The KAN-therm system is intended for internal equipment of cold and hot water supply, as well as central and underfloor heating from LPE, PE-Xc, PE-Xc/AL/PE-Xc pipes.

Regulation of heat consumption of buildings - real heat savings

1. What determines energy consumption?

Energy consumption is primarily driven by heat losses from the building and is aimed at compensating them in order to maintain the desired level of comfort.

Heat loss depends on:
from the climatic conditions of the environment;

from the design of the building and from the materials from which they are made;

from the conditions of a comfortable environment.

Part of the losses is compensated by internal energy sources (in residential buildings, this is the work of the kitchen, household appliances, lighting). The rest of the energy losses are covered by the heating system. What potential actions can be taken to reduce energy consumption?

• limiting heat loss by reducing the thermal conductivity of the building envelope (window sealing, wall and roof insulation);
• maintaining a suitable constant, comfortable room temperature only when there are people there;
• lowering the temperature at night or during a period when there are no people in the room;
• improving the use of " free energy» or internal heat sources.

2. What is a favorable room temperature?

According to experts, the feeling of "comfortable temperature" is associated with the body's ability to get rid of the energy it produces.

In normal humidity, the feeling of "comfortable warmth" corresponds to a temperature of about +20°C. This is the average between air temperature and temperature inner surface surrounding walls. In a poorly insulated building, the walls of which have a temperature of +16°C on the inside, the air must be heated to a temperature of +24°C in order to obtain a favorable temperature in the room.

Tcomf = (16 + 24) / 2 = 20°C

3. Heating systems are divided into:

Closed, when the coolant passes through the building only through heating devices and is used only for heating needs; open when the coolant is used for heating and for hot water needs. As a rule, in closed systems, the selection of coolant for any needs is prohibited.

4. Radiator system

Radiator systems are single-pipe, two-pipe and three-pipe. Single-pipe - are used mainly in the former republics of the USSR and in Eastern Europe. Designed to simplify the piping system. There is a great many single pipe systems(with top and bottom wiring), with or without jumpers. Two-pipe - have already appeared in Russia, and previously had distribution in Western Europe. The system has one inlet and one outlet pipe, and each radiator is supplied with a coolant with the same temperature. Two-pipe systems are easy to adjust.

5. Quality regulation

The existing heat supply systems in Russia are designed for constant consumption (the so-called quality regulation). Heating is based on a system with dependent connection to mains with a constant flow rate and a hydraulic elevator, which reduces static pressure and temperature in the pipeline to the radiators by mixing return water(1.8 - 2.2 times) with the primary flow in the supply pipeline.
Disadvantages:
the impossibility of taking into account the real need for heat in a particular building under conditions of pressure fluctuations (or pressure drop between supply and return);
temperature control comes from one source (thermal plant), which leads to distortions in the distribution of heat throughout the system;
large inertia of systems with central temperature control in the supply pipeline;
in conditions of pressure instability in the quarterly network, the hydraulic elevator does not provide reliable circulation of the coolant in the heating system.

6. Modernization of heating systems

Modernization of heating systems includes the following activities:
Automatic control of the temperature of the heat carrier at the inlet to the building, depending on the outside temperature, with the provision of pumped circulation of the heat carrier in the heating system.
Accounting for the amount of heat consumed.
Individual automatic control of heat transfer of heating devices by installing thermostatic valves on them.

Let's take a closer look at the first item.

Automatic control of the coolant temperature is implemented in the automated control unit. circuit diagram one of options node construction is shown in Figure 1. There are quite a few varieties of node construction schemes. This is due to the specific structures of the building, heating system, various operating conditions.

Unlike elevator units installed on each section of the building, automated node it is advisable to install one per building. In order to minimize capital costs and facilitate the placement of the node in the building, the maximum recommended load on the automated node should not exceed 1.2 - 1.5 Gcal / h. For larger loads, it is recommended to install double, symmetrical or asymmetrical load units.

Basically, an automated node consists of three parts: network, circulation and electronic.
The network part of the unit includes a coolant flow regulator valve, a differential pressure regulator valve with a spring regulating element (installed if necessary) and filters.
The circulation part consists of a circulation pump and check valve(if a valve is required).
The electronic part of the assembly includes a temperature controller (weather compensator) that maintains the temperature graph in the building heating system, an outdoor temperature sensor, coolant temperature sensors in the supply and return pipelines, and a geared electric drive for the coolant flow control valve.

Heating controllers were developed in the late 40s of the XX century and, since then, only their design has fundamentally differed (from hydraulic ones, with mechanical clocks, to fully electronic microprocessor devices).

The main idea behind the automated node is to maintain heating schedule temperature of the heat carrier for which the heating system of the building is designed, regardless of the outdoor temperature. Maintaining the temperature graph along with stable circulation of the coolant in the heating system is carried out by mixing required amount cold coolant from the return pipeline to the supply pipeline using a valve with simultaneous control of the temperature of the coolant in the supply and return pipelines of the internal circuit of the heating system.

The joint activity of the employees of CJSC PromService and PKO Pramer (Samara) in the development of heating controllers led to the creation of a prototype of a specialized controller, on the basis of which a heat supply control unit was created in 2002 administrative building CJSC "PromService" for testing the algorithmic, software and hardware parts of the controller controlling the system.

The controller is a microprocessor device capable of automatically controlling heating units containing up to 4 heating and hot water circuits.

The controller provides:

Account of the time of operation of the device from the moment it was turned on (taking into account the power failure, no more than two days);
conversion of signals from connected temperature transducers (resistance thermometers or thermocouples) into air and coolant temperature values;
input of discrete signals;
generation of control signals for controlling frequency converters;
generation of discrete signals for relay control (0 - 36 V; 1 A);
generation of discrete signals for power automation control (220 V; 4 A);
display on the built-in indicator of the values ​​of the system parameters, as well as the values ​​of the current and archived values ​​of the measured parameters;
selection and configuration of system control parameters;
transfer and configuration of system parameters of work via remote communication lines.

By measuring the parameters of the system, the controller controls the thermal regime of the building by acting on the electric actuator of the control valve (valves) and, if provided by the system, on the circulation pump.

The regulation is implemented according to a predetermined heating temperature curve, taking into account the actual measured values ​​of the temperatures of the outside air and the air in the control room of the building. In this case, the system automatically corrects the selected graph, taking into account the deviation of the air temperature in the control room from the set value. The controller ensures that the heat load of the building is reduced to a given depth in a given period of time (weekend and night mode). The ability to introduce additive corrections to the measured temperature values ​​allows you to adapt the operating modes of the control system to each object, taking into account its individual characteristics. The built-in two-line indicator provides a view of the measured and set parameters through a simple and understandable user menu. Archived parameter values ​​can be viewed both on the indicator and transferred to a computer via a standard interface. The functions of self-diagnostics of the system and calibration of measurement channels are provided.

The heat supply metering and control unit of the administrative building of CJSC PromService was designed and installed in the summer of 2002 on a closed heating system with a load of up to 0.1 Gcal / h with a single-pipe radiator system. Despite the relatively small dimensions and number of storeys of the building, the heating system contains some features. At the outlet of the heating unit, the system has several horizontal wiring loops on the floors. At the same time, there is a division of the heating system into circuits along the facades of the building. Commercial metering of consumed heat is provided by the SPT-941K heat meter, which includes: resistance thermometers of the TSP-100P type; flow converters VEPS-PB-2; heat calculator SPT-941. For visual control of the temperature and pressure of the coolant, combined pointer devices Р/Т are used.

The control system consists of the following elements:
controller K;
rotary valve with PKE electric drive;
circulation pump H;
coolant temperature sensors in the supply T3 and return T4 pipelines;
outdoor temperature sensor Tn;
air temperature sensor in the control room Тк;
filter F.

Temperature sensors are necessary to determine the actual current temperature values ​​for the controller to make a decision about controlling the PKE valve based on them. The pump ensures stable circulation of the coolant in the heating system of the building at any position of the control valve.

Focusing on thermal parameters heating system (temperature curve, pressure in the system, working conditions) a rotary three-way valve HFE with electric drive AMB162 manufactured by Danfoss. The valve provides mixing of two coolant flows and operates under the following conditions: pressure - up to 6 bar, temperature - up to 110°C, which fully corresponds to the conditions of use. The use of a three-way control valve made it possible to abandon the installation of a check valve, traditionally installed on a jumper in control systems. As a circulation pump, a sealless UPS-100 pump from Grundfos is used. Temperature sensors - standard RTD thermometers. The FMM magnetic-mechanical filter is used to protect the valve and pump from mechanical impurities. The choice of imported equipment is due to the fact that the listed elements of the system (valve and pump) have proven themselves to be reliable and unpretentious equipment in operation in rather difficult conditions. The undoubted advantage of the developed controller is that it is able to work and connect electrically with both rather expensive imported equipment and allows the use of widely used domestic devices and elements (for example, inexpensive resistance thermometers compared to imported analogues).

7. Some results of operation

First of all. During the period of operation of the control unit from October 2002 to March 2003, not a single failure of any element of the system was recorded. Secondly. The temperature in the working premises of the administrative building was maintained at a comfortable level and amounted to 21 ± 1 °C with outdoor temperature fluctuations from +7°C to -35°C. The temperature level in the rooms corresponded to the set one, even if the heat carrier was supplied from the heating network with a temperature lower than the temperature graph (up to 15°C). The temperature of the heat carrier in the supply pipeline changed during this time in the range from +57°С to +80°С. Thirdly. The use of a circulation pump and balancing the circuits of the system made it possible to achieve a more uniform heat supply to the premises of the building. Fourth. The regulatory system allowed, subject to comfortable conditions in the premises of the building to reduce the total amount of heat consumed.

If we consider the change in the heat supply mode during the day and week with the activated functions of the controller for lowering the temperature of the coolant at the supply at night and on weekends, we get the following. The controller allows the operating personnel to select the duration of the night mode and its "depth", that is, the amount of decrease in the temperature of the coolant relative to the specified temperature graph in a given period of time based on the characteristics of the building, personnel work schedule, etc. For example, empirically, we managed to choose the following night mode. Starting at 16:00, ending at 02:00.

Coolant temperature decrease by 10°С. What were the results? Reduced heat consumption in night mode is 40 - 55% (depending on the outdoor temperature). At the same time, the temperature of the heat carrier in the return pipeline decreases by 10 - 20 °C, and the air temperature in the premises - by only 2-3 °C. In the first hour after the end of the night mode, the “boost” mode of increased heat supply begins, in which heat consumption reaches 189% relative to the stationary value. In the second hour - 114%. From the third hour - stationary mode, 100%. The savings effect greatly depends on the outdoor temperature: the higher the temperature, the more pronounced the savings effect. For example, the decrease in heat consumption with the introduction of the "night" mode at an outdoor temperature of about -20°C is 12.5%. With an increase average daily temperature the effect can reach up to 25%. A similar, but even more advantageous situation arises when implementing “weekend” modes, when a decrease in the temperature of the coolant at the supply on weekends is set. No need to maintain comfortable temperature throughout the building if no one is in it.

findings

The experience gained in operating the control system has shown that the savings in heat consumption when regulating heat supply, even if the heat supply organization does not comply with the temperature schedule, is real and can reach up to 45% per month under certain weather conditions.
The use of the developed controller prototype made it possible to simplify the control system and reduce its cost.
In heating systems with a load of up to 0.5 Gcal / h, it is possible to use a fairly simple and reliable seven-element control system that can provide real savings funds, while maintaining comfortable conditions in the building.

Ease of operation with the controller and the ability to set many parameters from the keyboard allows you to optimally adjust the control system based on the actual thermal characteristics of the building and the desired conditions in the premises.
The operation of the control system for 4.5 months showed reliable, stable operation of all elements of the system.

LITERATURE
RANK-E controller. Passport.
Catalog automatic regulators for building heating systems. ZAO Danfoss. M., 2001, p.85.
Catalog "Sealless circulation pumps". Grundfoss, 2001

S. N. Yeshchenko, Ph.D., Technical Director CJSC PromService, Dimitrovgrad. Contacts: [email protected]

Ph.D. A.G. Batukhtin, director of the Technopark of the Transbaikal State University;
M.V. Kobylkin, post-graduate student of the Department of Thermal Power Plants, Trans-Baikal State University, Chita

Currently, technologies aimed at optimizing existing technological solutions in order to save energy are receiving more and more attention in the development of the energy sector. This approach is due both to the political strategy for the development of the Russian energy sector, which is reflected in the Federal Law No. 261-FZ "On Energy Saving and Energy Efficiency Improvement", and competition existing systems district heating under modern market relations in the energy sector. The question of increasing the competitiveness of existing thermal power plants as the basis for heating the Russian Federation is of particular relevance. At the same time, the difficult economic situation and the lack of free financial resources for generating companies make it necessary to look for low-cost methods of energy saving.

To date, many methods have been developed to optimize the supply of thermal energy from CHPPs to consumers, taking into account the peculiarities of the functioning of thermal networks, both in systems with open water intake at DHW needs, and closed .

The progressive development of technology, including electronics, has contributed to the development of complex automatic control systems. The modern automatic control system (ACS) has a number of advantages that were difficult to achieve at the beginning of the last century, when district heating was becoming established. Currently, one of the main advantages of ATS is the ability to implement complex laws of automatic control, in addition, in most standard systems the possibility of reprogramming is laid, i.e. changes in the laws of regulation and management of the system. In such conditions, automated control systems are of great relevance, allowing to minimize heat consumption, while creating comfortable temperature conditions for consumers.

Existing automated systems are able to accurately monitor many parameters, both of the heat carrier and the air inside and outside the building, and, as a result, are capable of regulating heat consumption to a sufficient high level. However, such systems include a large number of elements, the installation of which is necessary for each consumer of the system, as a result of which the main disadvantage of such systems is significant capital costs and maintenance costs when introducing automation for a group of consumers.

To solve the problem of equipment costs, it is proposed to introduce a patented automated system for regulating the flow of coolant for heat supply to consumer groups (Fig. 1), in which a complete set of automation is installed only on the consumer with the maximum heat load (automated consumer), on the remaining consumers of the system (non-automated consumers) install only indoor air temperature sensors and coolant flow sensors.

Rice. 1. Automated coolant flow control system:

1 - heat source, 2 - automated consumer, 3 - non-automated consumer, 4 - heat and power processor (TEP), 5 - supply pipeline, 6 - return pipeline, 7 - coolant flow sensor, 8 - coolant flow regulator, 9 - automated consumer sensor complex , which includes sensors for flow, temperature and pressure of the coolant, 10 - circulation pump, 11 - indoor air temperature sensor, 12 - outdoor air temperature sensor.

The system operates as follows: when the environmental parameters change in such a way that it becomes necessary to increase the thermal load of consumers, TEC 4 gives a signal to the flow controller 8 to increase the coolant flow to the automated consumer 2, which allows maintaining the preset temperature of the internal air of the automated consumer 2, in at the same time, manual consumer 3 begins to experience a shortage of thermal energy, which leads to a gradual decrease in its internal air temperature monitored by sensor 11. When the temperature of the internal air of manual consumer 3 drops to the lower set limit, TEC 4 sends a signal to flow controller 8 to reduce consumption coolant to the automated consumer 2, which leads to an increase in consumption for non-automated consumer 3 due to an increase in pressure in the heating network. The decrease in consumption for an automated consumer is carried out until the consumption for non-automated consumer 3 reaches the minimum required value.

Using a flow sensor 7, TEC 4 monitors the change in flow to a non-automated consumer, after reaching the minimum required flow rate, TEC 4 stops sending a signal to the flow controller 8, thereby stabilizing the system, after which the non-automated consumer 3 begins to warm up, and the automated consumer 2 gradually cools down , consuming the accumulated heat. As soon as the temperature of the internal air of the non-automated consumer 3 reaches the upper set limit, or the temperature of the internal air of the automated consumer 2 drops to the lower set limit, TEC 4 returns the system to its original state.

Thus, the cost redistribution cycles make it possible to maintain the temperature regime of consumers connected to heating networks without installing additional control devices, which saves capital costs for the installation of automation devices and the cost of their maintenance.

Since the principle of operation of the scheme is based on hydraulic dependencies in heating networks, a number of restrictions are imposed on it in use, so for networks with “good” hydraulics this method will be ineffective due to the insignificant dependence between the flow rate of the coolant and the pressure drop in the heating network. But, despite this, the scheme takes on special relevance for dead-end networks with degraded hydraulic performance, which can be shown on the example of the buildings of the Transbaikal State University.

The Trans-Baikal State University has two buildings located on the same branch from the main heating network, with loads of 1.2 and 0.3 Gcal / h, respectively, for the first and second buildings. After carrying out measures to automate the first building, it was noticed that with an increase in the load on the first building, the second building begins to experience a shortage of thermal energy, in connection with which a project was proposed to automate the second building to reduce the resulting deficit, the cost of which is about 900 thousand rubles.

In the course of a series of experiments, it was found that under existing hydraulic conditions and with design parameters, a change in the flow rate of the first consumer by 8 t/h leads to a change in the flow rate of the second consumer by an average of 1 t/h, which, under appropriate loads, gives large range for regulation, thereby allowing the implementation of the above scheme. Moreover, the cost of upgrading the existing scheme, in which the first building already has a full range of automation, to the above is about 20 thousand rubles. Thus, the introduction of this automated control system will reduce capital costs by 97.7% of original cost project.

In addition to the local use of the system for specific buildings, the above principle of regulation can be implemented in a wider framework. So, in the conditions of modern urban development, not only single buildings with an automated heating system, but also microdistricts consisting of dozens of buildings with modern automation join the district heating networks. The operation of the automation of such microdistricts in many cases has a rather strong hydraulic effect on the remaining consumers of the system located at a great distance from each other, which can lead to a shortage of heat in some areas of the city. The principle of regulation in such a case can be demonstrated by the example of the heating networks of the city of Chita.

The Oktyabrsky microdistrict with a total heat load of 14 Gcal / h, which has an integrated automation system with single center management for the entire area. When regulating the load on a microdistrict scale, a significant change in costs in the heating networks of the city is inevitable, and taking into account their length, such regulation leads to a change in the available pressure for other consumers (especially for end consumers with insufficient pressure).

The first step, before applying the principle of automatic regulation of consumer groups, is to determine the area that will be most affected due to changes in load in the Oktyabrsky microdistrict. The influence of the Oktyabrsky microdistrict is determined on the basis of the hydraulic calculation of the heating network of CHPP-1 - City with a variable load on the microdistrict. Having a significant number of consumers in the heat supply system, it is advisable to carry out hydraulic calculation using modern systems mathematical modeling of heating systems. Creation as close as possible to real-life hydraulic conditions The mathematical model of the heating network of CHPP-1 - City made it possible to evaluate and compare the impact of changes in the load of the microdistrict for all consumers of the system. According to calculations, Oktyabrsky has the greatest impact on the Sosnovy Bor microdistrict with a total heat load of 26.5 Gcal / h, located at a distance of about eight kilometers from Oktyabrsky. Moreover, a change in the load of Oktyabrsky by 50% in the direction of decrease or increase leads to a change in the available pressure in front of the Sosnovy Bor microdistrict by an average of 20% of the calculated value, which indicates a strong hydraulic dependence of the microdistricts.

The next step is to install a flow sensor in front of the Sosnovy Bor microdistrict, as well as install indoor air temperature sensors in controlled buildings, and provide communication between the sensors in Sosnovy Bor and a single controller in Oktyabrsky. The installation of indoor air temperature sensors is optional for all buildings in the microdistrict, it is enough to install sensors on buildings that are in the worst conditions, thus, having provided these buildings with heat, we will certainly provide heat to the rest of the buildings in the microdistrict. The choice of controlled buildings can also be carried out on the basis of calculations in a mathematical model.

After installing the sensors and creating a connection between them and the controller, it becomes possible to carry out the process of regulating the flow of the coolant, similar to the method described above for a group of buildings.

The use of interconnections between remote consumers (automated and non-automated) allows for high-quality heat supply to the “problem” area of ​​heat consumption. The use of periodic heating, taking into account the unevenness during the day of the influence of automation of the microdistrict. "Oktyabrsky" for the mode of operation of the heating network (6 hours instead of 24) saves about 3.4 million rubles. for the heating season.

In conclusion, it can be noted that the use of this hydraulic dependence in practice for such large areas of heat consumption was a forced measure (although it was characterized by a significant economic effect). Based on the identified thin spots in the district heating system, a number of measures were developed to reduce such a strong impact, as a result, an additional pumping station was installed in Sosnovy Bor (TK-2-27), and the existing one was upgraded. Thus, an automated system for controlling the flow of heat carrier for heat supply to consumer groups, being an alternative solution, can significantly save not only capital costs, but also the costs of further maintenance.

Work on the development of energy-efficient district heating systems is carried out within the framework of the Federal Target Program "Scientific and Scientific and Pedagogical Personnel of Innovative Russia" for 2009-2013, as well as a grant from the President of the Russian Federation to support young scientists, candidates of science.

Literature

1. Batukhtin A.G. Optimization of heat supply from CHP based on mathematical modeling, taking into account the operation various types consumers: abstract. dis. cand. tech. Sciences / A.G. Batukhtin. - Ulan-Ude: VSGTU, 2005. - 16 p.

2. Makkaveev V.V. Practical use some methods of optimization of heat supply regimes / V.V. Makkaveev, O.E. Kupriyanov, A.G. Batukhtin// Industrial energy. 2008. - No. 10 - S. 23-27.

3. Batukhtin A.G. Application of optimization models for the operation of heat supply systems to reduce the cost of thermal energy and increase the available power of the station / A.G. Batukhtin, V.V. Makkaveev // Industrial Energy, 2010. - No. 3. P. 7-8.

4. Makkaveev V.V. Mathematical model of a number of subscriber inputs of closed heat supply systems / V.V. Makkaveev, A.G. Batukhtin // Scientific and Technical Bulletin of St. Petersburg State Polytechnical University, 2009, No. 3. - St. Petersburg. - S. 200-207.

5. Bass M.S. A complex approach to the optimization of the functioning of modern heat supply systems / M.S. Bass, A.G. Batukhtin//Heat power engineering, 2011, No. 8. - S. 55-57.

6. Batukhtin A.G. Methods for increasing the efficiency and increasing the available capacity of district heating systems / A.G. Batukhtin // Scientific problems of transport in Siberia and the Far East, 2010. - No. 1. - P. 189-192.

7. Batukhtin A.G., Kobylkin M.V., Kubryakov K.A. Automated control system for heat carrier flow for heat supply to a group of consumers // Patent of Russia No. 2516114. 2014. Bull. No. 14.

Equipment additional equipment traditional heating systems can significantly increase their efficiency without radical reconstruction during the modernization of the housing stock.

Potential of heating systems

For a water heating system, an energy-efficient level of heat consumption can be achieved with the following set of functions and capabilities:
- automatic maintenance of the temperature graph at the entrance to the building;
- regulation of heat transfer of the system, including thermo-regulation on heating devices and risers;
- automatic maintenance of the required/calculated distribution of the coolant flow over all sections of the system;
- individual heat metering, motivated by payment according to actual consumption.

According to the design, the following main options for energy-efficient heating systems can be represented:
- a system with horizontal apartment-by-apartment piping with various design options for apartment heating substations or switchboards, including combinations of automatic control, heat exchangers for heating and / or hot water circuits, etc.;
- a traditional heating system with vertical intra-apartment risers - one-pipe and two-pipe, comprehensively equipped with automatic control and heat metering devices.

Others are possible design options systems and their combinations.
For systems with horizontal wiring, the energy efficiency potential and the set of equipment that provides the standard level of heat consumption are obvious and described in the works of many specialists. At the same time, the potential for increasing the energy efficiency of traditional vertical heating systems is not yet obvious to many specialists. However, it is very significant, and the possibility of upgrading such systems should be considered in more detail, because:
- these systems are the most widely used, especially in the existing housing stock;
- the radical constructive transformation of such systems into horizontal ones during the modernization of the building is too costly.

Modernization of the coolant inlet to the building

The most important element of the heating system of any design is the coolant inlet to the building. The most energy-efficient input solutions are an automated control unit (AUU, a variant of a dependent heating system connection scheme) or an individual heating point (ITP, a variant of an independent connection scheme with heat exchangers of the heating circuit and hot water supply). These devices ensure compliance with a temperature schedule that is adequate to the outdoor temperature and the current heat consumption of the building, as well as reliable pump circulation of the coolant in the heating system.

The economic effect from the use of these devices ranges from 10 to 30%, depending on the compliance of the state of the building with design solutions and on the conditions of its operation.

A number of alternative ACs are known technical solutions input node, such as:
- coolant mixing unit with elevators with constant or variable mixing ratio;
- unit without mixing the coolant - used when a coolant is supplied to the building with a temperature equal to the design temperature in the heating system.

In our opinion, the use of these devices and technical solutions in energy-efficient heating systems is unacceptable. The technical reasoning that skillfully substantiates the inadequacy of such solutions for modern heating systems has long been known. However, for various reasons, criticism is not always taken into account.

A single application of such solutions leads to problems in one particular building. But when the assumption about the use of an elevator is included in the regulations, in particular, in the updated HVAC SNiP, as is done now, this is a more serious mistake that will lead to massive excesses of the standardized level of energy efficiency in newly erected and modernized buildings.

In confirmation of these words, one can refer to the work of colleagues from VTI, in which a number of possible schemes for automated elevator mixing units are analyzed. The paper considers in detail the main disadvantages of each of the schemes. A common drawback of all schemes is the fact that in order to ensure adequate performance of such devices, it is necessary to maintain a constant and small hydraulic resistance in the heating system. However, these requirements are practically impracticable if there are thermostats and other automatic control valves in the heating system.

It should also be noted the negative operational practice of using such elevators.

Maintaining the design distribution of the coolant flow

This event eliminates overflows or heat shortages on individual risers of traditional vertical heating systems. This possibility is ensured by the installation of automatic balancing valves on the risers, maintaining a constant pressure drop in the risers. two-pipe systems or constancy of flow in the risers of single-pipe heating systems.

For vertical two-pipe heating systems, this event does not raise questions among specialists, however, regarding a one-pipe system, a number of specialists express doubts about its relevance.

These doubts are based on the following:
- a significant number of vertical single-pipe systems, especially in typical housing construction, are calculated using the method of variable (sliding) temperature differences, which theoretically should ensure the hydraulic balance of the risers;
- in single-pipe heating systems, even when thermostats are triggered, a constant coolant flow is maintained, i.e. automated control and adjustment of risers are not required.

For each of these statements there is a fairly simple counterargument. In particular, according to the first statement: the design limitations of this method are known from the literature, which do not allow balancing the risers accurately enough. Also, the statement about the constancy of the flow rate with a leakage coefficient of the order of 0.25 and with a change in the flow rate of the coolant associated with a change in the gravitational pressure in the risers is also incorrect. All this is quite convincingly shown in detailed calculations performed by Ukrainian specialists.

However, all these design effects are offset by the influence of errors and assumptions introduced into the heating system on a massive scale during its design and installation, as well as changes in the design of the system made by residents within the apartment.

The results of a survey of typical sectional buildings showed a spread in the flow rate of the coolant at the control risers within ± 30% relative to the design values. After the balancing valves were installed and adjusted to the design values, the imbalance did not exceed ±3%.

As a result, the heat consumption of buildings decreased by 7-12% due to the reduction of unreasonable ventilation in rooms on "overheated" risers and adjustment of the automation settings of the input unit, which protect "lagging" risers (Fig. 1).

Rice. 1. Differences in the operation of thermostats

Thermal control of risers as a means quality regulation heat transfer

The next step in improving the energy efficiency of a traditional single-pipe heating system is to ensure quantitative regulation of the heat transfer of the system not only at the level of heaters using thermostats, but also on the risers by installing temperature controllers at the root of the risers, structurally combining them with balancing valves (Fig. 2). The effect is achieved by reducing the coolant flow through a specific riser, the temperature of the coolant in which rises as a result of closing the thermostats with excess heat in individual rooms.

Rice. 2. Thermal control of risers of single-pipe heating systems

The results of the operation of the thermostat on one of the control risers are shown in Figure 3. The graphs show a decrease in the coolant flow in the riser as a result of an increase in the coolant temperature in it as a result of closing thermostats on individual heaters. At the same time, the air temperature in the control room does not change.

Rice. 3. Energy efficiency of automatic balancing risers

The setting values ​​for these devices are determined by surveying the building and identifying the potential sources of excess heat. The most effective are "permanent" thermostats with an electric drive and an automatic control system for the temperature of the coolant in the risers.

The economic effect of the use of thermal control of risers depends on the amount of excess heat entering the building not taken into account in the project, including from the excess heating surface of heating devices. According to the results of the survey of experimental buildings, the effect ranged from 8 to 12%, depending on the condition of the building.

Individual (per apartment) heat metering

Individual (per apartment) heat metering with payment according to its actual consumption is the most important factor motivating residents to save energy. Without this measure, the system of energy saving measures remains "open", based only on administrative levers.

The following main types of systems are known individual accounting heat applied to traditional vertical one-pipe heating systems.
A system with allocators (heatcostallocator - distributor of the cost of consumed heat) on each heater registers the temperature difference (tall) between the surface of the heater and the air in the room. The coolant consumption is recorded on the house meter and is used only in the calculation of the house heat consumption.

A system with coolant temperature sensors installed in the riser on each floor registers the temperature difference (te) of the coolant in the riser within each floor. The coolant flow rate is recorded at each riser and in the house heat meter.

For vertical two-pipe heating systems, only a system with allocators is used.

Both of the above systems are distributive, the principle of their operation is described in detail in the literature.

In this article, only one aspect is considered - the accuracy of the calculation of heat consumption. This information should allow the designer to make a choice between systems that is adequate to the tasks of energy saving and protecting the rights of the tenant to a fair payment for the consumed heat.

The table shows changes in temperature differences tall and test and the corresponding measurement errors in the individual metering systems under consideration, depending on the number of storeys of the building and the temperature of the coolant during heating season. In this case, the error in determining test is calculated taking into account the measurement error of the temperature sensor tdat = 0.05 °C.

Tab. 1. Temperature differences tall and test and the corresponding measurement errors

During the operation of the system, due to a number of reasons, it is possible to reduce the measurement accuracy of the sensor. For illustration, the table in brackets shows the data calculated for tdat = 0.1 °C for the variant with the largest error.

As can be seen from the table, tall >> tet, while the absolute values ​​of tet are very small. Both of these circumstances significantly affect the accuracy of the calculation of payments. So, with an average monthly charge for consumed heat, for example, 2,000 rubles. unreasonable overpayment or underpayment of individual tenants can amount to:
- 450-550 rubles / month - for a system with sensors on risers at tdat = 0.05 °С;
- 650-1,050 rubles/month - for a system with sensors on risers at tdat = 0.1 °С;
- 60-100 rubles/month — for the accounting system with allocators.

As can be seen from the example, the error in calculating payments for a system with sensors on risers is several times higher than the error in a system with allocators. Obviously, the accrual error is possible in both directions - both in favor of the tenant and in favor of the resource provider. In both cases, it is impossible to bring the balance according to the readings of the apartment and house meters, as well as to exclude complaints from the tenants or the heat supplier, up to litigation.

In any case, in the commercial calculation for heat, an individual metering system with the smallest possible error should be recommended for use.

Conclusion

The above measures for the modernization of existing vertical one-pipe and two-pipe heating systems show that in order to significantly increase their energy efficiency, there is no need to radically reconstruct traditional systems in the course of modernization, it is enough just to equip them with appropriate equipment.

Literature
1. Baibakov S. A., Filatov K. V. “On the possibility of regulating the elevator units of heating systems”. // "News of heat supply". No. 7, 2010
2. Bogoslovsky V. N., Skanavi A. N. “Heating”. - M .: Stroyizdat, 1991
3. Mileikovsky V. A. “Mathematical modeling of variable hydraulic and thermal modes of instrument assemblies of single-pipe vertical heating systems”. // Danfoss Info. No. 1-2, 2012
4. ABOK standard “Cost allocators of consumed heat from room heaters”. STO NP "ABOK" 4.3-2007 (EN 834:1994).

To date, the potential for the development of traditional heat supply systems in terms of increasing heat transfer without significant material costs is almost exhausted. In them, the maximum efficiency is quite fully chosen through the use of modern heat-using equipment, electronic means regulation and control of consumption and distribution of thermal energy and heat carrier. Replacement of shell-and-tube water heaters with lamellar ones was a significant step towards increasing the turbulence of the coolant flow, and, consequently, increasing heat transfer. On the one hand, this made it possible to increase the heat transfer coefficient within 10%, and on the other hand, the tendency to overgrowing, the formation of scale, sludge and other deposits increased, which eventually leads to a decrease in the heat transfer coefficient and increased costs for transporting the coolant. A survey of management companies in the region showed that flushing of heat supply systems with lamellar hot water heat exchangers up to 200 thousand rubles are spent annually. And in budgetary organizations, due to improper operation due to further unsuitability, heat exchangers are replaced with new ones without even having worked out the regulated resource.

One of the cardinal ways to solve this problem is to transfer the coolant circulation in the heat supply system from a stationary mode to a pulsed one. In this case, several effects can be used. Firstly, the heat transfer coefficient increases (from 10 to 150%) of the moving flow, depending on the frequency and amplitude of the pulsations of the velocity of its expiration, secondly, self-cleaning of the heat transfer surfaces of the equipment is realized, and thirdly, it becomes possible to use the impulse of the momentum of the coolant, for example, to transform a part of the available pressure of the heating coolant into a heated pressure in case of independent connection of heating installations or for water circulation in the hot water supply system.

Conducted experimental studies showed that the use of pulsed coolant supply technology will guarantee to obtain:

1. decline specific consumption fuel at the heat source due to the most improved heat removal by 5 - 30%;
2. Increasing the service life of heat-using equipment heating point not less than 2 times;
3. Reduced requirements for the quality of network water;
4. Reduction of heat transfer surfaces of heat-using equipment due to an increase in the heat transfer coefficient in pulsating mode by 1.3 - 2 or more times;
5. Reducing material costs for the design and installation of a heating point and a heat supply system as a whole by reducing its total metal consumption.
6. Reducing the cost of transporting the coolant and thermal energy in the heat consumption system when the available pressure of the high-temperature coolant of the heating network is transformed into the pressure of the low-temperature coolant of the heat consumption system.
7. Relative ease of implementation of the pulsating mode.

The ability to create a significant (10 atm or more) available pressure, which is necessary for high-rise buildings, without the use of booster pumps.

As a result of the project implementation, it is expected to increase the energy efficiency of heat and power equipment of heat supply systems by at least 1.5 times in the traditional heat supply system and by more than 2.5 times when using new heat and power devices adapted to the pulsed method of supplying heat carrier.

C. Deineko

Weather-dependent regulation for heat points of centralized heating systems centralized systems heating of buildings was carried out at CHPPs, boiler houses and elevator units of central (CTP) and individual (ITP) heating points of buildings. However, due to the large length of the pipelines and the associated inertia of the systems, this did not give a real effect. At the same time, in the TsTP or ITP, elevator nodes, which did not allow quantitative regulation of the coolant. Accordingly, the temperature of the water entering the heating system varied depending on the temperature of the coolant coming from the CHP or boiler house, while the flow rate remained constant. Modern controllers make it possible to carry out qualitative and quantitative regulation of heating systems, and thus save a significant part of energy resources. Consider typical schemes for the use of controllers offered by Honeywell

Modern controllers allow you to control several circuits, each of which can be modified by changing the settings. Consider several schemes for automating the operation of a heat point using weather-dependent regulation.

The scheme of independent connection of the heating system (Fig. 1) allows not only to separate the circuits of the internal heating system from the circuit of the central heating network, to regulate the temperature of the return flow of the primary side (the temperature of the coolant supplied after the heat exchanger to the heat source), but also to carry out weather-dependent temperature control of the internal system heating (secondary side). At the same time, the temperature of the heat carrier in the heating system of the building changes depending on the selected temperature graph and fluctuations in the outside air temperature.

Rice. 1. Scheme of independent connection of the heating system:
SDC7-21N - controller; AF - outdoor air temperature sensor; VFB, WF - coolant temperature sensors; V1 - two-way control valve; DKP - circulation pump of the heating system; SDW - indoor temperature sensor or room unit for remote control

The heating medium temperature is controlled by a two-way control valve (V1), (the valve can also be installed on the supply line T1), and circulation is carried out by the operation of the heating system circulation pump (DKP). The valve regulates the amount of heat carrier entering the heat exchanger for heating water circulating in the internal heating system, depending on the readings of the heat carrier temperature sensors (WF and VFB). Depending on the outdoor temperature (AF) and the selected temperature curve, the temperature of the heat carrier circulating in the internal heating system (secondary circuit) changes. Among the possible settings for the individual heating characteristics of the system is the choice of the type of task depending on the enclosing structures, the features of the internal heating system, temporary operating modes depending on the time of day and day of the week, the antifreeze function, and the periodic switching on of the circulation pump in summer.

Air temperature control in heated rooms is carried out by using an indoor air temperature sensor or a room unit (SDW), which can be used as a remote control panel.

Malfunctions in the system are displayed on the controller display. This is, for example, a break in the sensor or a situation where it is impossible to reach the set temperature of the coolant. When using a scheme with one circuit of the heating system and one circuit DHW systems(Fig. 2), it is possible to achieve weather-compensated control of the return flow temperature of the primary side and control of the heating circuit depending on the outdoor temperature, as well as maintaining a fixed temperature value in the DHW system.

Rice. 2. Scheme of independent connection of the heating system and the DHW system:
MVC80 - controller; AF - outdoor air temperature sensor; VFB1, VFB2, VF1, SF - coolant temperature sensors; V1, V2 - two-way control valves; P1 - circulation pumps of the heating system; P2 - circulation pumps of the DHW system; PF - make-up pump of the heating system; SV1 - make-up valve of the heating system; PS1 - pressure switch

The control is carried out by means of control valves (V1 and V2), the operation of the heating and DHW circulation pumps (P1 and P2).

Automatic make-up of the heating system is carried out by the installation, make-up pump (PF) and valve (SV1). If the secondary side minimum pressure switch (PS1) generates a non-critical alarm, the make-up valve SV1 opens and the make-up pump PF starts. Setting custom characteristics carried out similarly to the previous option.

When using a circuit with one heating circuit and a DHW circuit with a two-stage heat exchanger (Fig. 3), it is possible to achieve weather-compensated control of the primary side common return temperature and weather-compensated control of the heating circuit, as well as maintaining a fixed temperature in the DHW system. Heat cold water for sanitary needs is carried out by using heat from the coolant after the heat exchanger of the heating system, and heating the water to the required temperature and maintaining it in the DHW system - due to the operation of the second stage of heating and the control valve (V2).

Rice. 3. Control scheme of the heating and hot water system with a two-stage heat exchanger:
MVC80 - controller; AF - outdoor air temperature sensor; VFB1, VF1, SF - coolant temperature sensors; V1, V2 - two-way control valves; P1 - circulation pumps of the heating system; P2 - circulation pumps of the DHW system; PF - make-up pump of the heating system; SV1 - make-up valve of the heating system; PS1 - pressure switch

The scheme of independent connection of two heating circuits is shown in fig. 4. It is used for weather-compensated control of the return flow temperature (VFB) of the primary side via valve V1.

Rice. 4. Scheme of independent serial connection of two heating circuits:
SDC9-21N - controller; AF - outdoor air temperature sensor; VFB, WF, VF1 - coolant temperature sensors; V1 - two-way control valve; MK1 - mixing valve actuator; P1 - circulation pump of the mixing circuit of the heating system; DKP - circulation pump of the direct circuit of the heating system; RLF1 - temperature sensor of the heat carrier from the heating system; SDW - indoor air temperature sensor or room module for remote control, TKM - emergency thermostat to prevent overheating of the coolant

This scheme allows to achieve the control of the mixing circuit of the underfloor heating system and the direct circuit of the radiator heating system with weather compensation or with a constant temperature.

The control is carried out by the operation of the two-way control valve V1), the three-way mixing valve (MK1) as well as the circulation pumps (P1) of the mixing circuit and the direct heating circuit pump (DKP). The return water temperature (VFB) is controlled according to an adjustable temperature curve.

To control the temperature of the heat carrier dependent systems heating (in which network water from the heat source enters and internal system heating) a three-way mixing valve (MK1) is used (Fig. 5). Before the control valve, a differential pressure regulator is installed, and in the case when the pressure in the return network pipeline (T2) is not enough for normal hydraulic mode operation of the heating system, at the outlet of the heating system after the mixing jumper, a pressure regulator "to itself" can be installed. Also, the circulation pump of the heating system (P1) can be installed not on the supply pipe of the heating system (as shown in Fig. 5), but on the return pipe.