Experimental Analysis of Thermal Performance in a Two-Phase Closed Thermosiphon Using Graphene/Water Nanofluid

Abstract

In the present study, the effect of graphene/water nanofluid on the thermal performance of a two-phase closed thermosiphon (TPCT) has been considered. For the synthesis of the mentioned nanofluids, graphene with a thickness of 4–20 nm and length of 5–10 μm has been employed. Due to the natural instability of graphene in polar solvents such as water, gum arabic (GA) has been utilized as a surfactant. Then, various nanofluids at weight concentrations of 0.02–1% were prepared and thermal properties were investigated at the input power of 30–150 W. In agreement with the results, as the weight concentration increased, the overall heat transfer coefficient and thermal efficiency of the TPCT were enhanced. On the other hand, increasing the nanofluid weight concentration and input power led to lower thermal resistance of the TPCT. Interestingly, the rate of change of the temperature in the evaporator has been studied as one of the key parameters affecting the thermal resistance and overall heat transfer coefficient of the TPCT. Increasing the concentration has compounded the reduction of the average temperature of evaporation, which has confirmed the reduction in thermal resistance. Meanwhile, the overall heat transfer coefficient increased with rising concentration at the permanent input power. Also, the vacuum pressure results showed that increasing the concentration of nanofluid led to the vacuum pressure drop being intensified.

Synthesis of ethylene glycol-treated Graphene Nanoplatelets with one-pot, microwave-assisted functionalization for use as a high performance engine coolant

“…In similar study, the thermal conductivity and heat transfer enhancements of MWCNTs-based water nanofluids were investigated and a noticeable enhancement was reported that was attributed to the thinning of the thermal boundary layer by MWCNTs and reducing the thermal resistance [28,29]. However, among various carbon-based nanostructures, graphene-family nano-materials (GFN) appears to over more potential due to their attractive thermal, electrical and mechanical properties [6,30,31]. In fact, GFN has found many applications including its use as high-performance coolant.…”

Heat transfer performance of two-phase closed thermosyphon with oxidized CNT/water nanofluids

“…In this study, experiments were performed at five input powers (30,45, 60, 90 and 120 W) and the volume flow rate was 250 mL min −1 . In order to evaluate the effects of the oxidation stage and power of acids, five CNT/water nanofluids oxidized with different acids were prepared.…”

“…Azizi et al [30] investigated the effect of graphene/ water nanofluids on the thermal efficiency and resistance of two-phase closed thermosyphon (TPCT). They concluded that as the concentration increased, the thermal efficiency of the TPCT also increased.…”

“…[6,27,28]. The results reported by Liu et al [1], Xue et al [29] and Azizi et al [30] indicated that nanofluids including nanoparticles with higher heat transfer coefficient like CNT and graphene can be more suitable in terms of heat transfer characteristics.…”

Heat Transfer Performance of a Multi-heat Pipe Using Graphene Oxide/Water Nanofluid

“…Azizi et al [3] analyzed experimentally the effect of graphene/water nanofluid on the thermal performance of a two-phase closed thermosyphon with various weight concentrations ranged from 0.02% to 1% at the input power of 30-150 W. The reported results showed that the highest thermal efficiency (90.2%) was obtained in the concentration of 1 wt.% and with input power of 120 W. Kim and Bang [4] carried out experiments to observe the effect of GO (graphene oxide)/water nanofluids (0.01 and 0.03 vol.%) on the heat pipe performance and capillary limits. A 25% reduction of the thermal resistance at the evaporator section was observed.…”