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In order to evaluate and improve the performance of a ground-coupled heat pump (GCHP) heating system with radiant floors as terminals, an exergy analysis based on test results is performed in this study. The system is divided into four subsystems, and the exergy loss and exergy efficiency of each subsystem are calculated using the expressions derived based on exergy balance equations. The avera...

Since the eco-efficiencies of all industrial processes/plants have become more and more important, engineers need to find a way to integrate control loop configuration and measurements of eco-efficiency. A new measure of ecoefficiency for control loop configuration was developed, the exergy efficiency factor. The exergy efficiency factor is based on the thermodynamic concept of exergy which can...

This study presents an experimental comparison of energy, exergy flow and second law efficiency of R22 and its substitute R436b (hydrocarbon mixture of 52% of propane (R290) 48% of isobutene (R600a)), vapour compression refrigeration cycles. The vapour compression refrigeration cycle was initially designed to operate with R22. The primary objective of this paper is to analyze the system process...

In this paper, performance analysis of a hybrid photovoltaic-thermal (PV/T) greenhouse air heater and dryer has been carried out. Analytical expressions have been developed for • greenhouse air temperature, instantaneous and overall energy and exergy efficiencies for without load and • instantaneous exergy efficiency with load under forced mode operation. An experimental validation has been car...

Exergy is precious energy. On the basis of thermodynamic analysis of thermal processes, one can choose more exergy-saving devices. This is especially important in refrigeration processes, in which the consumption of energy and exergy increases considerably with the falling cooling temperature. The exergy efficiency in terms of exergy losses of vapour compression and sorption cooling processes i...

Usually efficiency is defined in energetic terms without taking into account the quality of the energy. Another way to analyse and optimise processes and systems is in terms of exergy. The concept of exergy incorporates both qualitative and quantitative properties of energy. Exergy analysis makes the exact determination of the energetic and resource saving potential of industrial processes or s...

In this work, energy and exergy analyses are carried out for a combined cycle consisting of an organic Rankine cycle (ORC) and a liquefied natural gas (LNG) Rankine cycle for the recovery of low-grade heat sources and LNG cold energy. The effects of the turbine inlet pressure and the working fluid on the system performance are theoretically investigated. A modified temperature-enthalpy diagram ...

The performance and design criteria of air powered multistage turbines are studied thermodynamically in this paper. In-house code is developed in the C++ environment and the characteristics of four-stage turbines with inter-heating are analyzed in terms of maximum thermal efficiency, maximum exergy efficiency and maximum work output over the inlet temperature range of 293 K–793 K with inlet pre...

In this paper, an attempt has been made to obtain nonsensitive solutions in the multi-objective optimization of a photovoltaic/thermal (PV/T) air collector. The selected objective functions are overall energy efficiency and exergy efficiency. Improved thermal, electrical and exergy models are used to calculate the thermal and electrical parameters, overall energy efficiency, exergy components a...