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At least 1,315 records · Page 73

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DOE OSTI2017

Building America Case Study: Heat Pump Water Heater Ducting Strategies with Encapsulated Attics in Climate Zones 2 and 4, LaFayette, Georgia (CZ4), and Savannah, Georgia (CZ2)

The focus of this study is on the performance of HPWHs with several different duct configurations and their effects on whole building heating, cooling, and moisture loads. A.O. Smith 60 gallon Voltex (PHPT-60) heat pump water heaters (HPWHs) were included at two project sites and ducted to or located within spray foamed encapsulated attics. The effect of ducting a HPWH's air stream does not diminish its efficiency if the ducting does not reduce intake air temperature, which expands HPWH application to confined areas. Exhaust ducts should be insulated to avoid condensation on the exterior, however this imposes a risk of condensation occurring in the duct's interior near the HPWH due to large variation of temperatures between the compressor and the duct and the presence of bulk moisture around the condenser. The HPWH's air conditioning impact on HVAC equipment loads is minimal when the intake and exhaust air streams are connected to a sealed attic and not the living space. A HPWH is not suitable as a replacement dehumidifier in sealed attics as peak moisture loads were observed to only be reduced if the heat pump operated during the morning. It appears that the intake air temperature and humidity was the most dominant variable affecting HPWH performance. Different ducting strategies such as exhaust duct only, intake duct only, and exhaust and intake ducting did not have any effect on HPWH performance.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2017

Building America Case Study: Heat Pump Water Heater Ducting Strategies with Encapsulated Attics in Climate Zones 2 and 4, LaFayette, Georgia (CZ4), and Savannah, Georgia (CZ2)

Building America↗

DOE OSTI2017

Design and Development of a Residential Gas-Fired Heat Pump

Heating, ventilating, and air-conditioning equipment consumes 43% of the total primary energy consumption in U.S. households. Presently, conventional gas furnaces have maximum heating efficiencies of 98%. Electric air conditioners used in association with the furnace for cooling have a minimum seasonal energy efficiency ratio (SEER) of 14.0. A residential gas-fired heat pump (RGHP) was developed and tested under standard rating conditions, resulting in a significant increase in heating efficiency of over 40% versus conventional natural gas furnaces. The associated efficiency of the RGHP in cooling mode is comparable in efficiency to an electric air conditioner (14.0 SEER) when compared on a primary energy basis. The RGHP is similar in nature to a conventional heat pump but with two main differences. First, the primary energy savings are higher, based on a site versus source comparison, as the result of using natural gas to supply shaft power to the compressor rather than an electric motor. Second, waste heat is recovered from the engine to supplement space heating and reduce the energy input. It can also be used to provide supplemental water heating. The system utilizes a programmable logic controller that allows variable-speed operation to achieve improved control to meet building loads. RGHPs significantly reduce peak electric use during periods of high demand, especially peak summer loads, as well as peak winter loads in regions with widespread use of electric heating. This contributes to leveling year-round gas loads, with the potential to increase annual gas demand in some regions. The widespread adoption of RGHPs will contribute to significant reductions in primary energy consumption and carbon emissions through improved efficiencies.

energy efficiency↗

DOE OSTI2018

Market Opportunities and Challenges for Pumped Hydro in an Evolving Power Grid: Preprint

The paper explores several market opportunities and challenges for pumped storage hydropower (PSH) related to ongoing changes in the electric power grid. Two PSH technologies are investigated - single-speed pump/turbine and variable-speed pump/turbine units - under three variable generation penetration scenarios. The results provide a way to do relative comparisons of the opportunities and challenges that pumped storage hydro faces as the variable generation in a system increases.

13 HYDRO ENERGY↗

DOE OSTI2019

Grid Integration and Market Analysis of Adjustable-Speed Pumped Storage Hydropower: Preprint

Many of the products and services on the electrical grid are currently provided by the conventional power plants, however the response time from conventional power plants is slow compared to hydropower. Similarly, some services such as spinning reserve can be provided by modern renewable generation (wind or PV), however the renewable generation must be curtailed down, thus there is loss of opportunity to harvest clean energy while operating in spinning reserve mode. On the other hand, Adjustable Speed - Pumped Storage Hydropower (AS-PSH) can readily perform these functions while pumping or generating, thus also taking benefit of energy arbitrage which can increase system efficiency. This paper will present results from production cost models showing the effect of adding AS-PSH 50 MW in size to three regional ISO areas which have different ancillary service markets available and different generation mixes. The benefits to these market areas from the ancillary services that can be provided by the AS-PSH and also the load shifting benefits will be measured with cost savings and additional system flexibility in the day-ahead and real-time markets. The main metrics to provide this insight will be savings in the total system production cost and in variable renewable energy curtailment respectively. The simulated operation of the additional hydropower will be analyzed to determine the breakdown of system cost reduction by ancillary services provided and load shifting.

13 HYDRO ENERGY↗

DOE OSTI2019

Pumped Thermal Electricity Storage with Supercritical CO2 Cycles and Solar Heat Input: Preprint

Pumped Thermal Electricity Storage (PTES) is an energy storage device that uses grid electricity to drive a heat pump to generate hot and cold storage reservoirs. This thermal potential is later used to power a heat engine and return electricity to the grid. In this article, a PTES variant that uses supercritical carbon dioxide (sCO2) as the working fluid is introduced. sCO2-PTES cycles have higher work ratios and power densities than the systems based on ideal gases that have been investigated to date. Furthermore, sCO2-PTES cycles may achieve higher round-trip efficiencies for a given hot storage temperature (up to 78% at 560 degrees C). The sensitivity of PTES cycles to loss factors such as isentropic efficiencies and temperature differences between the power cycle and storage fluid is investigated. A second concept whereby an sCO2-PTES cycle is integrated with concentrating solar power (CSP) is introduced. This concept 'time-shifts' the recompression of an sCO2 recompression cycle to a period of lower electricity prices and stores the heat. When solar heat is dispatched, the recompressor may be avoided as the required heat is obtained from storage, thereby leading to increased heat engine efficiencies. The net work output of this integrated system is 10-18% greater than the conventional recompression cycle. Combining PTES with a CSP power cycle is therefore shown to improve the dispatch of solar heat as well as providing electricity storage services.

14 SOLAR ENERGY↗

DOE OSTI2021

Detailed Evaluation of Electric Demand Load Shifting Potential of Heat Pump Water Heaters

Future utilities will emphasize home appliances to reduce greenhouse gas emissions while providing electric load shifting and demand profile management. Heat pump water heaters (HPWH) have demonstrated the ability to cut water heating energy by more than 65% compared with conventional electric resistance waters (ERWH). Laboratory research was conducted on the load shifting potential of grid-connected heat pump water heaters (HPWH), compared to ERWHs. Testing applied different CTA-2045 command designs. Highly-controlled laboratory experiments were conducted on one ERWH and four HPWHs, including a prototype incorporating the new CTA-2045-B protocol feature allowing ‘advanced’ load up above the tank setpoint. The prototype unit with the B-protocol increased tank temperature by 15oF (8.3C) under the advanced load up providing an increase of 1.8 kWh of storage for a 50-gallon (189 liter) tank. The prototype includes a built-in mixing valve to meet anti-scalding codes. With the load-shaping ability of CTA-2045-B, utilities might be able to store excess renewable energy in connected tanks when renewable wind and solar resource production is high. Tests were performed under baseline conditions (no load shift) and under several load-shifting schemes, including load up and advanced load up, ahead of shed commands. Grid-connected HPWHs reduced peak demand by as much as 0.5 kW, depending on tank volume, time of day, control scheme, and draw profile.

heat pump water heater, Demand flexibility, load s↗

DOE OSTI2023

Energy Model to Evaluate Thermal Energy Storage Integrated with Air Source Heat Pumps: Preprint

Full decarbonization in buildings requires the replacement of combustion appliances with electric ones, and air source heat pumps (ASHP) are a candidate alternative. However, technical limitations, such as the efficiency decrease when operating in cold weather, limit their adoption in the global heating market. Among several options to improve ASHP efficiency operating in colder climates, thermal energy storage (TES) has been considered, as it may provide heating when it is cold and shift ASHP operation to times when the weather is warmer. It may also take advantage of time of use electricity rates and support defrosting when necessary. The evaluation of ASHP-TES systems, however, is still limited because traditional metrics do not capture their full economic and environmental benefits. In this work, a python framework is presented to model the ASHP with and without the presence of TES. Metrics are proposed to analyze the system performance in terms of costs, equivalent CO2 emission, and efficiency metrics to evaluate and compare alternative systems. Model validation against experimental data obtained for a commercial heat pump is provided, as well as an application example using Denver, Colorado, to highlight the model capabilities.

cold climate↗

DOE OSTI2023

Coolant Pump Predictive Data Analytics from Signatures Generated by the Recursive Short Time Fast Fourier Transform

Although a nuclear reactor is a hostile environment for sensors and signal transmissions, the reactor core is amenable to acoustic communication. An acoustic measurement infrastructure installed at the Advanced Test Reactor (ATR) nozzle trench area records acoustic signals that can capture reactor operating states. The distinct states produce unique signatures that can be identified and tracked using data processing and data analytics. The infrastructure relies on acoustic transmission through ATR in-pile structural components, piping, and coolant that transmit acoustically modified signals generated by the coolant pumps. This paper will discuss results from using the Recursive Short Time Fast Fourier Transform (RSTFFT) technique used to process acoustic signals and provide signatures that are identified and monitored by analytics. The RSTFFT is applied to ATR data to understand the vibration levels and signatures for different operating regimes as displayed by the spectrogram. The combination of coolant pumps for normal and high-power operation generate unique signatures. These acoustic signatures are used to develop machine learning approaches to automatically classify operating regimes. Two machine-learning models, Support Vector Machines and Linear Discriminant Analysis, were developed to classify two event classes. Class 1 is a normal steady-state operation, and Class 2 is any event that is due to start up, shut down, or other actions. Both types of machine learning models had over a 96% prediction accuracy for the two classes. These results lay the foundation for predictive analytic frameworks that can be leveraged by ATR to optimize operations and maintenance.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2016

Assessing the Performance of Pump-and-Treat Systems - 16380

Pump-and-treat (P and T) is a common groundwater remedy. However, a challenge with P and T remedies has been in evaluating their performance. A structured approach can be applied to gathering the information needed to support assessment of P and T remedies and decisions to close the remedy, continue P and T, optimize the P and T system, or transition to other remedy approaches. Supportive decision elements include analysis of contaminant concentrations and trends, quantifying contaminant mass discharge of plume and source zone, quantifying the attenuation capacity of the aquifer, using tools to predict future plume behavior and time to reach remedial action objectives, and information about the current P and T system design and operations. Several sites have successfully conducted a P and T performance assessment and supported decisions to change their remedy approach. These case studies are discussed in relation to a recent document, Performance Assessment for Pump-and-Treat Closure or Transition, that provides guidance for the assessment process and associate remedy decisions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2022

Improving Reliability, Weight and Cost of Gas-Fired Absorption Heat Pumps

The objective of the project was to identify and verify a viable path for the use of aluminum tubes in evaporators for gas-fired ammonia-water absorption heat pumps (GAHP), via identification of a suitable alloy, coating, inhibitor, process, or combination, for the purpose of achieving weight and cost reduction.

03 NATURAL GAS↗

DOE OSTI2023

Strongly Correlated Exciton-Magnetization System for Optical Spin Pumping in CrBr 3 and CrI 3 .

Ferromagnetism in van der Waals systems, preserved down to a monolayer limit, attracted attention to a class of materials with general composition CrX 3 (X=I, Br, Cl), which are treated now as canonical two-dimensional ferromagnets. Their diverse magnetic properties, such as different easy axes or varying and controllable character of in-plane or interlayer ferromagnetic coupling, make them promising candidates for spintronic, photonic, optoelectronic, and other applications. Still, significantly different magneto-optical properties between the three materials, have been presenting a challenging puzzle for researchers over the last few years. Herewith, we demonstrate that despite similar structural and magnetic configurations, the coupling between excitons and magnetization is qualitatively different in CrBr 3 and CrI 3 films. Through a combination of the optical spin pumping experiments with the state-of-the-art theory describing bound excitonic states in the presence of magnetization, we concluded that the hole-magnetization coupling has the opposite sign in CrBr 3 and CrI 3 and also between the ground and excited exciton state. Consequently, we demonstrate efficient spin pumping capabilities in CrBr 3 driven by magnetization via spin-dependent absorption and unraveled the different origins of the magnetic hysteresis in CrBr 3 and CrI 3 are unraveled

36 MATERIALS SCIENCE↗

DOE OSTI2024

Quantization of the Higher Berry Curvature and the Higher Thouless Pump

Here, we show that for families of 1d lattice systems in an invertible phase, the cohomology class of the higher Berry curvature can be refined to an integral degree-3 class on the parameter space. Similarly, for families of U(1)-invariant 2d lattice systems in an invertible phase, the higher Thouless pump can be refined to an integral degree-2 class on the parameter space. We show that the 2d Thouless pump can be identified with an excess Berry curvature of a flux insertion.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2019

Simulation of Endovascular Aortic Repair Using 3D Printed Abdominal Aortic Aneurysm Model and Fluid Pump

Background: Abdominal aortic aneurysm (AAA) models can be manufactured with 3D printing technology. This study describes detailed methodology and validation of endovascular aortic repair (EVAR) simulation using 3D printed AAA model connected to hemodynamic pump. Method: The AAA model was printed with Objet500 Connex3 (Stratasys, Eden Prairie, MN) and connected to BDC PD-0500 fluid pump (BDC Laboratories, Wheat Ridge, CO). EVAR procedure metrics were benchmarked in two expert implanters and compared to 20 vascular surgical trainees with different levels of EVAR experience (< 20 or ≥ 20 cases). All simulations were performed using commercially available stent grafts, guidewires, catheters, fluoroscopic guidance and digital subtraction angiography. Studied outcomes included ability to complete the procedure independently, time to deploy aortic component, ability to cannulate contralateral gate and complete the repair, and total fluoroscopy and procedure times. Results: A total of 22 EVAR simulation procedures were performed with mean procedure time of 37 ± 12 min. Experienced trainees had significantly lower total procedural time (32 ± 9 vs. 44 ± 6 min, P = 0.003) and fluoroscopic time (13 ± 5 vs. 23 ± 8 min, P = 0.005). All experienced trainees completed the procedure independently in < 45 min, compared to six (46%) of those with less EVAR experience (P = 0.016). Among less experienced trainees, only two (15%) completed the entire procedure independently (P < 0.001). Benchmark implanters performed significantly better than both trainee groups in nearly all EVAR metrics. Conclusion: EVAR simulation was feasible and simulated all procedural steps with high fidelity. This model may be applicable for assessment of technical competencies and standard endovascular skill acquisition within vascular surgery training curricula.

3D PRINTING↗

DOE OSTI2018

Temperature Effects on the Optical Parameters of a Passively Q-Switched Diode-Side Pumped Yb,Er-Laser

Temperature effects on photoluminescence and absorption spectra of the active medium (LGS-DE erbium phosphate glass) and passive Q-switch (MgAl{sub 2}O{sub 4}:Co{sup 2+} crystal) of a diode-side pumped Yb,Er-laser are studied. The obtained data are applied to an analysis of the spectral and energetic characteristics of compact erbium emitters. It is established that the dominant generation channel in the temperature range 233–328 K is the optical transition between lower Stark sublevels of Er{sup 3+} states {sup 4}I{sub 13/2} and {sup 4}I{sub 15/2} (λ = 1532.0–1533.9 nm). A rate-equation system taking into account thermal population of Stark sublevels of states {sup 4}I{sub 13/2} and {sup 4}I{sub 15/2} is proposed to describe the experimental temperature dependence of the threshold absorbed power of the pumping radiation. This system and the lasing threshold enable modeling of Yb,Er-emitter output energetic and temporal characteristics.

36 MATERIALS SCIENCE↗

DOE OSTI2021

A physics-based parametric regression approach for feedwater pump system diagnosis

Here in this paper, we assessed the performance of a model-based approach for fault diagnosis of a nuclear power plant feedwater pump system. Physics-based models were constructed to monitor the performance of the system components. Plant data were used for the calibration of the models and subsequently in the diagnosis of abnormal events. We considered two real-time events representing scenarios of a pump fault and component performance degradation. The two events were correctly diagnosed, and the results demonstrated the high detection sensitivity of the physics-based models. Various sensor fault scenarios were simulated to show the capability of the approach to detect and uniquely identify sensor faults. Results for a scenario in which the plant operated in flexible power mode also showed that the diagnostic approach is insensitive to changes of operating conditions, which is one of the advantages of the model-based approach using physics-based models over purely data-driven approach.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2015

Exergy Analysis of a Two-Stage Ground Source Heat Pump with a Vertical Bore for Residential Space Conditioning under Simulated Occupancy

This twelve-month field study analyzes the performance of a 7.56W (2.16- ton) water-to-air-ground source heat pump (WA-GSHP) to satisfy domestic space conditioning loads in a 253 m 2 house in a mixed-humid climate in the United States. The practical feasibility of using the ground as a source of renewable energy is clearly demonstrated. Better than 75% of the energy needed for space heating was extracted from the ground. The average monthly electricity consumption for space conditioning was only 40 kWh at summer and winter thermostat set points of 24.4°C and 21.7°C, respectively. The WA-GSHP shared the same 94.5 m vertical bore ground loop with a separate water-to-water ground-source heat pump (WW-GSHP) for meeting domestic hot water needs in the same house. Sources of systemic irreversibility, the main cause of lost work are identified using Exergy and energy analysis. Quantifying the sources of Exergy and energy losses is essential for further systemic improvements. The research findings suggest that the WA-GSHPs are a practical and viable technology to reduce primary energy consumption and greenhouse gas emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources.

15 GEOTHERMAL ENERGY↗

DOE OSTI2020

Discovery of multidrug efflux pump inhibitors with a novel chemical scaffold

Multidrug efflux is a major contributor to antibiotic resistance in Gram-negative bacterial pathogens. Inhibition of multidrug efflux pumps is a promising approach for reviving the efficacy of existing antibiotics. Previously, inhibitors targeting both the efflux transporter AcrB and the membrane fusion protein AcrA in the Escherichia coli AcrAB-TolC efflux pump were identified. In this work we use existing physicochemical property guidelines to generate a filtered library of compounds for computational docking. We then experimentally test the top candidate coumpounds using in vitro binding assays and in vivo potentiation assays in bacterial strains with controllable permeability barriers. We thus identify a new class of inhibitors of E. coli AcrAB-TolC. Six molecules with a shared scaffold were found to potentiate the antimicrobial activity of erythromycin and novobiocin in hyperporinated E. coli cells. Importantly, these six molecules were also active in wild-type strains of both Acinetobacter baumannii and Klebsiella pneumoniae, potentiating the activity of erythromycin and novobiocin up to 8-fold.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗