• Transactions of the Korean hydrogen and new energy society
• /
• v.31 no.2
• /
• pp.169-176
• /
• 2020

There is a growing interest in hydrogen energy utilization since an alternative energy development has been demanded due to the depletion of fossil fuels. Hydrogen is produced by the reforming reaction of natural gas and biogas, and the electrolysis of water. An solid oxide electrolyte cell (SOEC) is reversible system that generates hydrogen by electrolyzing the superheated steam or producing the electricity from a fuel cell by hydrogen. If the water can be converted into steam by waste heat from other processes it is more efficient for high-temperature electrolysis to convert steam directly. The reasons are based upon the more favorable thermodynamic and electrochemical kinetic conditions for the reaction. In the present study, steam at over 180℃ and 3.4 bars generated from a boiler were converted into superheated steam at over 700℃ and 3 bars using a cylindrical steam superheater as well as the waste heat of the exhaust gas at 900℃ from a solid refuse fuel combustor. Superheated steam at over 700℃ was then supplied to a high-temperature SOEC to increase the hydrogen production efficiency of water electrolysis. Computational fluid dynamics (CFD) analysis was conducted on the effects of the number of 90° elbow connector for piping, insulation types and insulation layers of pipe on the exit temperature using a commercial Fluent simulator. For two pre-heater injection method of steam inlet and ceramic wool insulation of 100 mm thickness, the highest inlet temperature of SOEC was 744℃ at 5.9 bar.

• Journal of Korean Society for Quality Management
• /
• v.47 no.3
• /
• pp.425-435
• /
• 2019

Purpose: The purpose of this study was to resolve the Naval ship's Local Operation Panel(LOP) malfunction problems which caused by overheating in summer season and dispatching to equatorial regions. Methods: Instead of using dual type heat insulation materials(consist with ceramic wool and glass wool), aerogel heat insulation materials were used for decreasing heat emissions from gas-turbine heat waste steam pipes passing water-jet- room. Experiment and Computational analysis of heat flow were conducted to analyze the internal room temperature changes. Results: The results of this study are as follows; The aerogel heat insulation materials suppress heat emission more efficiently than dual type insulation materials. The cold surface temperature of insulation was far more decreased and internal room, LOP surface temperature also showed significant results too. Conclusion: The substituted heat insulation materials appeared remarkable performance in decreasing room temperature that it could be used for suppressing the LOP overheatings and malfunctions.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.813-816
• /
• 2009

A commercial-scale RDF boiler that its burning capacity is 400 kg-RDF/hr and steam production capacity is 2 ton/hr. It has a chain type stoker and waste heat recovery system. Heat exchanger is vertical water-pipe so that soot blowing and removal is convenient during operation. Dry scrubber, bag filter and activated carbon tower have been installed for the reduction of air pollutant gases and dust. Analysing data of pollutants from stack such as $SO_x$. $NO_x$ and dioxin shows so good results that the boiler system could comply the regulated emission limits.

• Transactions of the Korean hydrogen and new energy society
• /
• v.10 no.1
• /
• pp.41-48
• /
• 1999

The heat transportation from a complex of industry to a rural area needs more efficient method because the distance between them is usually more than 10km. Conventional heat transportation using steam or hot water via pipe line has limits in transportation distance (about 3-5 km) because of the heat loss and frictional loss in the pipe line. Metal hydride can absorb or discharge hydrogen through exothermic and endothermic reaction. After releasing hydrogen from metal hydride with heatings by waste heat from industry we can transport this hydrogen to the rural area via pipe line. In the urban areas other metal hydride reacts with this hydrogen and produces heat for heating. Cool heat is also obtained if it is possible to use metal hydride with low reaction temperature. So metal hydride can be used as a media for transportation, storage of heat. Some problems of the heat transportation using metal hydrides, and the example of heat transportation system were discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.10 no.6
• /
• pp.773-783
• /
• 1998

The heating system for apartment complex may be classified as old systems including central system with steam boiler(S1), gas engine driven heat pump system(S2), system using waste heat(S3) and new systems including mechanical vapor re-compression system with flashing heat exchangers(S4), system using methanol(S5), system using metal hydride (S6). The purpose of the present study is to suggest optimal heating system by technically, economically and environmentally evaluating old and new heating systems of apartment complex from 500 to 3,000 households. Economic evaluation based on the technical evaluation results which estimated heat transfer area of heat exchangers and capacity of equipments was estimated initial investment cost, annual operating cost and relative payback period by considering annual increasing rates of energy cost and interest. Environmental evaluation provided annual generation rate of carbon dioxide. Initial investment cost was cheap in the order of S6, S5, S3, S2, S4, S1, annual operating cost was cheap in the order of S1, S2, S4, S5 and relative payback period was short in the order of S6, S5, S2, S3 and S4. Relative payback period was within 8 years for all scenarios of 3,000 households, and was increased as annual increasing rates of energy cost and interest were increased. As transportation pipe length was increased twice, payback period was increased by 1.4~2.6 time. The effect of temperatures of waste gas and waste water on the relative payback period was small within 0.8 years. The annual generation rate of carbon dioxide was big in the order of S4, S2 and S1. S4 was the most economic system among whole scenarios when S1 was replaced with other scenarios.

• Transactions of the Korean hydrogen and new energy society
• /
• v.11 no.1
• /
• pp.43-49
• /
• 2000

The heat transportation from a complex of industry to a rural area needs more efficient method because the distance between them is usually more than 10km. Conventional heat transportation using steam or hot water via pipe line has limits in transportation distance (about 3~5 km) because of the heat loss and frictional loss in the pipe line. Metal hydride can absorb or discharge hydrogen through exothermic or endothermic reaction. After releasing hydrogen from metal hydride by means of the waste heat from industry, we can transport this hydrogen to urban area via pipe line. In urban areas, other metal alloy reacts with this hydrogen to form metal hydride and produces heat for heating. Cool heat is also obtained if it is possible to use metal hydride with low reaction temperature. Therefore, metal hydride can be used as a media for transportation and storage of heat. $MmNi_{4.5}Al_{0.5}Zr_{0.003}$, $LaNi_5$, $Zr_{0.9}Ti_{0.1}Cr_{0.6}Fe_{1.4}$, $MmNi_{4.7}Al_{0.1}Fe_{0.1}V_{0.1}$ alloys were selected for this purpose and the properties of those metal hydrides were discussed. The design and control techniques were proposed and discussed for this heat transportation system using metal hydride.