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Geothermal Energy

Science – Society – Technology

Fig. 3 | Geothermal Energy

Fig. 3

From: Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates

Fig. 3

Thermal results (a Influence of material (conductivity \({\lambda }\)), b Influence of outer borehole radius \({r_o}\), c Influence of pipe length \({L}\), d Influence of Reynolds number \({Re}_{{c}}\)) Influence of several parameters on thermal performance according to Hellström (1991) for laminar and turbulent flows a Total borehole resistance for different materials over dimensionless inner pipe radius \({c}\). b Total borehole resistance for different outer pipe radii \({r_o}\) over dimensionless inner pipe radius \({c}\). c Total borehole resistance for different probe lengths \({L}\) over dimensionless inner pipe radius \({c}\). d Total borehole resistance for a set of fixed Reynolds numbers in the circular ring \({Re}_{{c}}\) and different fixed mass flow rates (\(\dot{m}\)) over dimensionless inner pipe radius \({c}\)

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