Experimental and numerical analysis of heat transfer phenomena in a sensor tube of a mass flow controller

Abstract

As a mass flow controller is widely used in many manufacturing processes for controlling a mass flow rate of gas with accuracy of 1%, several investigators have tried to describe the heat transfer phenomena in a sensor tube of an MFC. They suggested a few analytic solutions and numerical models based on simple assumptions, which are physically unrealistic. In the present work, the heat transfer phenomena in the sensor tube of the MFC are studied by using both experimental and numerical methods. The numerical model is introduced to estimate the temperature profile in the sensor tube as well as in the gas stream. In the numerical model, the conjugate heat transfer problem comprising the tube wall and the gas stream is analyzed to fully understand the heat transfer interaction between the sensor tube and the fluid stream using a single domain approach. This numerical model is further verified by experimental investigation. In order to describe the transport of heat energy in both the flow region and the sensor tube, the Nusselt number at the interface between the tube wall and the gas stream as well as heatlines is presented from the numerical solution. In Chapter 2, the numerical model is presented in the axisymmetric coordinate to simulate the heat transfer phenomena in the sensor tube of the MFC. The sensor tube considered in this model is the single heater type. It is assumed that the velocity profile is fully developed while the temperature profile is just being developed in the flow region. The governing equations and solution methods for the conjugate heat transfer problem are presented. In order to describe the transport of heat energy in the flow region as well as in the tube wall, the heatfunction is defined. Results for the temperature profiles and heatlines obtained numerically using the single domain approach are validated by benchmarking the program used in the present analysis. In Chapter 3, the surface temperatures at the tube wall measured by th...