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, EstoniaThe different operation characteristics in terms ofelectricity demand and supply is given in Fig. 25. It isnoted that the electricity demand during the summerincreases considerably as the ratio of absorption typecooling is decreasing. This peak of electricity during thesummer is due to the consumption of electricity foroperating turbo type chillers. From the view point ofdesign of the CHP system configuration in thesimulation, the cooling load is an important parameterto be considered carefully, because the capacity ofCHP system is given in the form of any percentage ofthe peak value of electricity, i.e. the maximum value ofthe annual electricity consumption rate per hour.Therefore, the criteria for defining the CHP capacity isto be varied depending on the amount of cooling loadassigned to turbo type chillers. The respective LNGconsumption patterns depending on the ratio ofabsorption cooling load are compared in Fig. 26. It isinteresting to note that the composition of fuelconsumed by use is substantially changed according tocooling load treatment during the summer. The resultsconfirm that the effects of various aspects ofconfiguration for CHP and cooling system on theprediction of operational parameters (e.g. fuelconsumption rate by use) are properly realized in thesimulation program.By using the simulation approach as presented in thisstudy, the optimal design of the CHP system innetworking operation with DHC system can be carriedout since one can access the detailed physical dataregarding the whole operation of the network systemsuch as annual rate of fuel consumption for respectivesystems (e.g. CHP, HOB, Chiller etc), annualproduction of electricity, heat, and the amount of heatexchange etc. Along with the appropriate coststructures for fuel, product sales (heat and electricity)and the estimation of capital cost, civil construction,and O&M costs etc, one can also make theassessement for the economic feasibility of variousscenarios. However, the detailed economic analysis forthe test cases and the procedures to determine theoptimized CHP system configuration based on it willnot be described in this paper due to the pageconstraints. These ítems will be discussed in furtherstudies.(a) Absorption type 80%166(b) Absorption type 80%Fig. 26. Annual LNG consumption rate by use for differentresponsibility by absorption type coolingCONCLUSIONA simulation program that predicts the energy loads fora mix of buildings and estimate the operationalcharacteristics for networking operation of existingDHC system with CHP system on-site is developed.The distinctive features of this simulation approach canbe summarized as follows,– The unit energy load models are developed foraccurate prediction of energy consumption by useaccroding to any combiation of building type and scale.– A simple mathematical correlation for reflecting thevariations of the network operation on an existing DHCsystem side is newly proposed for the sake of simplicityand efficient simulation process.– The performance data for the commercial products,operation efficiency in a full and part load condition,has been extensively investigated and the databasehas been realized successfully on the simulationprogram.The operational characteristics of thermal networkingoperation has been assessed in terms of systemconfigurations for the CHP and the cooling facility asfollows.– According to the intrinsic features of the CHP primemovers such as gas engine and gas turbine etc, theaspects for the supply of surplus heat is progressing indifferent manners by and large. For a gas engine, theon-site is almost short of heat so that the predictionresults indicate that the additional operation of CHP onthe exisiting DHC system side is induced in theintermediate seasons. Whereas, surplus of waste heatrecovered from gas turbine CHP is supplied toward theexisting DHC system side. As a result, the amount ofelectricity production is being decreases to someextent.– In case of a group of non-residential buildings, theheating load reduces considerably. Therefore, it isprobable that the heating load can be covered by onlythe recovered waste heat from on-site even in thewinter. Due to the heat flow toward the DHC system