AAE 450 – Spacecraft Design Sam Rodkey 1 Active Thermal Control Design Sam Rodkey March 1 st, 2005 Project Management Project Manager

AAE 450 – Spacecraft Design Sam Rodkey 2 Proposed MHV Radiator System 2 m 10 m 0.25 m 0.1 m 0.25 m 0.4 m Average Radiator Surface Temp: 340 K Radiator Emitting Area: 20 m 2 Radiator Total Volume: 2 m 3 Compressor Volume: m 3 Coolant Anaylzed: Ammonia

AAE 450 – Spacecraft Design Sam Rodkey 3 MHVActive Thermal Control System Estimated Mass: 1500 kg (reduced by 25%) Pressure Ratio: 3.5 (5.92 bars, 20 bars) Interplanetary Transit Performance Max Heat Removed: 16.8 kW Max Power Consumption: 2.8 kW Maximum Evaporator Temperature: 282 K Mars Surface Performance (Atmospheric Temp = 300K) Max Heat Removed: ~150 kW Max Power Consumption: 26 kW Maximum Evaporator Temperature: 282 K  Need to further characterize convection correlations, performance estimates numbers seem a bit higher than expected

AAE 450 – Spacecraft Design Sam Rodkey 4 Script Additions  Improved EES Script for use in any future active thermal control system for any vehicle and heat loading  More accurately estimated temperature drops across heating pipe surfaces and due to free convection.  Developed ability to vary the dimensioning and configuration of the radiator pipes in order to optimize the design (diameter, thickness, conductivity, density, etc.)  Changed coolant used in analysis to pressurized saturated ammonia liquid/gas mixture.

AAE 450 – Spacecraft Design Sam Rodkey 5 Desired Improvements for Script  Need to model the pressure drop across the radiator pipe, since it will have significant length and frictional losses at high pressure ratios and mass flow rates.  More accurately estimate overall compressor requirements and total coolant masses.  Try to use more accurate free convection correlations or forced convection correlations (implement Churchill and Chu Relation for cylinders in cross-flow, or other empirical relation )

AAE 450 – Spacecraft Design Sam Rodkey 6 Convection/Radiation Case Properties A_eff is less than the design area, which means we can achieve greater than the required heat transfer for this case.

AAE 450 – Spacecraft Design Sam Rodkey 7 Radiation Only Case Properties

AAE 450 – Spacecraft Design Sam Rodkey 8 Cycle Diagram