A LAGRANGIAN PARTICLE MODEL WITH CHEMICAL REACTIONS: APPLICATION IN REAL ATMOSPHERE

In this work a lagrangian particle model able to account for simple chemical reactions between NO and O3 (Alessandrini et al., 2007) has been improved in order to consider the photolysis of NO2. A system of chemical equations is numerically solved on an eulerian grid, while the particles trajectories are moved in a lagrangian frame. The NOx emissions of a power plant in real atmosphere, situated in a complex topography environment, have been considered as a test case. The meteorological model RAMS has been applied to build the wind field together with the interface code MIRS to compute turbulence parameters, requested for the dispersion simulations. The plume transitions over an air quality station, allowing for a comparison between the measured and computed concentrations of all the reaction’s compounds (NO, NO2 and O3), have been simulated by the lagrangian particle model. The simulated episodes refer to the diurnal time, when the ultraviolet radiation activates the NO2 photolysis making necessary the model complete set of chemical equations. In order to reduce computational cost and improve the accuracy of the background O3 concentration representation, the concept of concentration deficit carried by the particles is proposed and tested. This new method does not need to release a big amount of particles filling the whole domain, but only the inside plume particles should be accounted for. Comparisons between NO/NO2’s concentrations ratio are presented in term of scatter plots and statistical indexes analysis. The satisfactory results suggest that the model can be used in practical applications in real atmosphere also for regulatory purposes when the NO2 concentration limits are imposed by the legislation

Experimental analysis and dynamic simulation of solar cooling systems

2013/2014Il continuo aumento della richiesta di energia elettrica e la conseguente crescita dei valori di anidride carbonica nell'atmosfera terrestre crea sempre più la necessità di attuare modifiche sostanziali non solo nei metodi di produzione dei settori energetico e industriale, ma anche nella vita di ogni abitante del pianeta. Questa tesi analizza la possibilità di utilizzare l'energia solare per la produzione di acqua fredda grazie alla contemporaneità tra la disponibilità di energia rinnovabile e la richiesta di raffrescamento durante il periodo estivo. Due diversi impianti sperimentali, dotati di collettori solari a tubi evacuati commerciali e chiller ad adsoprbimento di piccole dimensioni (20 kW), sono stati monitorati ed i primi risultati sperimentali sono presentati in questo studio. Per studiare soluzioni diverse e trovare un design ottimale, un modello di simulazione dinamica è stato creato e testato utilizzando il software commerciale TRNSYS 17.XXVII Ciclo198

Improving the Analog Ensemble Wind Speed Forecasts for Rare Events

Abstract An analog-based ensemble technique, the analog ensemble (AnEn), has been applied successfully to generate probabilistic predictions of meteorological variables, wind and solar power, energy demand, and the optimal bidding in the day-ahead energy market. The AnEn method uses a historical time series of past forecasts from a meteorological model or other prediction systems and observations of the quantity to be predicted. For each forecast lead time, the ensemble set of predictions is a set of observations from the past. These observations are those concurrent with the past forecasts at the same lead time, chosen across the past runs most similar to the current forecast. Recent applications have demonstrated that the AnEn introduces a conditional negative bias when predicting events in the right tail of the forecast distribution of wind speed, particularly when the training dataset is short. This underestimation increases when the predicted event occurs less frequently in the available historical data. A new bias correction for the AnEn using wind observations from more than 500 U.S. stations is tested to reduce the AnEn's underestimation of rare events. It is shown that the conditional negative bias introduced by the AnEn in its standard application is significantly reduced by our novel approach. Also, the overall probabilistic AnEn performances improve when predicting wind speed higher than 10 m s−1 as demonstrated by lower values of the continuous ranked probability score. These improvements can be attributed to an increased reliability achieved by introducing the proposed bias correction algorithm

The “Weather Intelligence for Renewable Energies” Benchmarking Exercise on Short-Term Forecasting of Wind and Solar Power Generation.

International audienceA benchmarking exercise was organized within the framework of the European Action Weather Intelligence for Renewable Energies (" WIRE ") with the purpose of evaluating the performance of state of the art models for short-term renewable energy forecasting. The exercise consisted in forecasting the power output of two wind farms and two photovoltaic power plants, in order to compare the merits of forecasts based on different modeling approaches and input data. It was thus possible to obtain a better knowledge of the state of the art in both wind and solar power forecasting, with an overview and comparison of the principal and the novel approaches that are used today in the field, and to assess the evolution of forecast performance with respect to previous benchmarking exercises. The outcome of this exercise consisted then in proposing new challenges in the renewable power forecasting field and identifying the main areas for improving accuracy in the future

Modeling and Performance Analysis of an Integrated System: Variable Speed Operated Internal Combustion Engine Combined Heat and Power Unit\u2013Photovoltaic Array

The paper presents the model of a combined heat and power (CHP) unit, based on a variable speed internal combustion engine (ICE) interfaced with a photovoltaic (PV) system. This model is validated by means of experimental data obtained on an 85 kWe CHP unit fueled with natural gas and a PV system with a rated power of 17.9 kW. Starting from daily load profiles, the model is applied to investigate the primary energy saving (PES) of the integrated CHP\ufePV system in several operating conditions and for different sizes of PV array. The results demonstrate the dependence of the CHP performance on the operating mode and a limited convenience of the variable speed strategy. The integrated system operation leads to performance improvements, which depend on the size of the PV component

EU-PEMS PM Evaluation Program - First Report

The European legislation has adopted the Portable Emissions Measurement Systems (PEMS) as a tool to check the conformity of heavy-duty engines during their real operation. The current developments foresee the verification of gaseous emissions. The measurement and the control of in-service Particulate Mass (PM) emissions using on-board equipment has been delayed, as the technological status of the portable PM instrumentation had been judged insufficient. The European PEMS PM project was launched in 2007. Its main objective was to assess the technological status of the PEMS PM equipment. Initially, the main requirements set for the candidate instruments were: - to measure the PM mass, possibly according to existing standards; - to be designed for on-board testing regarding handling, test durations and power consumption; - to be advanced prototypes or commercially available equipment. An additional but important requirement was introduced: to be able to evaluate the in-service emissions (which is done in the United States through the Not To Exceed (NTE) approach), the European legislation has adopted a moving averaging window method. For such calculations, the accumulated PM mass had to be measured or estimated at any time during a test. The strategy used to evaluate the candidate instruments was simple and empirical. Using different engines, test cycles and fuels, the candidates were required to provide the best possible correlation with the reference laboratory systems. This ¿laboratory to portable¿ comparison was carried out for to the total PM mass measurements. The real-time PM results have been cross-correlated. In parallel to the program, some Particle Number (PN) measurements have been performed using equipment and test procedures in line with the European standards developed to test light-duty vehicles. This abstract provides the main findings of this project regarding PM, as presented and discussed in the final report of the European PEMS PM program. Furthermore, it gives the engine PN emissions and provides a first clue regarding the feasibility of PN for in-service testing. Different PM PEMS were evaluated in the lab with 3 heavy-duty engines which cover a wide range of emissions. The PM differences were in general 15% lower (SPC, OBS, micro-PSS) than the PM measured with a full dilution tunnel. Higher differences (35%) were found for MSS which measures soot. For the DPF engine the differences were >50% due to the volatile artifact on the filter. The PN differences between CVS and SPC were for all engines (and emission levels) within 15%. In addition to the PN method (non-volatiles measured with a CPC), MSS and DC were found to be sensitive enough at the low emission levels (post DPF). ETaPS and DMM (with dilution) were not sensitive enough for DPF engine. The conclusion of this work is that mass (on a filter) is not sensitive enough for low emission engines and the number method should be preferred. If PEMSs continue to use the filter method, then the real time instrument they use can affect the calculation factor as each instrument measures different particle property (number, surface, mass). Nevertheless, all these parameters do not affect the result enough to exceed the 10 mg/kWh limit of the future European HD regulation. They should be however seriously taken into account for lower emission levels.JRC.DDG.H.4-Transport and air qualit

An Automatic Framework for the Non-rigid Alignment of Electroanatomical Maps and Preoperative Anatomical Scans in Atrial Fibrillation

In atrial fibrillation, electro-anatomical maps (EAM) are used for ablation guidance. Yet, the anatomy reconstructed by the navigation system is known to be poorly accurate. This makes catheter navigation challenging and, as such, might affects ablation’s outcome. To ease navigation, existing systems allow co-registering EAMs with pre-operative MR scans by rigidly matching a set of manual landmarks. Nevertheless, the deformation between the two datasets is highly non-rigid. The aim of this work was therefore to develop a framework for the non-rigid alignment of EAMs and anatomical scans to improve ablation guidance

Preliminary Computational Framework to Map MRI-Derived Markers to predict Response to Cardiac Resynchronization Therapy

Prediction of the response to cardiac resynchronization therapy (CRT) is still uncertain. On our previous CRT clinical research, we have found that a decrease in the ratio between the two principal axes of the 3D trajectory of the electrode at the pacing site (S1/S2) recorded before and after pacing could define a marker between responders and non-responders to CRT. The aim of this work is to design a framework to map the S1/S2 marker on the 3D ventricular anatomy as a preliminary test to verify if the concept of the S1/S2 may predict the response to CRT in a pre-implant scenario. Based on MR images of a CRT candidate, the 3D mesh of the left ventricle geometry is constructed. Using image registration we are able to track the deformation of the mesh throughout the cardiac cycle and to compute the trajectory of each point of the mesh. Then the S1/S2 is calculated for every trajectory and mapped on a 3D geometry representation. We have applied this framework to one CRT patient, highlighting that in the area in which the electrode was placed the S1/S2 was low. This value suggests a poor possibility of a pacing-induced decrease for the S1/S2 ratio after implant. Consistently the patient was classified as non-responder at the clinical follow-up. Ongoing work focuses on the clinical validation of S1/S2 as a tool for the prediction of CRT response and the acquisition of MR data of potential candidates to CRT for the assessment of the presented framework