Enhancement of pool-boiling heat transfer using nanostructured surfaces on aluminum and copper (original) (raw)
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Energies
Pool boiling is an effective heat transfer process in a wide range of applications related to energy conversion, including power generation, solar collectors, cooling systems, refrigeration and air conditioning. By considering the broad range of applications, any improvement in higher heat-removal yield can ameliorate the ultimate heat usage and delay or even avoid the occurrence of system failures, thus leading to remarkable economic, environmental and energy efficiency outcomes. A century of research on ameliorating critical heat flux (CHF) has focused on altering the boiling surface characteristics, such as its nucleation site density, wettability, wickability and heat transfer area, by many innovative techniques. Due to the remarkable interest of using nanoparticle deposition on boiling surfaces, this review is targeted towards investigating whether or not metal oxide nanoparticles can modify surface characteristics to enhance the CHF. The influence of nanoparticle material, the...
Pool Boiling Experiments on a Nano-Structured Surface
IEEE Transactions on Components and Packaging Technologies, 2009
The effect of nano-structured surfaces on pool boiling was investigated. Saturated and subcooled pool boiling experiments were performed on a horizontal heater surface coated with vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were synthesized using the chemical vapor deposition (CVD) process. In this paper, MWCNT forests of two distinctly different heights (Type A: 9-m height, and Type B: 25-m height) were synthesized separately on silicon wafers. PF-5060 was used as the test liquid. The results show that Type-B MWCNTs yield distinctly higher heat fluxes under subcooled and saturated conditions for both nucleate and film boiling. Type-A MWCNTs provide similar enhancement in nucleate boiling (as Type-B) for both saturated and subcooled conditions. Type-B MWCNTs enhanced critical heat flux (CHF) by 40%. Increasing the height of the MWCNTs is also found to extend the wall super heat required for CHF. In contrast, Type-A MWCNTs provide only marginal enhancement in film boiling compared to bare silicon wafer, for both saturated and subcooled film boiling. Type-B MWCNTs enhanced the heat flux in the film boiling regime for the Leidenfrost point by 175% (compared to bare silicon wafer).
Thermal Science, 2015
The main focus of the present work is to characterize the ZnO nanoparticles further to prepare the ZnO nanofluid with base fluid as deionised water and to investigate enhancement in critical heat flux at different weight concentrations of nanofluids. The size of nanoparticles is found to be 55.25 nm. To study critical heat flux enhancement using ZnO nanofluid, different weight concentration of nanofluid are prepared. It is observed that maximum enhancement is 47.16% for 1.5 wt.% of ZnO nanofluid. Surface roughness and scanning electron microscopy of heater surface is carried out for all weight concentrations of nanofluid, which shows increase in Ra value up to some extent then it decreases and porosity on the surface of heater observed in scanning electron microscopy, is the source to enhance critical heat flux.
Determination Of Critical Heat Flux In Pool Boiling Using ZnO Nanofluids
2013
CHF creates inconvenient compromises between economy and safety in most industries, related to thermal systems such as nuclear power plants. In this study, pool boiling experiments were performed with water based nanofluid with Zinc Oxide nano particles from various concentration of 0.01 volume percent (%v) to 0.0001volume percent (v%) on an electrically heated Ni-Cr wire of 0.4 mm diameter at atmospheric pressure. The results showed that the water-based nano-fluids significantly enhanced CHF compared to that of pure water. The CHF values of the ZnO nano fluids were enhanced from approximately 70% to 80% of pure water. During the test it is found that, a sizable layer of nano particle deposits formed on heater surface. The CHF enhancement using deposition of nano particles are related to surface wettability of the heating surface during pool boiling. It is supposed that CHF enhancement in pool boiling of nano-fluids is mainly caused by the nanoparticles coating of the heating surface.
IJERT-Determination Of Critical Heat Flux In Pool Boiling Using ZnO Nanofluids
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/determination-of-critical-heat-flux-in-pool-boiling-using-zno-nanofluids https://www.ijert.org/research/determination-of-critical-heat-flux-in-pool-boiling-using-zno-nanofluids-IJERTV2IS70752.pdf CHF creates inconvenient compromises between economy and safety in most industries, related to thermal systems such as nuclear power plants. In this study, pool boiling experiments were performed with water based nanofluid with Zinc Oxide nano particles from various concentration of 0.01 volume percent (%v) to 0.0001volume percent (v%) on an electrically heated Ni-Cr wire of 0.4 mm diameter at atmospheric pressure. The results showed that the water-based nano-fluids significantly enhanced CHF compared to that of pure water. The CHF values of the ZnO nano fluids were enhanced from approximately 70% to 80% of pure water. During the test it is found that, a sizable layer of nano particle deposits formed on heater surface. The CHF enhancement using deposition of nano particles are related to surface wettability of the heating surface during pool boiling. It is supposed that CHF enhancement in pool boiling of nano-fluids is mainly caused by the nanoparticles coating of the heating surface.
Experimental Heat Transfer, 2018
Pool boiling heat transfer performances of Cu-Al 2 O 3-coated copper surfaces have been studied experimentally for its potential use in heat transfer applications. In the present study, a two-step electrochemical deposition method is examined. This method provides an easy control on surface properties such as porosity and coating thickness. The deposition method is studied carefully and responsible surface morphology parameters are reported. After performing the pool boiling experiments on coated surfaces with DI water, the maximum critical heat flux of 1800 kW/m 2 and heat transfer coefficient of 193 kW/m 2 K, which are 68% and 260% higher than that of bare surface, respectively.
Boiling and quenching heat transfer advancement by nanoscale surface modification
Scientific reports, 2017
All power production, refrigeration, and advanced electronic systems depend on efficient heat transfer mechanisms for achieving high power density and best system efficiency. Breakthrough advancement in boiling and quenching phase-change heat transfer processes by nanoscale surface texturing can lead to higher energy transfer efficiencies, substantial energy savings, and global reduction in greenhouse gas emissions. This paper reports breakthrough advancements on both fronts of boiling and quenching. The critical heat flux (CHF) in boiling and the Leidenfrost point temperature (LPT) in quenching are the bottlenecks to the heat transfer advancements. As compared to a conventional aluminum surface, the current research reports a substantial enhancement of the CHF by 112% and an increase of the LPT by 40 K using an aluminum surface with anodized aluminum oxide (AAO) nanoporous texture finish. These heat transfer enhancements imply that the power density would increase by more than 100%...
International Communications in Heat and Mass Transfer, 2013
This study aims to experimentally investigate the pool boiling heat transfer coefficient behavior using tungsten oxide-based deionized water nanofluids and comparing them to deionized water as conventional fluid. The influence of different dilute volumetric concentrations (0.005%-0.05% Vol.) and applied heat fluxes were examined to see the effect of these parameters on the pool boiling heat transfer performance using nanofluids from a typical horizontal heated copper tube at atmospheric pressure conditions. Results demonstrated that the pool boiling heat transfer coefficient (PBHTC) for both deionized water and nanofluids increased with increasing the applied heat flux. The higher PBHTC enhancement ratio was 6.7% for a volume concentration of 0.01% Vol. at a low heat flux compared to the deionized water case. Moreover, the PBHTC for nanofluids was degraded compared to the deionized water case, and the maximum reduction ratio was about 15% for a volume concentration of 0.05% Vol. relative to the baseline case. The reduction in PBHTC was attributed to the deposition of tungsten oxide nanoflakes on the heating surface during the boiling process, which led to a decrease in the density of the nucleation sites.
Journal of physics, 2019
The present paper is based on experimental studies on nucleate pool boiling heat transfer enhancement of different surfaces using water as a base fluid at atmospheric pressure. The test surfaces for the experiments include untreated, treated, and treated with Aluminumsilver oxide composite thin film surfaces having nano-layer thickness of 180 nm and 260 nm. The thin films are prepared on copper substrate by electron beam evaporation technique. The characterization of the heated surfaces is done by using optical surface profilometer for surface roughness and sessile drop method for contact angle measurement. The experiment is conducted in a closed boiling chamber and the heat flux is varied from 141.524-1244.101 kW/m 2 in time steps. The enhancement of heat transfer coefficient is found as 22.8%, 17.27% and 11.81% from the 260 nm, 180 nm composite nanostructured coated and treated surfaces respectively compared to plain surface. Enhancement in nanostructured coated surfaces is found higher due to the capillary effect, increased wettability and high active nucleate site density and the increased rate of bubble frequency.
Journal of Physics: Conference Series, 2019
The present paper is based on experimental studies of augmentation of pool boiling heat transfer characteristics of unlike surfaces using water as a working fluid at atmospheric pressure. The test surfaces for the experiments include untreated, treated, copper oxide (CuO) thin film coated copper heating surfaces having coating thickness of 200 nm and 400 nm. The thin film coating is fabricated by sol-gel spin coating technique. The characterization of surfaces is done by considering wettability, surface roughness and topography study by the sessile droplet method, optical surface profile meter and X-ray diffraction [XRD]. The experiment is conducted in a closed boiling chamber and heat flux varied from 526.3 kW/m2 to 2546.689 kW/m2. The augmentation of heat transfer coefficients is found more than 40.60% of the higher thickness of copper oxide thin film coated copper heating surfaces. This is happened due to enhanced wettability, roughness and increase in active nucleation site dens...