Method for Assessing Heat Loss in A District Heating Network with A Focus on the State of Insulation and Actual Demand for Useful Energy

Чичерин, Станислав; Mašatin, Vladislav; Siirde, Andres; Volkova, Anna

doi:10.3390/en13174505

Cited by 29 publications

(19 citation statements)

References 43 publications

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“…This value is similar to 17% as reported in [1]. We deal with the insulation condition, which is still considered a key parameter in methodologies for evaluating heat losses in DH networks, e.g., [2]. Minimizing losses in the DH network is also an important activity to meet the requirements of the fourth-generation district heating (4GDH) concept [3].…”

Section: Introductionsupporting

confidence: 61%

The Ability of a Soil Temperature Gradient-Based Methodology to Detect Leaks from Pipelines in Buried District Heating Channels

Perpar

Rek

2021

Energies

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We carried out several numerical experiments to analyze how different boundary conditions affect the ability to detect small pipeline leaks. Our method is based on determining the soil temperature gradient above a buried district heating channel. The equivalent thermal conductivity of a wet insulation (λeq) value of 0.5 W/(m·K) was used to mimic a small water leakage. To evaluate the heat loss through the channel cross section, the heat conduction model was used for the pipe insulation, the concrete, and the soil, while the convection model was considered within the channel. The following effects were used to simulate different operating conditions: heat convection at the soil surface, leakage only from the supply or return pipe, soil height above the channel, soil thermal conductivity, and pipe diameter. With the exception of leakage only from the return pipe and low soil thermal conductivity 0.4 W/(m·K), the results showed a doubling of the soil temperature gradient when compared with the no-leakage case. This fact undoubtedly confirms the potential of the method, which is particularly suitable for leak detection in old pipelines that have priority for renovation. A key added value of this research is that the soil temperature gradient-based leak detection technique was found useful in most foreseeable DH operating situations.

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Section: Introductionsupporting

confidence: 61%

The Ability of a Soil Temperature Gradient-Based Methodology to Detect Leaks from Pipelines in Buried District Heating Channels

Perpar

Rek

2021

Energies

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“…This factor is now used to compare the new measurement set-up (fully insulated) with the previously used set-up (hat insulated). Factor F is calculated according to Equations ( 4) and (5). A factor F of 0 indicates a perfect match with the supply fluid temperature, T f , and no impact from the manhole temperature, T m .…”

Section: Results Of Field Test Measurementsmentioning

confidence: 99%

“…Through aging and degradation, the PUR foam loses its insulating capacity with time, resulting in unwanted heat losses [2]. Numerical modelling has been conducted for the assessment of heat losses in DH pipes, e.g., [3][4][5][6]. However, we lack an on-site method in field for quantifying these heat losses, which are hard to assess with high accuracy for isolated parts of a network, especially in a non-destructive manner in an operating network.…”

Section: Introductionmentioning

confidence: 99%

Diagnostic Protocol for Thermal Performance of District Heating Pipes in Operation. Part 2: Estimation of Present Thermal Conductivity in Aged Pipe Insulation

2021

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Buried and operating district heating (DH) pipes are exposed to thermal degradation of their polyurethane (PUR) insulation over time, and their status is hard to assess without excavation. By using DH pipe valves in manholes as measurement points during a shutdown with an ensuing cooling period, non-destructive assessments can be performed. This study compares new improved field measurements with numerical simulations of the temperature decline in drainage valves and shutdown valves. The drainage valve measurements were used to thermally assess part of a buried DH network. Results indicate that by using the drainage valves as measurement points in a cooling method, the thermal conductivity of the buried DH network could be predicted with an accuracy of >95%. In addition, a general diagnostic protocol has been established for assessing the thermal status of a DH network, ready for network owners to use.

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“…These issues play an important role in social, technical, and political terms. These aspects are related also with heat losses in the buildings and district heating systems, which was also underlined in the work [15]. The analysis of sensitivity of energy distribution for residential buildings is presented in the paper [16].…”

Section: Introductionmentioning

confidence: 92%

Introduction to the Dynamics of Heat Transfer in Buildings

Babiarz

Szymanski²

2020

Energies

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Changing climatic conditions cause the variability of the parameters of the building’s surroundings, which in turn causes both the gains and losses of heat to change over time. There is variability in both daily and annual cycles. Meeting the requirements of thermal comfort in rooms requires maintaining the required parameters, including constant temperature. Heat gains and losses must be balanced, and this balance is ensured through appropriate heating systems. At the same time, the above means that the demand for heating buildings is not constant but depends on external weather conditions and the energy efficiency of the building. This, in turn, affects the thermal inertia, causing changes in the partition temperature to occur slower than the changes in air temperature. Therefore, the amplitude of the heating power changes is not proportional to the amplitude of the outside air temperature change. The paper presents an example of the analysis of thermal dynamics in buildings. Various aspects of heat transfer in the building were investigated taking into account the transient conditions. The variability of temperature over time at different depths of the partition was analysed, showing the results graphically. The periodic variability of the outside air temperature and the intensity of solar radiation were described by the Fourier series. Moreover, the article shows the influence of the thermal insulation thickness of the external wall on the annual amplitude of temperature changes and on the duration of the heating season, which is important from the point of view of optimization.

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Method for Assessing Heat Loss in A District Heating Network with A Focus on the State of Insulation and Actual Demand for Useful Energy

Cited by 29 publications

References 43 publications

The Ability of a Soil Temperature Gradient-Based Methodology to Detect Leaks from Pipelines in Buried District Heating Channels

The Ability of a Soil Temperature Gradient-Based Methodology to Detect Leaks from Pipelines in Buried District Heating Channels

Diagnostic Protocol for Thermal Performance of District Heating Pipes in Operation. Part 2: Estimation of Present Thermal Conductivity in Aged Pipe Insulation

Introduction to the Dynamics of Heat Transfer in Buildings

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