|英文要約||Title: New Energy Venture Business Technology Innovation Program / New Energy Venture Business Technology Innovation Program (wind power generation and other untapped energies ) / Development of Geothermal Energy Utilization System Without Any Power Input by Bubble-Actuated Circulating Heat Pipe (FY2011-FY2012) FY2011 Annual Report
1-1. Outline of Project Bubble-Actuated Circulating Heat Pipe (abbreviated as BACH) can realize both modes of top-heat (upper heated section and lower cooled section) and bottom-heat (lower heated section and upper cooled section), which are changeable by simple valve operations. The purpose of the project is, through applying this BACH technique, to realize air-conditioning auxiliary system of gymnasium without any power input and eco-road system of countermeasure for heat island and snow-melting, utilizing geothermal energy. This project contributes to spreading introduction of geothermal energy as one of renewable energy, and to realizing energy saving society. Within the first year (Phase A), the project aims at confirmation of working of top-heat and bottom-heat changeable BACH, and measurement of the heat transport ability. Experimental parameters are as follows: length of underground heat exchanger section, distance between heated section and intermediate section at top-heat mode BACH, kind of working fluid of BACH, and etc. Field tests are conducted for measuring heat transport ability of BACH under many experimental parameters. 1-2. Progress and Result 1-2-1: Grasp of heat transport characteristics of top-heat and bottom-heat changeable BACH Underground heat exchanger section of BACH works as heated section at bottom-heat mode, and cooled section at top-heat mode. Three types of length of the underground heat exchanger section were used in the experiments; 2m, 4m, and 6m. The distance between heated section and intermediate cooled section at top-heat mode BACH was set to 140mm, which will be changed in the next FY. The working fluid was HFC-134a with void fraction of about 5 %. The kind of working fluid will be changed to alcohol aqueous solution in the next FY. The experimental results show that the tested BACH successfully worked as both modes of bottom-heat and top-heat by simple valve operations. The heat transport ability was about 200 W at bottom-heat mode when temperature of heated section was 8 －C and temperature of cooled section 3 －C. At top-heat mode, the heat transport ability was about 150 W at temperature of heated section 35 －C and temperature of cooled section 9 －C. 1-2-2: Making thermal design tool for the BACH and study on heat exchanger section on the ground surface Thermal design tool for predicting heat transport ability of top-heat and bottom-heat changeable BACH has been developed based on the pre-established physical model with several revisions. This tool will be verified and its development will be completed in the next FY. Preliminary study on schemes of heat exchanger section on the ground was conducted, assuming the industrialization stage of this technique. Some case of low temperature differential operation in summer and winter are simulated using the original calculation schemes. 1-2-3: Settling business plan of this technique In order to examine the specification and price about (a) the air-conditioning auxiliary system for a gymnasium or (b) the snow-melting system for a sidewalk or a parking lot, which are commercial products to be developed in this project, the existing similar products were investigated. 1-2-4: External experts meeting From external experts, several advices for this project were given on Nov.1, 2011.