Search results for "ventilation"
showing 10 items of 476 documents
PCM thermal storage design in buildings: Experimental studies and applications to solaria in cold climates
2017
Abstract As energy availability and demand often do not match, thermal energy storage plays a crucial role to take advantage of solar radiation in buildings: in particular, latent heat storage via phase-change material is particularly attractive due to its ability to provide high energy storage density. This paper analyzes the performance of a building-integrated thermal storage system to increase the energy performances of solaria in a cold climate. A wall opposing a highly glazed facade (south oriented) is used as thermal storage with phase change materials embedded in the wall. The study is based on both experimental and simulation studies. The concept considered is particularly suited t…
Redesign of a Rural Building in a Heritage Site in Italy: Towards the Net Zero Energy Target
2017
In order to achieve the ambitious objective of decarbonising the economy, it is mandatory, especially in Europe and in Italy, to include the retrofitting of existing buildings. In a country where a large share of existing buildings have heritage value, it is important to design effective retrofit solutions also in historical buildings. In this context, the paper describes the experience of re-design of an existing rural building located in Sicily, inside the ancient Greeks' “Valley of the Temples”. An energy audit was performed on the building, and its energy uses were thoroughly investigated. A building model was developed in the TRNSYS environment and its performances validated. The valid…
A preliminary method for the numerical prediction of the behavior of air bubbles in the design of Air Cavity Ships
2016
Air-cavity ships (ACS) are advanced marine vehicles that use air injection under hull to improve the vessel’s hydrodynamic characteristics. Although the concept of drag reduction by supplying gas under the ship’s bottom was proposed in the 19th century by Froude and Laval, at this time there are not many systematic studies on this subject. This paper is a preliminary work with the purpose of being a basic tool for the design of the ACS with computational fluid dynamic methods. The study aims to conduct a series of computational tests to compare the numerical models of bubble with experimental data. The first step of this study was to investigate the behavior of free bubble in water, conside…
Absorption equipment for energy savings: A case study in Sicily
2013
Abstract This paper considers a feasibility study on the recovery of the reject heat available from an electric utility with two units operating with 120-MW gas turbines; these units have a heat recovery system that feeds the district heating pipeline of an industrial consortium. Thus, feeding the expeller of the absorption equipment installed in a cooling plant for foodstuff stocking represents an opportunity for the feasibility study. This plant operates at both 0 °C and −18 °C. The feasibility study covers two aspects: (1) the technical feasibility of a suitable absorption cooling plant that uses two separate pieces of absorption equipment working with the pair ammonia–water and (2) the …
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…
Air quality and relative humidity in commercial aircrafts: an experimental investigation on short-haul domestic flights
2013
Abstract Nowadays the achievement of a comfortable environment in aircraft cabins is a factor of paramount importance in air travel business competition; on the other hand, the need of reducing the propulsion fuel cost has driven the airline companies to adopt air handling systems that may reduce the levels of thermal comfort and air quality inside the cabins of commercial airliners. With the aim of contributing to a better knowledge of this matter, this paper reports the results of an experimental study upon the indoor air quality aboard commercial aircrafts for 14 domestic flights less than 1 h and half long. The parameters monitored were temperature, relative humidity and carbon dioxide …
APPLICATION OF MATHEMATICAL MODELS FOR THE SIMULATION OF THERMAL COMFORT CONDITIONS IN A LIVING ROOM
2005
The paper deals with the distributions of temperature and averaged turbulent airflows in living rooms in 2D and 3D approximations using Ansys/Flotran and Ansys/CFX software respectively. The distributions are calculated depending on the placement and temperature of heaters, heat transfer coefficients of the building structures and ventilation conditions. The authors analyse the influence of these factors on the air circulation and the related heat flows through building structures. The thermal balance of a room and its dependence on various external factors is also considered. As thermal comfort conditions’ parameters are analysed, the airflow velocities and indoor temperatures with its gra…
Impact of wind speed on ventilation performance within a container installed with photovoltaic inverter
2017
Abstract PV inverter needs proper ventilation for reducing the heat dissipation of the electronic components. In this work, a container installed with PV inverter is considered with different configurations of cooling channels within the container for ventilation analysis. Typically, high capacity PV inverters are installed inside the container and therefore inverters, are not experiencing external wind effects and it depends on the configuration of cooling channels. In this work, the main cooling channel is located at the top of the inverter; inlet and outlet ventilation holes are located on the side of cross ventilation. They help in analyzing the cooling design, dependent on site specifi…
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 …