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Energy Conversion Systems B. V., a joint venture of ADENCO advanced energy conversion in the Netherlands and the Institute of Physics and Power Engineering (IPPE) in Russia is making good progress in the commercialization of terrestrial thermionics. A survey is given of recent results, including the design of a prototype TECTEM®. This is a central heating facility equipped with thermionic converters. This prototype will serve as a test vehicle for various TECTEM concepts. The TECTEM consists of an array of Thermionic Energy Converters (TEC's), each equipped with it's own radiative burner recuperator, a boiler and an invertor which converts the low voltage DC electricity into 220 V/50 Hz AC electricity. Some preliminary test results of combustion heated TEC's are presented, as well as some data about improved performance of TEC's with modified electrodes as compared to the standard Mo-Ni electrode pair.

A TECTEM is a thermionic energy module. It will ultimately replace the central heating facilities annex domestic hot water systems in homes. It's merit stems from the fact that in conventional central heating facilities, high temperature heat is being used for low temperature purposes, In a TECTEM, some of this heat is used to generate electricity. The waste heat of the Thermionic Energy Converter (TEC) can still be used for producing domestic hot water and for heating a house. Because of this the marginal efficiency, with which electricity can be generated, can be as high as 80%. The specific electricity costs are rather low. Since the TECTEM saves energy as compared to electricity production by central station power plants, it also reduces CO2 emission. A brief overview is given of the design criteria leading to the design of the first TECTEM. The design of this prototype incorporating six TEC's is explained.

Thermionic cogeneration is developing as a new energy conservation option. The characteristics of thermionic systems using combustion of natural gas as heat source are studied. The - until now unused - high temperature potential of fuels can be applied in order to extract work using the high temperature thermionic conversion process. The high temperature of the emitter and the required large heat flux to it demand a high radiation temperature of the burner walls. As natural gas can only just reach these requirements the resulting system efficiency drops to an intolerable low level if the combustion air is not preheated and the heat from the flue gasses is not recuperated. An analytical study shows the effects of using the collector cooling air to preheat the combustion air and the influence of the heat exchanging capacities of the recuperator and the burner walls.