Sharif Digital Repository

This paper presents a theoretical framework for the energy and exergy evaluation of a basic as well as three modified Organic Rankine Cycles (ORCs). The modified ORCs considered incorporating turbine bleeding, regeneration and both of them. The results demonstrate that evaporator has major contribution in the exergy destruction which is improved by increase in its pressure. The results confirm that the integrated ORC with turbine bleeding and regeneration has the highest thermal and exergy efficiencies (22.8% and 35.5%) and the lowest exergy loss (42.2 kW) due to decrease in cold utility demand and high power generation  

4E analysis is used on a Brayton-Rankine combined cycle power plant (CCPP) with a dual pressure heat recovery steam generation (HRSG) system. A multi-objective genetic-based evolutionary optimization has been used to estimate the most optimal exergy efficiency status, exergy cost reduction, carbon emission reduction, and NOx emission reduction. For the validation of the data, the simulation results are compared with the plant's data. This study investigates the effect of every decisive parameter on the objective performance parameters of the CCPP. The primary estimated results are the emission rates, efficiencies, and the exergoeconomic cost of the system. At the optimum operational state,... 

Traditionally energy systems were analyzed technically, but current environmental issues and considerations have put new constraints on the planning and managing of energy systems. Such an exergoeconomic and exergoenvironmental analysis were born. This analysis is aimed to describe the necessity and application of a new concept in environmental liability accounting based on physical quantities to overcome the weaknesses of the developed allocation methods and the internalization of external environmental damages. The proposed method is modified in environmental analysis to consider the effect of non-energy flows on a macro-surface energy system. As a case study, this method is tuned for a... 

In this study, energy, exergy, and exergoeconomic analysis is performed on the recent trend of joint production of liquefied natural gas and natural gas liquids based on mixed fluid cascade most important of refrigeration systems. The proposed process is first simulated and exergticly analyzed, and finally, an economic model is used to analyze the exergoeconomic performance. The results include the cost of exergy destruction, exergoeconomic factors, and exergy efficiency. The exergy analysis results show that the proposed process's exergy efficiency is about 53.84%, and the destruction rate is 42618 kW with LNG and NGL production rates of 69.00 kg/s and 27.42 kg/s, respectively. Also,... 

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... 

The gas turbine (GT) is known to feature low capital cost to power ratio, high flexibility, high reliability without complexity, short delivery time, early commissioning and commercial operation and fast starting-accelerating. Hence, researchers all over the world are working to increase the output power and efficiency of gas turbine cycle. One of the important techniques to increase the output power of such cycles is the compressor inlet air cooling method. The objective of this paper is to analysis the gas turbine cycle from both energy and exergy point of view. Thus, two important methods for increasing the output power, i.e. fog and media inlet air cooling systems are discussed.... 

A new combined cooling and power (CCP) cycle is proposed by a novel combination of the Kalina cycle (KC) and ejector refrigeration cycle (ERC) to produce simultaneous power output and cooling output. The exhaust of the turbine is fed to the ejector as a primary flow to draw the secondary flow (outlet of the evaporator) into the ejector. Energy, exergy, and exergoeconomic analysis of the proposed cycle are carried out leading to determine the first-law-efficiency, the second-law-efficiency, the sum unit cost of the product (SUCP) of the system, and the main source of the irreversibility. The thermal efficiency, exergy efficiency, overall exergy destruction rate, SUCP of the system, net... 

The use of solar collectors in combination with heat pipes is rapidly growing in recent years. Heat pipes, as heat transfer components, have undeniable advantages in comparison with other alternatives. The most important advantage is their high rate of heat transfer at minor temperature differences. Although there have been numerous studies on the heat analysis or first thermodynamic analysis of flat plate solar collectors in combination with heat pipes, the exergy analysis of these collectors is needed to be investigated. In this work, energy and exergy analysis of a flat plate solar collector with a heat pipe is conducted theoretically. Next, the exergy efficiency of pulsating heat pipe... 

An attempt is made to utilize exhaust gases of a small gas turbine in augmenting power output through the employment of a thermoacoustic system. It is assumed that the thermoacoustic system is powered only by the waste heat of the gas turbine. A comprehensive cycle analysis of the integrated gas turbine thermoacoustic engine "IGTTE" is carried out from energy and exergy point of view. Results indicate the thermodynamic advantages of the IGTTE