1. MINIATURE JOULE-THOMSON CRYOCOOLERS FOR PROPELLENT MANAGEMENT
MINIATURE ENGINEERING SYSTEMS GROUP
MINIATURE JOULE-THOMSON CRYOCOOLERS FOR PROPELLENT MANAGEMENT
TASK I: Thermodynamic Cycle Analysis and System Optimization
Presented by 
K.V.Krishna Murty
MMAE

2. Schematic Layout of the Flow Setup and the proposed Cryogenic System
[1: proposed cryo cold head, 2: common compressor for the JT cryogenic system, 3: common heat exchanger for external heat rejection, 4: recuperative heat exchanger for regeneration, 5: JT expansion valve – this would be located physically next to item 6, 6: cold head heat exchanger, 7: vacuum jacket, dark arrows indicate flow of neon, open arrows indicate flow of LN2]

3. JT Cryocooling System External HX Cold head JT expander Load Interface
Recuperator
Motor and Compressor
Qrej
JT expander
Load Interface
External HX
Cold head

4. Schematic representation of Joule-Thomson Cycle with respect to the current system

5. Specifications Compressor: Pressure Ratio = 10, Efficiency = 85%,
Working Fluid = Neon, Operating pressure range = 3 bar to 30 bar,
Electric Power required to run the motor for compressor = 12 kW.
Recuperative Heat Exchanger:
Temperature drop/rise = 227 K,
Pressure difference between Hot side and Cold side = 27 bar.
JT Valve:
JT coefficient = 0.259, Temperature drop across JT Valve = 7 K.
Heat Sink:
Heat Load = 2196 W, Working pressure = 30 bar.
Cold Head:
Cooling power = 20 W, Working pressure = 3 bar.
Overall system:
Working Fluid = Neon, Working pressure range = 3 bar to 30 bar,
Mass flow rate/cold head = g/s,
System COP =

7. Selection of JT coefficient

8. Other considerations and Optimization

9. Other considerations and Optimization
Lowering of the inlet temperature to the compressor from 300 K to 280 K  No use. Instead it lowers the COP value.
Increasing Pressure Ratio to 70 (operating pressure range of 1 bar to 70 bar)  Improves COP and JT coefficient. But the option is discarded owing to the difficulty in designing the miniature heat exchanger for a pressure difference of 69 bar.

10. Companies contacted for purchase of off-the-shelf Compressor and JT Valve
Fluitron, Inc. – negotiation in active progress.
RIX Industries – negotiation in active progress.
Sundyne Corp.,
Gas Equipment Engg. Corp.(GEECO),
Burton Corblin, Inc.
ProcessFlo, Inc.
Hydro-Pac Inc. – negotiation in active progress.
CPC-Cryolab(tm) – negotiation in active progress.

11. Future Work To accomplish Task II:
Development and Fabrication of a Highly Effective, Compact Recuperative Heat Exchanger.
NOTE: Cycle specifications are optimized based on the fact that LN2 test bed would be used for conducting the experiment.