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首页> 外文学位 >Development and Application of a Numerical Framework for Improving Building Foundation Heat Transfer Calculations.
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Development and Application of a Numerical Framework for Improving Building Foundation Heat Transfer Calculations.

机译：改进建筑物基础传热计算数值框架的开发和应用。

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摘要

Heat transfer from building foundations varies significantly in all three spatial dimensions and has important dynamic effects at all timescales, from one hour to several years. With the additional consideration of moisture transport, ground freezing, evapotranspiration, and other physical phenomena, the estimation of foundation heat transfer becomes increasingly sophisticated and computationally intensive to the point where accuracy must be compromised for reasonable computation time. The tools currently available to calculate foundation heat transfer are often either too limited in their capabilities to draw meaningful conclusions or too sophisticated to use in common practices.;This work presents Kiva, a new foundation heat transfer computational framework. Kiva provides a flexible environment for testing different numerical schemes, initialization methods, spatial and temporal discretizations, and geometric approximations. Comparisons within this framework provide insight into the balance of computation speed and accuracy relative to highly detailed reference solutions.;The accuracy and computational performance of six finite difference numerical schemes are verified against established IEA BESTEST test cases for slab-on-grade heat conduction. Of the schemes tested, the Alternating Direction Implicit (ADI) scheme demonstrates the best balance between accuracy, performance, and numerical stability.;Kiva features four approaches of initializing soil temperatures for an annual simulation. A new accelerated initialization approach is shown to significantly reduce the required years of presimulation.;Methods of approximating three-dimensional heat transfer within a representative two-dimensional context further improve computational performance. A new approximation called the boundary layer adjustment method is shown to improve accuracy over other established methods with a negligible increase in computation time. This method accounts for the reduced heat transfer from concave foundation shapes, which has not been adequately addressed to date. Within the Kiva framework, three-dimensional heat transfer that can require several days to simulate is approximated in two-dimensions in a matter of seconds while maintaining a mean absolute deviation within 3%.
机译：建筑基础的热传递在所有三个空间维度上都有很大差异，并且在从一小时到几年的所有时间范围内都具有重要的动态影响。在考虑了水分输送，地面冻结，蒸散和其他物理现象的基础上，地基传热的估算变得越来越复杂，并且计算量很大，以至于必须在合理的计算时间内牺牲精度。当前可用于计算基础传热的工具通常要么功能有限，无法得出有意义的结论，要么太复杂而无法在常规实践中使用。 Kiva提供了一个灵活的环境来测试不同的数值方案，初始化方法，空间和时间离散化以及几何近似。在此框架内进行的比较可提供相对于高度详细的参考解决方案的计算速度与精度之间的平衡的深入了解。；六种有限差分数值方案的精度和计算性能已针对已建立的IEA BESTEST板级导热试验案例进行了验证。在测试的方案中，交替方向隐式（ADI）方案显示了准确性，性能和数值稳定性之间的最佳平衡。Kiva具有四种初始化土壤温度的方法，可进行年度模拟。显示了一种新的加速初始化方法，该方法可以显着减少所需的预模拟时间。在具有代表性的二维环境中近似三维热传递的方法可进一步提高计算性能。显示了一种新的近似方法，称为边界层调整方法，该方法比其他已建立的方法提高了精度，而计算时间却可以忽略不计。该方法说明了由于凹形基础形状而导致的传热减少，至今尚未充分解决。在Kiva框架内，可能需要数天才能进行模拟的三维热传递在几秒钟内即可二维近似，同时将平均绝对偏差保持在3％以内。

著录项

  • 作者

    Kruis, Nathanael J. F.;

  • 作者单位

    University of Colorado at Boulder.;

  • 授予单位 University of Colorado at Boulder.;
  • 学科 Architectural engineering.;Mechanical engineering.;Energy.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 215 p.
  • 总页数 215
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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