Development and Testing of a Multiplexed Temperature Sensor
Аннотации
Researchers studying phenomena associated with steep surface temperature
gradients, such as boiling, need to be able to obtain a detailed surface temperature
distribution. Such a distribution can be obtained by taking measurements at a number of
discrete locations on the surface using multiple individual temperature sensors. Because
each sensor requires at least two electrical connections, this approach has historically
been limited to relatively few temperature measurements; the most extensive
measurements made this way are still limited to a 10 × 10 array.
A new temperature sensor has been developed to address this measurement
problem. The new sensor consists of a 32 × 32 array of diode temperature sensors in a
10.24 mm2 area, with each component diode measuring 100 × 100 micron^2. Unlike previous
array-type sensors, the new sensor uses a multiplexing scheme to reduce the number of
external leads required; only 64 leads are required to obtain measurements from over
1000 individual temperature sensors. The new sensor also incorporates eight resistive
heater elements to provide the heat flux to initiate and sustain boiling. The heaters are
capable of delivering up to 100 W/cm^2.
This dissertation describes the design and testing of the new temperature sensor
and the supporting hardware and software. The system is demonstrated by determining
the local heat transfer coefficients for a jet of FC-72 from a 0.241 mm diameter nozzle.
The surface temperature distribution is measured for various combinations of applied heat
flux, jet velocity, and nozzle standoff distance; these measurements are then used to
determine the local heat transfer coefficient distribution. These measured values compare
favorably to those predicted using several correlations available in the literature.