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- 2019
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Gao, Zhi xin, et al.
(författare)
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Progress of passive enhanced heat transfer tubes
- 2017
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Ingår i: Xiandai Huagong/Modern Chemical Industry. - 0253-4320. ; 37:3, s. 24-30
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Forskningsöversikt (refereegranskat)abstract
- A review of several typical enhanced heat transfer tubes such as corrugated tube, transversally corrugated tube, twisted tube and spiral fluted tube, is carried out. Compared with smooth wall tube, these enhanced tubes have higher heat exchange capacity and better anti - fouling ability. Besides, the heat transfer efficiency can be promoted to a higher level if the objects that can disturb flow are put in the tubes. However, higher heat transfer efficiency of such enhanced heat transfer tubes can only be achieved under certain conditions. Therefore, new heat transfer tubes that could avoid the formation of mobile dead-zone should be designed to meet the broad applications or facilitate better heat transfer effect.
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| 4. |
- Hou, Cong wei, et al.
(författare)
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Parametric analysis on throttling components of multi-stage high pressure reducing valve
- 2018
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 128, s. 1238-1248
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Tidskriftsartikel (refereegranskat)abstract
- High pressure reducing valve (HPRV) is widely used for pressure and temperature control of heated steams in power plant and other related process engineering. The structures of throttling components inside HPRVs have important effects on the control performances. In this paper, a parametric study of throttling components in a multi-stage high pressure reducing valve (MSHPRV) is carried out, including the relative angle of inner and outer porous shrouded holes, the orifice plate thickness, the number of orifice plates and the diameter of plate holes. A numerical model is established to investigate internal flow and throttling characteristics with RNG k-ε model, and it is validated by the theoretical flux calculation. The results show that, the relative angle set as 180° can obtain the largest decompression pressure when steam flows through porous shrouded valve core, while the turbulence degree is the lowest. Setting one orifice plate can decrease the turbulent dissipation rate. The plate thickness has less influence on throttling effects. For ensuring the outlet flux, plate holes with smaller diameters should be chosen with a better flowing property on thermodynamic parameters. The work can be referred by the design work of throttling components in MSHPRV and it can also benefit the further research on similar HPRVs.
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| 5. |
- Jin, Zhi-jiang, et al.
(författare)
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A parametric study of hydrodynamic cavitation inside globe valves
- 2018
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Ingår i: Journal of Fluids Engineering. - : ASME International. - 0098-2202 .- 1528-901X. ; 140:3
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Tidskriftsartikel (refereegranskat)abstract
- Hydrodynamic cavitation that occurs inside valves not only increases the energy consumption burden of the whole piping system but also leads to severe damages to the valve body and the piping system with a large economic loss. In this paper, in order to reduce the hydrodynamic cavitation inside globe valves, effects of valve body geometrical parameters including bending radius, deviation distance, and arc curvature linked to in/ export parts on hydrodynamic cavitation are investigated by using a cavitation model. To begin with, the numerical model is compared with similar works to check its accuracy. Then, the cavitation index and the total vapor volume are predicted. The results show that vapor primarily appears around the valve seat and connecting downstream pipes. The hydrodynamic cavitation does not occur under a small inlet velocity, a large bending radius, and a large deviation distance. Cavitation intensity decreases with the increase of the bending radius, the deviation distance, and the arc curvature linked to in/export parts. This indicates that valve geometrical parameters should be chosen as large as possible, while the maximal fluid velocity should be limited. This work is of significance for hydrodynamic cavitation or globe valve design.
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| 6. |
- Jin, Zhi Jiang, et al.
(författare)
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Cavitating flow through a micro-orifice
- 2019
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Microfluidic systems have witnessed rapid development in recent years. As one of the most common structures, the micro-orifice is always included inside microfluidic systems. Hydrodynamic cavitation in the micro-orifice has been experimentally discovered and is harmful to microfluidic systems. This paper investigates cavitating flow through a micro-orifice. A rectangular micro-orifice with a l/d ratio varying from 0.25 to 4 was selected and the pressure difference between the inlet and outlet varied from 50 to 300 kPa. Results show that cavitation intensity increased with an increase in pressure difference. Decreasing exit pressure led to a decrease in cavitation number and cavitation could be prevented by increasing the exit pressure. In addition, the vapor cavity also increased with an increase in pressure difference and l/d ratio. Results also show the pressure ratio at cavitation inception was 1.8 when l/d was above 0.5 and the cavitation number almost remained constant when l/d was larger than 2. Moreover, there was an apparent difference in cavitation number depending on whether l/d was larger than 1.
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| 7. |
- Jin, Zhi Jiang, et al.
(författare)
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Computational fluid dynamics analysis on orifice structure inside valve core of pilot-control angle globe valve
- 2018
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. - : SAGE Publications. - 0954-4062 .- 2041-2983. ; 232:13, s. 2419-2429
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Tidskriftsartikel (refereegranskat)abstract
- A novel pilot-control angle globe valve is proposed, and it has an obvious advantage of energy conservation during its opening and closing process. In pilot-control angle globe valve, the opening and closing forces are related to the orifice located inside the valve core. In this paper, the effects of orifice diameter are thoroughly studied under different working conditions such as valve core displacements and inlet velocities. To begin with, the numerical model is validated by comparing similar angle valves, and then the flow and loss coefficients under different orifice diameters are discussed. It is found that the effects of orifice diameter on force acting on valve core depend on valve core displacement and inlet velocity. Thus different valve core displacements and inlet velocities combined with different orifice diameters are further studied. It is also found that when the orifice diameter is larger than 12 mm, pilot-control angle globe valve cannot be used under small inlet velocity or large valve core displacement. In addition, formulas to calculate forces on valve core are proposed for further orifice design. This work can be referred in process industries especially in a piping system with orifice plates or globe valves.
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| 8. |
- Jin, Zhi jiang, et al.
(författare)
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Effects of pitch and corrugation depth on heat transfer characteristics in six-start spirally corrugated tube
- 2017
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 108, s. 1011-1025
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Tidskriftsartikel (refereegranskat)abstract
- Spirally corrugated tube is one of the most important parts of coaxial heat exchangers. It can greatly improve the heat transfer efficiency of heat exchangers. Here, a novel spirally corrugated tube with six-start is proposed. However, up to now, there is little literature about the heat transfer performance and flow field of this novel six-start spirally corrugated tube. In this paper, the effects of geometric parameters (pitch p, corrugation depth e), Reynolds number Re and fluid properties on the heat transfer performances are investigated based on the validated numerical model. The results show that with the increasing of pitch p, both the heat transfer coefficient h and Nusselt number Nu decrease gradually. Meanwhile, with the increasing of corrugation depth e, both the secondary flow velocity vxy and the vorticity of longitudinal vortex increase gradually. Moreover, under the same working condition, the heat transfer performances of the six-start spirally corrugated tube are affected by both the working medium and Reynolds number. Finally, a criterion correlation for heat transfer calculation in the six-start spirally corrugated tube is proposed and validated to be reliable and suitable. This work can reveal the enhanced heat transfer mechanism of the six-start spirally corrugated tube and benefit the further research on heat transfer characteristics of multi-start spirally corrugated tube or other related devices.
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| 9. |
- Jin, Zhi-jiang, et al.
(författare)
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Pressure Drop Analysis of Pilot-Control Globe Valve With Different Structural Parameters
- 2017
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Ingår i: Journal of Fluids Engineering. - : ASME International. - 0098-2202 .- 1528-901X. ; 139:9
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Tidskriftsartikel (refereegranskat)abstract
- Pilot-control globe valve (PCGV) can use the pressure drop caused by fluid flowing through the orifice located at valve core bottom to open or close the main valve using a small pilot valve. In this paper, computational fluid dynamics (CFD) method is adopted to analyze the pressure drop before and after valve core of PCGV and minor loss of orifice under different structural parameters and inlet velocities, and the simulation results show a good agreement with the experimental results. It turns out that the valve diameters, orifice diameters, and pilot pipe diameters have great influences on the pressure drop and the loss coefficient. Moreover, an expression is proposed which can be used to calculate minor loss coefficient, then to estimate the pressure drop and driving force of a PCGV within limited conditions. This paper can be referenced as guidance for deciding the dimension of structural parameters and spring stiffness during design process of a PCGV.
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| 10. |
- Qian, Jin Yuan, et al.
(författare)
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Effects of dimple cone angles on heat transfer and pressure drop in a dimple jacketed heat exchanger
- 2017
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Ingår i: Proceedings of CHT-17 ICHMT International Symposium on Advances in Computational Heat Transfer, 2017. - 9781567004618 ; , s. 2013-2020
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Konferensbidrag (refereegranskat)abstract
- A Dimple Jacket Heat Exchanger (DJHE) is designed for the Chemical Post-Processing Integrated Equipment (CPPIE) to enhance the heat transfer performance during chemical reaction, crystallization and drying processes. In this paper, a 3D model of a DJHE is established. Dynamic variation of temperature inside the DJHE is compared with experimental data to validate the accuracy of the numerical method. Then, by choosing one dimple from the whole DJHE as the research object, the effects of different dimple cone angles on heat transfer and pressure drop characteristics are analyzed with the validated method. The results show that the dimple cone angle has an obvious effect on the heat transfer and pressure drop performance. This work can reduce the uncertain design of DJHE, and it can also be referred by similar research works on dimple surfaces.
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