Multi-criteria investigation of a pumped thermal electricity storage (PTES) system with thermal integration and sensible heat storage

In the present paper a multicriteria analysis of a Rankine Pumped Thermal Electricity Storage (PTES) system with low-grade thermal energy integration is performed. The system is composed by an ORC for the discharging phase and a high-temperature heat pump for the charging phase. As previously demonstrated, the low-grade thermal energy can be provided at the heat pump evaporator to boost the PTES performances. As it regards the multi-criteria analysis, a tradeoff is required when electric-to-electric energy ratio ηrt, total exergy exploitation efficiency ψut and energy density ρen, are maximized concurrently. By means of multi-objective optimization, theoretical performances of the system are derived in two different layouts, which are differentiated by the presence, or not, of internal regeneration in charge and discharge subsystems. Results showed that regeneration can be very effective, as it relaxes the tradeoff between the objectives, thus yielding better global performances. Pareto fronts are built and explored to characterize the PTES system. Configurations of interest are proposed, and PTES performances are compared with other storage technologies. Theoretical results showed that, by exploiting thermal energy at temperature lower than 80 °C, ηrt ≈ 0.55 and ρen ≈ 15 kWh/m3 can be concurrently achieved. This can be done at the cost of an inefficient exploitation of the thermal source, as ψut ≈ 0.05. If higher total exergy utilization efficiency is required, storage density can still be maintained high, but ηrt must drop down to 0.4

Rankine carnot batteries with the integration of thermal energy sources: A review

This paper provides an overview of a novel electric energy storage technology. The Thermally Integrated Pumped Thermal Electricity Storage (TI-PTES) stores electric energy as thermal exergy. Compared to standard PTES, TI-PTES takes advantage of both electric and low-temperature heat inputs. Therefore, TI-PTES is a hybrid technology between storage and electric production from low-temperature heat. TI-PTES belongs to a technology group informally referred to as Carnot Batteries (CBs). As the TI-PTES grows in popularity, several configurations have been proposed, with different claimed performances, but no standard has emerged to date. The study provides an overview of the component and operating fluid selection, and it describes the configurations proposed in the literature. Some issues regarding the performance, the ratio between thermal and electrical inputs, and the actual TI-PTES utilisation in realistic scenarios are discussed. As a result, some guidelines are defined. The configurations that utilise high-temperature thermal reservoirs are more extensively studied, due to their superior thermodynamic performance. However, low-temperature TI-PTES may achieve similar performance and have easier access to latent heat storage in the form of water ice. Finally, to achieve satisfactory performance, TI-PTES must absorb a thermal input several times larger than the electric one. This limits TI-PTES to small-scale applications

Influence of emitter-receiver number on measurement accuracy in acoustic pyrometry

Acoustic pyrometry is an interesting technique that may find several useful applications in turbomachinery. As the speed of sound is directly related a medium temperature, this measurement technique estimates the temperature of a gas by considering the time of flight of an acoustic wave moving through it. If only an acoustic emitter-receiver couple is used, only the average temperature along the acoustic path can be determined. If multiple emitter-receiver couples laying on the same plane are used, a reconstruction of the temperature map in the section is possible. This estimation is performed by considering that multiple acoustic paths travel across the same sub-portions of the section and, therefore, the temperature of each sub-portion affects the time of flight along several sound paths. Many parameters affect the accuracy of the measurement, and they are related to the physic of the phenomena involved in the measurement, the accuracy of the instrumentation used, the interaction between the acoustic wave and the flow velocity and the hardware set-up. In this study, the impact of some set-up parameters on the accuracy of the measurement was investigated and, in particular, the number of sound emitter-receiver couples and the number of investigation sub-portions in which the section is divided. A reference temperature map has been considered as a benchmark. This study, which is a preliminary investigation on this technique, was useful to assess the capability of this methodology to correctly describe a temperature distribution in an ideal condition. Therefore, it represents a first step in the set-up of an experimental investigation with an acoustic pyrometer.

Urban surface temperature time series estimation at the local scale by spatial-spectral unmixing of satellite observations

The study of urban climate requires frequent and accurate monitoring of land surface temperature (LST), at the local scale. Since currently, no space-borne sensor provides frequent thermal infrared imagery at high spatial resolution, the scientific community has focused on synergistic methods for retrieving LST that can be suitable for urban studies. Synergistic methods that combine the spatial structure of visible and near-infrared observations with the more frequent, but low-resolution surface temperature patterns derived by thermal infrared imagery provide excellent means for obtaining frequent LST estimates at the local scale in cities. In this study, a new approach based on spatial-spectral unmixing techniques was developed for improving the spatial resolution of thermal infrared observations and the subsequent LST estimation. The method was applied to an urban area in Crete, Greece, for the time period of one year. The results were evaluated against independent high-resolution LST datasets and found to be very promising, with RMSE less than 2 K in all cases. The developed approach has therefore a high potential to be operationally used in the near future, exploiting the Copernicus Sentinel (2 and 3) observations, to provide high spatio-temporal resolution LST estimates in cities

Limitations in the Use of the Equivalent Diameter

This paper deals with the inaccuracy assessment of the friction pressure loss estimation based on Darcy formula combined with an equivalent hydraulic diameter and a friction factor valid for circular pipes when applied to a square rod bundle. The assessment has been done by comparing the analytical and semi-empirical predictions with two different CFD codes results: CFX and NEPTUNE_CFD. Two different analytical approaches have been considered: the whole-bundle and sub-channel approaches, both for laminar and turbulent flow conditions. Looking at results, it is reasonable to assume that an error in the range of 11% - 23% is likely when using equivalent diameter in the laminar regime. In the case of turbulent regime, the equivalent diameter works better and the error is in the range between a few percent and ~12%

Unmet needs in ANCA-associated vasculitis: Physicians’ and patients’ perspectives

In recent years, clinical research has increased significantly and therapies for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis have improved. However, there are still unanswered questions and unmet needs about AAV patients. The purpose of this review is to examine the frontiers of research related to emerging biomarkers eventually predicting relapse, and new therapeutic approaches, not to mention new quality of life assessment tools. Identifying predictors of relapse may help optimize therapeutic strategies, minimize disease recurrence, and reduce treatment-related side effects. In addition, it is important to recognize that patients may suffer long-term consequences of the disease and its treatment, which, although life-saving, is often associated with significant side effects. Our goal, therefore, is to highlight what has been achieved, the pitfalls, and what still needs to be done, comparing the views of physicians and patients

Ramp rate abatement for wind energy integration in microgrids

This study analyses the performance of a battery storage system in abating the ramp rates of the power produced by a wind turbine. This approach can reduce the wind power fluctuations that are typical of small size wind farms and promote the wind energy integration in microgrids. Production data was generated from actual wind measurements over one year, and the capability of ramp abatement by varying battery capacity, battery power rating and ramp rate thresholds was investigated. The effect on battery degradation due to charge-discharge cycling required by the smoothing service was also estimated. Results suggest that good smoothing performance can be achieved with a wide range of power-capacity combinations, but the lifetime of the storage system can be as low as one year if its capacity is small

COSMO-SkyMed potential to detect and monitor Mediterranean maquis fires and regrowth: a pilot study in Capo Figari, Sardinia, Italy

Mediterranean maquis is a complex and widespread ecosystem in the region, intrinsically prone to fire. Many species have developed specific adaptation traits to cope with fire, ensuring resistance and resilience. Due to the recent changes in socio-economy and land uses, fires are more and more frequent in the urban-rural fringe and in the coastlines, both now densely populated. The detection of fires and the monitoring of vegetation regrowth is thus of primary interest for local management and for understanding the ecosystem dynamics and processes, also in the light of the recurrent droughts induced by climate change. Among the main objectives of the COSMO-SkyMed radar constellation mission there is the monitoring of environmental hazards; the very high revisiting time of this mission is optimal for post-hazard response activities. However, very few studies exploited such data for fire and vegetation monitoring. In this research, Cosmo-SkyMed is used in a Mediterranean protected area covered by maquis to detect the burnt area extension and to conduct a mid-term assessment of vegetation regrowth. The positive results obtained in this research highlight the importance of the very high-resolution continuous acquisitions and the multi-polarization information provided by COSMO-SkyMed for monitoring fire impacts on vegetation

Probing Liquid-Ordered and Disordered Phases in Lipid Model Membranes: A Combined Theoretical and Spectroscopic Study of a Fluorescent Molecular Rotor

An integrated theoretical/experimental strategy has been applied to the study of environmental effects on the spectroscopic parameters of 4-(diphenylamino)phtalonitrile (DPAP), a fluorescent molecular rotor. The computational part starts from the development of an effective force field for the first excited electronic state of DPAP and proceeds through molecular dynamics simulations in solvents of different polarities toward the evaluation of Stokes shifts by quantum mechanics/molecular mechanics (QM/MM) approaches. The trends of the computed results closely parallel the available experimental results thus giving confidence to the interpretation of new experimental studies of the photophysics of DPAP in lipid bilayers. In this context, results show unambiguously that both flexible dihedral angles and global rotations are significantly retarded in a cholesterol/DPPC lipid matrix with respect to the DOPC matrix, thus confirming the sensitivity of DPAP to probe different environments and, therefore, its applicability as a probe for detecting different structures and levels of plasma membrane organization

Volcanic cloud detection using Sentinel-3 satellite data by means of neural networks: the Raikoke 2019 eruption test case

The accurate automatic volcanic cloud detection by means of satellite data is a challenging task and of great concern for both scientific community and stakeholder due to the well-known issues generated by a strong eruption event in relation to aviation safety and health impact. In this context, machine learning techniques applied to recent spaceborne sensors acquired data have shown promising results in the last years. This work focuses on the application of a neural network based model to Sentinel-3 SLSTR (Sea and Land Surface Temperature Radiometer) daytime products in order to detect volcanic ash plumes generated by the 2019 Raikoke eruption. The classification of the clouds and of the other surfaces composing the scene is also carried out. The neural network has been trained with MODIS (MODerate resolution Imaging Spectroradiometer) daytime imagery collected during the 2010 Eyjafjallaj&ouml;kull eruption. The similar acquisition channels of SLSTR and MODIS sensors and the events comparable latitudes foster the robustness of the approach, which allows overcoming the lack in SLSTR products collected in previous mid-high latitude eruptions. The results show that the neural network model is able to detect volcanic ash with good accuracy if compared with RGB visual inspection and BTD (Brightness Temperature Difference) procedure. Moreover, the comparison between the ash cloud obtained by neural network and a plume mask manually generated for the specific SLSTR considered images, shows significant agreement. Thus, the proposed approach allows an automatic image classification during eruption events, which it is also considerably faster than time-consuming manually algorithms (e.g. find the best BTD product-specific threshold). Furthermore, the whole image classification indicates an overall reliability of the algorithm, in particular for meteo-clouds recognition and discrimination from volcanic clouds. Finally, the results show that the NN developed for the SLSTR nadir view is able to properly classify also the SLSTR oblique view images.</p