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The choice of refrigerant and expander is always one of the main concerns of researchers using organic Rankine cycles. The problem of using the organic Rankine cycle becomes more complicated when there are two waste heat sources with different temperatures in a system, such as exhaust gas and jacket water heat sources in an internal combustion engine. Hence, in this paper, a thermoeconomic program is developed using four types of volumetric expanders, including piston, screw, scroll and root, and eight different organic fluids in the series double cascade-evaporator organic Rankine cycle. The studied organic fluids were selected to cover a wide range of pressure levels in the series double cascade-evaporator organic Rankine cycle, including R245 FA, R123, n-pentane, acetone, n-heptane, benzene, n-octane and toluene. In the present study, 16 different pairs of expanders were examined for a cohort of 8 dissimilar fluids, resulting in an aggregate of 128 distinctive cases. In each of the 128 different cases, the important parameters, including power production, exergetic efficiency, total investment cost, net present value and levelized cost of electricity generation, are calculated. Also, the Pareto method is used to select the best organic fluid and expander pair. The results show the fluids with lower critical temperatures performed better due to the pressure ratio limit. The lowest cost of the expander compared to the total cost was 4.98%, related to the pair of root–scroll expanders, and the highest cost of 48.21% was related to the piston–screw expander pair. The lowest total investment cost was 377,478$ for the n-pentane and the piston–scroll expander pair. The screw expander costs more than other expanders, especially when in the low-pressure cycle. According to the optimization results, the optimal pair of expanders for the series double cascade-evaporator organic Rankine cycle system is scroll–scroll with n-pentane as the working fluid. Additionally, the exergetic efficiency, payback period and total investment cost values in this case are 0.3945, 4.089 years and 385,786$, respectively. [ABSTRACT FROM AUTHOR]

Türkiye is the largest cement producer of Europe and the second biggest cement exporter in the world. The industry is responsible for more than 8% of global carbon dioxide (CO2) emissions and around 15% of the primary energy consumed worldwide. In this paper, the specific energy consumption (SEC) and related emissions of a real scale cement factory currently running in Türkiye have been decreased by investigating the effects of moisture rate of the raw materials and the hot gas transfer to the grinding unit. The data has been collected in the factory site by using the monitoring equipment and real time detection over a 24-month period. Energy and exergy destructions and exergetic cost distributions are determined by using specific exergy costing method (SPECO) for all units of the factory. The specific exergetic consumption (SExC) and production (MC) costs of raw meal are calculated to be 5.05 $/GJ and 4.13 $/ton, respectively. It is investigated that the hot gas supply to the grinding unit and decreasing the moisture rate of feeding materials decreased the SPECO of raw meal, clinker and cement by 8.25%, 5.49% and 4.89% respectively. The applications provide 184.69 MJ reduction in specific energy consumption (SEC) per ton of cement produced and blocked 75,343.37 tons of CO2 emissions per year and reduced the cement production cost to 40.47 $/ton corresponding to a saving of $2.06 M per year. It has been demonstrated that it is very important to keep the moisture content of raw materials used in the cement industry as low as possible in terms of reducing energy consumption and manufacturing costs for sustainable production. [ABSTRACT FROM AUTHOR]

Because of the fossil fuels crisis in recent years, increasing fossil fuel consumption and the oil crisis, energy efficiency is becoming a major concern of the twenty-first century. In this research, the combined cycle of steam Rankine and organic Rankine with the primary mover of the Allam generation cycle has been simulated. The hybrid cycle is configured in such a way that the high temperature waste heat first acts as the steam cycle evaporator and the waste heat output from the steam cycle evaporator is used as the low temperature evaporator of the organic cycle. Then, the effect of changing various parameters such as evaporator temperature and steam cycle condenser pressure on output work values, total irreversibility, energy efficiency, exergy efficiency and exergy-economic variables is investigated. The results show that the energy efficiency and exergy efficiency of the combined cycle are 0.57 and 0.66, respectively, and the amount of output work and total irreversibility are 150,125 kW and 91,237 kW, respectively. Also, according to the study results, a lot of exergy destruction takes place in the system, thus it is recommended to increase the initial price in different components in order to improve the performance of the system. Evaporators and steam cycle condensers are components that should be considered from an exergy-economic perspective, as they have the highest rate for the sum of the initial cost rate and the cost of exergy destruction. [ABSTRACT FROM AUTHOR]

Because of population growth, demands for water and energy for domestic, industrial, and agricultural usages are increasing. Considerable research has been conducted in recent years to evaluate the thermodynamics and optimization of desalination systems. One important concept is the capacity to integrate power generation systems with desalination plants. The purpose of this study is to analyze the exergy and thermoeconomics of the combined desalination system (MED) and Allam power generation system. The key advantage of this proposed system is to use the heat generated in the Allam power generation system to operate the desalination system. Similarly, due to the performance of the Allam generation system, the amount of carbon dioxide produced is virtually zero. By determining the processes and solving the governing equations, the properties of the fluids passing through the combined cycle of Allam and MED are determined and thermodynamic, exergetic and thermoeconomic analysis is performed along with the thermoeconomic optimization of the system. In this research, genetic algorithm has been used for optimization and the result has been described in multi-objective optimization. Subsequently, parametric analysis and the effect of design variables on the system cost function have been accomplished. The results show that in a specific vector of decision variables, the objective functions including, the exergetic efficiency and the cost of the product produced by the system are optimized simultaneously. In conventional desalination plants, a boiler is used to supply the steam entering the desalination system. After conducting the model simulation of the desalination system, the Allam generation system is modeled as well. Thus, by combining these two systems, the heat generated by the Allam generation system can be used to evaporate water in the desalination system. In the ideal case, the price of fresh water of using the steam produced by the boiler is $1.131 per cubic meter, and by means of the steam produced by the power generation system would be $1.087 per cubic meter. Hence, the results indicate that combining the desalination system with the Allam generation system provides a 4% reduction. Reducing carbon dioxide emissions is also a significant benefit of this system. [ABSTRACT FROM AUTHOR]

This work aims to enhance the energy cost-saving potential of conventional mud-brick by including natural waste materials as insulators. The solid waste materials considered for mud bricks are rice husk, sawdust, coir pith, and fly ash. This work investigates the structural and thermoeconomic performance of four types of insulated mud bricks and three roofs of ferrocement, clay, and ceramic materials. The thermal properties of walls and roofs were measured as per ASTM D 5334 standards. The utilization of solid waste in mud bricks enhanced the structural properties and air-conditioning cost-saving potential of the mud bricks. The results also showed the mitigation of greenhouse gas emissions with the usage of insulated bricks for buildings. The rice husk mud-brick wall showed better results of higher time lag, lower decrement factor, higher air-conditioning cost-savings, acceptable payback periods, and higher annual carbon mitigation values of 11.11 h, 0.24, 1.74 $/m2, 1.17 years, and 33.35 kg/kWh, respectively, among all the studied multilayer walls. Among the roofs, clay tile roof showed a lower decrement factor (0.989), higher time lag (0.73 h), higher air-conditioning cost-savings (2.58 $/m2), lower payback periods (0.61 years), and higher annual carbon mitigation (21.73 kg/kWh). The results are in designing eco-friendly and energy-efficient envelopes for buildings. [ABSTRACT FROM AUTHOR]

An approach for evaluating heat-exchanger operating efficiency using the calculated exergy efficiency (EE) that allows heat-exchanger system elements with low heat-transfer efficiency to be located and their maintenance (cleaning) to be managed according to their condition was proposed. Measurements required for the EE calculation were recorded automatically from the Automatic Process Control System databases of the application. Real-time mathematical modeling of the current mode of the facility using a computer training complex provided additional data. [ABSTRACT FROM AUTHOR]

Performance optimization of a single-effect lithium bromide water absorption refrigeration system is the subject of this paper. First, the thermodynamic model of the system wasderived based on the first and second law analysis of an absorption refrigeration cycle with LiBr-water as the working fluid pair. Then, the effects of different design parameters such as the generator inlet hot water temperature, evaporator inlet chilling water temperature and absorber and condenser inlet cooling water temperatures on the performance of the systemwere investigated. In order that, by defining the coefficient of performance (COP), exergy efficiency (Second-law efficiency) and total cost function of the system as the objective functions, the genetic algorithm optimization technique was implemented to evaluate these performance indexes. Finally, the optimal values of design parameters and objective functions were found and compared to the initial values. Results show significant improvement in system COP (about 75 %), exergy efficiency (47 %) and total cost (12 %). [ABSTRACT FROM AUTHOR]