PDF Publication Title:
Text from PDF Page: 041
reactants depending on, among other factors, the dlffusivities of the vario*.s reactant ion specles. For operation i n rhe unmixed-reactant mode these transport processes threaten severe reactmt maintenance difficulties, especially over iong dura- tions. I n the mtxed-reactant mode, however, they are easily accommodated. Either on a scheduled basis or in respo9se to the evceedingof an establ4.hed limit, the cell or systec can be fully dtscharyed and the two reactant volumes completely mixed. I f the reactants have been kept chemically i n balance, ~ n d if both contain adequate bismuth salt, the rodistributton of equal reactant volumes to the resoectivs tankage systems after reblendlng will completely reverse the effects of any net reactant or solvent transport. This process was carried out many times in the laboratory and became a routine part of tl normal operation of cells. F:gure 27 includes polarization data M e n before and after a period of cycling during which the reactants were reblended three cimes. The po1ar:zation curves are unchanged, showing that this treatment, which is made necessary by the mewbrane char(icteristlcs, has no adverse effect on the activity of either cell electrode. The development effort for m~mbranesspecifically for use I n Redo- cells operating at 65" C with mixed reattsnts thus h ~ hsad constderable ;uccess. .' series of cation exchal.ge membranes with low reslstivitles have been developed by two primary suppliers, Ionics, Inc., and the RAI Research Corporation, and evaluated at Lewis. Cells uslr;~these membranes have beell ihown to operats at high e f f i c i e ~ c y ,even a t current denstties approachfng 100 m'!cm2. The mcm- branes are stbtdy and showed no detericratlon while being tested. tiowever, test durations were short, none exceedjng 4 months; l i f e testlng would be an Important requirement for any further development effort. Performance and Cos+ The improvement i n Redox c e l l performance that has rss~St:tj from ;he change to operatSon with mixed reactants at 65" C i s illustrated :.:"able I X. A comparison i s made between a cell operating i n the neg mode and a cell at 25" C with unmlxed reactants. Ezch cell is shown to be operating at a curreqt density typical for Its respective operating mode; eacn ccll is assumed to be in a bipolar stack sc that total rrll reslstlvity is nearly equal to the mem-. brane resistivity. The wost significant difference between the cells is, of course, the five- fold reduction I n membrane resistivity for the new operating mode; Thlc i n turn results in an increase in power density, Cram 29 to 73 mW/cmL, wlth vir- tually no loss i n energy efficiency. For the new operating mode the effect of the hlghe: temperature or, the equilibrium between chromic ion species permits f u l l reactant utilization, com- pared wlth 40 to 50 percent for the 25" C system. ID the light o i this charac- teristic, the argument could be made that, in order for the two systems to have equal capaclty, the 25" C system would require a 100 percent excess of chromlum reactant to allow for the fraction of chromic chloride that was electrocheai- ca:ly inert. Thus the apparent cost penalty for operatiun with mixed reactants would become lnsignlficant. Even disregarding this argument, though, it st111 seems unlikely that the cost of reactants per kilowatt-hour of mlxed-reactantPDF Image | NASA Redox Storage System Development Project
PDF Search Title:
NASA Redox Storage System Development ProjectOriginal File Name Searched:
19850004157.pdfDIY PDF Search: Google It | Yahoo | Bing
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
Heat Pumps CO2 ORC Heat Pump System Platform More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |