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At least 379 records · Page 21

FPC conditioning cart at BNL

The 703 MHz superconducting gun for the BNL Energy Recovery Linac (ERL) prototype has two fundamental power couplers (FPCs), and each of them will deliver up to 500 kW of CW RF power. In order to prepare the couplers for high power RF service and process multipacting, the FPCs should be conditioned prior to installation into the gun cryomodule. A conditioning cart based test stand, which includes a vacuum pumping system, controllable bake-out system, diagnostics, interlocks and data log system has been designed, constructed and commissioned by collaboration of BNL and AES. This paper presents FPC conditioning cart systems and the conditioning process.

43 PARTICLE ACCELERATORS↗

Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes

Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 to test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Nanowire-integrated microporous silicon membrane for continuous fluid transport in micro cooling device

We report an efficient passive micro pump system combining the physical properties of nanowires and micropores. This nanowire-integrated microporous silicon membrane was created to feed coolant continuously onto the surface of the wick in a micro cooling device to ensure it remains hydrated and in case of dryout, allow for regeneration of the system. The membrane was fabricated by photoelectrochemical etching to form micropores followed by hydrothermal growth of nanowires. This study shows a promising approach to address thermal management challenges for next generation electronic devices with absence of external power.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

A Simulation Framework for Analyzing the Impact of Stochastic Occupant Behaviors on Demand Flexibility in Typical Commercial Buildings

As one of the primary users of the electric grid, buildings and building equipment, including heating, ventilation, and air conditioning (HVAC) systems, can be leveraged to provide the flexible demand needed to balance the grid. Typical strategies to achieve demand flexibility are to reduce electricity use during peak or critical periods by shutting down equipment or relaxing system setpoints, which will inevitably impact the occupants’ comfort. When occupants feel uncomfortable, they may take actions to regain their comfort, and some of those actions (such as turning on a personal fan) may have a negative impact on meeting the demand response goal. Therefore, it is important to incorporate occupant behaviors into the assessment ofthe building demand flexibility potential. In this study, a simulation framework that includes simulation of zone thermal loads, an HVAC system, and occupant behaviors, was developed to investigate the impact of occupant behaviors on demand flexibility. A case study was conducted using a small office model from the U.S. Department of Energy (DOE) Commercial Prototype Building Models to simulate the building envelope and zone loads. An agent-based occupant thermal behavior model was adapted to forecast occupants’ thermal comfort and their resulting thermal behaviors. An artificial neural network (ANN) based airflow model trained from a computational fluid dynamics (CFD) model of the zone was adopted to better predict the ambient environment of each occupant. An air-source heat pump simulation model that was calibrated from a real two-stage air-source heat pump system was used as the HVAC system. A typical load shedding event during peak hours was studied. Repeated simulations were conducted to capture the stochastic effects of occupant behaviors. The interplay between the demand flexibility, occupant comfort and behavior were analyzed by evaluating key performance indicators, including the energy use, occupant discomfort duration, and occupant behavior duration during the peak period. The results suggest that this framework can be used to analyze typical commercial buildings and their HVAC systems in terms ofdemand flexibility potential under the impact of occupant behaviors.

Chen, Zhelun↗

Low-z gas stripper as an alternative to carbon foils for the acceleration of high-power uranium beams

The RIKEN accelerator complex started feeding the next-generation exotic beam facility radioisotope beam factory (RIBF) with heavy-ion beams from 2007 after the successful commissioning of RIBF at the end of 2006. Many improvements made from 2007 to 2010 were instrumental in increasing the intensity of various heavy-ion beams. However, the available beam intensity of very heavy ion beams, especially uranium beams, is far below our goal of 1 p{mu}A (6 x 10{sup 12} particles/s). In order to achieve this goal, upgrade programs are already in progress; the programs include the construction of a new 28-GHz superconducting electron cyclotron resonance ion source and a new injector linac. However, the most serious problem, that of a charge stripper for high-power uranium beams, still remains unsolved, despite extensive research and development work using large foils mounted on a rotating cylinder and a N{sup 2} gas stripper. A gas stripper is free from problems related to lifetime, though the equilibrium charge state in this stripper is considerably lower than that in a carbon foil, owing to the absence of the density effect. Nevertheless, the merits of gas strippers motivated us to develop a low-Z gas stripper to achieve a higher equilibrium charge state even in gases. We measured the electron-loss and electron-capture cross sections of uranium ions in He gas as a function of their charge state at 11, 14, and 15 MeV/nucleon. The equilibrium charge states extracted from the intersection of the lines of the two cross sections were promisingly higher than those in N{sub 2} gas by more than 10. Simple simulations of charge development along the stripper thickness were performed by assuming the measured cross sections. The simulation results show that about 1 mg/cm{sup 2} of He gas should be accumulated to achieve a charge state higher than that of N{sub 2} gas, notwithstanding the difficulty in accumulation of this helium amount owing to its fast dispersion. However, we now believe that the following two solutions can overcome this difficulty: a gas cell with a very large differential pumping system and a gas cell with a plasma window. Their merits and demerits are discussed in the paper.

43 PARTICLE ACCELERATORS↗

Recovery Act - Geothermal Technologies Program: Ground Source Heat Pumps Final Scientific/Technical Report

A large centralized geothermal heat pump system was installed to provide ice making, space cooling, space heating, process water heating, and domestic hot water heating for an ice arena in Eagan Minnesota. This paper provides information related to the design and construction of the project. Additionally, operating conditions for 12 months after start-up are provided.

15 GEOTHERMAL ENERGY↗

High-order commutator-free exponential time-propagation of driven quantum systems

We discuss the numerical solution of the Schroedinger equation with a time-dependent Hamilton operator using commutator-free time-propagators. These propagators are constructed as products of exponentials of simple weighted sums of the Hamilton operator. Owing to their exponential form they strictly preserve the unitarity of time-propagation. The absence of commutators or other computationally involved operations allows for straightforward implementation and application also to large scale and sparse matrix problems. We explain the derivation of commutator-free exponential time-propagators in the context of the Magnus expansion, and provide optimized propagators up to order eight. An extensive theoretical error analysis is presented together with practical efficiency tests for different problems. Issues of practical implementation, in particular the use of the Krylov technique for the calculation of exponentials, are discussed. We demonstrate for two advanced examples, the hydrogen atom in an electric field and pumped systems of multiple interacting two-level systems or spins that this approach enables fast and accurate computations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

An analysis of the hybrid internal mass modeling approach in EnergyPlus

Accurate simulation of building system dynamics is particularly important for understanding building energy flexibility. Among all dynamics in a building, a zone temperature’s variation is especially important, as it significantly affects a building’s electricity load profile when its heating, ventilating, and air conditioning (HVAC) system is controlled with on/off cycles or setpoint reset strategies. To accurately simulate a zone temperature’s dynamics, internal mass needs to be modeled carefully. In this paper, we compare the two internal mass modeling approaches provided by EnergyPlus, i.e., internal mass object and zone air capacitance multiplier, to better understand their impacts on zone temperature simulation. Real building zone temperature dynamic data from small- and medium-sized office buildings are analyzed and compared with simulated data. In particular, we illustrate the effectiveness of a hybrid method of the two EnergyPlus modeling approaches, which yields more realistic zone temperature dynamics, especially when the zone is conditioned with heat pump systems with on/off cycling.

Chen, Zhelun↗

Status of not-in-kind refrigeration technologies for household space conditioning, water heating and food refrigeration

This paper presents a review of the next generation not-in-kind technologies to replace conventional vapor compression refrigeration technology for household applications. Such technologies are sought to provide energy savings or other environmental benefits for space conditioning, water heating and refrigeration for domestic use. These alternative technologies include: thermoacoustic refrigeration, thermoelectric refrigeration, thermotunneling, magnetic refrigeration, Stirling cycle refrigeration, pulse tube refrigeration, Malone cycle refrigeration, absorption refrigeration, adsorption refrigeration, and compressor driven metal hydride heat pumps. Furthermore, heat pump water heating and integrated heat pump systems are also discussed due to their significant energy saving potential for water heating and space conditioning in households. The paper provides a snapshot of the future R&D needs for each of the technologies along with the associated barriers. Both thermoelectric and magnetic technologies look relatively attractive due to recent developments in the materials and prototypes being manufactured.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Gain distribution in the volume of a solid-state active element of a diode-pumped high-power laser

We propose a technique for calculating the spatial gain profile in the volume of a solid active element of a high-energy laser pumped by laser diode arrays, which takes into account the properties of the radiation pattern of semiconductor lasers. This technique is employed to calculate the profile of the gain in a neodymium glass active element. By the example of a rod of rectangular section 4.5 by 4.5 by 25 cm we show that, by varying the pump system parameters, it is possible to define the profile of the gain: for instance, a profile uniform over the cross section (with its nonuniformity under 2.5%), with a peak at the centre or in peripheral regions, with a specific energy deposition of ∼1 J cm{sup −3}.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Numerical Modeling and Design of Gaseous Propellant Acquisition System for the Triton Hopper

Triton, the largest moon around Neptune, is a captured Kuiper Belt Object with a dynamic rarified atmosphere, active geysers, and unique “cantaloupe” like terrain. Little is known about Kuiper Belt Objects in the scientific community with most of the information coming from Pluto. Currently, NASA is designing an unmanned probe to explore the atmosphere and surface of Triton. This vehicle is unique in that it repeatedly takes off and lands (hops) using nitrogen propellant collected from its surroundings on Triton. This paper presents preliminary conceptual system design and numerical modeling of the atmospheric collection process. Four concepts are presented: a cryocooler-based system, a pump-based system, a sublimation and pump-based system, and a cryocooler and sublimation system. Numerical modeling takes into account the mass and energy transfer between all the relevant nodes in the system and is able to calculate the amount of nitrogen ice collected and ice accumulation rate as a function of time for each concept. The models are ultimately used to assess the feasibility of traversing from equator to pole in under two years using a gaseous propellant acquisition system for the Hopper.

Hopper↗

Development of an Air-Source Heat Pump Integrated with a Water Heating / Dehumidification Module

A residential-sized dual air-source integrated heat pump (AS-IHP) concept is under development in partnership between ORNL and a manufacturer. The concept design consists of a two-stage air-source heat pump (ASHP) coupled on the air distribution side with a separate novel water heating/dehumidification (WH/DH) module. The motivation for this unusual equipment combination is the forecast trend for home sensible loads to be reduced more than latent loads. Integration of water heating with a space dehumidification cycle addresses humidity control while performing double-duty. This approach can be applied to retrofit/upgrade applications as well as new construction. A WH/DH module capable of ~1.47 L/h water removal and ~2 kW water heating capacity was assembled by the manufacturer. A heat pump system model was used to guide the controls design; lab testing was conducted and used to calibrate the models. Performance maps were generated and used in a TRNSYS sub-hourly simulation to predict annual performance in a well-insulated house. Annual HVAC/WH energy savings of ~35% are predicted in cold and hot-humid U.S. climates compared to a minimum efficiency baseline.

dehumidification↗

ThermoLift – A Natural Gas Fired Air Conditioner and Heat Pump

ThermoLift is developing TC-Cycle™, a natural-gas driven air conditioner and cold-climate heat pump that can provide space heating, water heating, and air conditioning in a single device. Unlike traditional heat-pump system, the TC-Cycle system uses helium as working fluid in place of high global warming potential HFC refrigerant. The system has broad application as a combined HVAC solution and technology development throughout this program has advanced the Technology Readiness Level (TRL) from TRL-1 to TRL-5 achieved in the Gen 3.0 prototype. In August of 2013, the US Department of Energy (DOE) provided Research and Development funding through the Building Technologies Innovations Program Funding Opportunity Announcement DE-FOA-0000823. The statement of work (SOW) outlined a deliverable of testing at ORNL and a final test report prepared to include various heating cooling temperature ranges and performance analysis. Furthermore, a milestone of this effort was to analyze all test data to establish further efficiency improvements and consider optimum manufacturing methodologies to facilitate the next level improvements. ThermoLift’s Gen 3.0 gas-fired heat pump was shipped and installed into ORNL’s test facility with most of the data reported herein obtained on August 6, 2018. Uninterrupted operation demonstrated cycle Coefficient of Performance (COP) well exceeding DOE targets for cold-climate heat pumps. Furthermore, there was no degradation in capacity as inlet (ambient) temperature decreased.

03 NATURAL GAS↗

Short-Term Test Results: Multifamily Home Energy Efficiency Retrofit

Multifamily deep energy retrofits (DERs) represent great potential for energy savings, while also providing valuable insights on research-generated efficiency measures, cost-effectiveness metrics, and risk factor strategies for the multifamily housing industry. The Bay Ridge project is comprised of a base scope retrofit with a goal of achieving 30% savings (relative to pre-retrofit), and a DER scope with a goal of 50% savings (relative to pre-retrofit). The base scope has been applied to the entire complex, except for one 12-unit building which underwent the DER scope. Findings from the implementation, commissioning, and short-term testing at Bay Ridge include air infiltration reductions of greater than 60% in the DER building; a hybrid heat pump system with a Savings to Investment Ratio (SIR) > 1 (relative to a high efficiency furnace) which also provides the resident with added incentive for energy savings; and duct leakage reductions of > 60% using an aerosolized duct sealing approach. Despite being a moderate rehab instead of a gut rehab, the Bay Ridge DER is currently projected to achieve energy savings ≥ 50% compared to pre-retrofit, and the short-term testing supports this estimate.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Student Outreach With Renewable Energy Technology

The Student Outreach with Renewable Energy Technology (SORET) program is a joint grant that involves a collaboration between three HBCU's (Central State University, Savannah State University, and Wilberforce University) and NASA John H. Glenn Research Center at Lewis Field. The overall goal of the grant is to increase the interest of minority students in the technical disciplines, to encourage participating minority students to continue their undergraduate study in these disciplines, and to promote graduate school to these students. As a part of SORET, Central State University has developed an undergraduate research associates program over the past two years. As part of this program, students are required to take special laboratory courses offered at Wilberforce University that involve the application of renewable energy systems. The course requires the students to design, construct, and install a renewable energy project. In addition to the applied renewable energy course, Central State University provided four undergraduate research associates the opportunity to participate in summer internships at Texas Southern University (Renewable Energy Environmental Protection Program) and the Cleveland African-American Museum (Renewable Energy Summer Camp for High School Students) an activity co sponsored by NASA and the Cleveland African-American Museum. Savannah State University held a high school summer program with a theme of the Direct Impact of Science on Our Every Day Lives. The purpose of the institute was to whet the interest of students in science, mathematics, engineering, and technology (SMET) by demonstrating the effectiveness of science to address real world problems. The 2001 institute involved the design and installation of a PV water pumping system at the Center for Advanced Water Technology and Energy Systems at Savannah State. Both high school students and undergraduates contributed to this project. Wilberforce University has used NASA support to provide resources for an Applied Renewable Energy Laboratory offered to both Central State and Wilberforce students. In addition, research endeavors for high school and undergraduates were funded during the summer. The research involved attempts to layer photovoltaic materials on a conducting polymer (polypyrrole) substrate. Two undergraduate students who were interested in polymer research originated this concept. Finally, the university was able to purchase a meteorological station to assist in the analysis of the solar/wind hybrid power system operating at the university.

Clark, Eric B.↗

Impact of soil model complexity on the long-term thermal performance prediction of a new shallow bore ground heat exchanger

Shallow bore ground heat exchangers have been investigated in recent years because they have the potential to reduce the initial cost of the ground source heat pump system. Correctly modeling the transient heat transfer between the ground heat exchanger and the surrounding soil is essential for predicting a ground heat exchanger's performance. Simplification of the soil model could increase computation speed but sacrifice accuracy. This study investigates the impact of the soil model complexity on the annual performance prediction of a new shallow bore ground heat exchanger, the underground thermal battery (UTB). A simple 1D soil model and a more detailed 2D soil model were implemented, and they were validated against a 3D soil model. Overall, the resulting predictions of the UTB’s response from the 1D and 2D models to a given thermal load in different climates were compared. The results show that the root mean square differences between the hourly temperatures of the UTB during a year predicted using the two soil models range from 1.17°C to 3.39°C. As a result, the difference in the annual power consumption of the heat pump was between 0.7% and 3.4%. Furthermore, the dimensions of the UTB affected its performance, and a longer UTB was less sensitive to the soil models.

42 ENGINEERING↗

Ion Fluxes and Neutral Gas Ionization Efficiency of the 100-kW Light-Ion Helicon Plasma Source Concept for the Material Plasma Exposure eXperiment

Linear plasma devices are cost-effective alternatives for testing materials under reactor-relevant divertor plasma conditions. In this work, we describe how an intense radio-frequency (RF) plasma source concept for the Material Plasma Exposure eXperiment (MPEX) is under development at Oak Ridge National Laboratory. The source concept, Proto-MPEX, aims to produce high-density background deuterium helicon plasmas ( n e > 3 × 10 19 m - 3 ) that are subsequently heated with additional RF and microwave systems to deliver reactor-relevant conditions for studies on plasma-material interaction. In this work, we focus on the plasma-producing stage and its effectiveness in converting input neutral gas into plasma, namely, the neutral gas ionization efficiency. We provide a direct quantitative measurement of the ionization efficiency by measuring the total ion flux arriving at the target region relative to the neutral gas injected at the source. Using 80 kW at 13.56 MHz and a source magnetic field of 0.05 T, the helicon plasma source delivers ion fluxes up to 1 × 10 24 m - 2 s - 1 and heat fluxes greater than 1 M W m - 2 to a target plate located 2 m away from the source. Under these conditions, we observe that the plasma source converts ~89% of the input neutral gas into plasma that arrives at the target as ion flux at a rate of 5 × 10 20 s - 1 . We demonstrate that because of the large pumping capacity of the plasma, neutral gas pumping systems are required only in the target region to maintain optimal plasma operation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

High intensity high charge state ion beam production with an evaporative cooling magnet ECRIS

LECR4 (Lanzhou ECR ion source No. 4) is a room temperature electron cyclotron resonance ion source, designed to produce high current, high charge state ion beams for the SSC-LINAC injector (a new injector for sector separated cyclotron) at the Institute of Modern Physics. LECR4 also serves as a PoP machine for the application of evaporative cooling technology in accelerator field. To achieve those goals, LECR4 ECR ion source has been optimized for the operation at 18 GHz. During 2014, LECR4 ion source was commissioned at 18 GHz microwave of 1.6 kW. To further study the influence of injection stage to the production of medium and high charge state ion beams, in March 2015, the injection stage with pumping system was installed, and some optimum results were produced, such as 560 eμA of O{sup 7+}, 620 eμA of Ar{sup 11+}, 430 eμA of Ar{sup 12+}, 430 eμA of Xe{sup 20+}, and so on. The comparison will be discussed in the paper.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗