Overall Design Project
Optimal Design and Operation Strategies of Hyperloop Transportation System
Duration
48 months
Start date
March 1, 2018
Financed by
Description
Historically, most transportation systems have been designed considering different boundary conditions and deployment scenarios. Particularly important is the definition of the characteristics of the energy reservoir that a given transportation system is using since this element determines whether the carrier of the system is energy-autonomous or not.
To fix ideas, electric trains (ETs) and electric vehicles (EVs), even if sharing similar propulsion technologies, leverage energy reservoirs of very different characteristics. ETs rely on a quasi-infinite energy reservoir represented by the power grid which, compared to the usual rated powers of trains’ propulsion systems, can be also considered as an infinite power source. Conversely, EVs rely on energy reservoirs (i.e., battery energy storage systems – BESS) characterised by limited gravimetric and volumetric energy and power densities.
Therefore, the design of these two transportation systems is radically different. Indeed, for ETs the energy reservoir does not translate into physical constraints that, on the contrary, need to be be well stated for the design of an EV in order to maximize their travel distance.The two above-mentioned transportation systems merge their characteristics when translated into the Hyperloop concept. Indeed, the Hyperloop presents the same advantages of ETs (high speed, low average energy consumption and CO2 emissions) being an energy-autonomous system.As known, Hyperloop capsules move between pre-determined and well-known trajectories in low-pressure tubes. The pressure in Hyperloop tubes is pumped down to values in the order of 1-10% of normal pressure or below, a condition that reduces drag forces and increases efficiency along with the maximum achievable speed.
This simple operational aspect dramatically reduces the energy needs of a Hyperloop capsule and, conversely, increases its maximum achievable speed. The actual vacuum proof materials enable a low leakage rate of the air. The consequence is that the propulsion system of a Hyperloop capsule may require a substantial amount of power (in the order of several MW per tens of tons of capsule mass) to be extracted from an energy reservoir containing a relatively low amount of energy. For this reason, the optimal sizing of a Hyperloop system is an interesting and non-trivial problem that represents one of the core elements of this research proposal along with the definition, and experimental validation, of optimal control strategies governing the capsule’s navigation system along a controlled environment.
Publications
2023
Authors: Denis Tudor
Abstract:
In the last decades, transportation demand growth has played a major role in the increase of global CO2 footprint. At the same time, a number of countries have scheduled measurable and substantial cutback of CO2 emissions by 2050. As the transportation sector has a significant carbon footprint, this process has triggered the need to develop new transportation alternatives. These can be split in two main categories: low-speed and high-speed transportation systems. While there are existing sustainable alternatives for low-speed (or medium-speed) transportation systems (i.e., electric vehicles, electric trains), the only high-speed transportation system that exists at this moment is the aviation. In terms of CO2, the emissions produced by the aviation sector are significant and, even though there are alternatives to aircrafts powered by fossil fuels (i.e., solar-based synthetic fuels or electric), they are technologically in their infancy.
Hyperloop could potentially represent a freight or passenger alternative to fossil-fuel powered aviation especially for intra-continental travels. The hyperloop comprises a network of capsules traveling at sub-sonic speed in a low-pressure constrained environment (i.e., a tube) embedding a set of rails for propulsion, levitation/suspension and guidance. The main advantages of a hyperloop system are associated to its energy efficiency and consequent sustainability gains produced by the large reduction of the drag aerodynamic losses and the adoption of a fully electric drivetrain.
One of the major challenges for the hyperloop is the construction of a radically new infrastructure involving extensive phases comprising feasibility studies, land expropriations, permits and civil constructions. Regarding the capsule design, the main challenge is conceiving and developing a solution that would eventually reduce the price of the infrastructure and leverage low-maintenance procedures. A major role here is played by the drivetrain system (i.e., propulsion, levitation and battery energy storage system).
Within this context, the thesis focuses on the development of various optimization frameworks to assess the optimal performance of the Hyperloop capsules propulsion with respect to their kinematic/propulsion models and the operation in the depressurized environment. Then, the thesis discusses how to optimally scale-down the hyperloop system in order to design reduced-scale mock-ups to be used in a fast-prototyping process of this new transportation system. The last part of the thesis illustrates an experimental testing facility under construction at the EPFL campus.
Published in: EPFL
Date of publication: January 18, 2023
2022
Authors: Denis Tudor; Tony Govoni; Malicia Leipold; Mario Paolone
Abstract:
The thorough development of the hyperloop system does require the availability of reduced-scale models. They can be used for the fast prototyping of various components, as well as for studying critical phenomena that takes place in this peculiar transportation system without the need to develop complex and expensive full-scale setups. In this respect, in this paper, we present a process for the optimal assessment of the scaling factor; it is to be used for the development of a reduced-scale hyperloop model, starting from the knowledge of the technical characteristics of its full-scale counterpart. The objective of the proposed process is the minimisation of the difference between the normalized power profiles associated with the reduced-scale and full-scale models of a hyperloop capsule traveling along a pre-defined trajectory with a pre-determined speed profile. By considering the hyperloop full-scale model as a reference, we propose a set of equations that link the above-mentioned metric with the constraints dictated by the kinematics of the hyperloop capsule, the capsule’s battery-energy storage and propulsion systems, the capsule’s aerodynamics, and the operating environmental conditions. We then derive a closed-form expression for the assessment of the optimal scaling factor and eventually use it to study the scaled-down version of an application example of a realistic hyperloop system.
Published in: 2022 IEEE 25th International Conference on Intelligent Transportation Systems (ITSC)
Date of publication: October 08-12, 2022
2021
Authors: Denis Tudor; Mario Paolone
Abstract:
We present an operational-driven optimal-design framework of a Hyperloop system. The novelty of the proposed framework is in the problem formulation that links the operation of a network of Hyperloop capsules, the model of the Hyperloop infrastructure, and the model of the capsule’s propulsion and kinematics. The objective of the optimisation is to minimize the energy consumption of the whole Hyperloop system for different operational strategies. By considering a network of energy-autonomous capsules and various depressurization control strategies of the Hyperloop infrastructure, the constraints of the optimisation problem represent the capsule’s battery energy storage system response, the capsule’s propulsion system and its kinematic model linked with the model of the depressurization system of the Hyperloop infrastructure. Depending on the operational scheme and lengths of the trajectories, the proposed framework determines optimal operating pressures of the Hyperloop infrastructure between 1.5-80 mbar along with the maximum capsules cruising speeds. Furthermore, the proposed framework determines maximum operational power of the capsule’s propulsion system in the range between 1.7-5 MW with a minimum energy need of 25 Wh/passenger/km.
Published in: Transportation Engineering
Date of publication: September, 2021
2019
Authors: Denis Tudor; Mario Paolone
Abstract:
In this article, we focus on the assessment of the optimal design of the propulsion system (PS) of an energy-autonomous Hyperloop capsule supplied by batteries. The novelty in this article is to propose a sizing method for this specific transportation system and answer the question whether the energy and power requirements of the Hyperloop propulsion are compatible with available power-electronics and battery technologies. By knowing the weight of a predetermined payload to be transported along predetermined trajectories, the proposed sizing method minimizes the total number of battery cells that supply the capsule’s propulsion and maximizes its performance. The constraints embed numerically tractable and discrete-time models of the main components of the electrical PS and the battery, along with a kinematic model of the capsule. Although the optimization problem is nonconvex due to the adopted discrete-time formulation, its constraints exhibit a good numerical tractability. After having determined multiple solutions, we identify the dominant ones by using specific metrics. These solutions identify PSs characterized by energy reservoirs with an energy capacity in the order of 0.5 MWh and a power rating below 6.25 MW and enable an energy consumption of 10-50 Wh/km/passenger depending on the length of the trajectory.
Published in: IEEE Transactions on Transportation Electrification
Date of publication: November 6, 2019
Authors: Denis Tudor; Mario Paolone
Abstract:
The paper assesses the influence of equivalent circuit battery models on the optimal design of the propulsion system of an energy-autonomous Hyperloop capsule. By knowing a pre-determined payload to be transported along pre-determined trajectories, the problem minimizes the total number of battery cells supplying the capsule propulsion along with the maximization of its performance. The constraints of the problem embed numerically- tractable models of the main components of the electrical propulsion systems and of the battery. Although the optimization problem is non-convex, its constraints are formulated to exhibit a good numerical tractability. After having determined the solutions influenced by a weighting factor with two different battery models, dominant solutions are identified using specific metrics with the purpose of assessing the impact of the battery model on the determined solutions.
Published in: 2019 IEEE Vehicle Power and Propulsion Conference
Date of publication: October 14-17, 2019