preliminary assessment of waste heat recovery solution orc to enhance the performance of liquid air energy storage system

Abstract Liquid Air Energy Storage (LAES) is a novel energy storage system that stocks up energy by means of air liquefaction and recovers the cryogenic energy when required. The performance of LAES is actually limited both by the inefficiencies of liquefaction and discharge section leading to lower value of round trip efficiency compared to other energy storage solutions. This work investigates the thermodynamic feasibility of an integrated energy system consisting of a LAES system and Organic Rankine Cycle (ORC) in order to recover the waste heat released by the compression phase. To further improve the round trip efficiency of LAES, different integrated LAES-ORC system configurations have been modelled by means of the numerical software EES-Engineering Equation Solver v.10, which allows to compute the thermo-physical properties of the working fluids throughout the whole cycles. The LAES-ORC integrated systems are compared in terms of different performance indices such electric power output, round trip efficiency of stand-alone and integrated systems and recover efficiency of ORC. Moreover, since the potential benefits of waste heat recovery by means of ORC introduces a new capital and operative cost, an economic analysis has been carried out in order to determine the impact of ORC introduction in LAES economy. The results show that a tight integration between LAES and ORC allows to significantly improve the round efficiency (up to 20%) and reduce the pay-back period of stand-alone LAES as high as 6 %

Design of Z-Pinch and Dense Plasma Focus Powered Vehicles

Z-pinch and Dense Plasma Focus (DPF) are two promising techniques for bringing fusion power to the field of in-space propulsion. A design team comprising of engineers and scientists from UAHuntsville, NASA's George C. Marshall Space Flight Center and the University of Wisconsin developed concept vehicles for a crewed round trip mission to Mars and an interstellar precursor mission. Outlined in this paper are vehicle concepts, complete with conceptual analysis of the mission profile, operations, structural and thermal analysis and power/avionics design. Additionally engineering design of the thruster itself is included. The design efforts adds greatly to the fidelity of estimates for power density (alpha) and overall performance for these thruster concept

Part-load energy performance assessment of a pumped thermal energy storage system for an energy community

Research on pumped thermal energy storage (PTES) has gained considerable attention from the scientific community. Its better suitability for specific applications and the increasing need for the development of innovative energy storage technologies are among the main reasons for that interest. The name Carnot Battery (CB) has been used in the literature to refer to PTES systems. The present paper aims to develop an energy analysis of a CB comprising a high-temperature two-stage heat pump (2sHP), an intermediate thermal storage (latent heat), and an organic Rankine cycle (ORC). From a broad perspective, the CB is modeled considering two types of heat inputs for the HP: a cold reservoir in the ground (at a constant temperature of 12 °C throughout the entire year) and a heat storage at 80 °C (thermally-integrated PTES—TI-PTES). The first part defines simple models for the HP and ORC, where only the cycles’ efficiencies are considered. On this basis, the storage temperature and the kind of fluids are identified. Then, the expected power-to-power (round-trip) efficiency is calculated, considering a more realistic model, the constant size of the heat exchangers, and the off-design operation of expanders and compressors. The model is simulated using Engineering Equation Solver (EES) software (Academic Professional V10.998-3D) for several working fluids and different temperature levels for the intermediate CB heat storage. The results demonstrate that the scenario based on TI-PTES operation mode (toluene as the HP working fluid) achieved the highest round-trip efficiency of 80.2% at full load and 50.6% round-trip efficiency with the CB operating at part-load (25% of its full load). Furthermore, when the HP working fluid was changed (under the same scenario) to R1336mzz(Z), the round-trip full-load and part-load efficiencies dropped to 72.4% and 46.2%, respectively. The findings of this study provide the HP and ORC characteristic curves that could be linearized and used in a thermo-economic optimization model based on a Mixed-Integer Linear Programming (MILP) algorithm

Membrane-less hydrogen bromine flow battery

In order for the widely discussed benefits of flow batteries for electrochemical energy storage to be applied at large scale, the cost of the electrochemical stack must come down substantially. One promising avenue for reducing stack cost is to increase the system power density while maintaining efficiency, enabling smaller stacks. Here we report on a membrane-less hydrogen bromine laminar flow battery as a potential high-power density solution. The membrane-less design enables power densities of 0.795 W cm[superscript −2] at room temperature and atmospheric pressure, with a round-trip voltage efficiency of 92% at 25% of peak power. Theoretical solutions are also presented to guide the design of future laminar flow batteries. The high-power density achieved by the hydrogen bromine laminar flow battery, along with the potential for rechargeable operation, will translate into smaller, inexpensive systems that could revolutionize the fields of large-scale energy storage and portable power systems.American Society for Engineering Education. National Defense Science and Engineering Graduate FellowshipMIT Energy Initiative (Seed Fund

InP integrated optical frequency comb generator using an amplified recirculating loop

A novel realisation of photonically integrated optical frequency comb generation is demonstrated on indium phosphide (InP) using a generic foundry platform. The architecture, based on the amplified recirculating loop technique, consists of cascaded electro-optic phase modulators embedded within a short waveguide loop. While an injected continuous wave laser signal is recirculated by the loop, the modulators are driven with a modulation frequency corresponding to the round-trip loop length frequency. This results in many phase coherent, evenly spaced optical comb lines being generated. The choice of InP as an integration platform allows immediate optical amplification of the modulated signal by embedded semiconductor optical amplifiers, enabling loop losses to be compensated and expanding the comb across broad optical bandwidths. This approach reduces the requirement for external, high-power optical amplifiers, improving the compactness and power efficiency of the full system. The system was modelled to identify off-resonance behaviour, outlining limits in matching both the modulation frequency and seed laser frequency to the round-trip loop frequency for optimal comb line generation to be achieved. The experimental device occupied a fraction of the 6 x 2 mm2 InP chip and operated at round-trip loop frequencies of 6.71 GHz to produce 59 comb lines within a 20 dB power envelope. All comb lines exhibited strong phase coherence as characterised by low composite phase noise measurements of -105 dBc/Hz at 100 kHz. A second device is also presented with a shorter loop length operating at ~10 GHz which generated 57 comb lines. Both loop configurations included short waveguide phase shifters providing a degree of tunability of the free spectral range with a tuning range of 150 MHz for small injection currents of less than 2.5 mA.This research work has been supported by the UK Engineering and Physical Sciences Research Council (EPSRC) through the Integrated Photonics and Electronic Systems (IPES) Centre of Doctoral Training and PICSat project (EPSRC Reference: EP/S000976/1)

Lunar Prospecting: Searching for Volatiles at the South Pole

The Resource Prospector is an in-situ resource utilization (ISRU) technology demonstration mission, planned for a 2021 launch to search for and analyze volatiles at the Lunar South Pole. The mission poses unique operational challenges. Operating at the Lunar South Pole requires navigating a surface with lighting, shadow and regolith characteristics unlike those of previous missions. The short round trip communications time enables reactive surface operations for science and engineering. Navigation of permanently shadowed regions with a solar powered rover creates risks, including power and thermal management, and requires constant real time decision making for safe entry, path selection and egress. The mission plan requires a faster rover egress from the lander than any previous NASA rover mission

Transcritical Carbon Dioxide Charge-Discharge Energy Storage with Integration of Solar Energy

New and improved energy storage technologies are required to overcome non-dispatchability, which is the main challenge for the successful integration of large shares of renewable energy within energy supply systems. Energy storage is proposed to tackle daily variations on the demand side, i.e., storing low-price energy during off-peak or valley periods for utilization during peak periods. Regarding electrical energy storage, several technologies are available with different potentials for scalability, density, and cost. A recent approach for grid-scale applications is based on transcritical carbon dioxide charge and discharge cycles in combination with thermal energy storage systems. This alternative to pumped-hydro and compressed air energy storage has been discussed in scientific literature, where different configurations have been proposed and their efficiency and costs calculated. The potential of the concept has been demonstrated to be an economical alternative, including hybrid concepts with solar thermal storage. Even at low temperatures, the addition of solar energy has proved to be cost effective. This paper explores the effect of introducing solar-based high temperature heat on the performance of different configurations of “Transcritical carbon dioxide ‒ thermal energy storage system” cycles. A base-cycle with 8-hour discharge time is compared with different layouts. Discussions include details on the models, parametric analyses -including solar technology alternatives-, and simulation results. Round trip efficiency of the base case, without solar support and at pressure ratio of 9.4, is 52%. When solar input is considered, the efficiency is above 60%, increasing the turbine inlet temperature to 950 K. Estimated levelized cost of electricity values are in the range of pumped hydro and compressed air energy storage, 90-140 USD/MWh in agreement with other works on this thermal storage technology. The global analysis shows clear advantages for advancing in the study and definition of this technology for exploitation of synergies at different power ranges, integrated with mid/high temperature solar power plants and with smaller-scale renewable installations.Unión Europea. Fondo Europeo de Desarrollo Regional SOE1 / P3 / P0429E

Latency based device fingerprinting in a low-power industrial wireless sensor network

Security is a key challenge for any IIoT network and more so for constrained IWSN deployments. Novel methods are thus required to enhance security, taking into consideration the lossy and low power nature of the IWSN. The use of ICMP packets is proposed as a method to generate fingerprinting information for IWSN devices. The ICMP based method uses the round-trip time information in the ICMP header as a fingerprinting metric. The results showed that the effect of the physical layer can be averaged out of the measurement if enough samples are available. A linear relationship was found between hop count and round-trip time for a static network which can be used in the design phase of the IWSN network or alternatively as a method to fingerprint routing anomalies in real-time. The ICMP method was able to differentiate between devices from different vendors, but unable to fingerprint devices from the same vendor due to physical layer interference. The work shows that fingerprinting in an IWSN using the ICMP method is possible if the timing delta under investigation is an order of magnitude larger than the timing variation introduced by the physical layer while maintaining a reasonable signal-to-noise ratio.Dissertation (MEng (Computer Engineering))--University of Pretoria, 2021.Electrical, Electronic and Computer EngineeringMEng (Computer Engineering)Unrestricte