The aim of this paper is to determine the heat of combustion of plastic wastes resulted from municipal solid waste, automotive shredder facility waste and building and construction waste. The plastic wastes have been separated by flotation technique using as flotation media: water, ethanol, their mixtures and magnetic fluid. Resulted fractions have been analyzed aiming to determine the most effective fraction from the heat of combustion point of view. The obtained results have been compared to those reported in the literature, with those calculated by oxygen consumption method and those proposed in this paper and calculated by weighted sum of combustion heat of components, aiming to allow its approximation for different fractions of polymeric wastes with known composition, avoiding the experimental measurements. Deviations of measured values of the heat of combustion from those obtained by theoretical calculation have been explained by the polymer degradation during their life cycle. The most effective fraction from calorific point of view is that containing polyolefins, but this fraction could be mechanically recycled. The present study evidenced that the heat of combustion of the plastic waste decreases after polyolefin extraction and the remaining density fractions can be effectively used for energy recovery of the plastic waste by incineration.
Improving the performance of internal combustion engines (ICE), together with lowering emissions, are the main targets for specialists in the automotive field. One option for increasing engine efficiency is creating a considerable amount of boost for the inlet combustion air by means of supercharging. In addition to common turbochargers, an alternative solution that has interested researchers for almost a century is the pressure wave supercharger (PWS). This paper is, at first, a complimentary tribute to most of the researchers that studied, experimented with and improved PW supercharging technology from the 50′s to the present. Second, this review emphasizes the performance achieved by ICEs when using PW supercharging, highlighting the limits of these main parameters in different operating conditions, based on the main reported results in the literature. It also provides an overview of PW supercharging technology, with its main advantages and disadvantages and suggests some technical solutions or geometric adjustments to improve its operation. Even though in recent years this technology has registered a decrease of interest, there are still preoccupations, especially in the aeronautical industry, justified by the profitability and simplicity of PW devices. The results of this theoretical work can be exploited practically in PWS design and applications.
The paper aims at a numerical investigation of the evolution of velocity, pressure and temperature field along the wave rotor channels for a pressure wave supercharger. Since in literature most of the studies are made considering the working fluid as incompressible and inviscid in a 2D field, the present study is using the compressible and viscous terms in unsteady Navier-Stokes equations for fluid in 3D field. The geometry was drawn in CAD software using measurements made on a real model of the CX-93 pressure wave supercharger. The simulation was conducted using a CFD code for unsteady 3D k-e, k-co model approach to reproduce data such as pressures, temperature and mass flows which are usually measured in real engine pressure wave supercharging. The computational domain for uRANS was modeled as a moving rotational domain with adaptive meshing. Results such as velocity, pressure and temperature field in the rotor channels were obtained for exhaust gas inlet pressure of 0.28 MPa and 1465 K temperature at different rotational speeds. The air inlet state considered was: 0,098 MPa and 293 K. Supercharging by means of a pressure wave supercharger, in order to improve the performance of an internal combustion engine, appears to be a promising solution since the exhaust gas generates a benefice boost of intake air with significant advantages when compared to the conventional turbocharging. The numerical modelling of the complex phenomena occurring within the narrow channels might be a useful tool for improving the pressure exchange between the working fluids, either by modifying the input parameters or by optimizing the geometry of the rotor, ports or pockets.
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