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In the present paper second law analysis of crossflow heat exchangers has been carried out in the presence of non-uniformity of flow. This non-uniformity is modeled with the help of axial dispersion model and takes into account the back mixing and flow maldistribution. An analytical model for exergy destruction has been evaluated for the cross-flow configuration. A wide range of study of the operating...
Deaerator is an essential open feed water heater in the steam bottoming cycle to improve the efficiency and also to remove the dissolved gasses from the feed water. Heat recovery steam generator (HRSG) plays a key role on the performance of the combined cycle (CC). In this work, attention has been focused to improve the performance of a triple pressure (TP) CC with a deaerator location. In this work,...
In the distributed power generation market, Solid Oxide Fuel Cell–Gas Turbine (SOFC–GT) hybrids are an attractive option. Prototypes are being tested around the world with different types of fuel, but mainly natural gas. In this publication, a study of SOFC–GT hybrids for operation with liquid fuels is presented. Two liquid fuels were investigated, methanol and kerosene, in four layouts, taking into...
Column grand composite curves and the exergy loss profiles produced by the Column-Targeting Tool of the Aspen Plus simulator are used to assess the performance of the existing distillation columns, and reduce the costs of operation by appropriate retrofits in a biodiesel production plant. Effectiveness of the retrofits is assessed by means of thermodynamics and economic improvements. We have considered...
Production of methyl dodecanoate (biodiesel) using lauric acid and methanol with a solid acid catalyst of sulfated zirconia is studied by using two distillation sequences. In the first sequence, the methanol recovery column follows the reactive distillation column. In the second sequence, the reactive distillation and methanol recovery columns are thermally coupled. Thermally coupled distillation...
The industrial waste heat parameters, like flow rate and temperature, usually fluctuate in a certain range due to the variation of upstream industrial process. However, the heat recovery systems are usually designed not under the fluctuation range but under a specific point, therefore, the most reasonable design condition of the waste heat should be estimated based on the fluctuation ranges. A single...
A novel rotary desiccant cooling cycle is proposed and studied using thermodynamic analysis method. The proposed cycle integrates the technologies of isothermal dehumidification and regenerative evaporative cooling, which are beneficial for irreversibility reduction. Thermodynamic investigation on the basic rotary desiccant cooling cycle shows that the exergy efficiency of the basic cycle is only...
This work presents the simulated equilibrium compositions of ethanol steam reforming (SR), partial oxidation (POX) and auto-thermal reforming (ATR) at a large temperature range, steam-to-ethanol and oxygen-to-ethanol molar ratios. The simulation work shows that the moles of hydrogen yield per mole ethanol are of this order: SR > ATR > POX. The results are compared with other simulation works...
In order to investigate the Stirling engine implementation technology, a Solo Stirling Engine V161 cogeneration module has been installed at the Laboratory of Applied Thermodynamics of National Technical University of Athens. A special thermodynamic analysis of the engine's performance has been conducted introducing and utilizing specially designed computing codes along with the thermal balance study...
Organic Rankine cycle can effectively recover the low grade heat source due to its distinctive thermodynamic performance. Based on the thermodynamic mathematical models of an ORC (organic Rankine cycle) system, this study examines the effects of key thermodynamic design parameters, including turbine inlet pressure, turbine inlet temperature, pinch temperature difference and approach temperature difference...
The thermodynamic analysis and the coupling and optimization between chemical synthesis and power generation in a polygeneration system are presented. Unlike full conversion of syngas into chemicals in the traditional SNG (synthetic natural gas) production system, by moderate conversion the sharp increase in energy consumption for SNG synthesis can be avoided in the new system. Also, by recovering...
An original model for thermodynamic analysis of a batch type fluidized bed dryer is proposed herein considering two separate systems comprised of drying air medium as a control volume and particles to be dried as a control mass. By means of the proposed model, energetic and exergetic analyses of a drying column of a batch type fluidized bed dryer are carried out as an original contribution to literature...
Due to the intermittent nature of the solar radiation, the day-long continuous production of cold is a challenge for solar-driven adsorption cooling systems. In the present study, a developed solar-powered adsorption cooling system is introduced. The proposed system is able to produce cold continuously along the 24-h of the day. The theoretical thermodynamic operating cycle of the system is based...
An IGCC (integrated gasification combined cycle) is a widely used electrical power generation system that allows for a variety of feedstocks with high efficiencies. In this study, a 300 MW class IGCC plant was simulated using the PRO/II software package, and thermodynamic analysis was performed. The simulated results were compared to the basic design data for a 300 MW Class IGCC demonstration plant...
This paper analyzes the possibility and the cost of using gas from biomass gasification in the production of electricity and generation of heat using a piston engine in which the power in the supplied biomass is no more than 50 MW. A mathematical model that allows for thermodynamic and economic analysis was designed. The input data regarding the gas generator and the process gas were collected in...
Low-grade waste heat source accounts for a large part of the total industrial waste heat, which cannot be efficiently recovered. The ORC (Organic Rankine Cycle) system has been proved to be a promising solution for the utilization of low-grade heat sources. It is evident that there might be several waste heat sources distributing in different temperature levels in one industry unit, and the entire...
This study is to advance the energy performance of solar air-conditioning system through appropriate component integration from the absorption refrigeration cycle and proper high-temperature cooling. In the previous studies, the solar absorption air-conditioning using the working pair of water – lithium bromide (H2O–LiBr) is found to have prominent primary energy saving than the conventional compression...
Double reheat steam systems have been receiving more attention because of the rapid development of ultra-supercritical power plants. In this study, the thermodynamic analysis and design optimization of a double reheat system in an ultra-supercritical power plant are comprehensively conducted. Besides, thermodynamics calculation, as well as exergy and techno-economic analyses are conducted to reveal...
For high temperature ORC (Organic Rankine Cycle) used in engine waste heat recovery, it's very critical to select a high temperature working fluid. HCs (Hydrocarbons) usually have excellent cycle performance, but the flammability limits their practical application. Considering that some retardants can be used to suppress flammability, the paper presents an application of mixtures based on hydrocarbons...
The aim of this work is to provide an upper estimate of the theoretical maximum specific thrust of the hydrocarbon fueled scramjet. An idealized thermodynamic cycle analysis is carried out to evaluate the performance of scramjet engines at different flight conditions, inlet pressure ratio and fuel equivalence ratio. Contrary to known Brayton cycles for the gas-turbine and ramjet engine, the inherent...
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