Zoha Azizi

Bio: Zoha Azizi is an academic researcher from Islamic Azad University. The author has contributed to research in topics: Nanofluid & Mass transfer. The author has an hindex of 7, co-authored 20 publications receiving 572 citations. Previous affiliations of Zoha Azizi include Shiraz University & University of Tehran.

Dimethyl ether: A review of technologies and production challenges

Abstract: Dimethyl ether (DME) is a well-known propellant and coolant, an alternative clean fuel for diesel engines which simultaneously is capable of achieving high performance and low emission of CO, NOx and particulates in its combustion. It can be produced from a variety of feed-stocks such as natural gas, coal or biomass; and also can be processed into valuable co-products such as hydrogen as a sustainable future energy. This review, which also can be counted as an extensive, pioneer review paper on this topic, presents recent developments in synthesis methods of dimethyl ether as an alternative energy while focuses on conventional processes and innovative technologies in reactor design and employed catalysts. In this context, synthesis methods are classified according to their use of raw material type as direct and indirect methods as well as other routes, since different methods need their own operating condition. Also, the available data for the selectivity to DME and its yield as a function of H2/CO and CO2 content of the feed is discussed.

Prediction of enhancement factor for mass transfer coefficient in regular packed liquid–liquid extraction columns

Abstract: Mass transfer coefficients are one of the most important parameters for the design of liquid–liquid extraction columns. The mass transfer coefficients of single drops in a pilot structured packed column have been measured using toluene/acetic acid/water and n-butyl acetate/acetic acid/water systems. Current research shows that theoretical models have failed to predict mass transfer coefficient precisely and are not reliable for design. In this work an empirical correlation for prediction of enhancement factor is developed. Dispersed phase mass transfer coefficients predicted by the proposed correlation are in good compatibility with experimental results. Les cœfficients de transfert de masse figurent parmi les parametres les plus importants a prendre en compte lors de la conception de colonnes d'extraction liquide-liquide. Les cœfficients de transfert de masse de chaque goutte dans une colonne a garnissage structure pilote ont ete mesures grâce a des systemes a base de toluene/d'acide acetique/d'eau et d'acetate de n-butyle/d'acide acetique/et d'eau. La comparaison entre les modeles theoriques et les resultats experimentaux de cœfficients de transfert de masse a montre que ces modeles ne sont pas assez precis pour etre appliques a la conception. Dans cette recherche, les facteurs d'accentuation du cœfficient de diffusion ont ete determines experimentalement et une correlation empirique a ete atteinte pour le facteur d'accentuation. Les cœfficients de transfert de masse de la phase dispersee qui avait ete prevus grâce a la correlation proposee s'harmonisent bien aux resultats des experiences. © 2010 Canadian Society for Chemical Engineering

Optimization of the thermal performance of nano-encapsulated phase change material slurry in double pipe heat exchanger: Design of experiments using response surface methodology (RSM)

Abstract: The immersion of nano-encapsulated phase change material (NPCM) in a carrier fluid to form NPCM slurry can ensure of the latent heat absorption and effective heat transfer. Here, the convective heat transfer of the NPCM slurry stream in a double-pipe heat exchanger were studied experimentally. PCM nanocapsules have been prepared via a mini-emulsion polymerization process. The nanocapsules consisting of n-dodecanol as the core, and polymethyl methacrylate (PMMA) as the shell were modified by graphene oxide (GO) nanosheets as an additional protective layer. Morphology as well as thermal and structural features of nanocapsules were examined and analyzed. The least particle size corresponded with a latent heat of 148.5 J/g. The enhancement mechanism of the convective heat transfer of NPCM slurry was studied via the response surface method. The heat transfer features were evaluated based on experiments designed statistically to determine the optimal values of inlet temperature (Tin), NPCM concentration (ϕ), and Reynolds number (Re). The optimization was performed aiming at the maximum enhancement of thermal efficiency (η). The validity of the developed regression models was assessed using the ANOVA technique. It is found that in the turbulent tubular flow of NPCM slurry, the inlet temperature and the mass fraction of nanocapsules have the most significant effects on the heat transfer performance. The optimum values of ϕ, Tin and Rein were found to be 14%, 83 °C and 5046, respectively, resulted in the maximum η of 4.5.

Recent advances in application of nanofluids in heat transfer devices: A critical review

Abstract: This paper presents a critical review of heat transfer applications of nanofluids. The effects of nanoparticle concentration, size, shape, and nanofluid flow rate on Nusselt number, heat transfer coefficient, thermal conductivity, thermal resistance, friction factor and pressure drop from numerous studies reported recently are presented. Effects of various geometric parameters on heat transfer enhancement of system using nanofluids have also been reviewed. Heat transfer devices covered in this paper include radiators, circular tube heat exchangers, plate heat exchangers, shell and tube heat exchangers and heat sinks. Various correlations used for experimental validation or developed in reviewed studies are also compiled, compared and analyzed. The pros and cons associated to the applications of nanofluids in heat transfer devices are presented in details to determine the future direction of research in this arena.

Power-to-liquid via synthesis of methanol, DME or Fischer–Tropsch-fuels: a review

Abstract: The conversion of H2 and CO2 to liquid fuels via Power-to-Liquid (PtL) processes is gaining attention. With their higher energy densities compared to gases, the use of synthetic liquid fuels is particularly interesting in hard-to-abate sectors for which decarbonisation is difficult. However, PtL poses new challenges for the synthesis: away from syngas-based, continuously run, large-scale plants towards more flexible, small-scale concepts with direct CO2-utilisation. This review provides an overview of state of the art synthesis technologies as well as current developments and pilot plants for the most prominent PtL routes for methanol, DME and Fischer–Tropsch-fuels. It should serve as a benchmark for future concepts, guide researchers in their process development and allow a technological evaluation of alternative reactor designs. In the case of power-to-methanol and power-to-FT-fuels, several pilot plants have been realised and the first commercial scale plants are planned or already in operation. In comparison power-to-DME is much less investigated and in an earlier stage of development. For methanol the direct CO2 hydrogenation offers advantages through less by-product formation and lower heat development. However, increased water formation and lower equilibrium conversion necessitate new catalysts and reactor designs. While DME synthesis offers benefits with regards to energy efficiency, operational experience from laboratory tests and pilot plants is still missing. Furthermore, four major process routes for power-to-DME are possible, requiring additional research to determine the optimal concept. In the case of Fischer–Tropsch synthesis, catalysts for direct CO2 utilisation are still in an early stage. Consequently, today's Fischer–Tropsch-based PtL requires a shift to syngas, benefiting from advances in co-electrolysis and reverse water-gas shift reactor design.