Search results for "HVAC"
showing 10 items of 56 documents
The spatial evaluation of the radiative human body heat exchanges: An effective contribution for limiting energy consumption and achieving better ind…
2018
Abstract Radiative heat exchanges inside buildings remarkably affect the thermal balance of the human body in confined spaces and the related thermal comfort sensations of people. The mean radiant temperature is an important component of this balance. Unfortunately, it is usually computed by means of too simplified relationships, which significantly influence the comfort evaluations. Such simplified approaches are also accountable for a less effective design of HVAC systems which, in turn, could result in high energy consumption in the climatization of buildings. However, an accurate evaluation of the mean radiant temperature, especially when high intensity sources are present in a given in…
A Check of Water Drop Impact Effects on Surface Soil Saturated Hydraulic Conductivity
2020
The post-tillage dynamics of the surface soil saturated hydraulic conductivity, Ks, was studied at the Masse experimental station (central Italy, silty-clay-loam soil). A sequence of experiments was performed by rainfall simulation on two replicated micro-plots (width 1 m, length 0.92 m, slope 16%) established on bare soil. Each high-intensity rainfall simulation was preceded by a low-intensity wetting phase. The soil water content, w, was measured before wetting and both before and after simulation. Runoff was measured at 5 min intervals. The infiltration rate was calculated as the difference between rainfall intensity and runoff rate. Finally, Ks was assumed to be equal to the infiltratio…
Comparing Beerkan infiltration tests with rainfall simulation experiments for hydraulic characterization of a sandy-loam soil
2017
[EN] Saturated soil hydraulic conductivity, K-s, data collected by ponding infiltrometer methods and usual experimental procedures could be unusable for interpreting field hydrological processes and particularly rainfall infiltration. The K-s values determined by an infiltrometer experiment carried out by applying water at a relatively large distance from the soil surface could however be more appropriate to explain surface runoff generation phenomena during intense rainfall events. In this study, a link between rainfall simulation and ponding infiltrometer experiments was established for a sandy-loam soil. The height of water pouring for the infiltrometer run was chosen, establishing a sim…
Modelling Indoor Radiative Heath Exchanges for Effective People Thermal Comfort and HVAC Design.
2017
Radiative heat exchanges inside buildings are responsible of a relevant part of the thermal balance of people occupying such confined spaces and, in turn, of their thermal comfort sensations. Mean radiant temperature of the internal surfaces is supposed to affect considerably this balance but, usually, it is computed by means of too simplified relationships that significantly affect the comfort evaluations. These simplified approaches can be also accountable of a less effective design of HVAC systems. Unfortunately, an accurate evaluation of the mean radiant temperature, especially when high intensity sources are present in a given internal space, depends on the angle factors between human …
Monitoring and energy performance assessment of an advanced DEC HVAC system in Morocco
2017
This work addresses the energy performance of a solar Desiccant and Evaporative Cooling (DEC) system working with the freescoo technology. Freescoo is an innovative solar air conditioning concept for ventilation, cooling, dehumidification and heating of buildings in residential and tertiary sectors. The monitoring of the system started in November 2016 and will continue until the end of 2017. Energy performances are evaluated according to the monitoring procedure for solar cooling systems developed by the Task 38 and 48 of the International Energy Agency experts. The analysis based on monitoring data shows that, for typical operating conditions in cooling mode, the electricity saving in com…
Programming distributed applications with symbolic reasoning on WSNs
2015
Programming Wireless Sensor Networks (WSNs) is a complex task for which existing approaches adopt rigid architectures that are only suitable for specific application fields. In previous papers we introduced a programming methodology and a lightweight middleware based on high-level programming and executable code exchange for distributed processing on WSNs. In this paper, we show how high-level programming can be effectively used on WSNs to implement symbolic reasoning. In order to prove the feasibility of our approach, we present a Fuzzy Logic system where the value updates and the rule evaluations are performed in a distributed way. Through the proposed methodology, we discuss the developm…
Testing steady-state analysis of single-ring and square pressure infiltrometer data
2016
Testing reliability of the saturated soil hydraulic conductivity, Ks, estimated by applying the steady-state single-ring (SR) model to the quasi steady-state infiltration rates obtained with a single-ring pressure infiltrometer (PI) increases confidence in the estimated Ks values. Determining a means to estimate Ks from infiltration data collected with a square infiltrometer allows the use of sources of different shapes. Using numerically simulated infiltration rates for six homogeneous soils ranging in texture from sand to silty clay loam, this investigation suggested an overall good performance of the SR model, with estimated Ks values differing by not more than 25% from the true values f…
Testing an adapted beerkan infiltration run for a hydrologically relevant soil hydraulic characterization
2020
Abstract Literature raises doubts about the usability of infiltrometer methods to characterize soils in a hydrological perspective since these methods often yield excessively high infiltration rates or saturated soil hydraulic conductivity, Ks, values. For a loam (AR) and a silty-clay (RO) soil, beerkan infiltration runs were adapted in the perspective to obtain usable soil data to predict rainfall partition into infiltration and rainfall excess. In particular, the initially nearly dry soil was sampled with different water volumes (15 or 30) and heights of water application (low, L, 0.03 m, and high, H, 1.5 m), and the BEST-steady algorithm was applied to determine sorptivity, S, and Ks. Th…
Superconducting Microwave Cavity Made of Bulk MgB2
2006
We report the successful manufacture and characterization of a microwave resonant cylindrical cavity made of bulk MgB2 superconductor (Tc = 38.5 K), which has been produced by the Reactive Liquid Mg Infiltration technique. The quality factor of the cavity for the TE011 mode, resonating at 9.79 GHz, has been measured as a function of the temperature. At T = 4.2 K, the unloaded quality factor is 2.2x10^5; it remains of the order of 10^5 up to T ~ 30 K. We discuss the potential performance improvements of microwave cavities built from bulk MgB2 materials produced by reactive liquid Mg infiltration.
Seasonal changes of the infiltration rates in a Mediterranean scrubland on limestone
1997
To investigate the seasonal changes of infiltration rates, measurements by means of simulated rainfall experiments and cylinder infiltrometer were done in a small E–W oriented watershed in Southeast Spain. Data were collected during both the wet seasons (autumn, winter and spring) and the dry season (summer). Infiltration rates were very high in summer, when direct surface runoff is very low. During the wet seasons, the infiltration rates were lower due to the increase in soil moisture. Measurements by means of both ponding as well as simulated rainfall are suitable to study the infiltration process. The former needs more replications, due to the small observation area encompassed for each …