10 replies to this topic

[Maxim]

Hello everyone!

Firstly id like to thank everyone who put their efforts into organising AGM last night, it was a great experience and i met some very talented people!

My problem is, is that ive made my own star dryer using a 50L plastic box and a mini dehumidifier.

I put the small boxes full of stars inside the plastic box, put the dehumidifier on and then closed the lid of the box which pretty much seals it. However after a week the stars seem still pretty damp. Moreover i have noticed that there is quite a lot of condensation on the bottom of the inside of the box and small amounts by the lid. Because the UK isn't the best for sunny weather, i don't have any other option for drying stars and wondered if anyone could help me.

P.S. i am aware of the other star dryer topic but unfortunately i would not be able to build one as i've spent way too much on chemicals and other equipment already!

Thanks!

[phildunford]

Hi Maxim,

Hard to say without seeing a layout of your design...

The important thing is to get a flow of air - that's what takes away the water vapour. No harm in a bit of bottom heat too.

Stars are probably best on wire trays so that the air can get all round them.

Mine is just a box with a (covered) 20W bulb in the bottom and a computer fan in the top. The warm air is drawn up through the trays of stars through holes in the bottom and out of the top.

Stars not bigger than about 9mm should really be dry on their own in the UK in about a week or so unless they are a very difficult formula.

[Maxim]

Hey Phil, i am the curious one about your star rolling machine at the AGM if you remember

I shall post a few pictures shortly to show you. What i can can tell you is that there is definitely no flow of air and the star are not on wires...

[Arthur Brown]

You say "dehumidifier" do you mean a chemical adsorbant (silica get or the like) or something with a drain. A 100g of powder when first made into stars may contain 12 - 25g of water. now that may be beyond the capacity of a silica gel type unit, refresh it and start again!

[rocketpro]

Hello everyone!

Firstly id like to thank everyone who put their efforts into organising AGM last night, it was a great experience and i met some very talented people!

My problem is, is that ive made my own star dryer using a 50L plastic box and a mini dehumidifier.

I put the small boxes full of stars inside the plastic box, put the dehumidifier on and then closed the lid of the box which pretty much seals it. However after a week the stars seem still pretty damp. Moreover i have noticed that there is quite a lot of condensation on the bottom of the inside of the box and small amounts by the lid. Because the UK isn't the best for sunny weather, i don't have any other option for drying stars and wondered if anyone could help me.

P.S. i am aware of the other star dryer topic but unfortunately i would not be able to build one as i've spent way too much on chemicals and other equipment already!

Thanks!

I`m no expert on this subject, but could it be that because the de-humidifier is enclosed within the box, it`s just recirculating the water vapour?

[phildunford]

Hey Phil, i am the curious one about your star rolling machine at the AGM if you remember

I shall post a few pictures shortly to show you. What i can can tell you is that there is definitely no flow of air and the star are not on wires...

Hi Maxim - thought it might be you. One thing that went pear shaped on the day was name badges, so I did not get as many names as I would have liked...

I will put up the circuits of the speed controller and the firing box, but it's a bit hectic at the moment - now the AGM is over I'm involved with the Joyce Green recovery.

[Maxim]

The dehumidifier is an electrical moisture extraction and condenser unit i.e. it takes in air, takes out the water vapour and condenses it and then that water is stored in a removable tank and the air is then let out at the other end, posting pics in 2 mins.

[helix]

It probably wont work if youve enclosed the dehumidifier in a small space. A dehumidifier has the same components within it as a fridge, it dehumidifies the air by blowing it over a cool coil, which operates at a temperature below the dew point of the air. Basically the dehumidifier needs to get rid of the heat that it removes from the cooling coil, if it can't do this effectivley then your enclosure will get hot and the cooling effect which does the dehumidifying stops.

You could either allow some air flow though the enclosure to reduce the heat build up and see if this works or try and get the hot bit (condenser) of the dehumidifier to reject its heat outwith the enclosure somehow.

Hope this makes sense.

James

[Maxim]

Apologies for the really bad stars, they were a failed hand roll attempt.

Edited by Maxim, 28 March 2010 - 08:51 PM.

[starseeker]

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I think the only way you could get this to work is to have the dehumidifier on the outside and to build a duct to connect it to the drying box,then it will exhaust to the open air.

[digger]

Ok I have built dehumidifier dryers before now and they work great.

The one thing that jumps out at me is the lack of space and the arrangement of the stars. What you need to do is ensure that the dry air from the dehumidifier blows past the stars, for this it is best to use a mesh screen.

check out this thread Clicky Clicky. The cab shown has the dryer at the bottom right. The top has been modified since the picture to allow the air to flow from the right side to the left side in a circulating motion. I use it for drying all sorts of things from wet chemicals after synthesis to glass ware and mixing bowls. It is a great labour saving device.

P.S. if it is a "proper" dehumidifier and not just a peltier cell, do not exhaust the air as you will achieve much lower relative humidities (dew points) by recirculating the air. You will also get less of a heat build up because the condensation of water increases the air temperature. So as the stars dry less energy is released due to the thermodynamics of the system (Carnot cycle). You should find that the cabinet will run about 10C - 15C above ambient temperature if sized correctly.

Edit for punctuation (will need doing again)

Edited by digger, 30 March 2010 - 07:49 PM.