Search results for " Ventilation"
showing 10 items of 372 documents
Phase Change Materials Applications to Optimize Cooling Performance of Buildings in the Mediterranean Area: A Parametric Analysis
2015
Abstract Building integrated thermal energy storage systems cover a wide range of techniques and solutions depending on technology applications and aims. They however all have in common the concept behind: being able to store energy for later use in order to reduce the time mismatch between energy availability and demand. In this context, Phase Change Materials (PCMs) fit the above description, since they would allow for mostly isothermal phase change within normal thermal comfort range. In order to face the typical challenges of the Mediterranean climate, the following concept was elaborated: the idea is to use the phase change mechanics as a substitute to the thermal inertia of massive wa…
Fire safety investigation for road tunnel ventilation systems – An overview
2014
Abstract In recent years, research activities about fire events in tunnel have received a significant impulse, especially after several accidents. The Computational Fluid Dynamic (CFD) has a fundamental role about. Researchers have spent resources on various topics involving numerical tools as the performance of a ventilation system, the influence of this on the air flow motion in the tunnel or the methods for fire schematization, fire-induced smoke characterization, turbulence models, etc. One of the main phenomena to consider for the safety when a fire occurs in a tunnel is the possibility of the fire-induced smoke to rise the tunnel (backlayering). A well-designed ventilation system shal…
Simulation model of a molten carbonate fuel cellemicroturbine hybrid system
2011
A Hybrid System based on High Temperature Fuel Cells coupled to a Microturbine allows a high efficiency, low environmental pollution and it may be exploited as a CHP System producing heat and electricity both Grid Connected and Stand Alone; the overall electrical efficiency could reach a very high value (up to 60%) and total efficiency could be over 70% including the contribution due to heat recovery. In the context of wide research activities of ENEA on High Temperature Fuel Cells and Hybrid Systems e that involve materials, system BoP and fuels e a very great effort has been devoted to design and build, in the ENEA Research Centre of “Casaccia”, an experimental Test-Rig based on a Molten …
Ventilation Rates and Unsatisfied Percentage from Indoor CO2 Concentration
2010
This work reports the results of a survey carried out on a hall in a historic building in Palermo (Italy) with the aim of assessing the air quality by means of objective measurement of carbon dioxide (CO2) concentration and its subjective evaluation through a questionnaire. The measured values of CO2 concentration were compared with those evaluated using the Meckler equation under steady-state conditions, having verified necessary parameters such as the constancy of the indoor and outdoor CO2 levels and the uniformity of the CO 2 generation rate for all the occupants. The positive correspondence between measured and calculated results allowed us to utilise, under differing circumstances, t…
Thermal analysis and new insights to support decision making in retrofit and relaxation of heat exchanger networks
2011
International audience; Pinch analysis offers a rational framework for identifying energy saving targets and designing efficient heat recovery networks, especially in process industry. Several scientists have contributed to improve and automate the original pinch method over the last decades, increasing its capability to deal with a number of specific issues; the expertise of the analyst, however, remains determinant in achieving optimal results. In this paper a procedure for retrofit of existing networks is proposed, based on an integrate use of several techniques (either existing or innovative). The diagnosis of the existing network and of a "Minimum Energy Requirement" configuration emer…
Ventilation-Perfusion Ratio in Perflubron During Partial Liquid Ventilation
2010
BACKGROUND: Functional magnetic resonance imaging (fMRI) of fluorine-19 allows for the mapping of oxygen partial pressure within perfluorocarbons in the alveolar space (Pao(2)). Theoretically, fMRI-detected Pao(2) can be combined with the Fick principle approach, i.e., a mass balance of oxygen uptake by ventilation and delivery by perfusion, to quantify the ventilation-perfusion ratio (Va/Q) of a lung region: The mixed venous blood and the inspiratory oxygen fraction, which are equal for all lung regions, are measured. In addition, the local expiratory oxygen fraction and the end capillary oxygen content, both of which may differ between the lung regions, are calculated using the fMRI-detec…
Results of heart retransplantation: subanalysis of the Spanish Heart Transplant Registry
2021
Heart retransplantation (ReHT) is controversial in the current era. The aim of this study was to describe and analyze the results of ReHT in Spain. Methods We performed a retrospective cohort analysis from the Spanish Heart Transplant Registry from 1984 to 2018. Data were collected on donors, recipients, surgical procedure characteristics, immunosuppression, and survival. The main outcome was posttransplant all-cause mortality or need for ReHT. We studied differences in survival according to indication for ReHT, the time interval between transplants and era of ReHT. Results A total of 7592 heart transplants (HT) and 173 (2.3%) ReHT were studied (median age, 52.0 and 55.0 years, respectively…
Akutes Lungenversagen bei Malaria tropica in der Schwangerschaft: Erfolgreiche Behandlung durch extrakorporale CO2-Elimination
2008
Eine 32jahrige Schwangere (26. Schwangerschaftswoche) erkrankte am 6. Tag nach der Ruckkehr von einem Indonesienaufenthalt mit Fieber bis 42°C, hamolytischer Anamie (Hamoglobin 7,6 g/dl) und Thrombozytopenie (7000/µl). Es wurde eine Malaria diagnostiziert; eine Prophylaxe hatte sie nicht durchgefuhrt. Unter antiparasitarer Chemotherapie mit Chloroquin, Chinin und Pyrimethamin kam es zur Elimination der Parasiten (Makrogametozyten von Plasmodium falciparum) aus dem peripheren Blut. Im weiteren Verlauf entwickelte sich jedoch ein progredientes Lungenversagen und eine therapierefraktare Pneumonie, die zu einem »adult respiratory distress syndrome« (ARDS; Morel-Stadium 4) fuhrten. Bei drohendem…
Impact of Circulatory Assistance in the Early Evolution After Heart Transplantation. Unicentric Experience.
2021
ABSTRACT Background Heart transplantation (HT) is the reference treatment for patients with terminal heart failure. In recent years there has been a progressive increase in HT procedures in patients who have a circulatory support (CS). Methods This is a retrospective single-center study of 293 consecutive patients who underwent HT from 2009 to 2018, analyzing the evolution of the 2 cohorts: patients with and without CS as a bridge to HT. Baseline and evolutionary clinical data collected following the usual follow-up protocol were recorded, including clinical events observed during the follow-up 1 year after the procedure. Results The subgroup of patients transplanted with CS showed a higher…
Analysis and modulation of the inflammatory response through lung agression related to bacterial infection and mechanical ventilation
2015
Despite major advances since decades in the management of ventilated patients, ventilator-associated pneumonia (VAP) continues to complicate the course of approximately 28% of the patients receiving mechanical ventilation (MV). Among patients hospitalized in intensive care units, the risk of pneumonia is 3- to 10- fold increased in MV patients. However, MV is often the only way to care for critically ill patients with respiratory failure. It has now been clearly demonstrated that MV, in particular adverse ventilatory strategies could activate lung cells, thus leading to a proinflammatory response, even in the absence of pathogen. This is the biotrauma paradigm, which accounts, at least in p…