12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaSTUDY ON THE HEAT LOSS REDUCTION METHOD FROM THE SECONDARYPIPELINES IN THE APARTMENT COMPLEXByung-Sik Park 1 , Yong-Eun Kim 2Sung-Hwan Park 1 , Yong-Hoon Im 1 , Hyouck-Ju Kim 1 , Dae-Hun Chung 1, Mo Chung 31 Building Energy Research Center, Korea Institute of Energy Research,102 Gajeong-ro, Yuseong-gu, Daejeon 305-343 KOREA, bspark@kier.re.kr2 Energy System Engineering, University of Science and Technology,113 Gwahangno, Yuseong-gu, Daejeon 305-333 KOREA, rainyday@ust.ac.kr3 Dept. of Mechanical Engineering, Yeungnam University,214-1 Dae-dong Gyeongsan-si Gyeongsangbuk-do 712-749 KOREAABSTRACTThis study aims to suggest better methods for reducingheat losses from the pipelines installed as secondaryheating pipes in the apartment complex in which hotwater is being supplied for space heating and hot waterby a district energy supply company. Right now thedistrict heat supplier is responsible only for the primarydistrict heating pipelines just before the substations inthe apartment complex. That is why the heat lossreduction becomes more important in the secondarypipelines after the substation in the Korean apartmentcomplex.Several methods to reduce the heat loss from thesecondary pipelines were set up and compared by asimulation technique. One of the methods is tocombine the hot water heating pipes and space heatingpipes. Another method is to install a small heatexchanger in each house to supply hot water from thesingle space heating pipeline. In this case we caneasily change the means of heat supply and the rightchoice of end users can be ensured for the means ofheat supply.In this study the preferable method to reduce the heatloss in the secondary pipelines has been suggested.The simulation result has shown about 30% heat lossreduction compared to the existing scheme for thesimple change of methods and much more reductionfor the optimization of pipe diameter and insulationthickness or surface enhancement by low emissivity.INTRODUCTIONKorea is characterized as having four distinct seasons.Apartment complexes became a typical type ofresidence in urban areas after the recent rapidindustrialization of last 30 years. At the moment overhalf of the population chooses to live in apartmentsrather than in individual houses and the trend willincreasingly continue in the future. There are threetypical heating methods for apartment complexes -individual heating, central heating and district heating.At the moment there is a lot of potential for districtheating and cooling. Korea has seen about a 10%supply of DHC among total residential houses which isvery low compared to that of European countries whichsupplies over 50% DHC.If we are to increase green growth with low carbon, it iscrucial to supply DHC, which has higher energyefficiency than any other method, in dense regions ofpopulation. The recent Korean government has showneffort in making a point of energy efficiency throughoutmain energy consuming sectors including buildingarea. However, the supply policy of DHC is now beingcrippled due to various reasons. Makers or consumersof individual heating devices do not have positiveattitudes toward DHC. Therefore it is important to drawattention to the multitude of benefits and merits ofDHC.There is certainly some heat loss from the pipelinesinstalled under the ground to supply the district energyfrom the power plant to the consumers. To reduce theheat loss from these primary pipelines manyinnovations and advancements have been made for along period since the district energy was supplied in thenorthern European countries. The heat loss generallydiffers according to the network type of pipelines. Themore compact that the network is, the less heat lossoccurs. But the type of network cannot be madearbitrarily by the designer. The designer can simplyoptimize the network in view of geological andenvironmental conditions, such as population density,not the type of network. Although heat loss exists withthe primary pipelines, it can be controlled andmaintained effectively by the district heat supplier. Onthe other hand, the heat loss from the secondarypipelines cannot be controlled properly by the buildingowners who are responsible for.The apartment complex is a unique housing system inKorea. It contains many high rise buildings of over 10,often over 20, stories high. In many cases it has over105