Does these answer all of your questions?

Seresco | Dehumidifier specification and load calculation software ...

Dehumidifier Basics : ENERGY STAR

not really. I was looking for formulas and calculation software. none of them was solved

Then look at these:

http://www.way-technovation.com/Dehumidifier/calculat.htm#CALCULATING HUMIDITY LOAD
The Dehumidification Handbook - EI Solutions

I did not check out any of the posts, which likely work well, but another option is to get a copy of a psychometric chart- several sources available and likely via Google.

Just plot entering air condition- temp and RH and then desired leaving condition.

Follow horizontal line from each to right and read humidity load in units of weight per unit of air weight. 7000 grains of water equals one pound of water (or 0.455 Kg).

Weight of air at each point is also given by chart.

Just crunch the numbers.

To get a valid answer, you need to describe your project. If you are trying to dry out a sealed volume, then you only need to capture the excess moisture in the volume. If the volume is not sealed, you need to know the moisture ingress rate in order to properly size the dehumidification system. In other words, you need to calculate the amount of water you need to remove from the space per unit time to achieve the the desired water concentration in the space.

That is exactly what i am looking for- the moisture removal per unit time.

i just dont know what parameters i need to consider.

And for my project, it's a pharmaceutical tablet room which have to cool with a chiller and maintain a desired RH with a dehumidifier. Now i nee dto calculate the dehumidifier capacity. Please mention any valuable info that you think will be useful for this.I was specially looking for a software for this purpose with no success so far :(

Look here for software:

Humidity Control Calculations - Seresco

Sizing Industrial Dehumidifiers - Feature Articles - Process Cooling

Moisture load calculation - Seibu Giken DST

Please don't count on software to help you understand your problem or how to solve it. You need to know a few pieces of information before you can start any calculations. First you need to know the water vapor concentration required in your room. Then you need to know the actual water concentration that exists in your room. You then need to know the volume of your room. With these three pieces of data, you can calculate the volume of water you need to remove to obtain the required concentration. Then you will need to know the rate that water enters your room, from both external and internal sources. All this can be calculated using algebra - no rocket science required. The rest of the problem, like the most cost effective method to achieve the desired result, may take a bit of extra work. Make sure that when you deal in water concentration, you choose and use one measuring system. Air conditioning folks like to use lbs. of water per Million Cubic Feet at 60 deg.F and one Atmosphere