Development of reduced order flow responsive convection heat transfer models for human body segments in multiple applications
Bolineni, Sandeep Rao; van Treeck, Christoph Alban (Thesis advisor); Cook, Malcolm (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, RWTH Aachen University, 2017
In many industrial multi-physics engineering applications, models need to capture the heat transfer effects of spatial and temporal changes in conditions around the human body. For thermal comfort assessment, convection heat transfer coefficients (hc) form part of the heat balance equation of the human body. In many non-uniform flow conditions, due to the turbulently mixed or stratified environment, convection heat transfer varies significantly on the human body segments. Thus considering a whole body heat transfer coefficient for calculating overall thermal comfort may be inappropriate. Parametric, segment-wise applicable convection heat transfer correlations are seen as an alternative in order to bridge these scales and levels in space and time. Therefore, robust reduced-order convective heat transfer models are needed for predicting heat transfer between the human body and its surroundings.The main goal of this research is to develop a reduced order model database that provides the segment-wise convective heat transfer coefficients (hc) for typical indoor flow responses in multiple applications. This is achieved by using the Computational Fluid Dynamics (CFD) methodology to model air flow and heat transfer and also further to computationally evaluate the convective heat transfer coefficients for different body segments by temperature gradient analysis. Validation of CFD approach forms an integral part of this research. Chapter 6 presents the experimentally investigated heat transfer analysis around the human body and also the comparisons with numerically reproduced data.This work presents a parametric multi-segment human manikin model which has been developed based on the prerequisites of a human thermoregulation model. Furthermore, tested the parametric model by introducing the standard literature benchmarks, such as a standing manikin and a sitting manikin. Numerical results showed excellent agreement with most commonly referenced literature values. Moreover, this work highlighted the significant role of different reference fluid temperatures for determination of hc values.This thesis highlights a parametric approach for estimating segment-wise body convection heat transfer coefficients for different postures. The methodology follows a new strategy i.e. initially, primarily relevant parameters are identified which affect the convective heat exchange. Following the sensitivity analysis of numerous Computational Fluid Dynamics (CFD) simulations with varying conditions, heat transfer coefficients correlations are developed and accordingly through regression analysis the correlations accuracy is evaluated. Finally, a database-driven approach is developed in order to make correlations accessible during simulations, for example addressing energy performance. Last but not least, two application examples demonstrate the benefit of developed reduced order model database framework, such as one from the aircraft domain and the other from the building domain.
- DOI: 10.18154/RWTH-2017-09242
- RWTH PUBLICATIONS: RWTH-2017-09242