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At least 163 records · Page 9

All sources NASA NTRS DOE OSTI

DOE OSTI2016

The New S-RAM Air Variable Compressor/Expander for Heat Pump and Waste Heat to Power Application

S-RAM Dynamics (S-RAM) has designed an innovative heat pump system targeted for commercial and industrial applications. This new heat pump system is more efficient than anything currently on the market and utilizes air as the refrigerant instead of hydrofluorocarbon (HFC) refrigerants, leading to lower operating costs, minimal environmental costs or concerns, and lower maintenance costs. The heat pumps will be manufactured in the United States. This project was aimed at determining the feasibility of utilizing additive manufacturing to make the heat exchanger device for the new heat pump system. ORNL and S-RAM Dynamics collaborated on determining the prototype performance and subsequently printing of the prototype using additive manufacturing. Complex heat exchanger designs were fabricated using the Arcam electron beam melting (EBM) powder bed technology using Ti-6Al-4V material. An ultrasonic welding system was utilized in order to remove the powder from the small openings of the heat exchanger. The majority of powder in the small chambers was removed, however, the amount of powder remaining in the heat exchanger was a function of geometry. Therefore, only certain geometries of heat exchangers could be fabricated. SRAM Dynamics evaluated a preliminary heat exchanger design. Although the results of the additive manufacturing of the heat exchanger were not optimum, a less complex geometry was demonstrated. A sleeve valve was used as a demonstration piece, as engine designs from S-RAM Dynamics require the engine to have a very high density. Preliminary designs of this geometry were successfully fabricated using the EBM technology.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2025

Virtual Refrigerant Charge Sensing Method for Next-Generation Refrigerant in Residential Heat Pumps

The charge level of refrigerant in heat pump systems significantly affects their operational performance. Virtual refrigerant charge (VRC) sensing technology has been well-established for traditional refrigerants (HFCs and HCFCs) for its low cost compared to physical sensors. However, other than traditional refrigerants, HFOs are increasingly used in next-generation heat pumps; whether these conventional VRC sensing methods remain applicable for heat pump systems utilizing next-generation refrigerants requires further investigation. To address these issues, this study develops a low-cost VRC sensing method for next-generation refrigerant heat pumps used in residential buildings. The developed algorithm is evaluated by using simulation models to evaluate the accuracy, considering an R454B heat pump with a nominal heating capacity of 51K Btu/hr (14.95 kW) as an example, and compared with those of the two reference VRC sensing algorithms. Though the developed VRC sensing algorithm and the two reference methods can accurately predict the charge level for the R454B heat pump system (with mean absolute percentage error for various cooling and heating conditions less than 7%), the developed VRC sensing algorithm uses fewer sensors and improves the overall accuracy for heating conditions by 7.1%, and the accuracy for undercharge cooling conditions 14.2%, compared with a mainstream algorithm. This technology will complement physical leakage detectors, and promote the adoption of next-generation heat pump systems, along with reducing wasted energy and maintenance costs.

Liang, Chenjiyu↗

NASA NTRS2012

Development of a Dual-Pump CARS System for Measurements in a Supersonic Combusting Free Jet

This work describes the development of a dual-pump CARS system for simultaneous measurements of temperature and absolute mole fraction of N2, O2 and H2 in a laboratory scale supersonic combusting free jet. Changes to the experimental set-up and the data analysis to improve the quality of the measurements in this turbulent, high-temperature reacting flow are described. The accuracy and precision of the instrument have been determined using data collected in a Hencken burner flame. For temperature above 800 K, errors in absolute mole fraction are within 1.5, 0.5, and 1% of the total composition for N2, O2 and H2, respectively. Estimated standard deviations based on 500 single shots are between 10 and 65 K for the temperature, between 0.5 and 1.7% of the total composition for O2, and between 1.5 and 3.4% for N2. The standard deviation of H2 is ~10% of the average measured mole fraction. Results obtained in the jet with and without combustion are illustrated, and the capabilities and limitations of the dual-pump CARS instrument discussed.

Magnotti, Gaetano↗

NASA NTRS1965

Residual-gas analysis of a DC-705 OIL diffusion-pumped uhv system.

Residual gases in oil-diffusion-pump ultrahigh vacuum determined as function of various trapping conditions

ULTRAHIGH VACUUM↗

DOE OSTI2015

Stand Alone Battery Thermal Management System

The objective of this project is research, development and demonstration of innovative thermal management concepts that reduce the cell or battery weight, complexity (component count) and/or cost by at least 20%. The project addresses two issues that are common problems with current state of the art lithium ion battery packs used in vehicles; low power at cold temperatures and reduced battery life when exposed to high temperatures. Typically, battery packs are “oversized” to satisfy the two issues mentioned above. The first phase of the project was spent making a battery pack simulation model using AMEsim software. The battery pack used as a benchmark was from the Fiat 500EV. FCA and NREL provided vehicle data and cell data that allowed an accurate model to be created that matched the electrical and thermal characteristics of the actual battery pack. The second phase involved using the battery model from the first phase and evaluate different thermal management concepts. In the end, a gas injection heat pump system was chosen as the dedicated thermal system to both heat and cool the battery pack. Based on the simulation model. The heat pump system could use 50% less energy to heat the battery pack in -20°C ambient conditions, and by keeping the battery cooler at hot climates, the battery pack size could be reduced by 5% and still meet the warranty requirements. During the final phase, the actual battery pack and heat pump system were installed in a test bench at DENSO to validate the simulation results. Also during this phase, the system was moved to NREL where testing was also done to validate the results. In conclusion, the heat pump system can improve “fuel economy” (for electric vehicle) by 12% average in cold climates. Also, the battery pack size, or capacity, could be reduced 5%, or if pack size is kept constant, the pack life could be increased by two years. Finally, the total battery pack and thermal system cost could be reduced 5% only if the system is integrated with the vehicle cabin air conditioning system. The reason why we were not able to achieve the 20% reduction target is because of the natural decay of the battery cell due to the number of cycles. Perhaps newer battery chemistries that are not so sensitive to cycling would have more potential for reducing the battery size due to thermal issues.

25 ENERGY STORAGE↗

DOE OSTI2023

Development of a hardware-in-the-loop testbed for laboratory performance verification of flexible building equipment in typical commercial buildings

The goals of reducing energy costs, shifting electricity peaks, increasing the use of renewable energy, and enhancing the stability of the electric grid can be met in part by fully exploiting the energy flexibility potential of buildings and building equipment. The development of strategies that exploit these flexibilities could be facilitated by publicly available high-resolution datasets illustrating how control of HVAC systems in commercial buildings can be used in different climate zones to shape the energy use profile of a building for grid needs. This article presents the development and integration of a Hardware-In-the-Loop Flexible load Testbed (HILFT) that integrates physical HVAC systems with a simulated building model and simulated occupants with the goal of generating datasets to verify load flexibility of typical commercial buildings. Compared to simulation-only experiments, the hardware-in-the-loop approach captures the dynamics of the physical systems while also allowing efficient testing of various boundary conditions. The HILFT integration in this article is achieved through the co-simulation among various software environments including LabVIEW, MATLAB, and EnergyPlus. Although theoretically viable, such integration has encountered many real-world challenges, such as: 1) how to design the overall data infrastructure to ensure effective, robust, and efficient integration; 2) how to avoid closed-loop hunting between simulated and emulated variables; 3) how to quantify system response times and minimize system delays; and 4) how to assess the overall integration quality. Lessons-learned using the examples of an AHU-VAV system, an air-source heat pump system, and a water-source heat pump system are presented.

Chen, zhelun↗

DOE OSTI2026

Virtual refrigerant charge sensing algorithm for residential CO₂ heat pumps

Natural refrigerants are increasingly adopted in next-generation heat pump systems, among which CO₂ heat pumps have attracted significant attention. However, due to their high operating pressures, the leakage risk is higher, resulting in undercharge conditions and degraded heat pump performance. Thus, developing an accurate refrigerant charge level detection technique is necessary to guarantee safe and efficient operation. Although virtual refrigerant charge (VRC) level calculation algorithms for CO₂ heat pumps exist, they typically rely on empirically selected features without a systematic selection framework, leading to multicollinearity and potential overfitting, which limit their prediction accuracy and generalizability. To address these issues, this study proposes a VRC algorithm framework with a systematic feature selection method that identifies physically meaningful and statistically significant features, and is applied using a residential CO₂ heat pump as a case study. The method is extended from previous work on conventional refrigerants to account for charge behavior in CO₂ gas coolers. The selected features include gas cooler outlet density, evaporator pressure, and superheat temperature. The results demonstrate that the proposed feature selection method significantly improves prediction accuracy compared to existing VRC approaches. A relatively small training dataset (∼30 samples) is sufficient for feature identification and model development. The developed algorithm achieves less than 3% prediction error under both undercharge and overcharge conditions, representing reductions of 46.7% and 35.3% compared to two recent reference VRC algorithms for transcritical CO₂ heat pumps reported in the literature. The proposed algorithm and feature selection method enhance leakage detection capability, facilitate the deployment of CO₂ heat pump systems, and contribute to reduced energy waste and maintenance costs.

Guo, Fangzhou [Lawrence Berkeley National Laborato↗

DOE OSTI2014

Bio-Oil Separation and Stabilization by Supercritical Fluid Fractionation. 2014 Final Report

The objective of this project is to use supercritical fluids to separate and fractionate algal-based bio-oils into stable products that can be subsequently upgraded to produce drop-in renewable fuels. To accomplish this objective, algae was grown and thermochemically converted to bio-oils using hydrothermal liquefaction (HTL), pyrolysis, and catalytic pyrolysis. The bio-oils were separated into an extract and a raffinate using near-critical propane or carbon dioxide. The fractions were then subjected to thermal aging studies to determine if the extraction process had stabilized the products. It was found that the propane extract fraction was twice as stable as the parent catalytic pyrolysis bio-oils as measured by the change in viscosity after two weeks of accelerated aging at 80°C. Further, in-situ NMR aging studies found that the propane extract was chemically more stable than the parent bio-oil. Thus the milestone of stabilizing the product was met. A preliminary design of the extraction plant was prepared. The design was based on a depot scale plant processing 20,000,000 gallons per year of bio-oil. It was estimated that the capital costs for such a plant would be $8,700,000 with an operating cost of $3,500,000 per year. On a per gallon of product cost and a 10% annual rate of return, capital costs would represent $0.06 per gallon and operating costs would amount to $0.20 per gallon. Further, it was found that the energy required to run the process represented 6.2% of the energy available in the bio-oil, meeting the milestone of less than 20%. Life cycle analysis and greenhouse gas (GHG) emission analysis found that the energy for running the critical fluid separation process and the GHG emissions were minor compared to all the inputs to the overall well to pump system. For the well to pump system boundary, energetics in biofuel conversion are typically dominated by energy demands in the growth, dewater, and thermochemical process. Bio-oil stabilization by near critical propane extraction had minimal impact in the overall energetics of the process with NER contributions of 0.03. Based on the LCA, the overall conversion pathways were found to be energy intensive with a NER of about 2.3 and 1.2 for catalytic pyrolysis and HTL, respectively. GHG emissions for the catalytic pyrolysis process were greater than that of petroleum diesel at 210 g CO2 eq compared to 18.9 g CO2 eq. Microalgae bio-oil based diesel with thermochemical conversion through HTL meets renewable fuel standards with favorable emission reductions of -10.8 g CO2 eq. The importance of the outcomes is that the critical fluid extraction and stabilization process improved product stability and did so with minimal energy inputs and processing costs. The LCA and GHG emission calculations point toward the HTL pathway as the more favorable thermochemical route towards upgrading algae to bio-fuels. Since the quality of the HTL oil was significantly lower than that of the catalytic pyrolysis bio-oil, the next steps point toward improving the quality of the HTL oils from algae biomass and focusing the critical fluid stabilization on that bio-oil product.

09 BIOMASS FUELS↗

NASA NTRS1988

The Instrument Test Dewar (ITD): Testing satellite instruments at 1.5 K

The Instrument Test Dewar (ITD) is a cryogenic facility designed and built to test Cosmic Background Explorer (COBE) satellite instruments at 1.5 K. The facility provides a high vacuum and thermal environment with payload thermal, electrical and optical interfaces. There are two concentric vacuum spaces which are not hermitically sealed. The instrument vacuum space is 81.28 cm by 243.84 cm and is cooled by an LHe shroud. The guard vacuum space surrounds an LN2 shroud. There are two separate cryosorption pumping systems and a mechanical LHe pumping system. The data acquisition systems provide payload and housekeeping data. There have been various problems with the facility, and changes and improvements have been made to assure optimum test conditions. COBE instrument testing has been completed on structural, thermal model hardware and the protoflight units.

Milam, Laura J.↗

NASA NTRS2019

Novel concept for detection of a fluid flow fault in a pumped fluid heat rejection system

A pumped fluid heat rejection system (HRS) requires continuous flow of the working fluid to ensure that the components controlled by the HRS stay within their allowable temperature limits. An interruption of flow could result in violations of hardware qualification limits and mission failure. Some of these violations can happen within a few hours. Hence, quick detection of a flow fault to invoke mitigation measures is very critical. In typical pumped fluid HRS, dual or triple pumps are employed to switch the backup units in case the primary unit were to fail. The key metric for the selection of a fault detection system is that it should detect the fault much before the fault’s impact on the thermal health of the HRS controlled components is realized. A trade study was conducted to select such a system for the Europa Clipper Mission to Europa, a moon of Jupiter that is planned for a launch in 2023. Out of the several concepts studied, the most attractive one was a novel and simple concept that uses a low power film heater attached to a section of the HRS tubing. While the fluid flows at its nominal rate, the high thermal coupling of the flowing fluid leads to the tube being close to the fluid’s temperature. However, when the flow stops, the heater warms the small thermal mass of the tubing to a high temperature in a short span of time (~15 minutes). This large temperature rise would then imply that the flow must have stopped. This paper will describe the various concepts considered, the chosen concept, its implementation, and the results of developments tests to validate its performance.

Schmidt, Tyler↗

NASA NTRS1978

Installation package for integrated programmable electronic controller and hydronic subsystem - solar heating and cooling

A description is given of the Installation, Operation, and Maintenance Manual and information on the power panel and programmable microprocessor, a hydronic solar pump system and a hydronic heating hot water pumping system. These systems are integrated into various configurations for usages in solar energy management, control and monitoring, lighting control, data logging and other solar related applications.

Source record↗

NASA NTRS2014

The Vacuum-Compacted Regolith Gripping Mechanism and Unmanned Flights via Quad-Rotors

During the course of the Kennedy Space Center Summer Internship, two main experiments were performed: The Vacuum-Compacted Regolith Gripping Mechanism and Unmanned Flights via Quad-copters. The objectives of the Vacuum-Compacted Regolith Gripping Mechanism, often abbreviated as the Granular Gripper, are to exhibit Space Technology, such as a soft robotic hand, lift different apparatuses used to excavate regolith, and conserve energy while executing its intended task. The project is being conducted to test how much weight the Granular Gripper can hold. With the use of an Animatronic Robotic Hand, Arduino Uno, and other components, the system was calibrated before actually conducting the intended weight test. The maximum weight each finger could hold with the servos running, in the order of pinky, ring, middle, and index fingers, are as follows: 1.340N, 1.456 N, 0.9579 N, and 1.358 N. Using the small vacuum pump system, the maximum weight each finger could hold, in the same order, was: 4.076 N, 6.159 N, 5.454 N, and 4.052 N. The maximum torques on each of the fingers when the servos were running, in the same respective order, was: 0.0777 Nm, 0.0533 Nm, 0.0648 Nm, and 0.0532 Nm. The maximum torques on the individual fingers, when the small vacuum pump was in effect, in the same order as above, was: 0.2318 Nm, 0.3032 Nm, 0.2741 Nm, and 0.1618 Nm. In testing all the fingers with the servos running, the total weight was 5.112 N and the maximum torque on the all the fingers was 0.2515 Nm. However, when the small vacuum pump system was used, the total weight was 19.741 N and the maximum torque on the all the fingers was 0.9713 Nm. The conclusion that was drawn stated that using the small vacuum pump system proved nearly 4 times more effective when testing how much weigh the hand could hold. The resistance provided by the compacted sand in the glove allowed more weight to be held by the hand and glove. Also, when the servos turned off and the hand still retaining its position, energy is being saved because the vacuum created the same resistance the running servos did without using power. The Unmanned Flights via Quad-rotors are built because multi-rotor dynamics are an important starting point and fair analog for space craft control systems and they make good terrestrial development platforms for various aspects of control for space crafts. The project is being conducted to see what the thrust response is going to be when a pulse width modulation command is sent to the control system since the quad-rotors are PWM controlled. A simulation environment in constructed so that one can quickly iterate and test different designs such as control systems, PID control vs. LDR control, and state estimation. Using two DIY Quad Kits, APM 2.6, testing apparatus (called a data acquisition system) to test the quad-rotors, and a simulation program such as Simulink, two quad-rotors are built and controlled via a simulation program, which is designed to be as realistic as possible and not idealistic. Due to the quad-rotors not being completely built nor ready for testing, there are no results or conclusions to report.

Granular Gripper↗

DOE OSTI2021

Electrical Submersible Pumps: A System Modeling Approach for Power Quality Analysis With Variable Frequency Drives

This article proposes a high-level engineering guide to develop an integrated system model for power quality analysis in electrical submersible pump (ESP) applications with variable frequency drives (VFDs). Such analyses are troublesome in the industry due to the complexity of these systems. In this article, simple steps to perform system integration analyses of such arrangements, including torsional analysis, are developed. A simplified VFD-ESP model suitable for coupled electrical and mechanical analysis in steady state is proposed in all their configurations of practical interest. Such a model can be easily implemented in common simulation software, significantly reducing engineering efforts for implementation and analysis. The focus of the proposed model is the prediction of ESP failures that might result from a poor power quality caused by VFDs. Analytical expressions of different types of harmonics in these systems, as well as their accurate locations in the frequency domain, including their interharmonics and common-mode harmonics, are derived for this purpose. Further, the effectiveness of the proposed model is verified through offline and real-time hybrid simulation results. Finally, a comparison between simulation results obtained using the proposed model and measurements collected on a down-scale laboratory prototype is carried out to demonstrate the accuracy of the suggested modeling approach.

42 ENGINEERING↗

DOE OSTI2022

Numerical modeling and parametric study of a dual purpose underground thermal battery

We report integrating thermal energy storage with building energy systems can enable flexible building electric demands at buildings to help mitigate the mismatch between electricity supply and demand. A novel building heating and cooling system that integrates a dual-source heat pump with hybrid thermal storage named dual-purpose underground thermal battery (DPUTB) has been developed for reshaping building electric demands. The proposed DPUTB integrated geothermal heat pump system is an original innovation that enables Grid-interactive Energy Efficient buildings. This paper focuses on the study of the novel DPUTB. The DPUTB works as both a thermal storage tank (an inner tank) and a ground heat exchanger (an outer tank separated from the inner tank by the insulation material). High fidelity and computationally effective models are needed to predict the performance of the novel DPUTB. This study has developed a simplified dynamic model for the DPUTB according to heat transfer and energy conservation principles and validated it by using experimental data obtained from testing a small-scale DPUTB apparatus. A parametric study was conducted to identify a design that can achieve the target thermal storage performance of load shift and energy efficiency. The parametric study results show that the inner tank shell thermal conductivity and the phase change material's melting point are the two most influencing factors on the performance of the DPUTB. One single full-size DPUTB with the identified design could provide 1-ton cooling (3.51 kW) with the supply temperature lower than 11 °C for 4 hours in summer after being fully charged in 8 hours. The inner tank filled with phase change material is for cooling thermal storage as a latent tank in the design. However, its capacity can be as high as 60 MJ as a sensible water tank for heating storage in winter. In the future study, the DPUTB model will be incorporated into the dual-source heat pump system for evaluating the overall system performance of demand side management in the long term.

25 ENERGY STORAGE↗

DOE OSTI2016

Comparative Cooling Season Performance of Air Distribution Systems in Multistory Townhomes

IBACOS investigated the performance of a small-diameter high velocity heat pump system compared to a conventional system in a new construction triplex townhouse. A ductless heat pump system also was installed for comparison, but the homebuyer backed out because of aesthetic concerns about that system. In total, two buildings, having identical solar orientation and comprised of six townhomes, were monitored for comfort and energy performance. Results show that the small-diameter system provides more uniform temperatures from floor to floor in the three-story townhome. No clear energy consumption benefit was observed from either system. The builder is continuing to explore the small-diameter system as its new standard system to provide better comfort and indoor air quality. The homebuilder also explored the possibility of shifting its townhome product to meet the U.S. Department of Energy Challenge Home National Program Requirements. Ultimately, the builder decided that adoption of these practices would be too disruptive midstream in the construction cycle. However, the townhomes met the ENERGY STAR Version 3.0 program requirements.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2016

Comparative Cooling Season Performance of Air Distribution Systems in Multistory Townhomes

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2019

Hydrodynamic and Structural Response Modeling of a Prototype Floating Membrane Reservoir System for Pumped Storage Hydropower

Hydrodynamic, computational fluid dynamics, and finite-element modeling were performed for a novel floating membrane reservoir system design for closed-loop pumped storage hydropower application. The conceptual design, which is now protected under an invention disclosure with a patent pending, offers a potential low-cost, low-impact solution to address the high costs, long investment return periods, and environmental disruptions encountered with traditional pumped storage development while offering modularity to enable replication at many locations. Prior to physical tests on a prototype, this paper documents the response analysis and modeling completed to simulate hydraulic and structural performance under different reservoir deployment and alignment arrangements, evaluate system stability, and refine the conceptual design. The results indicate that the excitation frequency from vortex shedding is at least an order of magnitude lower than the water sloshing frequencies in the reservoir, the structural natural frequency of the entire reservoir, and the vibrational frequencies of the side membranes, although excitation frequencies from other sources could cause mechanical resonance under certain conditions. To control destabilizing effects and prevent rocking motion and vibration, the authors conclude that the design could be improved by including a support structure around the floating reservoir, which could also provide floating-membrane containment, improve safety, and facilitate vertical reservoir movement. These conclusions, based on hydrodynamic and structural response modeling, help define specifications for upcoming full-scale prototype construction, deployment, and testing. This study demonstrates standard modeling technique application to an innovative design for which similar applications have not been previously evaluated. As a result, the refined design is capable of improving the scalability and feasibility of pumped storage hydropower in the United States and will be considered for commercialization following prototype testing.

13 HYDRO ENERGY↗

DOE OSTI2015

DEVELOPMENT OF COLD CLIMATE HEAT PUMP USING TWO-STAGE COMPRESSION

This paper uses a well-regarded, hardware based heat pump system model to investigate a two-stage economizing cycle for cold climate heat pump applications. The two-stage compression cycle has two variable-speed compressors. The high stage compressor was modelled using a compressor map, and the low stage compressor was experimentally studied using calorimeter testing. A single-stage heat pump system was modelled as the baseline. The system performance predictions are compared between the two-stage and single-stage systems. Special considerations for designing a cold climate heat pump are addressed at both the system and component levels.

Cold Climate↗