分布式冷热电联产系统的能量梯级利用率新准则

A New Evaluation Criterion of Distributed Energy Systems for CCHP——The Energy Cascade Utilization Efficiency

分布式冷热电联产系统评价准则对系统集成开拓与设计优化至关重要,传统的热效率、火用效率等难以全面科学地评估多供能系统性能特性,也不适于作为联产系统设计优化的目标函数。文章概述了目前常用的评价准则及其存在问题,基于热力学基本方程和联产系统的本质特征,提出了能量梯级利用率的评价准则。新准则从发电、制冷及供热等过程耗用能量的品位和生产产品的品质等来全面权衡不同能量转换利用过程的本质差异,并借助权重系数来综合量化描述。还结合实际的联产系统算例,对新准则和原有的评价准则进行比较分析。研究表明,该准则应用简便、合理、准确,为冷热电联产系统集成开拓与设计优化提供了一个更好的新准则。

The evaluation criterion is highly important for the distributed CCHP system （combined cooling, heating and power supply） to design and optimize. However, until now there is none of existing criterion yet, such as thermal and exergy efficiency and so on,that can provide satisfactory solutions. In this paper, some common criterion and its problems are summarized, and a new evaluation criteri- on of the distributed CCHP system, which is called energy cascade utilization efficiency, was proposed on the basis of energy cascade utilization principle and cogeneration feature. The new criterion evaluates the effectivity and energy consumed apportion of the CCHP system roundly from the quantity and quality of input and output energy in the cogeneration system and production processes of various levels energy. Meanwhile, the energy levels and weigh coefficient are employed to describe them numerically. Typical CCHP systems have been analyzed and compared by means of different common and new criterions. The result shows that the new evaluation criterion is more advantageous and reasonable and can be made as the practical evaluation criterion of CCHP system.