the added cost and complexity), especially since it will allow for fairly low flow rates, i.e. a current watercooling setup might not need to add an extra pump to deal with the chiller.

I've only done some quick tests with a configuration similar to what's pictured, but so far I can say:
@ 60F water deliver temperature, 2GPM flowrate, the cooling capacity should be ~490 Watts

@70F ~600 Watts

Total Power consumption will be ~300 Watts

The compressor always runs, and the controller and HGBV control capacity so that water temperature remains +/- maybe 2 degrees F to the setting on the controller.

I'm still not sure about a case, so the controller is just sitting on the worktable for now. I also need to make a bracket for the evaporator end of the vibration absorber in the suction line, and insulate, but I think what I've done will be easier to understand without insulation.

Next I'm going to insulate and start testing to get the true performance numbers.

[Sgrios]

Just beautiful DetroitAC, your craftsmanship is amazing.

[teyber]

jesus dude nice :O

how come two heat exchangers?

are you using the ebay PID controller? and is your solenoid a NC or NO?

[DetroitAC]

Two heat exchangers were more effective, I'm not sure of the numbers for increased effectiveness at all conditions, but at 2GPM it gives me about 20% more capacity. It actually makes the refrigerant side plumbing work out a little nicer, and it didn't make the overall size of the chiller bigger. Like I said I did a lot of testing with just one, but I think some guys might be running very restrictive systems with low water flowrate, so more effectiveness would be needed.

I think I bought them directly from Keling Inc, but they sell the same on ebay, and there are other way cheapies on ebay. FYI the one I'm using is relay output, the coil power is within the relay spec, so no external relay needed.

NC solenoid, which is what you want IMO, since if you size the chiller to be slightly greater than the load (maybe 110%), then you'll be activating the solenoid only a small fraction of time to control the load. Cooling capacity using the HGBV is adjustable, so I've tweaked it so that it goes to roughly 1/4 the capacity when the HGBV is on.

[[XC] gomeler]

I think the 2 heat exchangers are there to fully utilize the refrigerant. Perhaps at the flow rate he was using to achieve the capacity he wanted he needed additional surface area. Great looking build though, that is how a water chiller should be done

edit: beat me by a minute, XS should load new updates to threads while you type

[Plan.B]

Very nice build. I wish I had the skillz, tools, spare parts, etc. to build my own chiller. It's really the way to go. I stuck with the a/c convert or the ripped chiller from ebay...

[npk]

why not just a plate hx? top notch work

[wdrzal]

I like the "Quick change" compressor mounts !!!

[DetroitAC]

why not just a plate hx? top notch work

Most plate HX are not circuited well for refrigerant, they are a special order from Alfa Laval, Flat Plate, etc. Most of the cheapies on ebay are just single pass on both sides, special order of a tiny plate hx is big $$

These SLHX are corrugated for a lot of surface area, and I've been getting them new old stock for really cheap. They package better than a plate HX, and they work just fine.

OK, sorry, that's about 10 answers to your 1 question

@Walt- That's actually how Copeland was making these

[npk]

Most plate HX are not circuited well for refrigerant, they are a special order from Alfa Laval, Flat Plate, etc. Most of the cheapies on ebay are just single pass on both sides, special order of a tiny plate hx is big $$

These SLHX are corrugated for a lot of surface area, and I've been getting them new old stock for really cheap. They package better than a plate HX, and they work just fine.

OK, sorry, that's about 10 answers to your 1 question

@Walt- That's actually how Copeland was making these

that´s alright, knowledge is powa!

thanks for taking the time, I´ll be closely watching this one.

[teyber]

just a thought here...

frostbyte is in the stickies in this section... why not make this build in there too?

[Sgrios]

I second that. ^^

[npk]

do you think that cheapo controller would be good enough to use as temp controller in a chiller? (i.e. just on/off at the temperature set)

[Dualist]

That is very tidy work there Detroit, love it

[SNiiPE_DoGG]

Wow that makes me really really want to learn to build a chiller unit ..... too bad its so complicated and no where to learn or get tutorials...

[Xeon th MG Pony]

Damit, I was beaten to the punch again! Ah well I posponed the design by a year or two and I wasn't going to use HG Bipass, Looks good mate, I was going to use the higher inner volume for the evap and the nice thin side for water to gain max advantage of surface area.

[DetroitAC]

do you think that cheapo controller would be good enough to use as temp controller in a chiller? (i.e. just on/off at the temperature set)

I don't think so, a cycling compressor has a big current at startup, and even this tiny compressor would be over the limit while running. A commercial refrigeration low pressure control, or temperature control would be the way to go, they are designed to do just that.

@Dualist - Thanks, I didn't know you were still lurking here, long time no post, but it's nice to see you around.

@SNiiPE_DoGG - Just copy this one, although a chiller with a big res would be much easier in terms of controls.

@Xeon - Thanks, and I'm sorry about beating and punching you

[Jack]

Nicely done!

Just what I was looking for! I was wondering for some time now how to build a chiller without having to use a big reservoir. This build definitely seems to do the trick.

I think a plate HX would make the overall unit quite bulky. I like how it looks now

I still have a small ACC 3cc (1/12 hp) compressor lying around which might do the trick for a low power/low capacity chiller.

[teyber]

just gotta ask ya detroit- how come the bulb for the TEV is verticle? are some tevs made with verticle bulbs?

[DetroitAC]

just gotta ask ya detroit- how come the bulb for the TEV is verticle? are some tevs made with verticle bulbs?

Good question, the bulb is supposed to be mounted on a horizontal pipe run but I didn't have a good way to make the suction with a horizontal section, and still keep things compact. This arrangement is very compact, not much suction line, which is good for suction pressure drop. Basically, the spot I've got it is the best spot I could find.

IMO it's OK to violate some standard recommended practices, but when you do, you need to perform what engineers call due diligence (maybe lawyers too?). I need to test this unit well to make sure that my bulb location is OK. If I'd have been able to follow standard practices, it'd be almost a given that the bulb would work fine. In my testing so far, this location works just fine


Good question buddy, and I'd be happy to send you some copper tees if you need them.

@Jack, Thanks buddy, a 3cc would make a nice chiller, but that's so small, I'm not sure of a txv that would work

[teyber]

Good question, the bulb is supposed to be mounted on a horizontal pipe run but I didn't have a good way to make the suction with a horizontal section, and still keep things compact. This arrangement is very compact, not much suction line, which is good for suction pressure drop. Basically, the spot I've got it is the best spot I could find.

IMO it's OK to violate some standard recommended practices, but when you do, you need to perform what engineers call due diligence (maybe lawyers too?). I need to test this unit well to make sure that my bulb location is OK. If I'd have been able to follow standard practices, it'd be almost a given that the bulb would work fine. In my testing so far, this location works just fine


Good question buddy, and I'd be happy to send you some copper tees if you need them.

@Jack, Thanks buddy, a 3cc would make a nice chiller, but that's so small, I'm not sure of a txv that would work

ah thanks

Looks like i need to re-read the metering devices chapter of refrigeration and air conditioning

btw, YGPM on the t's

Thanks for quick and thorough response!

[Naja002]

Sweet. Very Sweet. Nice clean work. It's nice to see someone with your knowledge and experience putting effort toward an above-the-dewpoint build like this.... Not everyone wants to get as low as they can go. Some of us just want to chill out for the long-term.

Sweet and Thanx!

[DetroitAC]

Thx Naja

Some performance numbers with 2GPM water flow, the chiller is working at full capacity here, the HGBV is not activating (I set the setpoint to 40F):

Cooling Capacity (W), Power draw (W), Water Temperature (F)
700W, 326W, 77.5 F
600W, 315W, 70.5 F
500W, 301W, 60.5 F
400W, 277W, 51 F
300W, 271W, 46 F

That's about as cold as it would go unless I changed the fluid, but that's the "normal" working range for this chiller, 46F can still be below the dewpoint in the winter, but was only testing with water, so that's as low as I could go without building ice in the evap.

Next up, some testing with the HGBV controlling water temps with reduced loads.

[Naja002]

Apologies if this is a silly question, but: How do You determine the cooling capacity? Mathematically? Or is there a way to actually measure it?

[DetroitAC]

Good question, I'm measuring it. The last pic in the first post is my load tester loop. There's a Laing D5 vario pump (with my pump top ), load tester which is a 1200W tubular resistance heater, and a tee for bleeding. It's all kept as small as possible to minimize heat gain. I control the power input to the heater element with a variac, and measure the total power draw with a kill-a-watt. I have also done a little bit of flow testing to set the vario pump to produce only 2 GPM (had to set it to a little less than setting 3). I also have a kill-a-watt on the power cord to the chiller so that I can measure the total power draw by the chiller (compressor, fan, solenoid, controller).

So basically I set the load to a certain amount, and once the chiller has been running for ~30 to 45 min and temperatures stabilize we can say that the power input to the heater equals the cooling produced by the chiller.