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...

The second law of thermodynamics and, specifically, exergy analysis have been traditionally used for the assessment and optimization of energy systems. Nevertheless, as shown in this paper, exergy could also constitute a powerful tool for the evaluation of mineral commodities. That said, new or re-defined exergy-based concepts need to be developed. This paper presents Thanatia as a baseline for...

A single vacuum tube based solar cooker has high energy and exergy efficiency, and is capable of achieving cooking temperatures as high as 250 C. The reason for high energy and exergy efficiencies of this solar cooker is the high achievable concentration ratios of 15e20, which are not possible with multiple vacuum tube based solar cookers. In this paper, a comparative study has been carried out...

Exergy is an effective, single measurement to express the information level of communities, while the trends of community dynamics are difficult to represent since communities consist of different species varying in a complex manner. Using the data concerning benthic macroinvertebrate communities collected from streams, we implemented artificial neural networks in patterning and predicting exer...

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 recent work is dedicated to the study of behaviour of exergy and structural exergy in physical models of aquatic ecosystems—mesocosms and microcosms and in Lake Baikal. The results of field experiments with mesocosms on Lake Baikal, containing natural plankton assemblage, and laboratory experiments with microcosms containing Daphnia magna and Chlorella vulgaris demonstrated decrease of the ...

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...

The concept of exergy is defined and applied to district heating systems. The influence from different reference state conditions and system boundaries are explained in some detail. The aim is to show the simplicity and value of using the concept of exergy when analyzing district heating processes. The exergy factor is introduced and applied for a number of Swedish and Danish district heating s...

District heating has been available in Sweden since the 1950s and used more than half of the total energy use in dwelling and no-residential premises in 2013. Energy and exergy efficient conversion and energy resources are key factors to reduce the environmental impact. It is important to understand energy and exergy flows from both the supply and demand sides. The exergy method is also a usefu...

Preliminary note This paper presents the exergy destruction of an evaporator or a condenser or evaporator and condenser. The exergy destruction can be analytically calculated by using the same non-dimensional variables which have been used by its energy analysis. The one additional variable is the ratio of absolute input temperatures of both streams. This means that the given model enables the ...