In this paper, the design and validation of a heat storage device based on phase change materials... more In this paper, the design and validation of a heat storage device based on phase change materials are presented, with the focus on improving the thermal control of micro-satellites. The main objective of the development is to provide a system that is able to keep electronics within safe temperature ranges during the operation of manoeuvres, while reducing mass and volume in comparison to other thermal control techniques. Due to the low thermal conductivity of phase change materials, the conductivity of the device as a whole is one of the major challenges of the development. This issue has been solved by means of the use of a lattice of aluminium fins. The thermal behaviour of the proposed solution is assessed with numerical simulation tools, and the results prove that the developed phase change material-based thermal control technique is able to provide the suitable integrated thermal management of micro-satellites. Fabrication challenges found in the project are also explained. Num...
Bonded composite patches are very appropriate for aircraft structural repair, showing very good p... more Bonded composite patches are very appropriate for aircraft structural repair, showing very good properties when compared with traditional mechanical fastening of metal sheets. The curing process of the composite patch must be done “onsite” and a direct resistive heating method has been proposed. The heat produced by the electric current through the Joule effect when crossing the patch carbon fibre bundles has been modelled with a Finite Element Program code, developed for the electric current equation. The heat conduction equation has also been modelled in the program, as well as the kinetics of the curing reaction of the composite resin. The electric resistivity of the materials is function of the temperature, so a nonlinear coupled system has been developed. Therefore, a complete simulation tool able to study different configurations, current intensities, materials, etc. for the composite patches is presented. A study case has been run with the developed code and results have been...
Abstract The thermal subsystem of spacecrafts and payloads is always designed with the help of Th... more Abstract The thermal subsystem of spacecrafts and payloads is always designed with the help of Thermal Mathematical Models. In the case of the Thermal Lumped Parameter (TLP) method, the non-linear system of equations that is created is solved to calculate the temperature distribution and the heat power that goes between nodes. The accuracy of the results depends largely on the appropriate calculation of the conductive and radiative conductances. Several established methods for the determination of conductive conductances exist but they present some limitations for complex geometries. Two new methods are proposed in this paper to calculate accurately these conductive conductances: The Extended Far Field method and the Mid-Section method. Both are based on a finite element calculation but while the Extended Far Field method uses the calculation of node mean temperatures, the Mid-Section method is based on assuming specific temperature values. They are compared with traditionally used methods showing the advantages of these two new methods.
Tribolab is a materials tribology experiment that was flown on the International Space Station (I... more Tribolab is a materials tribology experiment that was flown on the International Space Station (ISS) from February 2008 to September 2009. The main objective of the experiment was the study of the behaviour of new solid lubricants (alloyed MoS2 with WC) under real space conditions. The thermal control of the instrument (techniques needed to ensure that the temperature range of the experiment components are adequate in all the mission possible scenarios) was designed, assembled, integrated and tested by a team of engineers of Inasmet-Tecnalia and INTA. The design concept employed, mainly passive thermal control with some active components, is explained in detail. The computational models devised for the design, as well as the different mission scenarios are also explained. The verification and on earth qualification tests are described and the difficulties encountered during the project for the thermal subsystem are also explained. Finally, the real thermal behaviour of the experimen...
In this paper, the design and validation of a heat storage device based on phase change materials... more In this paper, the design and validation of a heat storage device based on phase change materials are presented, with the focus on improving the thermal control of micro-satellites. The main objective of the development is to provide a system that is able to keep electronics within safe temperature ranges during the operation of manoeuvres, while reducing mass and volume in comparison to other thermal control techniques. Due to the low thermal conductivity of phase change materials, the conductivity of the device as a whole is one of the major challenges of the development. This issue has been solved by means of the use of a lattice of aluminium fins. The thermal behaviour of the proposed solution is assessed with numerical simulation tools, and the results prove that the developed phase change material-based thermal control technique is able to provide the suitable integrated thermal management of micro-satellites. Fabrication challenges found in the project are also explained. Num...
Bonded composite patches are very appropriate for aircraft structural repair, showing very good p... more Bonded composite patches are very appropriate for aircraft structural repair, showing very good properties when compared with traditional mechanical fastening of metal sheets. The curing process of the composite patch must be done “onsite” and a direct resistive heating method has been proposed. The heat produced by the electric current through the Joule effect when crossing the patch carbon fibre bundles has been modelled with a Finite Element Program code, developed for the electric current equation. The heat conduction equation has also been modelled in the program, as well as the kinetics of the curing reaction of the composite resin. The electric resistivity of the materials is function of the temperature, so a nonlinear coupled system has been developed. Therefore, a complete simulation tool able to study different configurations, current intensities, materials, etc. for the composite patches is presented. A study case has been run with the developed code and results have been...
Abstract The thermal subsystem of spacecrafts and payloads is always designed with the help of Th... more Abstract The thermal subsystem of spacecrafts and payloads is always designed with the help of Thermal Mathematical Models. In the case of the Thermal Lumped Parameter (TLP) method, the non-linear system of equations that is created is solved to calculate the temperature distribution and the heat power that goes between nodes. The accuracy of the results depends largely on the appropriate calculation of the conductive and radiative conductances. Several established methods for the determination of conductive conductances exist but they present some limitations for complex geometries. Two new methods are proposed in this paper to calculate accurately these conductive conductances: The Extended Far Field method and the Mid-Section method. Both are based on a finite element calculation but while the Extended Far Field method uses the calculation of node mean temperatures, the Mid-Section method is based on assuming specific temperature values. They are compared with traditionally used methods showing the advantages of these two new methods.
Tribolab is a materials tribology experiment that was flown on the International Space Station (I... more Tribolab is a materials tribology experiment that was flown on the International Space Station (ISS) from February 2008 to September 2009. The main objective of the experiment was the study of the behaviour of new solid lubricants (alloyed MoS2 with WC) under real space conditions. The thermal control of the instrument (techniques needed to ensure that the temperature range of the experiment components are adequate in all the mission possible scenarios) was designed, assembled, integrated and tested by a team of engineers of Inasmet-Tecnalia and INTA. The design concept employed, mainly passive thermal control with some active components, is explained in detail. The computational models devised for the design, as well as the different mission scenarios are also explained. The verification and on earth qualification tests are described and the difficulties encountered during the project for the thermal subsystem are also explained. Finally, the real thermal behaviour of the experimen...
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Papers by Haritz Vallejo