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00:02:660Michele De Carli: All right, so we start, okay? Today we talk about,
00:08:660Michele De Carli: about, about, about, about, about, about. The sizing of air duct systems, okay, so we are going to see in detail what I show you
00:18:50Michele De Carli: on Monday, and we are also going to explain how to use the tool that you have to use for the…
00:27:300Michele De Carli: for the, for the report, okay, for you, the group, the working group that you have to do, okay? Please sign in, you have time until tomorrow to sign in, or today, I don't remember.
00:38:500Michele De Carli: You don't know? Okay. Yes, so the working group needs,
00:46:820Michele De Carli: is, three, no, three points, yes? And, yes, today there are really fireworks, right? So, I promise you a very interesting, lecture, because Marco, maybe not.
01:03:420Michele De Carli: Okay, good morning to everyone. Too high expectations, or… Yeah, too high expectations, yes.
01:10:720Michele De Carli: Today, we're going to talk about the sizing of an air system, so we see different kinds of air systems, and understand, more or less, how we can area out the sizing, and how
01:23:650Michele De Carli: we can make a detailed design of such a system. At the end of the lecture, the last 5 minutes, probably, I will show you the application, or one specific case I'm working on.
01:38:250Michele De Carli: And so, you can understand also the complexity of an air system, and which are the main issues we can find as designers when we go through such a kind of system.
01:52:600Michele De Carli: So, a brief introduction, if the system works.
01:57:910Michele De Carli: No? Rate? Yes?
02:03:70Michele De Carli: I won't go into the detail of this, but according to the Ashrai, we can, divide, the…
02:19:170Michele De Carli: HVAC systems into three macro categories. The first one is the full air system, in which, through one system, we are providing both the quality of indoor air
02:31:450Michele De Carli: and the thermal comfort. The second one is the mixed system with most of the heating and cooling demand provided by the
02:41:790Michele De Carli: hydronic system, for example, radiators or running systems, and with an additional, load provided by an air system.
02:54:00Michele De Carli: smaller, but an auxiliary system. And then the third one is a solution, more practical, more used in the residential case, where the hydronic only provides all the load, and then we use natural ventilation to create an indoor environment that can be also good for certain reasons.
03:17:600Michele De Carli: But in this case, we're focusing on air systems, so we will compare two different kinds of systems, the full air solution, where we have higher volumes, higher flow rates, but the concept is that in this case, the full air system provides both the
03:37:80Michele De Carli: thermal load in both summer and winter, and so with the full… when we loaded the full heating load.
03:46:410Michele De Carli: And also provides the, air changes to fulfill the in-order quality requirements. So, we have, that this system needs to provide a very high volume flow rate.
04:01:530Michele De Carli: of air.
04:02:990Michele De Carli: In the second piece, we talk about the primary system. In Italian, we talk about the Metilacion electrical. It's only a regulation system, so in this case, this kind of system works with a lower,
04:18:29Michele De Carli: airflow rate, but only to fulfill the indoor air quality. The thermal requirements are provided by a non-signer system that can be hand heat pump connected to the radiant, or that can be some radiators connected with a gas boiler or another solution.
04:38:830Michele De Carli: If this comparison is clear, we are only talking about a brief introduction.
04:45:20Michele De Carli: we go more in deep to see how it is built, a fuller system. So, this kind of machine, we are talking about very big machines, as you're going to see, which is the size we are talking about. There is a generation system that provides
05:02:590Michele De Carli: the water to the air and lead unit, which is later why, and then there is this big machine that is the air-and-li unit, inside which, all the transformations of air occurs.
05:15:490Michele De Carli: And then, there is an air distribution system with the ducting that is delivering air to all the different environments, and at the end of the ducting, there is the air terminal unit from which the air is introduced in the environment, or is extracted by the environment.
05:35:420Michele De Carli: Here, we can see a schematic of this kind of system. So, the air is taken from the outdoor.
05:43:770Michele De Carli: In this part, let's see if I can… Throw you up.
05:48:330Michele De Carli: It's not hinted.
05:50:640Michele De Carli: That goes up.
05:53:980Michele De Carli: Lazar.
06:00:980Michele De Carli: That is Krizalik.
06:02:940Michele De Carli: these things.
06:06:260Michele De Carli: It's an okay food.
06:11:240Michele De Carli: 50.
06:12:830Michele De Carli: So this is a schematic of such a solution. We have it taken from the outdoor air with degrees that are usually placed outside the building, or, you know, usually it's also placed outside, or in some,
06:29:570Michele De Carli: environments that are, for example, the basement, or some banks in which we only, place the machines.
06:41:10Michele De Carli: No, you can talk to me, Wiley.
06:43:240Michele De Carli: As you can see with the file. Usually the file is also placed inside here in the world, we see some,
07:00:880Michele De Carli: Okay Decision.
07:05:10Michele De Carli: Per que Zoom, assume, Zoom.
07:09:150Michele De Carli: Zoom tone.
07:14:970Michele De Carli: Okay.
07:22:710Michele De Carli: Yes. At the end.
07:25:480Michele De Carli: So…
07:26:830Michele De Carli: I was telling before, very easy schematic of a system with the taken of the outdoor air, then air rendering unit.
07:36:20Michele De Carli: That is this machine that can be placed outside, usually on the roofs, if we are talking about flat roofs, or in some underground floors, that are built for this kind of…
07:52:730Michele De Carli: Oh, just to be the places where we put the machines. And then, we can see that we have the ducting, that can be divided, and that can split according to the path that the air mass
08:07:630Michele De Carli: May before entering in the desired environment, and at the end, we have the different terminal units. What I want to show you is that, as you can see, we will see in later more in detail, that the section of the different branches changing changes according to the place where the pair is extracted from the data.
08:30:250Michele De Carli: The sections is very important because the change in section is made in order to limit the pressure losses and to provide the air the adequate pressure, in order to reach the terminal device and the exhibit here at the correct velocity.
08:52:340Michele De Carli: So, let's go more in detail. What does it mean to size an air system?
08:58:480Michele De Carli: So, it means to define the…
09:04:350Michele De Carli: Full layout of the machine, so where the machine must be placed, which is the space the machine requires according to the volumes that we need to sit, which is the path of the air throughout the building, so every level, every floor, every single path.
09:23:260Michele De Carli: which is the size of the ducting, where the ducting must enter and exit, where is the place where we have to put the terminal units, terminal units like this one. You can see that also in this room, we have a live,
09:40:70Michele De Carli: Live in love. I live in love.
09:43:10Michele De Carli: Okay? But you can see that we have the, the different branches and the terminal devices that are placed in form.
09:51:290Michele De Carli: in places. So, the…
09:55:280Michele De Carli: The sizing of the system at the end, allows you to decide which is the full path of the air inside the building, and all the components that you need to provide the air at
10:09:560Michele De Carli: The defined airflow rate at the defined temperature in the specific place where you want to introduce it.
10:18:630Michele De Carli: Which are the input of this design phase. First of all, we need to define the case study. So, where are we,
10:28:830Michele De Carli: What do we want?
10:30:440Michele De Carli: wanted to introduce the air, which is the end user of the building, how much air I must provide according to the end user.
10:39:950Michele De Carli: Then, I also need to know which is the age vacuum vibration that I decide. Am I talking about a full air system or the primary air system? This is very important, because according to this, we can decide the machine, the kind of machine, and the flow.
10:54:740Michele De Carli: And if we want to have a constant air volume for a valuable air volume system, Mmm…
11:06:140Michele De Carli: Okay, go ahead.
11:16:230Michele De Carli: At the end, the output of the sizing procedure will be the depth length and the design of the machine, as was reported, and the choice of the machine of the system.
11:31:890Michele De Carli: What is important is that, in this case, We are gonna…
11:36:830Michele De Carli: focus on the sizing of the system, neglecting
11:40:930Michele De Carli: the space air distribution. What does it mean? It means that, in this case, we will always assume to introduce the air on the ceiling, so on the upper part of the building, and extract it on the upper part of the building, so every time on the ceiling. We are not considering all the ventilation strategies that Professor Dakari showed you, so the displacement
12:04:940Michele De Carli: ventilation compared to the mixing ventilation. This is an aspect that we can treat separately, and in every case.
12:14:690Michele De Carli: It is something that the sizing of the system that we will see here is valid for every ventilation strategy.
12:24:690Michele De Carli: So… Let's go Maureen.
12:30:530Michele De Carli: The sizing of an air system is a procedure that we can summarize into 8 different steps.
12:38:320Michele De Carli: Now, this is something that I usually show for simplicity for you to understand which are the different steps.
12:48:50Michele De Carli: If some of you will work in an engineering company, or in a studio.
12:53:150Michele De Carli: You will find that sometimes some of these steps are
12:58:250Michele De Carli: Neglected. Some of them are, more, concentrated.
13:04:840Michele De Carli: But these aspects are all the aspects that you will be required to consider when sizing, such as
13:13:220Michele De Carli: So, we will go into deep of each one of these points, and understand how you can, reach the final,
13:24:20Michele De Carli: choose of the appropriate machine. That is the last step, and once you have done it, you can consider that your sizing procedure is over.
13:32:270Michele De Carli: So, let's start from the first one, that is the definition of the thermal load and the indoor air quality requirements.
13:41:150Michele De Carli: I forgot.
13:42:610Michele De Carli: I put in this slide some of the books that I use as a reference. The first one, the Book of Fundamentals, is in English, it's very important. It's one of the strongest books for the HVAC designer. You can find it in the library, the university library. We have also the last version.
14:02:440Michele De Carli: And in Italian, for Italian students, we have Manuel Latino Technico, that is a very good manual, where you can find more or less everything about HVAC design. It will not be printed anymore.
14:15:00Michele De Carli: Really? That was the boss of, they're not gonna print anymore the model. Picato.
14:28:680Michele De Carli: Okay.
14:30:30Michele De Carli: let's start from the calculation of airflow requirements. This is valid for every single building, so once you start from
14:40:380Michele De Carli: a specific legal.
14:42:850Michele De Carli: The first thing you have to do when you size in your system is to define in which category you want to work at.
14:52:50Michele De Carli: So, there is a standard, that is the 16798 in the first part. In the NXB, you can find the different categories associated to the indoor air quality.
15:06:520Michele De Carli: We are not talking, in this case, about the thermal controls, or not about the air temperature, but only on flow rate. These are the flow rates that I need to change in an indoor environment.
15:21:420Michele De Carli: Replace… ventilation means replace the polluted indoor air with fresh outdoor air.
15:28:950Michele De Carli: So, the main purpose of this, in this case, is to lower the CO2 and to dilute all the pollutants that can be formidated, that can be every other pollutant associated with the human emission and building emissions.
15:46:260Michele De Carli: So, this standard requires some flow rate that we must, in every moment, provide to a woman.
15:57:340Michele De Carli: In this case, we can see that the standards describe four different categories. The first category is the high
16:07:950Michele De Carli: Yes? So far, we just, okay, simplified this approach, okay, so we used… I told you that usually in Italy, we used to have 10 liters per second per person, okay, which is, of course.
16:22:700Michele De Carli: as we have seen, it's a good condition if we are considering someone from outside, okay, rating the indoor environment. If you are inside an indoor environment and you're rating this environment, then this is a very good, high-quality,
16:42:110Michele De Carli: the Mount of Fury.
16:44:00Michele De Carli: The new… this is the new standard, it's European standard, okay, and it is… has been introduced in Italy quite recently, okay?
16:52:230Michele De Carli: Quite recently, okay. So, still, in Italy.
16:58:770Michele De Carli: we are still using 10 meters per second, but this is the way, okay, you should, okay, select, choose the formatting for it. So we have four, let's say, classes of,
17:14:310Michele De Carli: quality over here, okay, according to the standard, looking also at the thermal comfort, for instance, okay, but because it's the same standard, okay, so it's the standard environmental quality.
17:26:970Michele De Carli: And there are different ways, different approaches, okay, and you can choose among the three, because before it's long, okay, usually the second one is what you're expecting in any building. Yes, please.
17:41:520Michele De Carli: What are the values of the liters per second? Now I'm going to show you. Yeah, I wanted just to introduce that, because I have always, okay, talked about 10 liters per second, okay? And this is a little bit misleading, so that is why I wanted to, to tell you that, okay?
18:00:00Michele De Carli: Yeah.
18:01:860Michele De Carli: So, I show you a part of the standard.
18:07:430Michele De Carli: Yeah, there's some bustler.
18:19:820Michele De Carli: Yes. So you know that you are… you have the availability of the… of the European standards, right? You know that you can…
18:30:520Michele De Carli: fully… have access to the European standards? Do you know that? No. As… students from University of Padua.
18:41:200Michele De Carli: These were assigned.
18:42:790Michele De Carli: British Standards Online, beef soil.
18:47:00Michele De Carli: with the academic, email, you can enter and download all the European standards. So download all the standards as fast as you can before you get the degree, okay? Or you're losing the studenti.nupt.it, okay?
19:14:150Michele De Carli: Luplicate.
19:23:850Michele De Carli: That's fair.
19:33:820Michele De Carli: May I pledge allegiance.
19:45:610Michele De Carli: I can't sleep.
19:49:10Michele De Carli: And so…
19:59:660Michele De Carli: No, porque…
20:06:840Michele De Carli: Okay.
20:09:750Michele De Carli: This is the standard, 1679.
20:13:500Michele De Carli: in the Annex B,
20:24:460Michele De Carli: Huh?
20:27:350Michele De Carli: No, no, vastas corre lima.
20:31:920Michele De Carli: Okay, now we should…
20:57:830Michele De Carli: Bella do Manda.
21:04:180Michele De Carli: It's amazing.
21:14:180Michele De Carli: Don't know.
21:30:800Michele De Carli: At Zoom, at Zoom, that's Zoom.
21:37:170Michele De Carli: Hash, strategist.
21:41:720Michele De Carli: Zoom, zoom.
21:46:330Michele De Carli: You gotta get rid of them.
21:57:590Michele De Carli: And the community.
22:05:750Michele De Carli: I said, oh, Alexa, huh?
22:08:580Michele De Carli: I don't.
22:18:790Michele De Carli: That girl.
22:28:310Michele De Carli: No, j'i cujour leisure… Anarchy.
22:35:310Michele De Carli: Okay.
22:38:300Michele De Carli: Porque de la tomate al course.
22:44:570Michele De Carli: Move.
22:46:960Michele De Carli: Nope.
22:54:100Michele De Carli: And so… Guessing you don't have it.
23:03:140Michele De Carli: You soak it up?
23:05:680Michele De Carli: Okay.
23:07:630Michele De Carli: So, we want to project in Zoom, okay, so…
23:11:570Michele De Carli: He's fine, because otherwise we are gonna be lost.
23:15:880Michele De Carli: in the NXB, You can see, starting from here, Nothing.
23:26:500Michele De Carli: It is provided.
23:29:700Michele De Carli: A method divided into three parts.
23:33:780Michele De Carli: To decide which is the… basis for the criteria for indoor air quality and ventilation rate B.3.
23:43:980Michele De Carli: So, here you can see what we have mentioned before. So, due to F reasons, the total minimum
23:52:780Michele De Carli: Airflow rate during occupancy expressed as liter per second per person should never be below 4 liters per second, is what we mentioned before. And then, 3 meters are provided. The first one is a method based on perceived air quality.
24:08:940Michele De Carli: You can see the table below here.
24:12:490Michele De Carli: Probably. Maybe.
24:16:580Michele De Carli: And this method.
24:19:250Michele De Carli: defines according to the category, which is the amount of liter percent per person that you must provide only for 2 door and pointed individuals. So, category 1, 10 liters per second per person, two, seven liters, the third category is 4 that you have seen is the minimum, and the fourth, that can be done only
24:40:620Michele De Carli: In places where there is no constant occupancy, or for a limited amount of times.
24:45:930Michele De Carli: is 2.5 liters per second, the first one. You can use this method, that is the easiest one.
24:52:350Michele De Carli: But, you can use also the middle number 2.
24:57:400Michele De Carli: the middle and virtue, second approach, that provides limit of CO2 concentration outside. So, it is done mainly for
25:07:930Michele De Carli: those kinds of ventilation, like the demand control of ventilation, when you can monitor the parameters inside the indoor. And so, for example, you can monitor the CO2, and in order to keep good levels of indoor air quality, you must remain below the volume indicated in the standards. So the first quality, the first category, sorry.
25:29:720Michele De Carli: Requires to stay below 550 ppm of CO2.
25:38:10Michele De Carli: Pay attention that, as it is in the table, it is…
25:43:920Michele De Carli: concentration evolved outdoor, so it means that if outdoor we assume 400, the first category requires an absolute value of CO2 below 950 ppm of CO2, okay?
26:02:220Michele De Carli: So, this is the second method. The third method…
26:07:240Michele De Carli: is another approach that provides two different values. The first one is in liters per second per person, and the second one is in liters per second per square meter.
26:19:360Michele De Carli: This is a method that can be used, for example, when we have different,
26:26:730Michele De Carli: particular coupons. So, for example, when we have very large
26:32:20Michele De Carli: spaces that are occupied by a low number of persons. So, you can use this calculator, the flow rate, according to the two methods. So.
26:43:90Michele De Carli: Considering both the occupancy and both the square meter floor area, and then decide which one you can use according to… if you want to be more conservative, you can… you can use the lower value, and you can be more, use higher values in order to provide a higher indoor air quality level.
27:02:170Michele De Carli: But this is what the standards provide, and the first step, now I will try to move to the presentation, the first step is to decide according to the standard values, which is the value of the floor air according to the indoor air quality issues.
27:23:290Michele De Carli: No.
27:24:240Michele De Carli: Hey, look.
27:27:720Michele De Carli: 17? Excellent.
27:36:800Michele De Carli: What do you mean?
27:59:940Michele De Carli: The obediento.
28:28:50Michele De Carli: It's a pushy people.
28:32:290Michele De Carli: Agunqua.
28:53:340Michele De Carli: This is very rarely have not yet.
29:15:860Michele De Carli: I will show you all the attached files at the end of the lecture to be more…
29:21:320Michele De Carli: To arrive more easily at the end.
29:23:570Michele De Carli: So, we have defined the first part of the first step. So, the indoor quality requirements.
29:31:900Michele De Carli: And the second part is Mr. One.
29:41:670Michele De Carli: You already know which is the load required by your building.
29:46:570Michele De Carli: You have calculated it through the method that, in the previous lecture were shown. So, at the end, you can have used as the input of this icing system, the heating load and the cooling load of the building.
30:01:500Michele De Carli: For the heating load, probably, you have shown the standard simplified value for the peak load, and for the cooling load, the carrier method. Okay.
30:12:350Michele De Carli: So, you have the true loads, heating and cooling load for the building, but how can I associate to this load the ventilation flow rate, the air flow rate that is required?
30:25:160Michele De Carli: The first point is to define set point indoor conditions. So, I will define for winter and for summer conditions the set point indoor.
30:36:960Michele De Carli: that requires a temperature, for example in wind, to 20 or 21 Celsius degrees, and a humidity of 50%. For summer, we will have a set point of 26 and 50% relative humidity.
30:55:250Michele De Carli: Second step, I define the delta T between the supplier and the indoor temperature. So.
31:07:450Michele De Carli: These are two ranges that we can looser between
31:14:970Michele De Carli: In the summer or winter for the sizing.
31:17:590Michele De Carli: In order to avoid some, aspect that could occur. For example, in this case, we are talking about the delta TP2 image, the set point of air, so the indoor air temperature, and the supply divertion. It means that, for example, in winter.
31:34:410Michele De Carli: If we have an indoor temperature set point that is 26 degrees, we cannot have a supply temperature higher than 20 plus 20, so 40.
31:45:190Michele De Carli: So, for the winter sizing, we will
31:48:720Michele De Carli: Define a threshold, a maximum threshold of 20 Celsius degree. No higher temperature.
31:54:940Michele De Carli: Because otherwise, we risk to have stratification, or too hot air coming inside the environment.
32:04:100Michele De Carli: For the summary conditions, we would have to reverse, because the delta T is reversed. So, in this case, if we consider a set point temperature of 26,
32:15:790Michele De Carli: We will never go below the 14 Celsius degrees, so 26 minus 12.
32:23:990Michele De Carli: Never below the 14th degrees, which is already a very, very low temperature.
32:31:840Michele De Carli: Because otherwise, we risk to have localized discomfort due to Two, quote, hair count.
32:38:680Michele De Carli: Also, we choose the optimal supply temperature.
32:41:970Michele De Carli: Between 12 and 19? You can do average, okay? You can stay around 15, 16, and here around 10, and then you will see that we will go matching between the airflow rate and the temperature to provide the wood thermal load, because at the end, the importance is affected.
33:06:570Michele De Carli: Once I have defined the supply temperature and the set point temperature, I can define which is the fan load. So, for both the heating and the cooling season, I will already have this, because this is
33:23:10Michele De Carli: the heating and cooling load, with the density of air, the specific heat and constant pressure, the delta T I have assumed, I can calculate.
33:34:640Michele De Carli: The, the airflow rate according to the law that I had to fulfill it.
33:42:350Michele De Carli: And the important point is that this is not necessarily fresh outdoor air. I can also use air that is already inside the room, reciprocate it.
33:55:410Michele De Carli: increase or decrease the temperature according to the season, and then reintroduce in the room. We will see this aspect in the next slide.
34:07:350Michele De Carli: Yes? Consider it a sensible load, not latent load. Yes, in this case, we are only talking about a sensible load, yeah.
34:15:250Michele De Carli: The latent, is something that now we're gonna see, according to how it is built here in the unit, we have to consider the latent load separately from the sensible load, okay? In this case, we are talking about sensible load.
34:34:40Michele De Carli: Okay.
34:35:159Michele De Carli: So… Once I have.
34:39:380Michele De Carli: calculated. Done.
34:43:400Michele De Carli: Airflow rate according to the environmental quality.
34:47:570Michele De Carli: The effluator for the…
34:50:980Michele De Carli: keeping season in the air delay to fulfill the order at the cooling season, I have to decide… decide which is the final
35:00:770Michele De Carli: design.
35:02:870Michele De Carli: airflow rate. That is usually the maximum among the three Morning, sure, Rita.
35:11:400Michele De Carli: according to the… that equation. I use different
35:16:810Michele De Carli: Subscript, but it's the same equation.
35:20:740Michele De Carli: So, I take the maximum, Of these three values.
35:30:380Michele De Carli: I think they're absolutely lower.
35:33:90Michele De Carli: Of these three values in order to define this one that will be my design airflow rate.
35:41:960Michele De Carli: But it is important to see that If critique.
35:50:880Michele De Carli: Let's talk about a real situation, which I have a machine, By year at Envino?
35:58:890Michele De Carli: I have blue army.
36:07:130Michele De Carli: And I needed to provide them that, my fear.
36:21:910Michele De Carli: That will be the maximum amount this time.
36:25:300Michele De Carli: In this case, consuming both eating and food.
36:28:940Michele De Carli: What I absolutely need is that this part
36:33:510Michele De Carli: is fresh air coming from the outside. I need to replace this amount of air from this environment taken from the outside.
36:48:80Michele De Carli: But this part, as I mentioned before, is not necessarily coming from the undorf. I can also take it from inside here.
36:56:690Michele De Carli: So, what I can do is to take some care from, right?
37:00:640Michele De Carli: recipient, And we're putting NR.
37:06:10Michele De Carli: Anger.
37:07:760Michele De Carli: Really making a path in which this portion of air comes back to the air in the unit, is treated, so it's heated or cooled, okay, and then it's mixed with this fresh air, and then reintroduced.
37:24:640Michele De Carli: At the end, what we can say is that, in this case, we will have that this portion is not
37:31:230Michele De Carli: Alternative button.
37:34:20Michele De Carli: We thankfully.
37:36:650Michele De Carli: These are ongoing.
37:40:270Michele De Carli: As we defined before, the design value is the maximum, between… the Lord.
38:01:520Michele De Carli: I can also define another value that is very important, that is this M ratio.
38:08:350Michele De Carli: The M ratio, Ease.
38:12:400Michele De Carli: the ratio?
38:13:930Michele De Carli: Between them.
38:15:750Michele De Carli: The portion of air necessary for indoor air quality, and the design.
38:29:450Michele De Carli: We can simplify this equation, Because, you will see that with practice.
38:36:210Michele De Carli: The load, the airflow rate required for the load, will be always higher than the flow rate required for radio quality.
38:46:750Michele De Carli: So, this equation… Most of the time is this one.
39:06:320Michele De Carli: Because this is usually the maximum value.
39:13:900Michele De Carli: Once I get introducing
39:17:540Michele De Carli: the air inside an environment, I have also to extract some air. For the quantify me.
39:27:230Michele De Carli: Here, my control volume.
39:35:40Michele De Carli: I will find that… the air that I introduced.
39:39:510Michele De Carli: I also have to start. So, the… M.
39:44:660Michele De Carli: design.
39:46:440Michele De Carli: must be equal to the N.
39:49:620Michele De Carli: Recyculation, plus… These are known value.
39:58:300Michele De Carli: This is if I wanna… See, this control volume.
40:06:610Michele De Carli: But if I increase the posture volume.
40:09:520Michele De Carli: And I take holding back with me.
40:12:10Michele De Carli: Okay.
40:13:720Michele De Carli: Also, including this fact, And my control volume becomes…
40:21:30Michele De Carli: The whole building, and the system.
40:24:50Michele De Carli: I can see that the only flux that entered is the neural quality path, and the only one detects it is this another variance, so I can tell that
40:35:330Michele De Carli: these… M here is equal to
40:40:300Michele De Carli: indoor equality. So the air that I introduced for indoor equality purpose, I also have to extract and throw on the outside environment.
40:53:980Michele De Carli: At the end, The recipulation value.
40:59:360Michele De Carli: will be.
41:02:40Michele De Carli: the design value, minus… You know, for internal reporting.
41:11:480Michele De Carli: everything seems a little bit complicated, but one year will take back to your… we'll go back to your notes.
41:19:310Michele De Carli: when you get into… when you're familiar with this, it is very easy. I only take some air… fresh air from your door, and I have to extract the same amount. I can recirculate a portion, and this is the relationship between all these.
41:39:640Michele De Carli: claims.
41:46:770Michele De Carli: Why have I told you all this?
41:50:60Michele De Carli: Hold on.
41:51:190Michele De Carli: Because let's imagine that we are moving, To three different environments.
42:00:230Michele De Carli: All these three environments are supplied by the same machine.
42:05:350Michele De Carli: So, this error and unit, not… don't, doesn't, provide all here to one environment, but to three environments.
42:16:240Michele De Carli: I will agree.
42:18:340Michele De Carli: Yang value for the first one.
42:20:530Michele De Carli: So, according to the ratio between the industrial quality value and the design entry.
42:26:100Michele De Carli: The first one, the second one, and the third one. And we find, of course, three different ratios, because every environment will have its own capacity, the different thermal loads, different heating and cooling environments, and so on.
42:44:530Michele De Carli: And according to this, I will find 3 different end values.
42:48:800Michele De Carli: But essence.
42:52:40Michele De Carli: the M value.
42:55:30Michele De Carli: It's the relation between this value And this friend, I won't have the possibility
43:03:930Michele De Carli: to change it according to the room I provide, because it will depend on the machine. I cannot provide… if I divide this into three parts, I won't have the possibility of
43:18:190Michele De Carli: putting M1 here as a ratio, M2 here, and M3 here. I would have to provide always the same ratio between fresh air and total air.
43:29:330Michele De Carli: In this way, what I have to do, is to… Take the maximum value, In this case, it's 054.
43:38:630Michele De Carli: and change… Dude.
43:43:950Michele De Carli: value of the, this ratio in all the rooms, so I will have to recalculate the required amount for the indoor quality.
43:59:340Michele De Carli: But I need the same, and when, yes.
44:03:160Michele De Carli: Yes.
44:05:140Michele De Carli: It means that in these two rooms, I will reciprocate less than what it is.
44:11:360Michele De Carli: I decided at the beginning, and I will provide more fresh air, so we'll be in higher indoor air quality compared to the one I expected, and compared to the one I standards tell me.
44:24:700Michele De Carli: But this is necessary, because I have only one machine, and I need to provide 3 different rooms, okay?
44:32:210Michele De Carli: Yep, maybe, well…
44:38:90Michele De Carli: Thanks.
44:39:10Michele De Carli: I will try to explain what I want to say, but I mean… So, as you have seen, you have three… the possibility to define three category… three category levels of indoor equality. Okay, so in case you could also be allowed to have, in one room,
44:58:750Michele De Carli: smaller level of quality, okay? So, I mean, This is true
45:04:710Michele De Carli: Okay, but in case you have a huge difference between what you should recipulate, okay, if just one room is necessary.
45:14:320Michele De Carli: taking more air as percentage, okay? You could, in principle, choose to have one room at level 3, and all the other rooms as level 2, okay? So…
45:27:860Michele De Carli: We have always tools, okay?
45:30:330Michele De Carli: Analyzing quite a bit, okay?
45:34:70Michele De Carli: But in general, this is true. You should consider the minimum amount of worrying, okay?
45:41:160Michele De Carli: Sorry, the, the, the, the, M. The, M.
45:51:540Michele De Carli: What the heck was this found to?
45:59:590Michele De Carli: development.
46:03:520Michele De Carli: Okay.
46:05:270Michele De Carli: So… At the end, we defined the value of
46:12:610Michele De Carli: the design value that we need. We have defined the indoor air quality requirement, the thermal load, and then we have seen how to find, finally, the design parameter.
46:24:320Michele De Carli: And which is the ratio between the indoor air quality and the total amount of flow rate for each room that I have to design.
46:33:910Michele De Carli: The next step… is to choose.
46:41:970Michele De Carli: The next step is to choose how gear is delivered to the building.
46:49:340Michele De Carli: And the first part of what we see.
46:53:240Michele De Carli: It is to, define which is the vendor.
46:58:80Michele De Carli: This is a path that usually is done at the end, so now we see that's the third step, but the first part, the first and second step is fixed, then all the others are a little bit…
47:11:510Michele De Carli: can be done in a different order. Anyway, we will see how to define this venture.
47:19:640Michele De Carli: Or better. I will show you at the end, because if I close the presentation and open the PDF, probably we will lose the rest of the lesson.
47:28:330Michele De Carli: Which are the… Main purposes in this case. I will have some data shifted.
47:38:110Michele De Carli: In this case, this is Trox, Dataship. Trox is a company that, provides these
47:46:900Michele De Carli: events, very similar to this one, probably this… maybe this can be, of this company. Yeah. So this is a very important company. They provide you a data sheet, a data lecture. I will show you.
48:05:420Michele De Carli: what I will do, when I have
48:08:960Michele De Carli: history. So, I started from a situation in which now I excluded the only from my calculation, and I started from the party which
48:19:00Michele De Carli: I have my bizarre value, N.
48:23:290Michele De Carli: For each room of the evening.
48:26:380Michele De Carli: I have different ventilation that I have to provide, and one in shock.
48:32:210Michele De Carli: And 3, and then 4 freezing.
48:35:250Michele De Carli: I will provide that.
48:37:850Michele De Carli: that enters maybe here, I don't know, will make this, will enter this part, this part, this part, and this part. In the very low level of detail now, we are not…
48:49:140Michele De Carli: Looking at this.
48:51:970Michele De Carli: So here, I will provide this, this, this, and this.
48:56:300Michele De Carli: But maybe this rule is 2, because then if I put only one exit here, maybe close to the wall, or at the center of the room, maybe I cannot reach the whole meeting. So, I can decide to
49:10:440Michele De Carli: take here, doctor.
49:12:800Michele De Carli: And the lady.
49:15:430Michele De Carli: Provide ink, In 6 different points.
49:21:190Michele De Carli: So, I assume that my efflu rate enters here, and then goes to each single dot.
49:31:490Michele De Carli: Or maybe I can find a different solution, which I directed from here, I take this 3 and take this 3. Well, this is up to the desire.
49:44:10Michele De Carli: And what I would do is to take every single one, define them, And to first.
49:51:50Michele De Carli: Time to recycled, and so on.
49:54:300Michele De Carli: Of course, this will be M2 divided by 6, because I always have to provide uniform care in all the buildings.
50:03:310Michele De Carli: In all the room.
50:05:740Michele De Carli: And I will assume a distance.
50:12:160Michele De Carli: I make a hypothesis on the distance.
50:14:880Michele De Carli: Then, according to the datasheet, I calculated it as 0.5,
50:20:370Michele De Carli: So, the distance at which the velocity becomes 0.5 meters per second.
50:31:280Michele De Carli: And what I have to check, huh?
50:34:490Michele De Carli: is that I have a good air distribution. What does it mean to have a good air distribution?
50:41:560Michele De Carli: It means that This, that is the distance from the… From the…
50:50:230Michele De Carli: for the output of the line L0.5 never overlaps between true.
50:59:270Michele De Carli: Thanks, sir.
51:00:460Michele De Carli: And also, they are not part one to each other.
51:05:610Michele De Carli: So, it's a qualitative.
51:08:270Michele De Carli: indication.
51:11:100Michele De Carli: But it is like this.
51:13:700Michele De Carli: You will never have someone that will go there checking if you have made a correct design, but…
51:21:540Michele De Carli: But complaining a lot. If you have been to Engineering Hub, our new fantastic building, probably you have noticed that there is, like, having a tornado, because you have here at 18 cents a degree flowing everywhere at a high velocity. There is a clear, error in the sizing of the areas.
51:46:340Michele De Carli: If you don't have a good check distribution, you come back, you make another hypothesis, you make the vents closer or more distant, and then you check another time the population.
52:04:190Michele De Carli: So, this is about… the vent.
52:08:900Michele De Carli: The next step is the air velocity.
52:15:60Michele De Carli: The air velocity is very important, only for one reason, that is the acoustic issue.
52:21:980Michele De Carli: The air moving inside the duct is very loudly. It's very… it needs to be very controlled at,
52:33:480Michele De Carli: The velocities that you can see here.
52:36:980Michele De Carli: We can distinguish, from a schematic point of view, between a main dart, secondary darts, and final branches.
52:44:910Michele De Carli: And for different hand-use buildings, you can see here, we can accept different velocities.
52:53:320Michele De Carli: For residential, as you can see, the air inlet and outlet must be below 3 meters per second.
53:00:170Michele De Carli: But yeah, these are limits that you have to take and not overcome.
53:07:540Michele De Carli: In order to avoid problems like being inside the room and hearing continuously.
53:14:90Michele De Carli: The, loud of the air that is flowing inside the dust.
53:24:420Michele De Carli: Next point.
53:26:720Michele De Carli: which is the correct shape I should select for the room. We have two different kinds of ducts. The
53:34:700Michele De Carli: round answer.
53:36:460Michele De Carli: Easily?
53:37:660Michele De Carli: And remember that, this one.
53:43:860Michele De Carli: Which is the best one, of course, the Roundup.
53:48:630Michele De Carli: Because inside the roundup, here streamlines.
53:54:380Michele De Carli: are uniform.
53:58:820Michele De Carli: And there is lower turbulence.
54:01:880Michele De Carli: Inside a rectangular duct, A big section here.
54:09:610Michele De Carli: The flow will move this way.
54:15:280Michele De Carli: And here, I would have Some turbulence products.
54:20:420Michele De Carli: Making all the flow becoming turbulent very peaceful.
54:27:520Michele De Carli: Which is the problem of round map, why we don't put round lap everywhere for a space station. If I have a false ceiling that
54:37:360Michele De Carli: Here, there is the, that's the…
54:47:800Michele De Carli: That's the most important piece, it's the second floor of the building.
54:53:510Michele De Carli: And this is the seating.
54:56:210Michele De Carli: Of course, if I have to optimize the space and historically that inside the first ceiling, so the difference between the start of the second floor of the space, I have, if I need a round act.
55:10:640Michele De Carli: I am this, and if I am the Radha, I am this.
55:15:330Michele De Carli: it's quite easy to understand that that can mean… I have more area to this party. So, most of the time, that's a rectangular.
55:26:560Michele De Carli: But the preferable one, if you have a security in residence, in residential buildings, you can place this one much better in terms of
55:34:710Michele De Carli: Loudness, acoustic, prevention, and also, in, the… Movement of the air.
55:49:790Michele De Carli: How can I calculate the dissection of the duct?
55:53:430Michele De Carli: By setting the velocity, the length, I showed before.
55:58:460Michele De Carli: You know which is the automatic flow rate, because we have decided in the previous step, according to different branches, where the N must go.
56:07:680Michele De Carli: you set the velocity, you calculate the surface, and then you decide from the surface which is the dimension. So, I have the surface.
56:19:30Michele De Carli: I want rectangular that, I can calculate diameter, I have the surface, I want, sorry, the circular duct, I can put the diameter, the rectangular duct, I can complete diameter.
56:28:890Michele De Carli: Only one thing that… It's the first time, I say, no lectures, but…
56:35:300Michele De Carli: This is something that… they told me, this is a very important rule. The ratio
56:46:470Michele De Carli: Beautiful.
56:49:140Michele De Carli: Better. The ratio, let's do A on B, maybe it's easier.
56:54:940Michele De Carli: He owned me.
56:57:70Michele De Carli: No work memory.
57:00:180Michele De Carli: Yes.
57:01:650Michele De Carli: Otherwise, and often programs amount.
57:06:660Michele De Carli: Yeah.
57:09:100Michele De Carli: Through Bones.
57:11:350Michele De Carli: This is an engineering rule that is very common and very well known.
57:19:690Michele De Carli: I have decided that the flow rate, the distribution, the duct section, everything else.
57:27:130Michele De Carli: The last part is depression or unfinished.
57:31:50Michele De Carli: Why do I need to break the pressure drop? Because, as you know, once you have to choose a machine, I need to have the precise value.
57:39:670Michele De Carli: of delta P that this machine must win, overcome in order to make the air reach the different environments.
57:49:250Michele De Carli: I will go very fast on pressure drop, because you should already know anything, everything about that.
57:55:550Michele De Carli: So we have a distinction between localized pressure drop, that occurs in the specific part of the
58:03:310Michele De Carli: Branches, like cores, like… Events, and so on, and the continuous, continuous pressure drop.
58:13:370Michele De Carli: The continuous pressure drop, that are the drops that occurs in Along, industry path.
58:23:450Michele De Carli: Here, we have… the friction pressure losses. You know that the…
58:28:470Michele De Carli: Yeah, the three components are the synthetic energy variation, the potential energy variation, and the friction pressure loss. Of course, what we consider is always this one, and in the catalog, in the data sheet, you will always find this kind of
58:45:400Michele De Carli: value, that we can calculate, distinguish between continuous and
58:53:820Michele De Carli: localized. This is the equation for the continuous pressure loss calculation.
58:59:690Michele De Carli: And, you can also find some,
59:05:600Michele De Carli: Graphs, some charts, in order to calculate them.
59:09:220Michele De Carli: Have you shown this? Okay, so you already know that you can find the different diameters in the slides, and you have this, brown, dark section, dark part of the chart.
59:24:920Michele De Carli: That is the, good choice for the, for the pressure losses.
59:37:410Michele De Carli: So, what I told you before is that… nope.
59:48:590Michele De Carli: beside the section according to the velocity. So I have the flow rate, for each branch.
59:56:830Michele De Carli: I assume with their velocity.
00:03:70Michele De Carli: I calculated this section.
00:06:210Michele De Carli: And then… Did they mention?
00:10:140Michele De Carli: That can be the diameter, or the dimensions of the camera.
00:15:760Michele De Carli: Then I calculated the pressure losses.
00:19:420Michele De Carli: I have grid value, for example, in the…
00:23:630Michele De Carli: the longer path, strict path, I have 7 Pascal per liter.
00:34:190Michele De Carli: I check in the chart, and I can see that the maximum value that this
00:42:220Michele De Carli: allowed is about 5 pascal per meter.
00:45:400Michele De Carli: Usually, we work between 2 and 3 pascal per meters.
00:49:680Michele De Carli: This is the best… the best solution.
00:53:600Michele De Carli: One true imposcatometer. When we arrive, which pipe is similar enough.
00:58:930Michele De Carli: So what I have to do?
01:01:310Michele De Carli: ease.
01:03:280Michele De Carli: to consider.
01:05:100Michele De Carli: A lower the velocity.
01:08:250Michele De Carli: Recalculate S, recalculate math.
01:12:160Michele De Carli: We calculate.
01:13:580Michele De Carli: the no-season.
01:18:480Michele De Carli: You will never have to…
01:21:870Michele De Carli: engineers that charge the size two systems. Also, if they have all the same input value, you will never have the same result, because
01:32:730Michele De Carli: This procedure, as you can see.
01:36:190Michele De Carli: depends on you. Also, this procedure, the ratio, the M ratio, the decision of the indoor and quality levels.
01:44:280Michele De Carli: And also, the smarter depends always on the soul.
01:48:260Michele De Carli: This is the procedure, but then it's up to you to decide which is the final solution, best one.
02:02:320Michele De Carli: Localized pressure drops, you know, they depend from a constant value, that is, this C value.
02:09:960Michele De Carli: And according to the velocity, You can calculate by taking these values in the table.
02:18:350Michele De Carli: So you can see, for example, a curve, a 90 degrees curve in the round section. It depends on the geometry, for example, here, the radius and the diameter of the internal duct. According to the ratio between the two, you will have two different values
02:36:470Michele De Carli: For better, more different values of
02:39:880Michele De Carli: the pressure loss is constant, C in this case.
02:46:40Michele De Carli: And then, you can calculate the localized pressure losses.
02:51:600Michele De Carli: You have seen it into detail, I think, also in this course, but in fluid mechanics, the course that is dedicated to
03:00:40Michele De Carli: As a part dedicated to the calculation of localized and continuous pressure losses.
03:04:820Michele De Carli: This is the end of the table. I won't…
03:09:100Michele De Carli: Go too much into the detail.
03:14:260Michele De Carli: But you see, you have also other elements here. You have this restriction.
03:20:30Michele De Carli: Here, the increasing section. So, you take the element you need, and then you decide.
03:28:920Michele De Carli: But what we want to provide you is an Excel tool.
03:33:960Michele De Carli: That helps you to calculate in the pressure losses, because we know that sometimes there can be a lot of mistakes, it can be very long and boring to calculate the pressure losses, so in order for you to focus on the,
03:49:60Michele De Carli: On the design of the system, who will provide you the tool.
03:56:320Michele De Carli: And of course, the tool…
03:59:370Michele De Carli: does not substitute the, the sizing processor, but it only helps in the pressure loss type tool. So, at the end, I will show you how to use the tool.
04:10:340Michele De Carli: And you will have, from the tool, the final value of Pressure loss type breach.
04:17:550Michele De Carli: And, last slide, before going to the tool.
04:21:160Michele De Carli: Is this one?
04:22:550Michele De Carli: So… This is…
04:25:140Michele De Carli: a general sizing procedure, as we have seen during the lecture. I hope it is more or less clear.
04:33:640Michele De Carli: Otherwise, you can ask me.
04:36:110Michele De Carli: You can see that at the beginning, you will see the flow rate, decided the flow rate from
04:42:560Michele De Carli: For the… for each environment, considering the fresh air and the peak load for heating and cooling. Then we will choose, and we'll make a sketch, more or less a design, of
04:55:190Michele De Carli: That plays a different event position, number and position.
04:59:670Michele De Carli: Then we calculated the length of each dot and of each part.
05:05:590Michele De Carli: The duct sizing, so you decide in the section of the duct, according to what we have seen before. Pressure loss calculation with the Excel tool. At the end, the last part is the choice of the machine. You go to a producer machine. I will show you later some data sheet
05:23:90Michele De Carli: For different machines, yeah?
05:25:590Michele De Carli: And if your machine has a prevalence that is higher than the pressure losses, your sizing procedure is okay. Otherwise, you will have to go back
05:37:10Michele De Carli: to the duct sizing, and the same thing here similar. So, if your machine is not able, or I change the machine, I buy the 100ml machine.
05:46:810Michele De Carli: Otherwise, I had to change in order to try to reduce, so reduce velocity, but reduce velocity means increased suction, and especially if we have very hard designs, it's difficult to increase section. But at the end of the lecture, I will show you why it can be a problem to increase the suction.
06:07:630Michele De Carli: Okay, I think… Yeah, we can move to the Excel, to the other files.
06:20:930Michele De Carli: aussi.