177,411 research outputs found
Environmental impact assessment of R-152a as a drop-in replacement of R-134a in a domestic refrigerator
No full textIn the European Union F-gas Regulation limited the use of some refrigerants in several applications. Regarding the domestic refrigeration sector, the F-gas Regulation banned the use of refrigerants with GWP values higher than 150. This fact led the scientific community to search for a replacement of R-134a, that is the most common refrigerant used in domestic refrigerators in USA. In this work, a comprehensive environmental analysis of the drop-in substitution of R-134 with a low GWP refrigerant (R-152a) in a no-frost domestic refrigerator was performed. The comparison, based on experimental data, between the environmental performance of the refrigeration system with the two refrigerants was carried out developing two different evaluation methods, which led to the evaluation of TEWI and LCCP, respectively. Both these metrics consider both direct and indirect contributions to global warming. Historical data of different countries were used to forecast the carbon intensity values for the next 15 years, which were then used to evaluate indirect emissions of the system during its lifetime. Considering the Italian case study, the results showed that the refrigerator working with an optimal charge of R-152a, identified as the mass charge that minimises TEWI and/or LCCP index, has better environmental performance than the system working with R-134a, with a reduction of TEWI and LCCP values of 10.3% and 9.4%, respectively. The same comparison, in terms of LCCP, was also performed for other European countries, showing a strong dependence of the LCCP index on carbon intensity values
An experimental evaluation of the vapour compression plant performances in presence of R407C leaks using an electronic expansion valve
No full textExperimental evaluation of electronic and thermostatic expansion valves performances using R22 and R407C
No full textTreatment of morbid obesity with intragastric balloon: BioEnterics intragastric vs. Spatz adjustable balloon systems
No full textA draft genome sequence of an invasive mosquito: An Italian Aedes albopictus
No full textThe draft genome sequence of Italian specimens of the Asian tiger mosquito Aedes (Stegomyia) albopictus (Diptera: Culicidae) was determined using a standard NGS (next generation sequencing) approach. The size of the assembled genome is comparable to that of Aedes aegypti; the two mosquitoes are also similar as far as the high content of repetitive DNA is concerned, most of which is made up of transposable elements. Although, based on BUSCO (Benchmarking Universal Single-Copy Orthologues) analysis, the genome assembly reported here contains more than 99% of protein-coding genes, several of those are expected to be represented in the assembly in a fragmented state. We also present here the annotation of several families of genes (tRNA genes, miRNA genes, the sialome, genes involved in chromatin condensation, sex determination genes, odorant binding proteins and odorant receptors). These analyses confirm that the assembly can be used for the study of the biology of this invasive vector of disease. © W. S. Maney & Son Ltd 2015
Performances of thermostatic and electronic valves controlling the compressor capacity
No full textThe performance of the energy consumption of an electronic valve and a classical thermostatic valve has been compared when these expansion valves are adopted in a vapour compression plant subjected to a cold store. The main aim is to verify experimentally which type of expansion valve would be preferable from energy point of view when a classical thermostat or a fuzzy logic algorithm are used as the control system for the refrigeration capacity. The fuzzy logic-based control is able to modulate continuously the compressor speed through an inverter. The results show that with a fuzzy algorithm, the thermostatic expansion valve allows an energy saving of about 8% in comparison with the electronic valve. When on–off control is used, the electric energy consumption obtained both with the electronic valve and with the thermostatic valve is comparable
Experimental Evaluation of R22 and R407C Pressure Drop During Horizontal Annular Flow Boiling
No full textAn experimental investigation on optimal heat rejection pressure for a carbon dioxide split system
No full textHydrodynamic characterization of "gulf stream" circulation in a pilot scale fluidized bed combustor
No full textThe present study addresses the hydrodynamics of a pilot-scale fluidized bed combustor with a focus on the establishment of "Gulf Stream" circulation patterns as a solids mixing promoter. Time-resolved pressure signals measured at different locations in the bed and in the plenum were analyzed in the time, frequency and phase-space domains. Results were matched against qualitative characterization of fluidization patterns by visual observation of the bed surface
Change in energy performance as a result of a R422D retrofit: an experimental analysis for a vapor compression refrigeration plant for a walk-in cooler.
No full textIn this paper, the energy performance of a walk-in cooler working with R22 and its substitute R422D are
experimentally studied. The experimental investigation was carried out considering three different operating
conditions; in particular, the AHRI standard has been used as reference for operating conditions. All
tests were run at steady state conditions and keeping the external air temperature at 35 C. The experimental
analysis allowed the determination of cooling capacity, the electrical power absorbed, the COP
and other variables characterizing the working of the plant. The results demonstrated that the cooling
capacity for R422D was lower than for R22, while the electrical power absorbed with R422D was higher
than that with R22. As consequence, the COP of R422D was lower than that of R22. Furthermore, technical
proposals are introduced with the aim of improving the overall performances of those plants, which
could be retrofitted with R422D
- …
