基于有限时间热力学的不可逆汽机热泵性能优化研究

Abstract

本文提出一种以供热抽汽驱动小汽轮机带动压缩式热泵工作的新型汽机热泵供热系统。新系统用小汽轮机代替凝气电厂的减温减压器，回收减温减压器浪费的能量，同时小汽轮机驱动热泵回收电厂循环冷却水的余热。引入汽机侧与热泵侧不可逆性能参数，对汽机侧和热泵侧进行了优化面积分配，得到了优化分配后的汽机效率和热泵性能系数关于设计参数的表达式，以供热率最大为优化目标，确定系统性能系数与制热率随设计参数与不可逆参数变化关系，并求出最大制热率下的性能系数表达式。通过某电厂改造参数对汽机热泵性能进行了数值分析，研究显示内不可逆参数对汽机热泵系统的性能比外部不可逆因素有更大的影响，研究还发现热泵侧不可逆因素对系统的影响大于汽机侧不可逆因素对系统的影响。 A new compression heat pump system driven by a small steam turbine which used the steam extraction as the power was developed to recycle the heat of cooling water in power plant. Temperature reducing was replaced by a small turbine and the energy lost in the temperature reducing was recycled. The System was considered as consist of an irreversible heat engine and an irreversible heat pump. Optimization was made on heat exchanger areas distribution. An optimal relation between performance coefficient of the system and heating load was obtained. The optimization model was tested and verified by a transformation of power plant in Dalian China. The results showed that internal irreversibility parameters have more drastic effect on performance reduction than any other external irreversibility parameters and the effects of the irreversible factors on the heat pump side was greater than the irreversible factors in the heat engine side on the system. Optimization results can provide guidance for the operation of the heat pump system driven by steam turbine.