International Journal of Heat and Mass Transfer, 2005
Flatter velocity profiles and more uniform thermal environments are extremely desirous factors fo... more Flatter velocity profiles and more uniform thermal environments are extremely desirous factors for improved performance in flow reactors and heat exchangers. One means of achieving it in laminar flow systems is to use mixers and flow inverters. In the present study a new ...
The mixing efficiency in a curved tube is a complex function of the Reynolds number, Schmidt numb... more The mixing efficiency in a curved tube is a complex function of the Reynolds number, Schmidt number, curvature ratio and tube pitch, therefore, the relative effectiveness of a helical tube is quite complicated and challenging over a straight tube. A state of art review on mixing of ...
The potential industrial applications of curved tubes for single-and two-phase flow are reviewed ... more The potential industrial applications of curved tubes for single-and two-phase flow are reviewed within the context of physics of flow, trends in the development of technology, and its laboratory to industrial-scale commercialization. Comparison of the performance of curved tube ...
In the present work attempts were made to investigate the hydrodynamics and heat transfer charact... more In the present work attempts were made to investigate the hydrodynamics and heat transfer characteristics of tube-in-tube helical heat exchanger at the pilot plant scale. The experiments were carried out in counter current mode operation with hot fluid in the tube side and cold fluid in the ...
The present study deals with the numerical simulation of flow patterns and mixing behaviour in Ke... more The present study deals with the numerical simulation of flow patterns and mixing behaviour in Kenics static mixer over a wide range of Reynolds number. Three different sets of Kenics mixer (aspect ratio = 1.5) comprised of 3, 9 and 25 elements each have been characterized. ...
In the present work attempts are made to investigate the hydrodynamics and heat-transfer characte... more In the present work attempts are made to investigate the hydrodynamics and heat-transfer characteristics of a coiled flow inverter (CFI) as heat exchanger at the pilot plant scale. The experiments are carried out in counter-current mode operation with hot fluid in the tube side and cold fluid in the shell side. Experimental study is made over a range of Reynolds numbers from 1000 to 16,000 using water in the tube side of the heat exchanger. The shell side fluids used are either cooling water or ambient air. The coiled flow inverter is made up of coils and 90 • bends and inserted in a closed shell. The shell side is fitted with three types of baffles to provide high turbulence and avoid channeling in the shell side. The bulk mean temperatures at various downstream positions are reported for different flow rate on tube side, as well as the heat transfer efficiency of the heat exchanger is also reported. Pressure drop and overall heat-transfer coefficient is calculated at various tube and shell side process conditions. The outer and inner heat-transfer coefficients are determined using Wilson plot technique. The results show that at low Reynolds numbers, heat-transfer is 25% higher as compared to coiled tubes. At high Reynolds numbers, the configuration has less influence on heat transfer. New empirical correlations are developed for hydrodynamic and heat-transfer predictions in the coiled flow inverter. ᭧
Helically coiled tubes find applications in various industrial processes like solar collectors, c... more Helically coiled tubes find applications in various industrial processes like solar collectors, combustion systems, heat exchangers, and distillation processes because of their simple and effective means of enhancement in heat and mass transfer. Though extensive work is ...
The pervasiveness of wireless communication recently gave mobile ad hoc networks (MANET) a signif... more The pervasiveness of wireless communication recently gave mobile ad hoc networks (MANET) a significant researcher's attention, due to its innate capabilities of instant communication in many time and mission critical applications. However, its natural advantages of networking in civilian and military environments make them vulnerable to security threats. Support for an anonymity in MANET is an orthogonal to security critical challenge we faced in this paper. We propose a new anonymous authentication protocol for mobile ad hoc networks enhanced with a distributed reputation system. The main its objective is to provide mechanisms concealing a real identity of communicating nodes with an ability of resist to known attacks. The distributed reputation system is incorporated for a trust management and malicious behavior detection in the network. The end-to-end anonymous authentication is conducted in three-pass handshake based on an asymmetric and symmetric key cryptography. After successfully finished authentication phase secure and multiple anonymous data channels are established. The anonymity is guarantied by randomly chosen pseudonyms owned by a user. Nodes of the network are publicly identified and are independent of users' pseudonyms. In this paper we presented an example of the protocol implementation.
Security is an important issue for any type of networks, especially for wireless ad-hoc networks.... more Security is an important issue for any type of networks, especially for wireless ad-hoc networks. Kerberos tickets used in KAMAN authentication scheme can be captured over the network are prone to replay attacks. The research work described in this document demonstrates that the modification in KAMAN protocol can increase authorization. We are proposed that all of contents are encapsulated in an encrypted packet. So the replay attacks become impossible. Moreover, in the proposed scheme there is no burden on the server and the client to undertake the modified KAMAN process. We also simulate describe architecture and verified that propose methods can reduce the chances of reply attack in MANET using KAMAN as authentication protocol.
International Journal of Heat and Mass Transfer, 2005
Flatter velocity profiles and more uniform thermal environments are extremely desirous factors fo... more Flatter velocity profiles and more uniform thermal environments are extremely desirous factors for improved performance in flow reactors and heat exchangers. One means of achieving it in laminar flow systems is to use mixers and flow inverters. In the present study a new ...
The mixing efficiency in a curved tube is a complex function of the Reynolds number, Schmidt numb... more The mixing efficiency in a curved tube is a complex function of the Reynolds number, Schmidt number, curvature ratio and tube pitch, therefore, the relative effectiveness of a helical tube is quite complicated and challenging over a straight tube. A state of art review on mixing of ...
The potential industrial applications of curved tubes for single-and two-phase flow are reviewed ... more The potential industrial applications of curved tubes for single-and two-phase flow are reviewed within the context of physics of flow, trends in the development of technology, and its laboratory to industrial-scale commercialization. Comparison of the performance of curved tube ...
In the present work attempts were made to investigate the hydrodynamics and heat transfer charact... more In the present work attempts were made to investigate the hydrodynamics and heat transfer characteristics of tube-in-tube helical heat exchanger at the pilot plant scale. The experiments were carried out in counter current mode operation with hot fluid in the tube side and cold fluid in the ...
The present study deals with the numerical simulation of flow patterns and mixing behaviour in Ke... more The present study deals with the numerical simulation of flow patterns and mixing behaviour in Kenics static mixer over a wide range of Reynolds number. Three different sets of Kenics mixer (aspect ratio = 1.5) comprised of 3, 9 and 25 elements each have been characterized. ...
In the present work attempts are made to investigate the hydrodynamics and heat-transfer characte... more In the present work attempts are made to investigate the hydrodynamics and heat-transfer characteristics of a coiled flow inverter (CFI) as heat exchanger at the pilot plant scale. The experiments are carried out in counter-current mode operation with hot fluid in the tube side and cold fluid in the shell side. Experimental study is made over a range of Reynolds numbers from 1000 to 16,000 using water in the tube side of the heat exchanger. The shell side fluids used are either cooling water or ambient air. The coiled flow inverter is made up of coils and 90 • bends and inserted in a closed shell. The shell side is fitted with three types of baffles to provide high turbulence and avoid channeling in the shell side. The bulk mean temperatures at various downstream positions are reported for different flow rate on tube side, as well as the heat transfer efficiency of the heat exchanger is also reported. Pressure drop and overall heat-transfer coefficient is calculated at various tube and shell side process conditions. The outer and inner heat-transfer coefficients are determined using Wilson plot technique. The results show that at low Reynolds numbers, heat-transfer is 25% higher as compared to coiled tubes. At high Reynolds numbers, the configuration has less influence on heat transfer. New empirical correlations are developed for hydrodynamic and heat-transfer predictions in the coiled flow inverter. ᭧
Helically coiled tubes find applications in various industrial processes like solar collectors, c... more Helically coiled tubes find applications in various industrial processes like solar collectors, combustion systems, heat exchangers, and distillation processes because of their simple and effective means of enhancement in heat and mass transfer. Though extensive work is ...
The pervasiveness of wireless communication recently gave mobile ad hoc networks (MANET) a signif... more The pervasiveness of wireless communication recently gave mobile ad hoc networks (MANET) a significant researcher's attention, due to its innate capabilities of instant communication in many time and mission critical applications. However, its natural advantages of networking in civilian and military environments make them vulnerable to security threats. Support for an anonymity in MANET is an orthogonal to security critical challenge we faced in this paper. We propose a new anonymous authentication protocol for mobile ad hoc networks enhanced with a distributed reputation system. The main its objective is to provide mechanisms concealing a real identity of communicating nodes with an ability of resist to known attacks. The distributed reputation system is incorporated for a trust management and malicious behavior detection in the network. The end-to-end anonymous authentication is conducted in three-pass handshake based on an asymmetric and symmetric key cryptography. After successfully finished authentication phase secure and multiple anonymous data channels are established. The anonymity is guarantied by randomly chosen pseudonyms owned by a user. Nodes of the network are publicly identified and are independent of users' pseudonyms. In this paper we presented an example of the protocol implementation.
Security is an important issue for any type of networks, especially for wireless ad-hoc networks.... more Security is an important issue for any type of networks, especially for wireless ad-hoc networks. Kerberos tickets used in KAMAN authentication scheme can be captured over the network are prone to replay attacks. The research work described in this document demonstrates that the modification in KAMAN protocol can increase authorization. We are proposed that all of contents are encapsulated in an encrypted packet. So the replay attacks become impossible. Moreover, in the proposed scheme there is no burden on the server and the client to undertake the modified KAMAN process. We also simulate describe architecture and verified that propose methods can reduce the chances of reply attack in MANET using KAMAN as authentication protocol.
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