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

1. 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 , , , Wind Tunnel building

2. Motive
Using a turbo expander

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

4. 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

5. 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

6. 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)

7. 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

8. 실험장치

9. Exp. Apparatus

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

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

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

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

14. Turbine Design

15. Turbo Expander

16. 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)

17. Manufacturing EX

18. Manufacturing EX

19. Manufacturing EX

20. Manufacturing EX

21. Manufacturing EX

22. Manufacturing EX

23. Manufacturing EX Enjoy R/C helicopter air show

24. 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

25. Thank you for your attentions