CFD Simulation of Effect of Geometric Parameters on the Gas Flow Distribution between the Main Route and the Bypass in the Microthermal Flow Meters for Domestic Use

Accurate measurement of gas flow is a basic need in domestic use. Diaphragm gas meters are currently used to measure domestic gas consumption, which is a very old and inaccurate technology. In recent years, the use of thermal MEMS flowmeters has been growing due to their small size, low power consumption, and good accuracy, but their limited measurement range has prevented them from being used to measure domestic gas consumption. In order to eliminate this limitation, in the present study, a bypass system similar to capillary tube flowmeters was introduced, which it has also been used in several commercial microthermal flowmeters. This system must be designed in such a way that an acceptable flow enters the bypass (microchannel). Therefore, in this study, for the first time, the effect of different geometrical parameters on the flow rate to the bypass in the flow range of domestic consumption was studied by simultaneously solving turbulent and laminar flow equations through fluid dynamics simulation. According to the results, with the higher the height of the bypass channel is, the smaller the diameter of the laminar flow element is and the less bypass-laminar flow element distance is, more gas enters the bypass. Finally, the channel height of 160 micrometers, the distance of 2 mm between bypass entrance and laminar flow element, and the square arrangement of the laminar flow element with a diameter of 1.8 mm can be appropriate. In these specifications, 100 to 220 percent more flow enters the bypass than most other configurations of the work.