Department of Mechanical Engineering, Azarbaijan Shahid Madani University, Tabriz, Iran b

Transcription

1 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp EXPERIMENTAL INVESTIGATION ON FLOW AND HEAT TRANSFER FOR COOLING FLUSH-MOUNTED RIBBONS IN A CHANNEL Application of an Electroydrodinamics Active Enancement Metod by Amin ALAMI NIA a * and Antonio CAMPO b a Department of Mecanical Engineering, Azarbaijan Said Madani University, Tabriz, Iran b Department of Mecanical Engineering, University of Texas, San Antonio, Tex., USA Original scientific paper DOI: /TSCI A In te present study, te eat transfer enancement of a bundle of flus-mounted ribbons placed on te floor of a rectangular duct was investigated experimentally. Te flus-mounted ribbons act as eat sources and te cooling appens wit air. Te air flow was 2-D, steady, viscous, and incompressible under eiter laminar (500 Re D 2000) and turbulent (2000 Re D 4500) conditions. Te ydrodynamics and eat transfer beavior of te air flow was studied by means of an active metod wit application of corona wind. Te state-of-te-art of tis work revolves around an experimental investigation of an electroydrodynamics active metod and eat transfer enancement from te surfaces of te flus-mounted ribbons. Due to te intricacies of te required experiment, a special apparatus needed to be designed and constructed. Key words: convective eat transfer, duct flow, flus-mounted ribbons, eat transfer enancement, electroydrodynamics, corona wind Introduction Te majority of electronic boards are constructed wit small elements tat generate considerable amount of eat. Cooling of tese electronic boards constitutes an essential part for teir reliable operation and te main cooling systems deal wit a flow of air troug cannels. Nowadays, because of size reduction (i. e., board compaction), te cooling medium as become a vital part of te system. Optimum active cooling systems are preferred approaces for performance evaluation criteria (PEC) of te electronic boards [1, 2]. Te active metod wit application of corona wind is well known owing to its ability to work wit any external sources of energy. Corona is a visible luminous emission caused by te creation of poton and occurs in te vicinity of sarp edges were te intensity of te electric field is ig. An important aspect of corona discarge is te generation of corona wind, wic is a gas flow induced by corona discarge. Tis penomenon is caused by te ionization of gas molecules and formation of electrons tat accelerate in strong electric fields and collide wit neutral molecules, resulting in more ionization. Because te ions are eavier tan electrons, tey accelerate and drag te neigboring gas molecules. Tis action generates a secondary flow, known as corona wind. * Corresponding autor; amin.alam@azaruniv.edu

2 506 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp Te present work examines an active electroydrodynamics (EHD) metod wit application of positive corona wind for te cooling of eat generating flus-mounted ribbons placed at te base of cannel. Tis is a novel cooling approac, and to te autors knowledge, as not been examined earlier. In recent work [3], experimental investigation on te eat transfer enancement of rectangular ribs wit constant eat flux located in te floor of a rectangular cannel as been acieved. In tis study, te beavior of air flow was studied by passive, active, and compound metods. Te comparison of te results for various boundary conditions of problem was fairly agreement. In previous works [4, 5], numerical study on te eat transfer enancement of rectangular ribs wit constant eat flux located in te floor of a 3-D duct flow as been acieved. In tis study, te effects of te arranged oles between te rectangular ribs in cannels ave been reported. Fujisima et al. [6] provided analyzed te flow interaction between te primary flow and te secondary flow in te wire-duct electrostatic precipitator. Tey extended to incorporate te alternately oriented point corona on te wire-plate type electrodes. Oadi et al. [7] used te wire-plate electrodes for forced convection enancement in pipe flow. Tey sowed tat te two-wire electrode design provided a modest iger enancement compared to te single wire electrode design. Wit two electrodes, tey sowed tat for Reynolds numbers up to 10000, it is possible to use tis tecnique for enancement. Kasayapanand and Kiatsiririot [8, 9] investigated te eat transfer enancement wit te EHD tecnique in laminar forced convection inside a wavy cannel wit different wire electrode arrangements. Te electric field is generated by te wire electrodes carged wit DC ig voltage. Te matematical modeling includes te interactions among te electric flow and temperature fields. Te numerical simulation was firstly applied to te rectangular flat cannel and later to wavy cannel. Kasayapanand et al. [10] investigated te effect of te electrode arrangements in a tube bank wit regards to te caracteristic of EHD eat transfer enancement for low Reynolds numbers. Te numerical modeling of te laminar forced convection includes te interactions among te electric field, te flow field, and te temperature field. From te numerical results, tey sowed tat te eat transfer was enanced by te EHD at a low Reynolds number and te sort distance between te wire electrodes and te tube surface. Often times in termal systems, invigorating te eat transfer rate cause deterioration in te momentum transfer. Tis penomenon is called dissimilarity. At first by placing flus mounted ribbons in te floor cannel, local pressure, and momentum bot drop. Terefore, for a specified inlet velocity situation, more pumping power is needed. On te oter and, due to te local effects suc as disturbance and te extending of contact surface, te eat transfer increases. So it is necessary to articulate a convenient similarity between tese two opposing penomena. By using a suitable active metod, secondary flow of corona wind creates in space between flus mounted ribbons and causes disturbances. In te present work, to avoid immoderate canges in te pysical properties of fluid, te temperature differences between te fluid and flus mounted ribbons are constrained by applying a convenient eat flux on te flus mounted ribbons. Experimental investigation In order to generate data of te air flow patterns around te flus-mounted ribbons, a special apparatus was necessary. In designing te test section, te following conditions were taken into consideration:

3 Alami Nia, A., et al.: Experimental Investigation on Flow and Heat Transfer for THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp A fully developed air flow sould be supplied before te flow enters into te test section. Wit regards to te dimensions of te cannel, te dept to eigt ratio is ig. Because te dept effects ave been ignored te cannel is 2-D. Te apparatus is designed to accommodate flow wit low and large values of Reynolds numbers under laminar (500 ReD 2000) and turbulent (2000 ReD 4500) conditions. Te flow is incompressible wit very small Mac numbers, M 0 0.3, tus any interaction effects of ig voltage electric fields on te measurement of temperature are due to te eliminating side effects of applied ig voltage and te accuracy of termocouples. Figures 1 and 2 sow te layout and te potograp of te main experimental apparatus, respectively. By considering te aforementioned conditions for te main experimental section, a special experimental apparatus was designed for te investigation of eat transfer enancements involving flus mounted ribbons to fluid. For tis purpose, a broad rectangular cannel was used. To measure te volume rate of air flow, te orifice meter was used. Te ratio in diameter (orifice to pipe) was adjusted to be= β d= D A special centrifugal fan was used to produce te air flow. To eliminate disturbances, te test section was located on te suction side of te fan. Figure 1. Te scematic of main apparatus Figure 2. Potograps of te main set-up

4 508 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp Te test section was designed to be a cannel wit 40 cm lengt, 4 cm eigt, and 30 cm widt as sown in fig. 3. Before entering te test section flows from a rectangular cannel wit 2 m lengt, te fluid proceeds wit a Figure 3. Potograp and geometry of te test section rectangular flow-straigtened screen wit unit dimension of 8 mm to 20 mm. Te velocity domain in te test section was 0.11 u 1 m/s. Te ydraulic diameter of te main cannel (especially te test section) was 7.06 cm. Te fan was adjusted to operate wit constant rotation. Te flow rate was measured by te orifice meter under te France standard NF X Te pressure measurements sould be determined wit ig accuracy in te two sides of te orifice. To comply wit tis, a U-type manometer wit kerosene (S. G. = 0.865) was used. In te test section, te ribs were electrically eated wit constant eat flux. To isolate te part attaced to te floor of te cannel, a fire proof fiber was used. Te fire proof fiber is an adequate insulator of eat and electricity. Te flus mounted ribbons were produced using silicon iron foil. Tree flus mounted ribbons were attaced on te floor of te cannel. 2 Te series were connected as resistance to provide a constant eat flux of q w = 4500 W/m by means of a differential voltage transformer. Te flus mounted ribbons ad 3 cm in widt, 30 cm in lengt, and 3 cm in axial spacing between tem. Nine termocouples were used for measuring te temperature of te bottom cannel wall and te ribbons surface in central direction of flow. Te type of termocouples is T-type wit Cu-Constantan (C/C T ). Te geometric layout of termocouples in te test section is sown in fig. 4 and tab. 1, were x denotes te streamwise direction from te position of te first termocouple in te test section. Te x location of te termocouples is determined in te best location for measuring te temperature. Te position of termocouples (x location of termocouples) is increased on surfaces of te ribs. Tis position starts from te first flus mounted to termocouple number 9. Te termocouple number 1 is used for measuring te ambient air temperature. Figure 4. Te termocouples arrangement Table 1. Position of te inserted termocouples No. X [cm] For temperature processing, te ADAM digital system was used. Tis system contains four boards for temperature measurement and a transformation board. Eac measuring board receives te information of termocouples and ten transfers tem to te PC for processing. Hig voltage is applied using a ig voltage supplier for te EHD wire-plate active metod. Various arrangements of wire and plates were made as ground electrodes were designed between te spacing of te flus mounted ribbons. Te ig voltage supplier generated voltages up to

5 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp kv between te wire and ground electrodes. Te corona penomenon was generated between electrodes wit very weak current intensity. Te micro-ammeter is used for current intensity measurements wit a domain of μa and accuracy of 10 μa. In all experimental tests, te polarity of wire electrodes is positive. Te diameter of wire electrodes is 0.6 mm. Te wire and ground electrodes are made from copper and aluminum, respectively. Te primary objective of te present work is te comparison of plain case 1 wit EHD active eat transfer enancement metod. Te geometry of te two cases is sown in figs. 5(a) and (b). Figure 5. Te geometry of two cases, (a) and (b) Te arrangement of electrodes wit teir geometric coding values is illustrated in fig. 6. Te arrangements of electrodes for active metod are displayed in te case 2. Te wire and ground electrodes were inserted between flus mounted ribbons to enancement of eat transfer by means of te secondary flow produced from corona wind of EHD wire-plate actuator. Figure 6. Arrangements of wire electrodes

6 510 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp According to experimental results in active enancement metod, te suitable arrangements of wire electrodes to te ground are arrangements 1 and 3. In active metod, te secondary flow of corona wind is from te cold main flow to te ot zone. In conclusion, two kinds of enancement metods could be beneficial for enancing of eat transfer from flus mounted ribbons. Te aim of tis study is to investigate te eat transfer enancement of 2-D traverse flus-mounted ribbons placed at te base of te cannel. Tree parameters caracterize te laminar air flow wit eat transfer: Rate of eat transfer enancement, E t wit = qrib TW Tref /. Consumed power ratio, E lost and PEC, η e ( TW Tref ) s Et = = ( T T ) s E lost W s ref (1) P = (2) P t e (PEC) E η = (3) E In te sequence of eqs. (1)-(3), q rib is te constant eat flux from flus mounted ribbons to fluid flow, te local eat transfer coefficient, T ref te reference temperature (inlet temperature to te test section), T W te wall temperature in floor of test section, including surface of flus mounted ribbons and spacing of tem, ΔP te pressure loss, and subscript s denotes te plain case witout enancement intervention. Te Re D is Reynolds number based on te ydraulic diameter of te cannel, N EHD te EHD number and it is defined: N lost 2 2 ρe 0 0 i EHD 2 ρfvf vf vf E L be L ul = = = (4) Tis parameter is similar to te ReD based on velocity of electric ions u i and wit te assumption of similar density for ions and neutral fluid particles. In eq. (4), ρ e is te density of electric carge, ρ f te density of fluid, E 0 te electric field, b te mobility of ions, and ν f te kinematics viscosity of fluid and ten u i is defined: I0 ui = (5) q In tis equation, I 0 is te electric current of corona wind, q e0 te electric carge of one electron, wic is C. Te L is te caracteristic lengt and defined [11]: e0 C ln r eff L= D α H r were α is te view angle between wire and ground electrodes (α = 1 for te case of one wire electrode between two ground electrodes and α = 0.5 for te case of one wire and one ground (6)

7 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp electrode). Te C/H is te ratio of space of wire and ground electrodes to cannel eigt. Te r eff /r is te ratio of effective radius of wire and ground electrodes to te radius of wire electrode and r eff is defined as r eff = 4C/π were C is te distance between wire and ground electrodes. By using te active metod of EHD wire-plate actuator, te corona wind as a secondary flow between flus mounted ribbons is created. For analyzing tis penomenon, te new parameter of interaction of secondary flow to te main flow (strengt of EHD), I EHD is introduced: NEHD I EHD = (7) 2 Re Note tat I EHD is an important parameter for te kind of active enancement metod under study ere. Figure 7. Wall temperature distribution in direction of ribbon s surface for forced convection and arrangement 1 (20 kv, Re = 500) Results and discussion Te geometry of flus-mounted ribbons arrangements as illustrated in fig. 5 are: L 1 = L 2 = 110 mm, L = 30 mm, S = 30 mm, H = 40 mm. As it is seen in fig. 7, te distribution of wall temperature for te two cases of plain (witout EHD, ReD = 500) and active cases (arrangement 1; 20 kv) is sown. Te flus-mounted ribbons are eated wit constant eat flux and terefore for comparison of EHD active metod, te plain case (witout EHD, ReD = 500) for confined case is base. In tis figure, te effects of EHD active metod on eat transfer enancement and te temperature reduction are sown in test section. In te space between te flus-mounted ribbons, te insulator (incombustible fiber) as been applied and adiabatic boundary condition brings a temperature reduction. Wit regards to te temperature differences in fig. 7, te percent of eat transfer enancement is of te order of 113%. In fig. 8, te rate of eat transfer enancement for laminar forced convection (ReD = 500) in arrangements 1 and 2 wit voltages of 20 kv and 25 kv is sown. Te effect of voltage on eat transfer enancement depending on te wire arrangement was sown in te figure. In reference to tis figure, te local and average eat transfer enancement as been increased as a consequence of increments in voltage. Te density of electric carge around of wire electrode in arrangement 1 is iger tan tat in arrangement 2. Terefore, arrangement 1 is better tan arrangement 2. D Figure 8. Comparison of rate of eat transfer enancement in direction of ribbon s surface for forced convection and arrangements 1 and 2 (20 and 25 kv, Re = 500) D

8 512 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp Figure 9 displays te rate of eat transfer enancement for laminar forced convection (ReD = 4500) in arrangements 3 and 4 wit voltages of 20 kv and 25 kv. Te effect of voltage on eat transfer enancement depends on te wire arrangement as sown in te figure. It is clear from te figure, tat te local and average eat transfer enancement was increased wit increments in voltage. Terefore, te arrangement 3 is better tan arrangement 4. As it is seen in fig. 10, te rate of eat transfer enancement for laminar-to-turbulent Figure 9. Comparison of rate of eat transfer forced convection in arrangements 1 and 2 wit enancement in direction of ribbon s surface Re = 500 and 3000 is depicted in 20 kv. Te for forced convection and arrangements 3 and 4 (20 and 25 kv, impact of Reynolds number on te eat transfer Re D = 4500) enancement was seen in te figure. Herein, te local and average eat transfer enancement for ReD = 500 is iger tan teir counterparts for ReD = For ig Reynolds numbers, te main flow power is iger tan te power of corona wind (secondary flow) in te main flow eliminating te effects of corona wind. Figure 11 contains te average rate of eat transfer enancement for forced convection in various Reynolds numbers wit arrangement 1 for 20, 25 kv, and 30 kv. Te effect of Reynolds number on average eat transfer enancement was palpable in te figure. In numbers, te Figure 10. Te rate of eat transfer enancement in direction of ribbon s surface average eat transfer enancement in for forced convection and arrangements 1 and 2 ReD = 500 is iger tan tose for oter Reynolds numbers. Te power of corona wind in te (20 kv, Re D = 500 and 3000) case of low Reynolds numbers is iger tan in te case of ig Reynolds numbers. Consequently, te corona wind in low Reynolds numbers affects te main flow better tan in situations of ig Reynolds numbers. Inspection of te figure reveals tat te average eat transfer enancement as been increased wit elevations in voltage. At ig voltages, te density of electric carge and te electric field around of wire electrodes is ig. Tis is interpreted in terms of Figure 11. Te average rate of eat transfer te corona wind, wic at ig voltages as a enancement in various Reynolds numbers wit direct influence on te main flow better tan arrangement 1 for 20, 25, and 30 kv tose situations of low voltages. In figs. 12 and 13, te variations of η e wit I EHD number for active metod of eat transfer enancement in ReD = 500, 2000, and 3000 are presented. As seen in figures, te effect of Reynolds number on eat transfer enancement for active metod demonstrates te

9 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp Figure 12. Te PEC in direction of ribbon s surface for active case in Re D = 500 wit arrangements 1 and 2 Figure 13. Te PEC in direction of ribbon s surface for active case in Re D = 2000 and 3000 wit arrangements 1 and 2 opposite beavior for bot low and ig values. For te active metod, te secondary flow can move furter to te spacing between flus-mounted ribbons. Te pair of figs. 12 and 13, attests tat te density of electric carge around of wire electrode in arrangement 1 is iger tan tat in arrangement 2. As a consequence, arrangement 1 is better tan arrangement 2. Switcing attention to fig. 13 related to ReD = 3000, it is detected tat for positive interaction of te average eat transfer enance- ment and consumed power ratio (ratio of pressure loss) seems to be better tan wen ReD = Tis means tat te average PEC in ReD = 3000 is iger tan tat for ReD = Te uncertainty analysis for E t, η e, E t, Figure 14. Uncertainty analysis in various and ηe as been carried out too. Te uncertainty for local quantities of Et and η e is smaller temperature points obtained from one sample of iterative tests tan 8% and for average quantities of Et and η e is 4-5% [12]. In fig. 14, te uncertainty analysis for various temperature points obtained from one sample of iterative tests is presented. For te case of active metod, te following correlations of various Reynolds numbers ave been constructed: (1) ReD = 500 : Arrangement 1: Arrangement 2: (2) ReD = 2000 : Arrangement 1: e IEHD IEHD IEHD η = (8) e IEHD IEHD IEHD η = (9) e IEHD IEHD IEHD η = (10)

10 514 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp (3) ReD = 3000 : Arrangement 1: Conclusions e IEHD IEHD IEHD η = (11) Arrangement 2: e IEHD IEHD IEHD η = (12) Tis study revolved around te enancement of eat transfer from flus-mounted ribbons in a cannel flow using an active metod. Two new parameters η e and I EHD ave been introduced. Te parameter of η e deals wit te simultaneous effects of eat transfer enancement and consumed power ratio (te pressure loss ratio) on te cooling performance. Te parameter I EHD embraces te interaction effects of EHD secondary flow and forced convection main flow togeter. Te parameter of I EHD is ratio of EHD flow term to forced convection main flow term and is similar to Ricardson number. Te following conclusions emanate from te experimental study are listed. Te power of corona wind (secondary flow) in low Reynolds flows is iger tan in ig Reynolds flows, signifying tat te corona wind in low Reynolds numbers is better tan in ig Reynolds numbers. Te active metod for low Reynolds numbers wit laminar flows is advantageous. Te average and local eat transfer enancement climbs up to 130% and 137%, respectively. For te same Reynolds numbers and wire arrangements, te eat transfer enancement was increased wit increments in voltage of te wire electrodes. At ig voltages, te density of electric carge and te electric field around of wire electrodes is ig. Terefore te corona wind in ig voltages as been affect on main flow better tan low voltages. In same Reynolds numbers and voltages of wires, te eat transfer enancement was increase in arrangement 1 tan oter arrangements. Density of electric carge around of wire electrodes in arrangement 1 is iger tan oter arrangements. Terefore, te arrangement 1 is better tan arrangements 2, 3, 4, and 5, respectively. Active metod for low Reynolds numbers as iger average PEC = Te power of corona wind in low Reynolds numbers is iger tan in ig Reynolds numbers. Terefore, te corona wind in low Reynolds numbers as been affect on main flow better tan in ig Reynolds number. For te boundary conditions used, te correlations for te average of PEC ( η e ) vs. EHD strengt ( I EHD ) for different Reynolds numbers can be introduced. Tese correlations sowed tat te effects of Reynolds numbers and arrangement on average of PEC. Density of electric carge around of wire electrodes in arrangement 1 is iger tan arrangement 2. Terefore te arrangement 1 is better tan arrangement 2. Te voltage of wire electrodes becomes constant after te corona wind. After corona, te voltage of wire electrodes can not canges and only electric current of wire electrodes canges. Tis penomenon as been ignored in most of numerical literature works. Wit decrements in te laminar Reynolds number, te interaction strengt of EHD secondary flow was increased. In turbulent Reynolds numbers, te interaction strengt of EHD flow was decreased.

11 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp Nomenclature A area of orifice, [m 2 ] b mobility of ions, [m 2 V 1 s 1 ] C distance between wire and ground electrodes, [m] D diameter of pipe, [m] d diameter of orifice, [m] D ydraulic diameter, [m] E t eat transfer enancement ratio E lost consumed power ratio E 0 electric field, [Vm 1 ] H cannel eigt, [m] eat transfer coefficient, [Wm 2 K 1 ] s eat transfer coefficient for plain case, [Wm 2 K 1 ] I 0 electric current of corona wind, [A] I EHD EHD strengt L widt of flus mounted ribbon, [m], caracteristic lengt, [m] L 1 lengt of upstream region, [m] L 2 lengt of downstream region, [m] N EHD EHD number P pressure, [Pa] q rib constant eat flux from flus mounted ribbon, [Wm 2 ] q e0 electric carge of one electron, [Coulomb] Re Reynolds number Re D Reynolds number based on ydraulic diameter r radius of wire electrode, [m] r eff effective radius of wire to ground electrode, [m] S separation between flus mounted ribbons, [m] T temperature, [K, C] u velocity, [ms 1 ] u i velocity of electric ions, [mgs 1 ] W widt of cannel, [m] x, y, z Cartesian co-ordinates Greek symbols α view angle between wire and ground electrodes β te ratio of orifice to pipe diameter η e performance evaluation criteria υ kinematics viscosity, [m 2 s 1 ] ρ f density of fluid, [kgm 3 ] ρ e density of electric carge, [kgm 3 ] Δ difference Subscripts f ref. w Superscripts fluid reference condition flus mounted ribbon wall " flux average References [1] Saini, M., Webb, R. L., Heat Rejection Limits of Air Cooled Plane Fin Heat for Computer Cooling, Proceedings, 8 t Intersociety Conf. on Termal and Termomecanical Penomena in Electronic Systems, San Diego, Cal., USA, 2002 [2] Saini, M., Webb, R. L., Validation of Models for Air Cooled Plane Fin Heat Sinks Used in Computer Cooling, Proceedings, 8 t Intersociety Conf. on Termal and Termomecanical Penomena in Electronic Systems, San Diego, Cal., USA, 2002 [3] Alamgolilou, A., Esmaeilzade, E., Experimental Investigation on Hydrodynamics and Heat Transfer of Fluid Flow into Cannel for Cooling of Rectangular Ribs by Passive and EHD Active Enancement Metods, J. Experimental Termal and Fluid Science, 38 (2012), Apr., pp [4] Alamgolilou, A., Esmaeilzade, E., Numerical Investigation on Effects of Secondary Flow into Duct for Cooling of te Ribs by Passive Enancement Metod, J. Enanced Heat Transfer, 19 (2008), 3, pp [5] Esmaeilzade, E., Alamgolilou, A., Numerical Investigation of Heat Transfer Enancement of Rectangular Ribs wit Constant Heat Flux Located in te Floor of a 3D Duct Flow, Asian J. Applied Sciences, 1 (2008), 4, pp [6] Fujisima, H., et al., Numerical Simulation of Tree dimensional EHD of Spiked-Electrode Electrostatic Precipitators, IEEE, 13 (2006), 1, pp [7] Oadi, M. M., et al., Heat Transfer Enancement of Laminar and Turbulent Pipe Flow via Corona Discarge, Int. Journal of Heat and Mass Transfer, 34 (1991), 3, pp [8] Kasayapanand, N., Kiatsiriroat, T., EHD enanced eat transfer in wavy cannel, International Communications in Heat and Mass Transfer, 32 (2005), 6, pp [9] Kasayapanand, N., Kiatsiriroat, T., Optimized Electrode Arrangement in Solar Air Heater, Proceedings, Renewable Energy Int. Conf., Gelsenkircen, Germany, 2006, Vol. 31, pp

12 516 THERMAL SCIENCE, Year 2016, Vol. 20, No. 2, pp [10] Kasayapanand, N., et al., Effect of te Electrode Arrangements in a Tube Bank on te Caracteristic of Ectroydrodynamic Heat Transfer Enancement: Low Reynolds Number, J. Enanced Heat Transfer, 9 (2002), 5-6, pp [11] Goo, J. H., Le, J. W., Stocastic Simulation of Particle Carging and Collection Caracteristics for a Wire-Plate Electrostatic Precipitator of Sort Lengt, J. Aerosol Science, 28 (1997), 5, pp [12] Moffat, R. J., Describing te Uncertainties in Exp. Results, Exp. Termal & Fluid Science, 1 (1988), 1, pp Paper submitted: May 18, 2013 Paper revised: September 4, 2013 Paper accepted: September 5, 2013