Thermal Conductivity Enhancement of Al2O3 Nanofluid in Ethylene Glycol and Water Mixture

AbstractThe ability of nanofluids that exhibits enhanced thermal performance is acknowledged by researchers through studies since decades ago. However, the observation of thermal properties for nanofluids in water and ethylene glycol based is not fully explored yet. Hence, this paper presents the thermal conductivity of water and ethylene glycol (EG) based Al2O3 nanofluid. The 13 nm sized Al2O3 nanoparticles were dispersed into three different volume ratio of water: EG such as 40:60, 50:50 and 60:40 using a two-step method. The measurement of thermal conductivity was performed using KD2 Pro Thermal Properties Analyzer at working temperatures of 30 to 70 ̊C for volume concentration of 0.5 to 2.0%. The results indicate that the thermal conductivity increases with the increase of nanofluid concentration and temperature. While the percentage of ethylene glycol increase, the range of thermal conductivity decreases due to ethylene glycol properties. The measurement data of the nanofluids give maximum enhancement of thermal conductivity at condition 2.0% volume concentration, temperature of 70 ̊C and for all base fluid

Experimental Investigation of Al2O3 - Water Ethylene Glycol Mixture Nanofluid Thermal Behaviour in a Single Cooling Plate for PEM Fuel Cell Application

AbstractThermal enhancement through application of nanofluid coolant in a single cooling plate of Proton Exchange Membrane (PEM) fuel cell was experimentally investigated in this paper. The study focuses on low concentration of Al2O3 dispersed in Water - Ethylene Glycol mixtures as coolant in a carbon graphite PEM fuel cell cooling plate. The study was conducted in a cooling plate size of 220mm x 300mm with 22 parallel mini channels and large fluid distributors. The mini channel dimensions are 100mm x 1mm x 5mm. A constant heat load of 100W was applied by a heater pad that represents the artificial heat load of a single cell. Al2O3 nanoparticle used was 0.1 and 0.5 vol % concentration which was then dispersed in 50:50 (water: Ethylene Glycol) mixture. The effect of different flow rates to heat transfer enhancement and fluid flow represented in Re number range of 20 to 120 was observed. Heat transfer was improved up to 13.87% for 0.5 vol % Al2O3 as compared to the base fluid. However the pressure drop also increase which result in pumping power increment up to 0.02W. The positive thermal results implied that Al2O3 nanofluid is a potential candidate for future applications in PEM fuel cell thermal management

Heat transfer augmentation of mixture ratio TiO2 to SiO2 in hybrid nanofluid / K.A. Hamid...[et al.]

The efficiency in heat transfer fluid for cooling systems can be improved with the use of hybrid nanofluid. The combination of two or more single nanoparticles in the hybrid nanofluid improve their thermo-physical properties, hence contribute in heat transfer performance. The experimental investigation on forced convection heat transfer of hybrid nanofluid have been carried out on the evaluation of heat transfer coefficient and Nusselt number. The designated working temperature was 30oC, tested for various volume percentage of TiO2 to SiO2. The experiment was conducted in a plain tube under constant heat flux at 7,955W/m2. The hybrid nanofluid was prepared at 1.0% volume concentration at three mixture ratios of TiO2 to SiO2. The range of average enhancement in the heat transfer coefficient and Nusselt number observed were 13.6-29.7% and 9.0-17.8%, respectively. The ratio of TiO2 to SiO2 at 20:80 showed the optimum ratio that can be used to obtain maximum enhancement in heat transfer coefficient and Nusselt number. The pressure drop of the hybrid nanofluid increased about double the base fluid for ratio 50:50. Due to the small increment in friction factor which was 1.03 times, the hybrid nanofluid are appropriate for application of cooling systems. It is recommended to use TiO2- SiO2 nanofluid at ratio 20:80 due to its significant enhancement in heat transfer but least increment in friction factor

Improvement of Nanofluid stability using 4-Step UV-Vis Spectral Absorbency Analysis / M.Z. Sharif...[et al.]

The most challenging matters for the utilization of nanofluid into a certain system is its stability. The nanofluid with undesirable stability will damage the system due to fouling, and settlement from the base fluid. In addition, unstable nanofluid will have a lower thermal performance enhancement. An improved method, 4-Step UV-Vis spectral absorbency analysis has been suggested to improve the stability of the nanofluid. SiO2 nanoparticles were dispersed in the PAG lubricant by using the two-step preparation method. The stabilization methods of the SiO2/PAG were done by using the suggested method. The result indicates that all nanofluid shows good stability in stationary position even after 30 days. The absorbance of every three concentration decreased compared to their respective initial absorbance, but maintained for specific value at over 70 % compared to the initial absorbance even after 30 days

A review of nanofluid adoption in polymer electrolyte membrane (pem) fuel cells as an alternative coolant

Continuous need for the optimum conversion efficiency of polymer electrolyte membrane fuel cell (PEMFC) operation has triggered varieties of advancements, namely in the thermal management engineering scope. Excellent heat dissipation is correlated with higher performance of a fuel cell, thus increasing its conversion efficiency. This study reveals the potential advancement in thermal engineering of a fuel cell cooling system with respect to nanofluid technology. Nanofluids are seen as a potential evolution of nanotechnology hybridization with the fuel cell serving as a cooling medium. The available literature on the thermophysical properties of potential nanofluids, especially on the electrical conductivity property, has been discussed. The lack of electrical conductivity data for various nanofluids in open literature was another challenge in the application of nanofluids in fuel cells. Unlike in any other thermal management system, a nanofluid in a fuel cell is dealt with using a thermoelectrically active environment. The main challenge in nanofluid adoption in fuel cells was the formulation of a suitable nanofluid coolant with heat transfer enhancement, as compared to its base fluid, but still complying with the strict limits of electrical conductivity as low as 2 mS/cm and several other restrictions discussed by the researchers. It is concluded that a nanofluid in PEMFC is advantageous in terms of both heat transfer and simplification of the cooling system through radiator size reduction and potential elimination of the deionizer as compared to the current PEMFC cooling system. However, there are challenges that need to be well addressed, especially in the electrical conductivity requiremen

Study on Different Range of NIR Sensor Measurement for Different Concentration of Glucose Solution

The development of noninvasive methods to replace the conventional finger pricking method to measure the blood glucose concentration is developing rapidly. This study was conducted to evaluate different wavelength of near infrared (NIR) sensors that is going to be the best in measuring the glucose concentration samples that was prepared. Three different wavelengths of NIR sensor are used for the testing, 800 nm, 940 nm and 950 nm. Several experiments were conducted to find the relationship between the output voltages and glucose concentration. The results of the experiments proved that the linear relationship between output voltages and glucose concentration is significant for all NIR sensors used and the NIR sensor with a wavelength of 940 nm shows the best fit

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186

Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

The inclusive transverse momentum ($p_{\rm T}$) distributions of primary charged particles are measured in the pseudo-rapidity range $|\eta|<0.8$ as a function of event centrality in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=2.76$ TeV with ALICE at the LHC. The data are presented in the $p_{\rm T}$ range $0.15<p_{\rm T}<50$ GeV/$c$ for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor $R_{\rm{AA}}$ using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-$p_{\rm T}$ particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with $R_{\rm{AA}}\approx0.13$ at $p_{\rm T}=6$-7 GeV/$c$. Above $p_{\rm T}=7$ GeV/$c$, there is a significant rise in the nuclear modification factor, which reaches $R_{\rm{AA}} \approx0.4$ for $p_{\rm T}>30$ GeV/$c$. In peripheral collisions (70-80%), the suppression is weaker with $R_{\rm{AA}} \approx 0.7$ almost independently of $p_{\rm T}$. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284

Two-pion Bose-Einstein correlations in central Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/388

Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV

Inclusive transverse momentum spectra of primary charged particles in Pb-Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross section. The measured charged particle spectra in $|\eta|<0.8$ and $0.3 < p_T < 20$ GeV/$c$ are compared to the expectation in pp collisions at the same $\sqrt{s_{\rm NN}}$, scaled by the number of underlying nucleon-nucleon collisions. The comparison is expressed in terms of the nuclear modification factor $R_{\rm AA}$. The result indicates only weak medium effects ($R_{\rm AA} \approx$ 0.7) in peripheral collisions. In central collisions, $R_{\rm AA}$ reaches a minimum of about 0.14 at $p_{\rm T}=6$-7GeV/$c$ and increases significantly at larger $p_{\rm T}$. The measured suppression of high-$p_{\rm T}$ particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb-Pb collisions at the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98