Based on the combination of the second law of thermodynamics and thermo-economic principle with the asymptotic fouling model

the costobjective function and the optimal cleaning cycle of heat exchanger were formulated by introducing exergy transfer and heat transfer effectiveness for a heat exchanger subject to foulingThe results showed that the optimal cleaning cycle and the corresponding total cleaning cost determined by the second law of thermodynamics might be greater or smaller than those by the first law of thermodynamics

because exergy price was different from heat price more or lessIn the meantime

the optimal cleaning cycle

representing minimum cost of operation and maintenance of heat exchangers varied with flow patterns of heat exchanger

number of heat transfer units without fouling

the ratio of cold to hot fluids heat capacity

the cleaning time and the other cost parametersIn addition

the effect of the ratio of cold to hot fluids heat capacity and a smaller number of heat transfer units without fouling on the optimal cleaning cycle was not obvious as compared with other parameters.