New method for automatic design of intensified shell and tube heat exchanger with twisted-tape insert
Shell and tube heat exchangers are the most widely used heat exchangers,and optimizing their design is a crucial research topic.Most existing design methods are based on heuristic methods or commercial solvers,which are slow in solving and can't guarantee the quality of design solutions.This paper applied set trimming to the automatic design of shell and tube heat exchangers.The outer diameter of tubes,the length of tubes,the diameter of the shell side,the number of tube sides,the pitch of twist-tapes,and the thickness of twist-tapes were defined as discrete variables and input into the program,which automatically output the design results and solutions.The automatic design optimization of shell and tube heat exchangers that intensified with twisted-tape insert was carried out by using single-objective optimization with the minimization heat exchange area,total annualized cost,and net present cost as optimization objectives.By comparison,we find that set trimming could ensure the global optimization of the design solution,and its solving time was very short.It could provide results within 0.5-2s.The results of minimizing the heat transfer area as the objective function showed that set trimming could obtain a smaller heat transfer area,which was reduced by 0.7%compared to the literature value.At the same time,the use of intensification techniques could reduce the heat transfer area.When the heat stream was distributed on the tube side,the technique reduced the heat transfer area by 7.7%,and the tube-side pressure drop increased by 16.9%.When the heat stream was distributed on the shell side,the heat transfer area was reduced by 14.6%,and the tube-side pressure drop increased by 98.7%.The optimization results with the objective of minimizing total annualized cost and net present cost showed that the cost of intensified conditions was lower than that of non-intensified states,and when the heat stream distribution was on the tube side,it was 13.1%lower.When distributed on the shell side,it was 0.57%lower.In addition,the cost of heat exchangers will also be affected by cost parameters.
heat exchangerheat transfer enhancementglobal optimizationset trimming
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