the Heat Transfer Laboratory (HTL) is composed by five experiments, of which EXP1, EXP2, EXP3 and EXP4 are located inside the HTL, with an envelope of 300x300x200 mm divided into four equally spaced cavities by four aluminium sheets. The location of these experiments as well as their geometry can be seen in next figure.

CAD design of EXP1, EXP2, EXP3 and EXP4 of the HTL.

The main objective of the Heat Transfer Lab is to quantify the convective heat transfer in each of its four cavities, which contain a heated plate in different configurations. The selected heaters are shown in the following figure.

Heaters of the HTL experiments
(EXP4 heater at left and EXP1-3 at right).

Inside the gondola structure the Heat Transfer Lab will carry experiments 1 to 4 based on silicon heaters covered by aluminium plates and positioned in different configurations to quantify convective heat transfer. Heater power would be controlled by the electronics based on the configured powers modes during the flight. The ground station user will be also capable of controlling the dissipated power based on the evolution of the temperatures during the flight. For that reason, the plates and cavity temperatures would be monitored from the ground station. In addition, all wall temperatures will be measured. To do so, PT1000 thermo-resistances will be used on a 2-wire configuration. Experiment 4 will quantify the efficiency of an own manufactured thermal strap that will be connected to a radiator facing outside the gondola.

Experiment 5 will be also placed on a surface looking to outside the gondola to measure the relative wind speed using differential pressure sensors.

Knowing the temperatures of the walls, air and power dissipated at each instant in the flight of BEXUS, a transient analysis will be carried out in ESATAN with these data, so that the result obtained for the plate temperature in each experiment can be compared with the real temperatures measured by the thermistor.