Performance analysis of gas liquefaction cycles

112

SUMMARY In this paper, five conventional LNG processes were investigated by energy and exergy analysis methods. On the basis of the energy analysis, three‐stage process of Linde AG and Stat oil (mixed fluid cascade [MFC]) has less energy consumption than the other ones (0.254 kWh/kg liquefied natural gas). Also, coefficient of performance of the cycles of this process is higher compared with the other ones. Exergy analysis results showed that the maximum exergy efficiency is related to the MFC process (51.82%). However, performance of the MFC process in terms of quality and quantity of energy consumption is considerable. But using three cycles in this process needs more components and consequently more fixed costs. In this study, sensitivity of coefficient of performance, specific energy consumption, and indexes of exergy analysis were also analyzed versus important operating variables for all cases. Copyright © 2014 John Wiley & Sons, Ltd.

Section: Introductionmentioning

confidence: 99%

“…Energy and exergy analyses of some power plants were carried out in [28][29][30]. Performance analysis of gas liquefaction cycles was considered by Kanoglu et al [31]. Mafi et al [32] compared two sets of low temperature mixed refrigeration cycles used for olefin plants.…”

Section: Introductionmentioning

confidence: 99%

Energy and exergy analyses of five conventional liquefied natural gas processes

Vatani

Mehrpooya

Palizdar

2014

112

“…Also, there have been several studies on the energy and exergy analysis of refrigeration systems used in liquefaction and separation of gases processed. Kanoglu et al [15] developed relations based on the first and second law analyses for the simple Linde-Hampson cycles used in gas liquefaction systems. Mehrpooya et al [16] investigated the behaviour of an industrial refrigeration cycle with refrigerant propane by the exergy method.…”

Section: Introductionmentioning

confidence: 99%

Comparison of low temperature mixed refrigerant cycles for separation systems

Mafi

Amidpour

Naeynian

2009

SUMMARYNumerous mixed refrigerant cycles (MRCs) were developed in the past several decades in different applications. In this paper, two sets of low temperature MRCs are developed and simulated for a typical olefin plant utilizing a mixture of methane, ethane, propane and nitrogen as cycle working fluid to replace the pure ethylene refrigeration cycle that is used in conjunction with propylene refrigeration cycle in conventional plants. The key parameters of the cycles including mixture compositions and operating pressure levels are optimized to meet the objective of minimum shaftwork in compressor. The results show that different cycle configuration has different optimal mixture composition and low and high operating pressures. The results of exergy analysis reveal that the main location of the exergy loss in the cycles is the heat exchanger system. Also, the Carnot factor versus heat flow diagram is provided to identify the distribution of inefficiencies in the heat exchangers for each cycle. The simulation results show that MRCs can improve the thermodynamic performance of refrigeration system using the optimal working fluid mixture composition, optimal high and low operating pressures and optimal arrangement of the cycle components.

“…Over the past decades, JT cycle has also been extensively used in low-temperature small refrigerators for the applications of infrared detecting, space technology, cryobiology and cryogenic storage, due to its simple structure, reliable performance and low cost [1]. Recent developments of JT cycle low-temperature small refrigerator based on a commercial oil-lubricated compressor operating with refrigerant mixtures draw many concerns [2,3].…”

Section: Introductionmentioning

confidence: 99%

Theoretical study on an innovative ejector enhanced Joule-Thomson cycle

Yu¹,

Chen²,

Li³

2009

SUMMARYThis paper describes an innovative ejector enhanced Joule-Thomson cycle for low-temperature refrigerators. Since an ejector is introduced into the cycle, the cycle performance is profoundly affected by the pressure lift ratio and entrainment ratio of the ejector. As a case study, the performance characteristic of the novel cycle refrigerator using the non-azeotropic refrigerant mixture R14/R23 with the molar fraction of 0.6/0.4 is theoretically investigated in detail. The theoretical results show that in a typical refrigeration temperature range from À651C to À951C, the novel cycle refrigerator has 24.4%-41.5% improvement in coefficient of performance and 60%-220% enhancement in refrigeration capacity when compared to a basic Joule-Thomson cycle low-temperature refrigerator. This achieves a significant advantage as the use of the novel cycle is applied to low-temperature refrigerators for the medical and commercial applications.