Ways to reduce energy losses in thermal networks. Analysis of the effect of thermal insulation on the reduction of heat losses from the surface of pipelines using the example of a heat network
Today, more and more vital before every person is the question of energy conservation. Such an acute problem is solved as state level, and internationally, in the form of the introduction into the life of society of mechanisms specially created to achieve this goal, programs. One of the main components of their action is the preservation of heat in residential, public and other types of premises.The issue of heat savings is justified by three main reasons, which include:
- a significant increase in energy prices;
- reduction of natural reserves of energy raw materials from which thermal energy is generated;
- significant Negative influence emissions from the combustion of energy raw materials on climate and nature.
External thermal insulation of building walls
The main task of outdoor thermal insulation materials is to reduce heat loss and humidity in buildings. Their most important priority features are reliable effective protection external structural elements buildings and significant preservation of the internal areas of their premises. A competent approach to the choice of thermal insulation materials allows you to achieve high performance in retaining heat, even at low costs.In modern construction technologies the central technical and technological means by which the thermal insulation of external walls is performed is mineral wool. This material is made by manufacturers in the form of cotton slabs of basalt and silica, which are coated with a waterproof substance. The main method of laying this heat-insulating agent is its installation under the facing brickwork, which allows you to create a so-called ventilated layer of walls.
In the construction industry, the following main methods of wall insulation are used:
- thermal insulation with polystyrene foam - a method of sticking a special foam or applying liquid polyurethane foam on the outside walls, which can be with or without a ventilated layer;
- thermal insulation by creating the so-called "wet" type of walls - this method involves the installation of cotton slabs on the wall, on which a special reinforcing mesh is glued, and their further coating with putty material;
- external thermal insulation of the walls of the house with a ventilating layer, in which it is used to prevent the possibility of the appearance of condensate that destroys the walls, vapor barrier material and cotton slabs, with their subsequent processing facade material through a wooden crate.
Thermal insulation of heat mains
It is indisputable that, no matter what methods are used to insulate the building structures, but without thermal insulation of thermal devices, mechanisms and pipelines, the issue of heat conservation will be considered an empty phrase. especially important technical solution such a problem as reducing heat losses is the external thermal insulation of pipelines.Today, one of the most advanced technologies for insulating pipe lines is the creation of a special heat-insulating shell made of expanded polystyrene. The diameter and thickness of such an insulating material are made by manufacturers based on existing pipe sizes and on an individual order.
Efficiency in reducing heat losses when used as a heater for pipes of an insulating shell is achieved by its special characteristics:
- high degree of water resistance;
- resistance to different types decay processes (fungi, mold).
Heat loss in buildings
Arise artificially good conditions transfer of heat from heating devices to building enclosing structures when using a common method of fastening heating batteries to Wall. We are talking about driving hanging hooks or using embedded anchor bolts. The presence of such metal in the wall creates easier ways for heat to move out. Even close proximity to the riser wall internal system apartment heating also contributes to increased heat transfer to the outside (Fig. 4). It turns out that it is important to very strictly evaluate the gap between the riser and the wall and recommend its value to the builders. Or maybe it is possible to attach the risers to the inner wall of the apartment wall, and not to the outer one. Although apartment-by-apartment heat metering schemes exclude apartment risers, so-called driveways appear, with which the mentioned situation should be avoided.
Well-known to builders and operators of the scheme of the lower or upper wiring of the heating network water inside a residential building. This is when the network water cools down in high-rise building from bottom to top (Fig. 5, a) and from top to bottom (Fig. 5, b). With the actual disorder of the intra-house network and frequent failure to maintain the temperature of the supply network water (tn) according topattern "a" can be hot on the lower floors and cold on the upper ones. According to the scheme "b", everything is vice versa at the same temperature of the return network water (to).
A mixed scheme is also known. It is important to use the latter not in general, as it is done today, but purposefully to maintain comfortable temperatures targeted at the height of the whole house inside corner apartments, which are characterized by increased heat transfer to the outside. In general, in such rooms and apartments, mixed scheme will be average enough heat heating network water on all floors of the house, approaching the calculated one (Fig. 5, c), and not the same as indicated above according to the scheme "a" and "b". This can reduce discomfort in corner and disadvantaged apartments and cut down on overheating losses in other warmer spaces.
Thus, the listed facts suggest solutions for more efficient use of heat. On the other hand, direct losses of thermal energy directly increase the planet's greenhouse effect and accelerate global climate warming. There is an intertwining of environmental and economic issues, which obliges us to save energy from a civil position in order to preserve the nature around us and reduce human diseases.
1. Sketch fixed support pipeline.
2. Intermediate thermogram sliding support heating pipelines.
3. Sketch of a movable support with a minimum outflow of heat.
Fig. 4. Schemes for cooling heating network water in a 6-storey building: a - with upper wiring, b - c lower wiring, in - with mixed wiring.
With analysis Russian market thermal insulation you can find in the report of the Academy of Conjuncture Industrial Markets"The market of heat-insulating materials in Russia".
Ph.D. V.I. Ryabtsev, corresponding member. MAN, Associate Professor, Kursky Technical University; Ph.D. M.A. Litvinenko, engineer; A.N. Pletnev, engineer; G.A. Ryabtsev, Engineer, Kursk Municipal Heating Networks
The amount of fuel consumed by the energy system largely depends on the losses of heat and electrical energy. The higher these losses, the more fuel will be required, all other things being equal. Reducing electricity losses by 1% will save 2.5–4% of fuel resources. One of the ways to help reduce the loss of heat and electricity is the introduction of APCS and ASKUE.
The main reason for the loss of thermal energy is the low coefficient of performance (COP) of thermal power plants. Currently, the depreciation of power plants at Belarusian power plants is about 60%, and the pace of renewal of fixed assets in the energy sector lags behind the pace of aging of previously commissioned capacities. For this reason, a significant part of the main equipment has already worked out the expected service life. The equipment of large thermal power plants and state district power plants in Belarus today corresponds to the average foreign level of the 1980s. The efficiency at our condensing power plants is no more than 40% at full load of power units, and at partial load it is even lower. At CHP power plants in heating season and when the power units are fully loaded, the efficiency is approximately 80%, in the non-heating season and when the power units are not fully loaded, it is approximately 50%. A significant part of the heat is lost in the boilers. In old boilers, the efficiency is about 75%. When they are replaced with new, more advanced boiler units, the efficiency of the boiler part increases to 80–85%. However, this does not fundamentally solve the problem of reducing thermal energy losses.
Boilers are also being converted into mini-CHPs. In these works, gas turbine, gas piston engines and waste heat boilers are used. The use of a frequency electric drive can significantly increase the efficiency of thermal power plants and boiler houses.
To reduce heat losses in heating networks, pre-insulated pipes (PI-pipes) began to be used. Thanks to their use, heat losses are reduced by about 10 times compared with the use of conventional steel pipes with thermal insulation of 120 W/m.
One of the ways to reduce heat energy losses is also the transition from a centralized heat supply system to a decentralized one, in which there is no heat consumption from a CHPP or from a central boiler house through heating networks.
A lot of heat "leaves" through the walls, floors, ceilings, windows and doors of old buildings and structures. In old brick buildings, losses are approximately 30%, and in buildings made of concrete slabs with built-in radiators - up to 40%. Heat losses in buildings also increase due to the uneven distribution of heat in rooms, so it is advisable to equalize the temperature difference (floor - ceiling) using ceiling fans. Due to this, heat loss can be reduced by up to 30%. To reduce heat leakage from the premises, it is desirable to make an air curtain.
Heat regulation also helps to reduce the loss of thermal energy in the premises, taking into account the orientation of the house in parts of the world, which we have not done yet.
Over time, it is expected to introduce into the energy sector highly economical diesel and gas turbine installations of medium and low power, high-intensity heat generators for electricity and heat supply to individual houses and small businesses. It is also planned to use fuel cells and heat pumps to generate heat, cold and electricity.
Foreword
There are several reasons for heat loss in the house, and each of them can be, if not completely eliminated, then at least partially localized. According to Gosstroy research, two-thirds of the energy generated in the country "dissolves into thin air."
Content
There are several reasons for heat loss in the house, and each of them can be, if not completely eliminated, then at least partially localized. According to Gosstroy research, two-thirds of the energy generated in the country "dissolves into thin air." Before reducing heat loss at home, you need to find out why the street is heated instead of heating the room and, despite the fire batteries, it is cold in the apartment.
You can understand how a house loses heat if you remember some physical laws.
The main causes of heat loss at home are the following factors:
- conductivity. Since the house is built on cold ground, due to thermal conductivity heat flows go into the soil;
- convection. When the heating is switched on, the walls and the roof become warm from the inside. As a result of the action of thermal conductivity, heat also moves to the outer side of the walls and roof. At the same time, the atmosphere surrounding them, being colder, heats up due to them and takes away part of the heat, taking it up.
Thus, we can say that the thermal conductivity of building materials and the difference between the temperatures in the house and on the street are the two main factors affecting the loss of heat in the house.
At the same time, the main heat losses occur through the enclosing structures of the house: 35% of heat loss falls on the walls, 25% on the roof, 15% through the basement ceiling and all kinds of cracks, and 10% through windows. A certain part of the heat can be taken out of the house.
To establish which of them is to blame for the fact that the house is cold, despite the fiery batteries, a special examination called thermal imaging diagnostics. If you invite services that specialize in it, then the survey will reveal specific places of heat leaks; quality, defects and damage to the thermal insulation of the attic and basement ceilings and pipes; cold bridges; condition, etc.
How to reduce heat loss at home: thermal insulation of walls and windows
Understanding the causes of heat loss raises a natural question: how to eliminate heat loss at home, at least significantly reduce it? The answer is obvious - to radically improve the thermal insulation of walls, roofs, ceilings, windows, which will increase the temperature in the house without increasing heating costs.
With high-quality thermal insulation of the house, even if the air temperature drops to -25 ° C and the heating is turned off, the temperature inside the house will drop by only 1 ° C per day. It is clear that the cost of heating in such a house is not so burdensome.
If you do not know how to reduce heat loss at home, start by inspecting the windows: check the opening and closing mechanisms, adjust them if necessary. If gaps are found between window blocks and walls, they also need to be hermetically sealed. The glass can be coated with a reflective coating. It will help reduce heat loss and glazing of balconies and loggias.
Another way to reduce heat loss at home is to insulate the doors, and it is advisable to install a second door, which will additionally play the role of a sound insulator.
How to reduce heat loss at home: roof and basement insulation
In addition, the walls, roof and basement must be insulated. At the same time, it should be noted that it is necessary to insulate the house not from the inside, but from the outside. If you do this from the side of the room, then between the wall and internal thermal insulation condensation will accumulate, which will not only worsen the thermal insulation of the house, but also lead to damage to the finish and the reproduction of fungi. For external thermal insulation, a material such as extruded polystyrene foam is suitable; the device of a ventilated facade has proven itself well, etc.
For thermal insulation of roofs, as a rule, stone or mineral wool, which are implemented in the form of plates. At the same time, one should not forget about the vapor barrier (it is desirable that its side facing inward be covered with aluminum foil, which will prevent heat loss from radiation).
If the house is still in the project, then it is necessary to think in advance about how to reduce the perimeter of the external cold walls (the larger the square of the external walls, the greater the heat loss; the house, decorated with numerous protruding elements, loses a lot of heat), to prevent the formation of cold bridges.
Reducing heat loss at home: the construction of the attic
The construction of an attic is another way to reduce heat loss at home and reduce heat loss through the roof, since part of it is used as walls. attic room. About what to choose for the roof quality material, perhaps, you can not speak.
It is unlikely that it will be possible to reduce the heat loss of the house to zero, but it is realistic to take measures due to which it is possible to stop heating the street. The first thing that comes to mind is the need to insulate the house. At the same time, we note that the cost of thermal insulation compared to how much it will cost to build a house is simply miserable. Savings on thermal insulation will certainly turn into more heavy losses in the future, especially since energy prices are constantly rising. Approaching the insulation of the house in the complex, you can reduce heating costs by about 40%. This means that thermal insulation is doubly beneficial, as it reduces heat loss and minimizes energy costs.
Reducing heat loss at home: thermal insulation materials
Thermal insulation materials must meet a number of requirements, including:
- durability (this is important for its long-term operation);
- environmental friendliness (absence of emissions harmful to health);
- combustibility (hence the fire safety);
- increased vapor permeability (due to which moisture will be removed from the room and the structures of the house will remain dry);
- light weight (you don’t have to, there will be no problems with installation, transporting material and buying fasteners will not cost too much
- naturally, the price (for many, this is the main indicator that determines).
In order to offer effective measures to improve the efficiency of the use of thermal energy in a building, it is necessary to correctly compose and calculate the heat balance of the building and assess its energy efficiency. The heat balance includes the heating load of the building, which is affected by heat losses through the building envelope, heat losses for heating the infiltrating air, heat losses for heating the ventilation air, heat release from solar radiation through light openings and internal household heat release.
Practice shows that 40...50% of all heat losses are due to the heating of infiltrating and ventilation air, about 20...30% of heat is lost through light openings, and only about 30% is heat loss through external walls, floors and coatings.
Currently, settlements between the consumer and the supplier of thermal energy are made according to the old heating norms, which do not take into account the share of the total heat output of the building, taking into account heat gain from solar radiation, while it reaches 20% of the total heat loss in residential and public buildings. This leads to excessive release of heat, which is thrown out through the vents.
After item-by-item determination of the proportion of heat losses of the building and its specific thermal characteristics, it is possible to assess the energy efficiency of the building and propose energy-saving measures that will lead to significant savings in thermal energy.
Table 9.2
|
Reduction of heat losses in buildings |
||
|
Reducing heat loss with infiltrating air by sealing doors and window joints | ||
|
Reducing transmission losses through window openings by installing a third glass or PVC film in the inter-frame space of windows | ||
|
Improving the thermal insulation of walls, floors and attics | ||
|
Withdrawal decorative fences from heating radiators and installation of heat reflectors behind radiators | ||
|
Arrangement of ventilated external walls | ||
|
Additional insulation of external walls during the reconstruction of buildings | ||
|
Applying intermittent heating | ||
|
Rotating regenerative air-to-air heat exchangers | ||
9.3.2. Regulation of heat consumption in heating points.
Table 9.3
|
Heat points |
||
|
Equipping heating systems with cost meters |
10-100% of heat energy consumption |
|
|
Reducing heat consumption by automating heating systems by installing individual heating points (ITP). |
20-30% of heat energy consumption |
|
|
Drawing up guidelines for the operation, management and maintenance of heating systems and periodic monitoring by the management of the institution for their implementation |
5-10% of heat energy consumption |
|
|
Equipment DHW systems hot water meters |
10-20% of consumption hot water |
|
Energy saving in lighting systems
All over the world, outdoor, domestic and industrial lighting consumes a significant part of the electricity produced. For Russia, the relevance of solving the problem of reducing the cost of artificial lighting is determined by the high consumption of electricity per million inhabitants (more than 1.5 times than in the UK and Japan) and the presence of a shortage of electricity in a number of regions of the country. Saving electrical energy in lighting can be achieved both by reducing the installed power and by reducing the time of use of lighting equipment.
We present data on the efficiency of radiation sources in terms of energy savings and service life. The efficiency of using electricity (H) is primarily determined by the luminous efficiency of the radiation sources used, equal to the ratio of the luminous flux of the lamp (lm) to its power (W). The following table shows the luminous efficacy and average term service in hours of various types of light sources most common at present.
Table 9.1
Here: LN - incandescent lamps; GLN - halogen incandescent lamps; LL - fluorescent lamps; CFL - compact fluorescent lamps; DRL - arc mercury lamps; MHL - metal halide lamps; HPS - high pressure sodium lamps.
It can be seen from the table that compact fluorescent lamps and incandescent lamps used in everyday life differ in light output by about 5 times, i.e. to obtain the same luminous flux for compact fluorescent lamps, five times less electricity is required. Over its lifetime, one 20 W compact fluorescent lamp saves, compared to an incandescent lamp, 800 kWh of electricity, which would require 250 kg of coal or 200 liters of fuel oil to generate. Nevertheless, in our country, compact fluorescent lamps are used to a limited extent. There are two reasons: high price and limited edition of these lamps.
The advantages of modern light sources can be fully realized with the appropriate ballasts. Currently, to turn on light sources, both electromagnetic ballasts (EMPR, conventional, with reduced losses, with minimized losses) and electronic ballasts (electronic ballasts, uncontrolled and controlled) are used.
The advantages of EMPRA include extremely high reliability and relatively low cost.
The advantages of "lamp-electronic ballast" kits include:
almost complete absence of lamp luminous flux pulsations, which makes it possible to use these kits for lighting rooms with heavy visual work;
high luminous efficacy of the "KLL - ballast" set, reaching the luminous efficacy of the lamps themselves when they operate at a frequency of 50 Hz, which makes it possible to save electricity in the lighting installation by 25%;
30-40% longer lamp life when working with electronic ballasts, compared with EMPR;
the ability to control the luminous flux of lamps when working with electronic ballasts.
However, with the implementation of these opportunities, the potential for reducing the installed capacity of artificial lighting in public buildings is very limited. For example, the best light sources currently used for indoor lighting of public buildings have practically reached the “ceiling” of 96–104 lm/W in terms of luminous efficacy, and for modern types of luminaires, the actual values of the efficiency are 70–80% and the reserve for its increase is practically exhausted. Finishing materials with high (up to 0.8) reflection coefficients are increasingly being used.
However, a significant reduction in electricity consumption in lighting installations is possible. The analysis shows that, for example, in the energy consumption structure of public buildings, the share of energy consumption for lighting purposes reaches 70%, while a clear personal responsibility and material interest in saving electricity is difficult to implement. In this case, energy consumption can be optimized through the use of automated control systems. Lighting control systems maintain the required (normalized) levels of illumination during the operation of the lighting installation in accordance with a given program, eliminating excessive energy consumption.
When using a lighting control system, energy savings are achieved due to several factors.
Firstly, in the initial period of operation of fluorescent lamps, as well as with an excess (for construction, structural, architectural or other reasons) number of lamps, the illumination created in the room is overestimated and can automatically decrease to the required value, which, according to estimates, reduces energy consumption by 15–25 %.
Secondly, the most significant energy savings can be ensured by the rational use of natural light(transition from artificial lighting to combined), since for a sufficiently long time of the day the lighting can be turned off altogether or turned on at a minimum power (1–10% of the nominal). Savings can reach 25-40%.
Thirdly, the hourly operating time of the lighting installation in the absence of automatic control also exceeds rational values, since with spontaneous control, artificial lighting remains switched on with sufficient natural light and the absence of people in the illuminated premises, as well as after hours due to the forgetfulness of the staff.