Pravin H. Yadav, Sandeep R. Desai and Dillip Kumar Mohanty
Predicting the critical velocity is crucial at the instability threshold for shell and tube heat exchangers in order to prevent tube failure due to vibrations. In this study, the…
Abstract
Purpose
Predicting the critical velocity is crucial at the instability threshold for shell and tube heat exchangers in order to prevent tube failure due to vibrations. In this study, the vibration response of an aluminum tube bundle subjected to water cross flow was analyzed experimentally. Aluminum tubes are preferred over steel tubes because of aluminum tubes' excellent corrosion resistance, ease of manufacture, and high thermal efficiency.
Design/methodology/approach
The fluid elastic instability and vortex shedding mechanisms in a finned tube array of aluminum tubes with a base tube diameter of 19.05 mm and pitch of 34 mm were investigated. The current study considers parallel triangular finned tube arrays with fin heights of 3 mm and 6 mm with a uniform fin thickness and fin pitch. The plain tube array was tested to compare the finned tube array results. The tube vibration response was measured using an accelerometer mounted on the middle tube of the third row. In order to define the fluid elastic instability behavior of various tube arrays, the critical velocity at the instability threshold is measured. By finding the Strouhal number at the small peaks before instability, the vortex shedding behavior of the tube arrays is examined.
Findings
The results reveal that the critical velocity at instability for coarse finned tube arrays increases as the fin height increases. The effect of the tube material is evaluated by comparing the results with those previously reported for parallel triangular tube arrays made of steel. Finally, the occurrence of vortex shedding in a tube array is confirmed based on the Reynolds number and Strouhal number relationship. The instability constant K for the plain tube array of steel and aluminum material are 4.97 and 4.87, respectively.
Originality/value
This paper provides the research findings on the effect of fin height on coarse density finned tube array. This will add substantial knowledge to the literature in the field of fluid elastic instability and vortex shedding, which is needed for the safe functioning of shell and tube heat exchangers.
Details
Keywords
Pravin Hindurao Yadav, Sandeep R. Desai and Dillip Kumar Mohanty
The purpose of this paper is to present investigations on the significant influence of the tube material and fin density on fluid elastic instability and vortex shedding in a…
Abstract
Purpose
The purpose of this paper is to present investigations on the significant influence of the tube material and fin density on fluid elastic instability and vortex shedding in a parallel triangular finned tube array subjected to water cross flow.
Design/methodology/approach
The experiment was conducted on finned tube arrays with a fin height of 6 mm and fin density of 3 fins per inch (fpi) and 9 fpi. A dedicated setup has been developed to examine fluid elastic instability and vortex shedding. Nine parallel triangular tube arrays with a pitch to tube diameter ratio of 1.78 were considered. The plain tube arrays, coarse finned tube arrays and fine finned tube arrays each of steel, copper and aluminium materials were tested. Plain tube arrays were tested to compare the results of the finned tube arrays having an effective tube diameter same as that of the plain tube.
Findings
A significant effect of fin density and tube material with a variable mass damping parameter was observed on the instability threshold. In the parallel triangular finned tube array subjected to water cross flow, a delay in the instability threshold was observed with an increase in fin density. For steel and aluminium tube arrays, the natural frequency is 9.77 Hz and 10.38 Hz, which is close to each other, whereas natural frequency of the copper tubes is 7.40 Hz. The Connors’ stability constant K for steel and aluminium tube arrays is 4.78 and 4.87, respectively, whereas it is 5.76 for copper tube arrays, which increases considerably compared to aluminum and steel tube arrays. The existence of vortex shedding is confirmed by comparing experimental results with Owen’s hypothesis and the Strouhal number and Reynolds number relationship.
Originality/value
This paper’s results contribute to understand the effect of tube materials and fin density on fluid elastic instability threshold of finned tube arrays subjected to water cross flow.
Details
Keywords
Pravin Hindurao Yadav and Dillip kumar Mohanty
This paper aims to analyze the effect of fin geometry on mechanisms of flow induced vibration. Finned tube arrays are used in a heat exchanger to increase its efficiency…
Abstract
Purpose
This paper aims to analyze the effect of fin geometry on mechanisms of flow induced vibration. Finned tube arrays are used in a heat exchanger to increase its efficiency. Therefore, it is necessary to investigate the effect of geometric parameters of the fin fluid elastic instability and vortex shedding. In this paper, the effect of fin height, fin density and tube pitch ratio for parallel triangular tube array on fluid elastic instability and vortex shedding is analyzed.
Design/methodology/approach
Experimental analysis was carried out on a parallel triangular finned tube array with a pitch ratio of 1.79 subjected to water crossflow. The experimentation aims to study fluid elastic instability and vortex-induced vibration mechanism responsible for flow induced vibration for finned tube array. A fully flexible finned tube array of the copper tube was used with its base diameter of 19.05 mm and thickness of 2 mm. Over the tube surface, crimped fins of height 6 mm and the same material are welded spirally with fin density 8.47 mm and 2.82 mm. Experimental analysis was carried out on a test setup developed for the same. The results obtained for the finned tube array were compared with those for the plain tube array with the same base tube diameter.
Findings
For parallel triangular tube array of copper material, test results show that critical velocity increases with an increase in fin pitch density for low pitch tube array. Before the occurrence of instability, the rate of growth in tube vibrations is high for plain tubes compared to that with fin tubes. The results based on Owen’s hypothesis show vortex shedding before the occurrence of fluid elastic instability. The effect of fin geometry on vortex-induced forces is analyzed. For the tube array pattern understudy, the values of Conner’s constant K for coarse fin-tube and fine fin tube array are obtained, respectively, 6.14 and 7.25.
Originality/value
This paper fulfills the need for research on the effect of fin geometry on fluid elastic instability and Vortex shedding on a tube array subjected to water cross flow when the pitch ratio is less than two, i.e. with a low pitch ratio.
Details
Keywords
Balaji V., Kaliappan S., Madhuvanesan D.M., Ezhumalai D.S., Boopathi S., Patil Pravin P. and Saiprakash Mani
The purpose of the study is to examine the influence of the corn biofuel on the Jet engine. Each tests were carried out in a small gas turbine setup. The performance…
Abstract
Purpose
The purpose of the study is to examine the influence of the corn biofuel on the Jet engine. Each tests were carried out in a small gas turbine setup. The performance characteristics of thrust, thrust-specific fuel consumption, exhaust gas temperature and emission characteristics of Carbon monoxide(CO), Carbon dioxide (CO2), Oxygen (O2), Unburned hydrocarbons (UHC) and Nitrogen of oxides (NO) emissions were measured and compared with Jet-A fuel to find the suitability of the biofuel used.
Design/methodology/approach
Upgrading and using biofuels in aviation sector have been emerging as a fruitful method to diminish the CO emission into the atmosphere. This research paper explores the possibility of using nanoparticles-enriched bio-oil as a fuel for jet engines. The biofuel taken is corn oil and the added nanoparticles are Al2O3.
Findings
The biofuel blends used are B0 (100% Jet-A fuel), B10 (10 % corn oil biofuel + 90% Jet-A fuel), B20 (20% corn oil biofuel + 80% Jet-A fuel) and B30 (30% corn oil biofuel + 70% Jet-A fuel). All fuel blends were mixed with the moderate dosage level of 30 ppm. All tests were conducted at different rpm as 50,000, 60,000, 70,000 and 80,000 rpm.
Originality/value
The results proved that within the lower limit, use of biofuel increased the performance characteristics and reduced the emission characteristics except the emission of NO. The moderate-level biofuel with Jet-A fuel showed the equally better performance to the neat Jet-A fuel.
Details
Keywords
Pankaj Mandpe, Bala Prabhakar, Hunny Gupta and Pravin Shende
The present study aims to summarize different non-invasive techniques for continuous glucose monitoring (CGM) in diabetic patients using glucose-oxidase biosensors. In diabetic…
Abstract
Purpose
The present study aims to summarize different non-invasive techniques for continuous glucose monitoring (CGM) in diabetic patients using glucose-oxidase biosensors. In diabetic patients, the self-monitoring of blood glucose (BG) levels through minimally invasive techniques provides a quick method of measuring their BG concentration, unlike conventional laboratory measurements. The drawbacks of minimally invasive techniques include physical pain, anxiety and reduced patient compliance. To overcome these limitations, researchers shifted their attention towards the development of a pain-free and non-invasive glucose monitoring system, which showed encouraging results.
Design/methodology/approach
This study reviews the development of minimally and non-invasive method for continuous glucose level monitoring in diabetic or hyperglycemic patients. Specifically, glucose monitoring using non-invasive techniques, such as spectroscopy-based methods, polarimetry, fluorescence, electromagnetic variations, transdermal extraction-based methods and using body fluids, has been discussed. The various strategies adopted for improving the overall specificity and performance of biosensors are discussed.
Findings
In conclusion, the technology of glucose oxidase-based biosensors for glucose level monitoring is becoming a strong competitor, probably because of high specificity and selectivity, low cost and increased patient compliance. Many industries currently working in this field include Google, Novartis and Microsoft, which demonstrates the significance and strong market potential of self-monitored glucose-oxidase-based biosensors in the near future.
Originality/value
This review paper summarizes comprehensive strategies for continuous glucose monitoring (CGM) in diabetic patients using non-invasive glucose-oxidase biosensors. Non-invasive techniques received significant research interest because of high sensitivity and better patient compliance, unlike invasive ones. Although the results from these innovative devices require frequent calibration against direct BG data, they might be a preferable candidate for future CGM. However, the challenges associated with designing accurate level sensors to biomonitor BG data easily and painlessly needs to be addressed.
Pravin Kumar, Ravi Shankar and Surendra S. Yadav
The purpose of this paper is to identify and evaluate the relationships among the flexibility enablers and to prepare a hierarchy of these enablers to know their influences over…
Abstract
Purpose
The purpose of this paper is to identify and evaluate the relationships among the flexibility enablers and to prepare a hierarchy of these enablers to know their influences over each other in global supply chain. The framework suggests that the priority of enablers in supply chain should be determined on the basis of their driving power and dependency.
Design/methodology/approach
Various enablers used by researchers and practitioners for flexibility management of global supply chain have been identified. These enablers have been classified as strategic, operational and performance‐based enablers. Interpretive structural modeling (ISM) is used to establish mutual relationships among the flexibility enablers and to prepare a hierarchy‐based model.
Findings
It has been observed that some enablers having high‐driving power and low dependency are of strategic importance. These enablers require more attention while other enablers based on operations and performances are dependents of strategic enablers.
Practical implications
The index of enablers based on driving power and dependency provides an insight to supply chain managers to make the entire supply chain highly flexible and help them to respond to global uncertainties.
Originality/value
Presentation of enablers in the form of hierarchy using ISM and ranking them into various driving power and dependent categories is a good effort to make flexible global supply chain.
Details
Keywords
Rajesh Kumar Singh and Pravin Kumar
In complex business environment of today, organizations are trying to be flexible and agile for meeting dynamic demands of customers in terms of product variety, cost cutting and…
Abstract
Purpose
In complex business environment of today, organizations are trying to be flexible and agile for meeting dynamic demands of customers in terms of product variety, cost cutting and decreasing product life cycle. The main purpose of this paper is to identify different attributes of flexibility and to propose an approach for evaluating flexibility index of a supply chain.
Design/methodology/approach
Total 33 factors are identified from the literature and further clustered into six major groups. They are top management commitment, organizational factors, mutual understanding, flow of information, relationship and decision-making and responsiveness. On the basis of these factors, an index has been developed by using graph theory matrix approach to evaluate the flexibility intensity of the supply chain for the firm in consideration.
Findings
The proposed approach has been illustrated in context to an Indian automobile organization, and value of the flexibility index has been evaluated. Framework proposed will help the supply chain managers to evaluate the flexibility index of their respective organizations.
Research limitations/implications
As values taken for different flexibility sub-factors are based on inputs given by managers of case organization, chances of bias may be there. Therefore, a study may be validated with more case studies to validate the proposed framework. Based on the flexibility index, organizations can find their strong and weak areas for strategy development.
Originality/value
A firm can also compare the flexibility index of its own supply chain with other’s supply chain or with the best in the industry for benchmarking purpose. Benchmarking of flexibility will help organizations in developing strategies to compete in dynamic market scenario.
Details
Keywords
Yogesh Kumar Sharma, Sachin Kumar Mangla, Pravin P. Patil and Shaofeng Liu
The food organisations are pushing to adopt circular economy initiatives to enhance economic–ecological–social sustainability of supply chains. The adoption of circular economy…
Abstract
Purpose
The food organisations are pushing to adopt circular economy initiatives to enhance economic–ecological–social sustainability of supply chains. The adoption of circular economy and sustainability aspects is complex from the point of view of developing nations compared to the developed nations. In this sense, the purpose of this paper is to develop a model of the challenges for implementing the successful circular economy-led sustainability concepts in food supply chains in emerging economies, especially in the Indian context.
Design/methodology/approach
The authors recognised 11 circular economy-led sustainability-related challenges and analysed appropriate interactions among the identified challenges. The Delphi method was used for the confirmation of identified challenges. The challenges were identified initially with the help of literature. Interpretive structural modelling method was used for modelling the challenges. In addition, MICMAC analysis was used for classifying the challenges based on their dependence and driving power. A case study of diary food processing company in India was conducted.
Findings
According to the findings, poor government policies, lack of technology and techniques and lack of farmers’ knowledge and awareness come under the driving challenges.
Practical implications
Understanding of circular economy-led sustainability-related challenges would help managers and policy makers in the sustainable management of natural resources in food value chains.
Originality/value
This is one of the initial works conducted on identifying and evaluating the challenges to circular economy-based sustainability aspects in food value chains.
Details
Keywords
This work can be used as a building block in other settings such as GPU, Map-Reduce, Spark or any other. Also, DDPML can be deployed on other distributed systems such as P2P…
Abstract
Purpose
This work can be used as a building block in other settings such as GPU, Map-Reduce, Spark or any other. Also, DDPML can be deployed on other distributed systems such as P2P networks, clusters, clouds computing or other technologies.
Design/methodology/approach
In the age of Big Data, all companies want to benefit from large amounts of data. These data can help them understand their internal and external environment and anticipate associated phenomena, as the data turn into knowledge that can be used for prediction later. Thus, this knowledge becomes a great asset in companies' hands. This is precisely the objective of data mining. But with the production of a large amount of data and knowledge at a faster pace, the authors are now talking about Big Data mining. For this reason, the authors’ proposed works mainly aim at solving the problem of volume, veracity, validity and velocity when classifying Big Data using distributed and parallel processing techniques. So, the problem that the authors are raising in this work is how the authors can make machine learning algorithms work in a distributed and parallel way at the same time without losing the accuracy of classification results. To solve this problem, the authors propose a system called Dynamic Distributed and Parallel Machine Learning (DDPML) algorithms. To build it, the authors divided their work into two parts. In the first, the authors propose a distributed architecture that is controlled by Map-Reduce algorithm which in turn depends on random sampling technique. So, the distributed architecture that the authors designed is specially directed to handle big data processing that operates in a coherent and efficient manner with the sampling strategy proposed in this work. This architecture also helps the authors to actually verify the classification results obtained using the representative learning base (RLB). In the second part, the authors have extracted the representative learning base by sampling at two levels using the stratified random sampling method. This sampling method is also applied to extract the shared learning base (SLB) and the partial learning base for the first level (PLBL1) and the partial learning base for the second level (PLBL2). The experimental results show the efficiency of our solution that the authors provided without significant loss of the classification results. Thus, in practical terms, the system DDPML is generally dedicated to big data mining processing, and works effectively in distributed systems with a simple structure, such as client-server networks.
Findings
The authors got very satisfactory classification results.
Originality/value
DDPML system is specially designed to smoothly handle big data mining classification.
Details
Keywords
Pravin Kumar and Rajesh K. Singh
The purpose of this paper is to provide an insight into the use of an integrated approach of fuzzy analytical hierarchy process (fuzzy AHP) and TOPSIS in evaluating the…
Abstract
Purpose
The purpose of this paper is to provide an insight into the use of an integrated approach of fuzzy analytical hierarchy process (fuzzy AHP) and TOPSIS in evaluating the performance of global third party logistics service providers for effective supply chain management.
Design/methodology/approach
In this study, the integration of fuzzy AHP with TOPSIS is proposed in determining the relative importance (weight) of criteria and then ranking of 3PLs.
Findings
Findings show that the logistics cost and service quality are two most important criteria for performance rating of 3PLs. Deciding the relative importance of various criteria for 3PLs evaluation is a complex task. The superiority of one criterion over the other varies from person to person and firm to firm. Therefore, to capture the variability in decision fuzzy extended AHP is very useful tool. Finally, the preference raking of alternatives are found using TOPSIS.
Research limitations/implications
Fuzzy AHP is a complex methodology and requires more numerical calculations than the traditional AHP and hence it increases the effort. But in this paper single stage fuzzy AHP is used to simplify the process. Fuzzy AHP is integrated with TOPSIS for preference ranking of 3PL, which provides a good methodology to rank 3PLs.
Originality/value
There is a lack of research in the literature to deal directly with the uncertainty of human decisions in evaluating the relative importance of multiple criteria. Therefore, fuzzy AHP is an appropriate methodology to find the relative importance of the criteria to rank the 3PLs using TOPSIS.