1,720,979 research outputs found
Simulazione dinamica del sistema edificio-impianto: La procedura di validazione dei codici di calcolo
No full textStudio sperimentale sul deflusso di una soluzione LiBr-H2O irrorata su una colonna di tubi
No full textModeling and Adaptive Control of Low Capacity Chillers for HVAC Applications
No full textAn adaptive controller for single and uneven tandem scroll compressor, packaged air-cooled water
chillers is described. The designed controller allows to substantially increase the energy performance of
the system, as well as to achieve excellent regulation performances in process applications. The
controller parameters are adapted on the basis of estimates of the plant thermal load, that are computed
by using a Kalman filter. An ad hoc approach is used to define a relay control logic, which is based on
a numerical optimization procedure. To support controller design, a detailed simulation environment is
developed and validated on an experimental facility. Performance of the algorithm is described with
both simulation and experimental data. At low part load ratio values the proposed algorithm grants a
0.6e0.7 K improvement in the regulation performance in terms of supply water temperature standard
deviation and mean supply water temperature deviation. The unit energy efficiency improvement with
respect to supply water temperature control varies from 7.3% to 3.0% while the experimental seasonal
energy efficiency rating improvement is 9.1%
La CO2 negli impianti frigoriferi commerciali: valutazione energetica di diverse soluzioni impiantistiche per la reiezione del calore
No full textEnergy efficient control of HVAC systems with ice cold thermal energy storage
No full textIn heating, ventilation and air conditioning (HVAC) systems of medium/high cooling capacity, energy demands can be matched with the help of thermal energy storage (TES) systems. If properly designed, TES systems can reduce energy costs and consumption, equipment size and pollutant emissions. In order to design efficient control strategies for TES systems, we present a model-based approach with the aim of increasing the performance of HVAC systems with ice cold thermal energy storage (CTES). A simulation environment based on Matlab/Simulink® is developed, where thermal behaviour of the plant is analysed by a lumped formulation of the conservation equations. In particular, the ice CTES is modelled as a hybrid system, where the water phase transitions (solid-melting-liquid and liquid-freezing-solid) are described by combining continuous and discrete dynamics, thus considering both latent and sensible heat. Standard control strategies are compared with a non-linear model predictive control (NLMPC) approach. In the simulation examples model predictive control proves to be the best control solution for the efficient management of ice CTES systems
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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