Computer-aided design of heat supply systems for individual construction

. The use of CAD in various industries in a competitive environment becomes profitable for both the designer and the customer. The subject of the study is a system of computer-aided design of systems for comfortable living on the territory of a country house, private apartment or office work. The considered system makes it possible to increase the economic efficiency of the heating system as a whole.


Introduction
Currently, the term "computer-aided design system" refers to the design process using complex machine graphics tools supported by application software packages for solving analytical, qualification, economic and ergonomic problems related to project activities on computers. CAD is used in such fields as mechanical engineering, electrical engineering, aviation, shipbuilding, automotive, construction and others [1].
The use of CAD in various industries in a competitive environment becomes profitable for both the designer and the customer. From an economic point of view, the costs of purchasing or developing and maintaining the system are compensated by the speed of project release, reducing the number of employees involved, improving quality (at least eliminates errors caused by the human factor) and compliance of documentation with current norms, rules and standards [2].
It should also be noted that modern systems tend to meet the highest level of complexity, since automation of a single part of the design process does not lead to a significant improvement in the process as a whole, and sometimes even creates additional difficulties, for example, associated with the development of specific calculation programs [3].
Automated systems allow you to solve problems that cannot be fully formalized. Design in such systems is carried out under the direct control of a human operator, most often at the level of a human-machine dialogue. A person makes a decision himself where the design process cannot be mathematically described or the evaluation of design decisions has no quantitative expression. When working with such systems, the professional level of the designer is actively used, as well as the developed expert system.
In computational and optimization systems, various calculations are initially performed on a computer, and then at a second, higher level, using the results of these calculations, the search for optimal characteristics, for example, structures, is conducted. The basis of such CAD systems are packages of control and application programs. Most often, the mode of operation is dialog, but there is also a batch mode. A graphical interpreter in such systems usually provides output of final or intermediate design solutions to graphic and text output devices. Now, on the basis of two-and three-level systems, so-called virtual divisions are beginning to function. Designers, calculators and technologists can exchange information based on remote access via the Internet, i.e. users are geographically separated and may even be located in different countries. At the same time, their work takes place with only data, so the main task of the system is to protect the design process from collisions.

Main Part
When designing systems for comfortable living on the territory of a country house, private apartment or work in an office, shopping center, special attention is paid to the purpose, efficiency and necessity of a particular system to ensure the return on investment. This becomes especially relevant in the context of the development of energy saving programs at the state level.
The main systems that ensure normal functioning are heating, ventilation, air conditioning, sewerage, hot and cold water supply, electricity supply, including lighting. However, the design of "smart home" type systems provides for such systems and functions as video surveillance, fire extinguishing, watering, window and door management (including garage doors), home entertainment, etc., which is not surprising, due to the cost of such a project, it will be available to a limited number of customers.
Energy systems for ensuring human life depend on the level of comfort of industrial, household, and administrative buildings. In turn, the latest technical achievements, the welfare of the nation, the ethnographic characteristics of the population, and ultimately, the physiological needs of a person determine the comfort of the microclimate of the premises. Currently, the comfort of the microclimate of the room is provided by heating, ventilation and air conditioning systems. The degree of comfort directly affects the increase in labour productivity and the decrease in the morbidity of workers, which affects the growth rate of national income in our country. However, the use of comfortable air conditioning and ventilation systems with an increase in the multiplicity of air exchange leads to additional energy consumption and should be justified economically.
It is known that up to 25% of the extracted fuel and energy resources are spent on heating and ventilation. Cost reduction in the operation of industrial and residential buildings, as well as communication networks is the most important task.
The thermal balance of the room is compiled separately for each period of the year separately by explicit and latent heat (figure 1).  1. The thermal balance of the room in the cold and warm period of the year:1 -heat loss through the floor, 2 -heat gain from the heater, 3 -heat loss through the windows, 4 -heat loss through the exterior walls, 5 -heat loss through the roof, 6 -heat loss due to air exchange, 7 -heat gain through the roof, 8 -heat gain through the walls, 9heat gain from solar radiation through the windows.
The thermal balance of buildings and structures allows you to establish a relationship between heat losses and the amount of heat generated by various sources inside buildings and structures.
In general, the compilation of thermal balances allows you to determine the efficiency of the installation, the consumption of fuel or electricity to produce a unit of thermal energy, the consumption of steam (or other coolant) to produce a single product. The heat balance is a ratio linking the arrival and consumption of heat and is made up per unit of output, per 1 kg of solid or liquid fuel, per 1 m 3 of gaseous fuel or as a percentage, %, of the introduced (total) available heat.
The thermal balance of the calculation room is compiled to determine the excess or lack of heat, which should be compensated by the microclimate systems of the premises. In a room in which a constant (stationary, not changing in time) thermal regime is maintained, a thermal balance must be observed (this follows from the law of conservation of heat) [4].
Even if there were no microclimate systems in the room, that is, heating and ventilation systems, the heat balance would still be observed, just a balance would exist at indoor air temperatures unacceptable to humans. The presence of a system to ensure the microclimate of the premises allows you to ensure a thermal balance at the required indoor air temperature.
A constant thermal regime should be maintained around the clock during the entire heating period in buildings: residential, industrial with continuous operation, children's and medical institutions, hotels, sanatoriums, etc. To solve the issue of the need for the device and the power of the heating system, the values of heat loss (heat consumption) and heat gain are compared in the calculated mode (with maximum heat deficit).
Information of all components of heat loss and heat gain in the thermal balance of the room is determined by the lack or excess of heat. If the heat loss is greater than the heat release, then heating of the room is required.
Let's consider the algorithm of the system functioning. The system provides for operation in two modes; calculation and equipment selection mode, implemented in separate modules.
Getting started in the program is accompanied by user initialization. Each request is recorded in the database of visits. Next, the user has the option of choosing a module to work with.
Based on the results of the work, the user receives the final values of the parameters and an automatically compiled equipment specification, as well as the total amount of costs for the purchase of equipment and operation.
For inexperienced users, the program offers reference information, including a list of necessary equipment, a description of various heating systems, hot water, system diagrams and key design parameters. As a result, the user receives excerpts from the database . The user sets the initial data of the design object, depending on the choice of the object itself and the type of heating, hot water supply and heat curtain. Based on the results of the calculation, the found parameter value and the approximate cost of operating costs are displayed on the screen, for example, the calculation of the capacity of a gas boiler is accompanied by an estimate of the cost of natural gas to obtain 1 kW of power, and annual gas costs are calculated based on the current cost of m3 of gas.
The use of such a system in design organizations increases the speed of calculation of individual systems, while reducing the internal costs of the project. These additional features make it possible to increase the economic efficiency of the heating system as a whole.
The implemented additional features based on intelligent components aimed at giving advice, implementing forecasts based on situational modeling, as well as the ability to track temperature dependencies allow you to expand the functionality of the system and increase the efficiency of the system. The use of situational modeling methods will reveal the irrational layout of heaters at an early stage of circuit modeling, and the implementation of the tips will help to avoid errors in the layout and tracing.
Visualization of graphs of additional dependencies of contour parameters will allow the most complete analysis of the implemented contour, increase the economic and functional efficiency of the system, will allow analyzing problem situations.
The use of intelligent components in the design avoids a number of problems associated with the visualization of data in the calculations of the CAD module, reduces the error in calculations and increases the visibility of results, as well as provides decision support in the use of automated construction systems. The complex of the proposed intelligent components, when integrated into construction CAD systems, will allow the most accurate visualization of heat flows using the program. This will increase the accuracy of all calculations and will further affect the quality of the layout of heating elements in the contour of engineering networks.

Conclusions
The considered system of computer-aided design of heating and hot water systems for individual construction meets the tasks and requirements, is a computer-aided design system and has the following characteristics: -works with objects in the field of individual construction (cottages), private apartment-byapartment modernization of the heating system in standard houses with central heating, as well as separately constructed shops (retail halls).
-has the capabilities to design heating systems (with natural and forced circulation), hot water, both autonomous and in combination with a heating system and heat curtains; -performs qualified calculations of the necessary parameters and selection of equipment according to the specified initial data together with an assessment of operational and capital costs.