ABSTRACT
The heated meter bar technique uses temperature sensors along the constant cross-section lengths of a material of known thermal conductivity to quantify the heat flux to an exposed face. Importantly, careful positioning of the temperature sensors allows for extrapolation of the temperature distribution to the exposed face, allowing a non-contact surface temperature measurement. The technique is elegant in its simplicity and, by offering simultaneous and non-contact measurement of surface heat flux and surface temperature, it has been used in a myriad of thermal fluid science studies over the past century, ranging from pool boiling to thermal interface materials. While the heated meter bar technique is simple in principle, some associated pitfalls must be avoided, especially considering the wide range of research areas where the technique can be applied. Particularly, since each application requires a bespoke design, there are countless combinations of design configurations, geometries, heat fluxes, operating temperatures, instrumentation options, accuracy requirements, and other aspects that must be addressed when designing a heated meter bar system. Of particular importance is the accurate quantification of the experimental uncertainty. This chapter addresses the approaches and techniques for the accurate quantification of heat flux and surface temperature using the heated meter bar technique. The foundation of the chapter is a new Monte Carlo technique for accurate and robust characterization of the experimental uncertainties related to the approach. A “design for uncertainty” approach is discussed whereby the uncertainty analysis is implemented at the early-stage design phase. In addition, the overall design process, design guidelines, material selection, fabrication techniques, sensors, and calibration options are discussed. This chapter concludes by discussing two case studies where the technique has been deployed. This chapter is intended to give practitioners the tools required to design, fabricate, calibrate, and use heated meter bars for their unique engineering or research applications.
