182 research outputs found
THERMODYNAMIC ORC CYCLE DESIGN OPTIMIZATION FOR MEDIUM-LOW TEMPERATURE ENERGY SOURCES
In the large spectrum of organic fluids suitable for Rankine cycles, a fluid that is already wellknown
and available on industrial scale but currently excluded from this kind of application
has been selected.
This choice is due to the remarkable characteristics of the fluid, such as its high molecular
weight, good thermal stability, non-flammability, and atoxicity.
Compared to those fluids nowadays common in the ORC market, its thermodynamic
properties and fluid dynamic behavior lead to a peculiar configuration of the cycle:
• Supercritical cycle, when heat input is at medium-high temperature;
• Massive regeneration, to obtain higher efficiency;
• Low specific work of the turbine;
• Relatively high volumetric expansion ratio and relatively low absolute inlet volumetric
flow;
Accordingly, an innovative cycle design has been developed, including a once-through
Hairpin primary heat exchanger and a multi-stage radial outflow expander.
This last innovative component has been designed to get the best performance with the chosen
fluid:
• The high inlet/outlet volumetric flow ratio is well combined with the change in cross
section across the radius;
• Compared to an axial turbine, the lower inlet volumetric flow is compensated by
higher blades at the first stage. It is feasible thanks to the change in section available
along the radius, so that there is no need for partial admission;
• The prismatic blade leads to constant velocity diagrams across the blade span;
• It minimizes tip leakages and disk friction losses, due to the single disk / multi-stage
configuration;
• The intrinsical limit of a radial outflow expander to develop high enthalpy drop is not
relevant for this cycle, presenting itself a very low enthalpy drop. Moreover the tip
speed is limited by the low speed of sound and consequently this kind of expander
suits well with this cycle arrangement.
The results of this study, conducted through thermodynamic simulations, CFD, stress analysis
and economic optimization show an ORC system that reaches high efficiencies, comparable
to those typical of existing system
Adsorção de carotenos de óleo de palma utilizando celulose como adsorvente.
Carotenos são compostos antioxidantes com importante função na manutenção da saúde humana. O óleo de palma é uma importante fonte natural de carotenos, sendo os isômeros α‑ caroteno e β‑caroteno presentes majoritariamente. O processo industrial de refino desse óleo leva à destruição dos carotenos durante o branqueamento com terras diatomáceas (que também podem favorecer a oxidação) e durante a etapa de desodorização. Diferentes tipos de celulose que passaram por pré‑tratamento com gordura refinada de palma se mostraram um material promissor e alternativo à s terras diatomáceas. Por outro lado, as celuloses puras, nas condições estudadas, não foram capazes de concentrar quantidade significativa de carotenos. Considerando α‑celulose, celulose microfibrilada e celulose nanocristalina com pré‑tratamento, essa última apresentou maior potencial em adsorver os carotenos do óleo de palma
Phenomenlogical and predictive studies of confinement and global heating in JET neutral beam heated limiter plasmas
Spectroscopic measurement of impurity transport coefficients and penetration efficiencies in Alcator C-Mod plasmas
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