Software Development And Research On Calculation Method Of The Helical Wound Heat Exchanger

As heat exchangers use widely in different industries, efficient heat exchangers is of great significance for saving energy. The helical wound heat exchanger is widely applied in rectisol process, chemical equipment, liquefied natural gas progress, air separation plant and so on, it has a broad application prospect. The paper is based on improvement project of aromatics isomerization feed heat exchanger of Luoyang ×× Co.Ltd, the heat transfer and pressure drop performance of the single-phase and two-phase flow on helical wound heat exchangers were intensively researched, and the design and calculation software was carried out. The main work and results are as follows:According to critical Reynolds number in Schmidt.E.F calculation formula, the winding diameter D_s is needed to repeatedly calculate, the average winding diameter (?) was proposed to instead of D_s for calculating the heat transfer coefficient of shell side; the equivalent diameter De and effective mass flow velocity of shell side Geff were modified and the heat transfer and pressure drop calculations of the single-phase flow heat exchanger were improved by the author. In addition, the fitting formula method of physical parameters and the structural design method of the helical wound heat exchanger were proposed, which was to be easy for programming calculation. Taking into account the special structural characteristic of helical wound heat exchanger, the physical parameter fitting formula was proposed,the unique structural design method of helical wound heat exchanger was set up, it was convenient for programming.Due to the complexity of two-phase flow heat transfer and technical confidentiality, on the basis of the boiling heat transfer of straight tube, the Dean number that is represent the structure characteristics of helical wound heat exchanger was used to modified the formula, the calculation method for the two-phase mono-steam helical wound heat exchanger was got when boiling heat transfer occured on shell side; the calculation method of Bays and McAdams and calculation method of R.W.Lockhart are corrected, and the applicable conditions were given; atthe same time, in order to improve the accuracy of calculation, the subsection calculation method applied on all types of heat exchangers was proposed, and the calculation method of the temperature of each segment point was given.On the basis of these fully-prepared work, the design and calculation software of the two-phase flow on the helical wound heat exchanger is designed using the VB programming language. The loop structure of the VB programming were used repeatedly in the progress to reduce the number of the code, friendly visual windows for every step calculation were created, besides, the link between VB and Word was established, in order that the design calculation results were saved in the word document for later verification and construction operation. Later, the software was validated and applied in the engineering by Luoyang ×× Co. Ltd, the results of the application in the engineering of the software show that the design and calculation method has certain reliability.