Heat Transfer Measurements with Surface Mounted Foil-Sensors in an Active Mode: A Comprehensive Review and a New Design

Abstract

A comprehensive review of film-sensors shows that they are primarily operated in a passive mode, i.e. without being actively heated to an extent, whereby they create a heat transfer situation on their own. Only when these sensors are used for wall shear stress measurements, the detection of laminar/turbulent transition, or the measurement of certain flow velocities, they are operated in an active mode, i.e. heated by an electrical current (after an appropriate calibration). In our study we demonstrate how these R(T)-based sensors (temperature dependence of the electrical resistance R) can also be applied in an active mode for heat transfer measurements. These measurements can be made on cold, unheated bodies, provided certain requirements with respect to the flow field are fulfilled. Our new sensors are laminated nickel- and polyimide-foils manufactured with a special technology, which is also described in detail.

A sensor for direct measurement of small convective heat fluxes: Validation and application to micro-structured surfaces

“…As mentioned in Ref. [11], such a feature is highly desirable and still represents a challenge for state-of-the-art flush mounted foil sensors.…”

“…artificial roughness) are planned in top of a macroscopic fin [18]. As mentioned above, a reliable measure of the convective heat transfer coefficient of these kind of surfaces is difficult to obtain with flush mounted sensor [10] [11]:…”

“…Another type of sensor that has recently gained great popularity are flush mounted sensors [10] [11], which are commonly used in heat transfer charac- gaining and increasing popularity (see e.g. [11,12]).…”

Influence of low temperature annealing on Nickel RTDs designed for heat flux sensing

“…Nickel has the advantage of being more cost-effective than platinum, therefore it is suitable for wide diffusion sensors or disposable applications as in biomedical sensing [1] [2]. Some authors worked on heat flux sensors using thin film nickel RTDs [3][4] [5]. In heat flux sensing, the heat flux can be derived from the difference of two temperature measurements.…”

Design and testing of a heat transfer sensor for well exploration tools

“…Sensors can measure heat transfer by measuring a temperature gradient in space, such as for planar [23] and thin foil sensors [24]; by measuring a temperature gradient in time and evaluating a time constant [25]; or by actively dissipating a controlled amount of heat. An extensive review of heat transfer sensors based on the thin foil technology is also reported in [26], with an overview on thinfilm heat flux sensors, which given the reduced thickness have a lower thermal disruption effect. Thermal studies in high-temperature [27] and high-pressure environments, such as die casting molds [28] or gas turbines [29,30], show how heat transfer measurements require the development of new materials, additional shielding of sensors, and even the integration of active cooling systems, which increase the complexity and the cost of the sensor.…”