Research Summary Groll Jan 2007 - Purdue Engineering · – Stirling cycle coolers ... unitary...

Purdue University - School of Mechanical Engineering

Ray W. Herrick LaboratoriesPurdue University

West Lafayette, IN 47907

Eckhard A. GrollProfessor of Mechanical Engineering

Summary of Research Activities


Main Driving Factors for Research are Energy and Environment

Transportation • automobiles, trucks, buses• planes, ships

Global WarmingAcid Rain

Industry• manufacturing• food processing• chemical processing


Commercial Residential • buildings• refrigeration


Ozone Depletion

Fossil Fuel Resources• oil• natural gas•coal

Fossil Fuel Resources• oil• natural gas• coal


Energy Conversion/Distribution

• power generation• electrical transmission• oil refining


Global WarmingAcid Rain









Ozone Depletion






Energy Conversion/Distribution

• power generation• electrical transmission• oil refining


Thermal System Research Area

Fundamentalsthermodynamics

heat transferfluids dynamics

mechanicscontrolssensors

Applications vapor compression

systems & componentsalternative ref. cycles

thermal storagebuildingsfurnaces

appliancesautomotive

power plants

Analysis Toolsmodeling

numerical methodsexperimental techniques

optimization methodsInformation technology

Thermal Systems Research

Group


Thermal Systems Strategic Plan

Recruit High Quality Graduate Students

Serve theHVAC&RIndustry

Thermal SystemsResearch Area

Heat Transfer

Fluids Thermodynamics

Machinery

Controls

Modeling Experiments

Optimization

problems

resources

solutions

engineers &researchers

knowledge

Critical Mass ofFaculty Expertise

International Reputation• Papers, short courses, conferences

• ASHRAE, ARI, IIR participation

AttractGovernment

Funding

solve fundamentalproblems

researchsupport

High QualityResearch Facilities

equipment grants

giftstesting contracts


Main Research Thrusts• Alternative Technologies for heat pumping, air conditioning,

refrigeration, drying, etc.: – Analysis of transcritical CO2-cycle technology (some details later on)– Evaluation of thermoelectric refrigeration and air conditioning– Stirling cycle coolers– Ericsson cycle coolers– Air-cycle technology (reversed Brayton cycle) for transport air

conditioning and drying applications.– Combined absorption/compression cycle (vapor compression cycle

with solution circuit) utilizing working pairs such as ammonia/water, CO2/Acetone, and HFC-23/DEGDME.


Main Research Thrusts, cont’d• Improved Components, such as compressors, heat exchangers,

expansion devices, distributors, etc.:– Modeling, analysis, and testing of positive displacement compressors

(some details later on)– Evaluation of scroll or screw compressors for the combined

compression of refrigerant vapor and solution in absorption/compression cycles

– Modeling, analysis, and testing of two-phase work output expansion machines

– Development of an improved method for refrigerant flow distribution– Analysis and design of heat exchangers– Heat transfer and pressure drop characteristics during in-tube gas-

cooling, condensation, and evaporation of new/substitute refrigerants– Performance evaluation and investigation of the fouling behavior of air-

to-refrigerant heat exchangers


Main Research Thrusts, cont’d• Improved Systems, (Air Conditioners and Heat Pumps,

Chillers, Refrigerators, Furnaces, etc.) through modeling optimization, reliability studies:– Improved steady-state design models for air conditioners and heat

pumps (some details later on)– Transient models unitary systems and chillers– HFCs and HFC mixtures as a replacement for R-22 in unitary air

conditioning and heat pumping equipment– Hydrocarbons and their mixtures as a replacement for HCFC-22 in

unitary equipment and as a replacement for R-134a in domestic refrigerator/freezers

– Secondary loop refrigeration systems using ammonia or hydrocarbons for commercial and unitary applications

– A cost-based methodology for determining optimal refrigerants– Impact of heat exchanger fouling on system performance


Main Research Thrusts, cont’d

• Miniature-Scale Refrigeration Systems (MSRS)for electronics cooling:– Performance evaluation of miniature-scale refrigeration systems for

electronics cooling (some details later on)– Modeling, analysis, design and testing of miniature-scale compressors

for electronics cooling– Evaluation of miniature-scale diaphragm compressors for electronics

cooling


Two Large Environmental Chambers• Testing of AC, HP and Refrig. Systems• -20 C to + 50 C, < 5-ton equipment• Steady-state and cyclic testing of existing,

modified, or new equipment designs

90-ton Centrifugal Chiller• Automated control of boundary conditions

Heat Exchanger Test Facility• Testing of coiling coils, heating coils,

evaporators, condensers• Capable of controlled heat exchanger

fouling

Compressor Load Stands• CO2, R-22, R-410a

Test Facilities

Refrigeration Coil

ElectricResistance Heaters

10,000 CFM Blowers (2-blower wheels)

SteamInjector

Perforated Floor


Alternative Refrigeration Technologies: Transcritical CO2 Cycle

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 1.5 2 2.5 3 3.5 4 4.5 5Pressure ratio p2/p1

Ove

rall

Isen

tropi

c Ef

ficie

ncy

[-]

Approx. p1: 1.76 [MPa]Approx. p1: 2.47 [MPa]Approx. p1: 3.12 [MPa]Approx. p1: 4.19 [MPa]Approx. p1: 4.81 [MPa]Measured p1: 1.76 [MPa]Measured p1: 2.47 [MPa]Measured p1: 3.12 [MPa]Measured p1: 4.19 [MPa]Measured p1: 4.81 [MPa]

ov.Is.eff=-2.78259157E-01+8.95484761E-03*p1-2.69714368E-02*p1^2+9.76968361E-04*p1^3+2.55739111E-01*p2-2.83526791E-02*p2^2+9.86399651E-04*p2^3+2.58389357E-02*p1*p2-9.84810719E-04*p1*p2^2-1.70586490E-04*p1^2*p2

where p1= suction pressure [MPa] and p2= discharge pressure [MPa]DTsh=14.6 K; stdev=2.3 K

CO2 Compressor Load Stand: Performance of CO2Prototype Compressor:


Alternative Refrigeration Technologies: Transcritical CO2 Cycle

-250 -200 -150 -100 -50 0 50103

104

2x104

h [kJ/kg]

P [k

Pa]

15.5°C

1.23°C

-11.8°C

-25°C

1

2345

6

7

8 Case 1

Case 2

Case 3

Expansion Work Output Machine:


Pressure transducers

Thermocouples

Photo-electric sensor

Improved Components:Scroll Compressor Analysis

600

900

1200

1500

1800

2100

2400

0 120 240 360 480 600 720 840 960 1080 1200

Orbiting angle [degree]

Pres

sure

[kP

a] ]

Model predictionMeasurements

Chamber 2

Chamber 4

Chamber 6 Chamber 7

Experimental Setup:Model Validation:


Improved Components:Beard-Pennock Variable-Stroke Compressor (1988)

3.5 4.0 4.5 5.0 5.51000

1200

1400

1600

1800

2000Tcond=40oC &Tevap=-15oC

Cooling Capacity EER

Swept Volume (cm3)

Coo

ling

Cap

acity

(Btu

/hr)

7.0

7.2

7.4

7.6

7.8

8.0

EE

R

Concept:

Predicted Performance:


Improved Components:Refrigerant Flow Distributor Analysis

Refrigerant Mal-distribution:CFD Modeling of

Refrigerant Flow Distribution

-40%

-30%

-20%

-10%

0%

10%

20%

30%

Type 2

Type 3 Type 4

Type 5

branch 1branch 2branch 3branch 4

branch 1branch 2branch 3branch 4

ε m,i

x 10

0 (%

)


Improved Components:Air-Side Heat Exchanger Fouling Analysis

Air-side Pressure Drop Fouling Factors (Measured)

Air-side Effective Heat Transfer Coefficient Fouling

Factor (Measured):

Air Vel = 2.5 m/s (500fpm)

0%

50%

100%

150%

200%

250%

MERV14 MERV11 MERV8 MERV6 MERV4 Nofilter

f dp

HX8WHX8LHX4LHX2L

Air Vel=2.54 m/s

, ,

,

100( )%c f c c

dpc c

P Pf

P∆ − ∆

=∆

Air Vel = 2.5 m/s (500fpm)

-16%

-14%

-12%

-10%

-8%

-6%

-4%

-2%

0%

2%

4%

6%MERV14 MERV11 MERV8 MERV6 MERV4 Nofilter

f h

HX8WHX8LHX4LHX2L

Air Vel =2.54 m /s

100( )%f c

hc

h hf

h−

=


Improved Systems:Secondary-Loop Refrigeration Systems

Supermarket Case Study:

COP 1.56

Low Temperature SL (R-717/HFE)

COP2.31

Medium Temperature SL

(R-717/HFE)

COP 1.19

Low Temperature DX (R-404A)

COP2.01

Medium Temperature DX

(R-22)


Target Operating Conditions

• Cooling capacity: ≥ 200W

• Evaporating temperature: 10 to 25 °C

• Condensing temperature: 40 to 55 °C

• Superheat: 3 to 8 °C

• Subcooling: 3 to 10 °C

• Ambient temperature: 25 to 45 °C

Microchannel Condenser

Cold Plate Evaporator

Expansion Device Compressor

Filter & Drier

Sight Glass

Capillary Tube

Ball Valves

Pcomp,o PG

PG

DC Fan

Heat SpreaderHeating

copper block

F

Heaters

Tcomp,o

Pcomp,i PGTcomp,i

Pcond,o Tcond,iTcond,o

Pexp,i Texp,i

Texp

Compressor

Expansion devices

Cold plate evaporator

Simulated CPU

Condenser fansAir heater

Condenser

DC rotary compressor; φ 85 mm & 166 mm height & 2.8 kg weight

,o

PG

Pevap,i Tevap,iTevap,o

Tc1 Tc4Tc2 Tc3

PG Pressure Guage

CPU Size of 20x20 mm2

T Thermocouple

F Flow meter

P Pressure Transducer

PitotTube

Thermocouples Thermocouples Thermocouples

Heater

Air Inlet Air Outlet

Oil separator

Miniature-Scale Refrigeration System (MSRS)


Future Research Opportunities

Energy efficiency improvementsAlternative technologiesPerformance monitoring &

diagnosticsIntelligent controlsIntegrated facility managementHuman perception and productivityDistributed power generationImproved food production,

preservation, transportation, and storage

Small-scale refrigeration systemsLow temperature system / cryogenics

Global warmingUtility deregulationLimited generating capacityInformation technologiesConsolidation of service

providersWorker ProductivityLow-cost sensors & computersPopulation GrowthFood Quality DemandsElectronic cooling needsMedical needs

Research DirectionsDriving Factors

Research Summary Groll Jan 2007 - Purdue Engineering · – Stirling cycle coolers ... unitary...

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