Investigation of single-phase flow patterns in a model flash evaporation chamber using PIV measurement and numerical simulation

Jin, Weiya; Low, S.C.

doi:10.1016/s0011-9164(02)00929-3

Cited by 26 publications

(7 citation statements)

References 6 publications

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“…Kim et al [14] carried out experiments on pool flash evaporation and identified the critical time at which the rate of ebullition and evaporation diminishes abruptly and the critical initial water temperature at which the expected observed trend of decreasing non-equilibrium temperature difference (NETD) with decreasing depth reverses itself. Jin et al [15,16] studied the flow patterns of flash evaporation experimentally and theoretically. The influence of water level and flow rate on flow patterns was studied with high speed camera technology and PIV measurement.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on the heat transfer characteristics of vacuum spray flash evaporation cooling

Cheng

Peng

Chen

et al. 2016

International Journal of Heat and Mass Transfer

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a b s t r a c tVacuum spray flash evaporation cooling (VSFEC) is considered as an alternative effective method for dissipating high heat flux in the field of space thermal control. In this paper, a VSFEC experiment system has been developed to investigate the influence of spray flow rate and spray height on the heat transfer characteristics of VSFEC. The experiment results show that the heat flux can be removed efficiently from the heat source in VSFEC system with a very small spray flow rate, which is only one third of that of conventional spray cooling under the same heat flux. And an optimal flow rate exists in VSFEC, at which the heat transfer approaches to a highest value, it is different from conventional spray cooling in which the heat flux increases with the increasing of spray flow rate all the time, in VSFEC, the heat flux firstly increases and then decreases with increasing of flow rate. Since VSFEC system is an open-loop heat dissipation system, it has very important significance that based on the optimal flow rate to reduce working medium consumption, especially for space thermal control system which has a strict limit on weight. In addition, spray height has an important effect on the heat transfer characteristics of VSFEC and an optimal spray height is also obtained at which the maximum value of heat flux can be achieved.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation on the heat transfer characteristics of vacuum spray flash evaporation cooling

Cheng

Peng

Chen

et al. 2016

International Journal of Heat and Mass Transfer

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“…The vector file was opened and the errors were replaced by 0, 0, 1. [28] The vector file was then opened in software Tecplot [29] to create vector images to be analyzed and printed [30]. Figure 23 shows the set up of laser based PIV system including charge-coupled camera (CCD), laser power supply, 2 Yag lasers, a laser pulse synchronizer and a computer monitoring system.…”

Section: Particles Testing Using Pivmentioning

confidence: 99%

Innovative Coal Solids-Flow Monitoring and Measurement Using Phase-Doppler and Mie Scattering Techniques

Lee¹

2010

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Fuel flow to individual burners is complicated and difficult to determine on coal fired boilers, since coal solids were transported in a gas suspension that is governed by the complex physics of two-phase flow. The objectives of the project were the measurements of suspended coal solidsflows in the simulated test conditions. Various extractive methods were performed manually and can give only a snapshot result of fuel distribution. In order to measure particle diameter & velocity, laser based phase-Doppler particle analyzer (PDPA) and particle image velocimetry (PIV) were carefully applied. Statistical methods were used to analyze particle characteristics to see which factors have significant effect. The transparent duct model was carefully designed and fabricated for the laser-based-instrumentation of solids-flow monitoring (LISM).The experiments were conducted with two different kinds of particles with four different particle diameters. The particle types were organic particles and saw dust particles with the diameter range of 75~150 micron, 150~250 micron, 250~355 micron and 355~425 micron. The densities of the particles were measured to see how the densities affected the test results.Also the experiment was conducted with humid particles and fog particles. To generate humid particles, the humidifier was used. A pipe was connected to the humidifier to lead the particle flow to the intersection of the laser beam. The test results of the particle diameter indicated that, the mean diameter of humid particles was between 6.1703 microns and 6.6947 microns when the humid particle flow was low. When the humid particle flow was high, the mean diameter was between 6.6728 microns and 7.1872 microns. The test results of the particle mean velocity indicated that the mean velocity was between 1.3394 m/sec and 1.4556 m/sec at low humid particle flow. When the humid particle flow was high, the mean velocity was between 1.5694 m/sec and 1.7856 m/sec.The Air Flow Module, TQ AF 17 and shell ondina oil were used to generate fog particles. After the oil was heated inside the fog generator, the blower was used to generate the fog. The fog flew Page IV along the pipe to the intersection of the laser beam. The mean diameter of the fog particles was 5.765 microns. Compared with the humid particle diameter, we observed that the mean diameter of the fog particles was smaller than the humid particles. The test results of particle mean velocity was about 3.76 m/sec. Compared with the mean velocity of the humid particles, we can observed the mean velocity of fog particles were greater than humid particles.The experiments were conducted with four different kinds of particles with five different particle diameters. The particle types were organic particles, coal particles, potato particles and wheat particles with the diameter range of 63~75 micron, less than 150 micron, 150~250 micron, 250~355 micron and 355~425 micron.To control the flow rate, the control gate of the particle dispensing hopper was adjusted to 1/16 open rate, 1/8 ...

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“…The saturation temperature is determined by the distance of the particles from an assumed fixed free interface, whereas the liquid level height varies very drastically during the actual flash evaporation process. Jin and Low [11] used a single-phase model to investigate the distribution of flow fields within the flash evaporation chamber. Dietzel et al [12] investigated three different models of phase transition in a flash evaporation process in the system based on Eulerian-Eulerian two-phase flow, with mass transfer rates being calculated by local vapor and saturation pressure differences, entropy and saturation entropy differences, and local heat transfer rates, respectively.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation Method for Flash Evaporation with Circulating Water Based on a Modified Lee Model

Li,

Wang,

Man

et al. 2023

Energies

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Flash evaporation processes are widely adopted in the desalination, food processing, waste heat recovery and other industries for heat extraction or product separation. In this paper, a pressure-driven phase transition model is developed by improving the Lee model and combined with the VOF (Volume of Fluid) method to numerically simulate the flash evaporation process. In this modified Lee phase transition model, the driving force for the rates of the local phase transition is calculated using the local temperature and static pressure magnitude. Numerical simulations are carried out in a water-circulating flash chamber and compared with the experimental results to obtain the values of the time relaxation parameters. And the non-equilibrium fraction of the outlet water can be effectively obtained under different conditions of flow rate, inlet temperature and initial liquid level height. The time relaxation factor takes values from 0.195 to 0.43 (Pout,v = 19.9 kPa) and from 0.31 to 0.92 (Pout,v = 31.2 kPa) with increasing superheat. In addition, the model can effectively represent the evolution of the unstable flow flash evaporation from the initial rapid boiling state to dynamic equilibrium.

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Investigation of single-phase flow patterns in a model flash evaporation chamber using PIV measurement and numerical simulation

Cited by 26 publications

References 6 publications

Experimental investigation on the heat transfer characteristics of vacuum spray flash evaporation cooling

Experimental investigation on the heat transfer characteristics of vacuum spray flash evaporation cooling

Innovative Coal Solids-Flow Monitoring and Measurement Using Phase-Doppler and Mie Scattering Techniques

Numerical Simulation Method for Flash Evaporation with Circulating Water Based on a Modified Lee Model

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