11 research outputs found
Microstructured reactor as a pre-turbo catalytic converter
The idea of a structured catalytic converter
placed immediately after engine exhaust valves, thus
operating on high gas temperature and velocity, is
explored. The assumption is that major part of the reactor
operates in the entry region where Nusselt and Sherwood
numbers are highly enhanced. In this work, flow resistances
as well as heat and mass transfer coefficients were studied
for gas velocities exceeding 50 m/s. Consequently, the
transition range (between laminar and turbulent flows) was
reached. The comparison with classic monolith has shown
significant improvement in heat or mass transfer paid by
slight increase in flow resistance
Analogia transportu ciep艂a i masy : dyskusja problemu
The study deals with the heat and mass transfer analogy developed for both laminar and turbulent flows. The Chilton-Colburn and L茅veque analogies are discussed. The Fourier-Kirchhoff equations covering the heat and mass transport as well as their theoretical solutions are also described. The ratio of Schmidt-to-Prandtl number for gases and liquids, obtained using the film and the penetration models, are discussed.Praca po艣wi臋cona jest tematyce analogii transportu ciep艂a i masy dla przep艂ywu laminarnego i turbulentnego. Omowiono analogie Chiltona-Colburna oraz Leveque'a. Opisano tak偶e rownania Fouriera-Kirchhoffa dla transportu ciep艂a i masy oraz ich teoretyczne rozwi膮zania. Przedstawiono stosunek liczby Schmidta do Prandtla dla gazow i cieczy uzyskany przy zastosowaniu modeli filmu i penetracji
Flow resistance, heat and mass transfer for triangular short-channel structures. Experiments
Tr贸jk膮tne struktury kr贸tkokana艂owe s膮 bardzo kr贸tkimi monolitami o kszta艂cie przekroju poprzecznego kana艂u zbli偶onym do tr贸jk膮ta r贸wnobocznego. D艂ugo艣膰 kana艂u struktury jest na tyle kr贸tka, 偶e w przewa偶aj膮cej jego cz臋艣ci, wyst臋puje rozwijaj膮cy si臋 przep艂yw laminarny. Zjawisko to powoduje znaczny wzrost wsp贸艂czynnik贸w wnikania ciep艂a i masy, ale te偶 wzrost opor贸w przep艂ywu w por贸wnaniu z klasycznymi monolitami o d艂ugich kana艂ach. Podczas pomiar贸w wnikania ciep艂a struktury kr贸tkokana艂owe by艂y ogrzewane p艂yn膮cym przez nie pr膮dem elektrycznym. W celu uzyskania rozwi膮zania dla transportu masy zastosowano analogi臋 transportu ciep艂a i masy dla przep艂ywu laminarnego. Opory przep艂ywu mierzono przy pomocy mikromanometru Recknagla i miernika elektronicznego. Wyniki otrzymane dla struktur tr贸jk膮tnych por贸wnano z najcz臋艣ciej u偶ywanymi monolitami ceramicznymi i z艂o偶em ziaren usypanych.Triangular short-channel structures are very short monoliths of triangular cross-sectional channel shape. The length of the channel structure is so short, that for the most part of the channel, the developing laminar flow occurs. This phenomenon leads to highly enhanced heat and mass transfer, but the flow resistance is increased as well compared with classic long channel monoliths. During the heat transfer experiments the structures were heated by strong electric current flowing directly through them. The heat transfer experimental results were transformed to the mass transfer representation using heat and mass transfer analogy for the laminar flow. The flow resistance was measured using the Recknagel micromanometer and electronic indicator. The results obtained for the triangular structures were compared with the commonly used ceramic monolith and packed bed