IR thermography measurement of convective coefficients in a pipe with periodic excitation

• A new method to measure heat transfer coefficients in tubes has been developed.
• This non-intrusive method requires a low heat flux.
• Fluid properties and flow rate knowledge are not required.
• A model has been developed to calculate heat transfer coefficient from wall temperature measurement.

A new methodology has been developed in order to measure heat transfer coefficients without requiring knowledge of fluid properties. This methodology is based on periodic excitation by Joule effect and infrared (IR) thermography measurement. It has been applied to measure heat transfer coefficients in the case of water flowing in a cylindrical copper tube. An analytical model has been developed to deduce heat transfer coefficients from the outside tube temperature amplitude and heat flux measurement. The Reynolds number ranges investigated are from 2000 to 14 000, with a heat flux varying from 1000 W m−2 to 5000 W m−2. The results obtained show good agreement with those obtained with a reference correlation in the literature, demonstrating the reliability of the methodology. This method can be applied to measure the heat transfer coefficients of complex shaped systems. The advantages of the method are the low heat flux required and its non-invasive nature.