Operation of heat exchanger networks under uncertainty

All heat exchanger networks (HEN's) are designed at given operating conditions, however, they usually do not operate at their design points, i.e., there exist deviations of some inlet parameters of process streams, thus the other inlet parameters need to be adjusted to maintain the target output temperatures of process streams. The operation problems of HEN under uncertainty can be divided into three cases: the number of adjustable parameters is greater than, or equal to, or less than the number of target output temperatures. If these deviations are within the feasible region of HEN, there may exist only one set, or more than one sets of adjustment solutions, to maintain its former target output temperatures, for the latter the optimal set need to be determined by using optimisation method. The results of examples show the approach is feasible.