Abstract:

In building applications,electrical load and thermal load vary significantly.And they are not synchronized.Therefore,the mismatch issue between energy supply and demand should be solved.The use of thermal storage systems could help improving energy demand coupling with energy generation profiles.The former researches pay attention on the influence of the size of the thermal storage.In this paper,the influences of three thermal storage strategies(TSS)on CCHP system are evaluated and analyzed.Firstly,the dynamic and control model is built by using TRNSYS and MATLAB software.Secondly,the principle and distinction of these three TSSs are analyzed.The traditional thermal strategy(TSS1)determines the operation of power generation Unit(PGU)only by the energy demand of the building.The active thermal storage strategy(TSS2)determines the on-off operation of PGU only by the state of the storage tank.The novel thermal storage strategy(TSS3)determines the operation of PGU by both energy demand and the state of the tank.Lastly,the impacts of TSSs on the performance of CCHP system are evaluated and analyzed through a case study of a hospital in Shanghai.The results show that TSS3 has the best performance.Compared with TSS1 and TSS2,operation time of PGU is longer,and more electric and thermal energy are produced by PGU to satisfy the demand of building with the same size of the storage tank.It is said that the storage capacity of the tank is effectively used to improve the performance of the system.When electricity produced by CCHP system cannot sell to the grid,the energy saving potential of CCHP system is significantly limited.

Key words: combined cooling, heating and power system, thermal storage, dynamic simulation, exergy, modeling, strategy

摘要：

冷热电联供是天然气高效利用的重要方面。以上海某医院为例,基于Trnsys与Matlab软件建立了天然气冷热电联产系统的动态仿真与控制模型。对传统蓄能策略、"主动蓄能"策略和新型蓄能策略进行了描述。利用该模型计算了系统在不同蓄能容量与控制策略下的效率、一次能源节约率和投资回收期,并进行了对比分析。结果表明,"主动蓄能"策略下联供系统对建筑供能的贡献率低,性能差于其他蓄能策略;新型蓄能策略下的系统运行时间能得到很大的延长。它能有效发挥蓄能设备的作用,使联供系统为建筑提供更多的高效能量。电力不能上网的条件下,联供系统的节能潜力受到很大的限制。

关键词: 冷热电联供, 蓄能, 动态仿真, (火用), 模型, 控制策略