On the basis of the exergy analysis, a performance optimization is carried out for a generalized irreversible refrigerator model, which takes into account the heat resistance, heat leakage and internal irreversibility losses. A new ecological criterion, named coefficient of performance of exergy (COPE), defined as the dimensionless ratio of the exergy output rate to the exergy loss rate, is pro...

Cascaded thermal storage, consisting of multiple Phase Change Materials (PCMs) with different melting temperatures, has been proposed to solve the problem of poor heat transfer caused by unavoidable decrease of temperature differences during heat exchange process. This paper conducts a theoretical study of the overall thermal performance for a cascaded thermal storage system. Both heat transfer...

In this paper, a comparison of exergetic models between two hot air engines (a Gamma type Stirling prototype having a maximum output mechanical power of 500 W and an Ericsson hot air engine with a maximum power of 300 W) is made. Referring to previous energetic analyses, exergetic models are set up in order to quantify the exergy destruction and efficiencies in each type of engine. The repartit...

since knowledge on hydrodynamic torque of a butterfly valve is very important for butterfly valve design, its hydrodynamic torque is investigated in this paper. in reality, the investigation of the loss coefficient and torque from some experiments will take a long time and a lot of money. this paper presents a statistical study of the flow past the butterfly valve in a static analysis using com...

exergy analysis and response surface methodology (rsm) is applied to reduce the exergy loss and improve energy and exergy efficiency of acetic acid production plant. exergy analysis is run as a thermodynamic tool to assess exergy loss in reactor and towers of acetic acid production process. the process is simulated in aspen plus(v.8.4) simulator and the necessary thermodynamics data for calcula...

A thermodynamic model of a compartment fire with one state variable (corresponding to the dimensionless temperature of the smoke layer) based on energy conservation is studied from the point of view of the Second Law (exergy analysis). To define the exergy rate of the process, a novel concept of mean thermodynamic temperature is introduced for the smoke layer. This parameter is the equivalent o...

This study proposes the concept of the local heat loss coefficient and examines the calculation method for the average heat loss coefficient and the average absorber plate temperature. It also presents an exergy analysis model of flat plate collectors, considering non-uniformity in temperature distribution along the absorber plate. The computation results agree well with experimental data. The ...

Cogeneration may be defined as a system which contains electricity production and regain of the thermo value of exhaust gases simultaneously. The examination is based on the data’s of an active cogeneration plant. This study, it is aimed to determine which component of the system should be revised first to raise the efficiency and decrease the loss of exergy. For this purpose, second law analys...

in this study, the performance of an irreversible regenerative brayton cycle is sought through power maximizations using finite-time thermodynamic concept in finite-size components. optimizations are performed using a genetic algorithm. in order to take into account the finite-time and finite-size concepts in the current problem, a dimensionless mass-flow rate parameter is used to deploy time v...