1,721,008 research outputs found
Maximization of primary energy savings of solar heating and cooling systems by transient simulations and computer design of experiments
No full textIn this paper, the simulation of the performance of solar-assisted heating and cooling systems is analyzed.
Three different plant layouts are considered: (i) the first one consists of evacuated solar collectors and a
single-stage LiBr–H2O absorption chiller; here in order to integrate the system in case of insufficient solar
radiation, an electric water-cooled chiller is activated; (ii) configuration of the secondly considered system
is similar to the first one, but the absorption chiller and the solar collector area are sized for balancing
about 30% of the building cooling load only; (iii) the layout of the thirdly considered system differs from
the first one since the auxiliary electric chiller is replaced by a gas-fired heater. Such system configurations
also include: circulation pumps, storage tanks, feedback controllers, mixers, diverters and on/off
hysteresis controllers.
All such devices are modelled for maximizing the system energy efficiency. In order to simulate the
systems’ performance for dynamic heating/cooling loads, a single-lumped capacitance building is also
modelled and implemented in the computer code. A cost model is also developed in order to calculate
the systems’ operating and capital costs. All the models and the relative simulations are carried out by
TRNSYS. A design of experiment procedure is also included. By such tool the effects of the system
operating parameters’ variation on the relative energy efficiency are analyzed. In addition, the set of
synthesis/design variables maximizing the system’s energetic performance can be also identified.
The annual primary energy saving is chosen as the optimization objective function, whereas collector
slope, pump flows, set-point temperatures and tank volume are selected as optimizing system design
variables.
A case study was developed for an office building located in South Italy. Here, the energetic and the
economic analysis for all the three considered system layouts are carried out. The simulations’ results
are referred to both the initial and the optimized systems configurations. The highest primary energy
saving vs. the reference traditional HVAC system is reached by the first considered system layout. The
economic performance of the investigated solar heating/cooling systems is still unsatisfactory. The economical
profitability of the considered solar heating and cooling systems can be improved only by significant
public finding. From this point of view, the best results were achieved by the second above
mentioned system configuration
Design optimisation of the condenser in vapour compression heat pumps by thermoeconomic analysis
No full text
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
Energetic and environmental analysis of a domestic scale heat pump driven by a micro-cogenerator
No full textDynamic simulation and energetic-economic analysis of a polygeneration system based on pem fuel cells and concentrated photovoltaic-thermal collectors
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