In this study, the effect of surface roughness on convective heat transfer in two-dimensional parallel plate microchannels is analyzed numerically for steady-state, single-phase, developing, and laminar air flow in the slip flow regime. Slip velocity and temperature jump at wall boundaries are imposed to observe the rarefaction effect. The effect of triangular roughness elements on Nusselt number are compared to cases with smooth surfaces. The results indicate that increasing surface roughness reduces heat transfer in continuum. However, in slip flow regime, an increase in the Nusselt number with increasing roughness height is observed; this increase being more pronounced at low rarefied flows. It is also found that the presence of axial conduction and viscous dissipation have increasing effects on heat transfer in smooth and rough channels, compared to cases where they are neglected.


Gumgum, S.; Tezer, Münevver (Informa UK Limited, 2010-01-01)
The main purpose of this article is to present the use of the dual reciprocity boundary element method (DRBEM) in the analysis of the unsteady natural convective flow of micropolar fluids in a differentially heated rectangular cavity. The finite-difference method (FDM) is used for time discretization. All the convective terms and vorticity boundary condition are evaluated in terms of DRBEM coordinate matrix. Solutions are obtained for several values of microstructure parameter (k), Rayleigh number (Ra), and...
Effect of surface roughness in microchannels on heat transfer
Turgay, Metin Bilgehan; Güvenç Yazıcıoğlu, Almıla; Department of Mechanical Engineering (2008)
In this study, effect of surface roughness on convective heat transfer and fluid flow in two dimensional parallel plate microchannels is analyzed by numerically. For this purpose, single-phase, developing, laminar fluid flow at steady state and in the slip flow regime is considered. The continuity, momentum, and energy equations for Newtonian fluids are solved numerically for constant wall temperature boundary condition. Slip velocity and temperature jump at wall boundaries are imposed to observe the rarefa...
Mathematical expression of the temperature profile and experimental determination of compression heating of ethylene glycol during high hydrostatic pressure processing
Buzrul, S.; Alpas, Hami; Largeteau, A.; Demazeau, G. (Informa UK Limited, 2007-03-01)
In this study, we aimed to describe the temperature profile in the pressure vessel and the compression heating during high hydrostatic pressure (HHP) processing. Regression coefficients (R-2), root mean square error (RMSE) values and residual plots suggested that fourth-order polynomial function produced reasonable fits to define the temperature profile for all the pressures studied (300-600 MPa). If all the coefficients of this empirical model are determined, initial and final temperatures, a value close t...
Influence of mutual drag of the carrier-phonon system on the thermopower and transverse Nernst-Ettingshausen effect
Babaev, MM; Gassym, TM; Tas, M; Tomak, Mehmet (American Physical Society (APS), 2003-03-15)
The thermopower and Nernst-Ettingshausen (NE) effect in degenerate semiconductors and semimetals placed in high electric and magnetic fields are calculated by taking into account the heating of both electrons and phonons as well as their thermal and mutual drags. The magnetic and electric field dependences of the thermoelectric power and the transverse NE voltage are found in analytical forms. It is shown that in weak and high transverse magnetic fields, the electronic and phonon parts of the NE coefficient...
Study of trapping and recombination centres in Tl2InGaTe4 chain crystals by dark electrical conductivity and photoconductivity measurements
QASRAWI, ATEF FAYEZ HASAN; Hasanlı, Nızamı (Informa UK Limited, 2007-01-01)
Dark electrical conductivity and photoconductivity of Tl2InGaTe4 single crystals have been measured and analyzed in the temperature region 100-300 K. The dark electrical conductivity measurements revealed an intrinsic- or extrinsic-type of conductivity above or below 210 K, respectively. From intrinsic conductivity data analysis, the energy band gap of Tl2InGaTe4 crystals was determined as 0.85 eV. In the extrinsic region, the dark conductivity arises from a donor energy level located at 0.30 eV below the c...
Citation Formats
M. B. Turgay and A. Güvenç Yazıcıoğlu, “EFFECT OF SURFACE ROUGHNESS IN PARALLEL-PLATE MICROCHANNELS ON HEAT TRANSFER,” NUMERICAL HEAT TRANSFER PART A-APPLICATIONS, pp. 497–514, 2009, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/49308.