According to the response surface methodology (RSM), a statistical analysis of laminar forced convective heat transfer behavior of the multiwalled carbon nanotube (MWCNT)-deionized water nanofluid was carried out using a horizontal circular tube under constant wall heat flux. Sodium dodecyl sulfate, cetyltrimethylammonium bromide, and gum Arabic (GA) were used as surfactants to disperse MWCNT in the deionized water in order to synthesize MWCNT-deionized water nanofluids. MWCNT-deionized water nanofluids in the presence of different surfactants and MWCNT were prepared at various weight ratios (0.5:1, 1:1, and 2:1). The properties of stability, dispersion, and wettability were then studied. According to the results, MWCNT-deionized water nanofluid in the presence of GA at a ratio of 1:1 was selected as the best sample. Nanofluids at concentrations of 0.05 and 0.1% wt% were then prepared. According to the statistical model (RSM), a total of 15 experiments were tested under the laminar flow regime and a flow rate of 171.4–545.4 ml/min, concentration of 0–0.1 wt%, and a magnetic field 0–400 G. The maximum heat transfer coefficient (1,600.1 W/m2K) was obtained at a concentration of 0.09wt%wt, a flow rate of 301.3 ml/min, and a magnetic field of 400 G. The experimental results are in agreement with the results obtained by RSM method, confirming the validity and responsiveness of the method.

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