And now for something a bit different.

[sacha35]

This is my latest project, it’s a lot bigger and much more different than the normal units we all see, My thinking behind it was to have two condensers with the 93cfm fans blowing from either side to try and keep the compressor and gass nice and cool as you will see I have made a small SLHX and hope to have the unit running a mixture of R402a and R410a which will make things run that bit hotter than normal.

The unit is not finished yet as I am still awaiting Chilly1’s new evap, once this has been fitted and pressure tested I will then do some more paintwork to the compressor and some pipe work.

As you will see i have made two trunking compartments for all the cabling, one section for 240v and another for data and ELV cables, the system is fully protected to 16th edition wireing regs has thermal and overcurrent protection,it also has a safty presuer cutoff switch incase the presuer gets above the set limit.

A Big thanks to SoddemFX for all his input and help

Anyway that’s enough waffle hears some pics.




















Sacha

[{.bLanK} GoD]

Very clean.
I think I like it
I'm looking forward to seeing some results.

[Brettbeck]

Yeah very clean . How long did you spend cleaning the brazed joints hehe ?

So is it basicly a single stage? The design seems a bit confusing . Or maybe it's just me (just woke up). I will read it again later see if I can make more sense lol .

[aasmaukr]

Good-looking

[LittleDevil]

Nice project

Regards

[jimmsch]

Love the case. Too bad it is so....HUGE! Looks great though.

[sacha35]

Thanks for your coments Guys, yes this is one big case,big enough to build a small cascade, but as said this unit will be running hot so i wanted to have plenty of space for cooling and to be able to enclose all cables and control gear in protective trunking, as you see i have two condensers to increase the volume and also the way i have laid this out at 45 degree angle will allow the two 93cfm fans to cool the refrigerant and hopfully keep the compressor nice and cool.

Sacha

[Marvin]

nice case. I like the condensers displacemant too.
Looks like a shark

[Clemmaster]

Very nice work, like mc donald : "I'm lovin' it" .

Just 2 comments :

- You should have made the HP a bit longer (rolled up) because compressors sometimes strongly vibrate on start up.
- I deffinetly don't understand why you're still obstinated with SLHX :| . If you check the design features you'll see that this compressor isn't able to carry any big load under -45° (holds sth like 100w under -35° :/) and trying to reduce the LP won't help it to do its work properly as you reduce in the same time the flow...

[sacha35]

Very nice work, like mc donald : "I'm lovin' it" .

Just 2 comments :

- You should have made the HP a bit longer (rolled up) because compressors sometimes strongly vibrate on start up.
- I deffinetly don't understand why your still obstinated with SLHX :| . If you check the design features you'll see that this compressor isn't able to carry any big load under -45° (holds sth like 100w under -35° :/) and trying to reduce the LP won't help it to do its work properly as you reduce in the same time the flow...

Hi there thanks for your coments, i am just trying this compressor out first to see how well or not it works with this setup, as you see there is loads of room so i could easy fit a nice SC18 in there which should be more than big enough for this setup to work.

As for a desuperheat coil i have opted to not have one as this would increase the capacity even more, to get over the vibration the condensors will be mounted on rubber mounts so this should take up any vibration as both the compressor and condensors will both be able to move when the comprssor is starting and running.

Thanks again for your active coments though.

Sacha

[Clemmaster]

I think it won't be enough because I suppose they will be attached by the feet?! When the unit starts (not every time, juste sometimes, I don't know exactly why but I think it depends to the position of the piston....) it "jumps ahead" and even if they're attached compressor will "compress" the pipe :p


About SLHX's : It's not because someone uses it on his systems that you have to make the same on every one : It's useless when you haven't got a powerfull compressor, able to carry much more load than ever requiered by the systems : You use a part of the power to help gas being condensed at lower pressure and so the unit is able to work at some "pressure" it's not designed for. Keep in mind that the power of the compressor don't make everything : If you compare the danfoss nl11f and SC10G (both 1/3hp) you'll be surprised by the capability of these 2 compressors :

- Danfoss NL11F is able to carry 105w under -35°
- Danfoss SC10G isn't able to carry more than 23w under the same temperature xD

Both are using the same gas, R134a, condensing at 55°.

Another exemple :



on the left : Danfoss SC18CL
on the right : Danfoss SC18G

Both are 500w compressors, one runs with R134a condensing at 55° (G), the other one with R404a condensing at 45° (CL). The SC18CL works at even worse conditions (the high pressure is higher).

[n00b 0f l337]

We run these so out of spec, many people have gotten -40C with 200 watts of load. Look at little devils builds.

[Clemmaster]

I know that, the condensing temperature isn't as high as in the CECOMAF certifications, I've gotten the same too but if you look at the temp reached : -40° : there's no need to add any SLHX to reach theses temperatures as the R404a, R402a, R507c... is still around 1bar BP

[Dimas]

nice case...and buld too, waiting for temps

[sacha35]

I think it won't be enough because I suppose they will be attached by the feet?! When the unit starts (not every time, juste sometimes, I don't know exactly why but I think it depends to the position of the piston....) it "jumps ahead" and even if they're attached compressor will "compress" the pipe :p


About SLHX's : It's not because someone uses it on his systems that you have to make the same on every one : It's useless when you haven't got a powerfull compressor, able to carry much more load than ever requiered by the systems : You use a part of the power to help gas being condensed at lower pressure and so the unit is able to work at some "pressure" it's not designed for. Keep in mind that the power of the compressor don't make everything : If you compare the danfoss nl11f and SC10G (both 1/3hp) you'll be surprised by the capability of these 2 compressors :

- Danfoss NL11F is able to carry 105w under -35°
- Danfoss SC10G isn't able to carry more than 23w under the same temperature xD

Both are using the same gas, R134a, condensing at 55°.

Another exemple :



on the left : Danfoss SC18CL
on the right : Danfoss SC18G

Both are 500w compressors, one runs with R134a condensing at 55° (G), the other one with R404a condensing at 45° (CL). The SC18CL works at even worse conditions (the high pressure is higher).

I think you are referring to the Transient starting phase angle, yes this would have a big impact if the condensers were mounted to something rigged, but as explained they will be able to move with the compressor as they will be mounted on rubber mounts from the back plate thus allowing up/down and sideways movement.

I take what you are saying with regards the SLHX and I think you have seen where some have good and bad results with them, if this proves to be problematic then it will not be a big job to remove this and connect in conventional way, but saying this, this is why we try and push the boundaries of phase change seeing what gasses and compressors can do under different conditions, this is how we learn about the cause and effect of things that are happening.
As n00b 0f l337 said we run these so out of spec, many people have gotten -40C with 200 watts of load. Look at little devils builds, this is why we try different things, and some work and some don’t.
sacha

[Pete]

Really nice dude. Has some very very high tech but also arty feel to it and more! I like the idea of the airflow being directed at the side of it.

Can you tell me how you got your gauges to stay in place? If you have any photos of that PM them over saves spaming your topic.

Hope it all goes okay dude

Pete

[sacha35]

Hi there pete, thanks for the coments, they are just ashcroft Gauges with a u Clamp bracket to hold them in, you can see this in the photos posted.
Link:
http://www.ashcroft.com/products.cfm?doc_id=192

[Pete]

Hi there pete, thanks for the coments, they are just ashcroft Gauges with a u Clamp bracket to hold them in, you can see this in the photos posted.
Link:
http://www.ashcroft.com/products.cfm?doc_id=192

So the bracket stop it from moving ether way...umm looks like i'm going to steal that idea for mounting the ones in my rig. Guess just make the plate and use a nut to hold it in place

[andybg]

Looks good but that ferrule on the suction tap has to piss you off .

[Clemmaster]

Clemmaster,

First you're comparing two compressors opperating at approx 0.7bar suction with r134a (not realistic) the two compressors having displacements of 10.3cc and 11.2cc

Instinctivly the NL11 will be the better compressor due to the higher displacement and it does perform better than the SC10. As the evaporating temperature rises the SC10 does pull back against the NL11 and at higher suction pressures the capacity differences become that of the displacement difference.

The reason is the SC range don't do so well in LBP opperation, but you can't get the NL series with 18cc of displacement either...

With the second comparison you cant compare them like that, you're running two different refrigerants. To be honest wether a compressor is rated at 1/3IHP or 12000BTU's or 500W is fairly irrelevant for us as we're not evaporating, condensing at the pressures or in most cases even running the manufactures specified refrigerant.

All that matters for us is the displacement, rpm, efficiency (in our conditions) and wether the motor is capable of running under the loads we subject it to.

The idea of a SLHX being used to transfer sensible heat from the gas state refrigerant into the liquid line to decrease enthlapy of the liquid refrigerant, at the expense of suction line gas density is not the main point with this, it's a nice side effect at best.

The idea is that as the swing in load can be very large. Without using a true suction line accumulator there needs to be some means of evaporating the return liquid under idle conditions, this is provided by the small SLHX which will provide this energy from the warm liquid but also via conduction from the condensors.

When the system is under full load the gas heat exchange from 10" of 1/4" inside 1/2" will be small and hopefully not have too much of an effect on suction gas density. As the system is capillary tube regulated the superheat under full load will already be high, but the aim is that by using this SLHX the full load superheat can be decreased by increasing the systems charge, the SLHX preventing liquid return under idle.

Manufacturers data isn't very usefull when you have 20% less suction gas density under full load.

Tom

Displacement doesn't justify such difference between the to compressors. You can compare the SC12G that is a 1/2hp with 12.9cm^3 displacement compressor to the nl11f as you please and you'll see that the first one isn't able to carry more than 65w compared to the 100w the nl11f is able to carry with only 1/3hp and 11.2cm^3 displacement. both tested with in the same conditions. So That confirm what I'm saying : the power doesn't mean anything itself.

About gases : I've made simulation with Coolpack and if you set the condensing pressure and evaporating temperature, results are almost similar between R134a and R404a : one has got an higher "volume throughput" (don't know how to say in english ) and a lower density (R134a), and the reverse for R404a : they compensate each other. Only true limit may be that the motor is "speed-limited".
Unfortunatelly there is no documentation about the SC18B that is a SC18CL running with R134a and that we can compare to the SC18G, i've got one and I can affirm that they're performing better in LBP than SCxxG do (I had got 1 SCxxG and SCxxB and I've seen the difference between them two : the SC18B is able to carry my waterchiller evap under -50°, the SC10G wasn't able to freeze completely an smaler one under -30° :/ (without any load of course).


About SLHX's now : it actually decrease enthalpy and they're useless on nl11F-designed system as This compressor isn't designed to work at such pressures. The only thing I find good si that by decreasing HighSide pressure and increasing a bit the vapor density you descrease the Pressure ratio and that's a good point for compressors that perform at best with a ratio around 6. You just reach lower evaporating temperature but once loaded if you still want it to make effect you've got to charge more gas and then the effects that goes with.

Warning, I'm not saying that they are useless on every systems, with big compressors that are able to carry lot more than enough at low pressure it helps him to work at even lower pressure. A rotary with R410A and SLHX may be the best using

Edit : round 2

[Barnsley-Bill]

Looks realy nice sacha35 very clean and pro looking once again love to see how it gose mate .

[sacha35]

Looks realy nice sacha35 very clean and pro looking once again love to see how it gose mate .

Just awating Chillys new evap kit, which i should have by the end of next week, then it will be all systems go with tuning and testing and tuning.

[{.bLanK} GoD]

And more testing and tuning :P lol
Good luck dude.
Have you pressure tested what you have done so far?

[sacha35]

Thanks there {.blank} God, yes some pressure testing has been done and all is ok so far, so when i have the evap it will just mean testing this then brazing it all together and retesting the whole thing, and then like you said And more testing and tuning :P lol

[Clemmaster]

I've just read what you're saying and I realize that we agree each other. When I compare SC18 angainst SC10 I know that there is an enormous power difference between them but I know how the system would perform if there where the same power (as I runned them without any load, even if it takes more time to freeze with the SC10G) : I just compare SCxxCL/B against SCxxG and I'm sure that the CL or CLX do perform very well in vaccum (they're designed that for...), and a SCxxG may like "pushing". SC18B is LBP designed compressor, like the SC18CL. All I want to say is tht most of phase-change make don't really know what they're building their systems with, they just do compare 2 compressors with their "power rating", they're not looking at the pressures they are designed for and that's why some of them don't understand why, for example, the nl11f can carry such load.


About SLHX's I think we agree to that most of them are fully oversized and they are not playing the role they're supposed to play because system must be overcharged to freeze it entire and it becomes finally useless.

When I say ratio 6 I know that we are running out of this, and on well-powered system I may reduce the ratio a bit . What would be interesting to test is the serial compressors single stage unit. A LBP compressor such as nl11f do vaccum work, compress a bit the gas around 3-4bar (to reach ratio 6-8) and a MBP compressor compress the gas again and works in the pressures it's designed for : >2.4bar at succion line and a High pressure around 16bar. It may work wery well with R410A, I know that's used in the industry and I don't know if anybody has ever done the same.