scholarly journals The climatic response of thermally integrated photovoltaic–electrolysis water splitting using Si and CIGS combined with acidic and alkaline electrolysis

2020 ◽  
Vol 4 (12) ◽  
pp. 6011-6022 ◽  
Author(s):  
İ. Bayrak Pehlivan ◽  
U. Malm ◽  
P. Neretnieks ◽  
A. Glüsen ◽  
M. Müller ◽  
...  
Keyword(s):  
Water Splitting ◽  
Real Data ◽  
Climatic Data ◽  
Hydrogen Yield ◽  
Data Modelling ◽  
Climatic Response ◽  
European Climate ◽  
Alkaline Electrolysis

Real data modelling of the hydrogen yield using different PV and electrolyzer combinations with hourly climatic data for mid-European climate.

What every mathematician should know about modelling crime

2010 ◽  
Vol 21 (4-5) ◽  
pp. 275-281 ◽  
Author(s):  
MARCUS FELSON
Keyword(s):  
Mathematical Models ◽  
Real Data ◽  
Future Research ◽  
Data Modelling

This paper by a criminologist explains why it makes more sense to model criminal acts than to model criminals, how many preconceptions about crime can mislead modellers and offers some simple crime modelling ideas. Many opportunities for simulation now exist, and new opportunities for real-data modelling are emerging. The author suggests mathematical models of crime, including offender foraging for crime targets, as a rich area for future research.

scholarly journals Ventilated Double Window for the Preheating of the Ventilation Air Comparison of Its Performance in a Northern and a Southern European Climate

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Jorge S. Carlos ◽  
Helena Corvacho
Keyword(s):  
Sensitivity Analysis ◽  
Solar Radiation ◽  
Indoor Air ◽  
Climatic Data ◽  
Relevant Factor ◽  
Outdoor Air ◽  
Cold Winter ◽  
Passive System ◽  
Reference Levels ◽  
European Climate

Keeping the indoor air quality within the reference levels requires that the polluted indoor air be replaced by fresh air coming from the outside. This paper presents a sensitivity analysis and a series of simulations where the performance of this passive system is studied. The influence of each relevant factor, like the wind, the solar radiation, and the outdoor air temperature, is assessed. Two different local sets of climatic data were chosen, a mild and a cold winter.

scholarly journals OPERATION ANALYSIS OF THE AIR-SOURCE HEAT PUMP USING TRNSYS SIMULATION TOOL

2021 ◽  
Vol 13 (0) ◽  
pp. 1-6
Author(s):  
Gabrielė Daugirdaitė ◽  
Giedrė Streckienė ◽  
Tomas Kropas
Keyword(s):  
Heat Pump ◽  
Real Data ◽  
Cold Season ◽  
Heat Pumps ◽  
Climatic Data ◽  
Pump Operation ◽  
Operation Analysis ◽  
Air Source Heat Pump ◽  
Heating Capacity ◽  
Heating Mode

In order to achieve ambitious goals for energy efficiency and requirements for near zero energy buildings, various technological solutions enabling the use of renewable energy are proposed and applied. One such rapidly spreading technology is heat pumps. However, the use of air-­to-­water heat pumps in countries where the cold season is cold and humid has unfavourable conditions for the operation of this equipment during the heating season. As a result, the performance efficiency of the equipment decreases. This article presents the simulation results of an air-­to-­water heat pump operation in Lithuania using the TRNSYS modelling tool; its nominal heating capacity is 6.55 kW. The model was calibrated using real data obtained at Vilnius Gediminas Technical University when measurements were performed under heat pump freezing conditions. The seasonal performance factor of the heat pump heating mode was determined during the calculation. Parametric analysis of the model was also performed, when sensitivity of the model to the initial climatic data was observed. Comparable results are obtained for Vilnius, Prague and London.

Tin as a Possible Candidate for Solar Thermochemical Redox Process for Hydrogen Production

2007 ◽  
Author(s):  
Irina Vishnevetsky ◽  
Michael Epstein
Keyword(s):  
Hydrogen Production ◽  
Water Splitting ◽  
Industrial Production ◽  
Reducing Agents ◽  
Redox Process ◽  
Hydrogen Yield ◽  
Promising Candidate ◽  
Experimental Conditions ◽  
Hydrolysis Process ◽  
Reactor Temperature

The feasibility to produce hydrogen in the Sn-H2O/SnO2-C thermochemical water splitting redox process depends mainly on the efficiency of the tin hydrolysis step which has not been studied adequately so far, whereas the carboreduction step was investigated because of the industrial production of tin from its mineral casseterite using charcoal or anthracite as reducing agents. The present work deals with the hydrolysis process of different kinds of tin powders at different experimental conditions at moderate temperature range of 180–620°C. In spite of the fact that the rate of hydrogen production is lower compared to other metals e.g. zinc, at the same reactor temperature, high conversion and hydrogen yield were obtained in a controllable reaction. Consequently, tin can be a promising candidate considering the advantage of significant lower temperatures required for the solar carboreduction of its oxide.

scholarly journals CFD Simulation of Hydrogen Generation and Methane Combustion Inside a Water Splitting Membrane Reactor

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7175
Author(s):  
Te Zhao ◽  
Chusheng Chen ◽  
Hong Ye
Keyword(s):  
Water Splitting ◽  
Flow Rate ◽  
Membrane Reactor ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Hydrogen Generation ◽  
Methane Combustion ◽  
Inlet Temperature ◽  
Hydrogen Yield ◽  
Gas Flow Rate

Hydrogen production from water splitting remains difficult due to the low equilibrium constant (e.g., Kp ≈ 2 × 10−8 at 900 °C). The coupling of methane combustion with water splitting in an oxygen transport membrane reactor can shift the water splitting equilibrium toward dissociation by instantaneously removing O2 from the product, enabling the continuous process of water splitting and continuous generation of hydrogen, and the heat required for water splitting can be largely compensated for by methane combustion. In this work, a CFD simulation model for the coupled membrane reactor was developed and validated. The effects of the sweep gas flow rate, methane content and inlet temperature on the reactor performance were investigated. It was found that coupling of methane combustion with water splitting could significantly improve the hydrogen generation capacity of the membrane reactor. Under certain conditions, the average hydrogen yield with methane combustion could increase threefold compared to methods that used no coupling of combustion. The methane conversion decreases while the hydrogen yield increases with the increase in sweep gas flow rate or methane content. Excessive methane is required to ensure the hydrogen yield of the reactor. Increasing the inlet temperature can increase the membrane temperature, methane conversion, oxygen permeation rate and hydrogen yield.

Analysis of Thermodynamics of Two-Step Solar Water Splitting

2008 ◽  
Author(s):  
Martin Roeb ◽  
Nils Gathmann ◽  
Martina Neises ◽  
Christian Sattler ◽  
Robert Pitz-Paal
Keyword(s):  
Iron Oxide ◽  
Oxygen Uptake ◽  
Water Splitting ◽  
Iron Oxides ◽  
Material Properties ◽  
Fine Tuning ◽  
Process Conditions ◽  
Hydrogen Yield ◽  
Solar Water Splitting ◽  
Production Of Hydrogen

A two-step thermo-chemical cycle for solar production of hydrogen from water has been developed and investigated. It is based on metal oxide redox pair systems, which can split water molecules by abstracting oxygen atoms and reversibly incorporating them into their lattice. After proof-of-principle, successful experimental demonstration of several cycles of alternating hydrogen and oxygen production, and elaboration of process strategies presented in previous contributions, the present work describes a thermodynamic study aiming at the fine tuning of the redox system, at the improvement of process conditions, and at the evaluation of the potential of the process. For the redox material the oxygen uptake capability is an essential characteristic, because it is directly connected to the amount of hydrogen which can be produced. In order to evaluate the maximum oxygen uptake potential of a coating material and to be able to find new redox materials theoretical considerations based on thermodynamic laws and properties are helpful and faster than actual tests. Through thermodynamic calculations it is possible to predict the theoretical maximum output of H2 from a specific redox-material under certain conditions. Calculations were focussed on the two mixed iron oxides nickel-iron oxide and zinc-iron oxide. In the simulation the amount of oxygen in the redox-material is calculated before and after the splitting step on the basis of laws of thermodynamics and available material properties for the mixed-iron oxides used. For the simulation the commercial Software FactSage and available databases for the necessary material properties were used. The analysis showed that a maximum hydrogen yield is achieved if the regeneration temperature is raised to the limits of the operation range, if the temperature for the water splitting is lowered below 800 °C and if the partial pressure of oxygen during regeneration is decreased to the lower limits of the operational range. The increased hydrogen yield at lower splitting temperature of about 800 °C could not be confirmed in experimental results, where a higher splitting temperature led to a higher hydrogen yield. As a consequence it can be stated that kinetics must play an important role especially in the splitting step.

Nanostructured cobalt phosphide-based films as bifunctional electrocatalysts for overall water splitting

RSC Advances ◽  
2015 ◽  
Vol 5 (128) ◽  
pp. 105814-105819 ◽  
Author(s):  
Julian A. Vigil ◽  
Timothy N. Lambert
Keyword(s):  
Water Splitting ◽  
Oxygen Evolution ◽  
Electrolysis Cell ◽  
Cobalt Phosphide ◽  
Overall Water Splitting ◽  
Bifunctional Electrocatalysts ◽  
Low Overpotential ◽  
Alkaline Electrolysis

Nanostructured cobalt phosphide-based films (Co-PP) were shown to be effective bifunctional electrocatalysts for the hydrogen and oxygen evolution reactions. A symmetrical alkaline electrolysis cell demonstrated low overpotential for water splitting.

scholarly journals Study of Activity and Super-Capacitance Exhibited by Bifunctional Raney 2.0 Catalyst for Alkaline Water-Splitting Electrolysis

Hydrogen ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 1-17
Author(s):  
William J. F. Gannon ◽  
Charles W. Dunnill
Keyword(s):  
Hydrogen Production ◽  
Water Splitting ◽  
High Performance ◽  
Large Scale ◽  
Low Cost ◽  
Electrochemical Techniques ◽  
Bifunctional Electrocatalyst ◽  
Energy Capture ◽  
A New Technique ◽  
Alkaline Electrolysis

Low-cost, high-performance coatings for hydrogen production via electrolytic water-splitting are of great importance for de-carbonising energy. In this study the Raney2.0 coating was analysed using various electrochemical techniques to assess its absolute performance, and it was confirmed to have an extremely low overpotential for hydrogen evolution of just 28 mV at 10 mA/cm2. It was also confirmed to be an acceptable catalyst for oxygen evolution, making it the highest performing simple bifunctional electrocatalyst known. The coating exhibits an extremely high capacitance of up to 1.7 F/cm2, as well as being able to store 0.61 J/cm2 in the form of temporary hydride deposits. A new technique is presented that performs a best-fit of a transient simulation of an equivalent circuit containing a constant phase element to cyclic voltammetry measurements. From this the roughness factor of the coating was calculated to be approximately 40,000, which is the highest figure ever reported for this type of material. The coating is therefore an extremely useful improved bifunctional coating for the continued roll-out of alkaline electrolysis for large-scale renewable energy capture via hydrogen production.

scholarly journals The Climatic Response of Tree Ring Width Components of Ash (Fraxinus excelsior L.) and Common Oak (Quercus robur L.) from Eastern Europe

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 600
Author(s):  
Cătălin-Constantin Roibu ◽  
Victor Sfeclă ◽  
Andrei Mursa ◽  
Monica Ionita ◽  
Viorica Nagavciuc ◽  
...  
Keyword(s):  
Eastern Europe ◽  
Tree Ring ◽  
Quercus Robur ◽  
Ring Width ◽  
Fraxinus Excelsior ◽  
Drought Indices ◽  
Climatic Data ◽  
Climatic Response ◽  
Republic Of Moldova ◽  
The Republic

This paper aims to develop the first differentiated (earlywood—EW, latewood—LW, and total ring width—RW) dendrochronological series for ash (Fraxinus excelsior L.) and oak (Quercus robur L.) trees from the Republic of Moldova, and to analyze their climatic response and their spatio-temporal stability. For this, 18 ash and 26 oak trees were cored from the Dobrușa protected area, Republic of Moldova, Eastern Europe, and new EW, LW, and RW chronologies were developed for ash and oak covering the last century. The obtained results showed that the RW and LW have a similar climatic response for both species, while EW is capturing interannual climate variations and has a different reaction. The analyses performed with monthly climatic data revealed a significant and negative correlation with the mean air temperature and a significant and positive correlation with precipitation and the Standardized Precipitation-Evapotranspiration Index (SPEI) for both ash and oak. The temperature during the vegetation period has a strong influence on all tree-ring components of ash, while for oak the strong correlation was found only for LW. The positive and significant correlation between LW and RW with precipitation for both species, suggests that ash and oak are sensitive to the hydrological component and the precipitation is the main tree growth-limiting factor. Despite the significant correlation with precipitation and temperature for the whole analyzed period, the 25-year moving correlation analyses show that they are not stable in time and can switch from positive to negative or vice versa, while the correlation with SPEI3 drought index, which is a integration of both climatic parameters, is stable in time. By employing the stability map analysis, we show that oak and ash tree ring components, from the eastern part of the Republic of Moldova, have a stable and significant correlation with SPEI3 and scPDSI drought indices from February (January) until September, over the eastern part of Europe.

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