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

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

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).

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

HVAC&R Applications Refrigerated Warehouse Hospital Operating Room

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

Effective Viscosity Effective Thermal Conductivity Mixing Length Turbulence Model

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

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

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

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-

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

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.

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

Axisymmetric Model and Dimensions

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

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-

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

Effect of Nozzle Speed and Spraying Gap on Temperature

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

3-D Model and Dimensions

3-D Hexahedral-Element Mesh

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 -

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

Distribution of Temperature, K

Maximum Temperature: 3-D vs. Axisymmetric Models

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

Axisymmetric Model and Dimensions

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

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-

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

Maximum and Mean Temperatures vs. Elapsed Time in Stage 2

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

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

2-D and 3-D Models

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

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-

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

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

Effect of Cooling Unit Location on Temperature Distribution

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

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

2-D Quadrilateral-Element Mesh

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---

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

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

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

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

Three-Dimensional Model

3-D Hexahedral-Element Mesh

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

Mesh Development for Indoor Environmental CFD Modeling

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.

Meshing 2-D Model using Encapsulation Techniques

Geometry Decomposition for 3-D Model (1)

Geometry Decomposition for 3-D Model (2)

Meshing 3-D Model using Encapsulation Techniques (1)

Meshing 3-D Model using Encapsulation Techniques (2)

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

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

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

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)

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

Pump Chamber - Simulation Results

Common actuator configurations

Thermopneumatic Actuation Driver

Thermopneumatic micropump based on PCB technology

Temperature–Deflection Relationship of Diaphragm

Actuation Chamber – Simulink Model

Actuation Chamber - Simulation Results Experimental Result

Complete Micropump – Simulink Model

Complete Micropump – Simulation Results

PCBs

Questions?