Estimating the Flexibility Index of the Heat Exchanger Network by using the Confidence Level

Abstract

This paper presents a new technique to estimate the heat exchanger network flexibility index by using a statistical method. This method identifies the true value under uncertainty. The flexibility of the heat exchanger network (HEN) is one of factors which affect the operability of the system. This method was applied by the following a sequential procedure. First, the disturbance propagation of HEN was studied by generating the linear model which presents the relationship between the output disturbance of the target temperature and the disturbance in the operation condition in input such as the supply temperature and the flow rate of the heat capacity. The matlab application was used to generate this equation. Second, the stream with low sensitivity to this disturbance was selected. Third, the confidence level for the lower disturbance this stream was calculated. This method was applied on three published cases and their results were compared with the results of the new method. The new method provides a simple way to calculate the flexibility index for large heat exchanger networks..