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Kai Sundmacher - One of the best experts on this subject based on the ideXlab platform.
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optimal configuration and Pressure levels of electrolyzer plants in context of power to gas applications
Applied Energy, 2016Co-Authors: Boris Bensmann, Richard Hankerauschenbach, Gert Mullersyring, Marco Henel, Kai SundmacherAbstract:Typical power-to-gas plants mainly consist of a water electrolyzer, a mechanical compressor, an active cooler and a dryer. The best sequence of the single components as well as the Pressure levels throughout the process are ambiguous. They depend on the hydrogen Delivery Pressure and the humidity requirements of the final product.
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optimal configuration and Pressure levels of electrolyzer plants in context of power to gas applications
Applied Energy, 2016Co-Authors: Boris Bensmann, Richard Hankerauschenbach, Gert Mullersyring, Marco Henel, Kai SundmacherAbstract:Abstract Typical power-to-gas plants mainly consist of a water electrolyzer, a mechanical compressor, an active cooler and a dryer. The best sequence of the single components as well as the Pressure levels throughout the process are ambiguous. They depend on the hydrogen Delivery Pressure and the humidity requirements of the final product. The present analysis is based on a uniform technology independent model framework of the single process units. It allows for the calculation of the overall energy demand, independent of the requirements on hydrogen Pressure and water content. In the present contribution two main superordinate configurations, which differ in the sequence of mechanical compressor and dryer, are compared and the best Pressure profile throughout the process is determined. The analysis exemplarily focuses on hydrogen Delivery Pressures between 1 and 100 bar and an aimed maximal water content of 5 μ mol / mol , as required e.g. for automotive applications. The results show that the energy demand for drying dominates the total energy balance at low Delivery Pressure. Higher electrolyzer Pressures increase the losses due to hydrogen crossover. A mechanical compression prior to drying can be used to reduce the overall energy demand of the process. The electrolyzer Pressure can be kept below 20 bar, which reduces hydrogen crossover and besides enables anyhow efficient drying at high Pressures.
Rajesh K. Ahluwalia - One of the best experts on this subject based on the ideXlab platform.
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dynamics of cryogenic hydrogen storage in insulated Pressure vessels for automotive applications
International Journal of Hydrogen Energy, 2008Co-Authors: Rajesh K. Ahluwalia, J K PengAbstract:Abstract A dynamic model is used to characterize cryogenic H 2 storage in an insulated Pressure vessel that can flexibly hold liquid H 2 and compressed H 2 at 350 bar. A double-flow refueling device is needed to ensure that the tank can be consistently refueled to its theoretical capacity regardless of the initial conditions. Liquid H 2 charged into the tank is stored as supercritical fluid if the initial tank temperature is >120 K and as a subcooled liquid if it is 2 is stored as a supercritical fluid, liquid H 2 will form as H 2 is withdrawn and will further transform to a two-phase mixture and ultimately to a superheated gas. The recoverable fraction of the total stored inventory depends on the minimum H 2 Delivery Pressure and the power rating of the heater. The dormancy of cryogenic H 2 is a function of the maximum allowable Pressure and the Pressure of stored H 2 ; the evaporative losses cannot deplete H 2 from the tank beyond 64% of the theoretical storage capacity.
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sodium alanate hydrogen storage system for automotive fuel cells
International Journal of Hydrogen Energy, 2007Co-Authors: Rajesh K. AhluwaliaAbstract:Abstract Suitability of Ti-catalyzed sodium alanate as a reversible hydrogen storage system for automotive polymer–electrolyte fuel cells has been assessed under the constraint that it must meet certain performance criteria with respect to the amount of recoverable H 2 needed for vehicle driving range, minimum full-flow of H 2 needed to satisfy vehicular power demands, maximum refueling time and minimum H 2 Delivery Pressure. It is assumed that the thermal energy for desorbing hydrogen is supplied by the fluid that cools the high-temperature membrane fuel cell stack operating at 120 ∘ C . It is found that a ten-fold enhancement in published desorption kinetics is needed to attain 90% reversible H 2 storage capacity while satisfying the minimum full-flow requirement of 0.02 g H 2 /kWe. The catalyzed medium needs a metal foam support to facilitate heat removal necessary for 0.5–1.5 kg/min H 2 refueling rate. The faster the refueling rate, the higher is the peak heat transfer rate and the lower is the amount of recoverable H 2 . For a system with 5.6 kg recoverable H 2 , the peak heat transfer rate during refueling can exceed 1 MW. The overall specific energy and energy density of the storage medium are functions of the packing density of the metal hydride powder. The minimum acceptable hydrogen Delivery Pressure from the storage device determines the hydrogen storage capacity but otherwise has small influence on sorption kinetics.
Giampaolo Manzolini - One of the best experts on this subject based on the ideXlab platform.
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Life Cycle Assessment and Economic Analysis of an Innovative Biogas Membrane Reformer for Hydrogen Production
Processes, 2019Co-Authors: Gioele Di Marcoberardino, Arnaud Dauriat, Marco Binotti, Xun Liao, Giampaolo ManzoliniAbstract:This work investigates the environmental and economic performances of a membrane reactor for hydrogen production from raw biogas. Potential benefits of the innovative technology are compared against reference hydrogen production processes based on steam (or autothermal) reforming, water gas shift reactors and a Pressure swing adsorption unit. Both biogas produced by landfill and anaerobic digestion are considered to evaluate the impact of biogas composition. Starting from the thermodynamic results, the environmental analysis is carried out using environmental Life cycle assessment (LCA). Results show that the adoption of the membrane reactor increases the system efficiency by more than 20 percentage points with respect to the reference cases. LCA analysis shows that the innovative BIONICO system performs better than reference systems when biogas becomes a limiting factor for hydrogen production to satisfy market demand, as a higher biogas conversion efficiency can potentially substitute more hydrogen produced by fossil fuels (natural gas). However, when biogas is not a limiting factor for hydrogen production, the innovative system can perform either similar or worse than reference systems, as in this case impacts are largely dominated by grid electric energy demand and component use rather than conversion efficiency. Focusing on the economic results, hydrogen production cost shows lower value with respect to the reference cases (4 €/kgH2 vs 4.2 €/kgH2) at the same hydrogen Delivery Pressure of 20 bar. Between landfill and anaerobic digestion cases, the latter has the lower costs as a consequence of the higher methane content.
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Potentiality of a biogas membrane reformer for decentralized hydrogen production
Chemical Engineering and Processing - Process Intensification, 2018Co-Authors: Gioele Di Marcoberardino, Stefano Foresti, Marco Binotti, Giampaolo ManzoliniAbstract:This paper investigates the potentiality of membrane reactor for green hydrogen production from raw biogas. The assessment is carried out both from thermodynamic and economic point of view to outline the advantages of the innovative technology with respect to the conventional one based on reforming, water gas shift and Pressure swing adsorption unit. Both biogas produced by landfill and anaerobic digestion are considered to evaluate the impact of biogas composition on system design. BIONICO system model is implemented in Aspen Plus and Aspen Custom Modeler to perform respectively the balance of plant with thermal integration and a detailed fluidized bed membrane reactor design. Two permeate side configurations, sweep gas and vacuum pump, were modelled and compared. The adoption of membrane reactor increases the system efficiency by more than 20% points with respect to reference cases. Focusing on the economic results, hydrogen production cost show lower value respect to the reference cases (4 €/kgH2vs 4.2 €/kgH2) at the same hydrogen Delivery Pressure of 20 bar. Between the landfill and anaerobic digestion cases, the latter has the lower costs as consequence of the higher methane content.
J K Peng - One of the best experts on this subject based on the ideXlab platform.
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dynamics of cryogenic hydrogen storage in insulated Pressure vessels for automotive applications
International Journal of Hydrogen Energy, 2008Co-Authors: Rajesh K. Ahluwalia, J K PengAbstract:Abstract A dynamic model is used to characterize cryogenic H 2 storage in an insulated Pressure vessel that can flexibly hold liquid H 2 and compressed H 2 at 350 bar. A double-flow refueling device is needed to ensure that the tank can be consistently refueled to its theoretical capacity regardless of the initial conditions. Liquid H 2 charged into the tank is stored as supercritical fluid if the initial tank temperature is >120 K and as a subcooled liquid if it is 2 is stored as a supercritical fluid, liquid H 2 will form as H 2 is withdrawn and will further transform to a two-phase mixture and ultimately to a superheated gas. The recoverable fraction of the total stored inventory depends on the minimum H 2 Delivery Pressure and the power rating of the heater. The dormancy of cryogenic H 2 is a function of the maximum allowable Pressure and the Pressure of stored H 2 ; the evaporative losses cannot deplete H 2 from the tank beyond 64% of the theoretical storage capacity.
Emma Frosina - One of the best experts on this subject based on the ideXlab platform.
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Effects of PCFV and Pre-Compression Groove on the Flow Ripple Reduction in Axial Piston Pumps
2018 Global Fluid Power Society PhD Symposium (GFPS), 2018Co-Authors: Emma Frosina, Gianluca Marinaro, Adolfo Senatore, Michele PavanettoAbstract:This paper represents the results obtained with a preliminary numerical methodology adopted to reduce noise in axial piston pumps. Starting from a preliminary design (further called “Valve plate #1”), two different valve plates have been proposed comparing their contribution to reduction of flow ripple. The pump is an open circuit axial piston pump, swash plate designed with nine-piston and a maximum displacement of 65.9 cm3/rev. A three-dimensional CFD model of the first pump design has been built up with the commercial code PumpLinx®, developed by Simerics Inc. The numerical model has been validated, considering the pump rotation, fluid characteristic and leakages. The pump has been tested by the pump manufacturer in all the working conditions. The first valve plate design (“Valve plate #1”) has been modified optimizing the pre-compression relief groove design (“Valve plate #2”) and including a pre-compression filter volume (PCFV, “Valve plate #3”) The Valve plate #2, including an optimized pre-compression groove, has been designed mainly to improve the volumetric efficiency and as well as to reduce the flow ripple. The second solution (“Valve plate #3 has been obtained on the basis of the Valve plate #2, including a PCFV to reduce the reverse flow back to the cylinder chamber. All the designs presented in this paper have been modelled for minimizing the peak-to-peak discharge flow ripple at the pump full displacements and for the rotational speed of 1500rpm Delivery Pressure. The best geometry has been found demonstrating that, with the introduction of the PCFV into axial piston pump, the reverse flow has been drastically reduced up to 40%. This research is result of a collaboration among the University of Naples “Federico II” and the pump manufacturers Duplomatic MS and Continental Hydraulics Inc.
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study of a high Pressure external gear pump with a computational fluid dynamic modeling approach
Energies, 2017Co-Authors: Emma Frosina, Adolfo Senatore, Manuel RigosiAbstract:A study on the internal fluid dynamic of a high-Pressure external gear pump is described in this paper. The pump has been analyzed with both numerical and experimental techniques. Starting from a geometry of the pump, a three-dimensional computational fluid dynamics (CFD) model has been built up using the commercial code PumpLinx®. All leakages have been taken into account in order to estimate the volumetric efficiency of the pump. Then the pump has been tested on a test bench of Casappa S.p.A. Model results like the volumetric efficiency, absorbed torque, and outlet Pressure ripple have been compared with the experimental data. The model has demonstrated the ability to predict with good accuracy the performance of the real pump. The CFD model has been also used to evaluate the effect on the pump performance of clearances in the meshing area. With the validated model the Pressure inside the chambers of both driving and driven gears have been studied underlining cavitation in meshing fluid volume of the pump. For this reason, the model has been implemented in order to predict the cavitation phenomena. The analysis has allowed the detection of cavitating areas, especially at high rotation speeds and Delivery Pressure. Isosurfaces of the fluid volume have been colored as a function of the total gas fraction to underline where the cavitation occurs.
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Gerotor pump cavitation monitoring and fault diagnosis using vibration analysis through the employment of auto-regressive-moving-average technique
Simulation Modelling Practice and Theory, 2017Co-Authors: Dario Buono, Daniela Siano, Emma Frosina, Adolfo SenatoreAbstract:Gerotor pumps, as well known, are widely used in lubrication circuits of internal combustion engines for their simplicity, high efficiency and low costs. In this paper an experimental characterization of a Gerotor pump is shown. The research is a collaboration between the Hydraulic Power Research Group (HPRG) of the University of Naples “Federico II” and the Istituto Motori of CNR. The aim of this research is to investigate the possibility of using simple data to acquire, as vibrational data, on the pump under investigation to detect possible cavitation problem by implementing a proper mathematical procedure to this aim. As been demonstrated that these pumps are particularly subject to cavitation. The gerotor pumps are much subject to cavitate than expected, especially under particular operating conditions of the engine. Cavitation is also correlate to vehicle dynamics particularly with the recent tendency to reduce the mass of oil in the sump. Therefore, the research to avoid cavitation is crucial nowadays. Consequently this study has been firstly performed with an experimentation on the pump by monitoring the delivered oil flow-rate and the adsorbed torque on the pump shaft. An accurate analysis of the Pressure oscillations in cavitation conditions, has been, also, conducted. Then, an accelerometer sensor has been properly located to study the cavitation with a fault diagnosis system based on vibration detection. The experimental tests have been performed on a test bench of the Hydraulic Laboratory of the University of Naples “Federico II” in Italy. The bench allows testing the pump working by varying the shaft speed, the oil temperature, the suction and the Delivery Pressure. The main measured parameters are shaft torque, oil flow rate, mean suction and Delivery Pressure and the instantaneous suction and Delivery Pressure. As expected, tests revealed the high influence of the suction Pressure on the delivered oil flow rate, while no significant influence has been noted on the adsorbed torque. Furthermore, the Pressure oscillations in the pump Delivery are highly influenced by the suction Pressure. A non intrusive accelerometer has been installed during the experimentation on the oil pump. Since the vibration due to cavitation is the main concern of this study, the accelerometer has been mounted at the suction port in the radial direction. More precisely, the paper presents a fault diagnosis system based on vibration detection. Firstly, a Fast Fourier Transform of the vibration signal has been computed. The investigation has been made with and without the presence of cavitation varying the pump rotation speeds. Limitations due to the detecting of the on line cavitation problems by monitoring the FFT vibration spectra have been overcame by implementing an alternative method based on stochastic approach. This diagnosis method of accelerometer time series analysis based on an Auto Regressive and Moving Average (ARMA) method has been used to determine the pump failure. The diagnosis results have demonstrated the ability of the proposed mathematical technique in the identification of cavitation phenomena proving that the proposed approach is a useful methodology to detect the presence of fault. The approach can predict, with good accuracy, pump failure in real time operation. In addition, a threshold vibration level in decibel scale is also fixed.