Performance Analysis And Optimization Study On Heat, Water And Power Cogeneration System

Exploiting seawater desalination technology is a hopeful approach to solve the problem for people to overcome the fresh water crisis in the world.At present,large dual-purpose power plants with the low temperature multi-effect distillation process has been used to reduce the fresh water cost.But how to further reduce the cost of fresh water is still the current research problem in the word.This paper presents and studies the heat,water and power cogeneration system.This paper develops mathematical model for this new system which includes low temperature multiple-effect seawater desalination system,lithium bromide absorption heat pump system and thermal vapor compression.In this foundation,this paper has also established the optimum mathematical model of the heat,water and power cogeneration system,which aims at minimum unit cost of fresh water,and the optimum mathematical model is solved by use of the Matlab Optimization Toolbox.Base on the results solved by the mathematical model,it has made a comparison for 5 different kinds of 6 effects MED-TVC serial systems.Compared with other 4 flows,the results show that the thermal performance and cost of fresh water of the 2+4 form is the best of all.Base on the results solved by the optimum mathematical model,it has made an optimal and non-optimal comparative study separately for the serial preheating flow system and the parallel preheating flow system,and it has made an optimal comparison for different flows system.Under the given condition,the results show that the optimum effect is distinct until the number of effects reaches 6.For the serial preheating flow system,when the number of effects reaches 6,the optimal fresh water cost is the lowest of all,which is 5.418ï¿¥/t,For the parallel preheating flow system,when the number of effects reaches 7,the optimal fresh water cost is the lowest of all,which is 4.884ï¿¥/t.When the number of effects is 6,compared with the serial preheating flow system,the savings rate of the parallel preheating flow system is 9.08%.The thermal performance and cost of fresh water of the parallel preheating flow system is the best of all.At last,it make a comparison for different cogeneration system with parallel preheating flow,which includes the non-cogeneration system,the water and power cogeneration optimal system and the heat,water and power cogeneration optimal system.The results show that the cost of fresh water of the non-cogeneration system is the highest,and the cost of fresh water of the heat,water and power cogeneration system is the lowest of all.When the total number of effects is 7,under the same condition,compared with the water and power cogeneration system,the savings rate of fresh water cost of the heat,water and power cogeneration system is 11.47%.Compared with the non-cogeneration system,the savings rate of fresh water cost of the heat,water and power cogeneration system reaches 77.36%.