The authors gratefully acknowledge funding support from the Ministry of Science and Technology, MOST (project numbers: MOST 104-2218-E-002 -004, MOST 105-2218-E-002-019, MOST 105-2221-E-002 -107 -MY3, MOST 102-2221-E-002 -133 -MY3, and MOST 102-2221-E-002 -088 -MY3).

1. Preparação das superfícies modificadas <ol><li> Polir manualmente a peça de teste (cilindro oco de cobre com um comprimento de 40 mm (l), um diâmetro exterior de 25 mm (d o), e um diâmetro interno de 18 mm (d i)) durante 15 min, utilizando um # 2000 esmeril papel. Limpar a superfície polida, enxaguando-se com acetona seguida de água DI. </li><li> Colocar a peça de teste polido numa estufa durante 2 h a uma temperatura constante de 120 ° C. </li><li> Prepara-se uma solução super-hidróf ila nanopartícula SiO2 usando os seguintes passos. <ol><li> Preparar a solução A por mistura de 1: 4 proporções molares de tetraetoxisilano e ua DI. Adicionar 2 gotas de HCl concentrado 37% à solução A e agitou-se durante 2 h. </li><li> Adicione a soluo B por mistura de uma razão de 1: 3 molar de etanol e de água Dl. </li><li> Misturar 1 ml de solução A a 80 ml de solução B e agita-se durante 2 h. </li><li> Adicionar 32 g de SiO 2 nanopartículas (diâmetro de 40 nm) para a solu preparadoção e mexa por 1 h. </li></ol></li><li> Mergulha-se o pedaço de teste na solução preparada por meio do aparelho de revestimento por imersão com uma velocidade de 5 mm / min. Manter a peça de teste revestidos num forno a 120 ° C durante 1 h. </li><li> Preparar 2, 4, 8 e padrões dos híbridos interlined com diferentes orientações ao longo da direcção axial (como mostrado na Figura 1), utilizando os seguintes passos. <ol><li> Mascarar a área a não ser revestidos usando a fita de isolamento de acordo com o número requerido de entrelinhas com a orientação correcta (para a superfície 2-interlinha em uma orientação de 0 °, ajustar Interlines no centro e a área de super-hidróf ila (área a ser revestida) sobre o lado de cima. por outro lado, para a orientação de 90 °, ajustar uma entrelinha na parte superior e outra na parte inferior e para a orientação de 180 °, ajustar a área de super-hidróf ila, na parte inferior e as entrelinhas no centro. do mesmo modo, ajustar o posição dos 4, 8 superfícies interlined com o diferente órientation como mostrado na Figura 1). </li><li> Mergulha-se o provete mascarado na solução preparada por meio de um aparelho de revestimento por imersão, mergulho a uma velocidade de imersão e de alta origem a uma velocidade lenta de 5 mm / min. Manter a peça de teste revestidos num forno a 120 ° C durante 1 h. </li><li> Remover a fita de isolamento a partir da área mascarada para se obter o número necessário de entrelinhas com a orientação correcta. </li></ol></li></ol><img alt="figura 1" src="/files/ftp_upload/55387/55387fig1.jpg" /> Figura 1. Selecção de várias superfícies interlined. (a) Esquema das várias superfícies interlined com orientações diferentes. A relação de uma superfície de cobre liso e uma superfície super-hidróf ila área é de 1: 1 em todas as condições. critérios de selecção (b) a orientação. (c) vista isométrica de dois interlinha superfície orientada a 0 ° ângulo. Orientação é seleccionado como o ângulo entre a linha de base e de revestimentoA linha central do primeiro padrão hidrófilo do lado de cima e que é medida numa direcção dos ponteiros do relógio. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig1large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a> 2. Procedimento Experimental <ol><li> Usando a fita isolante, fixar um tubo de vidro, em cada base circular da peça de ensaio revestido. </li><li> Horizontalmente fixar este conjunto para a câmara 140- 140- x x 160 mm (como se mostra na Figura 2) usando pasta de silicone de acordo com a posição requerida de entrelinhas. </li><li> Coloque um 550-W, 18 mm de diâmetro, e aquecedor de cartucho 40 mm de comprimento com uma película fina de pasta térmica na área circunferencial no orifício da peça de teste. </li><li> Ligar o aquecedor de cartucho para uma unidade de fonte de alimentação de corrente contínua (DC). </li><li> Lugar do tipo T termopares para os 8 furos de 1 mm igualmente espaçados, com profundidades alternados de 5 milímetros e 7 mm, como mostrado na figura3 Ligue-los para o registrador de dados. </li><li> Inserir e fixar detectores de temperatura de resistência (RTD), um condensador de refluxo, e um aquecedor auxiliar nos espaços proporcionados na tampa superior. Corrigi-los sobre a câmara de ebulição. </li><li> Encha 1400 mL de água Dl para dentro da câmara de ponto de ebulição piscina. </li><li> Ligar o condensador de refluxo a uma câmara de arrefecimento que é mantido a 5 ° C. </li><li> Antes do experimento, ferver vigorosamente a água desionizada na câmara de ponto de ebulição piscina durante 30 min utilizando o aquecedor auxiliar. </li><li> Manter a água Dl no estado de ebulição saturada usando o aquecedor auxiliar. Subsequentemente, ligar a fonte de alimentação e dar uma corrente inicial de 0,1 A. </li><li> Esperar durante 2 minutos, a fim de atingir um estado de equilíbrio. Em seguida, aumentar a corrente elétrica com incrementos de 0,3 A. </li><li> Registar a temperatura em cada entrada de energia usando o registador de dados. Continue a experiência até que uma corrente máxima de 4 A seja alcançado. Enquanto isso, registrar a bolha dinâmica f<html> ou cada entrada de energia utilizando uma câmara CCD colocado em frente da câmara de ebulição de piscina, que é focado sobre a peça de teste. </li></ol><img alt="Figura 2" src="/files/ftp_upload/55387/55387fig2.jpg" /> Figura 2. Esquema da Câmara Pool-fervente. tubos de vidro são ligadas a ambos os lados do cilindro oco de cobre com pasta de silicone. Este é fixo na câmara de ponto de ebulição piscina com pasta de silicone. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig2large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a> <img alt="Figura 3" src="/files/ftp_upload/55387/55387fig3.jpg" /> Figura 3. Termopar Posicionamento. 8 termopares são colocados no interior dos furos de 1 mm de diâmetro de modo circunferencial no lugar peça de ensaio com um diâmetro de 20 mm. As profundidades dos furos de 1 mm de diâmetro alternados são fixas a 5 mm e 7 mm, respectivamente./files/ftp_upload/55387/55387fig3large.jpg&quot; target = &#39;_ blank&#39;&gt; Clique aqui para ver uma versão maior desta figura. 3. Redução de Dados <ol><li> Calcular a entrada de calor (Q) usando a seguinte equação 19 Q = I V (1) NOTA: I e V são a corrente de entrada em amperes e a voltagem em volts, respectivamente. </li><li> Estimar a perda de calor (perda Q) a partir das duas superfícies laterais, usando a fórmula 19: <img alt="equação 2" src="/files/ftp_upload/55387/55387eq2.jpg" /> (2) NOTA: K é a condutividade térmica do cobre; T 7 mm e T 5 milímetros são os valores médios da temperatura a uma profundidade de 7 mm e 5 mm, respectivamente; ? X (2 mm) é a diferença entre as profundidades; e <img alt="equação 2B" src="/files/ftp_upload/55387/55387eq2b.jpg" /> é a área da secção transversal do teste p<html> IECE. </li><li> Determinar o fluxo de calor (q &#39;&#39;), usando a seguinte fórmula 19: <img alt="equação 3" src="/files/ftp_upload/55387/55387eq3.jpg" /> (3) NOTA: A = π d o L representa a área periférica da peça de teste. </li><li> Calcular o sobreaquecimento parede (usando a seguinte equação 19: <img alt="equação 4" src="/files/ftp_upload/55387/55387eq4.jpg" /> (4) NOTA: Tm representa a média de T 7 mm e t 5 mm, o comprimento da peça de ensaio, r o (12,5 mm), o raio externo do corpo de prova, r m (10 mm), o raio do provete no medição de furos, e T é sentou a temperatura de saturação de água DI, como mostrado na Figura 4. </li><li> Calcular o HTC (α) com a seguinte fórmula 19: pload / 55387 / 55387eq5.jpg&quot;/&gt; (5) </li></ol><img alt="Figura 4" src="/files/ftp_upload/55387/55387fig4.jpg" /> Figura 4. Esquema da Análise da temperatura da parede. temperatura da parede é calculada usando a temperatura média medida e conhecida resistência térmica cilíndrica. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig4large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a>

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The authors declare that they have no competing financial interests.

The main goal of this investigation was to develop a pool-boiling heat sink for high heat dissipation applications, such as nuclear reactors, boilers, and heat pipes, by introducing the hybrid wettable surface, as described in the protocol section. These surfaces can produce better pool-boiling performances than homogeneous wettable surfaces (hydrophilic and hydrophobic). The improvement in the boiling heat-transfer performance is due to an increase in active nucleation sites and the easy detachment of the formed bubbles...

Um sistema de alta calor de fluxo-sustentada proporcionando arrefecimento na gama de 10-10 maio W / cm2 é necessária nos campos emergentes da electrónica, defesa, aviónica, e desenvolvimento de dispositivo nuclear. de arrefecimento convencional com ar é insuficiente para estas aplicações, devido ao coeficiente de transferência de calor baixo (HTC) para ambas as condições Free- e de convecção forçada. As técnicas de arrefecimento à base de mudança de fase, tais como piscina de ebulição e fluxo de ebulição, são suficientemente boas para remover fluxos de calor elevadas da ordem de 10 - 1000 W / cm 2 1. Uma vez que o processo de transferência de calor de duas fases é isotérmica, a temperatura do dispositivo arrefecida é quase constante ao longo da sua superfície. Devido à variação insignificante da temperatura ao longo da superfície, o choque térmico do dispositivo pode ser eliminado. No entanto, a principal limitação em ebulição parâmetro de transferência de calor é o fluxo crítico de calor (ICC), o que provoca um aumento anormal da temperatura dois </sup&gt;. Nas últimas décadas, uma extensa pesquisa foi realizada para melhorar a CHF usando modificação da superfície, nanofluidos, e revestimentos de superfície 3, 4, 5, 6, 7, 8, 9, 10, 11. Entre os vários métodos, revestimentos de superfície são encontrados para ser o melhor método para melhorar a CHF devido ao aumento substancial na área de superfície. Os revestimentos superficiais geralmente aumentar a transferência de calor por acção da aleta, efeitos de porosidade, e molhabilidade da superfície 12. molhabilidade da superfície desempenha um papel significativo na fervura de transferência de calor. Estudos anteriores mostram que, em condições de calor de fluxo mais baixas, a superfície hidrofóbica mostra melhor HTC devido ao início de nucleação. No entanto, amaior fluxo de calor, o desprendimento das bolhas formadas é lento devido à baixa afinidade de água em direcção à superfície. Isto leva a bolha coalescência e resulta numa menor 3 CHF. Por outro lado, uma superfície hidrofílica produz um CHF mais elevado, por causa do rápido desprendimento das bolhas formadas, mas dá uma HTC inferior a fluxos de calor de baixo, devido ao atraso na bolha 13 de nucleação. As estruturas híbridas mostram uma melhoria notável em ebulição de transferência de calor para todos os fluxos de calor devido ao efeito combinado de hidrofobicidade e hidrofilicidade 14, 15, 16. Hsu et al. produzido superfície molhável heterogénea por revestimento super-hidróf ila Si nanopartículas sobre uma superfície de cobre mascarado. Conseguiram diferentes rácios de molhabilidade, variando o tempo de revestimento. O início da ebulição ocorreu mais cedo nas superfícies heterogéneos em comparação com o homogeneous superfície, o que reduziu substancialmente a parede 17 sobreaquecer. Jo et al. realizados estudos de transferência de calor de ebulição nucleada em superfícies de molhagem hidrofílicas, hidrofóbicas, e heterogéneas. A superfície molhante heterogénea foi composta por pontos estampados hidrofóbicas na superfície hidrofílica. Eles tem HTCs mais elevados e ao mesmo CHF para a superfície heterogénea, em comparação com a superfície hidrofílica. Uma melhoria na fervura de transferência de calor depende diretamente do número de pontos na superfície e sobre as condições de ebulição 18. Neste estudo, os padrões molháveis ​​híbridos axiais foram produzidas sobre uma superfície de cobre cilíndrica utilizando a técnica de revestimento por imersão. -Pool ebulição estudos de transferência de calor foram conduzidos para determinar os efeitos do número de entrelinhas e da orientação do padrão molhável híbrido. Ebulição do fluxo de calor, HTC, e dinâmicas de bolha foram analisadas para todos os substratos revestidos e nósre em comparação com o substrato de cobre.

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			<td height="22" style="height:22px;width:201px;">Thermal paste</td>
			<td style="width:279px;">Electrolube</td>
			<td style="width:203px;">EG-30&#160;</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:201px;">Insulation Tape</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;">Kapton Tape</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Sandpaper</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;">#2000</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:201px;">Heating furnace</td>
			<td style="width:279px;">Chung Chuan</td>
			<td style="width:203px;">Hong Sen HS-101</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:201px;">Electronic scales</td>
			<td style="width:279px;">A&#38;D co. Ltd</td>
			<td style="width:203px;">GX400</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Ultrasonic cleaner</td>
			<td style="width:279px;">Bransonic</td>
			<td style="width:203px;">Bransonic 3510</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Magnet stirrer</td>
			<td style="width:279px;">Yellow line</td>
			<td style="width:203px;">MST D S1</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Data logger&#160;</td>
			<td style="width:279px;">Yokogawa</td>
			<td style="width:203px;">MX-100</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">CCD camera</td>
			<td style="width:279px;">JVC</td>
			<td style="width:203px;">LY35862-001A</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Silicon paste</td>
			<td style="width:279px;">Permatex</td>
			<td style="width:203px;">599BR</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Power supply</td>
			<td style="width:279px;">Gwinstek</td>
			<td style="width:203px;">GPR-20H50D</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Teflon tape&#160;</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;">CS170000</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Contact Angle Goniometer</td>
			<td style="width:279px;">Sindatek</td>
			<td style="width:203px;">Model 100SB</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:201px;">Auxiliary Heater</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">T- type thermocouples</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Reflux Condenser&#160;</td>
			<td style="width:279px;">Chuan Chi Trading Co. Ltd</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:201px;">Fiber glass</td>
			<td style="width:279px;">Professional Plastics, Taiwan</td>
			<td style="width:203px;"></td>
			<td style="width:115px;"></td>
		</tr>
	</tbody>
</table>

pool-boiling heat-transfer enhancement on cylindrical surfaces with hybrid wettable patterns

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the hybrid wettable pattern. Hybrid wettable patterns were produced by coating superhydrophilic SiO2 on a masked, hydrophobic, cylindrical copper surface. Using de-ionized (DI) water as the working fluid, pool-boiling heat-transfer studies were conducted on the different surface-treated copper cylinders of a 25-mm diameter and a 40-mm length. The experimental results showed that the number of interlines and the orientation of the hybrid wettable pattern influenced the wall superheat and the HTC. By increasing the number of interlines, the HTC was enhanced when compared to the plain surface. Images obtained from the charge-coupled device (CCD) camera indicated that more bubbles formed on the interlines as compared to other parts. The hybrid wettable pattern with the lowermost section being hydrophobic gave the best heat-transfer coefficient (HTC). The experimental results indicated that the bubble dynamics of the surface is an important factor that determines the nucleate boiling.

Experiências de transferência de calor de ponto de ebulição de piscina foram realizados sobre uma superfície cilíndrica molhável híbrido utilizando a disposição experimental cujo esquema está ilustrado na Figura 5. O procedimento experimental de ponto de ebulição piscina explicado no passo 2 da secção protocolo foi realizado com sucesso, para investigar o efeito do número de entrelinhas e da orientação do padrão molhável híbrido no desempenho de pont...

Watch this Scientific Journal Video about Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns at JoVE.com

Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns

experiências de transferência de calor em ebulição piscina foram realizados para observar os efeitos de padrões molháveis ​​híbridos sobre o coeficiente de transferência de calor (HTC). Os parâmetros de investigação são o número de entrelinhas e a orientação do padrão de superfície molhável modificado.

Enhancement Pool-ebulição de transferência de calor em cilíndricos Superfícies com padrões molháveis ​​híbridos

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the ...

pool-boiling-heat-transfer-enhancement-on-cylindrical-surfaces-with

Research

JoVE Journal

Engineering

8.9K visualizações.  National Taiwan University.  experiências de transferência de calor em ebulição piscina foram realizados para observar os efeitos de padrões molháveis ​​híbridos sobre o coeficiente de transferência de calor (HTC). Os parâmetros de investigação são o número de entrelinhas e a orientação do padrão de superfície molhável modificado. 

Vídeo: Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns

Micropunching Lithography for Generating Micro- and Submicron-patterns on Polymer Substrates

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of low weight, easy tailoring of properties and a wide spectrum of applications2,3. Due to sensitivity of conducting polymers to environmental conditions (e.g., air, oxygen, moisture, high temperature and chemical solutions), lithographic techniques present significant technical challenges when working with these materials4. For example, current photolithographic methods, such as ultra-violet (UV), are unsuitable for patterning the conducting polymers due to the involvement of wet and/or dry etching processes in these methods. In addition, current micro/nanosystems mainly have a planar form5,6. One layer of structures is built on the top surfaces of another layer of fabricated features. Multiple layers of these structures are stacked together to form numerous devices on a common substrate. The sidewall surfaces of the microstructures have not been used in constructing devices. On the other hand, sidewall patterns could be used, for example, to build 3-D circuits, modify fluidic channels and direct horizontal growth of nanowires and nanotubes.
A macropunching method has been applied in the manufacturing industry to create macropatterns in a sheet metal for over a hundred years. Motivated by this approach, we have developed a micropunching lithography method (MPL) to overcome the obstacles of patterning conducting polymers and generating sidewall patterns. Like the macropunching method, the MPL also includes two operations (Fig. 1): (i) cutting; and (ii) drawing. The "cutting" operation was applied to pattern three conducting polymers4, polypyrrole (PPy), Poly(3,4-ethylenedioxythiophen)-poly(4-styrenesulphonate) (PEDOT) and polyaniline (PANI). It was also employed to create Al microstructures7. The fabricated microstructures of conducting polymers have been used as humidity8, chemical8, and glucose sensors9. Combined microstructures of Al and conducting polymers have been employed to fabricate capacitors and various heterojunctions9,10,11. The "cutting" operation was also applied to generate submicron-patterns, such as 100- and 500-nm-wide PPy lines as well as 100-nm-wide Au wires. The "drawing" operation was employed for two applications: (i) produce Au sidewall patterns on high density polyethylene (HDPE) channels which could be used for building 3D microsystems12,13,14, and (ii) fabricate polydimethylsiloxane (PDMS) micropillars on HDPE substrates to increase the contact angle of the channel15.

A micropunching lithography approach is developed to generate micro- and submicron-patterns on top, sidewall and bottom surfaces of polymer substrates. It overcomes the obstacles of patterning conducting polymers and generating sidewall patterns. This method allows rapid fabrication of multiple features and is free of aggressive chemistry.

Micropunching Litografia de Geração de Micro e submicrométricas-padrões sobre substratos poliméricos

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of ...

Engenharia

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Sondagem e Mapeamento superfície do eletrodo em células a combustível de óxido sólido

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

Fabricação de Nano-engenharia transparentes Óxidos Realização por deposição por laser pulsado

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

High-speed Particle Image Velocimetry Near Surfaces

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The complex nature of these flows may be studied using particle image velocimetry (PIV), a laser-based imaging technique for optically accessible flows. Though many forms of PIV exist that extend the technique beyond the original planar two-component velocity measurement capabilities, the basic PIV system consists of a light source (laser), a camera, tracer particles, and analysis algorithms. The imaging and recording parameters, the light source, and the algorithms are adjusted to optimize the recording for the flow of interest and obtain valid velocity data. 
Common PIV investigations measure two-component velocities in a plane at a few frames per second. However, recent developments in instrumentation have facilitated high-frame rate (&gt; 1 kHz) measurements capable of resolving transient flows with high temporal resolution. Therefore, high-frame rate measurements have enabled investigations on the evolution of the structure and dynamics of highly transient flows. These investigations play a critical role in understanding the fundamental physics of complex flows.
A detailed description for performing high-resolution, high-speed planar PIV to study a transient flow near the surface of a flat plate is presented here. Details for adjusting the parameter constraints such as image and recording properties, the laser sheet properties, and processing algorithms to adapt PIV for any flow of interest are included.

A procedure for studying transient flows near boundaries using high-resolution, high-speed particle image velocimetry (PIV) is described here. PIV is a non-intrusive measurement technique applicable to any optically accessible flow by optimizing several parameter constraints such as the image and recording properties, the laser sheet properties, and analysis algorithms.

Alta velocidade da partícula Velocimetry Imagem perto de superfícies

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The ...

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms.
In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station.

A detailed procedure for surface doping of Silicon interfaces is provided. The ultra-shallow surface doping is demonstrated by using phosphorus containing monolayers and rapid annealing process. The method can be used for doping of macroscopic area surfaces as well as nanostructures.

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra ...

Evanescent Field Based Photoacoustics: Optical Property Evaluation at Surfaces

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. Optical property evaluation of thin films and the surfaces of bulk materials is an important step in understanding new optical material systems and their applications. The method presented can estimate thickness, refractive index, and use absorptive properties of materials for detection. This metrology system uses evanescent field-based photoacoustics (EFPA), a field of research based upon the interaction of an evanescent field with the photoacoustic effect. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. This optical near field allows for the highly accurate estimation of material properties on the same scale as the field itself such as refractive index and film thickness. With the use of EFPA and its sub techniques such as total internal reflection photoacoustic spectroscopy (TIRPAS) and optical tunneling photoacoustic spectroscopy (OTPAS), it is possible to evaluate a material at the nanoscale in a consolidated instrument without the need for many instruments and experiments that may be cost prohibitive.

Here we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. This technique evanescent field-based photoacoustics can be used to create a photoacoustic metrology system to estimate materials&#39; thicknesses, bulk and thin film refractive indices, and explore their optical properties.

Evanescente Campo photoacoustics Baseado: Avaliação da Propriedade óptica a Surfaces

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. ...

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO&#903;, -H2C&#903;, -O&#903;, -CO&#903; radicals. During the degradation process, CO and CO2 were also produced.

Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.

A evolução de sílica Coatings nanopartículas-poliéster em superfícies expostas à luz solar

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, ...

Measurements of Local Instantaneous Convective Heat Transfer in a Pipe - Single and Two-phase Flow

This manuscript provides step by step description of the manufacturing process of a test section designed to measure the local instantaneous heat transfer coefficient as a function of the liquid flow rate in a transparent pipe. With certain amendments, the approach is extended to gas-liquid flows, with a particular emphasis on the effect of a single elongated (Taylor) air bubble on heat transfer enhancement. A non-invasive thermography technique is applied to measure the instantaneous temperature of a thin metal foil heated electrically. The foil is glued to cover a narrow slot cut in the pipe. The thermal inertia of the foil is small enough to detect the variation in the instantaneous foil temperature. The test section can be moved along the pipe and is long enough to cover a considerable part of the growing thermal boundary layer.
At the beginning of each experimental run, a steady state with a constant water flow rate and heat flux to the foil is attained and serves as the reference. The Taylor bubble is then injected into the pipe. The heat transfer coefficient variations due to the passage of a Taylor bubble propagating in a vertical pipe is measured as function of the distance of the measuring point from the bottom of the moving Taylor bubble. Thus, the results represent the local heat transfer coefficients. Multiple independent runs preformed under identical conditions allow accumulating sufficient data to calculate reliable ensemble-averaged results on the transient convective heat transfer. In order to perform this in a frame of reference moving with the bubble, the location of the bubble along the pipe has to be known at all times. Detailed description of measurements of the length and of the translational velocity of the Taylor bubbles by optical probes is presented.

This manuscript describes methods aimed at measuring the local instantaneous convective heat transfer coefficients in a single or two-phase pipe flow. A simple optical method to determine the length and the propagation velocity of an elongated (Taylor) air bubble moving at a constant velocity is also presented.

Medições de transferência de calor convectiva instantânea Local em uma tubulação - fluxo único e duas fases

This manuscript provides step by step description of the manufacturing process of a test section designed to measure the local instantaneous heat transfer ...

Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl dimethyl azlactone) (PGMA-b-PVDMA), are presented. Due to the high reactivity of azlactone groups towards amine, thiol, and hydroxyl groups, PGMA-b-PVDMA surfaces can be modified with secondary molecules to create chemically or biologically functionalized interfaces for a variety of applications. Previous reports of patterned PGMA-b-PVDMA interfaces have used traditional top-down patterning techniques that generate non-uniform films and poorly controlled background chemistries. Here, we describe customized patterning techniques that enable precise deposition of highly uniform PGMA-b-PVDMA films in backgrounds that are chemically inert or that have biomolecule-repellent properties. Importantly, these methods are designed to deposit PGMA-b-PVDMA films in a manner that completely preserves azlactone functionality through each processing step. Patterned films show well-controlled thicknesses that correspond to polymer brushes (~90 nm) or to highly crosslinked structures (~1-10 &#956;m). Brush patterns are generated using either the parylene lift-off or interface directed assembly methods described and are useful for precise modulation of overall chemical surface reactivity by adjusting either the PGMA-b-PVDMA pattern density or the length of the VDMA block. In contrast, the thick, crosslinked PGMA-b-PVDMA patterns are obtained using a customized micro-contact printing technique and offer the benefit of higher loading or capture of secondary material due to higher surface area to volume ratios. Detailed experimental steps, critical film characterizations, and trouble-shooting guides for each fabrication method are discussed.

Surface fabrication methods for patterned deposition of nanometer thick brushes or micron thick, crosslinked films of an azlactone block co-polymer are reported. Critical experimental steps, representative results, and limitations of each method are discussed. These methods are useful for creating functional interfaces with tailored physical features and tunable surface reactivity.

Fabricação de superfícies reativas com escova, como filmes de quitosana de polímeros co bloco Azlactone-acrescida e

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl ...

Uncoupling Coriolis Force and Rotating Buoyancy Effects on Full-Field Heat Transfer Properties of a Rotating Channel

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that characterize the transport phenomena in a rotating channel are identified via the parametric analysis of the momentum and energy equations referring to a rotating frame of reference. Based on these dimensionless flow equations, an experimental strategy that links the design of the test module, the experimental program and the data analysis is formulated with the attempt to reveal the isolated Coriolis-force and buoyancy effects on heat transfer performances. The effects of Coriolis force and rotating buoyancy are illustrated using the selective results measured from rotating channels with various geometries. While the Coriolis-force and rotating-buoyancy impacts share several common features among the various rotating channels, the unique heat transfer signatures are found in association with the flow direction, the channel shape and the arrangement of heat transfer enhancement devices. Regardless of the flow configurations of the rotating channels, the presented experimental method enables the development of physically consistent heat transfer correlations that permit the evaluation of isolated and interdependent Coriolis-force and rotating-buoyancy effects on the heat transfer properties of rotating channels.

Here, we present an experimental method for decoupling the interdependent Coriolis-force and rotating-buoyancy effects on full-field heat transfer distributions of a rotating channel.

Força de Coriolis desacopladas e efeitos de flutuabilidade rotativa em campo-total de calor transferir Propriedades de um canal de rotação

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that ...

Enhancement Pool-ebulição de transferência de calor em cilíndricos Superfícies com padrões molháveis ​​híbridos

Enhancement Pool-ebulição de transferência de calor em cilíndricos Superfícies com padrões molháveis híbridos