Search results

1 – 10 of over 73000
To view the access options for this content please click here
Article

Mohammad Asaduzzaman Chowdhury, Dewan Muhammad Nuruzzaman, Khaled Khalil and Mohammad Lutfar Rahaman

Solid thin films have been deposited on stainless steel 314 (SS 314) substrates in a chemical vapor deposition (CVD) reactor at different flow rates of natural gas mostly…

Abstract

Purpose

Solid thin films have been deposited on stainless steel 314 (SS 314) substrates in a chemical vapor deposition (CVD) reactor at different flow rates of natural gas mostly methane (CH4). The purpose of this paper was to investigate experimentally the variation of thin film deposition rate with the variation of gas flow rate.

Design/methodology/approach

During experiment, the effect of gap between activation heater and substrate on the deposition rate has also been observed. To do so, a hot filament thermal CVD unit is used. The flow rate of natural gas varies from 0.5 to 2 l/min at normal temperature and pressure and the gap between activation heater and substrate varies from 4 to 6.5 mm.

Findings

Results show that deposition rate on SS 314 increases with the increase of gas flow rate. It is also seen that deposition rate increases with the decrease of gap between activation heater and substrate within the observed range. These results are analyzed by dimensional analysis to correlate the deposition rate with gas flow rate, surface roughness and film thickness. In addition, friction coefficient and wear rate of SS 314 sliding against SS 304 under different normal loads are also investigated before and after deposition. The obtained results reveal that the values of friction coefficient and wear rate are lower after deposition than that of before deposition.

Originality/value

In this study, thin film deposition rate on SS 314 was investigated using CVD. The obtained results were analyzed by dimensional analysis to correlate the deposition rate with gas flow rate, surface roughness and film thickness. The friction coefficient and wear rate of SS 314 were also examined before and after deposition.

Details

Industrial Lubrication and Tribology, vol. 63 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

To view the access options for this content please click here
Book part

Mohammad Shamsuddoha

Contemporary literature reveals that, to date, the poultry livestock sector has not received sufficient research attention. This particular industry suffers from…

Abstract

Contemporary literature reveals that, to date, the poultry livestock sector has not received sufficient research attention. This particular industry suffers from unstructured supply chain practices, lack of awareness of the implications of the sustainability concept and failure to recycle poultry wastes. The current research thus attempts to develop an integrated supply chain model in the context of poultry industry in Bangladesh. The study considers both sustainability and supply chain issues in order to incorporate them in the poultry supply chain. By placing the forward and reverse supply chains in a single framework, existing problems can be resolved to gain economic, social and environmental benefits, which will be more sustainable than the present practices.

The theoretical underpinning of this research is ‘sustainability’ and the ‘supply chain processes’ in order to examine possible improvements in the poultry production process along with waste management. The research adopts the positivist paradigm and ‘design science’ methods with the support of system dynamics (SD) and the case study methods. Initially, a mental model is developed followed by the causal loop diagram based on in-depth interviews, focus group discussions and observation techniques. The causal model helps to understand the linkages between the associated variables for each issue. Finally, the causal loop diagram is transformed into a stock and flow (quantitative) model, which is a prerequisite for SD-based simulation modelling. A decision support system (DSS) is then developed to analyse the complex decision-making process along the supply chains.

The findings reveal that integration of the supply chain can bring economic, social and environmental sustainability along with a structured production process. It is also observed that the poultry industry can apply the model outcomes in the real-life practices with minor adjustments. This present research has both theoretical and practical implications. The proposed model’s unique characteristics in mitigating the existing problems are supported by the sustainability and supply chain theories. As for practical implications, the poultry industry in Bangladesh can follow the proposed supply chain structure (as par the research model) and test various policies via simulation prior to its application. Positive outcomes of the simulation study may provide enough confidence to implement the desired changes within the industry and their supply chain networks.

Details

Sustaining Competitive Advantage Via Business Intelligence, Knowledge Management, and System Dynamics
Type: Book
ISBN: 978-1-78560-707-3

Keywords

To view the access options for this content please click here
Article

Xiaoqi Jia, Sheng Yuan, Zuchao Zhu and Baoling Cui

Instantaneous radial force induced from unsteady flow will intensify vibration noise of the centrifugal pump, especially under off-design working conditions, which will…

Abstract

Purpose

Instantaneous radial force induced from unsteady flow will intensify vibration noise of the centrifugal pump, especially under off-design working conditions, which will affect safety reliability of pump operation in severe cases. This paper aims to conduct unsteady numerical computation on one centrifugal pump; thus, unsteady fluid radial force upon the impeller and volute is obtained, so as to study the evolution law of instantaneous radial force, the internal relationship between radial force and pressure pulsation, the relationship among each composition of radial force that the impeller received and the influence of leakage rate of front and back chamber on radial force.

Design/methodology/approach

The unsteady numerical simulation with SST k-ω turbulence model was carried out for a low specific-speed centrifugal pump using computational fluid dynamics codes FLUENT. The performance tests and pressure tests were conducted by a closed loop system. The performance curves and the pressure distribution from numerical simulation agree with that of the experiment conducted. The unsteady pressure distributions and the instantaneous radial forces induced from unsteady flow were analyzed under different flow rates. Contribution degrees of three components of the radial force on the impeller and the relation between the radial force and leakage rate were analyzed.

Findings

Radial force on the volute and pressure pulsation on the volute wall have the same distribution tendency, but in contrast to the distribution trend of the radial force on the impeller. In the component of radial force that the impeller received, radial force on the blade accounts for the main position. With the decrease of flow rate, ratio of the radial force on front and back casings will be increased; under large flow rate, vortex and flow blockage at volute section will enhance the pressure and radial force fluctuation greatly, and the pulsation degree may be much more intense than that of a smaller flow rate.

Originality/value

This paper revealed the relation of the radial force and the pressure pulsation. Meanwhile, contribution degrees of three components of the radial force on the impeller under different working conditions as well as the relation between the radial force and leakage rate of front and rear chambers were analyzed.

Details

Engineering Computations, vol. 37 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article

Zhengying Wei, Yiping Tang, Wanhua Zhao and Bingheng Lu

The paper aims to summarize the design theory for labyrinth channels of water saving emitters.

Abstract

Purpose

The paper aims to summarize the design theory for labyrinth channels of water saving emitters.

Design/methodology/approach

On the basis of extracting the structural parameters of labyrinth channels in water saving emitters, the hydraulic performance experiments on the integral emitters fabricated with higher resolution rapid prototyping technology are performed. Then, using multivariable linear regression, formulas of pressure versus flow rate and regression plots for different emitters are induced.

Findings

The formulas of flow rate versus structural parameters are summarized based on the trapezoid‐type channel unit, and verified through experiments. The relationships between flow rate, pressure and structural parameters of channels are established.

Research limitations/implications

The effect of emitter fabrication error on the flow rate is analyzed, which provides a basis for parameterized structural design and accuracy control in the fabrication of future emitters.

Practical implications

The QHn relationship equations are used to design emitters which have flowrate errors under both high‐ and low‐water pressure of less than 4 percent. So the QHn relationship equation of the emitter is well proven and accurate which can guide the design for the structure of emitters with trapezoid labyrinth channels.

Originality/value

In this paper, a new stereolithography system has been used to fabricate accurately a drip irrigation emitter with a complex microstructure, which cannot be obtained with conventional RP or other manufacturing processes. Compared to other manufacturing process, this new technique has higher manufacturing accuracy and can reduce the manufacturing cost and time. Furthermore, a design theory for labyrinth channels of water saving emitters is established.

Details

Rapid Prototyping Journal, vol. 13 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article

Mehdi Mosharaf-Dehkordi and Hamid Reza Ghafouri

The purpose of this paper is to present detailed algorithms for simulation of individual and group control of production wells in hydrocarbon reservoirs which are…

Abstract

Purpose

The purpose of this paper is to present detailed algorithms for simulation of individual and group control of production wells in hydrocarbon reservoirs which are implemented in a finite volume-based reservoir simulator.

Design/methodology/approach

The algorithm for individual control is described for the multi-lateral multi-connection ones based on the multi-segment model considering cross-flow. Moreover, a general group control algorithm is proposed which can be coupled with any well model that can handle a constraint and returns the flow rates. The performance of oil production process based on the group control criteria is investigated and compared for various cases.

Findings

The proposed algorithm for group control of production wells is a non-optimization iterative scheme converging within a few number of iterations. The numerical results of many computer runs indicate that the nominal power of the production wells, in general, is the best group control criterion for the proposed algorithm. The production well group control with a proper criterion can generally improve the oil recovery process at negligible computational costs when compared with individual control of production wells.

Research/limitations/implications

Although the group control algorithm is implemented for both production and injection wells in the developed simulator, the numerical algorithm is here described only for production wells to provide more details.

Practical/implications

The proposed algorithm can be coupled with any well model providing the fluid flow rates and can be efficiently used for group control of production wells. In addition, the calculated flow rates of the production wells based on the group control algorithm can be used as candidate solutions for the optimizer in the simulation-optimization models. It may reduce the total number of iterations and consequently the computational cost of the simulation-optimization models for the well control problem.

Originality/value

A complete and detailed description of ingredients of an efficient well group control algorithm for the hydrocarbon reservoir is presented. Five group control criteria are extracted from the physical, geometrical and operating conditions of the wells/reservoir. These are the target rate, weighted potential, ultimate rate and introduced nominal power of the production wells. The performance of the group control of production wells with different group control criteria is compared in three different oil production scenarios from a black-oil and highly heterogeneous reservoir.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 11
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article

Yuanpeng Cheng, Yu Bai, Zili Li and JianGuo Liu

The purpose of this paper was to investigate the corrosion behavior of X65 steel in the CO2/oil/water environment using mass loss method, potentiodynamic polarization…

Abstract

Purpose

The purpose of this paper was to investigate the corrosion behavior of X65 steel in the CO2/oil/water environment using mass loss method, potentiodynamic polarization technique and characterization of the corroded surface techniques.

Design/methodology/approach

The weight loss analysis, electrochemical study and surface investigation were carried out on X65 steel that had been immersed in the CO2/oil/water corrosive medium to understand the corrosion behavior of gathering pipeline steel. The weight loss tests were carried out in a 3L autoclave, and effects of flow velocity, CO2 partial pressure and water cut on the CO2 corrosion rate of X65 steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature of 60°C and CO2 partial pressure of 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using X-ray diffraction.

Findings

The results showed that corrosion rates of X65 steel both increased at first and then decreased with the increase of flow velocity and CO2 partial pressure, and there were critical velocity and critical pressure in the simulated corrosive environment, below the critical value, the corrosion products formed on the steel surface were loose, porous and unstable, higher than the critical value, the corrosion product ?lms were dense, strong adhesion, and had a certain protective effect. Meanwhile, when the flow velocity exceeded the critical value, oil film could be adsorbed on the steel surface more evenly, corrosion reaction active points were reduced and the steel matrix was protected from being corroded and crude oil played a role of inhibitor, thus it influenced the corrosion rate. Above the critical CO2 partial pressure, the solubility of CO2 in crude oil increased, the viscosity of crude oil decreased and its fluidity became better, so that the probability of oil film adsorption increased, these factors led to the corrosion inhibition of X65 steel reinforced. The corrosion characteristics of gathering pipeline steel in the corrosive environment containing CO2 would change due to the presence of crude oil.

Originality/value

The results can be helpful in selecting the suitable corrosion inhibitors and targeted anti-corrosion measures for CO2/oil/water corrosive environment.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

To view the access options for this content please click here
Article

Pekka Ilmakunnas and Mika Maliranta

Job and worker flows in the Finnish business sector are studied during a deep recession in the early 1990s. The data set covers effectively the whole work force. The gross…

Abstract

Job and worker flows in the Finnish business sector are studied during a deep recession in the early 1990s. The data set covers effectively the whole work force. The gross job and worker flow rates are fairly high. The evidence suggests that the adjustment of labor input has happened through a reduced hiring rate rather than through an increased separation rate. However, during the recession the group of declining plants included more and larger plants than before, which led to reduced employment. Excess worker turnover (churning) and excess job reallocation have been low during the recession. The evidence of the countercyclicality of job reallocation is mixed. The flows are calculated both for the whole business sector, and for seven main industries. Services have clearly higher flow rates than manufacturing, but the cyclical changes in the flows are fairly similar in all industries. To test the sensitivity of the results to data sources, job flows are calculated from three different statistics.

Details

International Journal of Manpower, vol. 24 no. 3
Type: Research Article
ISSN: 0143-7720

Keywords

To view the access options for this content please click here
Article

Jian Song, Zhiming Gao, Chenxi Liu and Wenbin Hu

This paper aims to study the effect of flow rate (0.42∼2.09 m/s) on the corrosion behavior of WB36CN1 steel pipe in the simulated secondary circuit water environment…

Abstract

Purpose

This paper aims to study the effect of flow rate (0.42∼2.09 m/s) on the corrosion behavior of WB36CN1 steel pipe in the simulated secondary circuit water environment (170°C, 6 mg/L ethanolamine + 100 µg/L NaCl), for which an autoclave was used to simulate the secondary circuit environment for carrying out related experiments.

Design/methodology/approach

The corrosion behaviors were studied by electrochemical methods, morphological observations and elemental analysis.

Findings

As flow rate increases, the amplitude of the current noise fluctuates increased, noise resistance Rn and spectral noise resistance Rsn decreased, the shear stress on the surface of WB36CN1 steel increases, the oxygen content on the surface decreases, the roughness becomes smaller. Meanwhile, the energy of energy distribution plot is concentrated at high frequencies under the three flow conditions, the slopes of current power spectral density curve approach 0 db/decade. This means that the oxide on the surface becomes less and corrosion rate increases with increasing flow rate. The corrosion type of WB36CN1 steel was uniform corrosion; the degree of uniform corrosion is higher at high flow rate.

Originality/value

The effect of flow rate on the corrosion behavior of WB36CN1 steel pipe in the secondary circuit water environment was studied by using electrochemical methods in the laboratory. The effect mechanism of flow rate for corrosion behavior was obtained.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

To view the access options for this content please click here
Article

Chao Wang, Heyang Yu, Ni Zhan, Xubing Kang and Jingyu Zhang

The purpose of this paper is to develop a new vibration probe sensor for measurement of particle mass flow rate in gas–solid two phase flow.

Abstract

Purpose

The purpose of this paper is to develop a new vibration probe sensor for measurement of particle mass flow rate in gas–solid two phase flow.

Design/methodology/approach

A new vibration probe sensor based on polyvinylidene fluoride (PVDF) piezoelectric film is designed. The particle impact model according to Hertz contacting theory is presented. The average amplitude, standard deviation and spectral peak at the natural frequency of the probe (21.2 kHz) of the signals acquired through experiments are chosen as characteristic quantities for further analysis.

Findings

Through experimental study of relation between three characteristic quantities and the mass flow rate and air flow velocity, a good regularity is found in the average amplitude and the spectral peaks at natural frequency of the probe. According to the particle impact model, the structure of quantitative model is built and parameters of two models are calculated from experimental data. Additionally, tests are made to estimate mass flow rate. The average errors are 5.85 and 4.26 per cent, while the maximum errors are 10.81 and 8.65 per cent. The spectral peak at natural frequency of the probe is more applicable for mass flow rate measurement.

Practical implications

The sensor designed and the quantitative models established may be used in dilute phase pneumatic conveying lines of coal-fired power plants, cement manufacturing facilities and so on.

Originality/value

First, the new sensor is designed and the quantitative models are established. Second, the spectral peak at natural frequency of the probe is found that can be used for measurement of mass flow rate.

Details

Sensor Review, vol. 36 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

To view the access options for this content please click here
Article

Seyed Ali Atyabi, Ebrahim Afshari and Mohammad Yaghoub Abdollahzadeh Jamalabadi

In this paper, a single module of cross-flow membrane humidifier is evaluated as a three-dimensional multiphase model. The purpose of this paper is to analyze the effect…

Abstract

Purpose

In this paper, a single module of cross-flow membrane humidifier is evaluated as a three-dimensional multiphase model. The purpose of this paper is to analyze the effect of volume flow rate, dry temperature, dew point wet temperature and porosity of gas diffusion layer on the humidifier performance.

Design/methodology/approach

In this study, one set of coupled equations are continuity, momentum, species and energy conservation is considered. The numerical code is benchmarked by the comparison of numerical results with experimental data of Hwang et al.

Findings

The results reveal that the transfer rate of water vapor and dew point approach temperature (DPAT) increase by increasing the volume flow rate. Also, it is found that the water recovery ratio (WRR) and relative humidity (RH) decrease with increasing volume flow rate. In addition, all mixed results decrease with increasing dry side temperature especially at high volume flow rates and this trend in high volume flow rates is more sensible. Although the transfer rate of water vapor and DPAT increases with increasing the wet inlet temperature, WRR and RH reduce. Increasing dew point temperature effect is more sensible at the wet side is compared with the dry side. The humidification performance will be enhanced with increasing diffusion layer porosity by increasing the wet inlet dew point temperature, but has no meaningful effect on other operating parameters. The pressure drop along humidifier gas channels increases with rising flow rate, consequently, the required power of membrane humidifier will enhance.

Originality/value

According to previous studies, the three-dimensional numerical multiphase model of cross-flow membrane humidifier has not been developed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

1 – 10 of over 73000