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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

A Comparison of the Environmental Effects of Open-Loop and Closed-Loop Pumped Storage Hydropower

Pumped storage hydropower (PSH) is a type of energy storage that uses the pumping and release of water between two reservoirs at different elevations to store water and generate electricity (Figure ES-1). When demand for electricity is low, a PSH project can use low cost energy to pump water from the lower reservoir to the upper reservoir for storage. When demand for electricity is high, a PSH project can release water from the upper reservoir through a powerhouse to generate electricity. Traditionally, this meant that PSH plants generated power during the day and pumped at night, with modest diurnal or seasonal variation.

13 HYDRO ENERGY↗
DOE OSTI2024

Field Validation of Electrochemical Water Filtration System on an Open Loop Cooling Tower at Nissan Manufacturing Plant in Canton, Mississippi

The U.S. Department of Energy Industrial Efficiency and Decarbonization Office’s Industrial Technology Validation (ITV) program aims to identify and demonstrate the performance of new, emerging, and underutilized technologies in the industrial sector to help inform decisions towards accelerating commercialization and deployment. This ITV demonstration investigated the performance of an early-commercial electrochemical water treatment technology on a cooling tower at an automotive plant. Cooling towers are vital equipment for dissipating heat from industrial processes, but they face challenges related to scaling, corrosion, and the growth of biological contaminants. Effective cooling tower water treatment is therefore essential in reducing these contaminants and other total suspended solids (TSS) and total dissolved solids (TDS). Various treatment systems, such as sand-based filters, centrifugal separators, and disc filters are available, each having its advantages and drawbacks. ElectroCell Systems, a filtration technology provider, offers an electrochemistry-based water treatment system that is skid-mounted and can be configured as a side-stream filtration system.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1973

Lp-stability (1 less than or equal to p less than or equal to infinity) of multivariable nonlinear time-varying feedback systems that are open-loop unstable

A class of multivariable, nonlinear time-varying feedback systems with an unstable convolution subsystem as feedforward and a time-varying nonlinear gain as feedback was considered. The impulse response of the convolution subsystem is the sum of a finite number of increasing exponentials multiplied by nonnegative powers of the time t, a term that is absolutely integrable and an infinite series of delayed impulses. The main result is a theorem. It essentially states that if the unstable convolution subsystem can be stabilized by a constant feedback gain F and if incremental gain of the difference between the nonlinear gain function and F is sufficiently small, then the nonlinear system is L(p)-stable for any p between one and infinity. Furthermore, the solutions of the nonlinear system depend continuously on the inputs in any L(p)-norm. The fixed point theorem is crucial in deriving the above theorem.

Callier, F. M.↗
NASA NTRS1977

Open-loop digital frequency multiplier

Monostable multivibrator is implemented by using digital integrated circuits where multiplier constant is too large for conventional phase-locked-loop integrated circuit. A 400 Hz clock is generated by divide-by-N counter from 1 Hz timing reference.

Moore, R. C.↗
NASA NTRS1975

Open-loop response of a burning liquid monopropellant

A direct comparison was obtained between the theoretical and experimental response of a burning liquid monopropellant surface to imposed pressure oscillations. The comparison extended beyond the quasi-steady frequency regime into the range where the combustion process interacts with the thermal wave in the liquid phase. The theory considered both gas and liquid-phase transient effects, involving a numerically integrated, first-order perturbation analysis. The experiment employed hydrazine as the test fuel, burning as a strand. With kinetic parameters fixed by steady burning rate measurements, the model gave good predictions of liquid-phase temperature distributions during steady combustion as well as the amplitude and phase of the oscillatory component of the burning rate in the presence of imposed pressure oscillations. The combustion response tends to peak in two frequency ranges; one corresponding to interaction with liquid-phase transient effects, which could be verified both theoretically and experimentally; the second corresponding to gas-phase transient effects, which could only be examined theoretically. Both ranges provide conditions where the amplifying power is sufficient to drive combustion instability.

Allison, C. B.↗
NASA NTRS1981

Considerations of open-loop, closed-loop, and adaptive multicyclic control systems

Four different types of self-tuning regulators were studied for multicyclic control of helicopter vibration. A numerical simulation of the helicopter is made, using a multivariable frequency-domain model, in terms of transfer function with six input control harmonics and six output harmonics. The model characteristics vary with flight speed. An off-line identification of model characteristics is made, using the least-squared-error method and using a succession of input and output measurements. The on-line identification of model characteristics is made using the Kalman filter solution. The optimal controls are calculated from the minimization of quadratic performance function based on response and multicyclic inputs. The performance of various regulators or controllers is judged from the stability, transient response, convergence time, and amplitude of the steady state.

Chopra, I.↗
NASA NTRS1989

Completing the forward kinematic calibration of open loop manipulators when single point position sensors are used

Single-point sensors can measure the position of one point fixed to a manipulator's end effector. When single-point sensors have been used for calibration, it has not been possible to calibrate the orientation of the tool. Furthermore, it can be difficult to calibrate the sensor system. Results in the literature seldom provide a complete kinematic calibration of the manipulator. Presented here is a technique that enables single-point sensors to gather sufficient information to complete kinematic calibration. In addition, the method can reduce the burden of calibrating the sensor system.

Everett, Louis J.↗
NASA NTRS1990

Results of aircraft open-loop tests of an experimental magnetic leader cable system for guidance during roll-out and turnoff

An experimental magnetic leader cable (MLC) system designed to measure aircraft lateral displacement from centerline and heading relative to centerline during rollout, turnoff, and taxi was tested at NASA's Wallops Flight Facility using NASA's Transport System Research Vehicle (TSRV), a modified B-737. The MLC system consisted of ground equipment that produced a magnetic field about a wire along runway centerline and airborne equipment that detected the strength and direction of this field and computed displacement and heading. Results of these tests indicate that estimates of aircraft displacement from centerline produced by the magnetic leader cable system using either of the two algorithms appear to be adequate for use by an automatic control system during rollout, turnoff, and taxi. Estimates of heading, however, are not sufficiently accurate for use, probably because of distortion of the magnetic field by the metal aircraft.

Bundick, W. Thomas↗
NASA NTRS1991

Coupled rotor-flexible fuselage vibration reduction using open loop higher harmonic control

A fundamental study of vibration prediction and vibration reduction in helicopters using active controls was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computer facility. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. It is shown that the conventional single frequency higher harmonic control is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. It is demonstrated that for simultaneous reduction of hub shears and fuselae vibrations a new scheme called multiple higher harmonic control is required.

Papavassiliou, I.↗
NASA NTRS1995

Open Loop Simulation

My project is designing a flight control program utilizing 'C' language. It consists of paths made up of fixed radius arcs and straight lines. Arcs will be defined by a center, a radius and turn angle. Straight lines will be defined by an end way point and an inbound course. Way points will be pre-defined such that the location of the end of each leg accurately matches the beginning of the next leg. The simulation paths will closely match paths normally flown by the Transport System Research Vehicle (TSRV), but will necessarily be defined identically in terms of type and number of way points.

Thomas, Tamera L.↗
NASA NTRS2013

Advanced Hybrid Spacesuit Concept Featuring Integrated Open Loop and Closed Loop Ventilation Systems

A document discusses the design and prototype of an advanced spacesuit concept that integrates the capability to function seamlessly with multiple ventilation system approaches. Traditionally, spacesuits are designed to operate both dependently and independently of a host vehicle environment control and life support system (ECLSS). Spacesuits that operate independent of vehicle-provided ECLSS services must do so with equipment selfcontained within or on the spacesuit. Suits that are dependent on vehicle-provided consumables must remain physically connected to and integrated with the vehicle to operate properly. This innovation is the design and prototype of a hybrid spacesuit approach that configures the spacesuit to seamlessly interface and integrate with either type of vehicular systems, while still maintaining the ability to function completely independent of the vehicle. An existing Advanced Crew Escape Suit (ACES) was utilized as the platform from which to develop the innovation. The ACES was retrofitted with selected components and one-off items to achieve the objective. The ventilation system concept was developed and prototyped/retrofitted to an existing ACES. Components were selected to provide suit connectors, hoses/umbilicals, internal breathing system ducting/ conduits, etc. The concept utilizes a lowpressure- drop, high-flow ventilation system that serves as a conduit from the vehicle supply into the suit, up through a neck seal, into the breathing helmet cavity, back down through the neck seal, out of the suit, and returned to the vehicle. The concept also utilizes a modified demand-based breathing system configured to function seamlessly with the low-pressure-drop closed-loop ventilation system.

Daniel, Brian A.↗
NASA NTRSDate not supplied

Design for an Integrated Open-Loop System for Carbon Dioxide Removal using Liquid Amine

Manned Space missions require maintaining a safe environment for the crew that can both sustain a breathable atmosphere and remove pollutants. Carbon dioxide, while not toxic in low concentrations, accumulates as crew members work and breath and can eventually affect the crew’s health. Therefore, a constant, passive system to remove the carbon dioxide build up is necessary for long-term missions. Currently, the prevailing liquid sorbent used in submarines and industrial flue gas utilizes the primary amine, monoethanolamine (MEA), to capture, transfer, and remove carbon dioxide from air. Diglycolamine (DGA) is an alternate primary amine that has similar performance and less volatility. It is currently being studied at Ames Research Center (ARC) and is the primary candidate for the operation of the sub-scale liquid amine test stand. The test stand is used to investigate liquid flow and liquid gas interfaces to assist in a system design for microgravity applications. The test stand includes a wedge design utilizes capillary action to hold the liquid while allowing gas-liquid interaction for carbon dioxide transfer. These wedge trays are placed in a contactor unit to remove carbon dioxide from the air stream, a degasser unit to replenish the liquid amine, and a capillary condensing heat exchanger (CCHX) to recapture water lost in the degasser unit. Nominal operating conditions for the contactor are a gas flow rate of 26scfm enriched with pure CO2 to 2600ppm and a liquid mixture of 65/35 vol% DGA/H2O at 0.65mL/min while the degasser was operated at 100°C and 1 atm. This paper discusses the challenges and limitations of a fully integrated system which will influence the design of a new subscale test stand.

Adrian Cortez↗
NASA NTRSDate not supplied

Comparison of Alternative Configurations of an Integrated Open-Loop Carbon Dioxide Removal System using Liquid Amine

Several carbon dioxide removal systems are being investigated for applications in microgravity. The liquid amine wedge system utilizes the capillary action of liquids to prevent the mixing of the air and liquid while still allowing for carbon dioxide capture at their interface. A one crew mission requires approximately 1 kg per day of carbon dioxide removal to prevent adverse health effects. A proposed design of a wedge tray system can be improved from the initial testing parameters to achieve the required carbon dioxide capture for one crew. The wedge trays in the contactor can be organized in either a parallel configuration to accumulate less CO2 in the liquid but at a higher flow rate or a series configuration to yield a higher weight percentage of CO2 in the liquid but at a lower flow rate. The gas flow rate and composition were held constant at 26scfm and 2600ppm, respectively, due to constraints of other proposed systems but the liquid flow rate was adjusted between 0.1mL/min and 10mL/min. The flow rate that yielded the best carbon dioxide capture was X mL/min and Y mL/min for the parallel and series configurations, respectively. The degasser temperature and pressure were varied from 80 to 100°C and 0 and -3 inHg. The largest carbon dioxide flux of Z kg/day/m2 was observed at a contactor liquid flow rate of X mL/min and a degasser temperature and pressure of T°C and P inHg.

Adrian Cortez↗