Summer 2013 Internship Exit Presentation

Matt Stinson Heat Transfer Group

7/26/2013

Mentor: Luzeng Zhang

Heat Transfer Manager: Hee-Koo Moon

Harbor Drive Evacuation Map

Presentation Outline

• Personal Background

• Projects – Heat Exchanger Addition to Scaled Cascade Rig

– Phantom Cooling Data Processing and Analysis • Experimental – Pressure Sensitive Paint

• Numerical – CFD

• Summer Fun

• Acknowledgements

• Questions

Personal Background

• From Federal Way, WA

• Education – B.S. in ME (2009), Purdue University

• Minor in EE

– Ph.D. in ME (2014), University of Minnesota • Minor in AE

• Studying film-cooling on turbine endwalls

Heat Exchanger Addition to Scaled Cascade Rig

• Background – Scaled cascade utilizes pressure

sensitive paint technique – High temperatures in tunnel leads to

low luminescent intensity and relatively high noise level

– Facility use is limited to winter months

• Objectives – Research and design/select a heat

exchanger to cool air in wind tunnel – Consider various coolant sources – Design how heat exchanger fits into

current system

T-250 Stage 1 Nozzle Cascade Schematic of Scaled Cascade Rig

Specific Requirements/Goals

• Heat exchanger requirements – Air flow rates up to 7000 SCFM at 10 psig

– Cool air by at least 30 F / below 170 F

– Limit air side pressure drop to 0.5 psi

Spencer Blower Temperature Outlet Curve (Inlet T = 68 F)

Required ~10 F cooling @ T_in = 68 F

Additional ~20 F cooling @ T_in = 88 F

Heat Exchanger Design

• Design basics – Thermally balanced

designs are most economical •

– Finned surfaces tend to be more economical, but limit operating conditions

ch hAhA )()( =

Shell and Tube Heat Exchanger

Tube-Fin Heat Exchanger

Plate-Fin Heat Exchanger

Tube-Fin Heat Exchanger

• Commonly used in car radiators and HVAC applications

• Cross-flow arrangement

• Individually finned – Rugged – High heat transfer

• Continuously finned – Inexpensive – Low pressure drop

Left: Individual fins, Right: Continuous plate fins

Will it work?

• Example performance – Fixed tube-fin layout

– Variable rows

– Variable face area

– Variable water coolant

– Inlet Conditions: • Air: 7000 SCFM,

pin = 10 psig, Tin = 200 F

• Water: Tin = 85 F

• Relationships –

– 2fr

rows

ANp ∝∆

rowsfr NAT 5.0∝∆

0 10 20 30 40 50 60 70 80 90 1000

10

20

30

40

50

60

70

80

90

100

gal/min

Tem

pera

ture

dro

p, F

Heat Exchanger Performance

L=24", N=2, pdrop=0.020 psiL=24", N=6, pdrop=0.058 psiL=36", N=2, pdrop=0.005 psiL=36", N=6, pdrop=0.013 psiL=30", N=4, pdrop=0.017 psi

Selected Heat Exchanger

• Design conditions – Air

• 8000 SCFM • Tin = 200 F, pin = 10 psig

– Water • Tin = 85 F

• Air-side performance – Δp = 0.07 psi

• Water-side performance – Δp = 2.5 psi @ 25 gpm

• Heat exchanger specs – Weight = 500 lb – Flange-to-flange = 50” – Max Width = 46” – Price: $8000 0

5

10

15

20

25

30

35

40

45

50

20 25 30 35 40

Air

Tem

pera

ture

Dro

p, F

Water Flow, gal/min

Heat Exchanger Performance

Treated Water

Intermediate Fouling

Untreated Water

Coolant Source

1. Cooling tower water • Evaporative cooling

• Already in service

• Capable of meeting coolant demands

• Fouling concerns

2. Closed loop chiller • Significant footprint

• Increased costs

• No fouling concerns

Fouling Control

• Fouling control steps – 1/8” mesh screen pre-filter

• Protects against macrofouling

– Copper tubes • Naturally antimicrobial, controls

biofouling • Smooth-walled material, slow to

foul

– Maintain flow rates above 4 ft/s (25 GPM) • High shear stress, controls fouling

buildup

– Maximum water temperature maintained below 140 F • Controls precipitation fouling

Limescale

Biofoul

Corrosion Control and Maintenance

• Corrosion control steps – Insulating connectors at heat

exchanger inlet/outlet • Protects against galvanic

corrosion

– Maintain water flow rates less than 6 ft/s (37.5 gpm) • Protects against erosion

corrosion

• Maintenance recommendations – Cycle water at least twice a

week • Controls against corrosion and

biofilm buildup

Galvanic corrosion

Erosion corrosion around a bend

Heat Exchanger Location Options

Current Blower and Ducting Installation

1. On Roof – Easy access – Roof supports heat

exchanger – Section needed for

venturi flow straightener

2. At blower outlet – Structure required to

support heat exchanger

3. At blower inlet – Structure required to

support heat exchanger – Ducting unchanged – No driving temperature

difference

Heat Exchanger Installation

Making room in ducting for Heat Exchanger Heat Exchanger Installation Location

Heat Exchanger Support Table

Table to support heat exchanger

Table Safety Rails and Stairs

Table safety rails and stair installation

Street View

View Including Solar Perimeter Fence

Phantom Cooling

• Background – Phantom cooling is a branch of film

cooling in which secondary flows are doing the cooling • Examples

1. Nozzle surface coolant cools the adjacent endwall surface

2. Nozzle surface coolant cools downstream blade surface

– Understanding phantom cooling leads to more optimized cooling schemes

• Objectives – PSP

• Clean up PSP results for display

– CFD • Build macro to extract spanwise averaged

temperatures along blade surface • Determine blade surface adiabatic

effectiveness • Run additional CFD cases to determine

maximum cooling

Spent nozzle coolant cooling blade suction surface PS and SS coolant cooling the endwall surface

PSP Image Processing

• Used matlab script to clean noise – Optimized old matlab script

• 2 min process 10 sec

• Got experience with Tecplot

Figures prior to cleaning Figures after cleaning

Showerhead (SH1-6)

Pressure side (PS1)

Suction side (SS1)

Suction side (SS2)

CFD Analysis

Top View of T-65 Blade Cascade Model with eight cooling hole positions

Cooling ejection cylinder a) VR=0.4, b) VR=0.5, c) VR=0.6

Velocity triangle analysis

CFD Postprocessing

• CFD result files – Built macro to extract spanwise averaged temperature along wall

• Sample results – VR = 0.4, hole position 6

Velocity Streamlines at blade mid-span Temperature contour at blade mid-span

Blade Surface Effectiveness

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

-1.5 -1 -0.5 0 0.5 1 1.5 2

eta

PS s/C SS

Average Blade Wall Adiabatic Effectiveness (Definition 1)

VR04

VR05

VR06

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

-1.5 -1 -0.5 0 0.5 1 1.5 2

eta

PS s/C SS

Average Blade Wall Adiabatic Effectiveness (Definition 2)

VR04

VR05

VR06

00

0

∞

∞

−−

=TTTT

c

awawη

rc

rawaw TT

TT

∞

∞

−−

=0

η

pr c

VrTT2

)1(2

0∞

∞∞ −−=

3 Pr≈r

Definition 1: Approximate definition

Definition 2: Proper definition

Summer Fun

• Taco Tuesday

• Hiking – El Cajon

– Cowles Mountain

– Mount Woodson

– Torrey Pines

– Iron Mountain

– Three Sisters

• San Diego Zoo

• Scenery

• Weather

Acknowledgements

• Thank you to the following: – Luzeng Zhang

– Hee-Koo Moon

– John Mason

– Gail Doore

– Eric Eggett

– Don Mariani

– Juan Yin

– Kevin Liu

– Archie French

– Tim Bridgeman

– Don Leroux

– Rotation Engineers

– Fellow Interns

– UTSR Program

– Kelsey Stinson

Questions