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Research paper : Demonstration test of energy conservation of central air conditioning system at the Sapporo City Office Building (H. Takeuchi )−141−Synthesiology - English edition Vol.4 No.3 (2012) and the value obtained from the temperature difference measured at the inlet and outlet of the heat exchanger were compared, and the measurement value was about 13 % lower. In general, it is said that the reduction of heat transfer performance is greater than the flow drag reduction. In the test, the flow drag reduction for the entire building was 47 %, and about 13 % reduction in the heat transfer coefficient indicated that the heat transfer performance reduction in the heat exchanger tube was not that great. Also, the outlet temperature of the refrigerator remained at 11 °C, the set value for operation during summer, and it became clear that the energy conservation by flow drag reduction did not cause any problems for operation of the air conditioner. 6.3 Maintenance of long-term stabilityAfter the injection of the agent, it is necessary to maintain the appropriate agent concentration. The primary reason why the concentration decreases is the leakage of the circulating water containing the agent. If there is small but regular leakage from the joints such as from the packing, relatively large amount of water may escape during the channel switching from summer to winter. The accumulation of air in the channel is prevented by adding freshwater, but the agent concentration may decrease and the flow drag reduction effect may be reduced in this maneuver. The total amount of freshwater added must be measured, and extra injection of the agent is necessary if significant reduction in agent concentration occurs. In case of the Sapporo City Office, there was no leakage from the joints, but there were several tons of outflow when switching the channel from the summer absorption refrigerator to winter heat exchanger. Therefore, after switching, the surfactant concentration was measured, and additional injection was done based on the measurements. With accumulated experience, measures could be taken in the switching maneuver, and the work could be accomplished with very little outflow. As a result, currently extra addition of the agent may or may not be needed. The measurement of the surfactant concentration is done twice a year after switching the cooling/heating. Although the concentration can be estimated indirectly on site from the electric conductivity of the sampled water using the calibration curve, the concentration of the agent is measured directly along with the concentrations of the iron, copper, and other substances by subcontracted analysis.The pipes were replaced from iron to stainless in 2001 due to rusting caused by aging. However, the heat exchanger is iron and the fan coil in each room is copper, and electric corrosion may occur. About 1600 days have passed since the agent had been introduced, but the concentration of iron and copper in the circulating water is stable, and it is determined that there is no corrosion in the pipe system.The long-term stability of the agent is expected to be affected by the interaction of the agent and the substances that were already present in the circulating water, the expiration of effectiveness due to the temperature history, and the lifespan of the agent itself. Although the instability that may occur in a short time can be seen before injection, the long-term effect must be determined from the past case studies. However, the follow-up surveys of past injections have not been disclosed. Therefore, this case in which the effect has been sustained for over 1600 days is a valuable demonstration.For the toxicity of the agent, material safety data sheet (MSDS) has been created, and there is no problem as long as the agent is processed through the wastewater processing plant, without direct release to the rivers. 7 Effect of technology diffusion promotionFigure 6 shows the changes in the number of inquiries to Company L, the developer of the flow drag reduction agent, after the three press releases.The number of inquiries increased after AIST conducted a press release[10] in May for the heating period test results in February 2007. Also, the test results for the cooling period for 2008 were announced at the Sapporo City Office, but there were no significant increase in inquiries, perhaps because the releases were mainly in local newspapers. The inquiries increased dramatically when Japan Broadcasting Corporation (NHK) aired the news in January 2009[11].The places where the surfactant was actually installed in two years are shown in Fig. 6. There were 18 cases, including 9 cases, the highest number, in private company factories, 4 airport facilities, 3 public facilities, and 2 private buildings. According to Company L, the number of installations increased clearly after the public announcement of the demonstration test by AIST. Until then, even if Company L installed the agent to a private facility and publicized the energy saving effect, it was mostly seen as an advertisement of the technology by a private company. However, the news coverage of a public research institute such as AIST demonstrating Fig. 6 Changes in the number of inquiries to Company LNumber of inquiries01020304050Jan, 2007Feb.Mar.Apr.May, 2007Jun.Jul.Aug.Sept.Oct.Nov.Dec.Jan, 2008Feb.Mar.Apr.May.Jun.Jul.Aug.Sept.Oct.Nov.Dec.Jan, 2009Winter testSummer testMay 28, 2007: Press release by AISTNovember 2, 2007: Press release by Sapporo CityJanuary 4, 2008: Nationwide broadcast “Good Morning Japan” by NHK

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