“…For the sake of employing similar materials, some more specific details of experimental setup for direct contact heat transfer and design parameters with different levels are present in literature. 4,25,29,35,36 Figure 1.Schematic diagram of experimental apparatus of dual-loop ORC direct contact heat transfer process and optical imaging devices (blue arrows refer to the flow direction of continuous phase and green arrows refer to the flow direction of discrete phase).…”
Section: Methodsmentioning
confidence: 99%
“…Through the previous work, for instance, the heat-transfer properties of the ORC direct contact heat exchange equipment have been explored with the help of volumetric heat transfer coefficient and conventional high-speed video cameras that can be required to collect the real-time images of fluids mixing. 4,29,35 Next, Liu et al. introduced a nondestructive image analysis method to study the vital processes of particle mixing and heat exchange.…”
By bringing two immiscible fluids at different temperatures into a direct contact heat exchanger (DCHE), bubble swarms are produced in the dual-loop ORC direct contact boiling heat transfer process. The aim of this paper is to make effort to explore the interplay between mixing state quality and heat transfer performance of fluids in the DCHE. Through flow visualization of this mixing process, a simple image analysis technique is introduced to represent the formation and evolution of vapor around the injected coolant droplets. Description of the boiling heat transfer process is here achieved by average volumetric heat transfer coefficient (VHTC). Experimental results attest that the proposed mixing index is powerful and sufficient compared with the Betti numbers method for the mixing quality quantification of bubbles inside DCHE. The synergistic association between the fluids mixing process and the heat transfer process is investigated by statistical regression model of new mixing index and VHTC. The contributions, including the data from monitoring practice in ORC heat transfer system and the proposed way, are presented to delve into the transient behaviors comparison of various fluids mixing and heat transfer processes conveniently.
“…For the sake of employing similar materials, some more specific details of experimental setup for direct contact heat transfer and design parameters with different levels are present in literature. 4,25,29,35,36 Figure 1.Schematic diagram of experimental apparatus of dual-loop ORC direct contact heat transfer process and optical imaging devices (blue arrows refer to the flow direction of continuous phase and green arrows refer to the flow direction of discrete phase).…”
Section: Methodsmentioning
confidence: 99%
“…Through the previous work, for instance, the heat-transfer properties of the ORC direct contact heat exchange equipment have been explored with the help of volumetric heat transfer coefficient and conventional high-speed video cameras that can be required to collect the real-time images of fluids mixing. 4,29,35 Next, Liu et al. introduced a nondestructive image analysis method to study the vital processes of particle mixing and heat exchange.…”
By bringing two immiscible fluids at different temperatures into a direct contact heat exchanger (DCHE), bubble swarms are produced in the dual-loop ORC direct contact boiling heat transfer process. The aim of this paper is to make effort to explore the interplay between mixing state quality and heat transfer performance of fluids in the DCHE. Through flow visualization of this mixing process, a simple image analysis technique is introduced to represent the formation and evolution of vapor around the injected coolant droplets. Description of the boiling heat transfer process is here achieved by average volumetric heat transfer coefficient (VHTC). Experimental results attest that the proposed mixing index is powerful and sufficient compared with the Betti numbers method for the mixing quality quantification of bubbles inside DCHE. The synergistic association between the fluids mixing process and the heat transfer process is investigated by statistical regression model of new mixing index and VHTC. The contributions, including the data from monitoring practice in ORC heat transfer system and the proposed way, are presented to delve into the transient behaviors comparison of various fluids mixing and heat transfer processes conveniently.
“…The effect of surfactant addition on void fraction distributions has been investigated by Kleinbart et al [26]. Statistical theories coupled image processing techniques are receiving an increasing interest for measuring flow quantities and local bubble distribution in multiphase flow mechanically agitated vessels [27,19].…”
Understanding the bubble regimes is a fundamental step toward conducting heat transfer enhancement. The non-invasive measurement of mixing inside a direct-contact heat transfer process, using a direct video imaging technology, provides powerful opportunities for characterising the visual observations of the phenomena and quantifying the process complexities previously. Experimental bubble shape feature parameters were obtained by means of the photographic recording technique for a direct-contact evaporator. Four design factors with three levels respectively were analysed for the mixing system that involves the exchange of heat between two immiscible fluids (continuous and dispersed phases). Using the Ripley's K function, new results are presented for two-phase flow mixing which can distinguish differences in the mixing behavior of dispersed phase. In all cases considered, quantitative comparisons of the evolution curves representing different experimental conditions were conducted with reported experimental data. Following the local mixing curve, the current results can also be processed to provide the mixing time found to be in good agreement with available data. The relationship between shape feature parameters of bubbles and volumetric heat transfer coefficient was found to be highly independent on experimental design parameters.
“…Oshida et al (2013) observed the space structure of the nanotubes by 3D-TEM and revealed the detailed structure by HRTEM, which is useful to understand the nano-structure of materials accurately [29]. Recently, we showed an image analysis technique combined with two statistical hypothesis-testing tools including Kolmogorov-Smirnov test and χ 2 test to obtain the p−values for bubble images comparison [30].…”
The purposed of this article is to introduce a novel approach (uniformity measure, U ) based on entropy theory for measuring the micron-particle blend homogeneity of aqueous electrolytes, which applies directly to the imaging data of flow field and does not require contacting and disturbing it. Effectiveness of the new method has been illustrated on synthetic imaging data. To verify the feasibility of our method for real experimental data, we analyze the flow-field images from electrodeposited Zn-Fe-SiO 2 composite coatings process. The numerical results showed that the potential of proposed method was demonstrated successfully to quantitatively establishes association between plating parameters and flow field characteristics. The possible recommendations are to monitor the deposition of micro-particles during the composite electrodeposition processes and to apply this technique for studying a variety of multiphase mixing problems in which assessment of uniformity is required.
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