Geothermal Energy

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Table 5 Approximation of hydraulic results following the scheme \({c_{\text{opt}}}({\text{SDR}})= \frac{m}{{\text{SDR}}} +b\)

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

Case		Parameters regression
Material	\({r_a}\)	Slope m	intercept b	RMSE
		Laminar
–	–	0.5604	0.5367	0.0011
		Turbulent
Plastic	\(r_{\min}\)	0.5996	0.6093	0.0010
	\(r_{m}\)	0.5994	0.6093	0.0010
	\(r_{\max}\)	0.5992	0.6093	0.0010
Steel	\(r_{\min}\)	0.6068	0.6105	0.0009
	\(r_{m}\)	0.6081	0.6118	0.0009
	\(r_{\max}\)	0.6099	0.6126	0.0010
Stand.	\(r_{\min}\)	0.5954	0.5639	0.0011
	\(r_{m}\)	0.5935	0.5770	0.0010
	\(r_{\max}\)	0.5927	0.5940	0.0010
Switch	\(r_{\min}\)	0.5959	0.6293	0.0009
	\(r_{m}\)	0.5997	0.6274	0.0009
	\(r_{\max}\)	0.6074	0.6226	0.0009
		Turbulent rough regime
Plastic	\(r_{\min}\)	0.6092	0.6191	0.0009
	\(r_{m}\)	0.6092	0.6193	0.0009
	\(r_{\max}\)	0.6092	0.6198	0.0009
Steel	\(r_{\min}\)	0.6064	0.6109	0.0009
	\(r_{m}\)	0.6073	0.6126	0.0009
	\(r_{\max}\)	0.6082	0.6147	0.0009
Stand.	\(r_{\min}\)	0.6407	0.5238	0.0013
	\(r_{m}\)	0.6414	0.5321	0.0013
	\(r_{\max}\)	0.6412	0.5438	0.0012
Switch	\(r_{\min}\)	0.5933	0.6306	0.0009
	\(r_{m}\)	0.5950	0.6298	0.0009
	\(r_{\max}\)	0.5973	0.6288	0.0009

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