Linear Compressor Discharge Manifold Design For High Thermal Efficiency

In the design of hermetic compressors for household refrigeration, one important part of the overall efficiency of the machine comes from a good thermal efficiency of the discharge manifold. It is desired that the heat generated during the compression process and accumulated by the gas in the discharge chamber does not return to the compression chamber walls. If not, this heat returns to the pump, reducing volumetric efficiency. Current technologies like on/off and variable velocity compressors, normally make use of metallic parts in the discharge chamber, such parts having high thermal conduction coefficients making them less efficient. Linear compressor technology, together with the non-use of oil allows the improvement of the discharge manifold system, increasing the thermal insulation of the heat from discharge chamber to compression chamber, improving efficiency. This article aims to show the development of this improved discharge system, tests performed, and results obtained

Estação de tratamento de dejetos de suínos (ETDS) como alternativa na redução do impacto ambiental da suinocultura.

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Invasive Crayfish moving Northwards: management challenges and policy implications at the local scale

Freshwater ecosystems in Italy, as most European countries, have been severely impacted by the invasion of alien crayfish. The two most widespread species in Trentino (NE Italy) are Procambarus clarkii and Faxionus limosus; for both species, the high elevation and cold climate of most of the Trentino territory represent a climatic barrier to their northwards spread. Procambarus clarkii is present in one small lake at 950 m asl, and Faxionus limosus in a group of 5 lakes at 450 m asl, over an area of about 80km2. the introduction of both species is associated with fish restocking, and lead to the extinction of existing populations of the native stone crayfish Austropotamobius pallipes. The Management Plan of Austropotamobius pallipes in Trentino listed the eradication/containment of these IAS populations among the conservation priorities for the native populations. The eradication campaigns of P. clarkii started in 2018 with a release/recapture campaign aimed at assessing the abundance of the populations, and continued in 2020, 2021, 2022. As a result, the capture efficiency decreased, suggesting a population reduction trend. The containment of Faxionus limosus is more difficult, given its presence in a higher number of lakes, three of which are hydrologically connected. A first containment campaign to prevent its spread in the river network is planned for summer 2023. The financial support to these activities has been granted by the local Nature 2000 networks and by the local administrations, which have also promoted the communication with citizens and stakeholders to raise consensus and collaboratio

A REDUCED KINETIC MECHANISM FOR PROPANE FLAMES

Propane is one of the simplest hydrocarbons that can be a representative of higher hydrocarbons used in many applications. Therefore, this work develops a ten-step reduced kinetic mechanism among 14 reactive species for the propane combustion. The model is based on the solution of the flamelet equations. The equations are discretized using the second-order space finite difference method, using LES (Large-Eddy Simulation). Obtained results compare favorably with data in the literature for a propane jet diffusion flame. The main advantage of this strategy is the decrease of the work needed to solve the system of governing equations

Evaluation of Competencies for a Sustainable Industrial Environment

The organisation of worker activities in manufacturing shops have been differently conceived depending on political, societal, environmental and economic circumstances affecting industrial development. From Taylorism and Fordism through Lean Manufacturing to the innovative Cell Production system, the level and quality of abilities and competencies of workers have increasingly become the kernel of factory management models. Sustainability has increasingly become a crucial factor for product success. The design and manufacture of industrial products are conceived in circular loops within the 6R framework. The digitalisation of information has allowed significant advancements. Qualified and skilled operators have accompanied and led these evolutions, and their abilities and creativity have grown relevant, despite the continuous increase in automation. This work investigates the contribution of craftsmanship abilities in the industrial environment. For this purpose, the Craftsmanship Index has been proposed to assign a quantitative value to the craftsmanship skills contributing to the manufacturing activities. A customised questionnaire to be administered to workers is used to calculate this index, which is helpful to analyse worker abilities and the way they are learned and developed, being part of effective management and decision-making tools. A case study in the Japanese manufacturing environment expands on previous results achieved in Italy. The Craftsmanship Index allowed us to give a quantitative relevance to the level of abilities of operators depending on the analysed department. Some cultural differences have also emerged thanks to the comparison between the Japanese and the Italian culture

Linear Compressor Suction Valve Optimization

Design of hermetic compressors for household refrigeration follows a common sequence that considers an initial concept, normally based on existing families. Those are then upgraded with new features, aiming improvements in efficiency, sound quality or even cost reduction. Common compressors have a cylinder head that carries discharge and suction valve. In a new and compact designs for linear compressor suction valve is placed on the top of the piston, requiring new shapes in order to make it possible to satisfy, gas flow, fatigue and dynamics requirements. This article aims to present the use of optimization procedure used to develop the suction valve design for a linear compressor, the results obtained with the optimization process, and final results in compressor, in terms of performance and noise

MOCRA: a Monte Carlo code for the simulation of radiative transfer in the atmosphere.

This paper describes the radiative transfer model (RTM) MOCRA (MOnte Carlo Radiance Analysis), developed in the frame of DOAS (Differential Optical Absorption Spectroscopy) to correctly interpret remote sensing measurements of trace gas amounts in the atmosphere through the calculation of the Air Mass Factor. Besides the DOAS-related quantities, the MOCRA code yields: 1- the atmospheric transmittance in the vertical and sun directions, 2- the direct and global irradiance, 3- the single- and multiple- scattered radiance for a detector with assigned position, line of sight and field of view. Sample calculations of the main radiometric quantities calculated with MOCRA are presented and compared with the output of another RTM (MODTRAN4). A further comparison is presented between the NO2 slant column densities (SCDs) measured with DOAS at Evora (Portugal) and the ones simulated with MOCRA. Both comparisons (MOCRA-MODTRAN4 and MOCRA-observations) gave more than satisfactory results, and overall make MOCRA a versatile tool for atmospheric radiative transfer simulations and interpretation of remote sensing measurements

A multi-input UV-VIS airborne GASCOD/A4r spectroradiometer for the validation of satellite remote sensing measurements

The present paper describes a UV-VIS spectroradiometer named GASCOD/A4r developed at ISAC-CNR for remote sensing measurements aboard stratospheric M55-Geophysica aircraft, flying up to 21 km. Obtained experimental data are used for retrieving of NO2, O3 and of other minor gases atmospheric content, applying the DOAS (Differential Optical Absorption Spectroscopy) method. UV actinic flux and J(NO2) are also derived. All these parameters are used for satellite data validation tasks. The specific results obtained during dedicated aircraft missions in different geographical areas have already been utilized for ENVISAT validation

Assessment of a discontinuous galerkin method for the simulation of the turbulent flow around the drivaer car model

none7noThe turbulent flow over the DrivAer fastback model is here investigated with an orderadaptive discontinuous Galerkin (DG) method. The growing need of high-fidelity flow simulations for the accurate determination of problems, e.g., vehicle aerodynamics, promoted research on models and methods to improve the computational efficiency and to bring the practice of Scale Resolving Simulations (SRS), like the large-eddy simulation (LES), to an industrial level. An appealing choice for SRS is the Implicit LES (ILES) via a high-order DG method, where the favourable numerical dissipation of the space discretization scheme plays directly the role of a subgrid-scale model. Implicit time integration and the p-adaptive algorithm reduce the computational cost allowing a high-fidelity description of the physical phenomenon with very coarse mesh and moderate number of degrees of freedom. Two different models have been considered: (i) a simplified DrivAer fastback model, without the rear-view mirrors and the wheels, and a smooth underbody; (ii) the DrivAer fastback model, without rear-view mirrors and a smooth underbody. The predicted results have been compared with experimental data and CFD reference results, showing a good agreement.openColombo A.; Bortoli A.; Conti P.; Crivellini A.; Ghidoni A.; Nigro A.; Noventa G.Colombo, A.; Bortoli, A.; Conti, P.; Crivellini, A.; Ghidoni, A.; Nigro, A.; Noventa, G