Dynamic characteristics of two shell-and-tube heat exchangers connected in parallel

This paper presents the results of the theoretical and experimental investigations on the dynamic characteristic of two shell-and-tube heat exchangers connected in parallel. One of the theoretical model on the dynamic characteristic of two heat exchangers connected in parallel is derived on the basis of the network theoretical viewpoint. The network theoretic model of the dynamic characteristics of a heat exchanger is represented as the interconnection of inner admittances, sources and sinks in parallel. Therefore the network connection of the inner admittances in two heat exchangers suggests the dynamics of the system. However, the model of the system that consists of two heat exchangers connected in parallel shows a series connection of the inner admittances. This implies the complexity of the dynamic characteristic of the parallel system. Some experimental investigations were carried out with two steam condensers cooled by water connected in parallel. In the investigations, three parameters are considered: (1) the size ratio of two heat exchangers, (2) the water flow rate ratio in two heat exchangers and (3) the ratio of transportation time difference in the water delivery pipings to water transportation time in the heat exchanger A. These investigations show that a relationship between the size andmore » flow rate ratio of the heat exchanger and the difference between transportation times from the heat exchanger outlet to the confluence extremely influence the dynamics of the system under the specified parameters. The conclusion suggests the importance of the matching the size and operating condition of each heat exchanger and the piping arrangement to the confluent junction.« less