Professional info
I am currently a PhD student in the Engineering department of the University of Cambridge. I'm working under the supervision of Dr. Stuart Scott.
Languages
Farsi
English
Refereed Journal Papers
1. Analysis of Maisotsenko open gas turbine power cycle with a detailed air saturator model
Mohammad Saghafifar; Mohamed Gadalla
Applied Energy 149, 2015, 338-353
With ever increasing cost of fossil fuels and natural gas, the improvement in gas turbine power cycle efficiency is needed due to the tremendous savings in fuel consumption. Water/steam injection is considered as one of the most popular power augmentation techniques because of its significant impact on the gas turbine performance. One of the recently suggested evaporative gas turbine cycles is the Maisotsenko open cycle for gas turbine power generation. In this paper, detailed thermodynamic analysis of this cycle is investigated with a thorough air saturator model. A comparative analysis is carried out to signify the advantages and disadvantages of Maisotsenko gas turbine cycle (MGTC) as compared with humid air gas turbine cycles. MGTC performance is evaluated based on a simple recuperated gas turbine cycle. In addition, sensitivity analysis is performed to investigate the effect of different operating parameters on the overall cycle performance. Finally, integrating an air saturator instead of a conventional heat exchanger in recuperated gas turbine cycles enhances the power plant performance such that an efficiency enhancement of 7% points and net specific work output augmentation of 44.4% are obtained.
2.Analysis of Maisotsenko open gas turbine bottoming cycle
Mohammad Saghafifar; Mohamed Gadalla
Applied Thermal Engineering 82, 2015, 351-359
Maisotsenko gas turbine cycle (MGTC) is a recently proposed humid air turbine cycle. An air saturator is employed for air heating and humidification purposes in MGTC. In this paper, MGTC is integrated as the bottoming cycle to a topping simple gas turbine as Maisotsenko bottoming cycle (MBC). A thermodynamic optimization is performed to illustrate the advantages and disadvantages of MBC as compared with air bottoming cycle (ABC). Furthermore, detailed sensitivity analysis is reported to present the effect of different operating parameters on the proposed configurations' performance. Efficiency enhancement of 3.7% is reported which results in more than 2600 tonne of natural gas fuel savings per year.
3.Innovative inlet air cooling technology for gas turbine power plants using integrated solid desiccant and Maisotsenko cooler
Mohammad Saghafifar; Mohamed Gadalla
Energy 87, 2015, 663-677
Gas turbine thermal efficiency has significant dependency on climatic conditions. Evaporative cooling is commonly utilized as an inlet air cooling technique in hot and dry climates though an increase in atmospheric humidity will considerably diminish its performance. Implementing desiccants to dehumidify air will enhance evaporative inlet cooling effectiveness. Furthermore, a recently commercialized cooler named Maisotsenko cooler can be integrated in gas turbine inlet air cooling to replace conventional evaporative coolers. In this paper, four different inlet air cooling systems employing turbine waste heat are proposed for gas turbine power augmentation in hot and humid climates such as UAE. Detailed sensitivity analysis is performed to investigate the impact of ambient air conditions and regeneration temperature on the inlet air cooling systems' effectiveness. Recommended inlet air cooling techniques are evaluated against more commonly used inlet air cooling systems under UAE climatic conditions. Finally, economic and transient analysis are accomplished to signify the most economical inlet air cooling system that is most suitable for UAE gas turbine power augmentation. Maisotsenko evaporative desiccant inlet air cooling with life savings of 31.882 MUS$ is the most economically justified inlet cooling technique for a 50 MWe gas turbine power plant in UAE with life span of 25 years.
4.Comparative analysis of power augmentation in air bottoming cycles
Mohammad Saghafifar; Andreas Poullikkas
International Journal of Sustainable Energy 36 (1), 2017, 47-60
The air bottoming cycle (ABC) is a proposed plant configuration in which the steam turbine bottoming cycle in conventional combined power plants is replaced by another gas turbine cycle. Nevertheless, ABC's relatively low efficiency reduces the likelihood of having an ABC power plant in the near future. In this research work, steam injection in the topping cycle combustion chamber and supplementary firing are recommended to improve ABC's performance. Three different configurations of ABC, including simple ABC, ABC with steam injection, and ABC with supplementary firing, are investigated. A thermo-economic analysis is performed to study the effects of the proposed power augmentation approaches thermodynamically and economically. Moreover, optimisation is carried out with the objective of minimising the total cost of the plant for different configurations. Furthermore, a multi-objective optimisation is performed and the results are presented to further understand the trade-off between higher efficiency and lower operating cost.
5.Thermo-economic optimization of air bottoming cycles
Mohammad Saghafifar; Andreas Poullikkas
Journal of Power Technologies 95(3), 2015, 211-220
In this work a thermo-economic optimization analysis on two air bottoming cycle (ABC) configurations with and without intercooler in the bottoming cycle is carried out. In particular a themo-economic optimization modeling is developed and the effect of the mass flow rate ratio of bottoming cycle air mass flow rate with respect to the topping cycle air mass flow rate is examined on both the ABC plant efficiency as well as total operation cost.
6.Performance assessment of integrated PV/T and solid desiccant air-conditioning systems for cooling buildings using Maisotsenko cooling cycle
Mohammad Saghafifar; Mohamed Gadalla
Solar Energy 127, 2016, 79-95
Hot summer days coincide with high solar insolation periods and high peak demands in the UAE. Solid desiccant air conditioning systems are capable of utilizing low-grade sources of energy such as solar energy. In this paper, two new air conditioning systems combining solid desiccant and Maisotsenko coolers are examined for use in humid climates such as the UAE. Solar energy in the form of a solar PV/T module is selected as the primary source of energy to operate the desiccant air cooling systems while an auxiliary heater is devised for supplementary air heating. A detailed thermodynamic analysis is performed to illustrate and evaluate the proposed air conditioning systems’ performance in the UAE under different operating conditions. A comparative analysis is carried out to signify the advantages and disadvantages of integrating the Maisotsenko cooler with conventional desiccant air conditioning units. Furthermore, a seasonal analysis is conducted to examine the performance of the proposed systems throughout a summer day in Abu Dhabi. Average COP for two proposed configurations during the investigated period are 0.2495 and 0.2713. Furthermore, their corresponding solar shares are 32.2% and 36.5%. With PV/T module collectors’ area of 681.0 m2 and 656.3 m2, annual electricity generation of 145.0 MWh and 139.7 MWh are reported.
7.Thermo-economic analysis of conventional combined cycle hybridization: United Arab Emirates case study
Mohammad Saghafifar; Mohamed Gadalla
Energy Conservation and Management 111, 2016, 358-374
Extensive investigations have been conducted to find a replacement for fossil fuels and natural gases in power generation industries. Solar energy is one of the most promising solution to a more environmentally friendly power production technology. In particular, concentrated solar power technologies are displaying significant potential for electricity production. United Arab Emirates hot and sunny climate is an indication of the great potential it possesses for hybrid and solar only power plant implementation. In this paper, power plant hybridization feasibility in the United Arab Emirates is taken under extensive investigation. Moreover, a thermo-economic optimization is performed for the installment of a new 50 MWe hybrid conventional combined cycle power plant in the United Arab Emirates. In addition, hybridization of an already existing conventional combined cycle power plant is comprehensively investigated by utilizing levelized cost of electricity, payback period, life cycle saving, and net present value approaches. The hybrid conventional combined cycle power plant optimum levelized cost of electricity and net present value are 77.7 US$/MWh and -34.918 MUS$, respectively. Additionally, the plant solar share and specific carbon dioxide emission are 8.87% and 371.9 kgCO2/MWh, respectively.
8. Performance assessment and transient optimization of air precooling in multi-stage solid desiccant air conditioning systems
Mohamed Gadalla; Mohammad Saghafifar
Energy Conservation and Management 119, 2016, 187-202
Renewable energy is one of the most promising solutions to both energy and global warming crisis. Energy consumption can be minimized considerably by utilizing solar energy in air conditioning systems operation. One of the popular solar air conditioning technologies is desiccant air conditioning. Nonetheless, conventional desiccant air conditioning systems have a relatively low coefficient of performance (COP). In consequence, two-stage desiccant air-conditioning systems are proposed to improve desiccant air conditioning systems’ COP. Moreover, a recently commercialized cooling method named Maisotsenko cooling cycle which is capable of cooling air near to its dew point temperature is considered to be integrated within the proposed multi-stage desiccant cooling systems.
In this paper, three new two-stage desiccant air conditioning systems incorporating Maisotsenko cooling cycle are proposed and investigated in details for hot and humid climates such as UAE. Furthermore, air precooling is considered to improve two stage desiccant air conditioning systems’ COP. Moreover, full transient analysis and optimization are carried out in UAE within June–October. The proposed system can minimize the required solar heating during noon time as the ambient air dry bulb temperature rises. Average COP of the system during electricity load peak hours (10:00–14:00) for all five considered and combined months is 1.77. Average rate of heat input required to operate the system and average building cooling load are determined to be 100.3 kW and 46.2 kW, respectively. Therefore, system average COP is computed to be 0.46.
9. Thermo-economic analysis of air bottoming cycle hybridization using heliostat field collector: A comparative analysis
Mohammad Saghafifar; Mohamed Gadalla
Energy 112, 2016, 698-714
Nowadays, climate change has become a vital issue prompting investigations for increasing the share of renewable energy employment in power generation industry. Solar energy is arguably the most favorable solution for a greener power generation technology. With the current level of maturity, solar energy contribution is limited due to intermittency and storage issues. A possible solution to the aforementioned difficulties is power plant hybridization. In this paper, thermo-economic optimization of a hybrid air bottoming cycle (ABC) power plant is accomplished with the objective of minimizing the levelized cost of electricity. The aforementioned hybrid ABC optimization results are compared with a hybrid conventional combined cycle power plant to identify the most cost effective combined cycle configuration for a 50 MWe hybrid power plant. Finally, an already existing ABC power plant hybridization is investigated utilizing payback period, life cycle saving, and levelized cost of electricity approaches.
10.Thermo-economic Analysis of Air Saturator Integration in Conventional Combined cycles
Amr Omar; Mohammad Saghafifar; Mohamed Gadalla
Applied Thermal Engineering 107, 2016, 1104-1122
This paper presents a detailed thermodynamic and economic analysis on a conventional combined power cycle integrated with the Maisotsenko heat exchanger. The results obtained were compared with the conventional combined cycle to see the impact of the Maisotsenko technology on the thermal efficiency, air mass flowrate required and the levelized cost of electricity. A Maisotsenko heat exchanger is placed at the inlet of the air compressor to cool down the air to reduce the power input and the air flowrate required. As a results smaller turbomachinery equipment are installed, which aids in decreasing the capital cost. In addition, another Maisotsenko heat exchanger is placed before the combustor to saturate the air streams to allow effective heat recovery from the turbine gasses at the recuperator. This will help in reducing the fuel burnt in the combustion chamber, thus reducing the operating cost. It was found that the Maisotsenko combined cycle (MCC) has a higher overall thermal efficiency than the conventional combined cycle (CC) by 6%, which reduced the levelized cost of electricity LCOE by 3.8 US$/MWh. However, due to the nature of the Maistosenko technology, 19.55 kg/s of water is required to saturate the air and provide an effective heat recovery from the exhaust gasses. Finally, a parametric analysis was conducted on the MCC and the CC to compare system behaviors when certain parameters change.
11. Thermo-economic and comparative analyses of two recently proposed optimization approaches for circular heliostat fields: Campo radial-staggered and biomimetic spiral
Mohamed Gadalla; Mohammad Saghafifar
Solar Energy 136, 2016, 197-209
In this paper, comparative analyses between two newly proposed circular heliostat field layout designs, i.e. Campo radial-staggered and biomimetic spiral layouts are carried out. Moreover, different optimization objectives including annual weighted efficiency, annual unweighted efficiency, and levelized cost of energy are considered for field layout optimization. In addition, the effects of different design variables, such as the central tower height, number of heliostats in the field, receiver’s dimensions and size of the mirrors on the field thermal and economical capabilities are investigated. Finally, the analysis results indicate that optimum weighted efficiency for Campo radial-staggered and biomimetic spiral layouts are 61.6% and 61.5%, whereas the optimum levelized cost of energy for both methods are 32.4 US$/MWh.
12.Thermo-economic analysis of recuperated Maisotsenko bottoming cycle using triplex air saturator: Comparative analyses
Mohammad Saghafifar; Amr Omar; Sepehr Erfanmoghaddam; Mohamed Gadalla
Applied Thermal Engineering 111, 2017, 431-444
A recently recommended combined cycle power plant is to employ another gas turbine cycle for waste heat recovery as an air bottoming cycle (ABC). There are studies conducted to improve ABC’s thermodynamic performance utilizing commonly power augmentation methods such as steam/water injection. In particular, it is proposed to employ Maisotsenko gas turbine cycle as a bottoming cycle, i.e. Maisotsenko bottoming cycle (MBC). Due to the promising performance of the MBC configuration, it is decided to investigate a recuperated MBC (RMBC) configuration by recommending the triplex air saturator. In this way, the air saturator consists of three sections. The first section is an indirect evaporative cooler whilst the other two sections are responsible for heat recovery from the topping and bottoming cycle turbines exhaust. In this paper, a thermodynamic analysis is carried out to study the main merits and demerits of RMBC against MBC configuration. Next, thermodynamic and thermo-economic comparative evaluations between MBC and RMBC are presented. Thermodynamic optimization results indicate that the maximum achievable efficiency for MBC and RMBC incorporation in a simple gas turbine power plant are 39.40% and 44.73%, respectively. Finally, thermo-economic optimization shows that the optimum levelized cost of electricity for MBC and RMBC power plants are 62.922 US$/MWh and 58.154 US$/MWh, respectively.
13.Thermo-economic evaluation of water-injected air bottoming cycles hybridization using heliostat field collector: Comparative analyses
Mohammad Saghafifar; Mohamed Gadalla
Energy 119, 2017, 1230-1246
Solar energy is one of the alternative sources of energy which is clean and available in abundant. Nevertheless, one of the main difficulties associated with solar energy utilization is the intermittency and storage. A possible solution to the aforementioned difficulties is power plant hybridization. Additionally, air bottoming cycle is an alternative plant configuration which is more economical for small scale power generation than conventional combined cycle. To further improve the air bottoming cycle thermo-economic performance, water injection in the bottoming cycle air is proposed. In this paper, addition of an air bottoming cycle with and without water injection in an already existing hybrid gas turbine cycle is investigated. Moreover, a thermo-economic optimization is conducted for a hybrid air bottoming cycle power plant with water injection in the bottoming cycle air. Next, power plant hybridization for an already existing air bottoming cycle power plant with water injection is assessed by utilizing three thermo-economic assessment approaches comprising levelized cost of electricity, payback period and life cycle saving. The acquired results indicate the advantages of water injection to improve the bottoming cycle heat recovery capability and plant’s levelized cost of electricity. Noting that the plant’s levelized cost of electricity is improved by 0.7 US$/MWh as water injection in the bottoming cycle is introduced.
14.Thermo-economic optimization of hybrid solar Maisotsenko bottoming cycles using heliostat field collector: Comparative analyses
Mohammad Saghafifar; Mohamed Gadalla
Applied Energy 190, 2017, 686-702
Hybridization is a newly proposed concept in which solar thermal energy provides a portion of the required thermal input instead of fossil fuels and natural gases. Storage and intermittency concerns regarding solar energy make hybridization a viable solution to increase renewable energy share in power generation. Maisotsenko gas turbine cycle is a recently proposed humid air turbine cycle which can be implemented as a bottoming cycle to a topping gas turbine cycle as Maisotsenko bottoming cycle. In this paper, Maisotsenko bottoming cycle power plant hybridization is thoroughly investigated using heliostat field collector. First, a thermo-economic optimization is carried out for a hybrid Maisotsenko bottoming cycle power plant in the United Arab Emirates. Furthermore, the optimization results for Maisotsenko bottoming cycle are evaluated against the acquired results for hybrid air bottoming cycle and conventional combined cycle. Finally, different levels of hybridization are considered for an already existing non-hybrid Maisotsenko bottoming cycle power plant by applying different thermo-economic assessment methods. Comparative analyses indicate that Maisotsenko bottoming cycle is a more economical alternative for bottoming cycle implementation as compared with other investigated configurations with optimum levelized cost of electricity of 75.330 US$/MWh.
15.Energy and Exergy analyses of integration of pulse combustor in air bottoming cycle power plants
Mohamed Gadalla; Mohammad Saghafifar
Applied Thermal Engineering 121 2017, 674-687
Air bottoming cycle (ABC) is one of the combined cycle configurations which can be implemented for small scale power plants. Nonetheless, ABC’s low efficiency might be the main reason preventing the commercialization of this novel idea. One of the possible modifications that might be a breakthrough in enhancing the ABC’s efficiency is the integration of a pulse combustor. In this paper, integration of pulse combustor in ABC configuration is proposed. Two different configurations for pulse combustor incorporation in ABC are recommended including pulse combustor replacing topping cycle combustion chamber and pulse combustor integration as a supplementary firing in the bottoming cycle. Energy analysis is performed by manipulating different design variables and study their effect on both thermal efficiency and net specific work output. Furthermore, exergy analysis is carried out pinpointing the sources of irreversibility within the configurations. Moreover, thermodynamic optimization is performed to identify the maximum power enhancement due to the implementation of the pulse combustion. Integration of pulse combustor in the topping cycle can improve efficiency to 50.8% whereas maximum possible ABC’s efficiency is 43.6%. Furthermore, pulse combustor employment as a supplementary firing in the bottoming cycle optimum efficiency is only 41.8%.
16. A concise overview of heliostat fields-solar thermal collectors: Current state of art and future perspective
Mohamed Gadalla; Mohammad Saghafifar
International Journal of Energy Research 42(10), 2018, 3145-3163
Heliostat field or solar tower collector is one of the most promising concentrated solar power technologies available in the market. Due to its high operating temperature, heliostat field collector can be implemented in a wide range of applications from solar power generation to industrial commodity production. There are several currently operating, under construction, and planned heliostat fields around the world. In this paper, a brief overview of the current state of the art, applications, assessment methods, future perspective, and methods of improvement are discussed.
17. Economic feasibility and environmental benefits of developing grid-connected photovoltaic plants in the southern coast of Iran
Kasra Mohammadi; Mahmoud Naderi; Mohammad Saghafifar
Energy, 156, 2018, 17-31
In this study, the potential of developing 5 MW gird-connected PV power plants in eight selected cities in the southern coast of Iran is evaluated from technical, financial and environmental viewpoints. Different sun-tracking modes including fixed tilt, 1-axis and 2-axis systems are investigated. A sensitivity analysis is conducted to examine the impact of different important parameters and identify when investment is more profitable. The results demonstrate that development of proposed PV plants is very promising in all cities and using 1-axis tracking system is the most economical option. Under current guaranteed feed-in tariff (FIT) in Iran, the levelized cost of electricity for fixed tilt, 1-axis and 2-axis tracking modes PV plants for all cities are obtained in the range of 112.3-125.6 $/MWh, 103.0-117.3 $/MWh and 107.2-122.5 $/MWh, respectively. The analysis shows that other financial incentives such as a bank loan and carbon credit substantially improve the economic attractiveness of the project. The calculated CO2 emission abatement and external cost saving due to employment of the PV plants demonstrate that the proposed PV projects have appealing environmental benefits. This study shows that the southern coast of Iran has a huge potential and actual market opportunities for investors to develop grid-connected PV projects.
18. Thermo-economic evaluation of several feasible modifications to the gas power plant with air bottoming combined cycle for different applications
Kasra Mohammadi; Mohammad Saghafifar; Jon G. McGowan
Energy Conversion and Management, 172, 2018, 619-644
Multigeneration technologies provide a significant potential for efficient, sustainable and economical generation of multiple useful products. Gas turbine with air bottoming combined cycle is an attractive combined cycle configuration for small scale power generation (less than 50 MW). A favorably high temperature waste heat exiting both flue gas and air sides of gas turbine with air bottoming combined cycles presents a considerable opportunity to further recover the available heats for power generation and multigeneration. In this study, eight different hybrid systems are proposed for further heat recovery of a gas turbine with air bottoming combined cycle to generate different useful products including power, fresh water, cooling, hot water, and industrial process heat. For this purpose, an optimized 50 MW gas turbine with air bottoming combined cycle is integrated with several thermodynamic cycles and components such as carbon dioxide transcritical Rankine cycle, water-lithium bromide absorption cooling, ammonia-water absorption refrigeration, thermal vapor compression-multi effect distillation, heat recovery steam generator, and gas (air)-water heat exchanger. The performance of the proposed hybrid configurations is evaluated from both thermodynamic and economic viewpoints. The obtained findings demonstrate that utilization of available waste heats in a gas turbine with air bottoming cycle is very beneficial to generate a significant amount of different useful products with a very favorable cost. The outcomes of this study can be useful for development of proposed integrated systems for both residential and industrial applications.
19. A critical assessment of thermo-economic analyses of different air bottoming cycles for waste heat recovery
Mohammad Saghafifar; Mohamed Gadalla
International Journal of Energy Research, 2018
Steam turbine cycle’s low operating temperature makes it suitable for waste heat recovery applications. Even though conventional combined cycles, i.e. topping gas turbine and bottoming steam turbine cycles, are thermodynamically efficient, they are not the most economical alternatives for power generation with capacities less than 50 MWe. A recently proposed alternative is to utilize a bottoming gas turbine cycle in form of an air bottoming cycle. In this study, an overview of air bottoming cycle is presented. Based on the discussed studies, it is decided to further evaluate the merits of water injection in the bottoming cycle air stream by using either a humidifier or an air saturator. Thermo-economic analysis and optimization are performed to evaluate simple and water injected air bottoming cycles against steam bottoming cycles. Results indicate that conventional combined cycles can achieve the highest thermal efficiency of about 48%. Whilst water injected air bottoming cycle with air saturator is the most cost effective combined cycle configuration and most efficient air bottoming cycle with levelized cost of electricity and energy efficiency of 64.41 US$/MWh and 39-40%, respectively, followed by the water injected air bottoming cycle with humidifier and simple air bottoming cycle with reported levelized cost of electricity of 65.75 US$/MWh, 66.36 US$/MWh, respectively. Steam bottoming cycle has the highest levelized cost of electricity of 68.88 US$/MWh.
20. A review of unconventional bottoming cycles for waste heat recovery: Part I -Analysis, design, and optimization
Mohammad Saghafifar; Amr Omar; Kasra Mohammadi; Adnan Alashkar; Mohamed Gadalla
Energy Conversion and Management, 2018
In this paper, an extensive overview of unconventional waste heat recovery power cycles is presented. The three-unconventional waste heat recovery bottoming cycles discussed in this paper are the air bottoming cycle, carbon dioxide-based power cycles and Kalina bottoming cycle. The review paper is divided into two parts; first part is about a detailed discussion of energy, exergy, economic analysis, as well as reviewing part load analysis, component design, power augmentation and comparative studies. Whereas, the second part of the review paper demonstrate and thoroughly review the applications of the aforementioned unconventional bottoming cycles, including renewable energy sources.
According to the literature, it was found that the air bottoming cycle is not as competitive when compared to the conventional bottoming cycle, such as the steam Rankine cycle. Nevertheless, air bottoming cycle can be economically competitive for low system capacities. Furthermore, CO2 power cycles have shown better performance in terms of energetic and exergetic analyses when compared to the conventional bottoming cycles. The transcritical and supercritical CO2 power cycles excel to recover low and medium grade waste heat, respectively. Finally, Kalina bottoming cycle was found to be competitive to recover the low-grade waste heat when compared to organic Rankine cycle. In addition, optimizing the ammonia-water concentrations at different stages of the cycle has the most notable effect in improving the cycle’s performance.
21. A review of unconventional bottoming cycles for waste heat recovery: Part II –Applications
Amr Omar; Mohammad Saghafifar; Kasra Mohammadi; Adnan Alashkar; Mohamed Gadalla
Energy Conversion and Management, 2018
This paper presents an extensive overview of unconventional waste heat recovery bottoming cycles including air bottoming cycle, Carbon dioxide-based power cycles and Kalina bottoming cycle. Noting that this is a two-part review paper, first part mainly focuses on the technical aspects of these waste heat recovery methods by reviewing studies on energy, exergy, economic analyses of these systems, as well as reviewing part load analysis, component design, power augmentation and comparative analysis between conventional and unconventional systems. This part demonstrates and thoroughly review the applications of the aforementioned unconventional bottoming cycles, including renewable energy sources. Eleven applications were discussed including renewable energy sources integration, internal combustion engine, CCHP systems, carbon capture operation, offshore platforms, gas transport, fuel cells, and marine industry. It was concluded that air bottoming cycle is not thermodynamically competitive with other bottoming cycles due to its high operating temperature. Whilst CO2 and Kalina cycles were competitive with conventional waste heat recovery methods such as steam and organic Rankine cycles for medium-to-low grade waste heat sources.
Skills
MATLAB
EES
LATEX
3ds max
C
FEMLAB
Inventor
AutoCAD
ANSYS
Publication
1. An extensive overview of heliostat field layout design and optimization mathematical formulation
Mohammad Saghafifar; Mohamed Gadalla
Renewable and Sustainable Energy Reviews (Under review: 10th January 2018)
Reference Number: RSER-18-00541
In this paper, a review of different methods for heliostat field layout design and optimization is presented. Due to importance of heliostat positioning in the field, different methods and optimization techniques have been proposed and investigated. Initially, a brief discussion about the history, basic of operation, applications and operational heliostat fields is presented. Afterward, optical, economic, and annual performance assessments mathematical models for heliostat fields are discussed. Moreover, various techniques for heliostat positioning in order to maximize the its thermal and economic performance indicators mirrors are laid out.
2. Thermo-economic analysis and optimization of heliostat fields using AINEH code: Analysis of Implementation of Non-Equal Heliostats (AINEH)
Mohammad Saghafifar; Mohamed Gadalla; Kasra Mohammadi
Renewable Energy (Under review: 4th June 2018)
Reference Number: RENE-D-18-02191
In this paper, a new heliostat field design and optimization technique is proposed. The unique aspect of the proposed approach is the code ability to design the field with non-equal heliostats. It is believed that designing a field of non-equal heliostats may lead to improving the energy and economic performance of a heliostat field. This idea has been put to test by developing a new code called AINEH (analysis of implementation of non-equal heliostats). Firstly, the mathematical models developed in AINEH code are comprehensively discussed by presenting the initial layout generation model, expansion technique, economic model, optimization approach, and objectives. Moreover, parametric analysis is carried out to identify the effect of different design parameters. Finally, AINEH code is used to re-design PS10 by conducting a thermo-economic optimization. Energy optimization results show that PS10 annual weighted efficiency can be improved by 0.32% points from 68.91% to 69.23% in case of using AINEH code. In addition, field’s levelized cost of energy (LCOE) can be reduced by 1.3 US$/MWh (6.5%) from 19.9 US$/MWh to 18.6 US$/MWh.
3. A critical overview of solar assisted carbon capture systems: Is solar always the solution?
Mohammad Saghafifar; Samuel Gabra
International Journal of Greenhouse Gas Control (Under review: 16th September 2018)
Reference Number: JGGC_2018_601
In this review paper, an extensive overview of solar assisted carbon capture systems is presented. The focus of this paper is on possible integration schemes between solar thermal collectors and carbon capture systems. Initially, various aspects of concentrating and non-concentrating solar thermal collectors are presented. Similarly, carbon capture technologies and possible gas separation techniques are reviewed. Afterward, solar assisted carbon capture systems are classified into post-combustion, pre-combustion, and oxyfuel combustion and discussed in detail. In addition, a new factor is introduced to assess the feasibility of solar assisted carbon capture systems against other competitive technologies. Finally, future perspective and possible research directions are discussed.
4. Thermoeconomic analysis of multi-stage recuperative Brayton power cycles: Part I- Hybridization with a solar power tower system
Kasra Mohammadi; Jon G. McGowan; Mohammad Saghafifar
Energy Conversion and Management (Under review: 31st October 2018)
Reference Number: ECM-D-18-06789
This study, which is the first part of a study on multi-stage recuperative Brayton cycle configurations, evaluates the thermodynamic and economic feasibility of hybridizing different multi-stage recuperative Brayton cycle configurations with a solar power tower using a pressurized air receiver. In part 2 of this work, the waste energy recovery from non-solar multi-stage recuperative Brayton cycle configurations is evaluated from both thermodynamic and economic viewpoints. The results of this first part of work show that the employment of multi-stage recuperative Brayton cycle configurations leads to a significant increase in the thermal efficiency and a reduction in the fuel consumption, CO2 emissions and levelized cost of electricity (LCOE) for both non-solar and hybrid solar power plants. For non-solar power plants, the cycle configuration with 4 stages of intercooling and reheating showed the highest thermal efficiency (53.6%) and the lowest LCOE ($57.80/MWh) leading to a 32% increase and a 17% decrease compared to a simple recuperative Brayton cycle. The results of this study demonstrate that hybridization of multi-stage recuperative Brayton cycle configurations with a power tower plant with a pressurized air receiver is not economically and environmentally attractive at current time. The main reasons are technological limitations of pressurized air receiver due to lower temperature (1223K) and pressure (30 bar) as well as the high cost of solar power tower system (especially the heliostats). Technological advances in the future that enables a higher output temperature and pressure for the receiver as well as reduction in the heliostats and receiver costs would certainly be useful in improving the economic and environmental attractiveness of such hybridizations.
Submitted Journal Publications
1.Integrating a pulse combustor in air bottoming cycle power plants (PDF)
Mohamed Gadalla; Mohammad Saghafifar
In proceedings of 7th International Exergy, Energy and Environment Symposium, 2015, Valenciennes, France
With ever increasing cost of fossil fuels and natural gases, power generation with lower fuel consumption and capital investment cost is subjected to extensive investigation. Conventional combined cycle including a topping gas turbine and a bottoming steam turbine is the most efficient combined cycle configuration for power generation. However, having a condenser and heat recovery steam generator in the bottoming cycle results in high capital investment cost. Conventional combined cycle’s high capital investment requirements make it unattractive for small scale power plants. Air bottoming cycle (ABC) is one of the combined cycle configurations which can be implemented for small scale power plants. Nonetheless, ABC’s low efficiency might be the main reason preventing the commercialization of this novel idea. One of the possible modifications that might be a breakthrough in enhancing the ABC’s efficiency is the integration of pulse combustor.
In this paper, integration of pulse combustor in ABC configuration is proposed. Two different configurations for pulse combustor incorporation in ABC are recommended including pulse combustor replacing topping cycle combustion chamber and pulse combustor integration as a supplementary firing in the bottoming cycle. Sensitivity analysis is performed by manipulating different design variables and study their effect on both thermal efficiency and net specific work out. Moreover, thermodynamic optimization is performed to achieve the highest power enhancement resulting from the implementation of pulse combustion for cycle configuration. Integration of pulse combustor in the topping cycle can improve efficiency to 50.8% whereas maximum possible ABC’s efficiency is 43.6%. Pulse combustor employment as a supplementary firing in the bottoming cycle maximum achievable efficiency is only 41.8%.
2.Solid Desiccant Air Conditioning Systems Using Maisotsenko Cooling Cycle (PDF)
Mohammad Saghafifar; Mohamed Gadalla
In Proceedings of third International Conference on Water, Energy, and the Environment,
2015, Sharjah, United Arab Emirates
Air conditioning systems are responsible for a gigantic portion of energy consumption in the UAE. Specially, UAE’s temperature might reach to extremely high temperatures of 50oC during summer seasons. Fortunately, hot summers are coincided with high solar insolation periods and high peak demands. Therefore, it is wise to utilize solar energy for air conditioning systems to reduce the electricity consumption associated with the needs of air conditioning operation. Solid desiccant air conditioning systems are capable of exploiting low grade sources of energy such as solar for their operation.
Direct and indirect evaporative cooling are the most commonly used cooling methods implemented in solid desiccant air conditioning systems. The cooling best performance of these types of cooling methods is limited by the air wet bulb temperature and relative humidity. On the other hand, Maisotsenko cooling cycle is a recently commercialized cooling system capable of cooling air to its dew point temperature. Coupling Maisotsenko cooler with a solid desiccant enables the suggested cooling systems to be employed in humid conditions such as in UAE.
In this paper, two new air conditioning systems combining solid desiccant and Maisotsenko cooler are proposed and investigated for humid climates such as in UAE. Solar energy is selected as the primary source of energy to operate the desiccant air cooling systems. Detailed thermodynamic analysis is performed to illustrate and evaluate the proposed air conditioning systems performance in the UAE under different operating conditions. A comparative analysis is carried out to signify the advantages and disadvantages of integrating the Maisotsenko cooler with conventional air condition systems. Furthermore, a transient analysis is executed to examine the performance of the proposed systems throughout a day in summer for Abu Dhabi weather data. The results demonstrate the benefits of integrating Maisotsenko coolers with solid desiccants as a considerably efficient air conditioning system. Finally, Transient analysis illustrates that both MDVC and MDRC are capable of efficient operation in Abu Dhabi worst weather conditions without any difficulties.
3.Improvement in spiral heliostat field layout thermo-economic performance by field zoning implementation
Mohammad Saghafifar; Mohamed Gadalla
ASME 2016 Power and Energy Conference and Exhibition,
2016, Charlotte North Carolina , United States
Arguably, the most complicated and problematic mathematical formulation for solar collectors belongs to the heliostat field collectors. Consequently, extensive researches are carried out in order to develop several codes capable of providing heliostat field analysis and optimization. Noting that most of the aforementioned heliostat field codes are developed based on the radial-staggered field layout which is arguably the most popular and widely implemented heliostat field configuration in the literature. Nevertheless, a ground-breaking heliostat field layout based on the spiral patterns of phyllotaxis discs is recently proposed. It was argued that the transition between the areas with high and low heliostat field density is not continuous in radial-staggered configuration. In a study by the authors, the spiral and radial-staggered field layouts thermo-economic analyses are compared and the results points to the superiority of the radial-staggered layout. Nevertheless, it is believed that utilizing two design variables might be only sufficient for small number of mirrors. Therefore, more design variables must be implemented to fully control different areas of the field for larger capacity heliostat fields. In this paper, spiral field zoning is proposed and its impact on the spiral heliostat field layout performance is assessed. By dividing the heliostat field into multiple zones, each zone is designed with a set of design variables (two design variables). Consequently, the impacts heliostat field zoning might have on the field thermo-economic performance are investigated.
4.Performance assessment and transient optimization of multi-stage solid desiccant air conditioning systems with building PV/T integration
Mohamed Gadalla; Mohammad Saghafifar
SPIE Optics + Photonics for Sustainable Energy,
2016, San Diego, United States
One of the popular solar air conditioning technologies is desiccant air conditioning. Nonetheless, single stage desiccant air conditioning systems’ coefficient of performance (COP) are relatively low. Therefore, multi-stage solid desiccant air conditioning systems are recommended. In this paper, an integrated double-stage desiccant air conditioning systems and PV/T collector is suggested for hot and humid climates such as the UAE. The results for the PV/T implementation in the double-stage desiccant cooling system are assessed against the PV/T results for a single-stage desiccant air conditioning system. In order to provide a valid comparative evaluation between the single and double stage desiccant air conditioning systems, an identical PV/T module, in terms of dimensions, is incorporated into these systems. The overall required auxiliary air heating is abated by 46.0% from 386.8 MWh to 209.0 MWh by replacing the single stage desiccant air conditioning system with the proposed double stage configuration during June to October. Moreover, the overall averaged solar share during the investigated months for the single and double stage systems are 36.5% and 43.3%.
5.Selecting a proper design period for heliostat field layout optimization using Campo code
Mohammad Saghafifar; Mohamed Gadalla
SPIE Optics + Photonics for Sustainable Energy,
2016, San Diego, United States
In this paper, different approaches are considered to calculate the cosine factor which is utilized in Campo code to expand the heliostat field layout and maximize its annual thermal output. Furthermore, three heliostat fields containing different number of mirrors are taken into consideration. Cosine factor is determined by considering instantaneous and time-average approaches. For instantaneous method, different design days and design hours are selected. For the time average method, daily time average, monthly time average, seasonally time average, and yearly time averaged cosine factor determinations are considered. Results indicate that instantaneous methods are more appropriate for small scale heliostat field optimization. Consequently, it is proposed to consider the design period as the second design variable to ensure the best outcome. For medium and large scale heliostat fields, selecting an appropriate design period is more important. Therefore, it is more reliable to select one of the recommended time average methods to optimize the field layout. Optimum annual weighted efficiency for heliostat fields containing 350, 1460, and 3450 mirrors are 66.14%, 60.87%, and 54.04%, respectively.
6.A thermoeconomic comparative analysis between different approaches of specific carbon dioxide emission reduction for a simple gas turbine power plant
Mohammad Saghafifar; Mohamed Gadalla
In proceedings of 9th International Exergy, Energy and Environment Symposium,
2017, Split, Croatia
Multiple reports indicate the considerable rate of growth in world’s energy demands. With the ongoing concerns about climate change and the considerable contribution of power generation industry in carbon dioxide emission, it is necessary to reduce the rate of carbon dioxide emission from power generation systems, immediately. In this study, three different approaches for a simple gas turbine power plant carbon dioxide emission reduction are recommended. The proposed methods include inlet air cooling with a mechanical chiller, steam bottoming cycle integration and hybridization of power plants using heliostat field collector. Steam bottoming cycle implementation reduces the plant specific CO2 emission by about 212-217 kgCO2/MWh (34-35%). Moreover, it is concluded that inlet air cooling technique manages to achieve improvement in both environmental and economic aspects of the plant even in a small scale power generation system. Furthermore, hybridization is the most expensive approach considered in this study.
7. Thermodynamic Analysis and Design of a Heliostat Field to Co-Produce Hydrogen and Electricity
Dona P. U. Madurawala; Mohammad Saghafifar; Mohamed Gadalla
ASME 2017 International Mechanical Engineering Congress and Exposition,
2017, Tampa, Florida, USA,
This paper investigates the use of hydrogen along with natural gases and solar energy to power a 50 MW power plant in the United Arab Emirates. Sudden changes in the climate have shifted the focus of scientists to formulate solutions to global warming and environmental pollution. Hence, numerous researches are being carried out on various renewable energy sources, such as solar energy and hydrogen. This study examines how the power generation, carbon dioxide (CO2) emission and the fuel consumption of the power plant is affected by the use of hydrogen, solar energy and natural gases. The power plant under investigation consisted of a hybrid conventional combined cycle whose bottoming cycle was allocated for the production of hydrogen during the day. The hydrogen that was produced was used at night to power the topping cycle to generate electricity. Solar energy was captured through concentrated solar power technology, while hydrogen was produced by a water electrolysis process. An extensive investigation of the performance of the power plant revealed that its annual hydrogen share was 7%, solar share 20% and natural gas share 73%. In addition, the annual CO2 emission and fuel consumption was found to be 394.1 kgCO2/MWhe and 58412 tonne respectively.
Conference Presentations
University of Cambridge
2017-present
PhD in Engineering
Commenced in October 2017
Expected Graduation in October 2020
American University of Sharjah, United Arab Emirates
2012 - 2015
Master of Science in Mechanical Engineering
Commenced in September 2012
Graduated in December 2015
Earned Credits: 30/30, CGPA: 4/4
American University of Sharjah, United Arab Emirates
2008 - 2012
Bachelor of Science in Mechanical Engineering
Commenced in August 2008
Graduated in July 2012
Earned Credits: 140/140, CGPA: 3.71/4