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 ...

the purpose of this paper is multi-objective optimization of refrigeration cycle by optimization of all components of the cycle contains heat exchangers, air condenser, evaporator and super-heater. studied refrigeration cycle is compression refrigeration cycle of unit 132 third refineries in south pars that provide chilled water for cooling refinery equipment's. cycle will be performed by ...

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...

Two power plant schemes that reduce CO2 emission and employ natural gas reforming were analyzed and discussed. The first one integrates natural gas reforming technology for efficiency improvement with an oxy-fuel combined power system (OXYF-REF), with water as the main work fluid. The reforming heat is obtained from the available turbine exhaust heat, and the produced syngas is used as fuel wit...

This paper proposes a polygeneration system based on a multi-input chemical looping combustion system, which generates methanol and electricity, through the use of natural gas and coal. In this system, the chemical looping hydrogen (CLH) production system and the coal-based methanol production system are integrated. A high quality fuel, natural gas, is used to improve the conversion ratio of co...

To maximize the system-level heat integration, three retrofit concepts of waste heat recovery via organic Rankine cycle (ORC), in-depth boiler-turbine integration, and coupling of both are proposed, analyzed and comprehensively compared in terms of thermodynamic and economic performances. For thermodynamic analysis, exergy analysis is employed with grand composite curves illustrated to identify...

In the present study, thermo-economic analysis of a combined solid oxide fuel cell (SOFC) with a gas turbine, a generator-absorber heat exchanger (GAX) and heating process heat exchanger for heating, cooling and power production as a tri-generation system is conducted. Also, an external steam reformer is applied to convert methanol as oxygenated fuel to hydrogen for the electrochemical process ...