The Experts below are selected from a list of 293826 Experts worldwide ranked by ideXlab platform
Shengjun Zhang - One of the best experts on this subject based on the ideXlab platform.
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selection of working fluids for a novel low temperature geothermally Powered orc based cogeneRation system
Energy Conversion and Management, 2011Co-Authors: Huaixin Wang, Shengjun ZhangAbstract:A novel cogeneRation system driven by low-temperature geothermal sources was investigated in this study. This system consists of a low-temperature geothermally-Powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger and a commercial R134a-based heat pump subsystem. The main purpose is to identify appropriate fluids which may yield high PPR (the Ratio of Power produced by the Power geneRation subsystem to Power consumed by the heat pump subsystem) value and QQR (the Ratio of heat supplied to the user to heat produced by the geothermal source) value. Performances of the novel cogeneRation system under disturbance conditions have also been studied. Results indicate that fluids group presenting higher normal boiling point values shows averagely 7.7% higher PPR values and R236ea and R245ca outstand among the group. ΔTP (pinch temperature difference in heat exchangers) and ηt (turbine efficiency) values play more important roles on the variation of PPR values. QQR values change slightly with various ΔTP, ηt and ηrp (refrigerant pump efficiency) values while the variation range is larger under various geothermal source and heating supply parameters. Smaller ΔTP value, higher ηt value, higher geothermal source parameters and lower heating supply parameters lead to higher PPR values but lower QQR values.
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Working fluids of a low-temperature geothermally-Powered Rankine cycle for combined Power and heat geneRation system
Science China Technological Sciences, 2010Co-Authors: Tao Guo, Huaixin Wang, Shengjun ZhangAbstract:A novel combined Power and heat geneRation system was investigated in this study. This system consists of a low-temperature geothermally-Powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger and a commercial R134a-based heat pump subsystem. The advantages of the novel combined Power and heat geneRation system are free of using additional cooling water circling system for the Power geneRation subsystem as well as maximizing the use of thermal energy in the low-temperature geothermal source. The main purpose is to identify suitable working fluids (wet, isentropic and dry fluids) which may yield high PPR (the Ratio of Power produced by the Power geneRation subsystem to Power consumed by the heat pump subsystem) value and QQR (the Ratio of heat supplied to the user to heat produced by the geothermal source) value. Parameters under investigation were evaporating temperature, PPR value and QQR value. Results indicate that there exits an optimum evaporating temperature to maximize the PPR value and minimize the QQR value at the same time for individual fluid. And dry fluids show higher PPR values but lower QQR values. NH3 and R152a outstand among wet fluids. R134a outstands among isentropic fluids. R236ea, R245ca, R245fa, R600 and R600a outstand among dry fluids. R236ea shows the highest PPR value among the recommended fluids.
Huaixin Wang - One of the best experts on this subject based on the ideXlab platform.
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selection of working fluids for a novel low temperature geothermally Powered orc based cogeneRation system
Energy Conversion and Management, 2011Co-Authors: Huaixin Wang, Shengjun ZhangAbstract:A novel cogeneRation system driven by low-temperature geothermal sources was investigated in this study. This system consists of a low-temperature geothermally-Powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger and a commercial R134a-based heat pump subsystem. The main purpose is to identify appropriate fluids which may yield high PPR (the Ratio of Power produced by the Power geneRation subsystem to Power consumed by the heat pump subsystem) value and QQR (the Ratio of heat supplied to the user to heat produced by the geothermal source) value. Performances of the novel cogeneRation system under disturbance conditions have also been studied. Results indicate that fluids group presenting higher normal boiling point values shows averagely 7.7% higher PPR values and R236ea and R245ca outstand among the group. ΔTP (pinch temperature difference in heat exchangers) and ηt (turbine efficiency) values play more important roles on the variation of PPR values. QQR values change slightly with various ΔTP, ηt and ηrp (refrigerant pump efficiency) values while the variation range is larger under various geothermal source and heating supply parameters. Smaller ΔTP value, higher ηt value, higher geothermal source parameters and lower heating supply parameters lead to higher PPR values but lower QQR values.
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Working fluids of a low-temperature geothermally-Powered Rankine cycle for combined Power and heat geneRation system
Science China Technological Sciences, 2010Co-Authors: Tao Guo, Huaixin Wang, Shengjun ZhangAbstract:A novel combined Power and heat geneRation system was investigated in this study. This system consists of a low-temperature geothermally-Powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger and a commercial R134a-based heat pump subsystem. The advantages of the novel combined Power and heat geneRation system are free of using additional cooling water circling system for the Power geneRation subsystem as well as maximizing the use of thermal energy in the low-temperature geothermal source. The main purpose is to identify suitable working fluids (wet, isentropic and dry fluids) which may yield high PPR (the Ratio of Power produced by the Power geneRation subsystem to Power consumed by the heat pump subsystem) value and QQR (the Ratio of heat supplied to the user to heat produced by the geothermal source) value. Parameters under investigation were evaporating temperature, PPR value and QQR value. Results indicate that there exits an optimum evaporating temperature to maximize the PPR value and minimize the QQR value at the same time for individual fluid. And dry fluids show higher PPR values but lower QQR values. NH3 and R152a outstand among wet fluids. R134a outstands among isentropic fluids. R236ea, R245ca, R245fa, R600 and R600a outstand among dry fluids. R236ea shows the highest PPR value among the recommended fluids.
Ivan Stojmenovic - One of the best experts on this subject based on the ideXlab platform.
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Towards a Hybrid Energy Efficient Multi-Tree-Based Optimized Routing Protocol for Wireless Networks
Sensors, 2013Co-Authors: Nathalie Mitton, Tahiry Razafindralambo, David Simplot-ryl, Ivan StojmenovicAbstract:This paper considers the problem of designing Power efficient routing with guaranteed delivery for sensor networks with unknown geographic locations. We propose HECTOR, a hybrid energy efficient tree-based optimized routing protocol, based on two sets of virtual coordinates. One set is based on rooted tree coordinates, and the other is based on hop distances toward several landmarks. In HECTOR, the node currently holding the packet forwards it to its neighbor that optimizes Ratio of Power cost over distance progress with landmark coordinates, among nodes that reduce landmark coordinates and do not increase distance in tree coordinates. If such a node does not exist, then forwarding is made to the neighbor that reduces tree-based distance only and optimizes Power cost over tree distance progress Ratio. We theoretically prove the packet delivery and propose an extension based on the use of multiple trees. Our simulations show the superiority of our algorithm over existing alternatives while guaranteeing delivery, and only up to 30% additional Power compared to centralized shortest weighted path algorithm.
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Hector is an Energy effiCient Tree-based Optimized Routing protocol for wireless networks
2008Co-Authors: Nathalie Mitton, Tahiry Razafindralambo, David Simplot-ryl, Ivan StojmenovicAbstract:This paper considers the problem of designing Power efficient routing with guaranteed delivery for sensor networks with known distances between neighbors but unknown geographic locations. We propose HECTOR, a hybrid energy efficient tree-based optimized routing protocol, based on two sets of virtual coordinates. One set is based on rooted tree coordinates, and the other is based on hop distances toward several landmarks. In our algorithm, the node currently holding the packet forwards it to its neighbor that optimizes Ratio of Power cost over distance progress with landmark coordinates, among nodes that reduce landmark coordinates and do not increase tree coordinates. If such a node does not exist then forwarding is made to the neighbor that reduces tree based distance and optimizes Power cost over tree distance progress Ratio. Our simulations show the superiority of our algorithm over existing alternatives while guaranteeing delivery, and only up to 30 \% additional Power compared to centralized shortest weighted path algorithm.
Gilles Flamant - One of the best experts on this subject based on the ideXlab platform.
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On-sun opeRation of a 150 kWth pilot solar receiver using dense particle suspension as heat transfer fluid
Solar Energy, 2016Co-Authors: Inmaculada Pérez López, Daniel Gauthier, Hadrien Benoit, Gilles FlamantAbstract:Previous studies proved the Dense Particle Suspension (DPS) - also called Upward Bubbling Fluidized Bed (UBFB) - could be used as Heat Transfer Fluid (HTF) in a single-tube solar receiver. This article describes the experiments conducted on a 16-tube, 150 kWth solar receiver using a dense gas-particle suspension (around 30% solid volume fraction) flowing upward as HTF. The receiver was part of a whole pilot setup that allowed the continuous closed-loop circulation of the SiC particles used as HTF. One hundred hours of on-sun tests were performed at the CNRS 1 MW solar furnace in Odeillo. The pilot was tested under various ranges of operating parameters: solid mass flow rate (660–1760 kg/h), input solar Power (60–142 kW), and particle temperature before entering the solar receiver (40–180 °C). Steady states were reached during the experiments, with continuous circulation and constant particle temperatures. For the hottest case, the mean particle temperature reached 430 °C in the collector fluidized bed, at the receiver outlet, and it went up to 700 °C at the outlet of the hottest tube, during steady opeRation. A temperature difference between tubes is observed that is mainly due to the incident solar flux distribution heterogeneity. The thermal efficiency of the receiver, defined as the Ratio of Power transmitted to the DPS in the form of heat over solar Power entering the receiver cavity, was calculated in the range 50–90% for all the experimental cases. The system transient responses to variations of the solar irradiation and of the solid mass flow rate are also reported.
Nathalie Mitton - One of the best experts on this subject based on the ideXlab platform.
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Towards a Hybrid Energy Efficient Multi-Tree-Based Optimized Routing Protocol for Wireless Networks
Sensors, 2013Co-Authors: Nathalie Mitton, Tahiry Razafindralambo, David Simplot-ryl, Ivan StojmenovicAbstract:This paper considers the problem of designing Power efficient routing with guaranteed delivery for sensor networks with unknown geographic locations. We propose HECTOR, a hybrid energy efficient tree-based optimized routing protocol, based on two sets of virtual coordinates. One set is based on rooted tree coordinates, and the other is based on hop distances toward several landmarks. In HECTOR, the node currently holding the packet forwards it to its neighbor that optimizes Ratio of Power cost over distance progress with landmark coordinates, among nodes that reduce landmark coordinates and do not increase distance in tree coordinates. If such a node does not exist, then forwarding is made to the neighbor that reduces tree-based distance only and optimizes Power cost over tree distance progress Ratio. We theoretically prove the packet delivery and propose an extension based on the use of multiple trees. Our simulations show the superiority of our algorithm over existing alternatives while guaranteeing delivery, and only up to 30% additional Power compared to centralized shortest weighted path algorithm.
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Hector is an Energy effiCient Tree-based Optimized Routing protocol for wireless networks
2008Co-Authors: Nathalie Mitton, Tahiry Razafindralambo, David Simplot-ryl, Ivan StojmenovicAbstract:This paper considers the problem of designing Power efficient routing with guaranteed delivery for sensor networks with known distances between neighbors but unknown geographic locations. We propose HECTOR, a hybrid energy efficient tree-based optimized routing protocol, based on two sets of virtual coordinates. One set is based on rooted tree coordinates, and the other is based on hop distances toward several landmarks. In our algorithm, the node currently holding the packet forwards it to its neighbor that optimizes Ratio of Power cost over distance progress with landmark coordinates, among nodes that reduce landmark coordinates and do not increase tree coordinates. If such a node does not exist then forwarding is made to the neighbor that reduces tree based distance and optimizes Power cost over tree distance progress Ratio. Our simulations show the superiority of our algorithm over existing alternatives while guaranteeing delivery, and only up to 30 \% additional Power compared to centralized shortest weighted path algorithm.
