Review of urban thermal networks
Introduction
district heating, heat network, district heating (translation from English district heating) or teleheating is that in which heat (thermal energy) is produced in a central station and distributed through an urban network, in the same way as it is done with gas, water, electricity or telecommunications.[1][2].
What distinguishes this network from centralized building networks is that it serves a group of buildings that can be more or less large and its pipes run under the pavement of the streets or the common areas of the neighborhood. The extent of the network can be small, for a group of houses; medium or large, covering an entire population.
Morphology
From a heat production plant, a heat transfer medium, generally hot water, is distributed through thermally insulated pipes to the building substations where, with an exchanger, the water is prepared with the characteristics (pressure and temperature) of the building installation. This substation is like any building thermal power plant, but with an exchanger instead of a boiler "Boiler (heating)").
The water, which has left part of the heat it transported in the building substations, returns to the production plant to be reheated and sent back to the network.
Characteristics
The advantage of this type of heating is based on the fact that large heat producing systems have much higher efficiency than small ones, so that fuel is better used. On average, it is estimated that it has performances that are at least 10% higher than centralized building systems and between 30 and 40% higher than individual home systems, which represents great savings in greenhouse gas emissions. Furthermore, the plant's emissions are cleaner of other pollutants than those of smaller boilers, because, on the one hand, they have a system of frequent inspections and tune-ups, and on the other hand, they may have specific smoke purification systems, which are very expensive in small plants.
From a purely economic point of view it is also favorable, since the thermal power plant is a large consumer of fuel, lower fuel prices can be negotiated with suppliers.