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00:01:800Jacopo Vivian: Okay? So on, Moodle, you find the description of the report, which is this document here.
00:09:160Jacopo Vivian: with the parts that you need to include in the report.
00:13:250Jacopo Vivian: and this year we don't have the ventilation, because you already have the group work on the ventilation on the full air system.
00:24:540Jacopo Vivian: And also we don't have the hydronic part.
00:28:850Jacopo Vivian: But we have this part here. Number 7.
00:33:200Jacopo Vivian: So you need to calculate the heat capacity at design condition. Okay, which is a
00:45:930Jacopo Vivian: looking at the, at the catalog of a heat pump that you select.
00:51:750Jacopo Vivian: Whatever manufacturer is. Okay. You just luke
00:56:870Jacopo Vivian: for a heat pump catalog online.
00:59:860Jacopo Vivian: Okay?
01:01:370Jacopo Vivian: And you make sure that the design that the
01:07:980Jacopo Vivian: power thermal power that this heat pump
01:11:910Jacopo Vivian: that you select is okay for your case study.
01:16:760Jacopo Vivian: Okay, you specify whether is heating only or heating and domestic hot water.
01:25:700Jacopo Vivian: You specify how you calculated the thermal power in design conditions.
01:36:20Jacopo Vivian: And that's it.
01:39:732Jacopo Vivian: Yeah, there is not much you just need to. And of course you upload the
01:47:320Jacopo Vivian: I don't know you insert this inside the record so that they can usually check the catalog
01:57:250Jacopo Vivian: like a screenshot with the name of the model of the heat pumper and the heat capacity. And
02:09:110Jacopo Vivian: okay, is that clear? Or is there something.
02:17:600Jacopo Vivian: So the the only thing that you need to check basically is that the
02:23:590Jacopo Vivian: since in the catalog you don't always have
02:28:170Jacopo Vivian: the thermal power exactly at design condition.
02:32:970Jacopo Vivian: You use some method like regression in case you don't have that value
02:39:760Jacopo Vivian: to. To estimate the thermal power that this heat pump can deliver at the design condition.
02:48:490Jacopo Vivian: Okay, this is what I showed.
02:53:30Jacopo Vivian: Yes, definitely.
02:55:990Jacopo Vivian: For example, if you have a point at 7 Celsius degrees and a point at 2 Celsius degrees.
03:03:60Jacopo Vivian: If your design condition is at minus 5, you need to estimate the thermal power that the heat pump will deliver at minus 5.
03:13:690Jacopo Vivian: Okay, okay?
03:18:700Jacopo Vivian: So let's start. If you don't have questions, I start with a new topic
03:28:640Jacopo Vivian: which is district heating and cooling systems.
03:32:800Jacopo Vivian: Am I sharing the screen.
03:39:590Jacopo Vivian: Yes.
03:48:540Jacopo Vivian: I hope.
03:50:840Jacopo Vivian: Okay. So district heating and cooling systems are systems that have that are big hydronic systems. Okay? So everything that we have seen on the building level applies also for district heating and cooling systems because they use in most cases, heat sorry water as a heat carrier fluid.
04:15:60Jacopo Vivian: They are networked systems.
04:18:789Jacopo Vivian: Unlike natural gas which is coming from abroad. It is a local system. Okay? So we don't have a transnational pipelines of district heating. We only have
04:35:380Jacopo Vivian: district heating at urban level, basically in 99.9 9% of the cases
04:44:420Jacopo Vivian: they can provide the heating or cooling, or both.
04:49:60Jacopo Vivian: Okay, so, depending on how they are designed.
04:54:350Jacopo Vivian: they are public infrastructures. In most cases
05:00:50Jacopo Vivian: the only case where they are not public is at least in my experience, industrial areas
05:10:490Jacopo Vivian: where they can be also owned by private entities.
05:18:600Jacopo Vivian: but they are always subject to and public regulation, of course.
05:26:500Jacopo Vivian: so they are in most cases public infrastructures, and therefore they need, in order to be realized that they need political action. So we don't have districting systems in all cities because there were not the same.
05:49:230Jacopo Vivian: people governing this.
05:51:980Jacopo Vivian: All these all the cities. Okay. So each admin city administration is responsible for the infrastructure of a certain city where it governs. So if the administration is not
06:10:122Jacopo Vivian: does not think that this infrastructure is important. You don't find this infrastructure, and it. It takes a long time to build it.
06:22:500Jacopo Vivian: Okay? Because from the moment where you start the designing the network. Think where it can go where it can be installed.
06:35:340Jacopo Vivian: Communicate this to the citizenship, make this decision approved, start making the public tender, make some private companies win the tender start delivering the project started constructing it. It takes many years. Okay, so maybe you start today and the
07:03:58Jacopo Vivian: you start this process today and the 1st pipe will be buried in the ground in 7 years. So you don't have a political
07:13:820Jacopo Vivian: recognition for this infrastructure the day after this is why in
07:21:670Jacopo Vivian: Often it has not been built.
07:25:470Jacopo Vivian: and also it has. It is a.
07:29:10Jacopo Vivian: of course, a competitive infrastructure against gas networks, because if you are not
07:38:432Jacopo Vivian: providing heat. They are meant to provide heat. But today we have a capillary gas network reaching
07:46:120Jacopo Vivian: every building, at at least in the valley and in the north of Italy. But nowadays
07:55:230Jacopo Vivian: the gas network is reaching apart from mountain regions where you don't have gas network in the in most places in Italy you have the gas network. So it is a strong compete.
08:15:550Jacopo Vivian: There is a competition between
08:18:320Jacopo Vivian: gas supply and district heating network.
08:23:949Jacopo Vivian: What is the advantage of the network? Why should we look more into these systems because they are able to recover heat from local sources and from renewable energy sources.
08:38:210Jacopo Vivian: And today I will show some examples of this also environmental
08:48:30Jacopo Vivian: how they are made. They are made by a supply station or more supply stations.
08:54:860Jacopo Vivian: Okay, where you have the generation systems.
08:58:550Jacopo Vivian: then you have the distribution system which is
09:04:30Jacopo Vivian: made by transmission pipes and service pipes. So service pipes are the final branches reaching each single
09:17:220Jacopo Vivian: building. Okay? So the service pipe is made for a specific building.
09:26:300Jacopo Vivian: The transmission pipe is made to serve more buildings.
09:31:760Jacopo Vivian: and in each. In each building connected to a district heating network there is a substation.
09:38:770Jacopo Vivian: The sub. The substation receives the the service pipe supply, a return
09:48:270Jacopo Vivian: and there is a a heat exchanger normally.
09:54:450Jacopo Vivian: that transfer the heat from the network to the heating system of the building.
10:02:530Jacopo Vivian: Okay? And then I will show you how they are actually a layout of a substation.
10:10:460Jacopo Vivian: What is the advantage I was telling before?
10:15:480Jacopo Vivian: This is a
10:20:330Jacopo Vivian: These figures said that are Italian. I think Italian figures so
10:30:150Jacopo Vivian: you can see that since we use a lot of cogeneration systems
10:37:11Jacopo Vivian: supplying heat to district heating networks.
10:40:670Jacopo Vivian: we are able to to reduce the primary energy consumption
10:48:180Jacopo Vivian: of by using district heating instead of using a separate production of thermal energy and electrical production.
10:59:210Jacopo Vivian: And the same holds true for for co, 2 emissions, of course.
11:08:604Jacopo Vivian: The more we integrate also renewable energy sources, and not only congeneration unit, the better it is for both, and especially for Co. 2 emissions
11:23:210Jacopo Vivian: who are the typical users in Italy.
11:27:734Jacopo Vivian: Mostly residential users. Okay and tertiary meaning civic buildings like
11:40:620Jacopo Vivian: schools, hospitals, municipality, administration offices, and also we have.
11:49:230Jacopo Vivian: and a small but not negligible part of industrial customers.
11:55:370Jacopo Vivian: Okay, this is in terms of millions of cubic meter of building heated. Okay, so
12:07:180Jacopo Vivian: if you have a building
12:10:610Jacopo Vivian: like this, you would require you need to count for every cubic meter of this building, and it would sum up to this if it is heated with the district heating network.
12:23:290Jacopo Vivian: And this is in terms of energy of thermal energy.
12:28:910Jacopo Vivian: Okay.
12:35:60Jacopo Vivian: so residential accounts for more than 60% of the heat delivered
12:44:500Jacopo Vivian: and tertiary buildings are typically public buildings.
12:51:230Jacopo Vivian: and they are particularly important, although their share is lower than 50%, because they are
13:00:490Jacopo Vivian: super important for the
13:05:340Jacopo Vivian: I'd say for the financial sustainability of the infrastructure. Why? Because when you build the district heating network. You need to have customers from day 0.
13:20:940Jacopo Vivian: So from the moment where the infrastructure is finished, it is built from the day after you need to connect some customers and deliver, start to deliver heating. Otherwise you don't pay back the investment.
13:38:310Jacopo Vivian: Okay?
13:39:480Jacopo Vivian: So since it takes time for private customers to
13:47:770Jacopo Vivian: convince and make the choice to connect.
13:52:240Jacopo Vivian: And we don't always have pipes around the corner. Okay.
13:57:20Jacopo Vivian: then we need some public buildings to connect. From the very 1st time that the network is is built. That's why we're tertiary buildings are very important. Okay?
14:14:580Jacopo Vivian: So
14:16:220Jacopo Vivian: how were these infrastructure born? They were born actually in the West, in big cities, in at the end of 19th century.
14:28:730Jacopo Vivian: with a goal of reduce reducing pollution because
14:33:90Jacopo Vivian: there were a lot of coal boilers
14:36:610Jacopo Vivian: in big cities. And in that case they started building steam networks.
14:45:300Jacopo Vivian: Okay, that the
14:48:50Jacopo Vivian: had the steam basically as a in the supply line and the condensed water in the return line.
14:58:493Jacopo Vivian: Of course, this problem is, is quite I mean, this kind of technology is quite old fashioned. Okay.
15:08:700Jacopo Vivian: there was a problem of steam leakage.
15:11:930Jacopo Vivian: huge heat losses because they were not even insulated corrosion of the front due to the
15:19:900Jacopo Vivian: and condense it. Okay? And so on.
15:24:330Jacopo Vivian: So.
15:26:780Jacopo Vivian: An example of this 1st generation of district networks is the steam that comes out.
15:36:990Jacopo Vivian: If you look at some movies
15:41:918Jacopo Vivian: that are set in New York. You know that there are these
15:48:460Jacopo Vivian: steam sometimes in in the streets, and this is this is coming from the district heating network of of New York.
16:01:260Jacopo Vivian: Okay?
16:04:190Jacopo Vivian: Good.
16:05:120Jacopo Vivian: I don't want to lose my
16:10:300Jacopo Vivian: change.
16:18:290Jacopo Vivian: Okay?
16:22:360Jacopo Vivian: I hope I solve the problem.
16:40:140Jacopo Vivian: Okay, the second generation was
16:44:896Jacopo Vivian: in the ur assess, okay, was made to basically to distribute the heat.
16:54:250Jacopo Vivian: And it came from the necessary, from the, from the opportunity of dissipating the waste heat from the factories in the
17:09:920Jacopo Vivian: you are assess. Okay?
17:12:700Jacopo Vivian: In the
17:14:869Jacopo Vivian: In that case the pipes were not sized according to the demand of the buildings.
17:22:839Jacopo Vivian: but the pipes were sized according to the heat that should be wasted from the factories, and they were distributed to the building. Whatever they had they distributed to the building. In this case the heat carrier fluid was a superheated water.
17:42:60Jacopo Vivian: So water at the not superheated.
17:52:480Jacopo Vivian: It was a pressurized water.
17:56:880Jacopo Vivian: Okay, at the temperatures higher than 100 Celsius degrees. Okay?
18:07:220Jacopo Vivian: So in this case, the also the regulation was that was aimed at dissipating the heat.
18:17:750Jacopo Vivian: So it was production rate driven.
18:21:180Jacopo Vivian: and there was no thermal insulation of the pipes. They were still not the efficient.
18:29:610Jacopo Vivian: Then, in the seventies, sixties, seventies, especially after the energy crisis of 1973, some Scandinavian countries started introducing some efficiency measures to district heating systems.
18:49:380Jacopo Vivian: So in this case, the
18:54:863Jacopo Vivian: the water was at 90. The supply was at 90 degrees with the return design at 60 degrees at the design load.
19:07:540Jacopo Vivian: and you start having insulated pipes and particularly pre-insulated pipes.
19:16:340Jacopo Vivian: Okay?
19:17:570Jacopo Vivian: And also you have a demand driven regulation.
19:21:890Jacopo Vivian: And then I will show you some
19:24:830Jacopo Vivian: an example of how to regulate the district keeping network.
19:32:615Jacopo Vivian: Later on, in the last 10
19:36:720Jacopo Vivian: 10 years, I would say, yes, 1015 years
19:41:847Jacopo Vivian: also from Scandinavian countries, you have the further reduction of temperatures. Okay.
19:49:780Jacopo Vivian: they increase the supply of renewable heat in the energy mixer
19:56:190Jacopo Vivian: and the use of twin pipes in the distribution lines, not in the bigger pipes
20:03:710Jacopo Vivian: in the bigger transmission pipes. But in the smaller branches you can use twin pipes.
20:11:20Jacopo Vivian: I would show sketch later
20:15:330Jacopo Vivian: and recently. You also have this concept of a that is, some sometimes called 5th generation district eating good.
20:24:680Jacopo Vivian: which is different from the previous ones, because in the previous ones you only supply heating.
20:31:540Jacopo Vivian: In this case you have. You don't have a a central supply station with the bigger generation systems.
20:43:40Jacopo Vivian: but you have a natural temperature loop.
20:48:900Jacopo Vivian: and in this in the substations you have reversible heat pumps that can either extract heat from the loop or reject heat into the loop.
21:01:140Jacopo Vivian: In this way the loop can provide, at the same time heating and cooling. And of course, this heat should be somehow extracted from a source or rejected to an external sink. Okay?
21:19:180Jacopo Vivian: And so typically we either use the air or the ground for those kind of of loops. So
21:32:500Jacopo Vivian: here the concept is completely different from the 4th from the previous generations, because it is meant to supply buildings
21:44:950Jacopo Vivian: with better characteristics. Okay, better insulation. And it is aimed at maximizing the amount of renewable heat, renewable heating and cooling.
22:01:370Jacopo Vivian: Here you can see there. There are not many of these systems in operation.
22:07:930Jacopo Vivian: and they are mostly concentrated in Germany, Switzerland, and in North Northern Europe.
22:26:150Jacopo Vivian: So going back to usual, so traditional district hitting network
22:32:70Jacopo Vivian: is the one of the most important indicators in the preliminary analysis of these systems is the so-called linear energy, linear heat density.
22:48:230Jacopo Vivian: which is the ratio between the heat that is
22:54:550Jacopo Vivian: can be delivered to the buildings divided by the network length
23:01:120Jacopo Vivian: of the transmission pipe that we need to have to reach those buildings. Okay.
23:07:880Jacopo Vivian: so we have a certain area of the city.
23:11:530Jacopo Vivian: We estimate by simulations or by energy bills or whatever we we have the energy demands for heating during the year. Okay.
23:25:150Jacopo Vivian: and the overall energy demand of those building, divided by the length of the network that reaches those building is the linear energy density.
23:36:560Jacopo Vivian: Here I put the table with some numbers of the linear heat density for some
23:43:760Jacopo Vivian: networks that we have in the north of Italy.
23:48:120Jacopo Vivian: So we can start from the last one.
23:52:750Jacopo Vivian: which is the biggest network in Italy, the one from Durin. Okay.
24:00:470Jacopo Vivian: here it is also one of the biggest in Europe.
24:05:270Jacopo Vivian: and here you can see they have an overall length of 600 kilometers in the city of Turin.
24:14:860Jacopo Vivian: and the linear energy density of around 3 megawatt hours per meter.
24:20:330Jacopo Vivian: Of course this is possible only in big cities
24:25:300Jacopo Vivian: where we have a lot of big buildings close to each other, so we have a high
24:32:220Jacopo Vivian: density of the heat at the moment
24:35:990Jacopo Vivian: in medium sized cities like those that we have in the northeast.
24:42:480Jacopo Vivian: We have lower numbers. For example, in Vicenza.
24:46:430Jacopo Vivian: Later on I will speak about meetings as network, and also Verona's network.
24:52:130Jacopo Vivian: We have 1.7 in Verona. Okay, Verona is even higher than Turin than Turin.
25:01:282Jacopo Vivian: This is quite strange. And also we have we have 5 networks in Verona. So
25:12:770Jacopo Vivian: it is quite a good good situation, right?
25:17:250Jacopo Vivian: Another but similar city is Ferrara, you see, is similar to Vichenza, so we are below 2 megawatt hour per meter.
25:28:660Jacopo Vivian: and Brescia is the 1st district heating system in Italy.
25:35:380Jacopo Vivian: It's a 2.6 or one of the first, st together with the with the Turin. Okay.
25:44:590Jacopo Vivian: in Asiago we have a district heating network typically in
25:51:220Jacopo Vivian: in mountain regions, we have biomass as main fuel for the district.
25:59:300Jacopo Vivian: So, as a rule of thumb, you have from 0 point 5 to 1.5 megawatt hour per meter in small networks
26:10:760Jacopo Vivian: from 1.5 to 2.5 in medium networks like medium sized cities.
26:18:400Jacopo Vivian: And you have higher than 2.5 in big cities.
26:24:380Jacopo Vivian: Okay?
26:30:460Jacopo Vivian: Of course, the higher the heat, the linear hit the speed the better from a
26:39:80Jacopo Vivian: financial point of view, because you need less investment for the same revenue.
26:51:450Jacopo Vivian: Okay? Because the numerator is proportional to the revenue of the district heating operator.
26:59:210Jacopo Vivian: You said that
27:02:880Jacopo Vivian: the heat that is sold to the customer is proportional to their heated demand, okay? And the denominator is somehow
27:14:148Jacopo Vivian: telling us something about the investment, because the longer the network, the higher the investment needed.
27:22:720Jacopo Vivian: Okay, here you can see how this the investment cost the specific investment cost.
27:32:780Jacopo Vivian: So euros per megawatt hour here
27:37:680Jacopo Vivian: for different networks, how it correlates with the linear heat density.
27:44:370Jacopo Vivian: so lower heat, low heat, density.
27:48:490Jacopo Vivian: I specific investment, high payback time, high heat, density, low specific investment, shorter payback time.
28:05:210Jacopo Vivian: Okay?
28:12:520Jacopo Vivian: And also, it is not only a financial thing. It is also a technical
28:21:480Jacopo Vivian: is also better from a technical point of view, because
28:25:920Jacopo Vivian: the lower the distance, the lower the heat losses.
28:30:60Jacopo Vivian: Okay, of course, this is not so. This is the heat lost depending on the linear energy density.
28:40:390Jacopo Vivian: So on average, you can expect to be around 1015%.
28:52:50Jacopo Vivian: Okay of heat loss.
28:56:430Jacopo Vivian: When is the heat loss important in percentage term?
29:04:100Jacopo Vivian: Do you have any blue during the year?
29:16:430Jacopo Vivian: The heat loss is very important during summer, because you distribute the heat.
29:23:260Jacopo Vivian: because maybe there are some buildings that have a domestic or total demand.
29:28:440Jacopo Vivian: and most of the heat that you distribute is dissipated to the ground.
29:33:250Jacopo Vivian: So if you only look at summer.
29:35:900Jacopo Vivian: the heat loss can reach 50% or even more.
29:42:200Jacopo Vivian: But it is not very important from an energy from
29:47:420Jacopo Vivian: I mean, it is important. But
29:50:817Jacopo Vivian: it does not account for the biggest amount of a of the heat loss.
29:59:880Jacopo Vivian: So it having 50% in summer is not like having 50% in winter, because in winter you distribute 10 times more heat than in summer, even more
30:13:690Jacopo Vivian: so in percentage terms, the heat loss is very high in summer in absolute terms.
30:27:240Jacopo Vivian: they are summer and winter are are similar. Okay? Because you have the same fluid circulating through the network, and the network has the same length.
30:39:530Jacopo Vivian: The only variable here is right. You have the possibility to change the flow and to change the temperature.
30:48:380Jacopo Vivian: So you can slightly reduce in absolute terms from winter to summer, because you have lower flow and lower
30:59:740Jacopo Vivian: supply temperature.
31:03:780Jacopo Vivian: So overall, why, from the user's perspective. Why should I? Private user connect to a distributing network?
31:14:440Jacopo Vivian: There should be an economical advantage.
31:17:510Jacopo Vivian: Okay, so if you have local generation.
31:24:100Jacopo Vivian: say, for example, an autonomous gas boiler or a centralized gas boiler. If you.
31:30:430Jacopo Vivian: if you live in a condominium, the the euros that you spend should be
31:43:820Jacopo Vivian: there should be, at least they should. In the with the district heating, you should not exceed this value. Okay, so there is a competing technology which is the autonomous boiler.
31:59:710Jacopo Vivian: and from a district heating operator it means that you need to have
32:08:685Jacopo Vivian: operating costs that are sensibly lower than those for the users.
32:15:120Jacopo Vivian: because you need also to pay back for the initial investment.
32:20:30Jacopo Vivian: Okay?
32:21:130Jacopo Vivian: So the cost for the operator is not only related to the energy expanding
32:31:20Jacopo Vivian: to the energy cost to the operating cost.
32:35:200Jacopo Vivian: Okay, they are also related to the investment cost that needs to be
32:40:650Jacopo Vivian: to be paid back. Of of course, after I don't know 15 years of operation. You may be already paid back the
32:49:930Jacopo Vivian: the infrastructure, and you have only a negligible part here.
32:56:310Jacopo Vivian: Okay, but the just. Remember this for
33:02:250Jacopo Vivian: that, for for the users and for the operator. This is not the same. Okay.
33:11:580Jacopo Vivian: Talking about the investment cost course, the investment in terms of euros per meter
33:20:650Jacopo Vivian: is not the same depends on the diameter. So the bigger the pipe, the bigger the cost. Okay.
33:27:930Jacopo Vivian: But remember that it also depends on where you install that pipe, because installing that pipe in.
33:41:210Jacopo Vivian: I don't know.
33:43:610Jacopo Vivian: Volta Bar also is not the same of installing that pipe in Via Venet. Yeah.
33:50:740Jacopo Vivian: Guy, talking about Padwa, because you need to interrupt many services, as you can see
34:00:120Jacopo Vivian: by looking at the tramway lines. Okay, it is not easy to make a public infrastructure
34:10:260Jacopo Vivian: because you need services to stop.
34:13:719Jacopo Vivian: You need to change the traffic in the city.
34:17:780Jacopo Vivian: There will always be people complaining about about it. There will be a lot of people trying to stop the infrastructure.
34:28:409Jacopo Vivian: And so there must be a lot of political
34:33:475Jacopo Vivian: will in order to build this infrastructure. This is why it is not very common in Italy.
34:44:90Jacopo Vivian: So, having a pipe in a park passing through a park, provided that the park is public
34:53:30Jacopo Vivian: could be better than having the same pipe passing through
34:57:930Jacopo Vivian: street that is very crowded with a lot of people, a lot of cars passing through it. Okay?
35:05:790Jacopo Vivian: So it is not only about the the pipe diameter is also where you install the pipe that will determine the investment.
35:17:340Jacopo Vivian: So in order to size the district heating network. You already know how to size the hydronic system. So it's basically the same
35:31:590Jacopo Vivian: or at least it is very similar.
35:35:890Jacopo Vivian: Here there are some difference.
35:39:230Jacopo Vivian: some differences. 1st of all. You don't exactly know what is the hit demand, because you estimated.
35:49:100Jacopo Vivian: but you don't know exactly what will be exactly the heat demand in the future.
35:56:270Jacopo Vivian: because you're not installing a hydronic system for a building
36:01:310Jacopo Vivian: where the heat, the demand, is given by the building itself and by its terminal units.
36:07:100Jacopo Vivian: Okay, in this case the heater demand depends on the
36:12:530Jacopo Vivian: customers that in the future will connect or will not connect to the to the network. So there is uncertainty.
36:20:70Jacopo Vivian: and there are heat losses.
36:23:100Jacopo Vivian: Okay?
36:25:205Jacopo Vivian: So it losses that maybe on a building level they are negligible.
36:31:830Jacopo Vivian: Okay? Or at least the
36:34:500Jacopo Vivian: you don't distribute the heat for kilometers in a single building. Typically so in case of district heating networks, heat losses are also important.
36:48:350Jacopo Vivian: Once you determine the the power that you need to deliver.
36:54:730Jacopo Vivian: you have a you use a nominal delta T, and you find a corresponding mass flow rate.
37:01:850Jacopo Vivian: Then, as we did for the hydronic system, you can set the velocity or a constant pressure loss. Okay.
37:13:750Jacopo Vivian: remember, for hydronic system. I gave you a ranger between 150 and
37:23:950Jacopo Vivian: 400, if I remember correctly, and I told you
37:28:500Jacopo Vivian: 250 Pascal per meter is a good target.
37:35:100Jacopo Vivian: The same here. Okay, so it's more or less. We are in the same, the same range.
37:44:760Jacopo Vivian: Okay? So maybe not 150, but 200 Pascal per meter is a reasonable value.
37:59:300Jacopo Vivian: Again.
38:03:740Jacopo Vivian: we have. I don't know if
38:12:150Jacopo Vivian: the distribution network.
38:19:210Jacopo Vivian: There is a problem with the microphones. I guess.
39:10:880Jacopo Vivian: Okay.
39:24:380Jacopo Vivian: so concerning the distribution network, we can have a steel pipes.
39:35:330Jacopo Vivian: of course, they are more used for transmission lines because they are big pipes. They can be joined by welding.
39:48:30Jacopo Vivian: They are widely available.
39:50:520Jacopo Vivian: And yeah, of course they have higher strength than plastic pipes.
40:01:319Jacopo Vivian: They are costly. Of course, one of their main problems is corrosion, so they require corrosion protection
40:12:760Jacopo Vivian: and they require skilled labor force for for welding.
40:18:500Jacopo Vivian: Okay, the installation is lower than plastic pipes, especially for larger diameters.
40:27:400Jacopo Vivian: Concerning plastic pipes.
40:31:130Jacopo Vivian: We have a low weight pipes. They can be fusion welded. Okay?
40:39:260Jacopo Vivian: And the
40:44:790Jacopo Vivian: They can also come. They can also be pre-insulated. So they they have some advantages over
40:58:710Jacopo Vivian: over steel pipes.
41:03:570Jacopo Vivian: This is how our pipes should look like, okay.
41:11:923Jacopo Vivian: The 1st example. On the left are brains related between pipes buried in the ground.
41:21:580Jacopo Vivian: Why do I call them twin pipes? Because, actually, if you look from the outside that they are a single pipe. But inside the single pipe there are 2 pipes with the insulation in between.
41:36:410Jacopo Vivian: Okay, so there is a casing insulation. At the point.
41:42:990Jacopo Vivian: There is a casing, the insulation and the case up of the of the pipe itself.
42:01:590Jacopo Vivian: Okay, in this case it is written airspace, but the geometry is the same of the. So this is a this is actually an example of 2 pipes
42:16:990Jacopo Vivian: in a in a A in a cavity which is a which is a cylindrical. Okay?
42:29:430Jacopo Vivian: But the basically twin pipes are also available.
42:34:940Jacopo Vivian: Okay, I don't know if I have other picture of twin pipes, but
42:38:990Jacopo Vivian: they have the same section. It's
42:43:760Jacopo Vivian: this is like the one that we will see in not the alabago in next Tuesday, so we have a hole in the ground
42:54:980Jacopo Vivian: where the pipes are laid, and we will. We could also. I don't know if we will do it
43:03:330Jacopo Vivian: you can also walk here in the barrel for the in Italian. Okay.
43:12:865Jacopo Vivian: this is useful also in in Lenaro, in Agripolis. They have this.
43:18:830Jacopo Vivian: so they have big corridors underground where you can walk.
43:24:280Jacopo Vivian: and this is good for inspection.
43:27:760Jacopo Vivian: But it is not the usual
43:32:520Jacopo Vivian: on a city for for this ticketing systems at city scale. So it is more usual in these situations where you have a limited number of buildings
43:45:490Jacopo Vivian: like in the University, and in the case of university buildings, for example.
43:56:850Jacopo Vivian: And here this is another typical situation where you have the pipes buried in the ground. In this case
44:07:930Jacopo Vivian: you have a ditch.
44:12:30Jacopo Vivian: Okay? So you need to dig.
44:15:380Jacopo Vivian: and the width of the ditch
44:18:990Jacopo Vivian: should be high enough to prevent compression of the of the pipe in case you are on a
44:30:46Jacopo Vivian: on a street where deer and other vehicles, and that can drive.
44:40:770Jacopo Vivian: Okay?
44:42:50Jacopo Vivian: So you have a minimum width, which depends also on the material that is used in the ditch as a filling material.
44:55:750Jacopo Vivian: Here you can see it is beaten sand. So this highly compressed and
45:06:290Jacopo Vivian: okay, and the slope of the ditch. So this angle here
45:13:230Jacopo Vivian: is made to prevent the landslide.
45:16:820Jacopo Vivian: Okay, that could shift the position of the pipes.
45:31:760Jacopo Vivian: Really don't know how to stop this, because
45:38:460Jacopo Vivian: I'm an impulsive spinner. Look!
45:41:280Jacopo Vivian: Oh.
45:50:330Jacopo Vivian: Manu Cambianula.
45:55:180Jacopo Vivian: we need to suck on my father.
46:03:960Jacopo Vivian: Okay, this is the network that we will.
46:10:180Jacopo Vivian: Yes, this is the network that we will visit on Tuesday.
46:14:740Jacopo Vivian: This is, of course, an old an old plan.
46:20:70Jacopo Vivian: This is the valitionary building, right.
46:25:70Jacopo Vivian: This is the heat supply station.
46:30:510Jacopo Vivian: This is the mechanical engineering complex.
46:35:60Jacopo Vivian: And you can see they thought at the time we could extend to the psychology buildings. In fact, nowadays they are also connected to the network
46:47:170Jacopo Vivian: and the mainsa, I don't think, is connected anymore.
46:51:600Jacopo Vivian: So there is a ditch, but it I don't think it is used.
46:56:210Jacopo Vivian: I think we will visit the. And here you have the the mechanical laboratories. Okay, so
47:10:370Jacopo Vivian: we will visit the heating station, which is here, and the cooling station that is here that has been completely refurbished. They finished the works last week, and they should start the cooling.
47:28:490Jacopo Vivian: the the new cooling station should start the operation.
47:35:160Jacopo Vivian: I think soon.
47:37:690Jacopo Vivian: I don't know when, but
47:41:480Jacopo Vivian: it is a quite a matter of days, and
47:48:970Jacopo Vivian: yes, and we will also visit the substations where you will also, see some
47:58:590Jacopo Vivian: some not only the substation, but also some air handling units of the
48:04:340Jacopo Vivian: that supply the the building of mechanical engineering.
48:11:100Jacopo Vivian: So this is an older network. It was built many years ago.
48:18:920Jacopo Vivian: and it is still a constant flow network.
48:23:130Jacopo Vivian: So we have three-way valves. Here. You find them
48:32:670Jacopo Vivian: beautiful.
48:34:120Jacopo Vivian: Okay, you can see they are on the return. On the return. You have a 3 way mix involved
48:44:780Jacopo Vivian: that by opening it will make some of the flow bypass the heat exchanger.
48:53:890Jacopo Vivian: So in this case the nominal master rate is distributed to the buildings, and it only we only regulate the
49:05:927Jacopo Vivian: the we have a variable flow to the heat exchangers in the substation.
49:13:740Jacopo Vivian: which is, of course, very bad from an efficiency point of view.
49:20:550Jacopo Vivian: This is the heat supply station.
49:23:640Jacopo Vivian: which is also very inefficient and not inefficient, but
49:30:100Jacopo Vivian: not very environmentally friendly because we only have 3 gas boilers. They have been replaced over the years.
49:39:990Jacopo Vivian: so nowadays they are quite smaller than the ones we had before.
49:48:90Jacopo Vivian: You can see here we have the primary pumps.
49:52:330Jacopo Vivian: the manifold and the lines going to the network.
49:56:810Jacopo Vivian: and then we have the return, the return manifold, and going back to the
50:04:770Jacopo Vivian: to the, to the boilers.
50:07:180Jacopo Vivian: Okay.
50:14:730Jacopo Vivian: this is a a normal sketch of the cooling station.
50:21:10Jacopo Vivian: I could ask the new one, because I guess there should be a projector.
50:28:260Jacopo Vivian: So here we have the chillers.
50:31:860Jacopo Vivian: as you can see, we have individual pumps
50:35:900Jacopo Vivian: for the chillers. Remember that here we need to have constant flow.
50:42:900Jacopo Vivian: So we have a decoupled distribution because we have this bypass flow here.
50:48:710Jacopo Vivian: and we have the option to
50:52:83Jacopo Vivian: pump to use secondary pumps
50:56:360Jacopo Vivian: on the on the lines connected into the building. And, by the way, you can see that in some cases we don't have a heat exchanger.
51:08:410Jacopo Vivian: which means that the water, the chilled water in the cooling network reaches the phone calls.
51:18:310Jacopo Vivian: It is the same water, whereas for
51:24:80Jacopo Vivian: buildings that are far away, like psychology building psychology buildings and
51:30:346Jacopo Vivian: language and Congress center of psychology, we have a heat exchanger. We have placed heat exchanger
51:39:905Jacopo Vivian: so that we don't need to have a separate pump, and we use a two-way valve to regulate the flow.
51:48:10Jacopo Vivian: using the same header given by the primary pumps in the cooling station.
51:55:190Jacopo Vivian: So we have a mixed situation depending on the building.
52:01:130Jacopo Vivian: Okay, so overall, we can distinguish networks
52:10:810Jacopo Vivian: based on direct versus indirect connection.
52:16:90Jacopo Vivian: In most cases we have indirect connection, meaning that we have a heat exchanger in the substation.
52:26:340Jacopo Vivian: so that the heat carrier fluid of the network is
52:31:950Jacopo Vivian: separate from the heat carrier fluid of the building.
52:36:370Jacopo Vivian: This was an exception.
52:38:780Jacopo Vivian: This is a an example of direct connection.
52:42:980Jacopo Vivian: Where you have some buildings that receive the chilled water directly from the cooling network.
52:51:140Jacopo Vivian: Okay, but in general, these ticketing systems have indirect connection. So there is a heat exchanger in the substation.
53:04:10Jacopo Vivian: And then the substations can be
53:07:980Jacopo Vivian: can be distinguished based on the whether they are serving space, heating only domestic hot water only, or both.
53:20:870Jacopo Vivian: Right?
53:25:390Jacopo Vivian: And also we have 2 options, we have a constant flow versus variable flow.
53:32:800Jacopo Vivian: So constant flow means that we have the situation.
53:41:270Jacopo Vivian: This situation here 3 way bond on in the substation.
53:48:680Jacopo Vivian: Okay? So you always distributed the.
53:52:850Jacopo Vivian: And now we now accelerated, and the
54:00:90Jacopo Vivian: variable flow means that we have this situation here
54:06:510Jacopo Vivian: right 2 way valid in the substation.
54:10:980Jacopo Vivian: So when the 2 ways are closes, the flow rate is reduced.
54:16:640Jacopo Vivian: and therefore we have a variable flow system, and then we can have.
54:24:550Jacopo Vivian: we can have a variable speed bump in the
54:28:500Jacopo Vivian: in the supply station to reduce the
54:33:930Jacopo Vivian: energy, the electrical energy consumed by the pump.
54:40:20Jacopo Vivian: Okay.
54:41:340Jacopo Vivian: but in general, you can also have a constant speed bump within a variable speed in a variable flow system.
54:49:730Jacopo Vivian: Just spend more for making the water circulate system.
54:56:90Jacopo Vivian: We have seen in previous lectures.
55:03:290Jacopo Vivian: And
55:29:290Jacopo Vivian: okay, so it doesn't matter.
55:34:830Jacopo Vivian: This is a typical substation of a distributing system with the variable flow.
55:42:50Jacopo Vivian: because you have that the motorized 2 way valve on the supply.
55:48:480Jacopo Vivian: Okay, and this is controlled by a controller here.
55:54:580Jacopo Vivian: So the actuator of the valve is controlled by a controller.
55:59:430Jacopo Vivian: That depends.
56:02:370Jacopo Vivian: That wants to reach a certain supply temperature on the secondary side.
56:09:270Jacopo Vivian: So how can it work?
56:14:980Jacopo Vivian: What these said?
56:17:260Jacopo Vivian: This is the going normally to the
56:21:420Jacopo Vivian: radiators of the building. Okay, and then back.
56:27:700Jacopo Vivian: But imagine that we close the thermostat during the night
56:37:560Jacopo Vivian: because we don't want to heat up the building too much
56:42:743Jacopo Vivian: we want to save energy. So we have a nice sight, Berkeley.
56:49:60Jacopo Vivian: Okay, in this case there will be a signal coming from the thermostat, and saying to the
57:02:220Jacopo Vivian: and saying to the flow that it will that it can stop right?
57:10:260Jacopo Vivian: So we stopped that the the flow in the secondary side does not circulate. For example, during the night.
57:19:680Jacopo Vivian: in the morning, when the people wake up.
57:23:530Jacopo Vivian: they want to have a warmer building
57:26:200Jacopo Vivian: they have. They want to have a comfortable environment.
57:33:590Jacopo Vivian: So they switch on the thermostat again.
57:37:630Jacopo Vivian: So what happens is that
57:40:720Jacopo Vivian: the thermostat will send the signal to the controller. That will say, Okay, now, you need to
57:48:230Jacopo Vivian: circulate the flow. So you need to switch on the pump on the secondary side, right?
57:55:880Jacopo Vivian: And also you need to
58:04:90Jacopo Vivian: and also you need to set a certain supply temperature.
58:10:370Jacopo Vivian: The supply temperature can be set with the weather compensation curve depending on the outdoor air temperature. Okay, for example, for an old building red line
58:22:950Jacopo Vivian: we could have if outside, we have 0 degrees this temperature here.
58:28:630Jacopo Vivian: So the controller receives this.
58:32:50Jacopo Vivian: So you cannot, for example, 60 degrees whatever, but they will turn when it starts circulating.
58:44:330Jacopo Vivian: It has a a lower temperature here. Okay?
58:50:420Jacopo Vivian: So basically, there is the difference between the set pointer
58:54:980Jacopo Vivian: and the temperature that is circulating in the pipe.
59:01:40Jacopo Vivian: So you have a a controller that will adjust what we'll adjust the
59:13:980Jacopo Vivian: the position of this 2 way bundle in order for the supply temperature
59:23:250Jacopo Vivian: to reach the desired value, and to
59:27:320Jacopo Vivian: therefore nullify this error between measured temperature measure supply temperature and set point.
59:36:250Jacopo Vivian: Okay, so basically, the and the 2 way valve is closed when there is no heat demand, when the
59:52:300Jacopo Vivian: when there is no requirements from the users.
59:59:640Jacopo Vivian: and when it opens, the position is driven by a controller like this one.
00:06:470Jacopo Vivian: Okay, where the error can be measured, for example, between the
00:12:190Jacopo Vivian: supply temperature and the set point temperature that we set
00:18:540Jacopo Vivian: from a system operation point of view, what happens when the 2 way valves close because we have
00:28:900Jacopo Vivian: dozens or hundreds of buildings connected.
00:34:980Jacopo Vivian: If they all change the position of the 2 way. Rather.
00:40:70Jacopo Vivian: we have a completely different characteristic curve of the network, the distributing network.
00:50:10Jacopo Vivian: So basically, if imagine we have a.
00:59:720Jacopo Vivian: we have 2 lines, right?
01:04:510Jacopo Vivian: This is just an example. We have 2 lines, one is a
01:10:440Jacopo Vivian: 200 around 200 meter, and then now we have another line, which is
01:20:700Jacopo Vivian: so one is more or less 300 meter and the other 400 meter. So this is with a certain flow rate.
01:28:680Jacopo Vivian: right?
01:30:210Jacopo Vivian: And this is what happens if suddenly the valves open, and because the buildings want more.
01:41:800Jacopo Vivian: Keep the from the network.
01:46:270Jacopo Vivian: There is a higher flow rate circulating in the network.
01:50:390Jacopo Vivian: and therefore there is a higher pressure loss in those lines
01:56:500Jacopo Vivian: you can see that the slope.
02:02:640Jacopo Vivian: the slope of these lines increases
02:06:900Jacopo Vivian: because the continuous pressure losses increase
02:11:50Jacopo Vivian: due to the higher flow rate circulating in the network. Remember that the Delta P
02:17:820Jacopo Vivian: is proportional to the square of the flow.
02:23:300Jacopo Vivian: And what is important from an operator point of view
02:28:920Jacopo Vivian: is important, that the difference that we have at the end of the network. So
02:37:330Jacopo Vivian: if you remember, when we talked about hydronic system, I was talking about the hydraulically farthest terminal unit
02:49:530Jacopo Vivian: got it that we should always, always make sure that all the terminal units receive flow
02:59:490Jacopo Vivian: in the district heating network. It is exactly the same.
03:03:960Jacopo Vivian: But instead of terminal units, we have buildings.
03:07:570Jacopo Vivian: Okay, so we have substations.
03:10:160Jacopo Vivian: We need to make sure or better, the system operator needs to make sure
03:15:920Jacopo Vivian: that all the substations receive flow.
03:20:830Jacopo Vivian: What is the condition for the flow? Circulate in all the heat exchangers
03:26:180Jacopo Vivian: that there is a Delta P between the supply and the return.
03:31:160Jacopo Vivian: So there is a minimum delta. P, between this point here and this point here.
03:39:640Jacopo Vivian: Okay, so that this is the condition.
03:49:520Jacopo Vivian: Here, you can see another example.
03:54:640Jacopo Vivian: right? The the concept is the same.
03:57:450Jacopo Vivian: Instead of having 2 lines. This is representing the single line. Okay.
04:06:630Jacopo Vivian: course, networks are complex. But the concept is the same
04:13:260Jacopo Vivian: in the sub. In the main supply station. We have Delta P,
04:19:70Jacopo Vivian: due to the main bump here.
04:22:110Jacopo Vivian: Okay? And then we have continuous pressure losses.
04:26:210Jacopo Vivian: We need to make sure that in the critical customer, okay.
04:33:930Jacopo Vivian: they that the P is at least the
04:40:600Jacopo Vivian: at least 150 Kilo Pascal, or 100 Kilo Pascal, so more or less one.
04:52:620Jacopo Vivian: Yes, so
04:58:780Jacopo Vivian: On the other hand, we don't.
05:02:60Jacopo Vivian: We don't want to waste energy.
05:05:730Jacopo Vivian: So we want to reduce the flow and the the Delta P of the main bumper.
05:19:770Jacopo Vivian: This setup page.
05:21:750Jacopo Vivian: It's something that we can that we can regulate the
05:28:430Jacopo Vivian: by changing the speed of the pump.
05:32:60Jacopo Vivian: Okay, so the the Delta P and the flow rate, we change it together.
05:38:600Jacopo Vivian: and there is a trade off between
05:41:370Jacopo Vivian: being sure that the most critical user is always satisfied and and the saving the energy.
05:55:970Jacopo Vivian: Okay? Because if the Delta P is low to save energy. We might have that
06:02:150Jacopo Vivian: and problems at the critical users.
06:07:180Jacopo Vivian: This is an example of network. This is the networking Verona Central, Chitta.
06:15:260Jacopo Vivian: And you can see here, where is the critical line?
06:21:260Jacopo Vivian: The main supply station is here, this one here, and then we have another supply station here.
06:34:590Jacopo Vivian: which is, recovering heat from an industrial process. And here we have a backup
06:42:960Jacopo Vivian: station with the backup gas borders.
06:48:260Jacopo Vivian: So basically, most of the time, all the heat is provided by this station.
06:54:60Jacopo Vivian: In this station we have gas fire, internal combustion engines, heat pumps, and gas carriers.
07:03:730Jacopo Vivian: so you can see that we don't have a line. So it is not very easy to understand that where is the critical task? Here
07:14:450Jacopo Vivian: we simulated the network, and we found that
07:18:870Jacopo Vivian: I don't have the pictures here, but we found that
07:22:710Jacopo Vivian: critical. So the lowest Delta P, between supply and return was more or less. Here
07:30:330Jacopo Vivian: you can see that the we have a lot of buildings connected to the network.
07:36:290Jacopo Vivian: Here we have Arena Liverona, by the way, and that here
07:41:450Jacopo Vivian: I don't know if you can see it. But here there is the other river.
07:48:808Jacopo Vivian: In this case we have 25 kilometers of pipes, almost 250 customers.
08:02:810Jacopo Vivian: We have a an annual energy demand of 70,000 megawatt hours per year.
08:11:900Jacopo Vivian: and a thermal peak load of almost 40 megawatt.
08:18:990Jacopo Vivian: How does the operator regulate this?
08:22:270Jacopo Vivian: Yes, I have it.
08:25:50Jacopo Vivian: The do you remember that I said that we can set a rule for the Delta P as a function of the flow
08:33:640Jacopo Vivian: if we have a variable speed problem.
08:36:399Jacopo Vivian: So we change the speed in order to have a certain
08:42:340Jacopo Vivian: control of the flow in this in the main supply station.
08:46:979Jacopo Vivian: And this is the what they have in Verona Center, China.
08:52:140Jacopo Vivian: So they set this curve, which is the best trade, offer
08:57:620Jacopo Vivian: to save energy of the main pump.
09:01:300Jacopo Vivian: but to avoid having low Delta P
09:07:180Jacopo Vivian: to the users in in this position, because they are hydraulically disadvantaged.
09:17:460Jacopo Vivian: Right?
09:20:439Jacopo Vivian: So what happens if the operator decides to
09:24:670Jacopo Vivian: reduce this curve to lower Delta P.
09:29:490Jacopo Vivian: They will receive some calls from the people that will complain
09:35:420Jacopo Vivian: because they don't have enough key.
09:38:899Jacopo Vivian: Okay? So this is from a
09:43:20Jacopo Vivian: hydraulic point of view from the
09:46:850Jacopo Vivian: Powerpoint. Yes, and this is how
09:50:880Jacopo Vivian: it looks like. So that same points
09:54:20Jacopo Vivian: of flow rate that you see on the X axis. Here
09:57:600Jacopo Vivian: you find as a function of time here.
10:00:740Jacopo Vivian: So this is a typical
10:04:450Jacopo Vivian: load curve of this is the district heating network of of Verona in a typical week.
10:12:750Jacopo Vivian: Okay?
10:13:690Jacopo Vivian: And as you can see it, since this is a variable flow network, not like the north one.
10:23:780Jacopo Vivian: the flow is following the load.
10:31:510Jacopo Vivian: Right.
10:34:390Jacopo Vivian: What do you expect? In a constant flow in a constant flow? We will have a constant flow, which is something like this.
10:44:250Jacopo Vivian: a constant blue line here instead of having it.
10:49:390Jacopo Vivian: These variations of the flow.
10:56:440Jacopo Vivian: I told you that one of the advantages of having district heating networks is to have a
11:02:870Jacopo Vivian: renewable energy sources.
11:06:350Jacopo Vivian: So
11:10:310Jacopo Vivian: The point is that the you cannot just put the any hit source in any position.
11:22:120Jacopo Vivian: Why? Because if you place a and a new heat source here.
11:34:510Jacopo Vivian: They need to win this Delta P to inject it into the network.
11:40:60Jacopo Vivian: Well, if you place it, the far away.
11:44:120Jacopo Vivian: Okay, far away from the station. Then there's the fee that needs to be that needs to be.
12:00:420Jacopo Vivian: I'd say that the punch must give to the flow is lower.
12:06:770Jacopo Vivian: So in case we have a and why? Why? In distributing networks, it is not likely
12:19:600Jacopo Vivian: power distribution metrics where we can just place a Pv system on the roof
12:25:420Jacopo Vivian: and supply electricity to the network.
12:29:340Jacopo Vivian: because, from a hydraulic point of view.
12:32:500Jacopo Vivian: it is not easy to regulate the the flow even by
12:40:128Jacopo Vivian: by renewable energy sources, and they cannot
12:43:860Jacopo Vivian: always be placed in any position due to this pressure differential. Here you see what happens to the pressure differential. If you place.
12:55:630Jacopo Vivian: for example, a solar heating plant in this position. So this is the main supply station. These are customers. Okay, at the end of these branches.
13:06:810Jacopo Vivian: And suddenly, at at a certain point, we want to place a solar heat production plant. Here
13:13:890Jacopo Vivian: you can see that the pressure differential meaning that the pressure difference between supply and return will change, so that the critical customer is no more here. But it is here.
13:29:730Jacopo Vivian: Okay. So from a operator point of view, having other operators
13:38:420Jacopo Vivian: is not very easy to manage.
13:41:340Jacopo Vivian: Okay, so it is, of course, possible, but it is not usual.
13:48:660Jacopo Vivian: So it is done only with the big customers that have the technical capabilities to regulate the
14:05:88Jacopo Vivian: heat fluid according to the needs of the system operator.
14:11:370Jacopo Vivian: This is the distribution of
14:15:583Jacopo Vivian: distributing systems in European countries.
14:20:940Jacopo Vivian: You can see they are mostly concentrated in the North and in the East, because, as I told you.
14:27:710Jacopo Vivian: they were very much diffused in the Soviet Union.
14:35:710Jacopo Vivian: Okay, that's why you have a lot of systems. Also, for example, in Poland and in other Eastern countries.
14:51:560Jacopo Vivian: this is we don't care. This is the distribution of district heating systems in Italy.
15:01:190Jacopo Vivian: where only a small amount of the hit demand is supplied by these different systems.
15:08:170Jacopo Vivian: Maybe it's a bit higher, but
15:11:40Jacopo Vivian: the order of an Army 2 is correct.
15:15:540Jacopo Vivian: and you can see the original distribution.
15:20:00Jacopo Vivian: Of course they are more diffused in the North, because in the north we have a higher heat density.
15:29:350Jacopo Vivian: The linear heat density I was talking about before
15:33:620Jacopo Vivian: is also depending on the weather.
15:36:700Jacopo Vivian: This is why, in Northern Europe it is a
15:41:210Jacopo Vivian: quite common. It is one of the reasons why it is more common to have history heating in Northern Europe, due to colder climates compared to Southern Europe.
15:51:760Jacopo Vivian: since in Italy we have different latitudes, different weather conditions at different latitudes.
16:00:133Jacopo Vivian: We have a concentration of the systems, mostly north of Italy and in northern regions.
16:10:601Jacopo Vivian: You see, Lombardy and the amount are the main at Thursa.
16:18:310Jacopo Vivian: And then, though although the heated demand is significant, it does not.
16:24:510Jacopo Vivian: He's not very.
16:26:830Jacopo Vivian: It's not very diffused in in vanity, right?
16:37:750Jacopo Vivian: So apart from say.
16:44:570Jacopo Vivian: controlling the heat supply to to locally. Okay, so more like energy security, energy security
16:57:390Jacopo Vivian: advantage. We have the option. The the main advantage is the
17:04:30Jacopo Vivian: possibility to decarbonize the heating sector by using this tech heating, how can we do it?
17:11:880Jacopo Vivian: The 1st step is to reduce the operating temperatures, because this has 2 advantages.
17:21:60Jacopo Vivian: 1st of all, we reduce the heat losses the ground course.
17:27:340Jacopo Vivian: and secondly, it is easier to integrate the renewable energy sources, because.
17:34:860Jacopo Vivian: if or other other sources in general, because they lower the supply temperature.
17:42:960Jacopo Vivian: the lower the temperature difference between any source and the network.
17:48:310Jacopo Vivian: Okay, so if we have a source at 50 degrees.
17:53:770Jacopo Vivian: and the network is at 90. We have a delta T of 40,
17:59:290Jacopo Vivian: but if the network is a 70, then Delta T is 20 is half.
18:04:590Jacopo Vivian: So that means if we use a heat pump, we need to.
18:09:550Jacopo Vivian: We have half of the Delta T between the source and the C
18:14:10Jacopo Vivian: where the sync is the network. Okay, so
18:20:100Jacopo Vivian: what are the sources that we can use?
18:25:120Jacopo Vivian: Solar thermal is an option, although this is not diffused in Italy
18:32:87Jacopo Vivian: ground and air source, heat pumps, and industrial waste.
18:41:930Jacopo Vivian: And then we have other options like introducing thermal storage systems.
18:50:310Jacopo Vivian: both not only seasonal, but also daily thermal storage.
18:55:950Jacopo Vivian: They are important, because, especially if we have a
19:00:370Jacopo Vivian: heat pumps and the core generation systems that exchange
19:06:610Jacopo Vivian: that produce and consume electrical energy, it is more convenient to produce electrical energy when the price is high and consume electrical energy when the price is low.
19:22:390Jacopo Vivian: So in this case it is very convenient to have a thermal storage system.
19:27:990Jacopo Vivian: Seasonal thermal storage are used in again in northern countries where the district heating networks are, and quite the
19:39:410Jacopo Vivian: mature technology where they store heat during sun for use during winter.
19:48:610Jacopo Vivian: Good
19:53:82Jacopo Vivian: this is, okay. Already. Nowadays, we have
20:00:670Jacopo Vivian: minus 25% of the energy consumption.
20:06:232Jacopo Vivian: With the Italian district eating mixer compared to they replaced individual systems so
20:17:870Jacopo Vivian: due mainly due to the presence of cogeneration unit.
20:23:180Jacopo Vivian: A cogeneration can be either gas fired or biomass fired.
20:29:600Jacopo Vivian: Then we have direct renewables like geothermal
20:35:205Jacopo Vivian: waste heat from industrial processes, heat pumps, and the
20:43:230Jacopo Vivian: yes, so biomass for generation is this one.
20:47:100Jacopo Vivian: He's very frequented in the mounting regions.
20:54:220Jacopo Vivian: Okay, and minus 30% of Co 2 emissions compared to individual system.
21:02:190Jacopo Vivian: meaning, if you are a building with your additional.
21:08:930Jacopo Vivian: even condensing a spoiler. And you take electricity from the network for the other uses.
21:17:490Jacopo Vivian: If, instead, you take the heat from the district heating network, you are already saving 30% reducing
21:27:660Jacopo Vivian: Co 2 emissions. On average, of course, 5, 30%
21:35:90Jacopo Vivian: the better the network meaning, the the more is the renewable.
21:43:640Jacopo Vivian: the renewable share in the energy supply. Mix of the network the better the figure of the Co. 2 and primary energy consumption reduction.
21:54:320Jacopo Vivian: Remember that in the future buildings will need to be
22:00:46Jacopo Vivian: we will need to refurbish
22:03:50Jacopo Vivian: all those old buildings with very low energy performance. So energy, class energy performance class F or G
22:15:630Jacopo Vivian: need to be renovated in the future. So one option. But you cannot always renovate buildings.
22:25:510Jacopo Vivian: For example, we have a
22:28:770Jacopo Vivian: buildings in the city center of Padova. Imagine a building close to Palazzo Mall or to
22:36:140Jacopo Vivian: I don't know if yesterday has it.
22:38:810Jacopo Vivian: How can we? I don't know about those meetings. Can we just do the thermal installation of the envelope?
22:45:710Jacopo Vivian: I don't think so.
22:47:310Jacopo Vivian: So one option is to use
22:50:720Jacopo Vivian: district heating network to reach buildings in that we cannot otherwise renovate. Okay, working on the envelope.
23:00:990Jacopo Vivian: And this is, in fact, the one option that
23:04:210Jacopo Vivian: finally the municipality of Padova is considering so
23:12:20Jacopo Vivian: as to 5 as a I still have 5 min. So I want to talk about the
23:19:620Jacopo Vivian: another distributing network.
23:22:925Jacopo Vivian: That is, we change that. Here we have. This is not very big is around 20 kilometers.
23:29:580Jacopo Vivian: and the maybe 40 gigawatt hours, 40,000 megawatt hours per year of thermal energy distributed.
23:41:737Jacopo Vivian: The current situation is that there are the older code generation units. So gas fired the
23:51:710Jacopo Vivian: internal combustion energies the gas boilers.
23:57:540Jacopo Vivian: and there was a a well where
24:04:10Jacopo Vivian: and he in the seventies looked for gossip or oil.
24:11:350Jacopo Vivian: They didn't find oil, but they find that they found the groundwater at the interesting temperatures.
24:20:190Jacopo Vivian: So the operator thought, okay, I
24:23:970Jacopo Vivian: I can extract this groundwater to supply heat to my network.
24:29:970Jacopo Vivian: And this is, in fact, what happens?
24:34:270Jacopo Vivian: This is the this is the well with the pipe going good down. I don't know.
24:47:100Jacopo Vivian: I don't know how many meters in the ground I don't remember, but I would say maybe
24:56:180Jacopo Vivian: 2 2 kilometers below surface, or something like that. So deep geothermal. Okay, and the the situation
25:09:140Jacopo Vivian: is that this groundwater is extracted.
25:14:240Jacopo Vivian: and then it is released in a kernel right
25:19:940Jacopo Vivian: and the heat exchanger. There is a heat exchanger that provides heater to the, to the network.
25:29:530Jacopo Vivian: With the current configuration. The flow rate is 100 cubic meters of groundwater per hour got it.
25:38:740Jacopo Vivian: and the the operator has a plan to refurbish the whole heat supply station, and to make this
25:50:300Jacopo Vivian: smarter mover.
25:52:850Jacopo Vivian: They ask the authorization to extract more groundwater. So they extract
26:01:410Jacopo Vivian: 150 cubic meter per hour, so plus 50%.
26:08:260Jacopo Vivian: And then they pull it down the water until then
26:14:880Jacopo Vivian: 62 degrees, and with this 1st temperature they preheat the temperature coming from their return.
26:25:930Jacopo Vivian: So the return line of the network is preheated, and then goes in 3 3 heat pumps that
26:39:910Jacopo Vivian: provide 3 temperature
26:44:50Jacopo Vivian: steps, one between 62, and 68, 1, 68, the 73, and then 73, 80, which is the supply temperature of the network.
26:58:740Jacopo Vivian: What source use this heat pump? So on this, on the condenser side, we have the water coming from the network. Okay? So the network.
27:12:220Jacopo Vivian: the the water of the of the network itself.
27:16:380Jacopo Vivian: On the supply side, we have a loop, which is heated by the groundwater at the lower temperature, so
27:26:350Jacopo Vivian: between 62, so they they can cool down the water. The groundwater from 60 to to 15 degrees
27:39:450Jacopo Vivian: with the evaporators of the it pops in this way
27:47:860Jacopo Vivian: instead of with this configuration, instead of recovering one megawatt, they recover, I think
28:02:530Jacopo Vivian: something like 10 megawatt, or
28:06:630Jacopo Vivian: I don't remember exactly the size, but the quite a big difference, because they use all the delta D between the extracted groundwater
28:18:50Jacopo Vivian: and then discharge.
28:20:870Jacopo Vivian: Yeah, Richard, so this is how it will work.
28:28:930Jacopo Vivian: The electricity produced by the internal combustion engine can
28:34:950Jacopo Vivian: partial is partially sold to the grid, and partially
28:38:880Jacopo Vivian: we let supply the electricity to the compressor of those food pumps.
28:44:840Jacopo Vivian: Okay?
28:46:310Jacopo Vivian: And during the during the heating season
28:53:620Jacopo Vivian: the heat pumps will produce water at 80 degrees. By cooling down the groundwater, and during the pulling season
29:04:680Jacopo Vivian: the heat pump will be bypassed, and the
29:11:230Jacopo Vivian: the groundwater will be directly feeding the network by the heat exchanger, because,
29:21:60Jacopo Vivian: in summer, 68 degrees are sufficient, because in summer we only have domestic hot water demand.
29:30:390Jacopo Vivian: Okay, so we have a supply temperature curve of 80 degrees in winter
29:40:430Jacopo Vivian: and depending on the outdoor temperature, lower, lower, lower, lower, lower, until 65, more or less in winter.
29:49:30Jacopo Vivian: So what is the advantage is that with this refurbishment we have.
29:56:160Jacopo Vivian: they have. They are going to completely
30:01:430Jacopo Vivian: renovate the heat supply, mix, make it it, making it greener.
30:07:780Jacopo Vivian: So in the first, st in the current situation, 60% of the heat is provided by the gas boilers
30:17:800Jacopo Vivian: and 25 by the cogeneration units and around 14% by the heat exchanger.
30:31:730Jacopo Vivian: Okay?
30:33:80Jacopo Vivian: So by by the groundwater
30:35:370Jacopo Vivian: with the future, mix with the new configuration, you have the this part that is new.
30:43:580Jacopo Vivian: There the light green is the geothermal heat pumps the 3 stage geothermal heat pump.
30:51:990Jacopo Vivian: You still have a part of the green
30:55:660Jacopo Vivian: due to the summer production of the groundwater with the heat exchanger. And so the gas boiler will be reduced from
31:06:670Jacopo Vivian: 60 to 11%.
31:09:560Jacopo Vivian: Okay covering, of course, the peak loads.
31:13:60Jacopo Vivian: Then Hector and the rest is given by gas fired
31:18:520Jacopo Vivian: by new new generation units that have higher efficiency.
31:24:740Jacopo Vivian: and they are connected to waste water back to water, to water, heat pump that they cover the waste heat from the generation unit and give also more more heat to the to the network.
31:42:790Jacopo Vivian: So with the with this configuration, the
31:48:790Jacopo Vivian: the security emissions can be reduced to 45 by 45%. Compared to the current situation.
31:59:940Jacopo Vivian: which is quite good, because then all the buildings connected will be automatically
32:07:140Jacopo Vivian: more sustainable without doing anything because they are already connected.
32:12:860Jacopo Vivian: Okay, okay, I have a few other slides. But I think it's enough
32:23:795Jacopo Vivian: we don't need to look with the seasonal storage
32:28:350Jacopo Vivian: also, because it's not very common.
32:31:400Jacopo Vivian: So tomorrow you have the last lecture with Professor Decari
32:37:360Jacopo Vivian: Monday. We have the seminar Tuesday. We have the technical list.
32:41:800Jacopo Vivian: You you all registered to the visit. Otherwise remember to do it on Google, right?
33:04:106Jacopo Vivian: By the way, last very last thing. Since this is my last lecture.
33:08:860Jacopo Vivian: remember that we have a number of thesis. If you need to make the master thesis, we have different options in the many topics that we have covered here, and also other topics. If you're interested. Just send an email or.
33:28:180Jacopo Vivian: yeah, just ask me or send me an email. And we can set the meeting to talk about it.
33:34:590Jacopo Vivian: Okay.
33:39:710Jacopo Vivian: it's a moment. There.