AN EXPERIMENTAL STUDY OF POWER GENERATION SYSTEM USING HEAT OF CHEMICAL DECOMPOSITION OF NITROUS OXIDE

摘要

These days, the planets in the solar system are explored actively with various spacecraft. In the explorationdistant from the sun, there are two problems. One is a power supply drop of solar cells. The other is a lowtemperatureenvironment. Hence, low melting-point propellants are required in order to decrease the powerconsumption of propellant heaters. The freezing-point of nitrous oxide is 183 K under ordinary pressure. Hence it issuited for the space exploration. Moreover, its decomposition heat, which is 82 kJ/molN_2O, can convert to electricpower with thermoelectric modules. Hence, this power might be used for electric devices on-board.In order to generate electricity from the heat, thermoelectric modules were selected because they were simplestructure and had no mechanical moving parts. N_2O decomposition makes two levels of temperatures, which create ahot and a cold side. These represent N_2O decomposed gas and N_2O gas respectively. Therefore, electricity can begenerated by sandwiching the thermoelectric modules between these two thermal sources. This is the concept of thepower generation system.Because this is a new field of study, at first the characteristic features of the power generation system should beapprehended. In this paper, the effect of N_2O mass flow rate on open-circuit voltage was investigated in adiabaticmodel of the power generation system. After we obtained the experimental data, we compared theoretical opencircuitvoltage with the experimental one.In conclusion, the theoretical voltages were about five times as large as the experimental voltages. Therefore, wechanged the model into a non-adiabatic model. As a result, theoretical open-circuit voltage was 70-93% ofexperimental one in the range of the mass flow rates, 0.10g/s to 0.19g/s. This conclusion shows that the nonadiabaticmodel is effective in prediction of open-circuit voltage.