Optimisation and thermal control of a multi-layered structure for
space electronic devices and thermal shielding of re-entry vehicles
$
Riccardo Monti
a,
n
, Renato Barboni
a
, Paolo Gasbarri
a
, Leonardo D. Chiwiacowsky
b
a
Dipartimento di Ingegneria Meccanica e Aerospaziale Universit
a degli Studi di Roma ‘‘La Sapienza’’, Rome, Italy
b
Programa de Po
´
s Graduac-
~
ao em Computac-
~
ao Aplicada, Universidade do Vale do Rio dos Sinos, S
~
ao Leopoldo/RS, Brazil
article info
Article history:
Received 27 June 2011
Received in revised form
4 November 2011
Accepted 15 January 2012
Available online 18 February 2012
Keywords:
Unsteady thermal problems
Pyroelectrics
Deterministic optimisation
Stochastic optimisation
abstract
All electronic devices, due to Joule effect, present heat dissipation, when they are electrically
fed. The heat overstocking produces efficiency and performances reduction. On account of
this the thermal control is mandatory. On small elect ronic equipments, the difficulty or
impossibility of using a cooling fluid for the free or forced convection heat dissipation
imposes the presence of cooling systems based on another kind of functioning principle such
as the conduction. In this paper the thermal control, via pyroelectric materials, is presented.
Furthermore, an optimisation of geometric, thermal and mechanical parameters, influencing
the thermal dissipation, is studied and presented. Pyroelectric materials are able to convert
heat into electrical charge spontaneously and, due to this capability, such materials could
represent a suitable choice to increase the heat dissipation. The obtained electric charge or
voltage could be used to charge a battery or to feed other equipments. In particular, a
sequence of different materials such as Kovar
s
, molybdenum or copper–tungsten, used in a
multi-layer pyroelectric wafer, together with their thicknesses, are design features to be
optimised in order to have the optimal thermal dissipation. The optimisation process is
performed by a hybrid approach where a genetic algorithm (GA) is used coupled with a local
search procedure, in order to provide an appropriate balance between exploration and
exploitation of the search space, which helps in the search for the optimal or quasi-optimal
solution. Since the design variables used in the optimisation procedure are defined in
different domains, discrete (e.g. t he number of layers in the pyroelectric wafer) and
continuous (e.g. the layers thickness) domains, the genetic representation for the solution
should take it into account. The chromosome used in the genetic algorithm will mix both
integer and real values, what will also be reflected in the genetic operators used in the
optimisation process. Finally, numerical analyses and results complete the work.
& 2012 Elsevier Ltd. All rights reserved.
1. Introduction
In the last decades the space design research has
been involved in the optimisation of missions, of costs,
of primary and secondary structures and of all other
equipments onboard the spacecraft. The thermal design
is one of the most important and expensive issues
of a spacecraft design. In fact the designer must pro-
vide a thermal protection system (TPS) in order to
control effects of external thermal sources (i.e. the
Sun heat flux) and efficient internal thermal devices to
drain the heat fluxes generated by the electronic
equipments.
Actually most of the internal thermal control is
provided by thermal pipes or by exploiting the thermal
characteristics of equipments constituting materials such
as the thermal conductivity in order to increase the heat
dissipation and to reduce the heat overstocking.
Contents lists available at SciVerse ScienceDirect
journal h omepage: www.elsevier.com/locate/actaastro
Acta Astronautica
0094-5765/$ - see front matter & 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.actaastro.2012.01.006
$
This paper was presented during the 61st IAC in Prague.
n
Corresponding author. Tel.: þ39 0644585301;
fax: þ 39 0644585670.
Acta Astronautica 75 (2012) 42–50
