Search results for "Heat Transfer"

Modeling the influence of potassium content and heating rate on biomass pyrolysis

2017

This study presents a combined kinetic and particle model that describes the effect of potassium and heating rate during the fast pyrolysis of woody and herbaceous biomass. The model calculates the mass loss rate, over a wide range of operating conditions relevant to suspension firing. The shrinking particle model considers internal and external heat transfer limitations and incorporates catalytic effects of potassium on the product yields. Modeling parameters were tuned with experimentally determined char yields at high heating rates (>200 K s−1) using a wire mesh reactor, a single particle burner, and a drop tube reactor. The experimental data demonstrated that heating rate and potassium …

Investigation of Surface Geology and Intensity Variability in the Palermo, Italy, Urban Area after the 6 September 2002 Earthquake

2005

For the first time, a high-density macroseismic survey has been carried out in the city of Palermo, Italy, after the 6 September 2002, Mw 5.9 earthquake. The aim was to investigate the spatial relationships and correlations between intensity data and surface geology. A very dense database has been created to store a large amount of macroseismic, stratigraphic, and geotechnical information. A Geographic Information Systems (gis) tool, called City-gis, enables data processing by instruments and research keys devoted to seismic hazard. The results show the feasibility of such procedures, especially for large cities where the surface geology critically influences the ground motion. Our analysis…

Radiative heat power at Stromboli volcano during 2000–2011: Twelve years of MODIS observations

2012

Abstract Twelve years of night-time MODIS (Moderate Resolution Imaging Spectroradiometer) observations, has been analysed to detect and quantify the radiative heat power emitted by Stromboli volcano (from March 2000 to September 2011). Using an accurate background subtraction of the MODIS signal at 4 μm, we were able to discriminate two main regimes of thermal radiation, related to different levels of volcanic activity. Effusive eruptions (occurred on December 28, 2002 and February 27, 2007) radiated at an average of ~ 186 MW with a frequency of alert detection of 50–95%. Conversely, during the typical strombolian activity, an average of ~ 9 MW is radiated, with a frequency of alert detecti…

Low-Intensity Neutron Emission from TiDx Samples Under Nonequilibrium Conditions

2001

Several experiments were performed that loaded titanium samples with deuterium from the gas phase, changed the temperature of the samples over a wide range, and monitored the neutron emission. Neutron emissions in very low intensity bursts, still significantly above the background, were recorded, revealing that low-energy nuclear reactions in condensed matter can be produced at a very low rate, which occasionally can be high enough to become detectable.

k-epsilon Predictions of Heat Transfer in Turbulent Recirculating Flows Using an Improved Wall Treatment

1989

The boson peak of deeply cooled confined water reveals the existence of a low-temperature liquid-liquid crossover.

2014

International audience; The Boson peak of deeply cooled water confined in the pores of a silica xerogel is studied by inelastic neutron scattering at different hydration levels to separate the contributions from matrix, water on the pore surfaces and "internal" water. Our results reveal that at high hydration level, where the contribution from internal water is dominant, the temperature dependence of the Boson peak intensity shows an inflection point at about 225 K. The complementary use of differential scanning calorimetry to describe the thermodynamics of the system allows identifying the inflection point as the signature of a water liquid-liquid crossover.

Increasing the drying efficiency of cylinder drying

2011

This PhD Thesis concentrates on paper drying: first on the drying rate in a cylinder covered with fabric, enhanced using hot air impingement through the fabric, and its potential effects on paper quality, and second, on the heat transfer rate from hot steam to paper through the cylinder shell. Cylinder drying is a drying method where a heated surface in contact with paper causes water removal from the latter by evaporation. Impingement through the fabric of hot air has been suggested to cause increase in the water removal and drying of paper. Increase in the drying rate by impingement of hot air was confirmed by laboratory tests and by simulations. In laboratory tests the increase in the dr…

Omni-Channel Intensity and Shopping Value as Key Drivers of Customer Satisfaction and Loyalty

2021

Omni-channel retailing consists of the complete alignment of the different channels and touchpoints that generate a seamless experience for consumers, allowing them to move freely through all channels. The consumer's perception of a seamless and consistent omni-channel experience is called intensity. This study reveals that this intensity in the shopping experience can offer value to consumers, and that intensity and shopping value also influence satisfaction and loyalty. We propose a relationship model that had been tested in a quantitative study with PLS, with a representative sample of buyers who had used the Click and Collect system. The main contribution of this study is to the literat…

Performance Dissimilarities in European Union Manufacturing: The Effect of Ownership and Technological Intensity

2021

Our paper addresses the relevance of a set of continuous and categorical variables that describe industry characteristics to differences in performance between foreign versus locally owned companies in industries with dissimilar levels of technological intensity. Including data on manufacturing sector performance from 20 European Union member countries and covering the 2009–2016 period, we used the random forests methodology to identify the best predictors of EU manufacturing industries’ a priori classification based on two main attributes: ownership (foreign versus local) and technological intensity. We found that EU foreign-owned businesses dominate locally owned ones in terms of size, wh…

Modelling flow and heat transfer in spacer-filled membrane distillation channels using open source CFD code

2013

Abstract A good understanding of the details of hydrodynamic and heat transport conditions and their impact on temperature polarisation and pressure drops is essential for optimum design of membrane distillation (MD) modules. To this end, the present work reports on initial progress in the development of a tool for 3D simulation of spacer-filled MD channels based on the open source CFD code library OpenFOAM. The paper discusses a number of modelling and implementation aspects including model geometry and computational domain, choice of boundary conditions, and discretisation schemes. The results pertaining to the effect of three different spacer types on the fluid dynamics and heat transfer…