Performance analysis of Pluto/Express, multitube AMTEC cells

A review on advances in alkali metal thermal to electric converters (AMTECs)

“…The cell wall facing the BASE tubes should be thicker ($200 mm thick) than the cell wall above the BASE tubes ($100 mm thick) to reduce the parasitic heat losses from the BASE tubes to the side wall [85]. The electrode materials changed from early used TiN with a typical charge exchange current B [20,84,89]. Coat with a high-reflectivity material, such as rhodium (e 5 0.05-0.07) on the artery, the internal circumferential heat shield, and the cell wall above the BASE to reduce parasitic heat losses, increase the cell peak conversion efficiency by 2.1% [84].…”

“…In summary, the design of vapor anode, multitube AMTEC cell have achieved great progress in the last decade, and the efficiency has increased from the initial of $13% [84] to 20-25% [12,85,89]. Figure 3 presents a schematic of a recently developed vapor-fed, liquid anode AMTEC for terrestrial applications [17,18].…”

“…The conical evaporator provides a larger surface area for evaporating the liquid sodium returning from the condenser, as shown in Figure 2(a). The total heat losses and the internal electric power losses must be minimum to get the maximum conversion efficiency without exceeding any temperature and operation limits [84,85]. This implies that:…”

“…The results showed that the higher electric power output and cell conversion efficiency could be obtained by combining materials with geometrical changes for the cell. A number of vapor anode, multi-tube AMTEC cell designs, similar to the PX-series cells have been developed and optimized for improved performance, using an APEAM [1,15,49,[83][84][85][88][89][90]. The main improvements in AMTEC designs are as follows:…”

“…The electrode materials changed from early used TiN with a typical charge exchange current B 5 75 AK 1/2 Pa À1 m À2 and G E 5 50, to the current tungsten/rhodium (Rh 1.5 W) electrodes with a stable charge exchange current B 5 90-110 AK 1/2 Pa À1 m À2 and G E 5 10, which increased the cell's efficiency from 17.3 to 18.8% at a load voltage of 3.5 V [18,19,85]. The thermal radiation shield materials were developed from SS to Ni and then Mo for reduced parasitic heat losses [20,84,89]. Coat with a high-reflectivity material, such as rhodium (e 5 0.05-0.07) on the artery, the internal circumferential heat shield, and the cell wall above the BASE to reduce parasitic heat losses, increase the cell peak conversion efficiency by 2.1% [84].…”