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ASAD
03-01-2017, 05:28 PM
Hello,
I have to build a system for a room that will be used to check communication equipment.Room measurements 5X5X5Heat load- 2kw up to 40kwThe following conditions must be maintain in the roon:Temperature- (-10) up to (+50) celsius. Must maintain in any humidity.Relative humidity- 10% up to 90%. Must maintain at any temperature.Does anyone has experience with planning or executing a project like this? Any information or ideas will be helpful.Thank you

mbc
03-01-2017, 06:35 PM
Hi
may I ask
is it for lab.? or for test room ?
how you get the load.

ASAD
03-01-2017, 08:12 PM
Hi mbc
It is atest room
The load is from electric motors and.

The Viking
04-01-2017, 01:52 AM
I assume that the customer want to be able to maintain any given set point within your given parameters and not that the resultant temperature/humidity is allowed to fluctuate between those figures?

If so, the answer is: expensive...

Your best option would probably be multiple chilled water (Glycol) fancoils for the cooling in the room, sized to cope with your 40kW load + any loads from the room itself @-10C. The chilled water system fed by multiple chillers and with a decent size buffer tank.

For the humidity side of things you will need a dedicated humidifier as well as a dehumidifier, both selected to not give any additional heat gains. (Munters are normally quite good at giving advice on these type of humidity control issues.)

The ventilation requirements for the room also need to be considered and designed to cope with the requirements of the room otherwise the fresh air will upset your final results.

Not forgetting that walls/ceiling/floor needs to be insulated and vapour sealed.

But, before you start your design there are two important questions you have to ask your customer...
What stabilisation time and what tolerances do they expect? If anything less than 12hrs, +/-2K and +/- 10% then your best option is probably to walk away without even bidding for the job.

:cool:

ASAD
04-01-2017, 08:56 PM
Hi Viking
Thank you for the reply.
Here are some answers and some questions:
Yes I aim to maintain any given set points.
Why not to use dx systems?
What about using reheat to dry (at first)?
Stabilization time is 24 hrs.
Tolerances is +/-2K and +/- 10%.
Thank you again

The Viking
05-01-2017, 01:06 AM
OK,
DX dehumidifies a lot, if you aim to keep humidity of up to 90% this will be an issue. With chilled water (glycol), a buffer tank and multiple chillers the system will be easier to adapt to the varied load and dehumidify less as long as the chilled water temperature is controlled.
With the tolerances and control of both temp and humidity you are looking for my personal view is that you will need some sort of desiccant dehumidifier, this coupled with either cold steam or misting humidifiers. (You are looking at adding or removing about 6 litres of water going from one extreme of your parameters to the other) If you use reheat to dry then you either need grossly oversized cooling capacity or be willing to sacrifice control of the temperature. Remember, you might be asked to keep a humidity of 10% @ -10C.
:cool:

The Viking
05-01-2017, 01:22 AM
Let's expand on the chilled water thinking...

If your desired room temperature is -10C you can run your chillers to bring the buffer tank down to -20C but when the desired room temperature is 50C you can easily adjust the chillers' set point up to 30C and minimise dehumidification.
If your total load is 2kW for equipment and another 2kW for the room then you can just let a 5kW chiller take the load and when on the other hand they have 40kW worth of equipment in there you just let 4 of 10kW chillers and the 5kW one all work together. This would give both redundancy (apart from pipework) and energy efficiency.

:cool:

mbc
05-01-2017, 04:18 PM
Hi viking
thanks for very good explain we should read and learn from your replay

for one room we will have 5 units as you wrote and I think it is too many
2 units should be ok with 15% over plus

The Viking
05-01-2017, 04:50 PM
Thank you MBC,

The main benefit of multiple units is energy savings when there are great variations on the load, in this case from 2kW up to 40kW, not to mention redundancy.
If this system was split between 2 chillers you would have to start up a chiller with 23kW capacity to provide a duty of 2kW (+room load). Yes,it could be run this way providing there is a buffer tank large enough to allow the chiller to run without too short ON/OFF cycles but the running costs would increase. (not to mention that when 1 chiller fail you are left with only 23kW total cooling capacity.)

:cool:

mbc
05-01-2017, 06:57 PM
HI
The boffer tank is vary good idea
Because the temperature have huge difference and high side + 50 is to dengres for our suction pressure is to high
So the best idea is buffer tank
Thank's

ASAD
07-01-2017, 07:06 PM
Hi grizzly and Mbc
I am very respecting your knowledge and your experience. Here are my thoughts for now.


Despite what both of you wrote I do not see any advantage using chillers and buffer tank.

Generally I was thinking about five main systems and plc that will manage the process:

Cooling system- dx cooling systems (evaporator hanging inside of the room) with the possibility using inverter compressor in some of them.
Heating system - Heaters inside the evaporators.
Humidifier system - steam generators.
Dehumidifier system - desiccant dehumidifier with reheat in the cooling system.
Blowers system - for air circulation and for air exchange.

Thank you very much.

mbc
08-01-2017, 06:21 AM
Hi
If you going to use DX system inside room with inverter system for compressor you should use electronic DX
Also KVL and ...
So my belive you should use buffer tank with glicol
System
I did before it is easy way and safe to do this kind of work
You should choose your cooling system and then go further