A FREE-PISTON STIRLING CYCLE UNITARY HEAT PUMP SYSTEM

THE OBJECTIVE OF THIS RESEARCH IS TO DEVELOP AND TEST A PROOF-OF-PRINCIPLE DEMONSTRATION MODEL OF AN ELECTRICALLY DRIVEN STIRLING CYCLE UNITARY HEAT PUMP/AIR CONDITIONING SYSTEM, REPRESENTING A POSSIBLE INNOVATIVE ALTERNATIVE TO THE CONVENTIONAL VAPOR COMPRESSION UNITS CURRENTLY EMPLOYED IN RESIDENTIAL SIZED SYSTEMS. A MAJOR ADVANTAGE OF THIS CONCEPT IS THE FACT THAT NO OZONE DEPLETING CHLOROFLUOROCARBONS (CFCS) ARE REQUIRED IN THE STIRLING CYCLE. OTHER ADVANTAGES OF THE STIRLING CYCLE INCLUDE: (1) COMPETITIVE COEFFICIENTS OF PERFORMANCE (COP) IN THE HEATINGMODE AND ENERGY EFFICIENCY RATINGS (EER) IN THE COOLING MODE, (2) SIGNIFICANTLY HIGHER HEATING CAPACITY AT LOWER AMBIENT AIR TEMPERATURES, AND (3) A NUMBER OF UNIQUE OPERATING MODES THAT WILL ALLOW THE SYSTEM TO PROVIDE SUPERIOR COMFORT CONDITIONING. THE STIRLING SYSTEM IS A FREE-PISTON/LINEAR ALTERNATOR (FPLA) TYPE THAT OVERCOMES THEBASIC MECHANICAL SEALING AND MECHANISM COMPLEXITY OF KINEMATIC STIRLING CYCLE MACHINES. FLEXURAL BEARINGS ARE EMPLOYED AS A LOW COST ALTERNATIVE TO GAS BEARINGS TO PROVIDE THE CRITICAL NONCONTACT (NONRUBBING) SEALS REQUIRED IN THE MARKET SEGMENT WHERE A LONG, MAINTENANCE-FREE OPERATING LIFE IS REQUIRED. THESE EFFORTS ARE BASED ON A WELL ESTABLISHED ANALYTICAL, DESIGN, AND HARDWARE TECHNOLOGYBASE IN THE USE OF FLEXURAL SUPPORTS AS NONCONTACT GAS SEALS IN STIRLING CYCLE EQUIPMENT WITH LIFE POTENTIALS EXCEEDING 20 YEARS. THE FPLA SYSTEM EMPLOYS A LINEAR ELECTRIC MOTOR TO PROVIDE POWER TO DRIVE THE BASIC STIRLING CYCLE AND USES VARIOUS MODULATION TECHNIQUES TO ALLOW THE SYSTEM TO OPERATE IN A DEMAND MODE OVER A WIDE RANGE OF AMBIENT CONDITIONS. THE PHASE I OBJECTIVES ARE (1) TO SELECT A TARGET SIZE FOR THE SYSTEM, (2) TO DEVELOP A DETAILED SET OF SPECIFICATIONS FOR THE PROOF-OF-PRINCIPLE UNIT, (3) TO DEVELOP AND REFINE A CONCEPTUAL DESIGN WITH AN ASSOCIATED DESIGN LAYOUT, AND (4) TO PROJECT THE PERFORMANCE OF THE PROOF-OF-CONCEPT UNIT OVER THE RANGE OF OPERATING CONDITIONS DEVELOPED IN THE SYSTEM SPECIFICATIONS. PHASE II OBJECTIVES ARE TO COMPLETE THE DETAILED DESIGN AND SUBCOMPONENT DRAWINGS, FABRICATE COMPONENTS, ASSEMBLE THE SYSTEM, AND CARRY OUT AN EXTENSIVE TEST PROGRAM THAT WILL EVALUATE BOTH SYSTEM PERFORMANCE CHARACTERISTICS AND HARDWARE DURABILITY ISSUES.