Types of Thermal Mass Flowmeters

Two types of thermal mass flow meters

  1. Thermal Anemometer
  2. Temperature rise flow meter

Thermal mass flowmeters are devices used to measure the mass flow rate of a fluid by utilizing the principles of heat transfer. They operate based on the cooling effect of the fluid on a heated element or the heat transfer from a heated element to the fluid. There are several types of thermal mass flowmeters, each with its advantages and applications. Here are the main types:

Constant Temperature Anemometers (CTA): CTA flowmeters maintain a constant temperature difference between two temperature sensors—one heated and one unheated. The fluid’s flow rate is determined by the power required to maintain this temperature difference.

Constant Current Anemometers (CCA): CCA flowmeters maintain a constant current through the heated element. The cooling effect of the flowing fluid on the heated element changes the element’s temperature, and the current required to maintain the temperature is proportional to the flow rate.

Differential Temperature Anemometers (DTA): DTA flowmeters measure the temperature difference between a heated element and an unheated reference element. The temperature difference changes with flow, and the flow rate is determined based on this temperature difference.

Heat-Transfer Gas Mass Flowmeters: These flowmeters have a heated element that is exposed to the flowing gas. The amount of heat transferred from the heated element to the gas is used to determine the gas flow rate.

Heat-Transfer Liquid Mass Flowmeters: Similar to heat-transfer gas mass flowmeters, these flowmeters have a heated element in contact with the liquid, and the amount of heat transferred to the liquid is used to calculate the flow rate.

Capillary Thermal Mass Flowmeters: Capillary thermal mass flowmeters use a small capillary tube or channel with a heated element. The flow rate is determined based on the amount of heat carried away by the fluid flowing through the capillary.

MEMS (Micro-Electro-Mechanical Systems) Thermal Mass Flowmeters: MEMS-based thermal mass flowmeters use miniaturized sensors and electronics, offering compact size and low power consumption. They are commonly used in various applications, including microfluidics.

Each type of thermal mass flowmeter has its advantages in terms of accuracy, response time, and suitability for specific fluids and flow ranges. When choosing a thermal mass flowmeter, it is essential to consider the specific requirements of the application, such as the type of fluid, flow rate range, pressure, temperature, and environmental conditions.