The dynamics of heat exchangers networks, parallel and series connections of two heat exchangers are investigated. Experiments using two steam-condensers cooled by water in tubes are also performed and show the validity of our model on thedynamics. The characteristics of the parallel system is mainly influenced by a stream splitting, i.e., the flow rate distribution and the transportation lag-time in the pipe connecting each heat exchanger and a confluence point. The magnitude and phase of water (cold stream) outlet temperature change against a water flow rate change input show a fluctuation in a lower frequency range. In the same manner, the magnitude and phase of the series system also show a fluctuation in a lower frequency range. Thesebehaviors are caused by the effect of the size ratio of the first heat exchanger to the secondary one and the lag-time in the pipe connecting each heat exchanger. Consequently, it is clarified that both the parallel and series system are sensitive to thetransportation lag-time in pipe. This shows the importance of a fluid transportation model in the pipe on the dynamics of the system.
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