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, Estonia(a) Gas engine(a) Gas engine(b) Gas turbineFig. 12. Typical pattern of heating load and recoveredwaste heat for CHP prime-moversIt is easy to see the typical consumption pattern ofheating and hot water for residential houses in Koreaas shown in Fig. 12. A large variation of heating load isobserved in heat consumption rate and the optimaldesign of CHP system with such a large variation ismore difficult than with a relatively regular consumptionpattern. The typical annual operation results of therespective CHP prime-movers, gas engine and gasturbine, is also shown in Fig. 12. There is a largedifference in the recovered waste heat prediction forrespective CHP arising from the intrinsic feature for gasturbine, i.e. higher heat to power ratio of gas turbineagainst gas engine.(b) Gas turbineFig. 13. Annual thermal energy supply and demandoperating condition for newly developing area(a) Gas engineFigure 13 shows the annual thermal energy supply anddemand operating conditions for two distinct CHPprime-movers. First of all, the quantity of recoveredwaste heat from CHP is not large enough to cover thewhole heat demand in the winter, so that most of heatdemand is covered by HOB operation on-site. It isnoted that the heat supply from DHC network seldomoccurs during the winter. This is mainly due to the factthat it is also short of heat energy in existing developedareas during the winter. Of course, it is a probablescenario to operate the HOB in existing DHC system toproduce the required amount of heat energy for newlydeveloping area. However, it does not actually happenbecause the operation of the HOB on -site has priorityover that of the HOB in existing DHC system accordingto the operation schemes.162(b) Gas turbineFig. 14. Annual electricity supply and demand operatingcondition for newly developing areaThe thermal network operation is observed to takeplace mainly during the intermediate seasons. It showsthat most of heat demand is covered by the thermalnetworking heat supply and it results in bringing down