Vol.4 No.3 2012

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Research paper : Demonstration test of energy conservation of central air conditioning system at the Sapporo City Office Building (H. Takeuchi )−139−Synthesiology - English edition Vol.4 No.3 (2012) completed in 1971. It has two-tier basement, 19 aboveground floors, and a total floor area of 42,000 m2. It is designated as a “type 2 designated energy management factory”Note ) .Figure 5 shows the cooling/heating water circulation system of the building. The circulating water is ejected from the 37 kW circulating pumps installed in the machine room on the 2nd basement for summer and winter. The water is sent to the expansion tank on the 19th floor via four 5.5 kW and one 3.7 kW or a total of five booster pumps located in the air conditioning equipment room on the 8th floor, and it is returned to the 2nd basement. The water circulated is 32 tons.Individual air conditioning is not installed in each room. Since the test involved using the system common to the office building that would be used for daily work, it was impossible to operate or shutdown the system for the purpose of this test. Due to this situation, unlike the test in the lab, it was difficult to freely change the parameters, and the experiment had to stop immediately in times of emergency and the original condition restored. Therefore, five parties became in charge of their respective roles: Shunan Regional Industry Promotion Center, which had been involved in the development of the agent and therefore had full knowledge of the agent property, had experience in various cases as it was involved in the injection at several facilities; AIST and Tokyo University of Science (TUS) which had the abilities to conduct basic research as well as to project or clarify the transitional changes of flow and heat transfer phenomena of the circulating water after agent injection; Fujiwara Environmental Sciences Institute Ltd. which had expertise in measurements of flow rate, temperature and electric energy in a cooling/heating system composed of complex pipes; and Sapporo City Office which had mechanical and electrical engineers who were knowledgeable of the entire system and would engage in maintenance and management after the injection. 5 Preparation of the demonstration test5.1 Basic understanding of the flow propertyThe agent showed flow drag reduction effect at 5~65 °C, so it could be used continuously throughout the summer period when cold water was circulated and in the winter period when heated water was used. However, there was a temperature dependency of the flow drag reduction effect, and it was necessary to study the values from 7 °C to 45 °C that was the actual usage range. It was also useful to understand the effect of the rust inhibitor used concurrently on the reduction effect. These were measured using the water circulation experiment apparatus of the Tokyo University of Science. The test section had channel length of 1 m and internal diameter of 10.7 mm. The agent concentration was varied between 3000~6000 ppm, to measure the flow rate dependency of the flow drag reduction effect[7].In using the surfactant on site, there were cases when it could not be used due to bubbling. For example, the expansion tank might be open to the atmosphere and air might be regularly introduced in some areas. For the identification of complexities in the channel, the staff of the control room of the City Office in charge of the daily system maintenance did a preliminary check of the problem areas.The power consumption of the pump and the flow rate in each pump channel were measured before the agent injection. Portable transit time ultrasound flow meter was used for flow rate measurement, and the feeder power recorder was used to measure the power. 5.2 Inverter installationAs the flow drag decreased by agent injection, the amount of circulating water would surpass the rated flow. By decreasing the revolution of the circulation pump using the inverter, this would be brought back to the rated flow. As a result, the power consumption of the pump would decrease, and energy savings would become possible. Therefore, the installation of an inverter was necessary for this technology. From the results of the preliminary flow property tests and flow rate measurement, it could be determined that sufficient circulation would be obtained after the agent injection even when the operation of the five booster pumps on the 8th floor is stopped. The inverters were installed in each of the 37 kW winter and summer circulation pumps. The harmonics outflow current that might affect other devices was measured, but it was found that countermeasures were unnecessary. Fig. 5 Diagram of the cooling/heating system water circulation of the Sapporo City OfficeExpansion tankWinter useBooster pump5.5 kW x 4 pumps3.7 kW x 1 pumpAbsorption refrigerator2nd basementInverter37 kWHeat exchanger8th ~19th floorsFan coil unit air conditionerInverter37 kWMetering pumpRegional heat supplyRegional heat supplySurfactantSummer use

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