Help choosing best danfoss compressor for single stage

[Stelios]

I'm new at Vapor Phase change cooling and right now trying to figure out what will best suit my needs.
My main concern is the compressor . The only sure thing is that i'm going to buy one of these :

http://compressors.danfoss.com/produ...z/s-series.htm

The candidates are : sc12cl , sc15cl , sc18cl and sc21cl

AFAIK the sc21cl is 3/4HP , the sc18cl is 5/8HP and the sc15cl is 1/2HP ...

Here's my questions :

I'm aiming at a full load of approx. 200-250W (Intel Prescott CPU) .

1) I want to calculate the efficiency of each compressor at 300W heatload . How's this possible ? Let's say for the sc18cl .
Are we looking at cecomaf or the ashrae numbers ? For 300W it can make approx -40celsius . But how much power consumption will it have ? The "Power consumption" and "current consumption" don't match ... What am i missing here ????

2) Looking at the specs , i see that Is that up to the sc12cl the current consumption scales up pretty good . From the sc15cl the current consumption scales up fast . Does this make the sc12cl the most economic compressor from the others when operating with the specific heat load ???

3) Let's see this from the hardcore overclockers point of view . What are the benefits from choosing the sc21cl from sc18cl ? It's about 3 degrees cooler and it has less power consumption . I'm i right ?

4) Can someone explain to me what the COP means ?? I understand that it is capacity/power consumption . Is this the efficiency ??? So , are we looking for the higher possible COP with our heat load ?

Thanks !

[wdrzal]

first,where are you located? are you aware you are looking at 220-240v @ 50 hertz compressors.

don't confuse the electrical load of the motor ,with the heat load of the compressor.

[Stelios]

I'm located in Greece , so 220V / 50Hz is for me .

[wdrzal]

COP= Coefficient of Performance. in basic terms This compares the heat/load capacity to the amount of electricity required to move it. refrigeration is simply moving energry from one place to another,it does not take 300 watts of electrial energy to move 300 watts of heat. This is where COP factors in.

[Stelios]

I searched in google and found that the parameter i need to know is the EER .

What about the question regarding 18cl and 21cl ? The price difference between these two models is 30Euros . Should i go for the 21cl or there is no point and also the electricity bill will be much higher ?

[wdrzal]

A compressor is just one componate of a cooling system.The entire system has to be considered before making a selection. You can not "cool by compressor" alone. there is a point that a larger compressor will not help the systems capicity,only hurt the wallet walt

[skate2snow]

For a normal single stage, single evap system, a 1/2 HP would be very good. But if in the futur you want to build a new system Dual Evap, or cascade, or something, a 3/4 would be great. But I would still recommend the 1/2 for the COP which walt sad previously...

[Russell_hq]

what you really need is volumetric efficiency proportional to pressure ratio for good design calculations. COP just doesn't cut it, but most manufacturers dont give this info

[hatemi]

I've made DD unit from SC12C and used SC18C in both stages of my cascade. They both are very nice compressors indeed but the SC18C migh be a tad overkill in a DD cooler

[Formann]

The compressors used in MachII is a NL11F 11ccm. With the right cap tupe length and charge it will do -45c load with the load from a NewCastle @ 3Ghz 1.8v or an FX55 @ 1.65v 3.15Ghz

The SC12CL is 12ccm, and should be marginally better. Which one to choose depends on what temps you are aming for.

For a nice SS cooler I would say the SC12CL is a good choice. SC18CL and SC21CL are overkill.

[Stelios]

The compressors used in MachII is a NL11F 11ccm. With the right cap tupe length and charge it will do -45c load with the load from a NewCastle @ 3Ghz 1.8v or an FX55 @ 1.65v 3.15Ghz

The SC12CL is 12ccm, and should be marginally better. Which one to choose depends on what temps you are aming for.

For a nice SS cooler I would say the SC12CL is a good choice. SC18CL and SC21CL are overkill.

-45c load on the CPU ? I think that it is difficult with the NL11F . Hipro5 uses the sc12cl and with his Prescott at 5G's he get's about -25c load on the CPU (with probe) . I think i have to take one more step and take something like the sc15cl or the sc18cl ...

Of course Prescotts dissipate a lot more watts than the A64's ...

[Stelios]

Let's say you have a small and a large displacement compressor and your heat load is 250W . Which one is going to be more energy efficient ? The small or the large ? Of course both can handle the heat load ... at different temperatures .
Will the larger one handle the heat load with more ease ?

[Formann]

-45c load on the CPU ? I think that it is difficult with the NL11F . Hipro5 uses the sc12cl and with his Prescott at 5G's he get's about -25c load on the CPU (with probe) . I think i have to take one more step and take something like the sc15cl or the sc18cl ...

Of course Prescotts dissipate a lot more watts than the A64's ...

-45c was evap temp. CPU temp I have no idea.

Both SC12 and SC15 will do just fine, but sc18 is overkill unless you are planning a dual evap cooler.

Im not sure about this, but I dont think a SC15 is that much better. -45c on evap with load is getting close to what a SS cooler can do without to much hassle.

[hatemi]

-45 with decent load with the prommy sized condencer is damn near impossible. The compressor might be able to keep ~200w @-30ish but that condenser is WAY undersized. With 10 degrees of superheat and subcooling and with 35c condencing temp the SC12CLX is rated to keep 200w around -35c with R404a.

[Formann]

-45 with decent load with the prommy sized condencer is damn near impossible. The compressor might be able to keep ~200w @-30ish but that condenser is WAY undersized. With 10 degrees of superheat and subcooling and with 35c condencing temp the SC12CLX is rated to keep 200w around -35c with R404a.

Im using a cheap thermometer, but when overklokk built the cooler he found that it was accurate within 2-3c @ -40c

The cooler is tuned for 100% load. Even 0.1-0.2v drop in vcore results in fluid returning to the compressor.

It took me 2 days to fint the excact right charge with r404/507 for the load my NewCastle puts out @ 1.8v 3.0Ghz.
With an FX55 @ 3.25Ghz 1.8v my thermometer was showing -39c

Of course the temps might be off by some degrees, but I´ll find out next week when I get my UEI 200.

[Stelios]

-45 with decent load with the prommy sized condencer is damn near impossible. The compressor might be able to keep ~200w @-30ish but that condenser is WAY undersized. With 10 degrees of superheat and subcooling and with 35c condencing temp the SC12CLX is rated to keep 200w around -35c with R404a.

I have a condenser from chilly1 which is bigger than the prommie one . Don't know exactly as i haven't got it yet from my friend who has it right now.

[Stelios]

Thanks for your answers ! ... I still have a lot of questions so i'm reading various refrigeration articles , guides etc ...

Dual evap is something i'm considering .

Monday i'm making my final decision ..

[hatemi]

That is the trick to get it hold loads charge it with massive load so it floods back if there isnt any load on it. Good for benching but not for 24/7 use I don't even see a point in using phase change in everyday rigs so I tune them acordingly

Im curently in the process of modding/fixing a prommie that had its suction line twisted too tightly. It now has another evap and 1m long 10mmID suctionhose in it but has alot of tweaking to it. I took the top of the casing of and I need to mount the case exit fan on the front of the condenser to help with airflow. I just need a way to get the fans running in turbo mode and start tweaking it. I have tested it once and with ~180w load the evap temp was -18c and rising and even the liquid line after the condenser was HOT!

[chilly1]

1) I want to calculate the efficiency of each compressor at 300W heatload . How's this possible ? Let's say for the sc18cl .
Are we looking at cecomaf or the ashrae numbers ? For 300W it can make approx -40celsius . But how much power consumption will it have ? The "Power consumption" and "current consumption" don't match ... What am i missing here ???? The Power consumption VS the Cooling capacity is the effeciency and is usually stated as COP {co-efficient of performance} s 1.1, 1.23 etc. so a compressor with a cop of 1.2 and power consumption of 235 will cool a load at rated temperature to 283 watts.

2) Looking at the specs , i see that Is that up to the sc12cl the current consumption scales up pretty good . From the sc15cl the current consumption goes up very quick. Does this make the sc12cl the most economic compressor from the others when operating with the specific heat load ??? Yes and NO you have to compare the same temperature ranges at multople points.

3) Let's see this from the hardcore overclockers point of view . What are the benefits from choosing the sc21cl from sc18cl ? It's about 3 degrees cooler and it has less power consumption . I'm i right ? I would use a sc10. the number in danfoss is the displacment dont get too big it will not make enough differance for a single stage.
4) Can someone explain to me what the COP means ?? I understand that it is capacity/power consumption . Is this the efficiency ??? So , are we looking for the higher possible COP with our heat load ? See above yes awe are lookng tofor higher efficiencies. I have a 1/4 hp that has a LRA of 10 it will remove 163 watts art its rated evap temp of -20C with r123a With R402 it will remove 285 watts at -38C.
Thanks