• Resources Recycling
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• v.8 no.1
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• pp.23-28
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• 1999

Firing characteristics, transverse rupture strength, and heat capacity were studied of the heat-reservoir refractory materials made of red-firing clay, mill scale, and water glass. The firing shrinkage increased with increase of the clay proportion in samples. The volume of fired bodies showed shrinkage by drying up to $300^{\circ}C$, steady expansion in the 300-$700^{\circ}C$ range due to phase transition of iron oxides. and drastic expansion above $1200^{\circ}C$. Flexural strength decreased from 5.6 Mpa to 2.35 Mpa with the decrease of the ratio of clay to mill scale from 1:1 to 1:3 Heat capacities changed from 1.1 Joul/g$^{\circ}$C to 1.35 Joul/g$^{\circ}$C with the ratio of millscale to clay ratio from 1:1 to 1:3. Mill scale in the specimen appears to exist as liquid phase during firing. Firing the specimens in air leads to the eruption of the molten mill scale to the sample surfaces. Contrarily, firing samples in a refractory sagger with a cover suppressed the eruption of the molten mill scale to the surfaces. The addition of mill scale gave rise to porous sintered bodies which would delay cooling rates of heat-reservoir brick.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.9
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• pp.1085-1094
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• 1992

A variable-spacing cesium thermionic energy conversion test station is designed and fabricated for the study of power generation. The diode is in the form of a guard-ringed plane-parallel geometry in which a polycrystalline rhenium emitter of 2 cmS02T area faces a radiation-cooled polycrystalline rhenium collector of 1.9 cmS02T area. The emission of plasma from heated refractory electrode metal is the driving reaction in the direct conversion of heat to electricity by thermionic energy conversion. The plasma is produced from electrons and positive ions formed simultaneously by thermionic emission and surface ionization of cesium atoms incident on the hot emitter from the cesium vapor in the diode. And high plasma density causes plasma multiplication within the gap due to volume ionization that results in high power output. The variation of the saturation current of a Knudsen converter is investigated at an emitter-collector gap of 0.1 mm and an emitter temperatures. A maximum power output of 13.47 watta/cmS02T is observed at a collector temperature of 963 K and a cesium reservoir temperature of 603 K.