Thermal regimes and thermal losses of underground pipelines in real heat exchange on the outer interaction boundary

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3 Citations (Scopus)

Abstract

The relevance of the research is caused by the need to develop new approaches to the study of thermal regimes and thermal losses of underground pipelines and it is confirmed by the main provisions of the Energy Strategy of Russia for the period up to 2030. Underground pipelines are widely used for transportation of liquids in various areas, for example, water supply and heat supply, oil pipelines and gas pipelines, technological pipelines of industrial enterprises. When designing an underground piping system, it is necessary to take into account heat exchange between the ground and the underground pipeline. In many cases this impacts significantly the economics of transportation of energy carriers. The main aim of the research is a numerical analysis of thermal conditions and heat losses of underground channel-free pipelines in real heat exchange on the outer interaction boundary and investigation of temperature fields and patterns of heat transfer in the areas of placement of underground non-channel pipelines. Objects of the research are the typical for energy transportation system underground two-pipe ductless pipelines laid in sandy and clay soils. Pipelines are insulated with polyurethane foam and protective covering waterproofing layer made of polyethylene. Temperature of energy carriers is equal to the average annual temperature of the energy carriers in the supply and return pipelines of the water heating networks during their operation according to the temperature schedule 95/70 °C. The ambient temperature is equal to the average air temperature for the heating period in the city of Tomsk. The average heat transfer coefficient at the ground-to-environment interface varied from 5 to 30 W/(m2-K). Methods: numerical solution of heat transfer problems by the finite element method using the Galerkin approximation, non-uniform finite element mesh, the number of elements of mesh is chosen from the conditions of convergence of the solution; the grid is thickened by the Delaunay method. Results: The authors have determined the magnitude of heat losses and the patterns of heat transfer in the zones of placement of underground non-channel pipelines in real heat exchange on the outer interaction boundary (change in soil temperature in depth). It was revealed that thermal conditions of underground non-channel pipelines, taking into account and without taking into account changes in soil temperature with respect to depth, differ significantly from each other. This circumstance can effect considerably in those cases where, for example, adjacent communications or engineering facilities are located in the zone of thermal influence of underground pipelines. The paper demonstrates the possibility of calculating thermal losses of underground non-channel pipelines using a model and methodology that do not take into account the change in heat exchange conditions on the outer interaction boundary.

Original languageEnglish
Pages (from-to)124-131
Number of pages8
JournalBulletin of the Tomsk Polytechnic University, Geo Assets Engineering
Volume329
Issue number1
Publication statusPublished - 1 Jan 2018

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thermal regime
Pipelines
heat transfer
energy
Temperature
Heat transfer
loss
Hot Temperature
temperature
Heat losses
Soils
soil temperature
waterproofing
heating
industrial enterprise
Engineering facilities
Waterproofing
oil pipeline
Heating
transportation system

Keywords

  • Heat losses
  • Heat transfer
  • Mathematical modeling
  • Thermal energy transportation system
  • Underground pipelines

ASJC Scopus subject areas

  • Materials Science (miscellaneous)
  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology
  • Waste Management and Disposal
  • Economic Geology
  • Management, Monitoring, Policy and Law

Cite this

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title = "Thermal regimes and thermal losses of underground pipelines in real heat exchange on the outer interaction boundary",
abstract = "The relevance of the research is caused by the need to develop new approaches to the study of thermal regimes and thermal losses of underground pipelines and it is confirmed by the main provisions of the Energy Strategy of Russia for the period up to 2030. Underground pipelines are widely used for transportation of liquids in various areas, for example, water supply and heat supply, oil pipelines and gas pipelines, technological pipelines of industrial enterprises. When designing an underground piping system, it is necessary to take into account heat exchange between the ground and the underground pipeline. In many cases this impacts significantly the economics of transportation of energy carriers. The main aim of the research is a numerical analysis of thermal conditions and heat losses of underground channel-free pipelines in real heat exchange on the outer interaction boundary and investigation of temperature fields and patterns of heat transfer in the areas of placement of underground non-channel pipelines. Objects of the research are the typical for energy transportation system underground two-pipe ductless pipelines laid in sandy and clay soils. Pipelines are insulated with polyurethane foam and protective covering waterproofing layer made of polyethylene. Temperature of energy carriers is equal to the average annual temperature of the energy carriers in the supply and return pipelines of the water heating networks during their operation according to the temperature schedule 95/70 °C. The ambient temperature is equal to the average air temperature for the heating period in the city of Tomsk. The average heat transfer coefficient at the ground-to-environment interface varied from 5 to 30 W/(m2-K). Methods: numerical solution of heat transfer problems by the finite element method using the Galerkin approximation, non-uniform finite element mesh, the number of elements of mesh is chosen from the conditions of convergence of the solution; the grid is thickened by the Delaunay method. Results: The authors have determined the magnitude of heat losses and the patterns of heat transfer in the zones of placement of underground non-channel pipelines in real heat exchange on the outer interaction boundary (change in soil temperature in depth). It was revealed that thermal conditions of underground non-channel pipelines, taking into account and without taking into account changes in soil temperature with respect to depth, differ significantly from each other. This circumstance can effect considerably in those cases where, for example, adjacent communications or engineering facilities are located in the zone of thermal influence of underground pipelines. The paper demonstrates the possibility of calculating thermal losses of underground non-channel pipelines using a model and methodology that do not take into account the change in heat exchange conditions on the outer interaction boundary.",
keywords = "Heat losses, Heat transfer, Mathematical modeling, Thermal energy transportation system, Underground pipelines",
author = "Polovnikov, {Viacheslav Yu}",
year = "2018",
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AB - The relevance of the research is caused by the need to develop new approaches to the study of thermal regimes and thermal losses of underground pipelines and it is confirmed by the main provisions of the Energy Strategy of Russia for the period up to 2030. Underground pipelines are widely used for transportation of liquids in various areas, for example, water supply and heat supply, oil pipelines and gas pipelines, technological pipelines of industrial enterprises. When designing an underground piping system, it is necessary to take into account heat exchange between the ground and the underground pipeline. In many cases this impacts significantly the economics of transportation of energy carriers. The main aim of the research is a numerical analysis of thermal conditions and heat losses of underground channel-free pipelines in real heat exchange on the outer interaction boundary and investigation of temperature fields and patterns of heat transfer in the areas of placement of underground non-channel pipelines. Objects of the research are the typical for energy transportation system underground two-pipe ductless pipelines laid in sandy and clay soils. Pipelines are insulated with polyurethane foam and protective covering waterproofing layer made of polyethylene. Temperature of energy carriers is equal to the average annual temperature of the energy carriers in the supply and return pipelines of the water heating networks during their operation according to the temperature schedule 95/70 °C. The ambient temperature is equal to the average air temperature for the heating period in the city of Tomsk. The average heat transfer coefficient at the ground-to-environment interface varied from 5 to 30 W/(m2-K). Methods: numerical solution of heat transfer problems by the finite element method using the Galerkin approximation, non-uniform finite element mesh, the number of elements of mesh is chosen from the conditions of convergence of the solution; the grid is thickened by the Delaunay method. Results: The authors have determined the magnitude of heat losses and the patterns of heat transfer in the zones of placement of underground non-channel pipelines in real heat exchange on the outer interaction boundary (change in soil temperature in depth). It was revealed that thermal conditions of underground non-channel pipelines, taking into account and without taking into account changes in soil temperature with respect to depth, differ significantly from each other. This circumstance can effect considerably in those cases where, for example, adjacent communications or engineering facilities are located in the zone of thermal influence of underground pipelines. The paper demonstrates the possibility of calculating thermal losses of underground non-channel pipelines using a model and methodology that do not take into account the change in heat exchange conditions on the outer interaction boundary.

KW - Heat losses

KW - Heat transfer

KW - Mathematical modeling

KW - Thermal energy transportation system

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