Heat Transfer: Volume 2最新文献

Arthropod Motion-Sensing Hairs: Biological Models for Micro-Electro-Mechanical Systems 节肢动物运动感应毛发:微机电系统的生物学模型

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1416

J. Humphrey, F. Barth

{"title":"Arthropod Motion-Sensing Hairs: Biological Models for Micro-Electro-Mechanical Systems","authors":"J. Humphrey, F. Barth","doi":"10.1115/imece2000-1416","DOIUrl":"https://doi.org/10.1115/imece2000-1416","url":null,"abstract":"\u0000 The filiform hairs of terrestrial and aquatic arthropods are uniquely sensitive medium motion sensors, refined by natural selection pressures over hundreds of millions of years. These sensors provide biological models for the design and fabrication of corresponding artificial sensors that could be used for fundamental research as well as practical applications. However, the measurement and modeling of filiform hairs poses a highly complex interdisciplinary problem involving various facets of biology, mechanics and mathematics. Specifically, it is of special interest to uncover the basic “design” principles affecting the maximum angular deflection and maximum angular velocity, and their respective resonance frequencies, of the hairs as a function of the physical parameters that affect these four quantities. To this end, the physically-approximate theoretical analysis of Humphrey et al. (2000) is used to predict and understand the performance characteristics of single hairs. Calculated results obtained using the approximate analysis compare well with corresponding results from a more exact physical analysis and with previous measurements and calculations, showing that all qualitative aspects of hair behavior are correctly captured by the simplified theory. The theory is then used to explain the dependence of hair motion on the physical parameters that affect it. The findings of this study suggest that an artificial motion-sensing micro-electro-mechanical system (MEMS), patterned along the lines of an array of hairs, could be designed to detect and resolve the temporal and spatial characteristics of unsteady flow structures in the near-wall region of boundary layer flows.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"207 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116361665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Feedback Thermal Control in Microscale Heat Transport 微尺度热传输中的反馈热控制

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1437

D. Tzou, E. Monda

引用次数: 0

Mixed Convection Adjacent to 3-D Backward-Facing Step 3-D后向台阶附近的混合对流

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1408

An Li, B. Armaly

{"title":"Mixed Convection Adjacent to 3-D Backward-Facing Step","authors":"An Li, B. Armaly","doi":"10.1115/imece2000-1408","DOIUrl":"https://doi.org/10.1115/imece2000-1408","url":null,"abstract":"Results from three-dimensional numerical simulation of laminar, buoyancy assisting, mixed convection airflow adjacent to a backward-facing step in a vertical rectangular duct are presented. The Reynolds number, and duct geometry were kept constant at Re = 200, AR = 8, ER = 2, and S = 1 cm. Heat flux at the wall downstream from the step was kept uniform, but its magnitude was varied to cover a Grashof number (Gr) range between 0.0 to 4000. All the other walls in the duct were kept at adiabatic condition. The flow, upstream of the step, is treated as fully developed and isothermal. The relatively small aspect ratio of the channel is selected specifically to focus on the developments of the three-dimensional mixed convection flow in the separated and reattached flow regions downstream from the step. The presented results focus on the effects of increasing the buoyancy force, by increasing the uniform wall heat flux, on the three-dimensional flow and heat transfer characteristics. The flow and thermal fields are symmetric about the duct’s centerline. Vortex generated near the sidewall, is the major contributor to the three dimensional behavior in the flow domain, and that feature increases as the Grashof number increases. Increasing the Grashof number results in an increase in the Nusselt number, the size of the secondary recirculating flow region, the size of the sidewall vortex, and the spanwise flow from the sidewall toward the center of the channel. On the other hand, the size of the primary reattachment region decreases with increasing the Grashof number. That region lifts away and partially detaches from the downstream wall at high Grashof number flow. The maximum Nusselt number occurs near the sidewalls and not at the center of the channel. The effects of the buoyancy force on the distributions of the three-velocity components, temperature, reattachment region, friction coefficient, and Nusselt number are presented, and compared with 2-D results.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133085715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

Design of a High Performance Cryocooler for Propellant Liquefaction and Storage on Mars 用于火星推进剂液化和储存的高性能制冷机的设计

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1444

Lei Zhou, J. Kapat, L. Chow, S. Lei

{"title":"Design of a High Performance Cryocooler for Propellant Liquefaction and Storage on Mars","authors":"Lei Zhou, J. Kapat, L. Chow, S. Lei","doi":"10.1115/imece2000-1444","DOIUrl":"https://doi.org/10.1115/imece2000-1444","url":null,"abstract":"\u0000 Human exploration of space is extending beyond low earth orbit and Moon as NASA is planning a human mission to Mars in 2014. Past studies indicate that In Situ Propellant Production (ISPP) on Mars is a key enabling technology in Mission to Mars. In ISPP, oxygen and methane, which are to be used as cryogenic propellants for any return vehicle from Mars to Earth, are produced on the Martian surface. Once the propellants are produced in gaseous state, they must be liquefied for storage and use in the ascent vehicle. Cryogenic cooling is needed for both liquefaction and storage since the storage temperature, around 90K for oxygen and 112K for methane, are considerably lower than the average temperature on the Martian surface, which is around 220K.\u0000 This paper presents the preliminary design of a single-stage, lightweight and compact, cryocooler based on reverse Brayton cycle with performance comparable to, but more reliable than, a corresponding Stirling cycle. With the application of micro-scale highly-effective recuperative heat exchanger, the estimated COP of the miniature cryocooler can reach 0.2. Thermal cycle parameters that can influence the cycle performance are studied. The two key enabling components, an integrated and micro-fabricated compressor and motor and a micro-fabricated recuperative heat exchanger, are discussed and shown to be possible with modern technology.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131902219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Interplay Between Thermoelectric and Thermionic Effects in Heterostructures 异质结构中热电和热离子效应的相互作用

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1063/1.1499527

T. Zeng, Gang Chen

引用次数: 11

Fluid Mechanics and Biological Interaction in a Tubular Nitrifier Designed for Use in Space 用于太空的管式硝化器的流体力学和生物相互作用

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1420

K. Pickering, E. Ungar, L. Vega, M. Campbell

引用次数: 0

Thermal Performance of a Residential Basement 住宅地下室的热性能

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1427

A. Emery, D. Heerwagen, C. Kippenhan, D. Steele

引用次数: 0

Effect of Surface Roughness on Gaseous Flow Through Microchannels 表面粗糙度对气体通过微通道流动的影响

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1438

S. Turner, Hongwei Sun, M. Faghri, O. Gregory

引用次数: 2

Transient Bubble Formation on a Polysilicon Micro Resister 多晶硅微电阻的瞬态气泡形成

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1434

Jr-Hung Tsai, Liwei Lin

引用次数: 0

High Temperature Microscale Reactor Analysis Using a Counterflow Heat Exchanger Model 用逆流换热器模型分析高温微型反应器

Heat Transfer: Volume 2 Pub Date : 2000-11-05 DOI: 10.1115/imece2000-1436

R. Peterson, J. A. Vanderhoff

{"title":"High Temperature Microscale Reactor Analysis Using a Counterflow Heat Exchanger Model","authors":"R. Peterson, J. A. Vanderhoff","doi":"10.1115/imece2000-1436","DOIUrl":"https://doi.org/10.1115/imece2000-1436","url":null,"abstract":"\u0000 A microscale reactor model, with axial conduction and radiation heat loss, has been developed for predicting the thermal performance of high temperature systems. The model considers: 1.) flow loss due to non-unity effectiveness, 2.) thermal conduction along the axial direction, and 3.) radiation surface loss to the environment. A system of three coupled differential equations were developed where two of the equations modeled the temperature variation in the fluid streams and the third equation gave the temperature of the wall. The wall equation contained a highly non-linear term linked to radiation surface loss. This study is unique in several ways. First, the boundary conditions for the problem modeled a micro reactor attached to a substrate at ambient temperature while the hot end was free to assume a wall temperature half way between the two fluid temperatures. Next, surface radiation was treated explicitly as a heat loss term. At elevated temperatures, the overall thermal performance of the micro reactor was significantly impacted by this loss mechanism. Finally, an implicit method is described capable of solving the non-linear coupled differential equations. The results of the study are presented in the form of normalized total heat loss curves for each of the three loss mechanisms. A scaling study is presented showing what contributions to heat loss are important as the characteristic length scale of the device is reduced. This study demonstrates that both conduction and surface radiation losses are significant in high temperature micro reactors. Furthermore, the heat loss (in normalized form) by radiation is significant for larger scale devices but the ultimate size limits for a micro reactor will be governed by conduction losses through the structure. For high temperature micro reactor technology to be practical, this study demonstrates that devices must be designed with low thermal conductivity materials, high aspect ratio geometries, and low effective surface emissivities.","PeriodicalId":201774,"journal":{"name":"Heat Transfer: Volume 2","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114136130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1