Coil Length calculation for de-humidifier

[gvkindia]

Hello,
I have just joined the forum in search of an advice.

We welcome an advice on the best choice for coil cfm ( optimum sizes) and velocity (fpm) and fin spacing ( fpi) for this de-humidifier.

The de-humidifier was fitted with the compressor rating:

BTU/Hr.: 1080 , KCal/Hr:272, Watts:316, Motor watts: 180, Amp:.086, Displacement: 6.15 cc/rev.,

Refrigerant: HFC-134a,
Ambient temp: 35 Deg.C ( 95 Deg.F),
Evaporating Temp: -6.7 Deg.C ( 20 Deg.F),
Condensing Temp: 130 Deg. C ( 54.4 Deg.F), Sub.Cooled Liquid Expansion:46.1 Deg.C ( 115 Deg.F),
Suction Pressure : 1.3 Kg/Cm2(18 Ps/g),
Discharge Pressure: 13.8Kg/Cm2 ( 196 pS/gm).

The de-humidifier is used in chyamber/room with the following ambient condition:
Temp max: 45 Deg. C ( the room has a halogen heater to heat the drying chamber/ room)
and RH: 85%.

the RH is to be maintained between 40%-50%
and
room size is : 10 ft x 6 ft x 7 ft( height)

......gvk

[Andy W]

Why do you need to maintain 40/50% humidity, is it a critical product?

I look after quite a few "drying chambers" but nothing with such small compressors, my chambers are approx 2.5m wide, 4 m long and 2m high. The dehumidifiers are custom made and are powered by a 5/6 hp compressor, either Bristol or Tecumseh and operate on R22, the coils are manufactured by beehive, the rooms operate at a temperature of 45oC and are equipped with 6 kw of electric heat, humidity is usually set at 10oC, there is a 2stage stat which controls electric heat and vent, once room reaches 47oC the vents open, one fan brings in air, the other fan draws air out and this is repeated through out the drying process. We use them for drying clay moulds for the pottery industry, drying out wooden pallets for the food sector and drying/curing gellotine based confectionary products. I have also used them on drying building blocks and carpets after been dyed.

[gvkindia]

Dear Andy,
The chamber houses food grains and food products made out to be dired.
The humidity is crtitical and need to be maintained at RH < 50%.
We need to design the sizes of Condenser and Evaporator coils and as well capillary tube sizes and length.
Regards,
Vijay

[TXiceman]

Anyone of a number of coil/unit cooler manufacturers can size a coil for your application. They will not want to give you information so that you can attempt to build it yourself. There is a lot of design work that goes into the air side as well as the circuiting on the tube side. WHile it is not rocket science, it is closely guarded.

Ken

[Andy W]

Beehive coils would be the people to speak to regarding coil building but as previously said, they would not design a system for you. Look up Calorex on the internet, they manufacture packaged dehumidifiers, I dont think your project is that difficult to do, the only problem I can see is a dehumidifier may achieve better than 40 - 50% so a humidifier may also be needed. Would it be a problem to achieve lower humidity levels, and regarding sizing capillaries, stick to an expansion valve and use a suction accumulator.

http://www.calorex.com

http://www.drycool.co.uk