household portable dehumidifier

[Lc_shi]

hi dear all
I will design a portable dehumidifier. The principle is not too difficult but I don't know what the critical tech for this product.
what kind of compressor for it? any special heat exchanger ?metering device? adjust for part load? welcome any suggestions for my initial work.


rgds
LC

[Andy W]

What is the point in designing or building a machine when they are so cheap to buy, in the uk I have seen them as low £55!

[Lc_shi]

it's too cheap. I wonder how to get profit for the manufacturer. how about the compressor? or the product can work without compressor?

rgds
LC

[botrous]

Hope this helps , below is attached a text from thr ashrea handbook cd .

Question for moderators , is it allowed to post articles from copyrighted materials as long as we mention the rights owner ?

Best regards

[Lc_shi]

Hi botrous
Thanks for your material.
I think it's no problem with the copyright because it's not used for commercial purpose.

rgds
LC

[botrous]

Welcome , hope it helped you . . .
As for the copyright i think you are right , i will check the forum rules to see what i can find , maybe the copyrights thing missed me when i read the rules when i joined

best regards

[botrous]

Hi Lichuan
It was great talking to you today , well i've done some reaserch and have builted a very good idea on the design of a dehumidifier that doesn't uses refrigeration cycle , using chemical products , well some time the product we need is just infront of us and we don't see it ....
It's the silica gel (used in refrigerant filters) , well there are other materials that can be used , some of them are liquid and the others solid , let me mention that the liquid are used as disinfectant to , so if the liquid is used the system will dehumidify the air and kill the bacteria as well ...
If you are still interrested in such systems let me know

cheers and best regards

[Peter_1]

We installed in the past some big dehumidifiers from Munters and DST.
I prefer Munters product but they're not cheap. Technology they use is very simple

[botrous]

I've read about the DST that uses silica gel rotors , it's a very good idea , the same design is published by the US departement of energy , and as their studies showed that using one of this desiccant dehumidifiers can improve the efficiency of the air conditioning system by 50% in some cases , that means that adding such kinds of dehumidifiers to the systems can enlarge the capacity of the systems,and the functioning coast of such system is low , what you usually pay for is the power used for the blower and the rotors , the heat used to make the silica gel renew is coming from wasted heat , the improvement of efficiency of the air conditioning system is due to that cooling low humidity air uses less energy than cooling high humidity air. (enthalpy of dry air is < of the humid air enthalpy )

Cheers and Best Regards

[Peter_1]

I even saw a Munters in a freezer to reduce moisture build-up on the evaporators.
They're also often used in ice-skating rinks to lower the RH preventing the steel construction from rusting.

I have a very small Munters for myself to use at home.

Lichuan, we can buy them here as Andy W said very cheap - well, actually never saw them at 55 £ and we sold more then 100 units the last 10 years - but they're all China made and works very well.
We had an add in the Yellow pages for some years under the section 'Dehumidification' and this gave us sometimes some special work and we also earned some money with renting these units. We then sold them afterwards as second hand.


We

[botrous]

Hi Peter , there is a broshure published by the US departement of energy in this link , more like a very small technical breif if someone is interrested .
http://www.eere.energy.gov/de/pdfs/t...umidifiers.pdf

Best regards

[Peter_1]

We still service some units for the Belgium Army and there are almost no spareparts in it.
It's only an electrical motor which runs the rotor via a belt, some very basic electrics inside and an electrical heating section and two fans.

[botrous]

Do you know what's the tempreture of the hot air that should strike the rotor in order to regenrate itself (i mean to release the moisture and become as new again)?

[Lc_shi]

thanks for all of your good ideas
the desiccant rotor is not good at small volume air flow,so it's not used in home at that time. But i'm not sure if it will be feasible as the tech develops. China has many manufactuers in this field,so it's a very demanding work to be better than the current ones. -

rgds
LC

[Peter_1]

Botrous, the temperature is as far as I can remember something around 130°C. Only a very small part of the rotor is covered and reheated.

Lichuan, keep it as simple as possible if you want to make one.

I can make some pictures of those we still keep here for spare parts but I think you've seen these units perhaps before.

[botrous]

Welcome Lichuan , hope those ideas were useful for you , as Peter said keep it simple . . . Hope it will be great success

Thanks for the information Peter , for me no need for picture , i've seen designs about it so no need for pics .

Best regards