Numerical Investigation of the Thermal Regime of Underground Channel Heat Pipelines Under Flooding Conditions with the Use of a Conductive-Convective Heat Transfer Model

Polovnikov, V.Yu.

doi:10.1007/s10891-018-1766-3

Cited by 2 publications

(3 citation statements)

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“…a heat transfer coefficient at the soil surface of h = 11.3 W/(m 2 •K), not much lower than the values specified in [11,13,14,28], was calculated. A comparison of the soil temperature profiles simulated for this case with the base case (no-leak and leak) is shown in Figure 3a.…”

Section: Heat Convection At the Soil Surfacementioning

confidence: 93%

“…In [28], a constant value of h = 14.6 W/(m 2 •K) was taken for the heat transfer coefficient at the soil surface, including convection and radiation. Furthermore, in [11,13,14], a similar value of 15 W/(m 2 •K) was used for the heat transfer coefficient between the ground and surrounding air. In our previous work [16], the average temperature difference between the air and soil surface was measured in the period of the last three months of 2009 with ∆θ = 2 • C. The heat flux density through the soil above the DN 200 channel on the reference day (31 October 2009) was measured at q s = 22.5 W/m 2 [10].…”

Section: Heat Convection At the Soil Surfacementioning

confidence: 99%

“…A number of studies using the numerical simulation of the temperature field have been carried out to identify pipeline heat loss in a buried channel with dry [10][11][12] or wet pipeline insulation [13,14]. In this study, we used a numerical procedure that was presented in detail and validated by an experiment in our previous work [15], a leak detection methodology based on the determination of the soil temperature gradient above the channel was found to be successful.…”

Section: Introductionmentioning

confidence: 99%

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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: Heat Convection At the Soil Surfacementioning

confidence: 93%