Mojtaba Aghajani Delavar

Athabasca University · Faculty of Science and Technology

Temperature and dissolved oxygen (DO) are of critical importance for sustainable aquatic ecosystem and biodiversity in the river systems. This study aims to develop a data-driven model for forecasting water quality in the Athabasca River using a seasonal autoregressive integrated moving average model (SARIMA) for forecasting monthly DO and water te...

he utilization of photofermentative processes to create biohydrogen and bioplastic has significant environmental and economic benefits. In this study, a mechanistic model of photo fermentation of acetic acid to investigate simultaneous bioplastic and biohydrogen production was developed. Two distinct bioreactors: one with a porous structure generat...

Phytoremediation is a cost-effective and environmentally sound approach, which uses plants to immobilize/stabilize, extract, decay, or lessen toxicity and contaminants. Despite successful evidence of field application, such as natural attenuations, and self-purification, the main barriers remain from a "promising" to a "commercial" approach. Theref...

In this study, a three‐dimensional coupled lattice Boltzmann model and cellular automata platform was developed to simulate biofilm growth and phenol biodegradation as an effective and sustainable way to remove phenolic contaminants in aquatic systems. Two three‐dimensional bioreactors with cubic or spherical obstacles at varying inlet phenol conce...

In hot and dry areas, evaporative cooling can enhance the performance of air-cooled condensers. Pre-cooling of a condenser airflow in a channel by a spray nozzle has been studied numerically. The Eulerian-Lagrangian 3D equations for two-phase flow have been discretized using the finite volume method. An experimental setup has been prepared to valid...

Over the past 25-30 years, there have been rapid advances in various areas of computer technologies, applications, and methods (e.g., complex programming and algorithms, lattice Boltzmann method, high-resolution visualization, and high-performance computation). These new and emerging technologies are providing unprecedented opportunities to develop...

Charge and mass transports play an important role in performance of proton-exchange membrane fuel cell. In this chapter, we discuss the modeling principles of charge and mass transports. Then we present the thermodynamic concepts of charge and mass processes with an emphasis on operating cell parameters. The charge transport and mass transport equa...

Biohydrogen is renewable and has a huge potential to replace fossil fuels. Understanding mechanisms of controlling microbial processes of the dynamic membrane is critical for effective dark fermentative biohydrogen production in a dynamic membrane bioreactor (DMBR). This paper aims to develop a sophisticated model of biofilm growth, dynamic membran...

In hot and dry climates, evaporative cooling of the air by water spray can be applied in several requirements, such as evaporative condensers which the airflow is precooled by the water spray before it reaches the condenser. The interaction between water droplets and the air is a complicated two-phase flow that is affected by the several parameters...

Land-use and land-cover change (LULCC) are of importance in natural resource management, environmental modelling and assessment, and agricultural production management. However, LULCC detection and modelling is a complex, data-driven process in the remote sensing field due to the processing of massive historical and current data, real-time interact...

Photo fermentation is an emerging approach of biohydrogen production as it is energy saving and environmentally friendly. Understanding mechanisms of controlling the bacteria growth and biohydrogen production is critical for effective improvements in energy harvest and waste treatment in photo fermentative bioreactors. In this study a comprehensive...

Biofilms are dynamic and responsive to changing environmental conditions and multicellular lifestyles. Microorganisms adapt to their environment to stay alive, and bacterial cells are self-immobilized in the extracellular polymer substances matrix. As a consequence, it is critical to examine the basic function of biofilms in understanding the emerg...

Kinetic models of biofilm growth are considered useful in designing and controlling biological processes and bioreactors due to relatively simple tools. In kinetic models, the main phenomena of biofilm growth have been considered such as mass transfer, temperature, and biochemical processes inside a hypothetical homogenous biofilm. Transformations...

Bioreactors are used to prepare a controlled environment for microorganisms' growth through desired bioreactions. They can produce products from different types of microorganisms ranging from plants to bacteria. As different operational and environmental signals affect biofilm growth, it is a complicated approach to design high-performance bioreact...

The biofilm system in a continuum model is treated as a continuum. In this approach, biomass formation and movement are captured by differential equations. The fluid flow and substrate transport are based on conservation rules of mass, energy, and momentum. Model complexity will be depending on practical requirements. In this chapter, one-dimension...

In biofilm simulation, both cellular automaton (CA) and individual-based model (IbM) do not consider the dynamic transfer of solute components and hydrodynamics. However, the survival of any particular population in a diverse biofilm system is heavily reliant on three general processes: transformations, nutrient transport, and biofilm formation and...

Continuum models have been used for simulations of biofilm growth and development. However, biofilm structures and patterns are very heterogeneous due to various environmental circumstances. Thus, discrete models have been developed to account for biofilm heterogeneity in biofilm growth and formation and the key mechanisms. In this chapter, we will...

This Special Issue of Sustainability invites innovative scientific articles addressing climate change mitigation and adaptation in sustainable agriculture, addressing the nexus of water, energy, and food, and enhancing knowledge of complex adaptive systems. #sustainable #water #food #agriculture #climatechange #sustainability #energy #speical_issue...

iofilms are a complex and heterogeneous aggregation of multiple populations of microorganisms linked together by their excretion of extracellular polymer substances (EPS). Biofilms can cause many serious problems, such as chronic infections, food contamination and equipment corrosion, although they can be useful for constructive purposes, such as i...

Nitrate removal in wastewater systems is crucially important to maintaining the quality of potable water as well as protecting vulnerable ecosystems. In this study, a denitrification model was incorporated into Lattice-Boltzmann model (LBM) to investigate denitrification efficacy of wastewater treatment in a static mixer-reactor. The model was used...

Abstract: Watersheds in cold regions provide water, food, biodiversity and ecosystem service. However, the increasing demand for water resources and climate change challenge our ability to provide clean freshwater. Particularly, watersheds in cold regions are more sensitive to changing climate due to their glaciers’ retreat and permafrost. This rev...

The efficiency of dark fermentation, as one of the most promising bioconversion technologies to produce biohydrogen , largely depends on some important parameters, such as pH, due to the sensitivity of anaerobic bacteria and biological metabolism to pH values. Understanding mechanisms of controlling the bacteria growth and dark fermentation is crit...

Solar energy is greatly recommended as a source of renewable energy in wide range of in-house applications to large power plants. Photovoltaic (PV) panels utilized for absorbing solar energy have some limitations: low efficiency, large occupied space and high dependency on environmental conditions. Panel surface temperature is one of the main condi...

In this study, a hybrid system of solar-microturbine with and without a combustion chamber, was investigated in a cold climate region (Edmonton, Canada). We developed a thermodynamic model to analyse the effects of environmental conditions on the system performance and power output during the year considering monthly changes in temperature, dayleng...

This paper aims to develop an integrated thermal lattice Boltzmann model and cellular automata to investigate the effects of different temperatures and velocities on biofilm growth in a microbioreactor. Compared with previous studies this model accounted for direct effects of transient temperature on biofilm growth and indirect effects caused by ch...

The present study assessed the reaction rate of methane carbon dioxide reforming (MCDR) in solid oxide fuel cells (SOFCs). This reaction rate was compared with the rates of the methane steam reforming (MSR), and the water-gas shift (WGS) reactions to evaluate its importance in simulating a SOFC. In addition, the effect of the system inlet parameter...

El almacenamiento de energía fría ayuda a la capacidad de enfriamiento durante la noche para su uso posterior en las horas punta. La demanda de carga de refrigeración durante los días de verano lleva a un aumento de la demanda de energía eléctrica, aumentando la carga máxima. Por lo tanto, para reducir el consumo de energía en las horas punta, se u...

In the present study, the lattice Boltzmann method (LBM) is employed to study the diffusion phenomenon in solid oxide fuel cell (SOFC) with direct internal reforming (DIR). The main focus of this work is to correlate and estimate the diffusion coefficient through dimensionless numbers, i.e., Schmidt and Prandtl. This work tries to reveal the import...

It is a well-known challenge to simulate competition and growth of multiple microorganisms in microbioreactors due to complex interactions among microorganisms, substrate, operational conditions and structure. In this paper, we developed a multispecies thermal lattice Boltzmann model with coupling Cellular Automata model to investigate competitive...

In present study, a numerical model is employed to investigate the effects of different operating parameters and channel geometry on the performance of membrane humidifier. Simulations are performed by a commercial CFD code and based on user defined functions. Three-dimensional counter-flow humidifier model for a gas-to-gas case is considered. Resu...

Boilers are one of the major energy consumers in the building. For this reason, increasing the efficiency of this device and improving its performance is an effective step in solving the problems in building energy and reducing waste energy. Due to the limited resources of fossil fuels and the increasing cost of energy in the world, manufacturers o...

Short transport paths with high surface to volume ratios in microfluidic devices have the potential to significantly increase the heat transfer. However, because of the very low Reynolds numbers reached in microchannel flows, it is difficult to achieve effective thermal mixing. Microfluidic mixing requires fast mixing of low diffusivity fluids. In...

Recent decades of industry experiences and previous researches indicate that growth in energy consumption worldwide and limiting fossil fuel reserves will not meet future energy needs. Therefore, utilizing renewable energy sources is essential. Recuperative Organic Rankine cycle is one of the best efficient method for utilizing such resources. The...

In this article, we developed a pore‐scale model of integrated lattice Boltzmann method and cellular automata to investigate competitive growth of aerobic nitrite and ammonium oxidizers in a bioreactor. The results showed that inlet nutrient concentrations have significant effects on maximum biofilm concentration, ratio of microorganisms' concentra...

There is a growing interest in sustainable energy sources for energy demand growth of power industries. To align the demand and the consumption of electrical energy, thermal energy storage appears as an efficient method. In the summer days, by using a cold storage system like ice storage, peaks of the energy usage shift to low-load hours of midnigh...

Ice storage systems are one kind of thermal (cold) storage systems which by shifting the usage from high to low load hours (midnight or morning), balances the period of consumption. In the present investigation, the solidification process is studied in an ice storage system. The considered system is the ice-on-coil type which the ice is formed arou...

In this paper, passive droplet deformation and breakup in microchannel with obstacles were investigated. The lattice Boltzmann method based on pseudo-potential method was utilized for the two-phase flow simulation in two cases, symmetric and asymmetric deformation and breakup of droplet. Validation was performed by several well-known benchmarks. Th...

A vehicle radiator is used for cooling down the hot working fluid with airflow passing over its flow passages and fins. The proper design of the radiator is very important due to space and weight limitations in automobiles. In this study, a numerical investigation has been conducted on the improvements which can be obtained by implementing differen...

Heating and cooling of a system by heat exchanger Plays an important role in various industries. Improvement of heat transfer in heat exchangers resulted in reducing the size of heat exchanger, and utilizing more compressed heat exchangers with higher efficiency. Using helical/spiral tube is a passive method for improving the performance of heat ex...

In comparison with the straight tube, in helical coils, the centrifugal force creates a pair of longitudinal vortices, and this secondary flow increases the heat transfer coefficient. In present study, the influence of two geometric parameters of double coil tube on thermal performance of a shell and double helical coil heat exchanger is evaluated....

Growing energy demand from economic output and improved standards of living will likely put added pressure on energy supplies. Storing energy allows researchers to balance the supply and demand of energy. There are three types of thermal storage energy systems including sensible heat storage, latent heat storage and thermo-chemical storage. Ice sto...

Cold thermal energy storage, as a promising way of peak-shifting, can store energy by using cheap electricity during off-peak hours and regenerate electricity during peak times to reduce energy consumption. The most common form of cold storage air conditioning technology is ice on the coil energy storage system. Most of the previous studies so far...

The growing demand for energy-saving in industries has led to numerous researches to improve the heat exchangers thermal performance in a variety of methods. The pillow plate heat exchanger (PPHE) is one of the new types of plate heat exchangers that have specific functional properties compared to conventional plate heat exchangers. The objective o...

At the present time the electrical power is a necessary requirement for industries or even for daily life. The increase in the human population has made providing the electrical energy an important challenge, thus some techniques should be utilized to minimize the electrical demand in peak-hours and shift this demands to off-peak times. Ice storage...

The rise of energy consumption in the world and the dependence of almost every activity on electric energy creates difficulties in providing people or industries with required energy in peak-hours. Thermal energy storages are devices which can be used in order to decrease the energy consumption and created a balance in the electrical power usage du...

In this paper, the effect of using different nanofluid as a coolant fluid on the thermal performance of Pillow plate heat exchanger (PPHE) is investigated. The objective of present study is using a new heat transfer enhancement method in PPHE byutilizing nanofluid instead of pure fluid as a heat transfer medium. Accordingly, heat transfer and press...

There are two primary laws including the first and second laws of thermodynamics that should be used to assess a process. Generally, only the first law of thermodynamics is investigated in numerical solutions, so it is possible to exist some numerical results that do not satisfy the second law of thermodynamics because of numerical errors. To achie...

In general, there are two main methods for improving the performance of the heat exchanger, which include active and passive methods. Passive mode, unlike active mode, does not require external power. It is possible to increase the heat transfer rate by using changes in the levels of the heat exchanger and the flow regime or with additives to the f...

Heating and cooling of a fluid system is important in many industries. Cooling and heating systems are based on heat transfer methods. Given the limited energy resources in the world, as well as the increased cost of energy use in recent years, research In the field of energy conservation, it has been accelerated to reduce it in various processes....

In this paper, the effect of using twisted tape in both inner and outer tubes of double pipe heat exchangers is numerically investigated. A twisted tape is designed to improve the heat transfer, integrated in both pipes. The thermal performance of a double pipe heat exchanger with two fluids including water and Al2O3 nanoparticles has been studied...

In this article, a 3D numerical simulation for investigating friction factor and heat transfer enhancements in case of inserting normal or perforated dual twisted tapes (TTs) in converging‐diverging tubes (CDTs) is presented. The effects of Reynolds number changing from 10,000 to 20,000 and a various number of holes (N = 0, 1, 2, and 3) in TTs, und...

Cold energy storage helps cooling capacity overnight for later usage during peak hours. Cooling load demand during summer days leads to an increase in electrical energy demand, increasing the peak load. Therefore, to reduce energy consumption during peak hours, cold energy storage systems are used. The most common form of cold storage air condition...

Energy storage systems decrease the energy consumption and can help to reduce environmental impacts. Phase Change Material (PCM) is an efficient method in thermal energy storage with high thermal density. In the present study, the charging process of a horizontal shell-and-tube PCM storage system is evaluated by 2D simulation. In order to investiga...

According to day-by-day consumption increase, energy high costs and nonrenewable energy destroying effects, clean technologies such as fuel cells lead a remarkable decline in consumption. In the present study, waste heat recovery from a hybrid system of an 1180 kW low-temperature polymer electrolyte membrane fuel cell and a vapor compression refrig...

Nowadays due to the permanent increase in energy consumption and its high cost and also nonrenewable energies' destroying effects, clean technologies such as fuel cells should be supported and used. In present study, waste heat recovery of a low temperature proton exchange membrane fuel cell is surveyed using a recuperative organic Rankine cycle. T...

Phase Change Material (PCM)

Waste Heat Recovery

Film Cooling of the Turbine Blade

امروزه با توجه به آلایندگی¬های بسیار زیاد و همچنین کمبود انرژی¬های فسیلی می¬بایست از انرژی¬های تجدید¬پذیر کمک گرفته شود. از جمله این انرژی¬ها، انرژی زمین گرمایی است که توسط مجموعه پمپ¬های حرارتی منبع زمینی صورت می¬پذیرد. مبدل حرارتی زمین گرمایی نقش بسیار مهمی در این مجموعه به منظور تأمین انرژی مورد نیاز دارد. لذا، با استفاده از روش حجم محدود و به ص...

This work studies the eff ect of channel geometries on melting process (charging) in a phase change material (PCM) cylindrical storage. In order to investigate the melting process, diff erent geometries of HTF channel cross section including circular, rectangular, elliptical, square, and diamond-like are considered. The results show that the meltin...

In this paper, heat transfer in a compact heat exchanger duct is analyzed. The Galerkin method is applied to solve the nonlinear heat transfer equation. It is then validated by the numerical method since temperature distribution graphs fitted on each other thoroughly. Heat transfer rate at different fin geometry parameters, surface emissivity and c...

In this paper, effects of flat plate obstacles and rectangular and triangular decorated bars on cooling of a hot bar were investigated experimentally and numerically. The experiments were performed in a wind tunnel with transient heat transfer through the hot bar. Results showed that in case of staggered tube banks and Reynolds range of 350–2100, h...

This work studies the effect of channel geometries on melting process (charging) in a phase change material (PCM) cylindrical storage. In order to investigate the melting process, different geometries of HTF channel cross section including circular, rectangular, elliptical, square, and diamond-like are considered. The results show that the melting...

As pollutions impose adverse effects on human health and environment, assessment of their dispersion within the urban regions can much help to control them. In urban regions, dynamics of pollutants will be affected by buildings and barriers, and to investigate the dispersion of the pollutants, these barriers must be considered. In this article, CFD...

The micromixers offer potentially good mixing performance. In this paper mixing process in a T-micromixer was investigated using a 2D Lattice Boltzmann model (LBM). The effects of porous block porosity, location and effective thermal conductivity as well as flow Reynolds number over flow pattern and heat transfer were studied. Results indicate with...

The micromixers offer potentially good mixing performance. In this paper mixing process in a T‐micromixer was investigated using a 2D Lattice Boltzmann model (LBM). The effects of porous block porosity, location and effective thermal conductivity as well as flow Reynolds number over flow pattern and heat transfer were studied. Results indicate with...

Effect of Sinusoidal (Sin), Wave and Broken obstacles followed by rectangular and triangular decorated bars on cooling of a hot bar was investigated experimentally and numerically in the present investigation. Experiments were performed in a wind tunnel in which transient heat transfer were considered on the hot bar. The obtained results revealed t...

In present paper combination of three-dimensional isothermal and two-dimensional non-isothermal Lattice Boltzmann Method have been used to simulate the motion of bubble and effect of wetting properties of the surface on bubble separation. By combining these models, three-dimensional model has been used in two-dimension for decreasing the computatio...

This paper presents a two-dimensional mathematical model to evaluate transient heat and mass transfer during hydrogen desorption in a metal hydride storage tank. Simulation has been done by the use of Lattice Boltzmann method with D2Q9 structure. This method has not been used in almost all previous studies about hydrogen desorption. A study of oper...