Analysis of the Flow Characteristics of Plug Nozzle for Cold Air Test with Pintle Shape and Operating Pressure

The collapsing phenomenon of cavitation bubbles generates extremely high local pressures and temperatures that can be utilized for the chemical oxidation process. This process is carried out in cavitation reactors. A Venturi tube is one of the most common forms of hydrodynamic cavitation reactors, which is suitable for industrial scale applications. In this work, the hydraulic performance and efficiency in chemical reaction of a new form of hydrodynamic cavitation reactors, which is called “tandem Venturi,” were studied and compared with the conventional type of the single Venturi. The tandem Venturi is used for enhancement of the chemical reaction of hydrodynamic cavitating flow. The reaction enhancement is useful especially for the reaction of aqueous solutions not containing volatile organic compounds (VOCs). The operating pressure, inlet pressure, flow rate, and consequently the cavitation number were controlled and systematically varied for both single and tandem Venturis. Moreover, a specified amount of H2O2 was injected into the flow as required. The effects of operating pressure and the cavitation number on cavitating flow characteristics for single and tandem Venturis were experimentally observed and the results were compared. In addition, the performance of the tandem-Venturi reactor for degradation of non-VOC contaminants (2-chlorophenol) was studied. Its performance was compared with the performance of a conventional Venturi reactor. Two different categories were conducted for the experiments. In the first category, the effect of the net cavitating flow on degradation of non-VOC for the single and tandem Venturis was compared. In the second category, the effect of H2O2 injection into the cavitating flow on degradation of non-VOC (“cavitation-oxidation” process) was studied. The performance of the single and tandem Venturis for the cavitation-oxidation process was compared. Further investigation was performed to assess the advantage of utilizing the tandem Venturi from the viewpoint of efficiency of the oxidation process. The results of the energy efficiency were compared with the corresponding efficiency of the single Venturi. Finally, the relationship between the main parameters of cavitation reaction flow with the chemical performance was discussed.

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Analysis of Heat and Flow Characteristics on Spray Cooling Heat Transfer with an Optimized Hexagonal Finned Heat Sink

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems ◽

10.4995/ilass2017.2017.4772 ◽

2017 ◽

Author(s):

Faruk Yesildal ◽

Kenan Yakut

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Heat Sink ◽

Cooling Water ◽

Flow Characteristics ◽

Optimization Method ◽

Spray Cooling ◽

Spray Angle ◽

Operating Pressure ◽

Taguchi Optimization

An experimental study was carried out with a hexagonal finned heat sink to obtain valuable information about the thermal and flow characteristics on spray cooling. Water was used as the refrigerant fluid and was atomized by an air-assisted atomizer and some of the variables that affect spray cooling process, such as breakup length and Sauter Mean Diameter (SMD) were obtained using appropriate correlations. The parameters most influential on the Nusselt number were determined and analyzed. Experiments were conducted for optimized conditions. The jet diameter and spray angle were determined via image processing using macroscopic aspects. Nusselt were demonstrated of hexagonal finned heat sink which optimized according to the Taguchi optimization method. The results of the spray analysis showed that SMD decreases with an increase in either air-liquid mass ratio (ALR) or operating pressure resulting in a more uniform spray. As the liquid flow rate increases in all ALR values, the heat transfer rate also increases markedly. As a results of the experiments, Nusselt number, jet width and spray angle correlations were developed. The relationship of ALR-Nu was demonstrated according to fin height and spraying time.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4772

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Effect of Operating Pressure on the Heat Transfer and Particle Flow Characteristics in the Syngas Quench System of an IGCC Process

Transactions of the Korean hydrogen and new energy society ◽

10.7316/khnes.2014.25.1.097 ◽

2014 ◽

Vol 25 (1) ◽

pp. 97-104

Author(s):

Sangbin Park ◽

Joohyang Yang ◽

Junho Oh ◽

In-Soo Ye ◽

Changkook Ryu ◽

...

Keyword(s):

Heat Transfer ◽

Flow Characteristics ◽

Particle Flow ◽

Operating Pressure

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Numerical Simulation on Superheated Steam Fluidized Bed Drying at Different Operating Pressures

International Journal of Food Engineering ◽

10.1515/ijfe-2017-0093 ◽

2017 ◽

Vol 13 (10) ◽

Author(s):

Xiao Zhifeng ◽

Zhang Fan ◽

Xu Lei ◽

Wang Jianhong ◽

Wu Nanxing

Keyword(s):

Numerical Simulation ◽

Fluidized Bed ◽

Superheated Steam ◽

Flow Characteristics ◽

Optimum Operating ◽

Operating Pressure ◽

Drying Process ◽

Two Phase ◽

Fluidized Bed Drying ◽

Drying Technology

AbstractDuring superheated steam fluidized bed drying process, the operating pressure has an important influence on heat and mass transfer characteristics and the vapor-solid two-phase flow characteristics. Based on the two-dimensional unsteady model of rapeseeds drying process, the influence of operating pressure on the superheated steam fluidized bed drying kinetics was revealed by computer numerical simulation. The quantitative analysis of relationship between operating pressure and maximum drying rate was conducted under negative pressure, near atmospheric pressure and high pressure environment, respectively. The optimum operating pressure values for superheated steam fluidized bed drying were obtained with the imported superheated steam temperature and superficial velocity. The simulation results provide a theoretical reference for superheated steam fluidized bed drying technology applying to agro-processing projects.

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Scanning electron microscopy of plant cells using a variable-pressure SEM and cryogenic techniques

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147144 ◽

1993 ◽

Vol 51 ◽

pp. 260-261

Author(s):

M. Yamada ◽

K. Ueda ◽

K. Kuboki ◽

H. Matsushima ◽

S. Joens

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Saturated Vapor ◽

Plant Cells ◽

Variable Pressure ◽

Specimen Preparation ◽

Operating Pressure ◽

Vapor Pressures ◽

Low Temperature Microscopy ◽

Scanning Electron

Use of variable Pressure SEMs is spreading among electron microscopists The variable Pressure SEM does not necessarily require specimen Preparation such as fixation, dehydration, coating, etc which have been required for conventional scanning electron microscopy. The variable Pressure SEM allows operating Pressure of 1˜270 Pa in specimen chamber It does not allow microscopy of water-containing specimens under a saturated vapor Pressure of water. Therefore, it may cause shrink or deformation of water-containing soft specimens such as plant cells due to evaporation of water. A solution to this Problem is to lower the specimen temperature and maintain saturated vapor Pressures of water at low as shown in Fig. 1 On this technique, there is a Published report of experiment to have sufficient signal to noise ratio for scondary electron imaging at a relatively long working distance using an environmental SEM. We report here a new low temperature microscopy of soft Plant cells using a variable Pressure SEM (Hitachi S-225ON).

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