90 likes | 215 Views
MINIATURE ENGINEERING SYSTEMS GROUP. ECONOMIC ANALYSIS OF VJ LH 2 TRANSFER LINE Presented by K.V.Krishna Murty "Acknowledgement: Mr. Tom Tomsik, NASA GRC for providing sample calculations and also for providing heat leakage rate estimates for VJ lines.".
E N D
MINIATURE ENGINEERING SYSTEMS GROUP ECONOMIC ANALYSIS OF VJ LH2 TRANSFER LINE Presented by K.V.Krishna Murty "Acknowledgement: Mr. Tom Tomsik, NASA GRC for providing samplecalculations and also for providing heat leakage rate estimates for VJlines."
AREAS OF APPLICATION OF RTB CRYOCOOLERS IN VJ LH2 TRANSFER LINE: • In Pre-chilling of metals of inner and outer pipes of the transfer line. • In preventing the In-Line boil-off of LH2 in the transfer line.
IN PRECHILLING OF METALS: • Outer pipe Material – Stainless Steel – Grade 304. • Inner pipe Material – Aluminum. • ASSUMPTIONS & VALUES: • Temperature change = ∆T = 300 – 18 = 282 K • LH2 cost = 2.00$/lb • Metal Mass Basis = 1.0 lb • Input Power to 2 stage RTB cryo cooler = 4243 W • Cooling Power = 50 W • Electricity cost = 0.05$/kW.hr • 2 stage RTB cryo cooler system COP = 0.0117
STAINLESS STEEL CHILLDOWN: • Heat to be removed from the metal/lb = c x ∆T = 11.29 W/lb • LH2 mass requirement to remove 11.27 W/lb = 0.208 lb/hr • LH2 boil-off cost = 0.208 x 2.00 = 0.416 $/hr • Number of RTB’s required = 11.29/Cooling Power of 1 RTB = 11.29/50 = 0.2258 • RTB Input Power Cost = 0.0478 $/hr • Operational cost savings on pre-chilling the outer metal surface material = 88.1%
ALUMINUM CHILLDOWN: • Heat to be removed from the metal/lb = c x ∆T = 21.86 W/lb • LH2 mass requirement to remove 21.86 W/lb = 0.389 lb/hr • LH2 boil-off cost = 0.389 x 2.00 = 0.778 $/hr • Number of RTB’s required = 21.86/Cooling Power of 1 RTB = 21.86/50 = 0.4372 • RTB Input Power Cost = 0.093 $/hr • Operational cost savings on pre-chilling the outer metal surface material = 88.1%
IN MAINTAINING ZERO BOIL-OFF OF LH2 IN THE VJ TRANSFER LINE: • The following cases are considered and compared • Liquid Hydrogen transfer line without cryo-coolers i.e.,letting the liquid hydrogen boil off. • Liquid Hydrogen transfer line with cryo-coolers at regular distances throughout the length i.e.,the case of zero boil off of LH2.
CONCLUSION: • Usage of RTB Cryo-Coolers to cool the LH2 VJ transfer line, mathematically and thermodynamically proves to be highly cost effective with an economic benefit of about 88%. • Note: Only the running cost of cryo-coolers is considered for the entire analysis.