The Effect of Wet Compression on a Centrifugal Compressor for a Compressed Air Energy Storage System

Sun, Jianting; Zhou, Xin; Qi, Liang; Zuo, Zhigang; Chen, Haisheng

doi:10.3390/en12050906

Cited by 12 publications

(5 citation statements)

References 42 publications

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“…The larger the droplet diameter, the more the centrifugal force is affected; hence, droplets flock toward the shroud. These results tend to be similar to previous studies on wet compression [22,23].…”

Section: Effect Of the Droplet Size On The Aerodynamic Performance Of...supporting

confidence: 93%

Wet Compression Study for an Aero-Thermodynamic Performance Analysis of a Centrifugal Compressor at Design and Off-Design Points

Kang

Kim

2022

Processes

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In this study, to analyze the effect of wet compression technology on the aero-thermodynamic performance of a centrifugal compressor, a numerical analysis study was conducted on the design point and off-design point. Wet compression technology sprays water droplets at the inlet of the compressor. During the compression process, water droplets evaporate, reducing the heat of compression and reducing the compression work, which improves the efficiency of the compressor. In wet compression technology, detailed research is needed for the application to compressors because the droplet behavior affects the internal flow. The main parameters for wet compression technology are the droplet size and injection rate selection, and the flow inside the compressor changed by the droplet behavior was analyzed. When the droplet size and injection rate were changed at the design point and the off-design point, it was confirmed that a small droplet size was effective in both areas, and it was confirmed that the performance improved as the flow rate increased. The internal flow changed greatly depending on the size of the droplet. As a result, the centrifugal compressor to which the wet compression technology was applied had a lower outlet temperature than dry compression at both the design point and the off-design point and had increases in the pressure ratio and efficiency. However, the surge margin decreased by about 2% in the surge region. The reason is that due to high-speed rotation, particles move in the outer diameter direction and are driven into a tip-leakage flow, and many stagnant flows occur without flowing into the main flow. Through the study results, it was possible to understand the effects of wet compression technology on the performance and efficiency increase of centrifugal compressors and the effects of particle behavior on the internal flow of the compressor at the off-design point.

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Section: Effect Of the Droplet Size On The Aerodynamic Performance Of...supporting

confidence: 93%

Wet Compression Study for an Aero-Thermodynamic Performance Analysis of a Centrifugal Compressor at Design and Off-Design Points

Kang

Kim

2022

Processes

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“…In this paper, the increase of water injection ratio not only enhances the evaporative cooling but also deteriorates the additional losses. 36 In terms of work reduction, although it can achieve greater temperature decline, water injection ratio of 0.4% cannot reduce more compression work, which indicates that wet compression has achieved its optimal effect. Less water injection means less water power consumption, so for this supercritical air stage, the optimum water injection ratio is 0.3%.…”

Section: Resultsmentioning

confidence: 99%

Numerical study on wet compression in a supercritical air centrifugal compressor

Sun

Hou

Zuo

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part A:

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Wet compression is widely used to reduce compression work and improve efficiency in gas turbines. However, wet compression has not been industrially applied in the compressed air energy storage system (only few studies on isothermal compressed air energy storage system exist), which has an urgent demand to reduce the compression work. The high-pressure section of the compressed air energy storage system usually contains supercritical air, and the influence of supercritical wet compression is not yet clear. Thus, in this study, supercritical wet compression was numerically investigated in a centrifugal compressor used for the compressed air energy storage system, and its effects on performance and internal flow were also studied. The results show that the ideal maximum evaporation of water droplets in supercritical air is very low, which limits the maximum available water injection ratio; however, wet compression still has some benefits, such as increasing the total pressure ratio and isentropic efficiency and reducing the compression specific work. Moreover, wet compression reduces the diffuser loss but raises the wake loss in the impeller at the near-stall point. For this compressor, the optimum water injection ratio is 0.3%, which reduces the specific work by 0.65% at the designed pressure ratio.

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“…In previous studies, 21,22,[32][33][34] when calculating the compressor efficiency, the increase in the mass flow rate and energy caused by the gas injection was ignored. This is because the compressor efficiency was not the focus of these studies, and the injection mass flow rate was low.…”

Section: Principle Of the Compressor With Induced Structure And The A...mentioning

confidence: 99%

Effect of the design parameters of induced structures on the sensitivity of compressor efficiency and static pressure of induced structure inlets

Zhu

Wang

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part D:

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A gas-entraining diffuser exhaust gas recirculation (EGR) was proposed to induce the entry of the exhaust gas into the diffuser, to completely utilize the lower static pressure at the diffuser for reducing engine fuel consumption owing to the low engine backpressure. Thus, the induced structure was designed such that a large amount of exhaust gas enters the compressor diffuser. To improve the compressor efficiency and reduce the static pressure at the induced structure inlet, the design parameters of the induced structure (induced angle, induced effective inlet area, parallel part width, and position of the induced structure inlet) were investigated using numerical methods. The results show that the peak compressor efficiency reduced by 4% compared with the compressor prototype, and up to 90% of the compressor efficiency reduction is attributed to the induced gas entering the diffuser, except for the 10% induced gas ratio scenario over the near-choking point. This is because the entropy generation of the induced structure is close to 10% of the entropy generation increase in the diffuser system due to the induced gas at a medium flow rate. Second, in most cases, the compressor efficiency and static pressure of the induced structure inlet increase or decrease simultaneously as the design parameters vary. To select the best induced structure, it is necessary to compromise between the compressor efficiency and static pressure of the induced structure inlet. In fact, the compressor efficiency changes by less than 1% by varying the design parameters of the induced structure, compared with case ID1. This demonstrates that the design parameters have little effect on the compressor efficiency. Compared with the compressor efficiency, the static pressure of the induced structure inlet is more sensitive to the design parameters, particularly the induced effective inlet area and the position of the induced structure inlet.

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The Effect of Wet Compression on a Centrifugal Compressor for a Compressed Air Energy Storage System

Cited by 12 publications

References 42 publications

Wet Compression Study for an Aero-Thermodynamic Performance Analysis of a Centrifugal Compressor at Design and Off-Design Points

Wet Compression Study for an Aero-Thermodynamic Performance Analysis of a Centrifugal Compressor at Design and Off-Design Points

Numerical study on wet compression in a supercritical air centrifugal compressor

Effect of the design parameters of induced structures on the sensitivity of compressor efficiency and static pressure of induced structure inlets

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