12th International Symposium on District Heating and Cooling

is covered by operating HOB. In other words, only theoperation of HOB on the DHC system side is affectedby the thermal networking operation in winter. Asshown in Fig. 20 (b) and Fig. 21, the production ofelectricity on the existing DHC system side during theintermediate seasons is certainly decreasing due to thesupply of surplus heat from CHP on-site, which resultsin the diminution of the rate of operation for the CHP onthe existing DHC system side.The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, Estonia(a) Absorption type 80%Fig. 22. Heat balance of operating the absorption chillersThe operating characteristics for cooling load aredescribed in the following with Fig. 22. It shows theheat balance of operating the absorption chillers. Thecooling load exceeding the supply capacity fromrecovered waste heat is modelled to be covered byproviding auxiliary heat for absorption chillers by directgas combustion. The cooling load assigned to turbotype chillers is dealt with as an electricity loadconverted according to the COP of the correspondingproduct of turbo chillers.(b) Absorption type 20%Fig. 24. Heat balance of operating the absorption chillersfor different responsibility by absorption type coolingThe heat balance of absorption chillers for differentratio of responsibility by absorption type cooling isshown in Fig. 24. In case of 80% absorption typecooling, the recovered waste heat is not sufficientenough to handle the assigned cooling load, so anauxiliary heat source, such as direct gas combustion, isneeded to cope with the full absorption cooling load.Whereas, when the 20% absorption type cooling loadis concerned, the required amount of heat for theabsorption chillers can be supplied only by therecovered waste heat as shown in Fig. 24. Theremainder of total cooling load is covered by turbo typecooling system.Fig. 23. Annual LNG consumption rate by use for newlydeveloping area of a grope of non-residential buildingsThe LNG consumption with the cooling load for newlydeveloping area is predicted as shown in Fig. 23. Dueto the lower level of heating loads for non-residentialbuildings, operation of HOB facility is only permissiblein a limited period even in the winter. It is also notedthat a portion of LNG is consumed to provide auxiliaryheat for absorption chillers by direct gas combustion incase of shortage of heat from recovered waste heat.The effects of cooling system configuration on thenetwork operation characteristics are assessed in detailas follows:(a) Absorption type 80%(b) Absorption type 20%Fig. 25. Annual electricity supply and demand operatingcondition for newly developing area for differentresponsibility by absorption type cooling165