The Optimization Of Distribution Pipeline Network In Natural Gas Based Distributed Energy System-smart Grid

The building energy smart grid based on natural gas based distributedenergy system is proposed in this paper, in order to tackle with theincoherence between energy supply and energy utilization components innatural gas based distributed energy system, which results in a low totalenergy efficiency. This paper emphasizes on the optimization of distributionpipeline to offer a guide and basis for the optimal design of NDES-SGsystem.First, based on the First Thermodynamic Law, research on insulationthickness optimization is conducted, a critical factor affecting the energyloss in cooling and heat transmission and distribution pipeline network.And the constraint condition of maximum cooling loss is proposed, to studythe synergic relation between the insulation layer thickness and distributiondistance, and the economic characteristics of transmission and distributionnetwork with different insulation materials. From the calculation resultsand analysis of a project case, it is shown that an optimal synergic relationbetween insulation layer thickness and transmission distance exists, whichmeans an inflection point can be determined. The optimal distributiondistance is in the range of1.1km~2km under various supply capacity andtemperature differences.Second, this paper aims to quantify the energy degradation and analyzethe key factors influencing the exergy loss due to heat dissipation in theheating pipe network from the aspect of the second thermodynamics law.Moreover, the optimal exergy economics and the maximum heat loss rateare taken as the principle to determine the optimal insulation layerthickness and transmission distance.A small-scale building complex consisting of five buildings located ona compus in Changsha is taken as the project case, for the optimal design ofthe cooling and heating distribution pipeline system on the basis ofthermoeconomic. Air conditioning operation hours is obtained through BINmethod. According to the existing geograghical coordinates of the fivebuildings, available energy station options and pipelines, a preliminary layout is devised. Then the objective function and constraint conditions areoutlined to get the design parameters and optimal energy station locations.