Summary of Research Activities. Eckhard A. Groll Professor of Mechanical Engineering

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1 Summary of Research Activities Eckhard A. Groll Professor of Mechanical Engineering Ray W. Herrick Laboratories Purdue University West Lafayette, IN 47907

2 Main Driving Factors for Research are Energy and Environment Ozone Depletion Commercial Residential buildings refrigeration Industry Industry manufacturing manufacturing food processing food processing chemical processing chemical processing Energy Conversion /Distribution power generation electrical transmission oil refining Global Warming Acid Rain Fossil Fossil Fuel Fuel Resources Resources oil oil natural natural gas gas coal coal Transportation Transportation automobiles, automobiles, trucks, trucks, buses buses planes, planes, ships ships

3 Thermal System Research Area Fundamentals thermodynamics heat transfer fluids dynamics mechanics controls sensors Thermal Systems Research Group Applications vapor compression systems & components alternative ref. cycles thermal storage buildings furnaces appliances automotive power plants Analysis Tools modeling numerical methods experimental techniques optimization methods Information technology

4 Thermal Systems Strategic Plan International Reputation Papers, short courses, conferences ASHRAE, ARI, IIR participation Critical Mass of Faculty Expertise problems resources Serve the HVAC&R Industry Recruit High Quality Graduate Students solve fundamental problems Attract Government Funding research support Fluids Heat Transfer Thermodynamics Machinery Thermal Systems Research Area Modeling equipment grants Controls Experiments Optimization knowledge engineers & researchers solutions gifts testing contracts High Quality Research Facilities

5 Main Research Thrusts Alternative Technologies for heat pumping, air conditioning, refrigeration, drying, etc.: Analysis of transcritical CO 2 -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, CO 2 /Acetone, and HFC-23/DEGDME.

6 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 gascooling, condensation, and evaporation of new/substitute refrigerants Performance evaluation and investigation of the fouling behavior of airto-refrigerant heat exchangers

7 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

8 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

9 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 CO 2, R-22, R-410a Test Facilities Perforated Floor Refrigeration Coil 10,000 CFM Blowers (2-blower wheels) Electric Resistance Heaters Steam Injector

10 Alternative Refrigeration Technologies: Transcritical CO 2 Cycle CO 2 Compressor Load Stand: Performance of CO 2 Prototype Compressor: Overall Isentropic Efficiency [-] ov.is.eff= e e-03*p e- 02*p1^ E-04*p1^ E-01*p E- 02*p2^ E-04*p2^ E-02*p1*p E- 04*p1*p2^ E-04*p1^2*p2 where p1= suction pressure [MPa] and p2= discharge pressure [MPa] DTsh=14.6 K; stdev=2.3 K 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] Pressure ratio p2/p1

11 Alternative Refrigeration Technologies: Transcritical CO 2 Cycle Expansion Work Output Machine: 2x10 4 Case C P [kpa] 1.23 C C -25 C Case Case h [kj/kg]

12 Improved Components: Scroll Compressor Analysis Experimental Setup: Model Validation: 2400 Thermocouples 2100 M odel prediction M easurements Chamber 6 Chamber 7 Pressure transducers Pressure [kpa] ] Photo-electric sensor 900 Chamber 2 Chamber Orbiting angle [degree]

13 Improved Components: Beard-Pennock Variable-Stroke Compressor (1988) Concept: Predicted Performance: 2000 T cond =40 o C &T evap =-15 o C 8.0 Cooling Capacity (Btu/hr) Cooling Capacity EER EER Swept Volume (cm 3 )

14 Improved Components: Refrigerant Flow Distributor Analysis CFD Modeling of Refrigerant Flow Distribution Refrigerant Mal-distribution: ε m,i x 100 (%) 30% 20% 10% 0% -10% -20% -30% -40% Type 2 Type 3 Type 4 Type 5 branch 1 branch 2 branch 3 branch 4

15 Improved Components: Air-Side Heat Exchanger Fouling Analysis Air-side Effective Heat Transfer Coefficient Fouling Factor (Measured): Air-side Pressure Drop Fouling Factors (Measured) fh 6% 4% 2% 0% -2% -4% -6% -8% -10% -12% -14% -16% MERV14 MERV11 MERV8 MERV6 MERV4 Nofilter HX8W HX8L HX4L Air Air Vel Vel =2.54 = 2.5 m/s m/s (500fpm) HX2L f h 100( hf hc) = % h c 250% 200% 150% 100% 50% 0% fdp HX8W HX8L Air Air Vel=2.54 = m/s (500fpm) HX4L HX2L MERV14 MERV11 MERV8 MERV6 MERV4 Nofilter f dp = 100( Pc, f Pc, c) % P cc,

16 Improved Systems: Secondary-Loop Refrigeration Systems Supermarket Case Study: Medium Temperature DX (R-22) Low Temperature DX (R-404A) COP 2.01 COP 1.19 Medium Temperature SL (R-717/HFE) Low Temperature SL (R-717/HFE) COP 2.31 COP 1.56

17 Miniature-Scale Refrigeration System (MSRS) Air heater P exp,i Air Inlet Texp,i Filter & Drier Sight Glass Capillary Tube Ball Valves Expansion devices Texp,o Heater P cond,o PG Expansion Device Heating copper block Condenser Thermocouples Thermocouples Tcond,o F PG Heaters Microchannel Condenser Cold Plate Evaporator Compressor Cold plate evaporator Simulated CPU T cond,i Pevap,i T evap,i T evap,o T c1 T c2 Condenser fans Thermocouples P comp,o Pcomp,i Heat Spreader Tc3 Pitot Tube Oil separator Tc4 Tcomp,o T comp,i DC Fan PG Compressor PG PG P T F Air Outlet Pressure Guage Pressure Transducer Thermocouple Flow meter CPU Size of 20x20 mm 2 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 DC rotary compressor; φ 85 mm & 166 mm height & 2.8 kg weight

18 Future Research Opportunities Driving Factors Global warming Utility deregulation Limited generating capacity Information technologies Consolidation of service providers Worker Productivity Low-cost sensors & computers Population Growth Food Quality Demands Electronic cooling needs Medical needs Research Directions Energy efficiency improvements Alternative technologies Performance monitoring & diagnostics Intelligent controls Integrated facility management Human perception and productivity Distributed power generation Improved food production, preservation, transportation, and storage Small-scale refrigeration systems Low temperature system / cryogenics