The Experts below are selected from a list of 4212 Experts worldwide ranked by ideXlab platform
William Dhaeseleer - One of the best experts on this subject based on the ideXlab platform.
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influence of the Pinch Point temperature difference on the performance of the preheat parallel configuration for a low temperature geothermally fed chp
Energy Procedia, 2017Co-Authors: Sarah Van Erdeweghe, Ben Laenen, Johan Van Bael, William DhaeseleerAbstract:Abstract In this work, we investigate the performance of the so-called Preheat-parallel CHP configuration, for the connection to a thermal network (TN). A low-temperature geothermal source (130°C), and the connection to a 75°C/50°C and a 75°C/35°C thermal network are considered. For a pure parallel CHP configuration, the brine delivers heat to the ORC and the thermal network in parallel. However, after having delivered heat to the ORC, the brine in the ORC branch still contains some energy which is not used. The Preheat-parallel configuration utilizes this heat to preheat the TN water before it enters the parallel branch, where the TN water is heated to the required supply temperature. The Preheat-parallel configuration is especially favorable when connected to a thermal network with a low return temperature, a large temperature difference between supply and return temperatures—thereby exploiting the preheating-effect—and for high heat demands. In this paper, we focus on the effect of the Pinch-Point-temperature difference (∆T Pinch ) on the plant performance. ∆T Pinch is directly related with the size and cost of the heat exchangers and strongly influences the preheating-effect, which is the most characteristic feature of the Preheat-parallel configuration. First, we present the results of a detailed sensitivity analysis of ∆T Pinch . A higher ∆T Pinch results in a lower preheating-effect, a lower net power output and, correspondingly, lower plant efficiency. Furthermore, we compare the performance of the Preheat-parallel configuration with the convenient parallel and series CHP configurations. For all three configurations, the performance decreases with an increase of ∆T Pinch . For the considered thermal network requirements, the net power generation is the highest for the Preheat-parallel configuration. With respect to the parallel configuration, the gain in net power generation stays approximately constant (75°C/35°C TN) or decreases (75°C/50°C TN) with the imposed Pinch-Point-temperature difference. With respect to the series configuration, the gain in net power generation increases for a higher value of ∆T Pinch . This means that the impact of ∆T Pinch is the biggest for the series configuration, followed by the Preheat-parallel configuration, and that the impact on the performance of the parallel configuration is the smallest.
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optimum configuration of shell and tube heat exchangers for the use in low temperature organic rankine cycles
Energy Conversion and Management, 2014Co-Authors: Daniel Walraven, Ben Laenen, William DhaeseleerAbstract:Abstract In this paper, a first step towards a system optimization of organic Rankine cycles (ORCs) is taken by optimizing the cycle parameters together with the configuration of shell-and-tube heat exchangers. In this way every heat exchanger has the optimum allocation of heat-exchanger surface, pressure drop and Pinch-Point-temperature difference for the given boundary conditions. Different tube configurations are investigated in this paper. It is concluded that the 30°-tube configurations should be used for the single-phase heat exchangers and the 60°-tube configuration for the two-phase heat exchangers. The performance of subcritical cycles can be strongly improved by adding a second pressure level. Recuperated cycles are only useful when the temperature of the heat source after the ORC should be relatively high.
Ben Laenen - One of the best experts on this subject based on the ideXlab platform.
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influence of the Pinch Point temperature difference on the performance of the preheat parallel configuration for a low temperature geothermally fed chp
Energy Procedia, 2017Co-Authors: Sarah Van Erdeweghe, Ben Laenen, Johan Van Bael, William DhaeseleerAbstract:Abstract In this work, we investigate the performance of the so-called Preheat-parallel CHP configuration, for the connection to a thermal network (TN). A low-temperature geothermal source (130°C), and the connection to a 75°C/50°C and a 75°C/35°C thermal network are considered. For a pure parallel CHP configuration, the brine delivers heat to the ORC and the thermal network in parallel. However, after having delivered heat to the ORC, the brine in the ORC branch still contains some energy which is not used. The Preheat-parallel configuration utilizes this heat to preheat the TN water before it enters the parallel branch, where the TN water is heated to the required supply temperature. The Preheat-parallel configuration is especially favorable when connected to a thermal network with a low return temperature, a large temperature difference between supply and return temperatures—thereby exploiting the preheating-effect—and for high heat demands. In this paper, we focus on the effect of the Pinch-Point-temperature difference (∆T Pinch ) on the plant performance. ∆T Pinch is directly related with the size and cost of the heat exchangers and strongly influences the preheating-effect, which is the most characteristic feature of the Preheat-parallel configuration. First, we present the results of a detailed sensitivity analysis of ∆T Pinch . A higher ∆T Pinch results in a lower preheating-effect, a lower net power output and, correspondingly, lower plant efficiency. Furthermore, we compare the performance of the Preheat-parallel configuration with the convenient parallel and series CHP configurations. For all three configurations, the performance decreases with an increase of ∆T Pinch . For the considered thermal network requirements, the net power generation is the highest for the Preheat-parallel configuration. With respect to the parallel configuration, the gain in net power generation stays approximately constant (75°C/35°C TN) or decreases (75°C/50°C TN) with the imposed Pinch-Point-temperature difference. With respect to the series configuration, the gain in net power generation increases for a higher value of ∆T Pinch . This means that the impact of ∆T Pinch is the biggest for the series configuration, followed by the Preheat-parallel configuration, and that the impact on the performance of the parallel configuration is the smallest.
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optimum configuration of shell and tube heat exchangers for the use in low temperature organic rankine cycles
Energy Conversion and Management, 2014Co-Authors: Daniel Walraven, Ben Laenen, William DhaeseleerAbstract:Abstract In this paper, a first step towards a system optimization of organic Rankine cycles (ORCs) is taken by optimizing the cycle parameters together with the configuration of shell-and-tube heat exchangers. In this way every heat exchanger has the optimum allocation of heat-exchanger surface, pressure drop and Pinch-Point-temperature difference for the given boundary conditions. Different tube configurations are investigated in this paper. It is concluded that the 30°-tube configurations should be used for the single-phase heat exchangers and the 60°-tube configuration for the two-phase heat exchangers. The performance of subcritical cycles can be strongly improved by adding a second pressure level. Recuperated cycles are only useful when the temperature of the heat source after the ORC should be relatively high.
Yuanyuan Duan - One of the best experts on this subject based on the ideXlab platform.
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effects of evaporator Pinch Point temperature difference on thermo economic performance of geothermal organic rankine cycle systems
Geothermics, 2018Co-Authors: Jie Sun, Qiang Liu, Yuanyuan DuanAbstract:Abstract Organic Rankine cycle (ORC) systems are being used to convert medium-low temperature geothermal energy into electricity. However, the ORC system efficiencies need to be increased and the investment costs need to be reduced to further promote this technology. The evaporator Pinch Point temperature difference (PPTD) is a key parameter affecting the thermodynamic and economic performance. A lower evaporator PPTD leads to higher turbine power output; however, this also increases the heat transfer area and the investment cost. Therefore, this work optimizes the evaporation temperatures to maximize the net power outputs for evaporator PPTDs of 4–15 °C and brine inlet temperatures of 100–150 °C. The heat transfer area per unit power output, the levelized cost of electricity (LCOE) and the dynamic payback period (PBP) at the optimal conditions are also analyzed. ORCs produce 1.7–2.6% more net power with every 1 °C decrease of the evaporator PPTD for brine inlet temperatures higher than 130 °C. The total area per unit power output first decreases to a minimum at an evaporator PPTD of about 7 °C and then increases slightly with increasing evaporator PPTD. The LCOE and the dynamic PBP of a basic ORC reach a minimum at an evaporator PPTD of about 7 °C with the minimum at 5–6 °C for drilling costs higher than 500 $/m.
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effects of evaporator Pinch Point temperature difference on thermo economic performance of geothermal organic rankine cycle systems
Geothermics, 2018Co-Authors: Yuanyuan DuanAbstract:Abstract Organic Rankine cycle (ORC) systems are being used to convert medium-low temperature geothermal energy into electricity. However, the ORC system efficiencies need to be increased and the investment costs need to be reduced to further promote this technology. The evaporator Pinch Point temperature difference (PPTD) is a key parameter affecting the thermodynamic and economic performance. A lower evaporator PPTD leads to higher turbine power output; however, this also increases the heat transfer area and the investment cost. Therefore, this work optimizes the evaporation temperatures to maximize the net power outputs for evaporator PPTDs of 4–15 °C and brine inlet temperatures of 100–150 °C. The heat transfer area per unit power output, the levelized cost of electricity (LCOE) and the dynamic payback period (PBP) at the optimal conditions are also analyzed. ORCs produce 1.7–2.6% more net power with every 1 °C decrease of the evaporator PPTD for brine inlet temperatures higher than 130 °C. The total area per unit power output first decreases to a minimum at an evaporator PPTD of about 7 °C and then increases slightly with increasing evaporator PPTD. The LCOE and the dynamic PBP of a basic ORC reach a minimum at an evaporator PPTD of about 7 °C with the minimum at 5–6 °C for drilling costs higher than 500 $/m.
Joh H Lienhard - One of the best experts on this subject based on the ideXlab platform.
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performance limits of zero and single extraction humidification dehumidification desalination systems
Applied Energy, 2013Co-Authors: Rona K Mcgove, Gregory P Thiel, Prakash G Naraya, Syed M Zubai, Joh H LienhardAbstract:Given simultaneous heat and mass transfer and a multiplicity of possible temperature and flow configurations, the optimization of humidification-dehumidification desalination systems is complex. In literature, this optimization has been tackled by considering moist air to follow the saturation curve in the humidifier and dehumidifier of a closed air water heated cycle. Under similar conditions and the same Pinch Point temperature differences, energy recovery was shown to improve with an increasing number of stages. In the present work, the limits upon the energy recovery and the water recovery (product water per unit of feed) of closed air water heated cycles are investigated. This is done by considering heat and mass exchangers to be sufficiently large to provide zero Pinch Point temperature and concentration differences with in the humidifier and dehumidifier. For cycles operating with a feed temperature of 25°C and a top air temperature of 70°C, GOR is limited to approximately 3.5 without extractions (i.e. single stage system) and 14 with a single extraction (i.e. dual stage system) while RR is limited to approximately 7% without extractions and 11% with a single extraction. GOR increases and RR decreases as the temperature range of the cycle decreases, i.e. as the feed temperature increases or the top air temperature decreases. A single extraction is shown to be useful only when heat and mass exchangers are large in size. In addition, the effects of salinity and the validity of ideal gas assumptions upon the modeling of HDH systems are discussed.
Ibrahim Dincer - One of the best experts on this subject based on the ideXlab platform.
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Energetic and exergetic performance evaluations of a geothermal power plant based integrated system for hydrogen production
International Journal of Hydrogen Energy, 2018Co-Authors: Yunus Emre Yuksel, Murat Ozturk, Ibrahim DincerAbstract:In this paper, we propose an integrated system aiming for hydrogen production with by-products using geothermal power as a renewable energy source. In analyzing the system, an extensive thermodynamic model of the proposed system is developed and presented accordingly. In addition, the energetic and exergetic efficiencies and exergy destruction rates for the whole system and its parts are defined. Due to the significance of some parameters, the impacts of varying working conditions are also investigated. The results of the energetic and exergetic analyses of the integrated system show that the energy and exergy efficiencies are 39.46% and 44.27%, respectively. Furthermore, the system performance increases with the increasing geothermal source temperature and reference temperature while it decreases with the increasing Pinch Point temperature and turbine inlet pressure.
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thermodynamic analysis and assessment of a novel integrated geothermal energy based system for hydrogen production and storage
International Journal of Hydrogen Energy, 2017Co-Authors: Yunus Emre Yuksel, Murat Ozturk, Ibrahim DincerAbstract:Abstract In this paper, thermodynamic analysis and assessment of a novel geothermal energy based integrated system for power, hydrogen, oxygen, cooling, heat and hot water production are performed. This integrated process consists of (a) geothermal subsystem, (b) Kalina cycle, (c) single effect absorption cooling subsystem and (d) hydrogen generation and storage subsystems. The impacts of some design parameters, such as absorption chiller evaporator temperature, geothermal source temperature, turbine input pressure and Pinch Point temperature on the integrated system performance are investigated to achieve more efficient and more effective. Also, the impacts of reference temperature and geothermal water temperature on the integrated system performance are studied in detail. The energetic and exergetic efficiencies of the integrated system are then calculated as 42.59% and 48.24%, respectively.
