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

Experiments and Models of Carbon Black-based Nanofluids for Photothermal and Electrical Applications

Nanofluid er en type væske som inneholder spredte nanopartikler, som kan forbedre deres termiske og elektriske egenskaper sammenlignet med basevæsker. Dette har ført til omfattende bruksområder, som for eksempel solenergilagring. En type anvendelse av nanofluid er i direct absorption solar collectors (DASCs), der de brukes som arbeidsvæsker for å konvertere solenergi til termisk energi. I tillegg gjør deres forbedrede elektriske egenskaper dem egnet for bruk i kjølesystemer for elektriske enheter, som dielektriske materialer, i fotovoltaiske systemer, etc. Videre har nanofluid potensiale for bruk i hydrogenproduksjon via vannelektrolyse, som kan lagre solenergi som hydrogen. Grunnet dette kan det være verdifullt å undersøke ytelsen til nanofluid i ulike energiindustriapplikasjoner. Egenskapene til nanofluid påvirkes av ulike faktorer, som materialet til nanopartikler, deres størrelse og form og konsentrasjonen. Det er derfor avgjørende å måle deres optiske, elektrokjemiske og termiske egenskaper, inkludert utryddelseskoeffisient, zetapotensial og elektrisk ledningsevne. I denne studien ble en rektangulær DASC med interne baffler og rektangulære rør med tverrsnitt designet og testet. Karbon sot (CB) nanofluid ble brukt som arbeidsvæske, og en halogenlampe ble brukt til å simulere konsentrert solstråling. De fototermiske egenskapene og forbedringene av systemet ble evaluert ved å overvåke temperaturen til arbeidsvæskene ved innløpet og utløpet, samt effektiviteten til DASC. For å studere oppførselen til nanopartikler og andre viktige parametere som er vanskelige å observere under eksperimenter, for eksempel distribusjonen av temperatur og hastighetsvektorer til arbeidsvæsker, utviklet denne avhandlingen en numerisk modell for å analysere strømningsmønsteret og distribusjonen av CB-nanopartikler i DASCs ved hjelp av en volumetrisk varmeoverføringsmodell basert på Beer-Lamberts lov. Utryddelseskoeffisienten til CB-nanofluider, som ble bestemt ved å måle reduksjonen i varmefluks når lys passerte gjennom nanofluidene, var en viktig parameter i modellen. Simuleringsresultatene kan brukes til å analysere oppførselen og avleiringen av nanopartikler, samt varmeoverføring og strømningskarakteristikker av nanofluider på mikronivå. Den elektrokjemiske ytelsen til CB-nanofluider ble evaluert gjennom en eksperimentell elektrolyse av nanofluidelektrolytter. Hydrogenproduksjonsraten fra vannsplittelsesreaksjonen og effektiviteten av elektrolysen er viktige indikatorer for å bestemme forbedringen av nanofluidelektrolytter. I denne studien ble to typer nanofluidelektrolytter, natriumsulfat og natriumhydroksid, testet. En semi-empirisk korrelasjon basert på Faradays elektrolyselov og Maxwells modell for elektrisk ledningsevne ble utviklet for å evaluere effekten av CB-nanofluider. Noen forenklinger ble gjort med hensyn til konsentrasjonen av nanofluider, slik at de kunne evalueres ved hjelp av eksperimentelle resultater. Denne korrelasjonen kan brukes til å vurdere den totale hydrogenproduksjonen for alkaliske nanofluidelektrolytter ved lave konsentrasjoner. I tillegg til de nevnte studiene, ble stabilitetstester utført for å evaluere stabiliteten til forskjellige typer og konsentrasjoner av CB-nanofluider. Faktorene som bidrar til destabilisering av nanofluider ble også diskutert i denne studien.Nanofluids are a type of fluid that contains dispersed nanoparticles, which can enhance their thermal and electrical properties compared to base fluids. This has led to their widespread use in applications such as solar energy storage. One specific application of nanofluids is in direct absorption solar collectors (DASCs), where they are used as working fluids to convert solar energy into thermal energy. Additionally, their enhanced electrical properties make them suitable for use in cooling systems for electrical devices, as dielectric materials, in photovoltaic systems, etc. Furthermore, nanofluids have the potential for use in hydrogen production via water electrolysis, which can store solar energy as hydrogen. Therefore, investigating the performance of nanofluids in various energy industry applications can be valuable. The properties of nanofluids are influenced by various factors, such as the material of nanoparticles, their size and shape, and their concentration. Therefore, it is crucial to measure their optical, electrochemical, and thermal properties, including the extinction coefficient, zeta potential, and electrical conductivity. In this study, a rectangular DASC with internal baffles and rectangular cross-section pipes was designed and tested. Carbon black (CB) nanofluids were utilized as working fluids, and a halogen lamp was used to simulate the concentrated solar radiation. The photothermal properties and enhancements of the system were evaluated by monitoring the temperature of the working fluids at the inlet and outlet, as well as the DASC's efficiency. To study the behavior of nanoparticles and other important parameters that are difficult to observe during experiments, such as the distribution of temperature and velocity vectors of working fluids, this thesis developed a numerical model for analyzing the flow pattern and distribution of CB nanoparticles in DASCs using a volumetric heat transfer model based on Beer-Lambert's law. The extinction coefficient of CB nanofluids, which was determined by measuring the reduction in heat flux when light passed through the nanofluids, was an important parameter in the model. The simulation results can be used to analyze the behavior and deposition of nanoparticles, as well as the heat transfer and flow characteristics of nanofluids at a micro level. The electrochemical performance of CB nanofluids was evaluated through an experiment on electrolyte nanofluids electrolysis. The hydrogen production rate of the water split reaction and the efficiency of electrolysis are important indicators to determine the enhancement of the electrolyte nanofluids. In this study, two types of electrolyte nanofluids, sodium sulfate and sodium hydroxide, were tested. A semi-empirical correlation based on Faraday’s law of electrolysis and the Maxwell model of electrical conductivity was developed to evaluate the effect of CB nanofluids. Some simplifications were made regarding the concentration of nanofluids, making it possible to evaluate them using experimental results. This correlation can be used to assess the total hydrogen production for alkaline electrolyte nanofluids at low concentrations. In addition to the aforementioned studies, stability tests were conducted to evaluate the stability of different types and concentrations of CB nanofluids. The factors that contribute to the destabilization of nanofluids were also discussed in this study.Doktorgradsavhandlin

Two Phase Flow, Phase Change and Numerical Modeling

The heat transfer and analysis on laser beam, evaporator coils, shell-and-tube condenser, two phase flow, nanofluids, complex fluids, and on phase change are significant issues in a design of wide range of industrial processes and devices. This book includes 25 advanced and revised contributions, and it covers mainly (1) numerical modeling of heat transfer, (2) two phase flow, (3) nanofluids, and (4) phase change. The first section introduces numerical modeling of heat transfer on particles in binary gas-solid fluidization bed, solidification phenomena, thermal approaches to laser damage, and temperature and velocity distribution. The second section covers density wave instability phenomena, gas and spray-water quenching, spray cooling, wettability effect, liquid film thickness, and thermosyphon loop. The third section includes nanofluids for heat transfer, nanofluids in minichannels, potential and engineering strategies on nanofluids, and heat transfer at nanoscale. The forth section presents time-dependent melting and deformation processes of phase change material (PCM), thermal energy storage tanks using PCM, phase change in deep CO2 injector, and thermal storage device of solar hot water system. The advanced idea and information described here will be fruitful for the readers to find a sustainable solution in an industrialized society

Gas Capture Processes

This book introduces the recent technologies introduced for gases capture including CO2, CO, SO2, H2S, NOx, and H2. Various processes and theories for gas capture and removal are presented. The book provides a useful source of information for engineers and specialists, as well as for undergraduate and postgraduate students in the fields of environmental and chemical science and engineering

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018

Proceedings of the 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008

This volume contains full papers presented at the 10th International Chemical and Biological Engineering Conference - CHEMPOR 2008, held in Braga, Portugal, between September 4th and 6th, 2008.FC

Recent Development of Hybrid Renewable Energy Systems

Abstract: The use of renewable energies continues to increase. However, the energy obtained from renewable resources is variable over time. The amount of energy produced from the renewable energy sources (RES) over time depends on the meteorological conditions of the region chosen, the season, the relief, etc. So, variable power and nonguaranteed energy produced by renewable sources implies intermittence of the grid. The key lies in supply sources integrated to a hybrid system (HS)