morteza khalaji assadi - Academia.edu (original) (raw)

Papers by morteza khalaji assadi

International Journal of Physical Sciences, Jun 18, 2011

In this paper, the size and performance of a dehumidification tower were studied by simulating va... more In this paper, the size and performance of a dehumidification tower were studied by simulating varying operating conditions. Based on the experimental results, this study presents the performance of a packed tower absorber for a lithium chloride desiccant dehumidification system. The effects of the main variables-airflow rate, liquid desiccant flow rate, and inlet air temperature on the rate of dehumidification were reported. It was found that the influence of these variables could be assumed to be linear. A finite difference model was developed to determine the packing height of the dehumidification towers. This model was worked out in MATLAB code, which is a suitable model for measuring the optimum height of a tower. The validity of this model was compared with published experimental data and our data. Comparisons between the simulated packing height and the actual packing heights used by experimental studies illustrated that our finite difference model is acceptable. With this model, we predict the packing height for every condition, and then we constructed the dehumidifier based on the results of our finite difference model.

4th IET Clean Energy and Technology Conference (CEAT 2016), 2016

The world demand for energy is increasing every year while the fossil fuels reservoirs are limite... more The world demand for energy is increasing every year while the fossil fuels reservoirs are limited and expected to be exhausted in few decays. Therefore, utilization of renewable energy resources is inevitable. However, to develop the infrastructures for a renewable energy system for power generation, both technical and economical evaluations are a necessity. In this paper, the feasibility of a hybrid renewable power generation, including two types of solar system, a biogas generator, and a biodiesel generator along with required battery and converter for production of 5kW electrical power is studied. The system is designed for a 20year project and the HOMER Pro program is used for system evaluation. The analysis showed that the price of biodiesel and biogas were the main controlling parameters for this project.

One of the most users of energy in the construction industry is residential buildings that use th... more One of the most users of energy in the construction industry is residential buildings that use the high value of energy. Because of the high effect of construction activities on environment, serious attention should be given to sustainability concept in construction activities. There are climate factors such as temperature, humidity and pressure that have a considerable effect on the sustainability of green buildings based on energy consumption. The main goal of this paper is to achieve a sustainable green building by optimizing the energy consumption based on two significant factors which are temperature and humidity. To achieve this goal, the design of experiments (DOE) and building simulation are applied. A two-storey house in Malaysia was selected as the case study. The final result shows that to achieve the optimum value of cooling load to have a sustained design of green residential buildings all the significant factors should be placed on a low level which it means that tempe...

Carbon nanotubes have fascinating chemical and physical properties as indicated by graphite and d... more Carbon nanotubes have fascinating chemical and physical properties as indicated by graphite and diamond characteristics, and the reason is their individual atomic structure. They have acquired critical achievements in various fields such as materials, electronic devices, energy storage, separation, and sensors. Recently, antireflective coatings with self-cleaning properties attract critical consideration for their theoretical characteristics and their wide-ranging applications. In this chapter, the benefits of using CNTs as an antireflection and self-cleaning thin coating layer have been discussed to improve mechanical and electrical behavior of solar cells. Transfer-matrix method (TMM) and finite-difference time-domain (FDTD) method were studied as most suitable technique for thin films.

Combined Heat and Power (CHP) systems have increasingly drawn attention in recent years due to th... more Combined Heat and Power (CHP) systems have increasingly drawn attention in recent years due to their higher efficiency and lower Greenhouse Gas (GHG) emission. Input-output matrix modeling was considered here as one of the efficient approaches for optimizing these energy networks. In this approach, power flow and energy conversion through plant components were modeled by an overall efficiency matrix including dispatch factors and plant component efficiencies. The purpose of this paper is to propose a modification of the objective function presented in some previous studies. This procedure was performed by adding the parameters of plant component lifetime and environmental costs to the objective function. Thus, the optimization problem was formulated by minimizing the total system levelized cost instead of simply hourly energy cost. The study results revealed that producing the electricity by the trigeneration system led to achieving 1256 MWh annual electricity savings that otherwise...

This paper presents the conceptual design of a concentrating solar power plant (CSPP) using Direc... more This paper presents the conceptual design of a concentrating solar power plant (CSPP) using Direct Steam Generation method (DSG) in a parabolic trough solar field located in Universiti Teknologi Petronas, Perak, Malaysia. The conceptual design of the CSPP includes selection and sizing of solar field, power generation cycle, types of working fluids, sizing of the power block, etc.The conceptual design is based on a mathematical modeling of the CSPP. In the present solar thermal system, a turbine is integrated with 1.2 kW generators, and steam is produced by flow loop energized by solar parabolic trough concentrators. One of the most significant factors for the successful conceptual design of a CSPP is a precise determination of the transient solar radiation over the day and the season. Accordingly, in-situ measurements of the direct normal irradiance (DNI) has been carried out and used as input to the mathematical model. As a result of daily and seasonal variation of solar radiation,...

In many applications, the number of elements in the system (i.e., machines, jobs, customers) is e... more In many applications, the number of elements in the system (i.e., machines, jobs, customers) is either constant or remain fixed. This type of a system is modeled as a closed queuing system. Closed queuing systems are those in which there is no exogenous arrival to the system and no element leaves the system. In these systems, departure from one state is an arrival to the next state. Those cases in which the system is always full and any departure from the system is immediately replaced by a new arrival are also considered closed systems. This closeness of the system changes the nature of the modeling process in which the well known queuing models need to be modified accordingly. In this research, a health care center with a limited number of beds which are used at their maximum capacity is considered. In this closed queuing system, available and reserved nurses are also modeled by means of closed queuing systems. Considering the interaction of the resulting networks, the optimal lev...

Nowadays, biomass is considered as one of the main sources of energy for both developed and devel... more Nowadays, biomass is considered as one of the main sources of energy for both developed and developing countries. Biomass is one of the potential resources of renewable energy as the novel solution for consuming and depleting the fossil fuels. Utilization of biomass for bioenergy production is a beneficial alternative to meet the increasing energy demands, reduce the carbon dioxide emission, global warming and climate change. In order to deliver a competitive biomass product, it requires a robust supply chain. This paper summarized the recent literature related to optimizing the biomass supply chain in different countries. Moreover, the barriers and problems related to the palm biomass supply chain in Malaysia and review of some operational, economic and social challenges about the biomass supply chain were investigated. Finally, several recommendations are offered for future development on the relevant fields, such as cost, strategic planning, and policy implication. This study has...

IOP Conference Series: Earth and Environmental Science, May 1, 2018

In this paper, a Simulink® Thermolib Model has been established for simulation performance evalua... more In this paper, a Simulink® Thermolib Model has been established for simulation performance evaluation of Stand-alone Parabolic Trough Solar Thermal Power Plant in Universiti Teknologi PETRONAS, Malaysia. This paper proposes a design of 1.2 kW parabolic trough power plant. The model is capable to predict temperatures at any system outlet in the plant, as well as the power output produced. The conditions that are taken into account as input to the model are: local solar radiation and ambient temperatures, which have been measured during the year. Other parameters that have been input to the model are the collector's sizes, location in terms of latitude and altitude. Lastly, the results are presented in graphical manner to describe the analysed variations of various outputs of the solar fields obtained, and help to predict the performance of the plant. The developed model allows an initial evaluation of the viability and technical feasibility of any similar solar thermal power plant.

MATEC Web of Conferences, 2017

The evaluations of the performance of solar flat-plate collectors are reported in the literature.... more The evaluations of the performance of solar flat-plate collectors are reported in the literature. A computer program developed by MATLAB has been applied for modelling the performance of a solar collector under steady state laminar conditions. Results demonstrate that Cu-water nanofluid would be capable of boosting the thermal efficiency of the collector by 2.4% at 4% volume concentration in the case of using Cunanofluid instead of just water as the working fluid. It is noteworthy that, dispersing the nanoparticles into the water results in a higher pressure drop and, therefore, a higher power consumption for pumping the nanofluid within the collector. It has been estimated for the collector understudy, that the increase in the pressure drop and pumping power to be around 30%.

IEEE Transactions on Reliability, 2018

This paper proposes an algorithm for evaluating the performance of a closed-loop spare machines s... more This paper proposes an algorithm for evaluating the performance of a closed-loop spare machines supply system when the time between failures as well as the repair times is generally distributed. The closed-loop system with finite number of machines and the generic time distribution assumption well represents real-life spare machines supply systems but at the cost of higher complexity. The increased complexity prohibits the use of existing models, which evaluate the performance of closed-loop systems assuming exponentially distributed failure and repair times. The Extended Bottleneck (EBOTT) algorithm in the literature estimates the performance measures of a closed-loop system with generally distributed repair service times. However, as our analysis indicates, the EBOTT algorithm may fall into an infinite loop even in assessing the performance of a simple spare machines supply system. The Modified EBOTT algorithm presented in this paper overcomes the shortcomings of the EBOTT algorithm and exhibits superior performance. Finally, through tradeoff analysis between spare machines inventory level and repair shop capacities, insights into the performance of such systems are presented. Index Terms-Closed-loop queuing systems, failure and repair times, general time distributions, Modified Extended Bottleneck (MEBOTT) algorithm, performance evaluation, spare machines supply system. NOMENCLATURE i Index of the node. MNP i Mean number of parts (machines) in node i. TH i Throughput of the node i. K Total number of parts (machines) in the system. F i Function for the relationship between the MNP i and the TH i for node i. e i Effective arrival ratios of the node i. err Error threshold value used to check the stopping condition of algorithms. U i Utilization of node i.

AIP Conference Proceedings, 2018

Multi tray solar dryer is commonly used for thin layers drying type due to its ease of manufactur... more Multi tray solar dryer is commonly used for thin layers drying type due to its ease of manufacturing and economical aspects. However, the drawback of this dryer design is the non-uniformity in the required moisture content of end product. This work presents the development of multi chamber solar drying cabinet using numerical analysis. The main objective is to ensure uniform velocity distribution inside the multi chamber dryer. This aim has been achieved by series of modifications of design concepts based on the aerodynamic behavior of air flow. The results showed that four design phases to come out with optimum design configuration of the multi chamber drying cabinet. The velocity above the splitter has a significant difference of around 0.1 m/s at the end of splitters among the chambers. It is concluded from this result that the cross section flow area has an impact on the uniformity of velocity and a further modification is recommended.Multi tray solar dryer is commonly used for thin layers drying type due to its ease of manufacturing and economical aspects. However, the drawback of this dryer design is the non-uniformity in the required moisture content of end product. This work presents the development of multi chamber solar drying cabinet using numerical analysis. The main objective is to ensure uniform velocity distribution inside the multi chamber dryer. This aim has been achieved by series of modifications of design concepts based on the aerodynamic behavior of air flow. The results showed that four design phases to come out with optimum design configuration of the multi chamber drying cabinet. The velocity above the splitter has a significant difference of around 0.1 m/s at the end of splitters among the chambers. It is concluded from this result that the cross section flow area has an impact on the uniformity of velocity and a further modification is recommended.

Case Studies in Thermal Engineering, 2018

Solar thermal systems produce steam after being energized by solar parabolic trough concentrators... more Solar thermal systems produce steam after being energized by solar parabolic trough concentrators, are incorporated with a steam turbine-generator assembly to produce electricity. This study presents a code for prediction of performance, while undertaking preliminary plant-sizing for a variety of parabolic trough solar fields operating under nominal conditions. The code, named as PTPPPP (Parabolic Trough Power Plant Performance Predictor) consists of four blocks. The code allows prediction of variables including: heat loss coefficient, U L , aperture effective direct normal irradiance, I, heat gain, Q gain , and the thermal efficiency of stand-alone parabolic trough solar thermal power plant in commerce, η p. The conceptual design of the stand-alone parabolic trough solar involves: selection and sizing of system components, power generation cycles, working fluid types, and power block sizing. The input weather parameters and the operational parameters to the code have been acquired from in-situ measurements. The prediction results of the code have been found in good agreement with literature data with mean error of 0.18% in prediction of output power. In addition, this code is able to provide a flexibility in terms of temperature, heat transfer, and pressure range.

Energy and Buildings, 2011

Drying fruit, heating residential buildings and providing a hot water supply in villages all cons... more Drying fruit, heating residential buildings and providing a hot water supply in villages all consume energy. Using fossil fuel for these purposes creates pollution and costs too much. In contrast, the use of solar energy in these applications leads to a noticeable decrease both in pollution and investment costs. In this study, a new solar system was designed and tested in order to reduce energy usage in rural residential buildings and the food drying industry. As the peaks of energy consumption in the proposed system are not simultaneous, this new system is very effective in reducing energy consumption, controlling energy peaks and reducing environmental pollution. This system has the ability to provide the required energy in both summer and winter modes. In the summer mode, the energy supply is used for providing hot water and drying agricultural products, while in winter mode it is used for rural residences heating and hot water supply. Drying time has been varied between 51.23 and 42.45 h according to type of application, and average temperature difference between room and ambient is almost nearly 10 • C with different air heaters. The system includes energy supply and storage equipment, solar dryers, water collectors and rectangular, triangular, trapezoidal and double-pass with longitudinal fins air heaters. The system was tested in Iran for drying apricots, heating rural residential buildings and supplying hot water for domestic use, meanwhile, the energetic and exergetic efficiency of the system was calculated 37.3-61.3 and 3.2-9.7 respectively for different types of installations.

International Journal of Renewable Energy Research, 2016

The significance of this research is to fabricate a SWCNT/TiO2 composite that has the self-cleani... more The significance of this research is to fabricate a SWCNT/TiO2 composite that has the self-cleaning property to be coated on glass. It has been observed that the surface of the glass tends to get dirty and dusty with time. The objectives of this paper are to compare and analyze the transmittance and also the photocatalytic activity of the nanocomposite solutions prepared. The method used to fabricate this composite is sol-gel synthesis as it has a higher dispersion and is easiest way to use and the method used to coat the solution on substrate is spin coating method since it has a uniform coating compared to other methods. It is important to ensure that the solution prepared is transparent so as to ease the coating process. 20 different samples were fabricated using different SWCNT and TiO2 composition. In order to analyze transparency and photocatalytic activity, two different characterizations was conducted namely Fourier Transform Infrared Radiation spectroscopy (FTIR) for transm...

In this paper optical simulations based on Transfer Matrix Method (TMM) is developed to investiga... more In this paper optical simulations based on Transfer Matrix Method (TMM) is developed to investigate the performance of Carbon nanotube on silicon solar cells. Reflection of the incident photons by the silicon surface is a major source of losses for photovoltaic solar cell. However, these losses can be minimized by depositing an antireflection layer. Recently, antireflective coatings (ARCs) attract critical consideration for both their fundamental aspects and wide practical applications. The TMM solutions permit us to plot the optical reflectivity versus wavelengths and layer thicknesses. The optical refractive index and thicknesses of considered materials, which allowed us to have the lowest reflection, can be used to simulate the electrical properties of the cell with PC1D and Silvaco software in the future.

MATEC Web of Conferences

In recent years, energy consumption has become a critical issue in the developed and developing c... more In recent years, energy consumption has become a critical issue in the developed and developing countries. Residential buildings are one of the most users of energy in the construction sector that use the highest share of energy. This paper aims at evaluating the effect of four factors that are temperature, humidity, airflow and pressure on the cooling load in the residential buildings. To achieve this goal, statistical experimental design is used to determine the optimum setting of factors that result in optimum energy usage. Simulation software and energy analysis is used to simulate a two-storey building in Malaysia as the case of study. Final results showed that the temperature, humidity and interaction between them have the most significant effect on the energy cooling load. Moreover, to obtain the minimum value of cooling load the temperature and humidity should be equal to A=20 Celsius degree and B=60% respectively. In addition, the other two insignificant factors, airflow and pressure should be placed at the high level which are equal to C=3 cubic meters per hour, and D=6 Pascal (P) respectively.