State-space model for transient behavior of water-to-air surface heat exchanger
State-space model for transient behavior of water-to-air surface heat exchanger
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DOI：
10.1016/j.ijheatmasstransfer.2013.04.037
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发表时间：
2013-09
影响因子：
5.2
通讯作者：
Ye Yao;Mengwei Huang;J. Mo;Shanqi Dai
中科院分区：
文献类型：
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作者：
Ye Yao;Mengwei Huang;J. Mo;Shanqi Dai
准确地描述水-空气换热器在瞬态条件下的动态性能将有助于设计高能效HVAC系统的优化控制策略。本文将水-空气换热器视为多输入多输出系统，建立了相应的动力学模型，并在此基础上建立了状态方程和能量方程。建立了换热器瞬态特性的空间模型，并通过一系列动态响应实验进行了验证，包括出口空气温度和湿度的瞬态响应，以及出口水温受到入口水温的扰动（情况I：启动冷却器;和情况III：停止冷却器）和水流量的突然变化（情况II：水流量增加0.058 kg/s）。在所有情况下，瞬态响应模拟的实验验证时间均设置为1200 s。将状态空间模型的仿真结果与实验数据进行了比较，结果表明，本文建立的状态空间模型能够较好地预测水-空气换热器的瞬态性能（平均误差小于15.0%）。同时，通过模型仿真，讨论了输入扰动和初始条件对换热器瞬态行为的影响。结果表明，输入扰动和初始条件对响应变量的比例系数有显著影响，而对响应变量的时间常数影响不大。
Adequately representing the dynamic performance of a water-to-air heat exchanger under transient conditions would help design optimized control strategies for a high-energy-efficiency HVAC system. In this paper, the water-to-air heat exchanger is considered as a multi-input-and-multi-output system (MIMO), and the corresponding dynamic model is developed with the mass and energy balance equations based on which the state-space model for transient behavior of the heat exchanger is derived.The model has been validated by a series of dynamic response experiments including the transient responses of exit air temperature and humidity as well as exit water temperature subjected to the disturbances of inlet water temperatures (Case I: Start up the chiller; and Case III: Stop the chiller) and a sudden change in the water flow rate (Case II: The water flow rate increases by 0.058 kg/s). The time of experimental validation on the transient response simulation is set as 1200 s in all the cases. The simulated results obtained by the state-space model have been compared with the experimental data, which shows that the state-space model developed in this study is capable of predicting the transient performance of the water-to-air heat exchangers satisfactorily (the average error is less than 15.0%). Meanwhile, the influence of input disturbances and initial conditions on the transient behaviors of the heat exchanger is discussed through the model simulation. The results show that the input disturbances and the initial conditions will produce significant influence on the proportionality coefficient of the response variables, but little influence on the time constant of the response ones.