Assistente AI
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00:00:950Michele De Carli: All right, so we can start.
00:06:770Michele De Carli: Sure.
00:09:940Michele De Carli: Okay, no, excuse me.
00:13:780Michele De Carli: Yes. Okay, so, welcome, and we are going to…
00:20:840Michele De Carli: Still today, okay, you are going to see how to do the reports for the domestic automotive analysis.
00:30:940Michele De Carli: Video, 5 me, okay.
00:37:850Michele De Carli: Is this one, yes?
00:42:890Michele De Carli: Okay. So, the, well, at first, of all, I would like to introduce you.
00:54:720Michele De Carli: Marigo, who is one of our research fellows, and yes, he's historically helping us in this course from some years, I don't know how many.
01:06:50Michele De Carli: 3? Okay.
01:07:900Michele De Carli: And, yes, we are going to see, let's say, this is, let's say, resuming a little bit what we have seen for domestic hot water, and at the same time, okay, deepening, deepening a little bit, the…
01:22:740Michele De Carli: The…
01:24:150Michele De Carli: issues, and also he will also show you how to do the calculation step-by-step, so that you have a guideline, okay? So, we, hopefully…
01:34:130Michele De Carli: won't see mistakes, too many mistakes, okay, in there. Okay?
01:39:20Michele De Carli: Right? Thank you. Okay. Yeah, right.
01:42:530Michele De Carli: Okay, thank you, Michael, for the introduction. Some more words, to you about myself. I'm, doing, a cooperation this period, because it's a good time.
01:56:600Michele De Carli: What about Cecilia?
01:58:530Michele De Carli: I'm working in an engineering company, and we do the designing of HVAC systems. The name of the company is InSheet Engineering, it's here in Paloa.
02:11:610Michele De Carli: And so, I want to give you some points about my experience there, and about the practical issue that designers do in engineering studios and companies.
02:23:40Michele De Carli: But… We will see it going more in deep into the practical design of the message and Twitter systems.
02:31:760Michele De Carli: So today, we are starting from a point that is more general, because we want to see how, inside buildings, water is used. And we have many ways of using water inside buildings for many purposes. For example, we know we have some
02:51:460Michele De Carli: Fixtures that use water, like the dishwasher and washing machine.
02:55:550Michele De Carli: But there are also some other features, like the toilet, the vignette, the sink, and whatever you have to…
03:05:610Michele De Carli: It's up to you, that are designers, to understand how to take water, and to take water to the user that must use water at the required temperature, because each picture will have different purposes and different necessities about the water to be delivered.
03:25:460Michele De Carli: Today, sir.
03:26:800Michele De Carli: I also highlighted a more general point. You can see here water for the fire suppression system, because sometimes in big buildings, you have also the issues of managing fire protection, okay? A building like this one, we have the possibility, not in this room.
03:45:950Michele De Carli: But there is…
03:47:420Michele De Carli: For example, the alarms and whatever you need. So, in each room, you have to take water also for the fire protection.
03:55:990Michele De Carli: And our issues is…
03:58:920Michele De Carli: Do we have to use potable water or non-potable water? So, can we drink the water that we use in each
04:05:890Michele De Carli: of this, okay? And another point is, do we have to use hot water or cold water? For example, you can prefer to make a shower with different temperatures, so how can we manage the temperature of the water that is exiting from your shower?
04:23:240Michele De Carli: Okay, so all these issues must be thought by the designer that needs to make an adequate design of the system and of tubes that take order inside buildings.
04:37:840Michele De Carli: So…
04:40:890Michele De Carli: All cylinder fixtures must be supplied with potable water. The only one that does not require potable water is the VC.
04:50:990Michele De Carli: So, some fixtures all remove the cold water.
04:55:830Michele De Carli: Dishwasher and washing machine, and the other fixtures need both hot and cold water, and will provide the mixing of the two in order to make it possible for the user to regulate the temperature of the water exiting to the specific fixture.
05:14:270Michele De Carli: Now we are gonna see how this is realized, and if you find a design project, how you can read it in order to understand
05:25:120Michele De Carli: Which is the water that comes from hot and cold dirt.
05:33:300Michele De Carli: We want to also mention, only mention in this part.
05:37:990Michele De Carli: Some issues that are specifically related to water management inside buildings.
05:45:830Michele De Carli: There are these four issues that are very important. You know that the water, is, it is important not to waste water.
05:55:550Michele De Carli: And to avoid the waste of water. And for this, an adequate piping is required, and we don't enter into…
06:06:30Michele De Carli: But these four issues, also in the future, if some of you will manage with the designing.
06:13:140Michele De Carli: you will have to face all these core issues. The waste of water, the stagnation that is very dangerous, probably Professor LeCardi already, in the domestic hot water previous lecture, talked to you about the legendella and all the bacteria.
06:30:190Michele De Carli: He's gone.
06:32:190Michele De Carli: And all the bacteria that possibly grow up in the water, especially when we are at low temperatures.
06:40:30Michele De Carli: And when the water is stagnating inside a tube or a pipe.
06:46:290Michele De Carli: And another issue, but these two issues are related, is the energy waste. So, for example, when pipes are not adequately insulated, and the too low supply temperature. It happens sometimes when you go to old houses and you make a shower, that the water cannot reach you at the temperature you want.
07:05:950Michele De Carli: This usually, in the past, was managed by increasing the power of the…
07:12:630Michele De Carli: Of the boiler, so with very high power, you don't have this problem. But, the concept of using the adequate insulation not to waste energy and to have the adequate temperature, it's an issue that must be faced.
07:28:30Michele De Carli: So…
07:28:990Michele De Carli: All this was in introduction, our focus today is the preparation of domestic hot water, but before going into this, so to understand what is the design of domestic hot water system, I want to show you some of the concepts and the schemes that you can find for buildings in the delivery of water.
07:49:190Michele De Carli: So, these are two concepts, two green concepts, examples on how you provide the water to the different fixtures.
08:01:620Michele De Carli: So, for example, the first image. I don't know if I can make the pointer. Yes.
08:08:990Michele De Carli: Okay? So, this one is a very, very simple, system.
08:16:790Michele De Carli: Okay.
08:22:40Michele De Carli: Whoa.
08:24:410Michele De Carli: So, this is the first very, very simple design. You can see that you have here a group where all the pipes arise. You…
08:37:429Michele De Carli: having this particular design, two pipes, a hot pipe and a cold pipe.
08:43:980Michele De Carli: This is only potable water, so both hot and cold comes from the afternoon. They are treated in order to make it potable.
08:55:210Michele De Carli: So, you have two pipes, one cold and one hot, that means that the first one, the hot one, that is this one, arrives from the heating device, probably, I don't know, it can be an heat pump, it can be,
09:13:250Michele De Carli: A boiler, electric boiler, gas boiler, I don't know, depends on the case. And the second one, that is this one, that is the blue one, is full water that comes directly from the absolute.
09:24:690Michele De Carli: Here you have both the tubes, and then each tube run, through the building, and go below, usually. Not always, but usually go below the,
09:39:380Michele De Carli: picture, and connects… it is connected with the picture itself. You can see that the only one is the VC that have only the cold connection.
09:53:330Michele De Carli: The second one, the second scheme, is exactly the same, but it has the water recirculation.
10:02:640Michele De Carli: Probably if you have never heard about the water recirculation system, there is a law and European standards that says that
10:13:540Michele De Carli: When you open one fixture in your house, and in 30 seconds, you don't have the hot water that is exiting from the fixture, you have to install the reciprocation, okay? This is…
10:26:930Michele De Carli: Something that…
10:29:470Michele De Carli: It rarely happens, but this is what the standard says. And so, in the big buildings, usually you find also the recirculation tubes. So you have three.
10:40:440Michele De Carli: Tubes that, are coming and exiting from the
10:47:450Michele De Carli: From the… from the center, from the…
10:51:960Michele De Carli: Yeah, from this part, where all the bulbs are put, and you will have that, as before, the hot and conductor right below the specific device, and then
11:03:720Michele De Carli: The part of the hot duct is increased and comes back to the heating system through this lower valve.
11:15:460Michele De Carli: Which is the advantage of this system. In the recirculation, you always have hot water that is flowing inside, so it means that
11:26:180Michele De Carli: This circuit will always have a flow rate.
11:31:430Michele De Carli: The advantage is, first of all, you don't have stagnation, so the risk of legionella is lowered. The second one is that you always have the water that is
11:45:150Michele De Carli: here, here, and here, at the required temperature. So, if you are supplying water at 60 cents degrees, you always have 60 cents degrees here, here, and here.
11:56:650Michele De Carli: And in the previous case, in the previous case, in reality, you don't, because if you are not requiring hot water here, here, or here, here, the flow rate is blocked, so there is no water flowing inside. So you have water stagnating, and which is the temperature? We don't know.
12:14:120Michele De Carli: If you are not opening the shower, or you have not opened the door.
12:18:840Michele De Carli: 15 hours, and you are now used the bathroom.
12:22:540Michele De Carli: before you have to hear 66 degrees, you need a lot of time. So, energy losses, of course.
12:29:620Michele De Carli: In this case, you also have financial losses, because you… nothing… nothing comes for free, otherwise all the homes would have recirculation. You will have a pump that is always making your water flowing, so higher cost for the pumping. But this is just…
12:45:830Michele De Carli: an example. Usually, what we do is to have
12:50:320Michele De Carli: This solution in bigger buildings, and this solution in, for example, small houses or residences.
13:01:40Michele De Carli: Let's go on with another example.
13:04:850Michele De Carli: This is an example of a bigger house, and the distribution is different than below… than before. Before, you had that the distribution pipe had some points in which the sanitary were connected. In this case, you have a different connection. It is called manifold connection.
13:24:770Michele De Carli: connection. So you have two manifolds in this case, but you can also have one or three, depends on the size of the building.
13:31:430Michele De Carli: The life was, as you see here, now we have also a higher level of detail. You have the connection to the aqueduct that is this one, they call the connection, that comes here and supplies
13:45:690Michele De Carli: the cold water that then will go to the different fixtures. On the other side, you also have that it supplies the heater. This is… A gas.
13:58:70Michele De Carli: boiler, I think. Usually in this size, you find the gas boiler. You have the gas boiler. Here, the water is heated up, and then it is connected to the two manifolds, where all the other devices are connected.
14:12:330Michele De Carli: Here the difference than before is that each
14:16:130Michele De Carli: single device has its own connection. As before, you can see
14:22:930Michele De Carli: That the toilet only has cold water. Also, the dishwasher and the washing.
14:30:240Michele De Carli: Previously, I told you that the VC can be connected to non-potable water in big buildings when there are a lot of VCs. For example, you can have an adequate connection with water non-potable, that means that comes from the island, but has a different treatment.
14:46:30Michele De Carli: that supplies all the receipt of the building. This is also a possibility. I didn't,
14:51:520Michele De Carli: take, here a picture of a scheme like this, because it's very easy. If you don't follow me, please ask me, and raise your hand, and…
15:01:10Michele De Carli: You can do the pricing whenever you want.
15:03:630Michele De Carli: Last example is a bigger one. You can see here many different buildings, many different, houses.
15:12:150Michele De Carli: that are connected to a different system. This is a centralized domestic hot water system, so it's much bigger than…
15:20:320Michele De Carli: previous one. You can see that here there is also a clank, that,
15:28:230Michele De Carli: later we will see more in detail. And here we have the connection with the different manifolds. Each
15:37:800Michele De Carli: Building, each house, each…
15:40:400Michele De Carli: apartment has its own manifold, and then the logic is exactly the same than before. I want to show you here, more in detail, which is the connection with the recirculation. Here we have the recirculation, so the water supply that comes
15:56:530Michele De Carli: Here, if required, it takes it from this.
16:01:650Michele De Carli: And if not, the water continues flowing here and comes back in this part, where it can mix through
16:12:190Michele De Carli: Things?
16:13:300Michele De Carli: Or, it enters the… The tank, and so it preheated
16:21:800Michele De Carli: preheat the tank, or it is mixed with the cold water that is previously mixed with the hot water, so that we can preheat the cold water in the refrigerator. Here, there are different connections. Then, the important point here, we have
16:41:40Michele De Carli: We have different solutions, but it is important how we then set the control of all pieces.
16:50:120Michele De Carli: Here, there are different components, and we want to enter this. You will see it probably in a dedicated lecture, but these are all safety, and this is, for example, the expansion tank, the…
17:04:630Michele De Carli: Okay, and here there are many different, components. You can see the power I was talking before.
17:13:410Michele De Carli: I was telling you before, is the pump for keeping the recirculation always active.
17:18:490Michele De Carli: Any question before we move to the next part?
17:23:380Michele De Carli: Okay.
17:27:410Michele De Carli: So, let's go now to the preparation of domestic hot water. Now we have seen the schemes, and what we want to focus
17:38:320Michele De Carli: is the… The phase of the preparation of domestic…
17:45:680Michele De Carli: So, we forget the non-potable water, we forget the, the domestic cold water.
17:54:670Michele De Carli: And we only focus on how can we decide which system is the best one to prepare the domestic hot water.
18:05:60Michele De Carli: We won't have always the same answer to this question, but we will have to make a dedicated design according to what is the requirement, what is the size of the building.
18:18:780Michele De Carli: and also to our choice. But we can distinguish between four different ways that you have, I think, already seen, of preparing domestic hot water. The first important distinction is between the instantaneous production and the production with storage.
18:36:720Michele De Carli: The difference is that instantaneous production, is,
18:43:10Michele De Carli: procedure in which you instantaneously heat up the water when it is required. So, I open the shower.
18:52:850Michele De Carli: And the boiler switch on in that moment, and provide you all the heat, the power, the energy that you are asking to in order to make your shower.
19:07:830Michele De Carli: Let's try to see which can be the problem of instantaneous production.
19:14:170Michele De Carli: Let's take the example, which is very fast, I do it on the blackboard.
19:19:600Michele De Carli: Let's take an example of a shower. You are switching on a shower, and the flow rate of a shower that is important usually is around 0, 15,
19:32:550Michele De Carli: Liters per second of water.
19:34:880Michele De Carli: So, when you open the shower, this is, of course, an average, more or less, because it depends on how much you
19:45:20Michele De Carli: Or better, which is the temperature you want, because you know, in the shower, you have mixing of hot and cold water. If you want it hotter, for example, it can be slightly higher. If you want it hotter, you can have it slightly lower. Why? Because
20:01:620Michele De Carli: Here we are talking about the flow rate of domestic hot water, and not the cold water. So, if this is the shower.
20:12:220Michele De Carli: Okay? You will have the two fields that are connected here.
20:20:20Michele De Carli: with the balance, and you decide which is the size of business, the size of this, but there we are analyzing only this flow data, so this is why I tell you that this is just the average.
20:34:290Michele De Carli: We want to make a shower at…
20:36:520Michele De Carli: I don't know, 40, 45, so I should believe, 45, maybe 3 minutes high, but if you want to instantaneously prepare that water to 45, we need
20:47:880Michele De Carli: sponsor, Polymer.
20:49:760Michele De Carli: So… the equation.
20:53:470Michele De Carli: It's always the same.
21:01:990Michele De Carli: The flow rate is 0 to 15 kilograms.
21:06:210Michele De Carli: Recycled according to the density that is 1.
21:09:520Michele De Carli: SCP.
21:15:240Michele De Carli: And the delta T in Calvin, if you want to, 45, such as degrees, the temperature that enters in the
21:25:370Michele De Carli: in the boiler is the one from the oven. We can assume that, more or less, 10 Celsius degrees.
21:33:100Michele De Carli: He's a temperature, and then he's okay.
21:38:820Michele De Carli: If we make this calculation, Right? We took 1.9.
21:45:350Michele De Carli: You're welcome.
21:55:890Michele De Carli: The issue related to the instantaneous production is only one.
22:02:660Michele De Carli: Because, instantaneous production is very good. You don't have…
22:08:260Michele De Carli: Stagnation of water inside the boiler, You don't have… Any issues of,
22:16:320Michele De Carli: managing the water inside the system, inside the piping. The only problem is that you need to deliver
22:24:80Michele De Carli: 22, 25,
22:26:590Michele De Carli: 30 kilowatts, according to which is the amount of hot water you need. And which is the problem of this power, is that in… not really
22:38:540Michele De Carli: our knowledge and technologies, the only way you can provide is some time in Spain. This power is through a bus boiler.
22:47:60Michele De Carli: If you need to heat the water with an electrical resistance, for example, this, of course, in a building is not possible, okay? Because more than 3 kilowatts, you cannot provide now in some buildings somewhere, but you can never reach this power in terms of lake freeze.
23:05:510Michele De Carli: So, which is the solution in order to lower… if you don't want to install such a system in your house, so if you don't want to put a gas boiler, you need to move to another approach, which is the production with the storage, the second one.
23:23:860Michele De Carli: In this case, the storage has a lot of issues, a lot of problems. You always have to keep the storage high temperature, so you need a system that will switch on a lot of times during the day.
23:37:330Michele De Carli: Not only when your domestic water is required, you will need to manage the,
23:44:440Michele De Carli: regional inside, so you cannot keep it always at, I don't know, 46 degrees, as it was.
23:51:440Michele De Carli: keeping it there, and 46 degrees, you will have a risk of Legionella. So.
23:56:930Michele De Carli: The managing is much more complicated, but the power required can be much lower.
24:06:870Michele De Carli: So this is the first distinction we can make instantaneous production, or production with a tent.
24:14:670Michele De Carli: The second distinction is the way in which we heat up the domestic hot water.
24:23:250Michele De Carli: You can have…
24:24:570Michele De Carli: two approaches, a direct production, where the domestic hot water is directly heated by the outsource. So, we can imagine we have our gas boiler with
24:39:560Michele De Carli: the, for example, the… the…
24:44:180Michele De Carli: The flame, okay, the burning of the gas, and above the burning of the gas, there is a little tank, a little heat exchanger, where the domestic cold water enters, and it takes it out.
24:58:390Michele De Carli: and then it's delivered to the sink, to the shower, and so on. And so, in this way, you will have the direct heat up of the water.
25:07:40Michele De Carli: That then you will use in your features.
25:11:650Michele De Carli: In the indirect production, that is the second approach, you will have an operative fluid that is used as a medium, so we heat up this operative fluid, and then with the heat exchangers, this operative fluid heat up the domestic hot water that you are using in the sharps.
25:35:630Michele De Carli: Everything okay? Clear? Okay.
25:40:600Michele De Carli: So, practically, how all this aspects, happens.
25:48:680Michele De Carli: Here you have a table that is
25:51:820Michele De Carli: summary of all the ways of producing domestic hot water, except from one method, that is the production with heat pumps. There is the possibility also of producing domestic hot water with heat pumps.
26:08:490Michele De Carli: The only problem is that you lose, of course, a tank. Here, you don't have solution, because
26:18:600Michele De Carli: You need a tank, usually 40, 50 liters, sometimes also more.
26:24:210Michele De Carli: 42 for a single building.
26:26:590Michele De Carli: And it's directly connected to the heat changer, to the condenser hotter heat pump, in that case. But here, you will find, if you go today in the market, you will find more or less,
26:43:550Michele De Carli: always the same, layout. So, you…
26:48:900Michele De Carli: you are not asked to make an important design on this point. You… you buy all the machine, inside there is already the tent, and it produces domestic hot water. So…
27:00:270Michele De Carli: for this resource, I didn't mention.
27:03:400Michele De Carli: In all these other systems, you will have to make a…
27:08:840Michele De Carli: a little design. So, let's try to see.
27:12:950Michele De Carli: We start from the systems with storage.
27:16:770Michele De Carli: it's easy. This one is a direct heat up with a gas boiler, so inside there is the flame, and then the water tank is heated. Inside this tank, there is already the…
27:32:550Michele De Carli: The domestic hot water that then flows
27:36:00Michele De Carli: to the different fixtures. You can have the same concept with electricity, so a resistance that heats up the domestic hot water. We will see later an example of these two,
27:49:170Michele De Carli: systems?
27:51:550Michele De Carli: And if we move to the instantaneous production, we have exactly the same, so with gas and we have with electricity, but in this case, you will have, that…
28:04:140Michele De Carli: The water is heat up, in… without a lower volume of water, without a tank, but you will enter the water, you will have the water entering, inside,
28:20:320Michele De Carli: With the instantaneous production, so requiring a higher power compared to this one.
28:29:540Michele De Carli: This is the easiest way, so with gas or with electricity.
28:37:670Michele De Carli: the indirect one.
28:40:170Michele De Carli: As different layouts, as you can see.
28:43:380Michele De Carli: The first one is this, an immersed heat exchanger. So, you have that
28:50:760Michele De Carli: Here you have your production system, that can be a gas boiler, that can be whatever you want, and you have a hot,
28:59:690Michele De Carli: Fluid, that can be the smoke exiting from the gas boiler, that can be some other water, and here you have an immersed heat exchanger.
29:11:10Michele De Carli: the same… Happens in this, second…
29:16:120Michele De Carli: system, where you have an external heat exchanger. So, in this case, you have a recirculation pump with a tank that… where the domestic hot water is stored, and then you have the heat exchange that happens only,
29:32:500Michele De Carli: And, on the paintings.
29:37:10Michele De Carli: On the other side, you have the instantaneous production.
29:41:520Michele De Carli: I want to show you that the difference between this one and this one is that, in this case, your purpose is to keep this in temperature, okay?
29:51:500Michele De Carli: And you can do it with lower heat exchange here, while here, you will have… you will need a very high exchange and a very high latency.
30:02:800Michele De Carli: On these two parts, or very high flow rates on the part of the…
30:09:750Michele De Carli: supply, the heat supply. So, the problem in this case is related to the, heat exchange that comes in this, in this, in this vacant exchanger.
30:22:410Michele De Carli: And you know that the higher heat exchange means higher surface, so probably you will need also in that case of a plate heat exchange and much higher surface.
30:34:400Michele De Carli: I hope we have the Israeli.
30:37:480Michele De Carli: The last one, last solution, is this solution when you, are not accumulating, not storing domestic hot water, but you're storing technical water, you will have that domestic hot water comes, enters here, and through a heat exchanger.
30:54:370Michele De Carli: 10 is delivered to the building, which is the main advantage of this solution. You
31:01:90Michele De Carli: are lowering the risk of retrondia, because you are never watered… the water is never,
31:09:490Michele De Carli: stored, and,
31:12:980Michele De Carli: blocked inside a volume of water, but you have that the water that you are using is always flowing when it is required. So, it's…
31:26:130Michele De Carli: A lower volume of water, that is.
31:30:750Michele De Carli: Stagnating inside the pipes.
31:33:430Michele De Carli: So these are more or less all the… approaches that we can use to prepare domestic altuda.
31:44:110Michele De Carli: Any questions? Yeah? In the case with the storage, is it possible to integrate with a solar thermal collector? Yes, this is the best solution in order to
31:58:110Michele De Carli: You have usually all these solutions, so you have sometimes the possibility of putting a different hybrid and different heat exchangers, okay, and connecting, for example, with a gas boiler, for example.
32:12:640Michele De Carli: And then, for example, here you can have the… another connection with the solar panel connector, yeah. The solar exchanger is on the bottom of the
32:25:600Michele De Carli: Order this notification, yeah.
32:33:130Michele De Carli: Yeah. Instead, it's, maybe, the amount of,
32:41:150Michele De Carli: respect of, respect to, Well, for whatever year tomorrow.
32:49:150Michele De Carli: Respect to this, sorry.
32:50:960Michele De Carli: We need a lot of,
32:53:160Michele De Carli: much hot water. So, is the weather… is that concern from our risk?
33:01:340Michele De Carli: now I try to… with the next slide, I try to… to give you an answer.
33:07:250Michele De Carli: Okay.
33:09:860Michele De Carli: Mainly the… how the heat is released depends on the system you use to provide, provide heat.
33:21:30Michele De Carli: For example, this is a solution for a… Instantaneous gas boiler, okay.
33:31:530Michele De Carli: You can see here, we don't have the tank, okay? But, for example, you have a plated exchanger where the heat exchange happens, okay, and it is always provided with constant flow rate and a constant temperature. So, yeah, the power in this case is constant, but it depends on the situation.
33:51:330Michele De Carli: With the heat pumps, it is not constant, for example. If you have an heat pump that produces heat, it is not constant. If you have a connection with the solar thermal connectors.
34:01:880Michele De Carli: collectors, it is not constant, because it depends… the temperature of the fluid entering the tank depends on how much the sun can hit the…
34:13:650Michele De Carli: the connectors.
34:16:150Michele De Carli: Is it clear? No.
34:18:580Michele De Carli: More or less, nevertheless. Okay, so you are asking me if the power supply to the tank is constant.
34:27:230Michele De Carli: For example, here, if it is constant, the power supplied by the electrical resistance
34:33:370Michele De Carli: Yeah, if I have an electrical resistance, yes, it is constant, because I have that electrical resistance. If I don't modulate the resistance, it is constant to the power.
34:42:360Michele De Carli: In this case, with the flame, it is constant, because I can assume that the gas has a constant flow rate, it burns, and then it gives you a constant flow rate. Otherwise, I can also modulate the gas, but then it depends on the
34:58:490Michele De Carli: Usually, in gas boiler system, it is constant.
35:03:940Michele De Carli: I've been doing… A container, it's okay with storage, but for days, that is responsible.
35:09:850Michele De Carli: For the instantaneous one.
35:11:560Michele De Carli: Yeah, usually it is constant, then it has an internal control that modulates the flame when the temperature is next… is close to the set point.
35:23:910Michele De Carli: Okay.
35:26:490Michele De Carli: Yeah, but you usually use… this is the question… you usually use the tank with the gas provider for large applications. Yeah. It is in case you provide domestic control type in each U.S.
35:41:40Michele De Carli: But you might have also… Central heating system.
35:46:630Michele De Carli: In particular houses where we have pragmatic, Okay, produced.
35:56:110Michele De Carli: Finish, like… So, that's that opportunity.
36:05:300Michele De Carli: Okay, two examples, and then we move to the sizing.
36:10:520Michele De Carli: This one is… a That's brought in many of you, as…
36:17:230Michele De Carli: at your home. This is a glass boiler for instantaneous domestic automotive production.
36:26:310Michele De Carli: This is the layout that, more frequently, you find.
36:31:100Michele De Carli: So, this is used for both the radiators and the domestic hot water.
36:38:300Michele De Carli: You have two circuits inside this. You can see that this one is the technical water circuit. This circuit, usually is connected to the rocketos, or to the dragon system, if we are talking about a condensing spoiler.
36:57:930Michele De Carli: It's a possibility that, especially in the last years, it's not used anymore.
37:05:100Michele De Carli: So, here you will have water coming from the up… from the closed loop. Here, you have to think that in this part, there are the radiators.
37:14:950Michele De Carli: And then it's a closed loop, so the water entering from the closed loop, It is pumped inside.
37:22:830Michele De Carli: this boiler inside this combustion chamber. Here you have the gas and the combustion that happens on the upper part, sometimes on the outer part, it depends on the layout. You can find many different layouts. And then, water.
37:40:290Michele De Carli: is heated inside the combustion chamber by the direct flame and by the smokes, and then it is connected to the other rotators. So this is the closed loop for…
37:55:110Michele De Carli: the… Heating system of the radiators for the technical, water heating.
38:03:460Michele De Carli: What happens if I ask my shower to open, so I open the shower with hot water.
38:12:480Michele De Carli: There is a priority valve that is acting. So, in this case, this priority valve closes this branch.
38:21:610Michele De Carli: And open this part, so the water…
38:24:880Michele De Carli: make this path. When it arrives here, it enters the plate heat exchanger. And then, after making the heat exchange, it takes it here.
38:37:460Michele De Carli: And then, goes in this part. Sorry, I.
38:41:20Michele De Carli: told something that is not appropriate. Of course, the pump is here, so the path becomes this one. Water cold enters inside the combustion chamber. Here, the priority valve send it this part, this way, and then the loop is this one.
38:59:280Michele De Carli: So, the part excluded is the part of the radiators, of course. When you are making very long showers during winter nights, you will exit the shower, and you will find the colder radiators.
39:14:660Michele De Carli: Because your priority valve has closed, excluded the radiator part.
39:20:970Michele De Carli: In this plate heat exchanger, it happens the,
39:26:870Michele De Carli: Heat up of domestic hot water, the cold water comes from the aqueduct, enter the plate heat exchanger, and then exit.
39:36:500Michele De Carli: In this case, these systems usually are described in technical data sheet with power, a constant power, that is the peak power they can provide with a flame, for example, 20, 25, 30 kilowatts, and this is what you choose. You decide which is
39:56:230Michele De Carli: the power needed for the domestic hot water vibration and for the heating system. You choose this system that makes both for you.
40:08:450Michele De Carli: Any question about the behavior of this?
40:12:210Michele De Carli: System? No?
40:15:210Michele De Carli: It's quite easy.
40:16:740Michele De Carli: But I want to show you also a second example.
40:20:200Michele De Carli: This is, probably you know the company that produces this. These are electric boilers for instantaneous production. It is not really only instantaneous, sorry for the data sheet, it is in Italian, I will try to translate it and upload the
40:39:460Michele De Carli: The presentation, you can see that there is also a minimum capacity, so there is a little boiler inside, 10 liters, 15 liters, 30 liters. That is very low capacity, but in this case, with 1 kilowatt.
40:56:780Michele De Carli: or 1.5 kilowatts of electrical resistance, you will have the possibility of buying domestic hot water, in which solutions? Of course, not for your shower, not in one house, but for example, we can have it, for example, when you have
41:12:430Michele De Carli: offices or places where you have a bathroom. You have to provide hot water to sinks, for example, and you only have one sink
41:21:70Michele De Carli: Inside, and so you take this and you put above the sink that provides only hot water for that sink.
41:28:990Michele De Carli: In fact, the installation here, it's mentioned in this line, is above the sink.
41:36:290Michele De Carli: There are also bigger ones that are placed below the sink with higher volumes. It depends on how many sinks you have to connect, so this is a possible solution. When you have really low amount of domestic hot water, it must be ready. When you go to the bathroom, you need to
41:54:910Michele De Carli: wash your hand, you need instantaneous hot water. This solution is a good solution. It's not only instantaneous, but it mixes instantaneous production with
42:05:810Michele De Carli: meets, with a tank, with a little tank.
42:10:880Michele De Carli: Okay.
42:16:340Michele De Carli: I know that, you have already seen this slide.
42:22:310Michele De Carli: But now, we are going more into detail about the sizing of this.
42:32:550Michele De Carli: System, sir?
42:34:170Michele De Carli: we will,
42:39:110Michele De Carli: You have a cold now?
42:52:210Michele De Carli: Okay.
42:57:870Michele De Carli: They are hugging me.
43:01:550Michele De Carli: Alright, okay, so now we… We try to…
43:09:820Michele De Carli: understand how to size a system. In the case of instantaneous production, we have partly already seen it. Once you calculate which is
43:21:870Michele De Carli: the power you need, you can decide which is the system, the gas boiler, for example, that you are required to buy in order to supply this.
43:32:290Michele De Carli: The more complicated aspect is the one related to the storage.
43:38:290Michele De Carli: So, I will make a focus only on this
43:43:470Michele De Carli: system that is the one with the mixed hot water storage system.
43:49:590Michele De Carli: I will make a focus on this, and will provide you the equation for both this solution and the one with the inverse heat exchange.
44:02:650Michele De Carli: So, by analyzing this system, I will go very fast in this part, from the thermodynamic point of view, you know that you have a water volume.
44:12:610Michele De Carli: And in this water volume, the internal energy variation of the system, that is the one, this one, described in particular by the variation of the temperature of the water inside over the time.
44:27:690Michele De Carli: This energy variation depends on the heat balance, on the heat fluxes that are entering and exiting from this tank. So we make the energy balance, and we know that this
44:43:420Michele De Carli: Is the heat released by the…
44:46:250Michele De Carli: heating system. It can be anything fluid, but it can be also a constant electrical resistance, it can be a…
44:55:770Michele De Carli: I don't know, because it can be the exchanger of the heat pump, the condenser of the heat pump.
45:03:600Michele De Carli: This is the heat flux used to provide heat to the tank.
45:10:210Michele De Carli: And then another flux is the one related to the water entering and exiting. In the mixed hot water storage system, when you open your sink or your shower, you will have that specific
45:29:460Michele De Carli: Fluorate is exiting, the one that you require, and simultaneously, the same, for the continuity, the same water flow enters the
45:42:660Michele De Carli: Mixed hot water, hot water storage system, and the temperature of the aqueduct, and it mixes with all the volume.
45:52:570Michele De Carli: So, the energy flux that is exchanged with this flow rate can be described by M, that is the same for both the cases, CP of the water, and the difference between the temperature
46:10:660Michele De Carli: of the supply and the temperature of the output. And this is the second term.
46:21:80Michele De Carli: pay attention to the signs. Here you have minus, and here you have plus, because
46:28:630Michele De Carli: In this case, we are making the balance of which flows, energy flows, are entering the tank, so…
46:36:100Michele De Carli: to the right part of the equation, all the flows that are entering will have positive sign, the QS is entering, so will have positive sign, while all those that are exiting have negative sign.
46:51:220Michele De Carli: Another element, another component of this thermal balance is the losses through the envelope.
47:00:40Michele De Carli: A, S, B.
47:03:110Michele De Carli: We will know this equation from the previous course of feed transfer, so…
47:08:90Michele De Carli: Probably. You know it much better than I do.
47:14:530Michele De Carli: Which is the problem. The problem is that we have…
47:18:20Michele De Carli: Here, a differential equation. So, how can we solve this differential equation?
47:24:460Michele De Carli: We have to enter into the logic of time.
47:28:800Michele De Carli: And…
47:30:650Michele De Carli: And this is one of the most difficult aspects of preparing… of working with the vesicle theater production. So.
47:39:300Michele De Carli: There is a difference.
47:44:70Michele De Carli: Between… Or better. It is important to have a difference between the time When the water is required.
47:54:290Michele De Carli: And the time in which we provide the heat.
47:58:860Michele De Carli: If… I… us.
48:03:500Michele De Carli: for money.
48:04:920Michele De Carli: To my lawyer, to provide me
48:08:140Michele De Carli: 0.15 liters per second of water at high temperature, with its related enthalpy flux.
48:17:90Michele De Carli: There is the possibility that my system, this is the concept of
48:21:310Michele De Carli: the storage. My system does not provide me that heat in that time, but it provides it at a lower rate, but with a longer time.
48:33:900Michele De Carli: And this is the concept.
48:36:380Michele De Carli: of the storage. So, we can distinguish
48:40:360Michele De Carli: Between a preheating time and a supply time.
48:46:260Michele De Carli: With a timeline here on the right, it's much easier. So let's imagine that we have
48:52:660Michele De Carli: Just install the system.
48:55:220Michele De Carli: The volume is at a low temperature.
48:58:430Michele De Carli: we switch…
48:59:870Michele De Carli: on, in this point, the production of heat. The temperature rises until the maximum temperature. In this part, it is switched off.
49:13:300Michele De Carli: And then we have the supply time in which the Water.
49:21:360Michele De Carli: Is asked from the user.
49:25:780Michele De Carli: And, for example, from this solution, we have that we switch on, we open the sync.
49:32:960Michele De Carli: valve, and then hot water is exiting, and this exiting with the simultaneous inlet inside the tank of the cold water, and so we will have that the temperature inside will be lowered by the cold water that enters the tank.
49:53:260Michele De Carli: Why do you distinguish between the preheating time and the supply timer?
49:58:160Michele De Carli: Because in this way, we can solve the differential equation before.
50:02:740Michele De Carli: So, we have that the heat losses will be divided into the heat losses during the preheating phase, and the heat losses during the supply phase.
50:18:370Michele De Carli: P stands for preheating, and D for demand.
50:26:70Michele De Carli: How to calculate the losses? Always the same way. KS temperature difference.
50:35:30Michele De Carli: which is the difference between the preheating and the supply. The difference is that in the preheating time, the average temperature inside the tank will be the one
50:50:50Michele De Carli: the arithmetic mean between the starting one and the maximum one. So, in the preheating time, the average between these two can be assumed as a
51:03:560Michele De Carli: An average temperature.
51:07:40Michele De Carli: We used to calculate the heat losses.
51:09:240Michele De Carli: During the supply time, the losses will be
51:13:790Michele De Carli: Calculated with another average temperature between the maximum and the, the final
51:22:280Michele De Carli: The user temperature, the temperature at each.
51:26:140Michele De Carli: Leo adrequinosta.
51:29:180Michele De Carli: Pay attention that this Temperature.
51:33:510Michele De Carli: Can be used in this equation, only because we're making a sound.
51:38:300Michele De Carli: We make an assumption that At the end of the delivery of water.
51:44:840Michele De Carli: The tank has reached the minimum possible temperature, that is, the water required.
51:52:950Michele De Carli: by names.
52:00:610Michele De Carli: I try to explain it more clearly.
52:05:340Michele De Carli: You will assume that this supply
52:09:220Michele De Carli: We last for several hours, for example, during the evening.
52:13:790Michele De Carli: you are all making the shower between 6 and 8. So, we will assume that our supply time will be 2 hours, between 6 and 8. We will assume that
52:26:500Michele De Carli: All the uses of domestic hot water will be due by the user in that amount of time.
52:34:550Michele De Carli: And after those 2 hours, in which we have used as much hot water as we can, the maximum for that family.
52:43:890Michele De Carli: For that building, At the end, we will have reached the temperature QU inside of the tank.
52:51:340Michele De Carli: It means that if, at 8-1 minute, I open a sync, okay, after I have used it a lot.
52:59:460Michele De Carli: The water does not exit the sink at this temperature, but at a lower temperature, because I have used all the hot water I have inside.
53:09:590Michele De Carli: It starts to… exit at lower temperature. How to avoid this risk?
53:16:710Michele De Carli: we usually…
53:20:980Michele De Carli: We usually use the worst case scenario, and so we overestimate the use of domestic hot water in order not to finish the hot water inside the tank.
53:34:720Michele De Carli: So, if we integrate this equation, M.
53:44:360Michele De Carli: the preheating time.
53:49:910Michele De Carli: And in the total, Proheating blossom.
53:55:70Michele De Carli: Delivery, we will obtain these two equations.
54:00:190Michele De Carli: For the mixed hot water storage system.
54:03:630Michele De Carli: And these two equations will be the two equations that we will use To size the system.
54:16:350Michele De Carli: The losses, thermal losses, that are these ones, will be calculated according to Two or two web simplicity.
54:24:910Michele De Carli: Here you have the terms for your time for storage.
54:30:480Michele De Carli: The variation of energy inside of this knowledge.
54:35:240Michele De Carli: And here you have the water delivered for the user.
54:40:570Michele De Carli: And here, they heat up.
54:46:930Michele De Carli: Just a clarification, wide enough.
54:50:180Michele De Carli: in the… Power analysis, the heat, transfer analysis. We used… a flow rate.
55:00:810Michele De Carli: That is the one that we'll use here, for example.
55:05:690Michele De Carli: In this case, we make an assumption of A mass of water used.
55:13:190Michele De Carli: End of a preparation and a delivery time.
55:18:620Michele De Carli: So, we will, Not use it.
55:22:760Michele De Carli: a flow rate as input of this method to size, but we will use
55:28:270Michele De Carli: A mass of water, a kilograms, or liters, of water, Endo.
55:34:830Michele De Carli: A time of preparation and not delivery.
55:47:180Michele De Carli: So, what does it mean to size?
55:49:890Michele De Carli: In domestic hot water storage systems.
55:54:90Michele De Carli: It means that we need to calculate
55:58:710Michele De Carli: The peak power, the thermal power required to heat the system, and the capacity of the storage.
56:08:230Michele De Carli: And in order to do this, we have to assume different parameters.
56:12:670Michele De Carli: Supply time, preheating time, amount of hot water supplied, temperature of the hot water we supply, the temperature of the aqueduct, and the maximum temperature of the water inside the tank after the preheating. That is the set point of the tank.
56:31:800Michele De Carli: In these regulations, the power that we deliver to the hot water is considered constant, so QS will be constant and non-parallel.
56:44:40Michele De Carli: Is it clear until now? Do you have any question?
56:48:120Michele De Carli: Okay.
56:51:380Michele De Carli: These are the two equations I showed you before.
56:54:560Michele De Carli: These ones. While… These ones are for the internal exchanger.
57:01:440Michele De Carli: I won't talk about the theoretical aspects of the internet exchanger, but as you can see.
57:10:590Michele De Carli: Here, the parameters are exactly the same, so we always…
57:16:290Michele De Carli: the amount of water supplied. We always have the losses that are occurring in the same way, and the timing, and whatever, so on.
57:28:320Michele De Carli: So… If you want.
57:31:470Michele De Carli: clarification about this, we can talk about this, Matt, after the lecture.
57:38:370Michele De Carli: Okay, so now we try to, do a fast exercise.
57:48:70Michele De Carli: In order to try to make these calculations and use these equations.
57:52:990Michele De Carli: The text says that we have to size
57:56:90Michele De Carli: A mixed water storage system that must supply 100 kilos of water.
58:04:100Michele De Carli: And so, this is the first.
58:07:340Michele De Carli: parameter.
58:08:470Michele De Carli: we have as input 100 kilos of water at 40 Celsius degrees.
58:14:250Michele De Carli: with a supply time of 1 hour, making the hypothesis that between 6 and 7 PM, we use 100 kilos of water.
58:26:300Michele De Carli: maybe…
58:27:710Michele De Carli: talking about 100 kilos of water is a little bit not clear. You know that the density of water is 1 kilo per liter, so…
58:35:860Michele De Carli: We have… these are 100 liters.
58:41:110Michele De Carli: We assume a preheating time of 5 hours.
58:44:840Michele De Carli: And the maximum temperature in the tank.
58:47:260Michele De Carli: is 60.
58:50:410Michele De Carli: For the calculations. Also, assume that
58:54:620Michele De Carli: the water from the aqued enters at 10 Celsius degrees, The temperature of the room.
59:01:200Michele De Carli: where the tank is installed is 20 Celsius degrees, and for the thermal loss calculation, assume K08 and S
59:11:170Michele De Carli: 1, 1, 3.
59:14:970Michele De Carli: Repeated the calculations, neglect the tank thermal losses.
59:19:740Michele De Carli: So, I will solve the exercise.
59:25:310Michele De Carli: Try to, at least.
59:29:10Michele De Carli: If I manage, hmm?
59:33:410Michele De Carli: Cheer.
59:41:690Michele De Carli: I think that would be conditioned on it.
59:43:910Michele De Carli: It's a great day.
59:48:910Michele De Carli: Yes.
59:51:340Michele De Carli: Duplicates?
59:55:770Michele De Carli: Okay?
00:17:250Michele De Carli: euros.
00:25:90Michele De Carli: Yeah, she's on the buffetone.
00:29:910Michele De Carli: I'm reading it.
00:35:80Michele De Carli: the vendor station, I call it.
00:40:960Michele De Carli: We're never fulfilled, like, okay Go back.
00:59:680Michele De Carli: Okay, so the first point that we try to face
01:02:800Michele De Carli: We start from the thermal losses population.
01:11:10Michele De Carli: That's the number 33.
01:20:210Michele De Carli: For the thermal losses calculation, we calculate the two components.
01:27:610Michele De Carli: The one is the thermal loss during the preparation time.
01:41:620Michele De Carli: K, A, T, medium during the preparation, and the temperature of the environment.
01:48:60Michele De Carli: According to the data we have, We have 093.
01:56:190Michele De Carli: 1.
01:57:200Michele De Carli: 1, 3…
02:02:10Michele De Carli: 35… Minus… 20. Can you zoom a little bit? Yes, I think so.
02:13:530Michele De Carli: Is it okay like this? Thank you, Shibu.
02:19:40Michele De Carli: More than me.
02:24:490Michele De Carli: Let's go, and… now I… I make all the… So…
02:34:720Michele De Carli: K was 0.8, but it was in another unit of measurement. I cannot switch to the presentation, right? No, okay, okay.
02:46:610Michele De Carli: Okay.
02:48:650Michele De Carli: This is in… VAT?
02:53:980Michele De Carli: square meter Kelvin, you will have kilocalories per hour per square meter Kelvin.
03:00:400Michele De Carli: Science degrees.
03:02:160Michele De Carli: Absolutely. Yes?
03:04:960Michele De Carli: 100, liters of water per one hour.
03:14:180Michele De Carli: No, no, no problem.
03:16:430Michele De Carli: This is just an exercise. Doppler, later we will see the parameters for the sizing.
03:26:150Michele De Carli: Hmm.
03:28:770Michele De Carli: Later, we will see which are the volumes of water we're talking about. Yeah. So, when I finish the 100 liters of water, even in 10 minutes? If you size the system for 100 liters, yes.
03:44:670Michele De Carli: Yeah. Then, we are talking about 100 liters hot water.
03:57:250Michele De Carli: You don't know about them.
04:05:910Michele De Carli: Viamo estabale.
04:13:770Michele De Carli: boilitore.
04:32:470Michele De Carli: Go ahead.
04:36:890Michele De Carli: Everything, maybe I just can, according to this point.
04:42:570Michele De Carli: But, I mean, it's up to you, okay? So, as designer, it is up to you how much you want to size, or size, other sizes. Yes.
04:58:970Michele De Carli: Yes, I could also… sorry… Yeah, yeah. I could also mention that…
05:04:70Michele De Carli: You could keep this one hour, one hour, 100 meters, then it depends how long it would take for the…
05:12:840Michele De Carli: To, say, reach the wanted sign that we obtained.
05:19:670Michele De Carli: the preheating time. The preheating.
05:23:880Michele De Carli: Bring… Yup.
05:33:920Michele De Carli: So, this is the calculation of the flow rate.
05:38:520Michele De Carli: over the floor rate. The… It rated.
05:43:520Michele De Carli: And you can see that the losses are 18…
05:46:900Michele De Carli: words. How to calculate this value?
05:50:920Michele De Carli: that these… the… Mean during the preheating.
05:55:920Michele De Carli: It is the maximum.
06:01:300Michele De Carli: And the average, and the… sorry, the environment divided by 2.
06:06:980Michele De Carli: Sorry.
06:07:980Michele De Carli: A is the one from the aqueduct.
06:10:330Michele De Carli: So, this is 60 plus 10.
06:22:430Michele De Carli: This is the temperature used to calculate
06:27:800Michele De Carli: the losses between the preheating time, during the preheating time, so the average between the profile I showed before.
06:42:270Michele De Carli: This is the max loop.
06:44:330Michele De Carli: Who's this one?
06:45:870Michele De Carli: not uses either.
06:47:710Michele De Carli: And the preheating time is this one, so it's the aggregation between one.
06:53:520Michele De Carli: East Coast.
06:57:50Michele De Carli: The water that comes from the apartment, and the maximum water from the tank.
07:04:430Michele De Carli: If we move, To the other one.
07:10:960Michele De Carli: it is 093, I directly go to the Numbers.
07:20:90Michele De Carli: 50 minus… 19.
07:30:890Michele De Carli: 36.3.
07:34:190Michele De Carli: were 50.
07:38:660Michele De Carli: is the temperature.
07:42:480Michele De Carli: Between the maximum.
07:47:570Michele De Carli: And the temperature, TU. Sorry, Izma.
07:52:800Michele De Carli: 60 plus 40.
08:16:850Michele De Carli: The second point, once we have calculated the thermal losses.
08:22:569Michele De Carli: Is to put to the sizing equations.
08:29:69Michele De Carli: That are those that we have seen before.
08:36:120Michele De Carli: For the mixed hot water storage system, The first one.
08:43:430Michele De Carli: It's the one for both the preheating and the delivery time.
08:55:529Michele De Carli: the mass of water delivered, the CP of water, And the temperature difference.
09:04:160Michele De Carli: Between the one exiting to the user and the one coming from the app group.
09:11:830Michele De Carli: the losses, So…
09:21:870Michele De Carli: Each one with its own time.
09:27:560Michele De Carli: And then… the internal variation.
09:35:979Michele De Carli: Internal energy variation.
09:39:20Michele De Carli: The second one… It's the one only for the…
09:46:850Michele De Carli: Delivery time, sorry, the preheating time.
09:50:450Michele De Carli: This is a P.
09:53:750Michele De Carli: Yes, CP.
10:04:960Michele De Carli: Preheating time of preheating.
10:08:480Michele De Carli: These are the two equations.
10:13:560Michele De Carli: And now… what I want to do.
10:17:780Michele De Carli: Is to solve
10:22:800Michele De Carli: in two ways. The first time.
10:27:150Michele De Carli: I will use the international system units of measurement.
10:35:940Michele De Carli: The unknown values are… the heat, the QS value, and the volume of the storage. So, QS…
10:46:500Michele De Carli: The time we have, the delivery time that is 1 hour, and the preheating time that is 5 hours.
10:56:740Michele De Carli: 3,600.
11:04:980Michele De Carli: The liters of water required.
11:07:780Michele De Carli: the CP?
11:11:410Michele De Carli: the delta T, 40 minus 10.
11:16:440Michele De Carli: The loss is 36.3.
11:20:610Michele De Carli: The time is 1 hour.
11:26:20Michele De Carli: The other losses, 18.1.
11:29:720Michele De Carli: 5 hours.
11:31:260Michele De Carli: 3,600.
11:38:910Michele De Carli: And the last one is the volume of the storage.
11:43:740Michele De Carli: 4,186.
11:46:900Michele De Carli: 40 minus.
11:49:970Michele De Carli: Here, the units of measurement.
11:53:270Michele De Carli: Are according to the international system.
11:55:880Michele De Carli: So this will be… In water?
11:59:490Michele De Carli: This in our, and this… The second in one hour.
12:06:970Michele De Carli: Here, kilograms.
12:10:250Michele De Carli: Joule per kilogram per Kelvin.
12:13:450Michele De Carli: the Delta T.
12:15:20Michele De Carli: If incurring.
12:17:210Michele De Carli: And so on.
12:25:970Michele De Carli: Also, this one is in kilograms, of course.
12:31:970Michele De Carli: Second equation.
12:35:460Michele De Carli: We have QS, 5. That is the preparation time.
12:44:100Michele De Carli: 3,600, the conversion.
12:47:460Michele De Carli: VS… 4,186.
12:52:910Michele De Carli: And the temperature maximum.
12:55:380Michele De Carli: That is 60 minus 10.
13:00:750Michele De Carli: glass?
13:03:370Michele De Carli: the… Losses during the preparation time.
13:08:890Michele De Carli: That is 18.1.
13:13:280Michele De Carli: 5… How was 3,600.
13:29:950Michele De Carli: I also want to show you Praise the law.
13:37:340Michele De Carli: the difference…
13:43:350Michele De Carli: of using Aye the technical units.
13:54:310Michele De Carli: In this case, The calculation will be much easier.
14:13:880Michele De Carli: Is there any question?
14:20:720Michele De Carli: Excuse me.
14:23:570Michele De Carli: Okay, if we use the technical, the technical units.
14:30:480Michele De Carli: You will see that the calculation Will become much easier.
14:57:870Michele De Carli: This is an example of using technical units, because the power, it's in kilocalories per hour.
15:05:780Michele De Carli: And here you will have Only the number of hours you will have to use.
15:10:780Michele De Carli: Also, the volume will be calculated in liter.
15:14:420Michele De Carli: DCP, is one… Because it is in kilocalories, Per kilogram, per se degree.
15:30:440Michele De Carli: I'm always using, in these assumptions, in this calculation, the,
15:38:950Michele De Carli: It's obvious that we are using Kilograms and liters
15:44:320Michele De Carli: In the same way, because the density is 1, so…
15:48:310Michele De Carli: This is why you can see here kilograms and here liters.
15:53:290Michele De Carli: If we want to be rigorous, we should also put inside the equation the density that is 1 kilogram per liter.
16:01:970Michele De Carli: So also here, we have kilocalories per hour.
16:05:470Michele De Carli: And here we are 1 hour.
16:08:520Michele De Carli: And so on. So, using technical units can allows you to solve the equation also without using the calculator, because it becomes really easy.
16:20:470Michele De Carli: The second one is exactly the same. Multiply 5… VS multiplied 160 minus 10.
16:31:160Michele De Carli: plus 18.1.
16:33:970Michele De Carli: Multiply. 5.
16:38:50Michele De Carli: So, this is the writing down of the equations using both the international system And the technical units.
16:49:860Michele De Carli: the last passage, and then I move to the final part of the lecture.
16:57:150Michele De Carli: Is the solution.
17:09:70Michele De Carli: So, if we consider the thermal losses.
17:18:720Michele De Carli: the storage volume, Will be 100.5 kilograms.
17:27:150Michele De Carli: and the QS, will be.
17:30:690Michele De Carli: 1021 kilocalories per hour.
17:35:170Michele De Carli: That means… 1… 1… 8, 7, well.
17:41:490Michele De Carli: Something more than 1 kilowatt.
17:48:800Michele De Carli: without… Losses.
17:53:710Michele De Carli: The volume will be 100 kilos.
17:56:970Michele De Carli: and QS.
17:59:930Michele De Carli: 1,000 kilo.
18:02:530Michele De Carli: Can't already split up.
18:11:920Michele De Carli: If you solve the above equation, you will find this solution.
18:15:560Michele De Carli: So, what is important?
18:18:100Michele De Carli: Is to see that considering, or not considering, the losses
18:24:360Michele De Carli: It simplifies a lot the calculation, but it won't affect
18:30:30Michele De Carli: the solution, because the losses are of an order of magnitude. We are talking about 30W, 40W, compared to 1 kilowatt of production. That is.
18:40:980Michele De Carli: An order of magnitude of difference.
18:44:30Michele De Carli: Much more than one other apartments. So…
18:46:870Michele De Carli: We are talking about two different orders, and so considering or not in the calculation, the losses is always something that doesn't take into the machine.
18:57:190Michele De Carli: What is important is not to calculate the losses adequately, but it is to make the correct assumptions that we will know.
19:05:320Michele De Carli: We get it?
19:10:750Michele De Carli: I will upload this file on Google.
19:20:900Michele De Carli: Right?