Systematic study on heat transfer and surface hydrodynamics of a vertical heat tube in a fluidized bed of FCC particles

Yao, Xiuying; Zhang, Yongmin; Lu, Chunxi; Han, Xiaoxiang

doi:10.1002/aic.14635

Cited by 25 publications

(20 citation statements)

References 28 publications

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“…A multisectional copper tube heated electrically was used to simulate a vertical heat tube in a FCC external catalyst cooler and measure the axial and radial profiles of heat-transfer coefficients. More details about the experiment unit were provided in Yao et al 39 Figure 3 shows the two external catalyst coolers used in this study, that is, a base catalyst cooler and a new annular catalyst cooler. It should be noted that the base catalyst cooler shown in Figure 3a is in fact a redrawn threedimensional picture of the catalyst cooler studied in Yao et al 39 It is the structure of the gas distributors that distinguishes the two catalyst coolers.…”

Section: Methodsmentioning

confidence: 99%

“…The newly developed two methods for measuring local heat-transfer coefficient and tube surface hydrodynamics, which was described in more detail in our previous publication, 39 was reused to measure the axial and radial profiles of heat-transfer coefficient as well as the packet parameters on tube surfaces in the new annular catalyst cooler. By comparing these experimental results with those measured in the base catalyst cooler, 39 the heat transfer intensification regions can be more explicitly located. Moreover, the relationship between the changed heattransfer coefficient and the hydrodynamics on heat tube surface can also be revealed more clearly.…”

Section: Introductionmentioning

confidence: 99%

“…39,46 In Yao et al, 39 a special electrically heated tube was designed to measure both axial and radial profiles of heat-transfer coefficient. It is found that the heat-transfer coefficient was almost not influenced by the axial height.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the relationship between the changed heattransfer coefficient and the hydrodynamics on heat tube surface can also be revealed more clearly. To facilitate readers' understanding, some contents in Yao et al, 39 for example, some important data, equations, figures and descriptive texts were reused in the following content.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the heat transfer intensification mechanism for a new fluidized catalyst cooler

Yao

Zhang

et al. 2015

AIChE Journal

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A small cold model was employed to investigate the heat-transfer mechanism for a new fluidized catalyst cooler. Local heat-transfer coefficients (h) and tube surface hydrodynamics were systematically measured by a specially designed heat tube and an optical fiber probe. The higher total h further validated the feasibility of the heat transfer intensification method used in the new catalyst cooler, which indicated that the induced higher packet renewal frequency due to the nonuniform gas distribution played a dominant role in its increased hs. Strongest heat transfer intensification effect was located at r/R w >0.8 below the heat transfer intensification height. The changes of the mean packet residence time in the radial and axial directions and with superficial gas velocity were all agreeable with the measured hs according to the packet renewal theory. This further demonstrated the feasibility of the experimental method for tube surface hydrodynamics.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of the heat transfer intensification mechanism for a new fluidized catalyst cooler

Yao

Zhang

et al. 2015

AIChE Journal

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“…As mentioned in a previous study [57] , both factors are beneficial to increase the heat transfer coefficient. The ACC has combined features of both up-and down-flow catalyst coolers.…”

Section: Particle Radial Distributionmentioning

confidence: 52%

CFD investigation of gas-solids flow in a new fluidized catalyst cooler

Yao

Zhang

et al. 2016

Powder Technology

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In our previous work, a new concept of annular catalyst cooler (ACC) was recently proposed and validated experimentally, which showed that an internal circulation of solids can be formed by using two gas distributors and both hydrodynamics and heat transfer can be largely improved. The current work simulated the detailed hydrodynamics of gas-solids flow to advance our understanding of the ACC by using the two-fluid model.. The influence of effective particle diameter dp * and specularity coefficient in solids wall boundary condition are examined and compared with experimental data. Optimum values of dp * =170 m and =0.3 are determined and used in the simulations. The results show that by properly selecting the gas velocities and the position of heat transfer tube, internal solids circulation can be formed. TheACC has a combined hydrodynamic feature of up-and down-flow catalyst coolers with bigger solids volume fraction and smaller particle resident time, which are beneficial for improving heat transfer coefficients. Detailed hydrodynamics of gas-solids flow are obtained, and the influential parameters are examined, which provides valuable information on the design and optimization of such new ACCs.

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Sustainable Heat Generation in Flow from a Molecular Solar Thermal Energy Storage System

Magson,

Maggiolo,

Kalagasidis

et al. 2024

Adv Energy and Sustain Res

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As the global deployment of renewable technologies accelerate, finding efficient ways to store energy will aid in responding to shifting energy demands. A prospective option not only in harvesting solar energy but also in emission‐free heating is MOlecular Solar Thermal (MOST) energy storage. A central part of MOST applications is to develop methods to release the stored energy. Herein, the Quadricyclane (QC)‐to‐Norbornadiene catalyzed back reaction is explored in a specially designed packed‐bed reactor. Four distinctly sized and purposely synthesized platinum on activated carbon catalysts are studied to trigger the heat release from the energy‐dense QC isomer. The catalysts are fully characterized using a variety of structural, surface, and spectroscopic techniques. Parameters to optimize catalytic conversion and heat release in flow conditions are explored including particle size and packing behavior, flow rates, and molecular residence times. Moreover, using CO pulse chemisorption technique, site time yield values and a turnover number are reported. Complementary to the flow reactions, computational fluid dynamic simulations applying lattice Boltzmann methods to two catalytic packed beds of different size ranges are done to evaluate fluid‐dynamic behavior within the reactor bed to ascertain the ideal particle size and packing density for catalysis in MOST applications.

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Systematic study on heat transfer and surface hydrodynamics of a vertical heat tube in a fluidized bed of FCC particles

Cited by 25 publications

References 28 publications

Investigation of the heat transfer intensification mechanism for a new fluidized catalyst cooler

Investigation of the heat transfer intensification mechanism for a new fluidized catalyst cooler

CFD investigation of gas-solids flow in a new fluidized catalyst cooler

Sustainable Heat Generation in Flow from a Molecular Solar Thermal Energy Storage System

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