Modelling Of District Heating And Cooling Demand And Analysis On Supply Options In The Context Of Carbon Neutrality

In the context of "carbon neutrality",the construction business is facing significant pressure to lower its emissions to meet national emissions reduction targets.It accounts for45.35% of the total national energy consumption.Thus,it is crucial to intensify the promotion and adoption of diverse energy-saving and environmentally-friendly theories and technologies to effectively curtail energy consumption and carbon emissions.With the continuous development of renewable energy sources and the upgrading of their application technologies,the application trend of district energy systems is gaining momentum.District energy systems will be an important development for the future energy supply of buildings.This paper provides insights into how to integrate energy-efficient building operations with the “carbon neutrality” target at different time points,as well as the applicability of different cooling and heating sources across the country.The research results will contribute to the promotion,design,and application of district energy systems.The main research content and achievements of this article are as follows:(1)Establishment of a model for analyzing heating and cooling demand within a region.The model takes the load limits of a district or city as its target and incorporates urban meteorological parameters,energy efficiency standards of buildings and urban planning standards.Meanwhile,the calculation of national heating and cooling demand is achieved by using the degree-day method and the load inversion method.In addition,the model can also perform relevant load calculations for buildings in a specified area that have both heating and cooling demands.The established regional heating and cooling demand model can calculate the energy-saving level that all buildings in the region should achieve through energy-saving measures under different node targets,and the calculated daily load of buildings can provide a basis for real-time energy supply system regulation.(2)Analysis of the heating and cooling load characteristics of urban areas.Ten cities were selected from the five building thermal design regions in the country for the corresponding load calculation.Firstly,taking one of the cities as an example,the load variation patterns of various types of buildings in the city during the energy supply period were analyzed.Then,the calculation results of the ten selected cities were compared and analyzed to obtain the energy consumption characteristics of different building thermal design regions.Finally,the load characteristics of buildings in urban areas that have both heating and cooling demands were analyzed.The calculation results show that the unit area load of various types of buildings in urban areas is mainly influenced by the set load limit,and the total proportion of load throughout the year for each type of building is mainly affected by the corresponding building area.In different building thermal design regions,the heating load and cooling load are mainly affected by the outdoor calculated temperature.The lower the outdoor calculated temperature in winter,the higher the heating load,while the higher the outdoor calculated temperature in summer,the higher the cooling load.(3)National distribution of heating and cooling loads and supply pattern divisions.Organized and summarized the load calculation results of 170 counties and cities.And using the data,distribution cloud atlases were drawn within the national boundary of China for the unit area heating load,cooling load,and the ratio between the two loads(i.e.,heating-cooling ratio)throughout the year.The overall distribution trend of the heating load decreases gradually from north to south.The cooling load gradually increases from north to south within the longitude range of 104° to the easternmost part of China,and gradually decreases from the Turpan region to both sides in the latitude direction within the range below 104°.Based on the distribution cloud atlas of the heating-cooling ratio,the applicable scope of heating and cooling equipment can be divided within the national boundary.For areas with a heating-cooling ratio greater than 10,it is recommended to consider centralized heating in winter and decentralized cooling in summer.If there is no centralized heating in winter,heating with heat pumps can be considered.For areas with a heating-cooling ratio of around1.5,it is recommended to consider using heat pumps for winter heating and summer cooling.For areas with a heating-cooling ratio of around 0.1,it is recommended to consider using a separate cooling mode in summer,such as using various types of electric chillers,lithium bromide absorption chillers,and heat pumps.For buildings with both heating and cooling demands,using a heat pump system for combined heating and cooling can achieve the highest efficiency when the ratio of heating demand to cooling demand is around 1.5.