Water Cooling

[Gina]

Gina that do look good for a hour, Do you think dry ice will work.

Yes, thank you I think dry ice would be difficult. I presume you mean instead ot the Peltier TEC. The idea is to keep the weight loading the focuser to a minimum and I think any dry ice solution would be heavy. Also, you don't want to freeze the sensor so you want some sort of control.

[Gina]

Hey Gina,

Haven't visited this thread for a bit, so just catching up. Wow, you've been busy

Results look good too. Told you water cooling would work

Just ensure that you get some coolant into the water once you get up and running and don't let the system freeze when not in use.

Cheers

Ian

Thank you Yes, I shall be putting some anti-freeze in the system when I've got it set up permanently.

[Gina]

maybe some offcuts of pipe lagging could help in the winter. the rad should be fine and the res but a little antifreeze would help. need to be careful with the copper block and silicon pipework.

this cam is sure going to beat down noise ratio's, cannot wait to see the end resulting images

Yes, as I said above I shall be adding anti-freeze in the final setup.

I shall, of course, post results when the weather permits me to see the stars and I've collected and processed the images.

[Gina]

Nice work Gina, that is certainly very impressive!! I take it the temperatures are repeatable? Did you do any work on a controller for the tec cooling? Or perhaps on the flow rate for the water or the fan on the heatsink?

Thank you Yes, the temperatures are repeatable. I haven't made the controller yet but have the design worked out. Currently, I'm just using a variable bench power supply. The pump is an aquarium water pump and runs directly off the mains - the only flow control is a slider on the bottom of the pump which, once set, is not really accessible as it's under water (submerged pump). I intend to use PWM control of the TEC to control the temperature using a power MOSFET. These have very low on resistance and generate little heat themselves.

[Gina]

The little radiator came this morning - much quicker than expected So I've now ordered a 120mm PC case fan for a couple of quid. Mind you the present system is working perfectly adequately.

[Mr TamiyaCowboy]

found a good read for you gina.

PC Water Coolant Chemistry – Part II | Overclockers

ignore the fact about cpu's and likes. but may want to add some antifreeze of some sort and anti corrosion, when running over the winter months.

[Gina]

found a good read for you gina.

PC Water Coolant Chemistry – Part II | Overclockers

ignore the fact about cpu's and likes. but may want to add some antifreeze of some sort and anti corrosion, when running over the winter months.

I have distilled water and antifreeze on order. From that article it seems dilute antifreeze is OK but will want extra corrosion inhibitor. Antifreeze at normal concentration for cars is too strong for PC cooling and this is much the save.

[Gina]

Now running with cooling TEC and fan running from 9v (rather than 12v) and EXIF T = -8C and getting a clear image. Now running 180s at ISO 1600 on M51.

[iwatkins]

[Gina]

Had to turn the volts down = EXIF T dropping too much. NOW at 7v and -8C. And changed to 300s At 800

[Gina]

A single sub just scaled for upload.

[Gina]

Well, the conditions weren't really as good as I thought last night and some haze came over. I managed to get just 17 lights of M51 and 3 darks before I shut down and went to bed. 5 mins subs at ISO 800. Results not as good as previously probably too few subs, though I do wonder if I got some condensation problems. I did let the temperature go down further than I had intended and it was a bit of a damp night - there was condensation all over the scopes and mount plus ice on the external part of the cold finger when I packed up.

[fatwoul]

I've been running cold water through my new Atik 4000 in order to reach -20C at my desk, whilst I build a darks library. I just bought a little external aquarium filter (£30) and a 14ltr Halfords 12V coolbox (£40). Drilled a couple of holes in the top of the coolbox, threaded 5mm aquarium airhose through and it works a treat. I get 3-5 degrees extra from it, which makes all the difference I need.

I've been in conversation with a guy called Rob at Watercooling UK, and we're trying to come up with a "proper" little 12V system I could install in the obsy. Looks like it will cost about £120 ish, which is a lot for only a few degrees of cooling, but it will be a lot safer than using water, and won't rely on cumbersome coolboxes.

Anyway, Rob seems to know what he's talking about as far as the cooling of electronic components. The biggest obstacle is selecting parts that don't light up bright blue or red and make your telescope look like a Subaru.

[Earl]

The biggest obstacle is selecting parts that don't light up bright blue or red and make your telescope look like a Subaru.

Blue it has to be blue blue is like... cool

[Reggie]

Gina, have you sorted out the icing problem yet? I was wondering when I saw yesyes gui for his TECs and saw that he had ambient dewpoint listed, it occurred to me that once you hit that, then you will have more of a chance of moisture being attracted to the sensor? I'm wondering what other ways you could mitigate that apart from sealing the unit? I guess airflow across the sensor is a bit of a no no?

Fatwoul, have you looked at xbox360/ps3 custom cooling solutions? They're designed to fit inside the meagre cases of ps3/360s might be an avenue to explore?

[Gina]

Gina, have you sorted out the icing problem yet? I was wondering when I saw yesyes gui for his TECs and saw that he had ambient dewpoint listed, it occurred to me that once you hit that, then you will have more of a chance of moisture being attracted to the sensor? I'm wondering what other ways you could mitigate that apart from sealing the unit? I guess airflow across the sensor is a bit of a no no?

I don't think blowing air from the environment over the sensor would help particularly on a damp night as dew would form on the sensor.

I've decided the easiest way of producing a sealed case for the camera is to use a plastic box to contain it and have sealed connectors for electrical and water connections and seal the front around the FR/FF housing. The latter will ensure that moisture can't get in through the light path. I shall then have desiccant inside to absorb any moisture present. I'm hoping that will take care of it. Details are in my Peltier TEC cooling thread.

I thought of circulating the air inside the box but a bit concerned about stirring up any dust that may have got in. Maybe a small very slow running fan might be alright - blowing or sucking air through the desiccant. With the box I'm getting there will be plenty of spare room inside. I was unable to find a box just a little bit bigger than the camera and don't feel like making my own though if the box turns out to look ridiculously big I may change my mind.

[ncjunk]

What would worry me with blowing air through desiccant is what flow rate would enable the desiccant to remove enough moisture?

i've only come across systems that are enclosed so the desiccant dries the air out over time...so no need to worry about what the rate of moisture removal of the desiccant is.

[Gina]

What would worry me with blowing air through desiccant is what flow rate would enable the desiccant to remove enough moisture?

i've only come across systems that are enclosed so the desiccant dries the air out over time...so no need to worry about what the rate of moisture removal of the desiccant is.

Ah - I see. Thank you So airflow wouldn't help then. Do you know what sort of time scale we're talking about for the moisture removal?

[ncjunk]

no idea, sorry. i am just thinking logically. Desiccant will have a specific absorbtion rate and in an enclosed environment it doesnt matter as you will leave it to do its magic. But in an open system you would want to ensure that sufficient moisture is removed from the air before entering the box...that just seems like it may be too difficult to calculate/control.

I have worked on only 2 hvac, air handling systems so i dont really have enough experience, but on those there is a large desiccant wheel on which the moisture condences. i then control temperature, flow, wheel speed etc to control humidity, temp and pressure, but importantly i have control and can vary each part of the system to achieve the required rate.

you've got me thinking though...do the silica beads have a rating indicating rate of absoption? is in temperature/humidity dependant? whats their capacity?

[ncjunk]

it does look like they can be used on compressed air systems.

so what quantity and what air flow rate would provide sufficient reduction in humidity? at this point my brain gives up