Exergy efficiency calculation of energy intensive systems

Nikulshin, Vladimir; Chen, Wu; Nikulshina, V.

doi:10.1016/s1164-0235(01)00042-5

Cited by 27 publications

(19 citation statements)

References 6 publications

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“…But seeking better method which helps to recover even part of energy paid for liquefying of natural gas, the exergy efficiency of hypothetical conversion LNG to ANG should be considered. It is found at [6] that exergy efficiency is defined as ratio of used exergy over available one: In first approximation, treating ANG filling system as quasi-continuous with exergy losses due to finite temperature difference only, exergy efficiency formula can be written: where: e LNG -exergy of LNG, e NG -exergy of natural gas (vaporized LNG) 1 atm, 111 K, ∆e heat transfer -exergy losses due to heat transfer Using this formula the exergy efficiency of combined LNG -ANG system can be calculated as a function of the ratio of mass vaporized/ mass adsorbed (FIGURE 7). It can be observed that there is a maximum of the efficiency of 0.47 for the ratio gas stored/ regasified of about 4.…”

Section: Discussionmentioning

confidence: 97%

Liquid natural gas regasification combined with adsorbed natural gas filling system.

Roszak¹,

Chorowski²

2012

AIP Conference Proceedings

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The article provides an introduction to innovative method of Liquid Natural Gas (LNG) physical exergy practical utilization. The energy spent to liquefy natural gas (a thermodynamic minimum is about 0.13 kWh/l of LNG depending on pressure and chemical composition) can be partly recovered in the system making use either of the LNG low temperature (111 K) or its ability to increase the pressure in a storage vessel by heat absorption from the environment. The paper presents estimation of the LNG physical exergy and its dependence on the pressure and temperature. Then description and comparison of available natural gas storage methods (liquefaction, compression, adsorption) is given, with a special attention paid to Adsorbed Natural Gas (ANG) technology. Original data concerning adsorption isotherms of methane with activated carbon MaxsorbIII are presented. A concept of ANG storage technology coupled with the LNG regasification, is a promising technique of utilization of the LNG cold exergy. The energy efficient combination of ANG with LNG may help market progress of adsorption technology in natural gas storage and distribution. The ANG/LNG coupling is especially perspective in case of small capacity and distributed natural gas deposits exploitation.

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Section: Discussionmentioning

confidence: 97%

Liquid natural gas regasification combined with adsorbed natural gas filling system.

Roszak¹,

Chorowski²

2012

AIP Conference Proceedings

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“…And chemical exergy for organic substance is defined as follow: The analysis used the topological approach where each element is mapped and the exergy of its nodes at the interconnection is calculated [21,22]. This study focuses on the overall system which looks at the overall exergy loss and exergy efficiency.…”

Section: Exergy Analysismentioning

confidence: 99%

Exergy Analysis of Organic Rankine Cycle and Electric Turbo Compounding for Waste Heat Recovery

Muhammad

Mamat

Salim

2018

IJET

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With such tough legislation on current emission standards, car manufacturers are focusing on increasing the efficiency of their engines with the development of advance waste heat recover (WHR) technology. Organic Rankine Cycle (ORC) and Electric Turbo Compounding (ETC) system have a good potential to be used as exhaust energy recovery. This paper compares the exergy availability and losses between the ORC and the ETC. In this particular study, exhaust data from the Proton 1.6L CamPro CFE turbocharged engine was used. This particular engine already has a main turbocharger, making the added WHR as a secondary recovery system to further increase the engine efficiency. Both systems are coupled to a 1 kW electric generator for ease of comparisons. At first the available exer gy is calculated for both WHR technologies. Exergy losses from rotating the generator are analysed to finally determine the thermal effi ciency of the overall system. Exergy calculation is simplified to only account for chemical and physical exergy since kinetic and potential energy are negligible in comparison. Available exergy for ORC was significantly high which went up to 12.5 kW with the exergy losses recorded at 9.7 kW. The ETC achieved only 5 kW but had a small loss at 8x10-3 kW. Average thermal efficiency of the ORC systems was 10.7% compared to ETC which was 58.7%. It can be concluded that the complexity of the ORC system contributes to its downfall where multiple components increase its exergy losses compared to the simplistic design of an ETC.

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“…In one approach, the system is assumed as a black box and exergy efficiency is calculated as the ratio of total exergy of useful product to the total exergy input [11,37]. In another approach, the role of individual unit operations in total exergy efficiency of the integrated system is determined [38,39] which is used in this study. Based on this approach, the overall exergy efficiency of the system is calculated from the following equation:…”

Section: Energy and Exergy Efficiencies Of An Integrated Systemmentioning

confidence: 99%

“…Based on the process flow diagram shown in Figure 1 and the classification of unit operations reported in [38], the useful and available exergy of each unit operation is listed in Table 2. The following equation for total exergy efficiency of the system is achieved from Equation (25) and relations presented in Table 2: (27) where Ex ch,pg , Ex ch , biom and Ex ch , fuel , MJ/kg, are the chemical exergy of producer gas, biomass and excessive fuel, respectively.…”

Section: Energy and Exergy Efficiencies Of An Integrated Systemmentioning

confidence: 99%

Analysis of Operation Parameters in a Dual Fluidized Bed Biomass Gasifier Integrated with a Biomass Rotary Dryer: Development and Application of a System Model

Puadian

Pang

2014

Energies

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An integrated system model was developed in UniSim Design for a dual fluidized bed (DFB) biomass gasifier and a rotary biomass dryer using a combination of user-defined and built-in unit operations. A quasi-equilibrium model was used for modelling biomass steam gasification in the DFB gasifier. The biomass drying was simulated with consideration of mass and energy balances, heat transfer, and dryer's configuration. After validation using experimental data, the developed system model was applied to investigate: (1) the effects of gasification temperature and steam to biomass (S/B) ratio on the gasification performance; (2) the effect of air supplied to the fast fluidized bed (FFB) reactor and feed biomass moisture content on the integrated system performance, energy and exergy efficiencies. It was found that gasification temperature and S/B ratio have positive effects on the gasification yields; a H 2 /CO ratio of 1.9 can be achieved at the gasification temperature of 850 °C with a S/B ratio of 1.2. Consumption of excessive fuel in the system at higher biomass feed moisture content can be compensated by the heat recovery such as steam generation while it has adverse impact on exergy efficiency of the system.

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Exergy efficiency calculation of energy intensive systems

Cited by 27 publications

References 6 publications

Liquid natural gas regasification combined with adsorbed natural gas filling system.

Liquid natural gas regasification combined with adsorbed natural gas filling system.

Exergy Analysis of Organic Rankine Cycle and Electric Turbo Compounding for Waste Heat Recovery

Analysis of Operation Parameters in a Dual Fluidized Bed Biomass Gasifier Integrated with a Biomass Rotary Dryer: Development and Application of a System Model

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