Thermal management with micro-architectured materials and metal foams

Transcription

1 Thermal management with micro-architecture materials an metal oams T. J. Lu Co-workers: T. Kim, C. Y. Zhao, an H. P. Hoson Sponsors: ONR, ONR IFO, EPSRC, an Porvair Lt. Engineering Department o / Engineering, University o Cambrige University o Cambrige

2 Outline - Utilisation o micro-architecture structure as a heat sink meium. 1. Analytical approach using two-equation moel. 2. Experimental results o pressure rop an heat transer measurements - Novel lightweight metal oams 1. Examples employing metal oams as a heat exchanger 2. Analytical approach using two-equation moel. 3. Experimental results o pressure rop an heat transer measurements The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

3 Heat sink moel using the LFMs Lattice-rame material (LFM)s are triangulate 3-D structures (Tetraheral cell base) Y Z Greater lateral stiness an lower cost per unit weight over honeycombs an metal oams Y b H c X - Surace area ensity : [1/m] l e a Sp - Relative ensity ( or porosity) : (0.938) Unit cell o the LFMs Force air convection heat transer measurements were conucte The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

4 Coniguration o Lattice-Frame Materials Two orientations enote as below were teste or heat transer an pressure rop measurements O-A O-B (a) Orientation-A (rontal view) Sz0 Sy0 Sx0 (b) Orientation-B (rontal view) (c) Crosslow arrangement o LFMs The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

5 Experimental conitions & set-up Speciication o LFM Typical operating parameter LFM cell bar iameter () m Inlet coolant mean velocity 1.0~26.0 m/s Longituinal cell pitch ( X 0 S ) m Bar Reynols number 120 Re 3200 Transverse cell pitch ( S ) m Input heat lux 4, 8 an 16 K Z0 Cell stut length (l) m Inlet coolant temperature 300 K W / m 2 Table o parameters or the current test Cell height (H) m Outlet coolant temperature K~360.0 K Material LM25 Test section inlet pressure 1 bar (ambient conition) Photograph o test rig an inserte LFM test sample The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

6 Governing Equations Momentum Equation 2 F 0 p u u u 2 x y K K Energy Equation k se C 2 y T 2 u s ha~ T x T Constant heat lux Flow an heat transer are ully evelope s ha~ T T T k e 2 s 2 T y 2 K = permeability = lui ensity F = inertial coeicient = porosity wette area ratio k se, k e = eective thermal conuctivity C = speciic heat o lui h = interstitial heat transer coeicient; The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

7 s T q w s H T / k se w T q w H T / k se w Re u m Y y H (a) (b) -2-1 Re = Re = Soli an lui temperature istributions or ierent Reynols numbers The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

8 Results o Hyraulic Resistance Friction Factor Orientation A (O-A) Orientation B (O-B) P L D 4(ρU h 2 m / 2) 10 0 Orientation-A -Reynols number base on LFM cell bar iameter Re ρ U / µ Operating range Orientation-B 120 Re Re The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

9 1 Coolant velocity at exit Coolant velocity at inlet (normalize) Channel height Velocity (m/s) Inrare thermal image o top LFM substrate showing linear increase o temperature in constant heat lux bounary conition Coolant velocity istributions along the channel height or both inlet an outlet o the test section The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

10 Average sselt number 450 Average temperature ierence O-B T avg n T i1 w,i / n T in O-A The best curve it or both orientations Dh =1.23(Re Dh ) 0.56 Pr 0.36 Heat transer coeicient h q / T avg or O-A: Input heat lux q = 4 KW/m 2 or O-A: Input heat lux q = 8 KW/m 2 or O-A: Input heat lux q = 16 KW/m 2 or O-B: Input heat lux q = 4 KW/m 2 or O-B: Input heat lux q = 8 KW/m 2 or O-B: Input heat lux q = 16 KW/m 2 Correlation or the LFMs Re Average sselt number hd h / k The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

11 Comparisons (a) orientation A experimental ata preiction with inertial eect preiction without inertial eect (b) orientation B experimental ata preiction with inertial eect preiction without inertial eect ,000 2,000 4, ,000 2,000 4,000 Re Comparison o overall sselt number with experimental ata Re h q T w T, b hd k h The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

12 Interstitial heat transer coeicient, h propose by Zukauskas or Staggere banks o cyliner array Staggere cyliners h Eect o yaw angle h 0.9h ' ' 1.04 Re 0.71Re 0.35 Re Pr Pr Pr k k k Re The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

13 Average sselt number 10 2 LFM (O-A) LFM (O-B) Correlations by Zukauskas (or Staggere BOCs) Empirical correlation or LFMs =0.428(Re ) 0.56 Pr 0.36 Reynols number base on cyliner bar iameter use. where Transition k h / 10 1 Re / U m 10 0 =1.04(Re ) 0.4 Pr 0.36 =0.71(Re ) 0.5 Pr 0.36 = 0.35(Re ) 0.6 Pr Re an Prantl number Pr is assume to be constant e.g The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

14 Comparisons with other heat sink meia (rom Kays an Lonon, Compact heat exchangers ) 10 0 x LFM: Orientation A LFM: Orientation B Bank o cyliners Wavy-in plate-in surace Cross-ro matrices, inline stacking Plain pin-in Ininitely ranomly stacke sphere matrix J-Colburn actor : I(=j/) 10-1 LFM O-B J St Pr 2 3 Re D h Eiciency Inex Pr Pr 2 3 x x x x x x x I = J / LFM O-A 10-2 Re Dh The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

15 (1) Detaile local heat transer mechanism is anticipate by using Thermochromic Liqui Crystal (TLC) / Inra Re imagings. Future Works (2) Construct heat sink esign parameters using LFMs e.g. cell size eects, number o stacke layers, aspect ratio o the heat sink channels etc. Heate air low Test section Ro Ri Flat black coating Liqui Crystal Perspex Traverse gears Air exits Liqui crystal coate Hollow cyliner Colour change o TLC is monitore rom insie o the cyliner Test rig or single cyliner an a ierent version o rig or LFMs will be constructe. The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

16 Light weight metal oam heat exchangers -Examples or heat exchanger application -Flow resistance -Thermal resistance The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

17 Fabrication o metal oam heat exchangers Metal oam compact heat exchanger or high temperature service. Foam material is PFCT's FeCrAlY. SEM micrograph o a oam strut sintere to a soli tube. Boning region shows metallurgical sintering between oam an soli. The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

18 Fabrication o metal oam heat exchangers Example assemblies manuacture in a proprietary co-sintering technique The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

19 SEM images o reticulate metal oam structure (FeCrAlY). Interconnecte tortuouspathways create turbulence in through-lowing luis. The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

20 Momentum Equation Governing Equations 2 F 0 P u u u Energy Equation K K 0 k x C T u x se T s x x ha~ T k y k k k k s e T se T s y T Fully evelope velocity iel Constant heart lux q x q w ha~ k T y e T y 2 s e T k se T y T y y0 y0 s a ~ = wette area ratio k = thermal ispersion conuctivity = C D Re k Pre u u m ke C D = 0.10 Re k K Pr an Ts T at y = 0 The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED e u m C ke k e = eective conuctivity; k e + k se F = inertial coeicient K C m n 2 / 1 P P where C= , m = , n = h 0.52 Re Pr k /

21 Results o Hyraulic Resistance P/L [kpa/m] - Static pressure rop per unit length S-1 S-2 S-3 S-4 S-5 S-6 S-7 60 ppi 60 ppi 5% relative ensity 10% relative ensity 30 ppi 10% relative ensity 30 ppi 7.5% relative ensity 10 ppi 10% relative ensity 30 ppi 5% relative ensity - Friction Factor P L 2ρ D h U 10 2 S-1: 5%, 10 PPI S-2: 10%, 10 PPI S-3: 5%, 30 PPI S-4: 10%, 30 PPI S-5: 5%, 60 PPI S-6: 10%, 60 PPI S-7: 7.5%, 30 PPI in ppi 5% relative ensity U m Operating range Re D h 3000 Re D h ρ UD h /µ Re Dh The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

22 Average sselt number, Case 1. ixe pore size as 30 PPI Case 2. ixe relative ensity as 10% S-3 S-4 S-7 30PPI 7.5% Relative ensity S-2 S-4 S-6 10 PPI 10% relative ensity PPI 10% Relative ensity PPI 10% relative ensity PPI 5% Relative ensity PPI 10% relative ensity avg Re Dh Heat transer parameters T n T i1 w,i /nt in h q / T avg an Re Dh hd h / k The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

23 U = u/u m Re K K Y y / H u m Re = 140 K 34 X = 0.5 U 3 2 Isolux ERG oam 5 ppi (Calmii an Mahajan, 2000) 80 T ( O C) T Ts Isolux ERG oam 5 ppi (Calmii an Mahajan, 200 Re = 80 K Y Re = 140 K Y Velocity an temperature istributions or ierent Reynols numbers The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

24 ( x) T w q T, b L k e X x L 1 L 0 L x x ERG oam 5 ppi (Calmii an Mahajan, 2000) Isolux Re = 140 K 15 numerical no thermal ispersion no axial conuction X Preictions o local an overall sselt numbers 5 analytical ERG oam 5 ppi (Calmii an Mahajan, Rek The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

25 Re u m D h ( x) T w q T, b D k h 1 L 0 L x x ERG oam 10 ppi 140 Re = Fecraly Re = pore size p = 4 mm ERG oam 10 ppi Fecraly Cell size p (mm) Variations o overall sselt number with pore size an porosity The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

26 Re u m D h q D L h ( x) Tw Tin k x L 0 1 x constant heat lux Relative ensity = 5% Fecraly k = 26 w/mk s 0.7 r = 0 10 ppi test ata constant heat lux Copper k = 372 w/mk s 0.7 r = 0 test ata relative ensity = 5% 10 ppi 50 2,000 4,000 6,000 8,000 10,000 12,000 14,000 Re 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 Re Variations o overall sselt numbers with Reynols numbers or Porvair material The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

27 ( x) T w q T, b D k h 1 L 0 L x x ERG oam Fecraly Re = ppi constant heat lux 150 ERG oam Fecraly 10 ppi constant heat lux 100 constant wall temperature 110 constant wall temperature X 50 2,000 4,000 6,000 8,000 10,000 12,000 14,000 Re Bounary eects on local an overall sselt numbers The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED

28 Comparisons with soli strut metal oams [rom Calmii et al. (2000)] X S-1, (10 ppi, 5%) S-2, (10 ppi, 10%) S-3, (30 ppi, 5%) S-4, (30 ppi, 10%) S-5, (60 ppi, 5%) S-6, (60 ppi, 10%) S-7, (30 ppi, 7.5%) Sample 1 o Al oam [Calmii et. al. (2000)] Sample 3 o Al oam [Calmii et. al (2000)] Sample 4 o Al oam [Calmii et. al. (2000)] X X X X X X X X Thermal conuctivity k S = 16 W/mK (FeCrAlY) ~ 160 W/mK (Al alloy, T-6201) sselt number base on hyraulic iameter X 10 % Relative ensity 7.5 % Relative ensity 5% Relative ensity Re Dh hd / k h where re, green an yellow ille symbols inicate 10%, 7.5% an 5% relative ensity, respectively The Engineering Cambrige Department Centre or / University Micromechanics o Cambrige & Whittle Laboratory CUED