research summary groll jan 2007 - purdue engineering · – stirling cycle coolers ... unitary...
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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
Purdue University - School of Mechanical Engineering
Main Driving Factors for Research are Energy and Environment
Transportation • automobiles, trucks, buses• planes, ships
Global WarmingAcid Rain
Industry• manufacturing• food processing• chemical processing
Industry• manufacturing• food processing• chemical processing
Commercial Residential • buildings• refrigeration
Commercial Residential • buildings• refrigeration
Ozone Depletion
Fossil Fuel Resources• oil• natural gas•coal
Fossil Fuel Resources• oil• natural gas• coal
Transportation • automobiles, trucks, buses• planes, ships
Energy Conversion/Distribution
• power generation• electrical transmission• oil refining
Transportation • automobiles, trucks, buses• planes, ships
Global WarmingAcid Rain
Industry• manufacturing• food processing• chemical processing
Industry• manufacturing• food processing• chemical processing
Industry• manufacturing• food processing• chemical processing
Industry• manufacturing• food processing• chemical processing
Commercial Residential • buildings• refrigeration
Commercial Residential • buildings• refrigeration
Commercial Residential • buildings• refrigeration
Commercial Residential • buildings• refrigeration
Ozone Depletion
Fossil Fuel Resources• oil• natural gas•coal
Fossil Fuel Resources• oil• natural gas• coal
Fossil Fuel Resources• oil• natural gas•coal
Fossil Fuel Resources• oil• natural gas• coal
Transportation • automobiles, trucks, buses• planes, ships
Energy Conversion/Distribution
• power generation• electrical transmission• oil refining
Purdue University - School of Mechanical Engineering
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
Purdue University - School of Mechanical Engineering
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
Purdue University - School of Mechanical Engineering
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.
Purdue University - School of Mechanical Engineering
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
Purdue University - School of Mechanical Engineering
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
Purdue University - School of Mechanical Engineering
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
Purdue University - School of Mechanical Engineering
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
Purdue University - School of Mechanical Engineering
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:
Purdue University - School of Mechanical Engineering
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:
Purdue University - School of Mechanical Engineering
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:
Purdue University - School of Mechanical Engineering
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:
Purdue University - School of Mechanical Engineering
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 (%
)
Purdue University - School of Mechanical Engineering
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−
=
Purdue University - School of Mechanical Engineering
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)
Purdue University - School of Mechanical Engineering
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)
Purdue University - School of Mechanical Engineering
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