@TechReport{BortoliFoCrisFach:2019:MoCaLa,
author = "Bortoli Filho, Jaime and Cristaldo, Cesar Flaubiano da Cruz and
Fachini Filho, Fernando",
title = "Efeito da concentra{\c{c}}{\~a}o de nanopart{\'{\i}}culas na
vaporiza{\c{c}}{\~a}o de gotas de ferrofluido e nanofluido:
modelo para um calor latente efetivo",
institution = "Instituto Nacional de Pesquisas Espaciais",
year = "2019",
type = "RPQ",
address = "S{\~a}o Jos{\'e} dos Campos",
note = "{Bolsa PIBIC/INPE/CNPq}",
keywords = "Aquecimento Magn{\'e}tico. Combust{\~a}o de gotas. Ferrofluidos,
Heat. Droplet Combustion. Ferrofluids.",
abstract = "Neste trabalho {\'e} avaliado o aquecimento, a
vaporiza{\c{c}}{\~a}o e combust{\~a}o de uma gota de ferrouido
(l{\'{\i}}quido com nanopart{\'{\i}}culas dispersadas) sob
inu{\^e}ncia de um campo magn{\'e}tico externo alternado. Em
resposta ao campo magn{\'e}tico, a movimenta{\c{c}}{\~a}o das
part{\'{\i}}culas promove uma gera{\c{c}}{\~a}o calor no
interior da gota devido {\`a} relaxa{\c{c}}{\~a}o
magn{\'e}tica, que opera como fonte de calor. A
gera{\c{c}}{\~a}o de calor ocorre devido ao atrito
(dissipa{\c{c}}{\~a}o viscosa) entre as nanopart{\'{\i}}culas
e o fluido adjacente a elas. Este movimento {\'e} ocasionado
devido a rota{\c{c}}{\~a}o das part{\'{\i}}culas em resposta
{\`a} altern{\^a}ncia do campo, que promove o alinhando e
desalinhamento do dipolo das part{\'{\i}}culas, este movimento
ocorre de maneira c{\'{\i}}clica respondendo {\`a}s
propriedades do campo magn{\'e}tico. Desta forma, a presente
an{\'a}lise considera dois mecanismos (fluxo de calor do ambiente
externo e aquecimento magn{\'e}tico) fornecendo calor
simultaneamente para o aquecimento e vaporiza{\c{c}}{\~a}o da
gota. Esta an{\'a}lise considera um campo magn{\'e}tico de alta
pot{\^e}ncia e uma distribui{\c{c}}{\~a}o uniforme das
part{\'{\i}}culas, com isso, o interior da gota {\'e}
homogeneamente aquecido. Contudo, ocorre a forma{\c{c}}{\~a}o de
uma camada limite t{\'e}rmica na interface entre as fases
l{\'{\i}}quida e gasosa. Para a an{\'a}lise dos efeitos no
interior da camada limite uma reescala{\c{c}}{\~a}o {\'e}
realizada nas coordenadas espaciais e temporais. No presente
modelo, a gota {\'e} aquecida at{\'e} sua temperatura de
ebuli{\c{c}}{\~a}o de maneira muito r{\'a}pida. Al{\'e}m
disso, sob certas condic{\~o}es, a temperatura dentro da camada
limite t{\'e}rmica torna-se maior que a temperatura na
superf{\'{\i}}cie, o que leva a gota a atingir a temperatura de
ebuli{\c{c}}{\~a}o em uma regi{\~a}o no interior da gota e
n{\~a}o na superf{\'{\i}}cie. A diferen{\c{c}}a de temperatura
entre a camada limite t{\'e}rmica e a superf{\'{\i}}cie,
ocasiona um uxo de calor extra para a superf{\'{\i}}cie,
resultando num aumento na taxa de vaporiza{\c{c}}{\~a}o.
ABSTRACT: The present work aims to evaluate the heating,
vaporization and combustion of a droplet of ferrofluid (liquid
with dispersed nanoparticles) under the influence of an
alternating external magnetic field. In response to the magnetic
field, particle movement promotes heat generation within the
droplet due to magnetic relaxation, which operates as a heat
source. Heat generation occurs due to friction (viscous
dissipation) between the nanoparticles and the fluid adjacent to
them. This movement is caused due to the rotation of the particles
in response to the field alternation, which promotes the alignment
and misalignment of the particle dipole, this movement occurs in a
cyclic manner responding to the magnetic field properties. Thus,
the present analysis considers two mechanisms (external
environment heat flux and magnetic heating) providing heat
simultaneously for heating and vaporization of the droplet. This
analysis considers a high power magnetic field and even particle
distribution, so the inside of the droplet is homogeneously
heated. However, a thermal boundary layer forms at the interface
between the liquid and gas phases. For the analysis of the effects
inside the boundary layer a rescaling is performed in the spatial
and temporal coordinates. In the present model, the droplet is
heated to its boiling temperature very quickly. In addition, under
certain conditions, the temperature within the thermal boundary
layer becomes higher than the surface temperature, which causes
the drop to reach boiling temperature in a region within the drop
rather than on the surface. The temperature difference between the
thermal boundary layer and the surface causes an extra heat flux
to the surface, resulting in an increase in vaporization rate.",
affiliation = "{Universidade Federal do Pampa (UNIPAMPA)} and {Universidade
Federal do Pampa (UNIPAMPA)} and {Instituto Nacional de Pesquisas
Espaciais (INPE)}",
language = "pt",
pages = "25",
ibi = "8JMKD3MGP3W34R/3U33ED2",
url = "http://urlib.net/ibi/8JMKD3MGP3W34R/3U33ED2",
targetfile = "JAIME BARTOLI.pdf",
urlaccessdate = "27 abr. 2024"
}