chill room drying

[ah fai]

Hello, please help

what can i do for drying the chilled room in 5 deg C and humidity at 60-70%

Thanks.

[Peter_1]

add heating or increase DT to 15K

[ah fai]

I need temp 5 degC and humidity at 50%, but now i get 5 degC at humidity 75%....

- if add heating will effect the room temp??
- u mean adjust the expansion valve to get suction at 15k
- what do u mean DT ?

[Peter_1]

Just install a small heater in front of the evaporator controlled by a humidistat. Switch it on as soon room temperature reaches its setpoint and use the switch over contact of the thermostat.
You can also split evaporator in 2 pieces if possible, 1/3 and 2/3 of the coil and then switch off 1/3 or 2/3 whgen lower humidity is needed.
15K is difference between evaporating temperature and room temperature.

[Magoo]

In Malaysia with high ambient wet buld conditions and humidity, acheiving 50% RH at +5.0'C is going to be difficult. You will need double air lock door entry and pre cooled air pressurization to limit ambient air in flow. Multiple evaps with low air flow and sequential cyclic air defrosts and after coil electric re heater banks as per Peter 1 suggestion.
I did several velvet ( those spikey things on deers heads )drier rooms with same RH condition, used cyclic hot gas defrost in evaps, and restricted air flow with small evap fans and had to add additional perferrated sheets of aluminium to air on face of coils to really reduce air flow. By reducing the RH the pressure differential was significant, drains and door seals etc., added bigger air balance ports with pre cooled air as well. Finally worked well after a lot of greif.

[chemi-cool]

you can add an independance air drier,
you can slow the air movement by replacing the fans.a small heater as Peter suggested is a good and common solution.