ProsNet – a Modelica library for prosumer-based heat networks: description and validation

Prosumer-based heat networks are a new concept in district heating systems that uses the ability of prosumers to operate as either producers or consumers. This type of networks allows for utilizing distributed heat generation and renewable energy sources. A broad range of individual operating modes, heat generation technologies, and topologies determine complex thermo-hydraulic behavior of such networks. Simulations help gain insights into their properties. In this paper, a Modelica library ProsNet is presented for such simulations. It is designed to set up models of prosumer-based heat networks to investigate their dynamic and steady-state performance in a user-friendly way. Important models of the library are described in more detail. Finally, a successful validation of the developed components was performed by comparing simulation results with another software for modeling bidirectional heat networks in steady-state.

Innovations in Housing and Communal Services to Increase Real Incomes of the Russian Population

The article analyzes innovative technologies for heating residential buildings as an opportunity to solve the problems of housing and communal services in the country and a way to increase the real income of the population. The methods of statistical data analysis, the logical method, and the method of mathematical modeling are used. The problem under study is that the Russian economy has been experiencing a decline in real incomes for a long period of time. Coronavirus restrictions have exacerbated the existing trends. At the same time, a significant share of the expenses of Russians is the payment for utilities. Over the past 10 years, the cost of heating has risen by 80%. The lag of the Russian energy sector from the world indicators is due to several reasons: the low energy efficiency class of houses, significant wear and tear of heating networks, functional shortcomings of centralized heating, the lack of necessary federal and regional legislative acts, and the lack of private investment. At the same time, the centralized heating system has a number of unresolved problems related to the monopoly position of the industry: significant wear of pipelines of heat networks and heat generating equipment; limitations of the maximum temperature in the cold period; systematic exceeding of the value according to the temperature schedule in the warm period; poor quality of hot water supply in the winter period; late start of heating in the early cold; obsolete and extremely dangerous method of testing heat networks. It becomes obvious that there is a need for a radical modernization of the housing and communal sector with the introduction of fundamentally new heating systems and the development of energysaving technologies in the design, construction, and major repairs of residential buildings. The economic calculation of the use of an “Electro-converter heating system” on the example of a panel house of the 507 series showed that the annual savings in heating costs will be 79.5%. The payback period of the project is 11 years. The use of innovative systems of this type in the construction of new homes will pay off the investment much faster. The most acceptable mechanism for implementing such a project may be a public-private partnership. The use of public-private partnerships in the form of concession agreements in the construction of energy-efficient residential buildings and the introduction of innovative heating systems will create favorable conditions for the large-scale introduction of energy-saving technologies, which will have a positive impact on cost savings when paying for heating services and increase real incomes of the population.

INDICATORS THERMAL AND HYDRAULIC MODES OF DISTRIBUTION HEAT NETWORKS

The task of heat supply systems is to ensure the quality of services at a minimum cost in the production and transportation of thermal energy. Because the distribution heat networks of district and district systems are characterized by significant branching and significantly longer lengths of heat pipelines compared to the main sections of heating networks, reducing heat loss in these elements of the heating system significantly affects the overall efficiency of district heating. The amount of heat loss depends on the method of laying networks and the diameter of heat pipes, thermal insulation parameters and temperature of the coolant and the environment. Based on the formulas for determining the specific pressure losses to overcome the friction forces obtained from the generalization of these projects of central heating systems of a number of residential districts of Kharkiv, calculated dependences for determining heat losses by supply and return pipelines of the main branches of the heating network. Estimates of accuracy of use of the offered formulas are carried out. The aim of the work is to determine the specific pressure losses for the main branches of heating distribution networks on the basis of generalization of design data for heat supply systems of building groups and clarification of formulas for calculating heat losses by pipelines of central heating distribution system. Based on the generalization of projects for the heating network of residential neighborhoods in Kharkiv, a formula for calculating the specific pressure loss during water movement in the pipelines of the main branches of the heating network depending on the heat load of buildings connected to the branch. Formulas for calculation of heat losses by supply and return pipelines of the main branches of a heating network of the residential district are offered. A comparison of the accuracy of calculations using the proposed formulas with existing methods for determining heat loss in branched heat supply networks, which showed the possibility of using formulas in preliminary assessments of the thermal state of networks.

Improvement of the methodology assessment of reliability heat supply systems at the facilities of main pipelines

Источником информации о техническом состоянии трубопроводов тепловых сетей объектов магистральных нефтепроводов ПАО «Транснефть» являются результаты их обслуживания и ремонта, технического освидетельствования, гидравлических испытаний и т. д. На основании этих данных проводятся расчеты показателей надежности, по итогам анализа которых осуществляется планирование дальнейшего технического обслуживания и ремонта. Однако при оценке надежности систем теплоснабжения необходимо учитывать не только срок эксплуатации и величину амортизационного износа, но и реальное состояние в конкретных условиях функционирования. Учесть многообразие факторов, которые влияют на работоспособность трубопроводов системы теплоснабжения, и тем самым повысить точность расчетов при оценке их остаточного ресурса позволяет применение кластерного анализа в дополнение к используемой методике оценки надежности тепловых сетей. В рамках настоящей работы оценка надежности объектов АО «Связьтранснефть» с применением кластерного анализа проведена на примере равнозначных участков тепловых сетей двух узлов связи, расположенных в Краснодарском крае и Республике Саха (Якутия). Currently, information about technical condition of pipelines of heat supply systems at the facilities of the main oil pipelines of PJSC Transneft is formed based on the results of maintenance and repair, technical inspection, hydraulic tests, etc. Upon these data, calculations of reliability indicators of heat networks are carried out, based on the analysis of calculations further maintenance and repairs are planned. However, when assessing the reliability of heat supply systems, it is necessary to take into account not only the service life and the amount of depreciation wear of heat network elements, but also their real state in specific operating conditions. The use of cluster analysis in addition to the currently used method of heat network reliability assessment allows us to take into account the variety of factors that affect the operability of pipelines of the heat supply system, and thereby increase the accuracy of calculations when assessing their residual resource. Within the framework of this work, the reliability assessment of Svyaztransneft JSC facilities using cluster analysis was carried out on the example of equivalent sections of heat networks of two communication nodes located in the Krasnodar Territory and the Republic of Sakha (Yakutia).

Studying the Features of Method Choice of Heat Networks Laying Which Affect Their Energy Efficiency

Purpose of research. Most of the heating network pipelines in our country have a significant service life exceeding 25 years. Due to the use of obsolete thermal insulation materials, not a reasonable choice of heat networks installation methods which not meet modern requirements of standards and technical documentation, long-haul pipelines, during the coolant transportation around 60% of heat energy is lost. As a result, the implementation of energy saving measures and improving the energy efficiency of heating networks that do not require significant investment is currently most relevant. Methods. The paper considers one of the ways to save energy in the heat supply system by choosing the most effective method of pipelines laying. There have been performed thermal calculations, taking into account the availability of different equipment of the heat network, the same type of pipeline sections of the heat network using the same thermal insulation material for different laying methods. Results.The given paper presents the results of an analytical study of the requirements for choosing a method for laying heating network pipelines in order to systematize and summarize the data of reference and modern regulatory literature, as well as generalized results of design work and recommendations of expert organizations, which plays a significant role in choosing a construction site, as well as identifying factors that can improve the energy efficiency of heat networks. One of these factors is the choice of the most effective method of pipelines laying. Conclusion. A comprehensive review of the set of conditions (geological, climatic, structural and others) in which the projected heat network pipelines will be operating allows us to choose the most effective method of laying. Owing to that method, it is possible to reduce heat energy losses by 50-80%.