Loop heat pipes (LHP) and other two-phase passive thermal devices, such as heat pipe loops (HPL), represent a very attractive solution for the energy management of systems characterized by a distributed presence of heating and cooling zones and by the needs of fast start-up, reliability, low cost and lightness. Even if the usual application for these devices is in the space sector, there could be a potential significant application for the automotive industry, for the development of embedded thermal networks for full electric vehicles (FEV), in order for example to recover the waste heat for cabin heating and cooling or to improve the aerodynamic efficiency. In the present investigation, the possibility to implement a new thermal control for an electric vehicle comprising from heat pumps (HP) and LHP, is here evaluated. In more detail, a 1-D lumped parameter model (LPM) that is able to predict the transient behaviour of a LHP in response of varying boundary and initial conditions, is developed and validated against literature experimental data. A novel methodology for treating numerically the condenser is proposed and validated for three different working fluids. An extensive parametric analysis is also conducted, showing the robustness of the thermal solution for different conditions and proving the possibility of using the proposed numerical code both for feasibility studies and for optimization purposes. A feasibility study utilizing the proposed model is also conducted and the results indicate that an array of LHPs can effectively transport heat from the motor section of the vehicle to the underbody, reducing significantly the aerodynamic losses.

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Power production research in the recent years is moving towards renewable energy sources with the aim to reduce CO 2 emissions. A potential means to overcome the obstacles placed by the intermittent nature of the most common sustainable energy sources is represented by the Liquid Air Energy Storage (LAES) systems. In order to improve its round trip efficiency, which is currently at 50%, the use of a common thermal medium for thermal storage and heat transfer fluid is considered as an effective solution. Molten salts were selected as the common thermal medium in this work, where a novel methodology for identifying and evaluating alternative mixtures is introduced. Firstly, various literature correlations were collected to form a thermo-physical property database of low melting temperature molten salts. These correlations were integrated in Aspen + by implementing a hybrid simulation technique for property estimation. These simulations were followed by a parametric analysis where 70 molten salt mixtures were evaluated in terms of thermo-physical properties by means of a performance and system index parameter. Following this process, 16 new molten salt mixtures were selected for the experimental campaign to measure their melting point temperature. As a result, two new alternative molten salt mixtures were found to have a low melting point of 95°C and 105°C, whilst providing a 37% and 34% increase in the performance indicator value. Hence, the presented methodology was proven to be an effective and versatile tool in identifying alternative salt mixtures, and can be adapted for comparable applications.

The power generation sector is moving towards more renewable energy sources to reduce CO 2 emissions by employing technologies such as the concentrated solar power plants and the liquid air energy storage systems. This work was focused on the identification of new molten salt mixtures to act as both, the thermal energy store and the heat transfer fluid in such applications. Firstly, a selection process utilizing literature data and Aspen + property package led to the identification of 5 nitrate-based mixtures offering suitable trade-off between melting point temperatures and volumetric heat capacities. Secondly, new salt compositions with improved volumetric heat capacities were created from the starting-point commercial molten salt mixtures, and then, experimentally tested for evaluating the melting point. Finally, volumetric heat capacity maps were created for the different temperature regimes, indicating 3 new temperature tailored molten salt mixtures, which use the same pure constituents as that of CaLiNaK and Quaternary.