1,721,082 research outputs found
Involucro trasparente. Oltre il concetto di isolamento termico. Dalle Double Skin Façade alle facciate altamente integrate
No full textTratto da "Perino M., Serra V., L'innovazione dell'involucro trasparente: oltre il concetto di isolamento termico, in Atti del 48° Convegno Internazionale AICARR 2011, Settembre 2011, Baveno, Italia
Short-term airing by natural ventilation - Modeling and control strategies (Indoor Air (2009) 19 (357-380))
No full textA stand-alone micro heat pump for personalized environmental control system (PECS)
Full text linkThis experimental study presents the design, development, and testing of a micro-scale vapor compression (VC) heat pump prototype tailored for novel Personalized Environmental Comfort Systems (PECS). The system employs a natural refrigerant (HC-290) to align with new environmental regulations, and integrates both compressor speed and expansion valve modulation, enabling continuous and precise control of cooling power and temperature – features rarely found in miniaturized systems. A key innovation is the integration of a 20-liter heat thermal energy storage unit (either sensible or latent) to buffer condensation heat and support standalone operation up to 8 h, without outdoor ducting or heat rejection. Experimental results show that localized cooling at approximately 20 °C can be maintained even in ambient conditions up to 36 °C, with an average Energy Efficiency Ratio (EER) of around 2 when using a latent heat thermal storage system based on phase change materials. The optimized configuration delivers a stable cooling output of ∼200 W, sufficient to meet the thermal needs of a single occupant while minimizing the impact on indoor air conditions. By reducing the volume of conditioned space and enabling direct user-level control, the proposed system supports a shift toward decentralized comfort solutions, with the potential to relax central HVAC setpoints and reduce overall building energy consumption. The study also provides a comprehensive experimental characterization
Low-Cost Tracer Gas Sensor for Building Ventilation
Full text linkThe accurate assessment of Indoor Air Quality is crucial for occupant health, yet traditional methods for evaluating ventilation rates, such as tracer gas techniques using photoacoustic spectroscopy (PAS), face limitations in cost, logistics, and response time. This study presents the development and validation of a low-cost, fast-response sensor system for tracer gas measurement, capable of detecting multiple gases. The sensor employs a Non-Dispersive Infrared (NDIR) detector with wireless communication based on the asynchronous Bleak protocol, enabling spatially resolved IAQ monitoring. Laboratory validation using SF6 as tracer gas in a small volume of 40 liters and against the PAS reference device demonstrated an accuracy within ±20% for ventilation rates between 1 and 7 air changes per hour (ACH). Unlike PAS, which provides one measurement per minute, the low-cost sensor captures up to 50 readings per second, offering superior tracking of transient ventilation events and dynamic IAQ variations. The results suggest that this system provides a practical alternative for real-time IAQ monitoring, supporting energy-efficient and health-conscious building management
Synthesis of acyclic carba-nucleoside phosphonates, structural analogues to natural deoxyribonucleotides
No full textAcyclic carba-nucleoside phosphonates, modelled on natural deoxyribonucleotides have been prepared starting from DNA nucleobases and tert-butyl acrylate. The products obtained from a Michael-type reaction were elongated to beta-oxo esters that were first reduced to beta-hydroxy esters and then transformed into protected beta-hydroxy aldehydes. Wittig-Horner-Emmons reaction with the anion of tetraisopropyl methylenebisphosphonate gave, after deprotection, the desired 4-hydroxy-6-purinyl- or -6-pyrimidinyl-1-hexenylphosphonic acids. A dimer, potential precursor of acyclic polynucleotides (APN), homomorphous with DNA, was also prepared
An Optimised Technique of the Batch Method for the Statistical Analysis of Simulation Results
No full textNumerical model for solar thermal collectors and thermal energy storages based on phase change slurry
Full text linkThe efficiency of conventional solar thermal collectors and related thermal energy storages is often reduced by the requirement for high irradiation levels and the heat losses due to the relatively high temperature of the heat transfer fluid. In order to overcome those limitations, a solar thermal system capable of working at low temperatures through the exploitation of latent heat storage is presented in this paper. The proposed system was based on a novel heat transfer fluid and storage media, composed by a mixture of water and micro-encapsulated phase change material (PCM), named Phase Change Slurry (PCS). This paper introduces a numerical model capable of accurately describe the physical process and the dynamics of the proposed technology (collector, thermal energy storage and control logics). Results were validated by means of experimental tests and a long-term monitoring on a real full-scale prototype. Furthermore, experimental tests were performed to carry out the actual PCS thermo-dynamical properties that are strongly dependent on the concentration of micro-capsules in the heat transfer fluid
Improving thermal performance of plasters by means of recycled and phase change materials
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