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 )−137−Synthesiology - English edition Vol.4 No.3 (2012) and to consider how much it can contribute to the energy conservation in air conditioning systems of buildings. Therefore, we collaborated with the City of Sapporo and applied this technology to the cooling/heating water circulation system of the office building, conducted a demonstration test for energy savings, and attempted to diffuse this technology further by publishing the results.In this paper, we look at the technology that was introduced in only a limited number of facilities because the research stopped at the basic phase or because the data was not disclosed even though the effectiveness was demonstrated. We gathered specialists of the component fields of the technology, and these specialists assumed their respective roles according to the technology integration scenario. The demonstration test was conducted in the Sapporo City Office Building that was in full operation. The results will be discussed here. 2 ScenarioFirst, the Toms effect will be briefly explained. In 1949, Toms showed that it was possible to reduce the pressure loss of the turbulent flow in a pipe by adding a small amount, about 5 to 10 ppm, of long-chained polymer to the water flowing inside the pipe[2]. The effect is temporary since the polymer structure is destroyed by the shear force of the flow and the structure is not reconstructed. On the other hand, when a surfactant is used instead of the polymer, the micellar structure formed is repeatedly reconstructed and the effect is sustained. As shown in Fig. 1, with the increased concentration of the surfactant, the monomers aggregate to form a spherical and then rod-like micelle. When these rod-shaped micelles form a three-dimensional micelle network structure, the turbulence of the flow is inhibited and the flow drag is reduced. Fig. 2 shows the velocity vector distribution of the channel flow[3]. Fig. 2a shows the case of water only, and Fig. 2b shows the case when the surfactant is added. By adding the surfactant, the irregular eddies in the flow disappear, and regular flow is achieved. This structure is broken in areas such as pumps, valves, elbows, or any parts where the flow path is greatly disturbed, but is reconstructed in relatively straight sections of the pipe, and contributes to the reduction of flow drag. When cooling and heating large buildings by circulating cold or hot water, large amount of electric power must be used to operate the water circulation pump. To drastically reduce this energy, it is effective to apply the Toms effect where the flow drag is decreased by injecting the surfactant in the circulating water. The principle of energy conservation using this method is as follows: the circulating water that surpasses the rated flow can flow through when the flow drag is reduced by adding the surfactant; the revolution of the circulation pump is lowered using the inverter to regain the rated flow; and the power consumption of the pump decreases, thus achieving energy conservations.As shown in Fig. 3, one of the elemental technologies is to design and create an agent to see which type of surfactant matches this purpose. Another element is to clarify what kind of fluid dynamics and heat transfer occur in the water with added agent in the circulation channel and make explicit the energy conservation effect. Also, it is necessary to study the long-term stability of the added surfactant, the duration of the energy saving effect, and the maintenance procedure to operate and sustain this energy conservation technology.Fig.1 Changes in micelle formation due to concentration changeFig. 2 Changes in flow due to micelle networkSurfactant concentrationLowRod-like micelleSpherical micelleSurfactant single-moleculeHydrophobic groupHydrophilic groupHighDirection of flowDirection of flow(b) Flow after adding surfactant(a) Flow of water only05101520253035404550403020100X mmY mmWater: Re=1.77×1040.000.080.170.250.340.42U m/sVector: Galilean decomposition ( -0.9 0 , ), Contour: UUUV05101520253035404550403020100X mmY mmCTAC25 ppm(30℃, DR=58 %): Re=1.35×1040.000.070.140.220.290.36U m/sVector: Galilean decomposition ( -1.03 0 , ), Contour: UUUVFig. 3 Scenario for energy savings using surfactant in air conditioning of buildingsDramatic energy conservation for building air-conditioningMethodology systemKnowledge systemCreation of surfactantToms effectCenterAIST TUSInvestigation of inner-pipe heat and flow phenomenaObservation, investigationSynthesis, integrationObtainment of long-term stabilityMaintenance of heat transfer performanceAppearance of flow performanceCompany TUSAISTSapporo City CenterDemonstration at Sapporo City OfficeDivision of role in joint researchPrevious researches ComponentsTotal scenarioResearch objective

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