NUMERICAL ANALYSIS OF UNSTEADY HEAT TRANSFER IN UTUBE GEOTHERMAL HEAT EXCHANGER

This paper presents a numerical model for unsteady heat transfer in geothermal borehole heat exchanger. Heat transfer in the fluid circulating in the pipe is considered as one-dimensional and the governing differential equation is discretized using control volume method. Heat transfer through the pi...

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Bibliographic Details
Published in:Annals of Faculty Engineering Hunedoara 2018-05, Vol.16 (2), p.141-144
Main Authors: Tombarević, Esad, Vušanović, Igor
Format: Article
Language:English
Subjects:
Boreholes
Differential equations
Discretization
Geothermal power
Groundwater flow
Grout
Heat exchangers
Heat flux
Heat transfer
Mathematical models
Numerical analysis
Pipes
Short circuits
Thermodynamic properties
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Summary:This paper presents a numerical model for unsteady heat transfer in geothermal borehole heat exchanger. Heat transfer in the fluid circulating in the pipe is considered as one-dimensional and the governing differential equation is discretized using control volume method. Heat transfer through the pipe wall, grout, and surrounding soil is regarded as three-dimensional and the governing equation is discretized using 3D CVFEM method. The final solution is obtained by simultaneously solving the coupled systems of equations. The numerical solution is verified through comparison with analytical solutions for the cases of simplified geometry and boundary conditions. Overall numerical model is validated through comparison with available experimental results. The abilities of proposed numerical model are demonstrated through analysis of unsteady heat transfer following the step change of inlet fluid temperature where temperature profile of heat transfer fluid along the pipe as well as heat fluxes on the borehole wall and short circuit heat flux are of interest. Finally, the influence of various parameters (velocity and fluid temperature at the inlet, thermal properties of pipe, grout, and soil, shank spacing and groundwater flow) are analysed and the results are systematically presented.
ISSN:1584-2665
2601-2332