Author
Xiangji Guo
Bio: Xiangji Guo is an academic researcher from Dalian University of Technology. The author has contributed to research in topics: Vortex tube & Vortex. The author has an hindex of 5, co-authored 7 publications receiving 102 citations.
Topics: Vortex tube, Vortex, Starting vortex, Flow stress, Waste heat
Papers
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TL;DR: In this paper, the authors highlight the potential contributions of Ranque-Hilsch vortex tubes in meeting the industrial requirements of energy efficiency improvement, sustainable energy utilization, and waste heat regeneration with its unique energy separation effect.
Abstract: The scope of this review is to highlight the potential contributions of Ranque–Hilsch vortex tubes in meeting the industrial requirements of energy efficiency improvement, sustainable energy utilization, and waste heat regeneration with its unique energy separation effect. Vortex tubes have received significant attention in recent years, as they meet the current requirements of energy conservation with their energy saving and environment-friendly operating modes. Vortex tubes have been widely exploited for the unique energy separation phenomenon and the ability to provide instant cooling and heating effects, with air as the most common working fluid. The functions fulfilled by the vortex tubes are numerous. In addition to the sole single gas-phase, there may be phase changing processes involved in vortex tubes, and the adopted purposes of vortex tubes may be broadly divided into energy separation and mass separation. The mass separation process in a vortex tube is more complex, as the phase change and component separation is interrelated. The main objective of this review relates to the analysis, carding, and construction of application and operation mechanism of vortex tubes from newly emerging research fields in order to derive a clear classification and promising techniques. Thus, the main content is divided into two parts to be summarized and discussed. The first is focused on energy or temperature separation of which the hot or cold fluid stream produced by a vortex tube is the main purpose; the second relates to the mass separation in which the mass or component separation, usually accompanied by phase change and temperature variation, is produced by a vortex tube. In each part, the operation mechanism, system configuration, performance influencing factors, and status of current techniques are introduced and described.
48 citations
TL;DR: In this article, a quasi-cylindrical approximation was adopted to predict the size of the vortex core size by considering the pressure gradient, and a novel analysis was conducted on the energy separation mechanism, in which the large-scale vortex structure plays an important role.
Abstract: The flow structure and energy separation considering the effect of cold mass fraction in a Ranque–Hilsch vortex tube were investigated computationally based on the vortex breakdown theory The velocity distributions and pressure fields for nine different cold mass fractions were considered A quasi-cylindrical approximation was adopted to predict the size of the vortex core size by considering the pressure gradient Further, a novel analysis was conducted on the energy separation mechanism, in which the large-scale vortex structure plays an important role; for example, increasing the cold mass fraction within a certain range can result in bigger vortex cores, yielding better energy separation performance Finally, the type of vortex breakdown was also discussed for further understanding the vortex structure This paper offers a new idea on the manner in which the external conditions (here, cold mass fraction) affect the large-scale vortex structure and on the subsequent energy separation performance
36 citations
TL;DR: In this paper, a critical review and discussion on the current studying methods, findings and differences on the flow structures in vortex tube is presented, and future scopes were proposed on the experimentally and theoretically verification of these flow structures and their effects on the energy separation process and performance.
Abstract: Various methods had been taken for the flow field studies, among them, qualitative visualizations and probe intrusive measurements have a long history and had been adopted since last 50s, while laser non-intrusive measurements and numerical simulations are the emerging methods, especially the former. Nowadays, more and more researchers have realized there are specific and regular flow structures in the strong turbulence of vortex tube, and the flow structures have great significance on understanding the energy separation process and performance. However, there still did not exist a review on the flow structure studies. The aim of this paper is to offer a critical review and discussion on the current studying methods, findings and differences on the flow structures in vortex tube. In addition, future scopes were proposed on the experimentally and theoretically verification of these flow structures and their effects on the energy separation process and performance.
31 citations
TL;DR: In this paper, a heat source model is proposed for the simulation of the temperature rises in the laser deposition melting additive manufacturing process, which can be used to predict the microstructural evolutions in a multiscale strategy including the grain cluster scale and single grain scale in Monte Carlo model.
30 citations
TL;DR: In this paper, a 2D laser Doppler velocimetry (LDV) measurement was adopted to investigate the mean flow field on the meridian plane, and the distributions of the axial and radial velocities, and particularly the reverse flow boundary, were obtained for understanding the characteristics of large-scale vortex structures.
Abstract: In this study, transparent vortex tubes of diameter 30 mm were designed for the main tube visualisation and a 2D laser Doppler velocimetry (LDV) measurement was adopted to investigate the mean flow field on the meridian plane. The distributions of the axial and radial velocities, and particularly the reverse flow boundary, were obtained for understanding the characteristics of large-scale vortex structures. Various operation conditions with different cold mass fractions (0.1–0.9), tube lengths (360 mm, 600 mm, and 900 mm), and inlet pressures (0.1 bar and 0.2 bar) were studied to reveal how the reverse flow boundary affects the energy separation performance. The LDV results show that the mean axial velocity distribution present good axial symmetry, and increasing the cold mass fraction results in an expansion of the reverse flow boundary as reported for previous numerical calculations. A deterioration in the energy separation performance due to an excessively short or long tube was revealed, and the proposed tube optimization criteria were proven.
29 citations
Cited by
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TL;DR: The microstructure of metals depends on the additive manufacturing (AM) process and the process parameters, and experimentation on different process parameters for different materials is costl... as discussed by the authors.
Abstract: The microstructure of metals depends on the additive manufacturing (AM) process and the process parameters. However, experimentation on different process parameters for different materials is costl...
166 citations
TL;DR: In this paper, an updated review of the advances on modified technologies to solve the drawbacks of CO2 refrigeration is provided and recent progress on the energy efficiency improvement is summarized, followed by a detailed discussion on different modified technologies as well as their operating fundamental, technical features and performance.
73 citations
TL;DR: In this paper, a computational framework is developed to investigate the process-structure-property relationship for additive manufacturing of Ti-6Al-4V alloy, which incorporates experimentally informed two-phase α+β morphologies within prior β-grains, which are widely observed in the as-built AM components.
54 citations
TL;DR: In this paper, the authors highlight the potential contributions of Ranque-Hilsch vortex tubes in meeting the industrial requirements of energy efficiency improvement, sustainable energy utilization, and waste heat regeneration with its unique energy separation effect.
Abstract: The scope of this review is to highlight the potential contributions of Ranque–Hilsch vortex tubes in meeting the industrial requirements of energy efficiency improvement, sustainable energy utilization, and waste heat regeneration with its unique energy separation effect. Vortex tubes have received significant attention in recent years, as they meet the current requirements of energy conservation with their energy saving and environment-friendly operating modes. Vortex tubes have been widely exploited for the unique energy separation phenomenon and the ability to provide instant cooling and heating effects, with air as the most common working fluid. The functions fulfilled by the vortex tubes are numerous. In addition to the sole single gas-phase, there may be phase changing processes involved in vortex tubes, and the adopted purposes of vortex tubes may be broadly divided into energy separation and mass separation. The mass separation process in a vortex tube is more complex, as the phase change and component separation is interrelated. The main objective of this review relates to the analysis, carding, and construction of application and operation mechanism of vortex tubes from newly emerging research fields in order to derive a clear classification and promising techniques. Thus, the main content is divided into two parts to be summarized and discussed. The first is focused on energy or temperature separation of which the hot or cold fluid stream produced by a vortex tube is the main purpose; the second relates to the mass separation in which the mass or component separation, usually accompanied by phase change and temperature variation, is produced by a vortex tube. In each part, the operation mechanism, system configuration, performance influencing factors, and status of current techniques are introduced and described.
48 citations
TL;DR: In this paper, an exceptional view on the multi-scale integrated computational modelling and data-driven methods in the additive manufacturing of metallic materials in the framework of computational simulation is presented.
Abstract: In the current review, an exceptional view on the multi-scale integrated computational modelling and data-driven methods in the Additive manufacturing (AM) of metallic materials in the framework of...
44 citations