چكيده به لاتين
Considering the value of gas and abundant resources in Iran, the accuracy of meters in measuring for export is of great importance. Measuring the accuracy of meters is done with flowloop during the calibration process. There is no laboratory in the country for calibrating high pressure gas meters, and the accuracy of the calibration process depends on the performance of the flow loop. For this reason, it is necessary to obtain optimal conditions for flowloop performance. The accuracy of the meter depends on the velosity profile and turbulence quantities, and it is necessary that velocity profile and turbulence quantities be developed before entering the meters. To simulate the gas flow in the pipe, it is necessary to solve the equations of continuity, motion and energy. In order to obtain the blower power and heat load of the exchanger, pressure drop and temperature changes must be obtained. For this purpose, the closed flow loop was simulated in a one-dimensional way with the help of comsol multiphysics 5.4 software at an initial temperature of 25 ℃, an ambient temperature of 25 ℃, a pressure of 25 to 50 bar, and a flow rate of 10 to 3600 m3/hr. In order to obtain the best header arrangement for the developed speed profile and to optimize the turbulence quantities, the equations have to be solved in three dimensions. In the three-dimensional simulation, five different types of headers that are used in famous laboratories in the world were simulated at a pressure of 50 bar, a constant temperature and a flow rate of 400 to 3600 m3/hr. In the one-dimensional simulation, in the second state, the pressure drop decreased by 15% compared to the first state, which is due to the decrease in the length of the pipe. In the third state, the pressure drop increased due to the increase in the pipe length. In the fourth case, the pressure drop was reduced due to the reduction of the pipe length and the reduction of the operating pressure. In the three-dimensional simulation of the third and fifth headers, the turbulence intensity is between 20 and 42% lower than the rest of the headers, the turbulence kinetic energy is between 43 and 48% lower, the turbulence loss is between 44 and 47% lower, and the rotation number for these headers is between 9 It decreased by 13%. In the examination and comparison of the speed profile and contour of the headers, the third and fifth headers were identified as the best headers. In order to make a more accurate comparison between the third and fifth headers, the quantity of the speed ratio was defined, and this quantity for the fifth header was equal to the third header for the diameter of 8in and for other diameters it was smaller than the third header.
