You are probably wondering what I mean, and I don't blame you with such a title :). So let me ask you a question - if we design a completely air-conditioned system, i.e. an air conditioning unit that is intended to provide full air conditioning for the rooms, can you choose the proper air flow for air conditioning? Regardless of the answer, I invite you to read the article as it can significantly simplify your work. Moving on to the point - what is most important in determining the required air conditioning air flow? - of course, the heat and humidity gain balance. To do this, I personally use the Teknosim 2000 program from Lindab, because I have control over all room parameters, and I use this program mainly to calculate dry heat gains through partitions and to take into account gains from lighting and possibly equipment. I calculate heat gains from people or other sources, such as water surfaces, in the IX-CHART program.

So with Teknosim 2000, I have a balance of dry heat gains, and with IX CHART, a balance of dry and wet heat gains and humidity. By adding the dry and wet heat gains, we get the total heat gain balance, which is the basis for determining the flow of air conditioning air.

I recently took a look at a project for a hall where the calculated dry heat gains from partitions and lighting amounted to 658 kW.

We have determined the constant heat gains from technology with consideration of the simultaneity factors to be 605 kW, as agreed with the investor. In the IX CHART program, we calculated the total heat gains from 600 workers to be 120.3 kW and the moisture gains to be 109 kg/h.

So the total heat gain balance is 658 + 605 + 120 = 1383 kW The total moisture gain balance is 109 kg/h We can now move on to the secret function in IX CHART, which is the automatic calculation of the required air flow rate for air conditioning. We activate the Ventilation Plant Calculator (VPC) module and fill in the required fields (highlighted in yellow frames), but we don't provide air flow rates as they will be calculated automatically. We choose the "Calculated from balance" function for the supply air and by providing our calculated values of total heat gain and total moisture gain, we set the temperature we want to achieve in the room equal to the supply air temperature, and voila - we get the calculated air flow rate of 312,310 m3/h!

We can immediately see what the relative humidity in the room will be - in this case RH=44.27%, and what the required cooling capacity of the air conditioning system is - in this case 2871kW.

RTo sum up, in order to remove 1383kW of heat gains and 109kg/h of moisture from the room, it is necessary to supply 312310m3/h of air at a temperature of +12oC, which requires the cooling capacity of the air cooler to be 2871kW. As easy to calculate, as much as 1488kW is spent on dehumidifying the air, that is, removing latent heat from the air. It makes sense to introduce mixing chambers or at least heat recovery sections into such a system, if possible, and we do not care about introducing such a large amount of fresh air into the room (unless we compensate for some exhaust from the technology, etc. then it is a completely different matter). In this particular case, I was forced to compensate for exhaust from the technology, so the central air handling units were designed to supply 100% fresh air, nevertheless, they were equipped with mixing chambers because the amount of fresh air must be dynamically adjusted to the number of operating exhaust fans. And that's about it. Thank you for taking the time to read this article. If the article has brought something positive to your development, and you want the website to continue to develop, where I share my knowledge, give a thumbs up, leave a comment or share it. And of course, you can help yourself and me by purchasing a license or You can just buy me a coffee :)

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