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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 Florida January 03, 2008 – Falcuty of Applied Sciences – University of Technology, HCMC, Vietnam

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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

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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).

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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

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HVAC&R Applications Refrigerated Warehouse Hospital Operating Room

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

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Effective Viscosity Effective Thermal Conductivity Mixing Length Turbulence Model

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

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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

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Quadrilateral-Element Mesh ~ 35000 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

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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-

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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

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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.

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

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Axisymmetric Model and Dimensions

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Quadrilateral-Element Mesh ~ 18000 elements Refined regular mesh along fluid-solid interfaces Fine mesh at nozzle and inlet Pave mesh fills the rest of the domain

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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-

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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

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Effect of Nozzle Speed and Spraying Gap on Temperature

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

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3-D Model and Dimensions

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3-D Hexahedral-Element Mesh

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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 -

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

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Distribution of Temperature, K

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Maximum Temperature: 3-D vs. Axisymmetric Models

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

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Axisymmetric Model and Dimensions

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Quadrilateral-Element Mesh ~ 10000 elements Refined regular mesh along fluid-solid interfaces Fine mesh at nozzle and inlet Pave mesh fills the rest of the domain

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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-

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

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Maximum and Mean Temperatures vs. Elapsed Time in Stage 2

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

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

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2-D and 3-D Models

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

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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-

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

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

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Effect of Cooling Unit Location on Temperature Distribution

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

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

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2-D Quadrilateral-Element Mesh

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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 = 0.0148 Fan blades 1- -- 2 – 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---

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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

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

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

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

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Three-Dimensional Model

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3-D Hexahedral-Element Mesh

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

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Mesh Development for Indoor Environmental CFD Modeling

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Geometry Decomposition and Meshing for 2-D Model S = 0.1 m, H = 0.05 m, N = 3 and R = 1.5. 1496 square elements (58%) in total 2570 quadrilateral elements.

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Meshing 2-D Model using Encapsulation Techniques

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Geometry Decomposition for 3-D Model (1)

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Geometry Decomposition for 3-D Model (2)

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Meshing 3-D Model using Encapsulation Techniques (1)

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Meshing 3-D Model using Encapsulation Techniques (2)

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

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3-D Mesh: 35140 Cubical Elements (62%) in total of 56290 Hexahedral Elements

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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

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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 0.000167 mL/min 62 kPaLaser (2004) Proposed "MEMS" units 0.00278 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 = 0.002 Pa.s; r = 1.019 ÷ 1.063 g/mL ≈ 0.001 g/mm³ (# water) Assumption: Fully-liquid working fluid (well-primed, absolutely no gas bubble)

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

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Pump Chamber - Simulation Results

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Common actuator configurations

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Thermopneumatic Actuation Driver

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Thermopneumatic micropump based on PCB technology

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Temperature–Deflection Relationship of Diaphragm

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Actuation Chamber – Simulink Model

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Actuation Chamber - Simulation Results Experimental Result

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Complete Micropump – Simulink Model

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Complete Micropump – Simulation Results

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PCBs

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Questions?

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