Energy, exergy, and economic analysis of a geothermal power plant

The current study aimed at designing a geothermal power plant in the Nonal area in Damavand district for simultaneous generation of thermal energy the electric power in the network of Damavand City and a part of Tehran province, the organic working fluid for the above cycle is R245fa which is a non-flammable fluid of dry type. The values of energy efficiency, exergy, the net rate of entropy change, and the specific output power were calculated as 18.2%, 21.3%, 172.97 kW/K, and 31.43 kJ/kg, respectively. The cost of drilling a well, as well as designing and construction of Damavand’s geothermal power plant, were calculated to be 4.2 and 521.5 million (USD), respectively. Also, the cost per generation of each kW/h of power in Damavand power plant was 17 cents. The estimated payback time is calculated as 15 years. The analysis of the cycle in different months of the year showed that exergy efficiency has little change. The only significant effect of temperature changes was on the exergy efficiency as approximately a change of 2% can be seen during a year.Cited as: Kazemi, H., Ehyaei, M.A. Energy, exergy, and economic analysis of a geothermal power plant. Advances in Geo-Energy Research, 2018, 2(2): 190-209, doi: 10.26804/ager.2018.02.0

Review of recent research on photovoltaic thermal solar collectors

Photovoltaic (PV) technology can be categorized as a mature technology but its performance with its elevating temperature has a negative effect and opens a new area of research which led to the introduction of photovoltaic thermal collector (PVTC) systems. PVTC systems integrate PV modules and solar thermal collectors in a single unit to derive energies from uninterruptible solar sources. This review article is limited to the design and development of the heat exchangers used in typical air and water-based PVTC system. Heat exchangers are used to improve the heat transfer from the back surface of the PV module, thereby improving its overall efficiency. The review shows that for air-based PVTC, the electrical efficiency with various types of heat exchangers lies in the range of 4-24%, whereas for water-based PVTC is 5.1-15.8%. The maximum thermal efficiency achieved for the water-based system is observed to be 72% against the 87% for the air-based system indicating that a significant approach has been made in the air-based system with the novel concept of the heat exchangers as compared to the water-based system. At the end of the paper, some future recommendations are also commented on to make the PVTC system more viable

The effect of plant growth regulators, explants and cultivars on spinach (Spinacia oleracea L.) tissue culture

Spinach (Spinacia oleracea L.) is an important vegetable crop of which dioecy in nature has made cultivar improvement difficult using traditional breeding methods; therefore, production of high amount of disease free spinach is critical. To achieve the best explants and media for spinach tissue culture, the effects of two different plant growth regulators, two explants and cultivars on adventitious shoot regeneration were tested. The Analysis of Variance (ANOVA) showed that the effects of plant growth regulators on spinach tissue culture were significant; moreover, the effects of explants were not significant except on the regeneration phase. The best medium for callous induction was MS media containing 1.5 mgl-1 IAA + 2.5 mgl-1 GA3. The best medium for shoot regeneration was MS media contained 0.5 mgl-1 NAA + 2 mgl-1 GA3. The best rooting medium was MS medium containing 0.5 mgl-1 IBA. Results presented inhibitory effect of GA3 for callus and root formation; whereas, promote shoot development

Energy, exergy and economic analyses of new coal-fired cogeneration hybrid plant with wind energy resource

© 2020 Elsevier Ltd A novel configuration of a coal-fired cogeneration plant is proposed in this paper. This novel system is composed of combustion chamber, Rankine cycle, absorption chiller, alkaline electrolyzer, and methanation plant. In the proposed configuration, the heat of exhaust gas from the combustion chamber can be used in a Rankine cycle to produce electricity. The heat of exhaust gas also powers the absorption chiller to provide cooling. The exhaust gas flows through a sulfur extraction unit to separate sulfur from CO2 gas. To supply electrical power, wind turbines alongside the Rankine cycle are considered. A part of the produced electricity from both the Rankine cycle and the wind turbines can be used by an alkaline electrolyzer to produce hydrogen and oxygen. The CO2 gas from sulfur unit and hydrogen gas (H2) provided by the electrolyzer can be delivered to a methanation unit to produce syngas (CH4) for different applications. The oxygen from the electrolyzer is injected into the combustion chamber to improve the combustion process. Results show that by using 80 units of 1 MW Nordic wind turbine to generate electricity, all of the CO2 in the exhaust gas is converted to syngas. The whole system energy and exergy efficiencies are equal to 16.6% and 16.2%. The highest and lowest energy efficiencies of 85% and 30.1% are related to compressor and steam power plants. The energy and exergy efficiencies of the wind turbine are 30.7% and 11.9%. The system can produce 40920.4 MWh of electricity and 180.5 MWh of cooling. As CO2 is consumed to produce syngas, the proposed system is capable of avoiding a significant amount of 2776 t CO2 emissions while producing 1009.4 t syngas annually. Based on economic analysis, the payback period of the system is 11.2 y, and internal rate of return is found to be 10%, which can prove the viability of the proposed configuration

Natural gas-fueled multigeneration for reducing environmental effects of brine and increasing product diversity: thermodynamic and economic analyses

Water scarcity threatens human life and it is likely to be a main concern in the next century. In this work, a novel multigeneration system (MGS) is introduced and assessed with energy, exergy, and economic analyses. This MGS includes a gas cycle, multieffect distillation, an absorption refrigeration cycle, a heat recovery steam generator, and electrodialysis. Electrodialysis is integrated into this configuration to produce sodium hydroxide and hydrogen chloride from brine to prevent its release to the environment with harmful impacts. The other products are electricity, cooling, and demineralized water. For the evaluation of the proposed system, one computer code is provided in engineering equation solver software. For physical properties calculation, the library of this software is used. The MGS produces 614.7 GWh of electrical energy, 87.44 GWh of cooling, 12.47 million m3 of demineralized water, and 0.092 and 0.084 billion kg of sodium hydroxide and hydrogen chloride over a year. Energy and exergy evaluations demonstrate that the MGS energy and exergy efficiencies are 31.3% and 18.7%, respectively. The highest and lowest value of exergy destruction rate is associated with the combustion chamber and pump, respectively. The economic evaluation indicates that the net present value of this proposed system is 3.8 billion US$, while the internal rate of return and payback period, respectively, are 0.49 and 2.1 years.Peer ReviewedPostprint (published version

Investigation the integration of heliostat solar receiver to gas and combined cycles by energy, exergy, and economic point of views

Due to the high amount of natural gas resources in Iran, the gas cycle as one of the main important power production system is used to produce electricity. The gas cycle has some disadvantages such as power consumption of air compressors, which is a major part of gas turbine electrical production and a considerable reduction in electrical power production by increasing the environment temperature due to a reduction in air density and constant volumetric airflow through a gas cycle. To overcome these weaknesses, several methods are applied such as cooling the inlet air of the system by different methods and integration heat recovery steam generator (HRSG) with the gas cycle. In this paper, using a heliostat solar receiver (HSR) in gas and combined cycles are investigated by energy, exergy, and economic analyses in Tehran city. The heliostat solar receiver is used to heat the pressurized exhaust air from the air compressor in gas and combined cycles. The key parameter of the three mentioned analyses was calculated and compared by writing computer code in MATLAB software. Results showed the use of HSR in gas and combined cycles increase the annual average energy efficiency from 28.4% and 48.5% to 44% and 76.5%, respectively. Additionally, for exergy efficiency, these increases are from 29.2% and 49.8% to 45.2% and 78.5%, respectively. However, from an economic point of view, adding the HRSG increases the payback period (PP) and it decreases the net present value (NPV) and internal rate of return (IRR)

Investigating Smart City Development Based on Green Buildings, Electrical Vehicles and Feasible Indicators

With a goal of achieving net-zero emissions by developing Smart Cities (SCs) and industrial decarbonization, there is a growing desire to decarbonize the renewable energy sector by accelerating green buildings (GBs) construction, electric vehicles (EVs), and ensuring long-term stability, with the expectation that emissions will need to be reduced by at least two thirds by 2035 and by at least 90% by 2050. Implementing GBs in urban areas and encouraging the use of EVs are cornerstones of transition towards SCs, and practical actions that governments can consider to help with improving the environment and develop SCs. This paper investigates different aspects of smart cities development and introduces new feasible indicators related to GBs and EVs in designing SCs, presenting existing barriers to smart cities development, and solutions to overcome them. The results demonstrate that feasible and achievable policies such as the development of the zero-energy, attention to design parameters, implementation of effective indicators for GBs and EVs, implementing strategies to reduce the cost of production of EVs whilst maintaining good quality standards, load management, and integrating EVs successfully into the electricity system, are important in smart cities development. Therefore, strategies to governments should consider the full dynamics and potential of socio-economic and climate change by implementing new energy policies on increasing investment in EVs, and GBs development by considering energy, energy, techno-economic, and environmental benefits

MULTI-OBJECTIVE PARTICLE SWARM OPTIMIZATION OF THE K-TYPE SHELL AND TUBE HEAT EXCHANGER (CASE STUDY)

This paper investigated optimization of two objectives function include the total amount of heat transfer between two mediums and the total cost of shell and tube heat exchanger. The study was carried out for k-type heat exchanger of the cryogenic unit of gas condensates by multiple objective particle swarm optimization. Six decision variables including pipe pitch ratio, pipe diameter, pipe number, pipe length, baffle cut ratio, and baffle distance ratio were taking into account to conduct this simulation-based research. The results of mathematical modeling confirmed the actual results (data collected from the evaporator unit of the Tehran refinery’s absorption chiller). The optimization results revealed that the two objective functions of heat transfer rate and the total cost were in contradiction with each other. The results of the sensitivity analysis showed that with change in the pitch ratio from 1.25 to 2, the amount of heat transfer was reduced from 420 to 390 kW about 7.8%. Moreover, these variations caused reduction in cost function from 24,500 to 23,500 $, less than 1$ to 24500$ about 22%. © 2021. All rights reserved

Design of a novel control algorithm for a 6 D.O.F. mobile manipulator based on a robust observer

In this paper a control algorithm based on a design technique named "Robust Damping Control" is introduced. A robust observer is further shown to overcome the problem of using velocity sensors that may degrade the system performance. The proposed controller uses only position measurements and is capable of disturbance rejection in the presence of unknown bounded disturbances without requiring the knowledge of its bound. Moreover, we propose an accurate and fast time integration method to solve the dynamic equations of the mobile manipulator system. The simulation results of a 6 D.O.F. mobile manipulator illustrate the effectiveness of the presented algorithm