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Numerical Modeling and Simulation for Analysis of Fluid Flow and Heat and Mass Transfer in Engineering Applications Son H. Ho, Ph.D. University of South.

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Presentation on theme: "Numerical Modeling and Simulation for Analysis of Fluid Flow and Heat and Mass Transfer in Engineering Applications Son H. Ho, Ph.D. University of South."— Presentation transcript:

1 Numerical Modeling and Simulation for Analysis of Fluid Flow and Heat and Mass Transfer in Engineering Applications Son H. Ho, Ph.D. University of South Florida January 03, 2008 – Falcuty of Applied Sciences – University of Technology, HCMC, Vietnam

2 Agenda 1.Zero Boil-Off (ZBO) Storage of Cryogenic Liquid Hydrogen (LH2) 2.HVAC&R Indoor Spaces – Thermal Comfort and Contaminant Removal a.Refrigerated Warehouse b.Air-Conditioned Room with Ceiling Fan c.Hospital Operating Room 3.Microfluidic Systems – Micropumps 4.Portable Blood Cooling System – Chillinders

3 LH2 in Automotive Applications Hydrogen tank in car’s trunk.2005 Honda FCX fuel cell concept car. Shelby Cobras (Hydrogen Car Co.)Hydrogen Hummer (converted by Intergalactic Hydrogen).

4 LH2 in Space Applications Centaur upper stage – liquid hydrogen/liquid oxygen propelled rocket Transport of liquid hydrogen used in space applications. Hydrogen fuel cell for power supply

5 HVAC&R Applications Refrigerated Warehouse Hospital Operating Room

6 Governing Equations Conservation of mass: Conservation of momentum: Conservation of energy: Conservation of mass for water vapor: Conservation of mass for contaminant gas:

7 Effective Viscosity Effective Thermal Conductivity Mixing Length Turbulence Model

8 Cryogenic Liquid Hydrogen Storage Tank with Arrays of Injection Nozzles Fluid: LH2 Axisymmetric Model Steady-State Analysis

9 Model and Dimensions Lengthm A1.50 B0.65 C1.30 G0.05 M0.01 N0.02 P D, H, Lvar. F, Q(*) (*) F = D/√2 Q = [L – (M+N+P)]/2

10 Quadrilateral-Element Mesh ~ elements Refined regular mesh along fluid-solid interfaces Fine mesh at nozzle openings Map mesh inside inlet tube and nozzle head Pave mesh fills the rest of the domain

11 Boundary Conditions BoundaryVelocity, m/s Temperature, K Heat flux, W/m 2 Tank wallu r = u z = 0q = 1 Inletu r = 0, u z = 0.01 T = 18 Centerlineu r = 0q = 0 Nozzle head wall u r = u z = 0-

12 Velocity and Temperature Distributions Simulation #1 “BASE” (H = 1.3 m, D = 0.15 m, L = 1.0 m) Streamlines and Speed, m/s Temperature, K

13 Effects of Nozzle Depth As the depth H of the nozzle head increases, mean temperature decreases gradually but maximum temperature decreases then increases and has lowest value at the middle of the tank. Design: H ≈ 1.3 m for 2.6m- height tank.

14 Cryogenic Liquid Hydrogen Storage Tank with Array of Pump-Nozzle Units Fluid: LH2 Axisymmetric Model Steady-State Analysis

15 Axisymmetric Model and Dimensions

16 Quadrilateral-Element Mesh ~ elements Refined regular mesh along fluid-solid interfaces Fine mesh at nozzle and inlet Pave mesh fills the rest of the domain

17 Boundary Conditions BoundaryVelocity, m/sTemperatureHe at flux Tank wallu r = u z = 0q = 1 W/m² Centerlineu r = 0q = 0 Adiabatic section of heat pipe u r = u z = 0q = 0 Evaporator section of heat pipe u r = u z = 0T = 20 K Pump wallu r = u z = 0- Nozzle faceu z = 0, u r = -V-

18 Velocity and Temperature Distributions Simulation #1 “BASE” (G = 0.2 m, H = 1.5 m, P = 0.55 m) Streamlines and Speed, m/s Temperature, K

19 Effect of Nozzle Speed and Spraying Gap on Temperature

20 Cryogenic Liquid Hydrogen Storage Tank with Lateral Pump-Nozzle Unit Fluid: LH2 3-D Model Steady-State Analysis

21 3-D Model and Dimensions

22 3-D Hexahedral-Element Mesh

23 Boundary Conditions EntityVelocity, m/s Temperature, K Flux, W/m 2 Wall0q = 2.0 Symmetry planeu y = 0q = 0 H.P. adiabatic section0q = 0 H.P. evaporator sect.0T = 18 Suction-tube wall0q = 0 Pump-body wall0q = 0.01 Nozzle wall0q = 0 Nozzle face (V: normal velocity at nozzle face) u x = -V, u y = u z = 0 -

24 Distribution of Velocity, m/s Streamlines Speed Velocity vector and speed

25 Distribution of Temperature, K

26 Maximum Temperature: 3-D vs. Axisymmetric Models

27 Cryogenic Liquid Hydrogen Storage Tank with Axial Pump-Nozzle Unit Fluid: LH2 Axisymmetric Model Transient Analysis

28 Axisymmetric Model and Dimensions

29 Quadrilateral-Element Mesh ~ elements Refined regular mesh along fluid-solid interfaces Fine mesh at nozzle and inlet Pave mesh fills the rest of the domain

30 Boundary Conditions BoundaryVelocity, m/sTemperature/ Heat flux Tank wallu r = u z = 0q = 1 W/m² Centerlineu r = 0q = 0 Adiabatic section of heat pipe u r = u z = 0q = 0 Evaporator section of heat pipe u r = u z = 0T = 20 K Pump wallu r = u z = 0- Nozzle faceu z = 0, u r = -V-

31 Velocity and Temperature Distributions Stage 2, 5 minutes Streamlines and Speed, m/s Temperature, K

32 Maximum and Mean Temperatures vs. Elapsed Time in Stage 2

33 Maximum and Mean Temperatures vs. Elapsed Time in 3 First Cycles

34 Refrigerated Warehouse with Ceiling Type Cooling Unit Fluid: Air Two- and Three-Dimensional Models Steady-State Analysis

35 2-D and 3-D Models

36 2-D and 3-D Mesh Quadrilateral Elements Hexahedral Elements

37 Boundary Conditions EntityVelocity, m/sTemp., o C or Flux, W/m 2 Evap. outletu x = V, u y = 0T = 0 Flooru x = u y = 0q=h 6-in concrete (T ground -T) Walls/Ceilingu x = u y = 0q=h 4-in PUR (T ambient -T) Lights (ceil.)u x = u y = 0q = 10 Packagesu x = u y = 0- Evap. coveru x = u y = 0-

38 Streamlines and Speed, m/sTemperature, °C 2-D Simulation Results

39 3-D Simulation Results (a) Streamlines. (b) Speed, m/s. (c) Pressure, Pa.(d) Temperature, °C.

40 Effect of Cooling Unit Location on Temperature Distribution

41 Thermal Comfort Enhancement using Ceiling Fan in Air-Conditioned Room Fluid: Air Mixture (dry air + water vapor) Two-Dimensional Model Steady-State Analysis

42 2-D Model of Air-Conditioned Room with Ceiling Fan

43 2-D Quadrilateral-Element Mesh

44 Boundary Conditions EntityCase # Velocity, m/s Temp., o C Flux, W/m 2 W. Vapor, ~ Flux, kg/m 2.s Inlet1 – 4u x = 1, u y = 0T = 22w = Fan blades – 4u x = 0,u y = -V Fan motor 1 0 q = 0 q w = 0 2 – 4q = 10 Lights1 – 40q = 300q w = 0 Person1 – 40T = 34q w = 5E-7 Outlet1 – 4---

45 Simulation Results Streamlines and speed, m/s. Temperature, °C. Streamlines and speed, m/s. Temperature, °C. (a) Ceiling fan not running(b) Ceiling fan running

46 Effect of Fan Normal Air Speed on Mean Temperature and Thermal Comfort Mean temperaturePredicted mean vote (PMV)

47 PMV Distributions (a) Ceiling fan not running(b) Ceiling fan running

48 Thermal Comfort and Contaminant Removal in Hospital Operating Room Fluid: Air Mixture (dry air + water vapor + contaminant gas) Three-Dimensional Model Steady-State Analysis

49 Three-Dimensional Model

50 3-D Hexahedral-Element Mesh

51 3-D Simulation Results StreamlinesSpeed, m/s Temperature, °CContaminant concentration, mg/kg air

52 Mesh Development for Indoor Environmental CFD Modeling

53 Geometry Decomposition and Meshing for 2-D Model S = 0.1 m, H = 0.05 m, N = 3 and R = square elements (58%) in total 2570 quadrilateral elements.

54 Meshing 2-D Model using Encapsulation Techniques

55 Geometry Decomposition for 3-D Model (1)

56 Geometry Decomposition for 3-D Model (2)

57 Meshing 3-D Model using Encapsulation Techniques (1)

58 Meshing 3-D Model using Encapsulation Techniques (2)

59 3-D Mesh: Layers of Refined Element Mesh on Fluid-Solid Interfaces

60 3-D Mesh: Cubical Elements (62%) in total of Hexahedral Elements

61 Diaphragm Micropump Destination Inlet valveOutlet valve Pump chamber p1p1 p2p2 ss 1122 dd Diaphragm Source 1 22 Valve discs z V dead ΔV = V s1 + V s2 p2*p2* p1*p1* p(t)p(t) p(t)p(t) V s2 V s1 ΔVΔV 22 11

62 Design Requirements Flow rate, QPressure Δp in-out Notes Requirements10 μL/h9 psi SI units2.78×10‾¹² m³/s62×10³ Pa Units in review paper mL/min 62 kPaLaser (2004) Proposed "MEMS" units mm³/s (μL/s) 62×10³ PaAppendix A Size not exceed 1 in × 1 in = 25.4 mm × 25.4 mm. Interstitial fluid (ISF): m = Pa.s; r = ÷ g/mL ≈ g/mm³ (# water) Assumption: Fully-liquid working fluid (well-primed, absolutely no gas bubble)

63 Pump Chamber – Simulink Model R 0 Δ p valve ΔpΔp 1

64 Pump Chamber - Simulation Results

65 Common actuator configurations

66 Thermopneumatic Actuation Driver

67 Thermopneumatic micropump based on PCB technology

68 Temperature–Deflection Relationship of Diaphragm

69 Actuation Chamber – Simulink Model

70 Actuation Chamber - Simulation Results Experimental Result

71 Complete Micropump – Simulink Model

72 Complete Micropump – Simulation Results

73 PCBs

74 Questions?


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