Sharif Digital Repository

The behaviour of an industrial refrigeration cycle with refrigerant propane has been investigated by the exergy method. An natural gas liquid recovery unit with its refrigeration cycle has been simulated to prepare the exergy analysis. Using a typical actual work input value; the exergetic efficiency of the refrigeration cycle is determined to be 26.51 % indicating a great potential for improvements. The obtained simulation results reveal that the exergetic efficiencies of the air cooler(s) and chilling sections get the lowest rank among the other compartments of refrigeration cycle. Refrigeration calculations have been carried out through the analysis of T-S and P-H diagrams where... 

A considerable amount of energy is lost in the parabolic trough solar collectors due to the poor capability of working fluid in full absorption of the concentrated solar irradiation across the receiver tube. A new hybrid method is recommended here to cover up such deficiency by simultaneously using a rotary absorber tube and magnetic field inducer with nanofluid. Results showed that the combination effects of the receiver rotation and the magnetic field improve the convection mechanism in the absorber and increase both energetic and exergetic performance of the collector. The study reveals that there is an optimal rotational speed in the each magnetic field intensity for different... 

In this article, an attempt is made to utilize the exhaust gases of a small gas turbine to augment power output through the employment of a thermoacoustic system. A simple gas turbine cycle is selected as the base cycle and it is assumed that the thermoacoustic system is powered only by the waste heat of the base gas turbine. A comprehensive cycle analysis of the integrated gas turbine thermoacoustic engine (IGTTE) is carried out from an energy and exergy point of view. Exergy efficiency and internal exergy efficiency are calculated for the different components of the base gas turbine engine as well as the IGTTE. Value and exergy flow diagrams are used to investigate the possible... 

This paper shows a new possible way with particle swarm optimisation (PSO) to achieve an exergoeconomic optimisation of combinedcycle power plants. The optimisation has been done using a classic exergoeconomic and genetic algorithm, and the effects of using three methods are investigated and compared. The design data of an existing plant is used for the present analysis. Two different objective functions are proposed: One minimises the total cost of production per unit of output, and maximises the total exergetic efficiency. The analysis shows that the total cost of production per unit of output is 2%, 3%and 5% lower and exergy efficiency is 4%, 8% and 6% higher with respect to the base case... 

The objective of the research done in this paper was to determine cost of the power and heat system with pressurized fluidized bed gasifier using exergoexonomic appraisal techniques. Exergetic efficiency maximization was approached with use of multi-objective evolutionary optimization methods which were designed such that the costs were minimized in line with the exergoeconomic plans. The results of this method were also compared to methods that employ iterative techniques. Results showed an almost 12.28% improvement in exergetic efficient that the system could reach through utilization of the multi-objective evolutionary algorithm  

Gasification of black liquor is an alternative recovery technology. Pulp and paper industries are turning their attention to black liquor gasification as a replacement for recovery boilers. Gasification-combined cycle exergoeconomic analyses have been used to study the economical and exergetical performance of black liquor. Both conventional iterative exergoeconomic optimization and multi objective evolutionary optimization have been applied. The iterative optimization results have been compared with evolutionary programming results in order to evaluate the accuracy. The strength of proposed optimization methods are elucidated in a case study applied to Mazandaran Wood and Paper Industries... 

'Three-link-model' Exergoeconomic methodology optimises the design and operability of a system. Contrary to traditional iterative Exergoeconomic optimisation methods, a reversed method is used, since assumptions considered by Tsatsaronis for calculating cost-optimal Exergetic efficiency and relative cost difference, were not applicable, new assumptions have been adopted. In a case study applied to Mazandaran paper industry, iterative reversed optimisation results have been compared with evolutionary programming results. Replacement of Pressure Valve and Direct Cyclone Contact Evaporation is proposed, while by selection of the optimum decision variable, recoverable black liquor is increased... 

This paper conducts research on Thermodynamic modeling of the Fluidized bed Gasification and Exergoeconomic evaluation to determine the total cost of a combined heat and power system with pressurized fluidized bed gasifier. The paper presents use of multi-objective evolutionary optimization for the system's total cost minimization and Exergetic efficiency maximization, and has been compared to conventional iterative optimization method. It shows that by evaluating with conventional iterative optimization, Exergetic efficiency of total system can reach to 56.09% while using multi-objective evolutionary optimization it is 53.32%. However the product cost achieved by evolutionary optimization... 

Bi-evaporator electricity/cooling cogeneration systems can be a favorable addition to the integrated power plants since the generated cooling load should be addressed for different demands. More consequentially, taking advantage of such an integral set-up operated with highly reliable heat source such as biogas can be appreciable for nowadays industries. Regarding this demand, an innovative bi-evaporator electricity/cooling cogeneration system is introduced at first. Next, the suggested system is integrated with a gas turbine cycle fueled by biogas. In the subsequent part, the plausibility of the introduced integrated power plant is examined from first and second laws of thermodynamics (as... 

A considerable amount of energy is lost in the parabolic trough solar collectors due to the poor capability of working fluid in full absorption of the concentrated solar irradiation across the receiver tube. A new hybrid method is recommended here to cover up such deficiency by simultaneously using a rotary absorber tube and magnetic field inducer with nanofluid. Results showed that the combination effects of the receiver rotation and the magnetic field improve the convection mechanism in the absorber and increase both energetic and exergetic performance of the collector. The study reveals that there is an optimal rotational speed in the each magnetic field intensity for different... 

In advanced combined-cycle power plants, significant improvements in the thermodynamic performance are mainly achieved by the development of more efficient gas-turbine systems. This paper evaluates the effect of selected decision variables in the steam system for optimization of Thermal Combined Cycle Gas Turbine (TCCGT) power plant using an iterative exergoeconomic. The design variables were the thermodynamic parameters that establish the configuration both of the steam and gas systems. The design data of an existing plant (Damavand power plant in Tehran-Iran) is used. Two different objective functions are proposed: one minimizes the total cost of production per unit of output, and the... 

By simultaneously applying pinch technology and the exergoeconomic method to a complex process system, beneficial and energy-efficient measures are identified. The "three-link-model" exergoeconomic methodology optimizes the design and operability of a system. In this work, contrary to traditional exergoeconomic methods, a reversed method is used. The approach proposed for the optimization of such a complex system is to iteratively optimize subsystems. Since the reversed exergoeconomic method is used, assumptions considered by Tsatsaronis (based on four assumptions for calculating the cost-optimal exergetic efficiency and relative cost difference) are not applicable and new assumptions are to...