Chong-Hyun Cho (Gyeongsang National University, Korea) 팽창과정에서의 터보엑스펜더 영향에 관한연구 Effect of a Turbo Expander for Regeneration in the Expansion Process 2006. 12. 06 Chong-Hyun Cho (Gyeongsang National University, Korea)

Introduction of Laboratory Directe Professor SOO YOUNG CHO A Field of Study Turbomachinery and Energy Conversion Optimization using CFD Micro Rotating Machines Wind Tunnel test Noise and Vibration Measurement Location 403-410, 403-408, 404-203, Wind Tunnel building

Motive Using a turbo expander

Expansion (R134a) Before expansion After expansion Two-phase state

Expander analysis Basic configurations Matching with nozzle exit velocity Tip diameter by the rotational speed Number of blades Decide turbine efficiency Optimum hub diameter (flow quality is changed within the passage) etc. Blade design Impulse blade Internal flow analysis

Experiment (Verneau) an axial type small turbine and single stage nozzle angle was a 74° Parameters Nozzle Rotor Blade height (H:mm) 3.37 3.5 Axial chord (cx:mm) - 12.5 Pitch (s:mm) 7.3 Number of blade (N) 9 72 Mean dia. (Dm:mm) 96.16 Aspect ratio (H/cx) 0.28 Solidity (s/cx) 0.58

Expander Analysis : 50RT Output power : 2.30 kW(heating), 1.81kW(cooling) Torque : 2.50 Nm(heating), 2.46 Nm(cooling) Outer Dia. : 103.3mm Inner Dia. : 67.3mm Partial Admission : 19.96% Rate Rotational Speed : 8763 RPM(heating), 7041 RPM(cooling)

Operating condition : Exp. 9.25RT (DBC 503T-28,000kcal/hr) 50RT model : 1/5-1/6 Size Mass flowrate : 0.25kg/sec Expansion (low RPM) : 11~16bar, 4~6bar Expansion (high RPM) : 16~18bar, 4~7bar

실험장치

Exp. Apparatus

Assumptions : 1-D, homogenous flow Nozzle Design Assumptions : 1-D, homogenous flow Assumptions : nozzle flow isentropic Pressure eq.

Assumptions : Al nozzle, roughness 0.2mm Nozzle Design Assumptions : Al nozzle, roughness 0.2mm Location chock Pressure gradient at chock location

Nozzle Inlet Diameter : 8.0mm Throat Diameter : 3.6mm Exit Diameter : 5.8mm Nozzle Length : 57.8mm

Design of Turbo Expander Supersonic turbine: Min. shockloss Max. utilization factor Impulse turbine

Turbine Design

Turbo Expander

Rotor Specifications Types Parameters A B No. of blades (N) 29 Mean dia. (Dm: mm) 71.85 70.46 Pitch at mean dia. (s : mm) 7.78 7.63 Chord (c: mm) 15.0 Solidity (σ : c/s) 1.93 1.97 Blade height (ht: mm) 11 8 Aspect ratio (ht/c) 0.73 0.53 Blade angle at suction (βs) 65.0° Blade angle at pressure (βp) Blade thickness (t: mm) 4.70 Leading edge thick. (tle: mm) 1.0 Trailing edge thick. (tte: mm)

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Manufacturing EX Enjoy R/C helicopter air show

Summary A turbo expander is installed in the expansion process instead of expansion V/V. It recovered 0.37kJ/kg on the 9.25RT experimental utility. Efficiency increases according to the pressure ratio Efficiency drops linearly 3.7% between shroud and un-shroud rotor Experimental study is very important exact manufacturing of test system Specially, micro rotating machine required manufacturing quality is 0.001mm

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