The Experts below are selected from a list of 12816 Experts worldwide ranked by ideXlab platform
A H Shamsuddin - One of the best experts on this subject based on the ideXlab platform.
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Repowering of existing AL-Hartha Gas-fuelled conventional steam power plant with molten salt cavity tubular solar central receiver
Clean Technologies and Environmental Policy, 2014Co-Authors: Mahmood S Jamel, A. Abd Rahman, A H ShamsuddinAbstract:This paper introduces a new method to repower the existing equipment of the AL-Hartha steam plant located in Basra, Iraq, using a molten salt cavity tubular solar central receiver (SCR). Cycle Tempo is used to simulate the existing natural Gas-fuelled conventional steam power cycle with consideration of the heat and pressure losses. The heliostat field and the central receiver subsystems are coded using MATLAB. The model couples the heat balance with the temperature computation of the receiver walls for calculation and analysis of the thermal losses. The proposed modified codes are capable of calculating heat losses, evaluating the integrated power plant and satisfying a wide range of SCRs. The results are verified against plant data and previous works in the literature and good agreement is obtained. The results show the potential of using a molten salt cavity tubular SCR for low-range temperature feedwater preheating, as well as the optimum scheme for the integration of the existing plant with an SCR. It is observed that the maximum improvement for the existing AL-Hartha steam plant and the integrated molten salt cavity tubular SCR is obtained by substituting the bleed steam in all the high-pressure feedwater heaters. For this scheme, the obtained receiver energy efficiency reaches up to 94.1 % and the maximum reduction in Instantaneous Gas fuel consumption is about 10.1 % with a solar-electricity improvement of about 21.6 % over the design case.
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Advantages of Integration Molten Salt Cavity Tubular Solar Central Receiver to the Boiler of Existing Gas-Fuelled Conventional Steam Power
2013Co-Authors: Mahmood S Jamel, Abd A Rahman, A H ShamsuddinAbstract:Abstract: This paper introduces a new method to integrate the economizer of the AL-Hartha steam plant located in Basra, Iraq, using a molten salt cavity tubular solar central receiver (SCR). Cycle Tempo is used to simulate the existing natural Gas-fuelled conventional steam power cycle with consideration of the heat and pressure losses. The heliostat field and the central receiver subsystems are coded using MATLAB. The model couples the heat balance with the temperature computation of the receiver walls for calculation and analysis of the thermal losses. The proposed modified codes are capable of calculating heat losses, evaluating the integrated power plant and satisfying a wide range of SCRs. The results are verified against plant data and previous works in the literature and good agreement is obtained. The results show the potential of using a molten salt cavity tubular SCR for low-range temperature in boiling process in the plant boiler, the economizer part. It is observed that the obtained receiver energy efficiency can reaches up to 94.1% and the maximum reduction in Instantaneous Gas fuel consumption is about 9.1%
Mahmood S Jamel - One of the best experts on this subject based on the ideXlab platform.
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Repowering of existing AL-Hartha Gas-fuelled conventional steam power plant with molten salt cavity tubular solar central receiver
Clean Technologies and Environmental Policy, 2014Co-Authors: Mahmood S Jamel, A. Abd Rahman, A H ShamsuddinAbstract:This paper introduces a new method to repower the existing equipment of the AL-Hartha steam plant located in Basra, Iraq, using a molten salt cavity tubular solar central receiver (SCR). Cycle Tempo is used to simulate the existing natural Gas-fuelled conventional steam power cycle with consideration of the heat and pressure losses. The heliostat field and the central receiver subsystems are coded using MATLAB. The model couples the heat balance with the temperature computation of the receiver walls for calculation and analysis of the thermal losses. The proposed modified codes are capable of calculating heat losses, evaluating the integrated power plant and satisfying a wide range of SCRs. The results are verified against plant data and previous works in the literature and good agreement is obtained. The results show the potential of using a molten salt cavity tubular SCR for low-range temperature feedwater preheating, as well as the optimum scheme for the integration of the existing plant with an SCR. It is observed that the maximum improvement for the existing AL-Hartha steam plant and the integrated molten salt cavity tubular SCR is obtained by substituting the bleed steam in all the high-pressure feedwater heaters. For this scheme, the obtained receiver energy efficiency reaches up to 94.1 % and the maximum reduction in Instantaneous Gas fuel consumption is about 10.1 % with a solar-electricity improvement of about 21.6 % over the design case.
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Advantages of Integration Molten Salt Cavity Tubular Solar Central Receiver to the Boiler of Existing Gas-Fuelled Conventional Steam Power
2013Co-Authors: Mahmood S Jamel, Abd A Rahman, A H ShamsuddinAbstract:Abstract: This paper introduces a new method to integrate the economizer of the AL-Hartha steam plant located in Basra, Iraq, using a molten salt cavity tubular solar central receiver (SCR). Cycle Tempo is used to simulate the existing natural Gas-fuelled conventional steam power cycle with consideration of the heat and pressure losses. The heliostat field and the central receiver subsystems are coded using MATLAB. The model couples the heat balance with the temperature computation of the receiver walls for calculation and analysis of the thermal losses. The proposed modified codes are capable of calculating heat losses, evaluating the integrated power plant and satisfying a wide range of SCRs. The results are verified against plant data and previous works in the literature and good agreement is obtained. The results show the potential of using a molten salt cavity tubular SCR for low-range temperature in boiling process in the plant boiler, the economizer part. It is observed that the obtained receiver energy efficiency can reaches up to 94.1% and the maximum reduction in Instantaneous Gas fuel consumption is about 9.1%
Horstmichael Prasser - One of the best experts on this subject based on the ideXlab platform.
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Signal response of wire-mesh sensors to an idealized bubbly flow
Nuclear Engineering and Design, 2018Co-Authors: Horstmichael Prasser, Richard HäfeliAbstract:Abstract Wire-mesh sensors are widely used to characterize Gas-liquid two-phase flows and single-phase mixing processes. The geometry of the electrode grids and the way of the signal readout generates a three-dimensional electrical field in the vicinity of the electrode wires. Resulting electrical currents at the receiver electrodes, representing the primary measuring information, are calculated by a three-dimensional potential field simulation within the sensitive volume formed by the electrode wires, whereas bubbles are taken into account as simplified, spherical or elliptical objects placed at different locations in the calculation domain. The response of the sensor to the passage of such synthetic bubbles is studied. A significant deviation from the linear dependency between the received current and the local Instantaneous Gas fraction is found. Overshoots of the current above the reference value obtained by calibration in plain liquid occur. Furthermore, the response of the sensor depends on the axial distance between the transmitter and the receiver electrode grids. Swarms of bubbles of small size passing through the grids of the wire-mesh sensor lead to an average decrease of the current which can be described by the average conductivity of an emulsion according to Maxwell.
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evolution of interfacial area concentration in a vertical air water flow measured by wire mesh sensors
Nuclear Engineering and Design, 2007Co-Authors: Horstmichael PrasserAbstract:Abstract An application of wire–mesh sensors to obtain the interfacial area concentration in vertical pipes is presented as an alternative to the widely used multiple-tip electrical or optical fibre probes. The measuring data of a mesh sensor consists of a three-dimensional matrix of local Instantaneous Gas fractions measured at each crossing point of the wires and recorded as a time sequence. Bubbles are clearly distinguishable in this data matrix, since they represent regions of interconnected elements containing the Gaseous phase. The method to deduce the interfacial area concentration from this data is based on a full reconstruction of the Gas–liquid interface, where the interfacial area of each bubble is recovered as the sum of the surface area of all surface elements belonging to the given bubble. The new method can be applied to large bubbles with an arbitrary shape. To study the change of the interfacial area concentration along the pipe the distance between sensor and Gas injection was varied. The axial development of the interfacial area density measured in the test pipe of 195.3 mm inner diameter was compared to the measurements carried out by Sun et al. [Sun, X., Smith, T., Kim, S., Ishii, M., Uhle, J., 2002. Interfacial area of bubbly flow in a relatively large diameter pipe. Exp. Thermal Fluid Sci. 27, 97–109] in a pipe of 101.6 mm diameter, which is the largest pipe for which interfacial area densities are presented in literature. An acceptable agreement was found, whereas deviations are consistent with the differences in the boundary conditions of both experiments.
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evolution of the structure of a Gas liquid two phase flow in a large vertical pipe
Nuclear Engineering and Design, 2007Co-Authors: Horstmichael Prasser, Dirk Lucas, Matthias Beyer, Helmar Carl, Sabine Gregor, Heiko Pietruske, Peter Schutz, Frankpeter WeissAbstract:The evolution of the structure of a Gas–liquid flow in a large vertical pipe of 195 mm inner diameter was investigated at the TOPFLOW test facility in Rossendorf. Wire-mesh sensors were used to measure sequences of two-dimensional distributions of local Instantaneous Gas fraction within the complete pipe cross-section. The sensors own a resolution of 3 mm at a frequency of 2500 Hz. Superficial velocities were varied in a range covering flow regimes from bubbly to churn-turbulent flow. The distance between the Gas injection and the sensor position was changed using a so-called variable Gas injection system. It consists of six Gas injection units, each equipped with three rings of injection orifices in the pipe wall (orifice diameter: 1 and 4 mm), which are fed from ring chambers. The Gas flow towards these distributor chambers is individually controlled by valves. Measured bubble-size resolved radial Gas fraction profiles reveal differences in the lateral migration of bubbles of different size starting from the injection at the wall. The evolution of bubble-size distributions allows to study bubble coalescence and break-up. The influence of the physical properties of the fluid was studied by comparing cold air–water experiments with steam–water tests at 65 bar.
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evolution of the two phase flow in a vertical tube decomposition of Gas fraction profiles according to bubble size classes using wire mesh sensors
International Journal of Thermal Sciences, 2002Co-Authors: Horstmichael Prasser, Eckhard Krepper, Dirk LucasAbstract:The wire-mesh sensor developed by the Forschungszentrum Rossendorf produces sequences of Instantaneous Gas fraction distributions in a cross section with a time resolution of 1200 frames per second and a spatial resolution of about 2–3 mm. At moderate flow velocities (up to 1–2 m·s−1), bubble size distributions can be obtained, since each individual bubble is mapped in several successive distributions. The method was used to study the evolution of the bubble size distribution in a vertical two-phase flow. For this purpose, the sensor was placed downstream of an air injector, the distance between air injection and sensor was varied. The bubble identification algorithm allows to select bubbles of a given range of the effective diameter and to calculate partial Gas fraction profiles for this diameter range. In this way, the different behaviour of small and large bubbles in respect to the action of the lift force was observed in a mixture of small and large bubbles.
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bubble size measurement using wire mesh sensors
Flow Measurement and Instrumentation, 2001Co-Authors: Horstmichael Prasser, D Scholz, C ZippeAbstract:Abstract A wire-mesh sensor with a time resolution of 1.2 kHz was used to measure bubble size distributions in a Gas-liquid flow. It is designed for a pipe of 51.2 mm diameter and consists of two electrode grids with 16 electrodes each, put in the flow direction behind each other. The local Instantaneous electrical conductivity is directly measured between all pairs of crossing wires, a tomographic image reconstruction is not necessary. The resulting 16 × 16 sensitive points are equally distributed over the cross section. This resolution is sufficient to detect individual bubbles, which are imaged in several successive frames during their transition through the measuring plane. To investigate the influence on bubbles, a model of the sensor was tested in a transparent channel with a rectangular cross section of 50 × 50 mm at liquid velocities between 0 and 0.8 m/s. A comparison with high-speed video observations has shown that the sensor causes a significant fragmentation of the bubbles. Nevertheless, the measured signals still represent the structure of the two-phase flow before it is disturbed by the sensor. Bubble sizes can therefore be determined by integrating local Instantaneous Gas fractions over an area of the measuring points occupied by the bubble. Bubble size distributions are obtained by analysing large assemblies of bubbles. The method was applied to study the formation of slug flow along a vertical tube. The bubble size distributions obtained show the effect of coalescence as well as bubble fragmentation.
Jiarong Hong - One of the best experts on this subject based on the ideXlab platform.
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a hybrid image processing method for measuring 3d bubble distribution using digital inline holography
Chemical Engineering Science, 2019Co-Authors: Siyao Shao, Jiarong HongAbstract:Abstract The paper presents a hybrid bubble hologram processing approach for measuring the size and 3D distribution of bubbles over a wide range of size and shape. The proposed method consists of five major steps, including image enhancement, digital reconstruction, small bubble segmentation, large bubble/cluster segmentation, and post-processing. Two different segmentation approaches are proposed to extract the size and the location of bubbles in different size ranges from the 3D reconstructed optical field. Specifically, a small bubble is segmented based on the presence of the prominent intensity minimum in its longitudinal intensity profile, and its depth is determined by the location of the minimum. In contrast, a large bubble/cluster is segmented using a modified watershed segmentation algorithm and its depth is measured through a wavelet-based focus metric. Our processing approach also determines the inclination angle of a large bubble with respect to the hologram recording plane based on the depth variation along its edge on the plane. The accuracy of our processing approach on the measurements of object size and 3D distributions are assessed through synthetic bubble holograms and oil droplet holograms from an experiment separately. In addition, we evaluate the ability of this algorithm to estimate the bubble inclination with respect to the hologram recording plane through measuring a 3D-printed physical target of pillars with different inclination angles. The holographic measurement technique is further implemented to capture the fluctuation of Instantaneous Gas leakage rate from a ventilated supercavity generated in a water tunnel experiment. Overall, our paper introduces an inexpensive and compact solution for high resolution characterization of bubbles and other particles in multiphase flows from a broad range of applications.
Dirk Lucas - One of the best experts on this subject based on the ideXlab platform.
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evolution of the structure of a Gas liquid two phase flow in a large vertical pipe
Nuclear Engineering and Design, 2007Co-Authors: Horstmichael Prasser, Dirk Lucas, Matthias Beyer, Helmar Carl, Sabine Gregor, Heiko Pietruske, Peter Schutz, Frankpeter WeissAbstract:The evolution of the structure of a Gas–liquid flow in a large vertical pipe of 195 mm inner diameter was investigated at the TOPFLOW test facility in Rossendorf. Wire-mesh sensors were used to measure sequences of two-dimensional distributions of local Instantaneous Gas fraction within the complete pipe cross-section. The sensors own a resolution of 3 mm at a frequency of 2500 Hz. Superficial velocities were varied in a range covering flow regimes from bubbly to churn-turbulent flow. The distance between the Gas injection and the sensor position was changed using a so-called variable Gas injection system. It consists of six Gas injection units, each equipped with three rings of injection orifices in the pipe wall (orifice diameter: 1 and 4 mm), which are fed from ring chambers. The Gas flow towards these distributor chambers is individually controlled by valves. Measured bubble-size resolved radial Gas fraction profiles reveal differences in the lateral migration of bubbles of different size starting from the injection at the wall. The evolution of bubble-size distributions allows to study bubble coalescence and break-up. The influence of the physical properties of the fluid was studied by comparing cold air–water experiments with steam–water tests at 65 bar.
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evolution of the two phase flow in a vertical tube decomposition of Gas fraction profiles according to bubble size classes using wire mesh sensors
International Journal of Thermal Sciences, 2002Co-Authors: Horstmichael Prasser, Eckhard Krepper, Dirk LucasAbstract:The wire-mesh sensor developed by the Forschungszentrum Rossendorf produces sequences of Instantaneous Gas fraction distributions in a cross section with a time resolution of 1200 frames per second and a spatial resolution of about 2–3 mm. At moderate flow velocities (up to 1–2 m·s−1), bubble size distributions can be obtained, since each individual bubble is mapped in several successive distributions. The method was used to study the evolution of the bubble size distribution in a vertical two-phase flow. For this purpose, the sensor was placed downstream of an air injector, the distance between air injection and sensor was varied. The bubble identification algorithm allows to select bubbles of a given range of the effective diameter and to calculate partial Gas fraction profiles for this diameter range. In this way, the different behaviour of small and large bubbles in respect to the action of the lift force was observed in a mixture of small and large bubbles.