Development of a portable thermogenerator for uncontrolled fire sources

JUANICÓ, L.E.; RINALDE G F; TAGLIALAVORE, E.

Aalborg

Congreso; 31th International & 10th European Conference; 2012

Aalborg Universitet

The full development of a portable thermogenerator based on a commercial (BiTe) thermoelectric module was performed. Its thermal modeling was fully developed, regarding the stationary states as well as thermal transients. This last issue causes major concerns, regarding the choice of uncontrolled fire source for the heat source and a self-powered fan for the heat sink. These choices imply that many potentially-dangerous behaviors could occur, as: 1) High temperature growing rates could cause fast overheating. So, the online reading of the temperature by user is not a suitable option for controlling the unit. 2) Low temperature growing rates could lead to temperature jumps of the thermopile lower that minimum necessary so that the self-powered fan can start running. This behavior in turns implies even lower temperature jumps, leading the generator into a "boiled-frog" negative-feedback process. So, the generator could be overheated without send any warning before to user. In this paper these both behaviors have been fully studied by numerical simulation. Different ranges of heat power and heat power rates are determined in order to assure the safety operation, and the generation of useful power. A prototype was completely built by using a standard G1-54-0557 Tellurex (maximum temperature of 175C) module. A microcontroller system was developed that supports a human machine interface (building by LED lights and piezoelectric buzzers) monitoring the temperature and calculating the temperature growing rate of the thermoelectric hot side in order to provide a warning in advance. Besides, the micro-controller can modify the self-consumed power of fan in order to optimize the net usable power. Experimental tests performed allow us to validate the physical modeling.