应用固定投资费用松弛策略的换热网络优化

Fixed Investment Cost Relaxation Strategy for Heat Exchanger Network Synthesis

启发式算法优化有固定投资费用的换热网络时,由于存在整型变量而造成结构进化困难,提出固定投资费用松弛策略.对固定投资费用进行松弛处理实现对数学模型的简化,当换热器换热量很小时固定投资费用几乎为零,随着换热量的增大,固定投资费用以一定斜率逐步增大最终等于实际值.通过松弛强度系数控制变化斜率,在保证优化结果可靠性的基础上引导存在结构进化障碍的换热器生成或消去.对文献中两个算例的优化结果进行分析,考察不同松弛强度下对换热器生成、消去的作用.提出基于固定投资费用松弛策略的强制进化随机游走算法,并应用于换热网络实例.

In view of structural evolution difficulty caused by integer variables in heat exchanger network with fixed investment cost,a fixed investment cost relaxation strategy is proposed.It simplifies mathematical model of the problem by relaxing fixed investment cost.As heat exchanger is very small,fixed investment cost is almost zero.With increase of heat exchanger,fixed investment cost is gradually increased with a certain slope,and finally equals to the actual value.Controlling the change slope by the relaxation strength coefficient,on the basis of ensuring reliability of optimization results,heat exchangers with structural evolutionary obstacles are guided to generate or eliminate.The strategy is used to two cases in the literature,and effect of this strategy on generation or elimination of heat exchanger under different relaxation strength is investigated.Finally,a random walk algorithm with compulsive evolution based on fixed investment cost relaxation strategy is proposed.The algorithm is applied to a heat transfer network case.The result is superior to existing literature.