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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Investigation of a high-temperature combination heat pump for lower-cost electrification in multifamily buildings

The development of space and water heating combination heat pumps capable of generating water temperatures high enough for convective heat emitters will enable more cost-effective and equitable decarbonization solutions for electrifying multifamily buildings. Here, in this paper, multifamily building models and a charge-sensitive mechanistic cycle model of a combination heat pump are developed, and the system performance is predicted based on the models. Unlike other state-of-the-art residential heat pumping equipment, the modeled combination heat pump using an economized, fluid-injected variable-speed compressor can achieve higher temperature lifts of 40° - 85°C, with lower installation costs and complexity. The model predicted heating coefficient of performance (COP h ) is 2.1 at an ambient temperature of -15°C with a high-temperature lift of nearly 85°C, and a seasonal coefficient of performance in heating mode (SCOP h ) ranges from 2 - 4 for different locations. The system shows 30% - 90% lower CO 2 eq emissions over a condensing gas boiler and 9% - 13% lower projected installation costs than two separate space and water heat pumping appliances.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1980

Solar hot water system installed at Day's Lodge, Atlanta, Georgia

The solar energy hot water system installed in the Days Inns of America, Inc., Atlanta, Georgia is described. This system provides for 81 percent of the total hot water demand. There are two separate systems, each serving one building of the lodge (total of 65 suites). The entire system contains only potable city water. The 1024 square feet of Grumman Sunstream Model 332 liquid flat plate collectors and the outside piping drain whenever the collector plates approach freezing or when power is interrupted. Solar heated water from the two above ground cement lined steel tanks (1000 gallon tank) is drawn into the electric Domestic Hot Water (DHW) tanks as hot water is drawn. Electric resistance units in the DHW tanks top off the solar heated water, if needed, to reach thermostat setting.

Source record↗
DOE OSTI2021

Double Deep Q-Networks for Optimizing Electricity Cost of a Water Heater

Electric water heaters represent 14% of the electricity consumption in the residential buildings and the cost associated with domestic water heating account for a good portion of the household expenses in the United States. In this context, intelligent control of water heaters gained a lot of research attention. In recent years, a significant number of intelligent water heater controllers, with various methods and intended uses, have been proposed. However, existing studies are mostly model-based approaches that require an accurate modelling of the water heater. Towards addressing this research gap, this paper presents a model-free reinforcement learning-based controller for a day-ahead price market. The controller aims to minimize the cost of domestic water heating while maintaining the user comfort. The results showed that the developed controller can help save energy cost while maintaining the temperatures within the desired comfort band.

Amasyali, Kadir↗
DOE OSTI2025

Hydronic Shell: An Affordable Solution for Multifamily Deep Energy Retrofit

Approximately 42% of multi-family buildings in the United States have do not have insulation as required by the building codes. Envelope retrofits of these buildings are needed to improve their thermal performance, provide thermal resilience, and enable a pathway to electrification of space heating systems. Hydronic shell (HS) is a retrofit technique where a stud wall layer is added to a masonry wall along with a convective coil and a fan coil unit fitted in the façade cavity which can provide both heating and cooling to the space. The HS system serves a dual purpose of 1) retrofitting the building envelope and 2) retrofitting the HVAC system and enabling electrification of space heating. The electrification of space heating is possible from the installation of a combination of hydronic system/fan coil unit system which uses a central heat pump as a source of heating water in the cavity between the existing wall and retrofit insulation layer. This study evaluates the performance of the HS system at varying outdoor conditions mimicked by a climate chamber and hot water supply temperature from a water bath. During the ramp-up period, the indoor chamber temperature could be increased from 66 ºF to 69.5 ºF within an hour using heating water at 120 ºF when the outdoor chamber temperature was at 0 ºF. When the indoor chamber temperature was maintained within a deadband, variation in cavity air temperature was mostly influenced by the duration when water was flowing through the cavity convector. It was seen from the testing that the hydronic system alone without use of fan in the system is able to maintain the space temperature at coldest outdoor condition used in the experiment (0 ºF) even at lowest hot water supply temperature chosen (90 ºF). During the ramp-down period, the fastest decline in temperature took 6.4 hours from temperature to drop from 69.6 ºF to 66 ºF which shows tremendous potential of thermal resilience and peak load shifting.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2026

COGIHTO: Comprehensive Geothermal Integrated HVAC Retrofits in Disadvantaged Communities

Geothermal heating and cooling (GHC) systems offer one of the most efficient approaches to provide space conditioning and water heating in buildings. Due to the relatively stable temperature of the ground year-round, these systems can provide an efficient solution to decarbonize heating systems. Yet this technology has faced limited market adoption due to its high first cost. This project seeks to address this barrier by designing a community GHC system at a public housing development in New York, taking advantage of load diversity (in terms of the timing and amount of heating / cooling used per person) that a larger community offers to reduce the size and thus first cost of a GHC system. Project success would result in societal benefit from reduced energy and fossil fuel use, reduced local emissions, and improved comfort, which would positively impact the health and well-being this community. This report presents the findings from Phase 1 project supported by the Department of Energy’s Geothermal Technologies Office and includes the technical design of a GHC at a public housing development in New York. To support the success of a potential deployment of a GHC system, the team conducted community engagement and prepared an assessment of the local workforce needs. The project team, led by EPRI, considered a subset of NYCHA housing developments that were previously identified by NYCHA as suitable for GHC retrofits. This report presents the site selection criteria the team developed and the overall score assigned to each of the eight developments considered. One site was selected for focus of the technical design: Stapleton Houses in Staten Island, a mid-size development with roughly 700 apartments across 6 buildings. The site has an existing hot water hydronic loop served by natural gas boilers for space heating and water heating. The technical design partner assessed baseline energy consumption at the site and established thermal models of the apartment buildings to assist in the design. The team considered several GHC system configurations and selected a hybrid geothermal design fed from water-source heat pumps with auxiliary gas boilers in a central plant. This design best leveraged the existing site configuration and minimized costs due to additional electrical infrastructure upgrades. The report also details the feedback received from community engagement efforts and the findings from the workforce needs assessment and workforce transition plan. Members of the site maintenance staff and the resident advisory council were interviewed for their input and feedback about both the site’s existing heating/cooling infrastructure and how a construction project would impact resident life. This feedback was taken into consideration when completing the geothermal system design. Research was conducted into existing workforce development opportunities available to NYCHA residents. A workforce development plan was established using information from NYCHA’s resident economic empowerment and sustainability group, along with training material and curriculum from the International Ground Source Heat Pump Association (IGSHPA).

15 GEOTHERMAL ENERGY↗
NASA NTRS2010

Recent Advances in Power Conversion and Heat Rejection Technology for Fission Surface Power

Under the Exploration Technology Development Program, the National Aeronautics and Space Administration (NASA) and the Department of Energy (DOE) are jointly developing Fission Surface Power (FSP) technology for possible use in human missions to the Moon and Mars. A preliminary reference concept was generated to guide FSP technology development. The concept consists of a liquid-metal-cooled reactor, Stirling power conversion, and water heat rejection, with Brayton power conversion as a backup option. The FSP project has begun risk reduction activities on some key components with the eventual goal of conducting an end-to-end, non-nuclear, integrated system test. Several power conversion and heat rejection hardware prototypes have been built and tested. These include multi-kilowatt Stirling and Brayton power conversion units, titanium-water heat pipes, and composite radiator panels.

Mason, Lee↗
NASA NTRS1988

Comparison of measured and modeled radiation, heat and water vapor fluxes: FIFE pilot study

The primary objectives of the 1985 study were to test the feasibility of using radio frequency receivers to collect data from automated weather stations and to evaluate the use of the data collected by the automated weather stations for modeling the fluxes of latent heat, sensible heat, and radiation over wheat. The model Cupid was used to calculate these fluxes which were compared with fluxes of these entities measured using micrometeorological techniques. The primary objectives of the 1986 study were to measure and model reflected and emitted radiation streams at a few locations within the First International Satellite Land-Surface Climatology Project Field Experiment (FIFE) site and to compare modeled and measured latent heat and sensible heat fluxes from the prairie vegetation.

Blad, Blaine L.↗
DOE OSTI2024

“Max-tech FHR”: What is the maximum technically achievable water delivery capacity from a single 120 V plug?

Electrifying water heating will require affordable, direct drop-in replacements for existing gas water heaters that meet consumer expectations for hot water delivery. For many replacement scenarios, affordability requires a replacement option with like-for-like physical product dimensions, and existing consumer expectations presume a large delivery capacity from a small water heater. This work explores the technical potential for hot water delivery capacity for a heat pump water heater (HPWH) powered from a common 120 V plug. Delivery capability in this work is quantified by two metrics: the First Hour Rating (FHR) defined in the Code of Federal Regulations, and a real-world draw profile that resulted in hot water runout during field studies of 120 V HPWHs. The work focuses on the common “tall-and-slim” gas water heater product category, with external product dimensions of 20 inch diameter and 60 inch height. Using a simulation model in DOE/ORNL Heat Pump Design Model, validated by experimental baseline testing of a commercially available 120 V HPWH model, several measures were evaluated to maximize the delivery capacity of a 120 V HPWH. The 120 V HPWH was constrained by 1) external product dimensions of 20 in diameter and 60 inch height, 2) electrical power of 1.5 kW (85% of the available power from a dedicated 120 V, 15 A circuit), and 3) commercially-available components. The measures implemented included a large compressor, a pumped loop with plate heat exchanger to maximize tank stratification, enlarged heat exchangers, and relatively thin insulation to maximize the water storage volume.

Gluesenkamp, Kyle↗
DOE OSTI2020

Method and apparatus for reduction of water re-evaporation in a dedicated dehumidifier/water heater

An apparatus that includes a refrigeration circuit that includes an evaporator, a first condenser and a compressor. The apparatus includes a refrigerant-water heat exchanger that includes a second condenser fluidly coupled to the refrigeration circuit. A control valve is operatively connected to the refrigeration circuit to direct flow of refrigerant through at least one of the first condenser during a dehumidification mode and the second condenser during a water heating mode. A damper is disposed on an upwind side of the evaporator, the damper being operable to reduce airflow across the evaporator during a ventilation mode.

42 ENGINEERING↗
DOE OSTI2021

Method and apparatus for reduction of water re-evaporation in a dedicated dehumidifier/water heater

An apparatus that includes a refrigeration circuit that includes an evaporator, a first condenser and a compressor. The apparatus includes a refrigerant-water heat exchanger that includes a second condenser fluidly coupled to the refrigeration circuit. A control valve is operatively connected to the refrigeration circuit to direct flow of refrigerant through at least one of the first condenser during a dehumidification mode and the second condenser during a water heating mode. A damper is disposed on an upwind side of the evaporator, the damper being operable to reduce airflow across the evaporator during a ventilation mode.

Uselton, Robert B.↗
DOE OSTI2023

A Propane Hydronic Heat Pump with Energy Storage

Propane is an environment-friendly refrigerant, having a 20-year GWP (global warming potential) of 0.072 and a 100-year GWP of 0.02, as compared to R-410A having a GWP > 2000. It has superior thermodynamic cycle performance and heat transfer characteristics. However, propane is classified as a A3 refrigerant, which is highly flammable, and not allowed to be used indoor if the system charge is higher than 150 grams. It is a challenge to use propane in residential applications requiring a rated capacity larger than 10 k Watts. A hydronic heat pump, i.e., containing propane in an outdoor unit and distributing the cooling and heating capacity through a hydronic coil to the indoor space addresses the flammability issue, while maintaining a high efficiency. We developed a hydronic heat pump with propane, it uses a two-stage compressor, a brazed plate indoor heat exchanger, and a microchannel outdoor heat exchanger. It achieves a rated cooling capacity larger than 10 k Watts, and a cooling SEER (cooling seasonal energy efficiency rating) > 16.0 (cooling seasonal COP > 4.7) and a heating HSPF (heating seasonal performance factor) > 9.5 (heating seasonal COP > 2.78), while requiring a system charge < 1200 grams. Additionally, the hydronic heat pump was evaluated in a laboratory water heating loop to heat a 50-gallon water tank in a full condensing mode. Experiments of heating the tank water from 58F(14.4°C) to 150F(65.6°C) were conducted under ambient temperatures from 17F(-8.3°C) to 75F(23.9°C), at the compressor high and low stages.

Shen, Bo↗
NASA NTRS1976

Development of a solar powered residential air conditioner (General optimization)

A commercially available 3-ton residential Lithium Bromide (LiBr) absorption air conditioner was modified for use with lower temperature solar heated water. The modification included removal of components such as the generator, concentration control chamber, liquid trap, and separator; and the addition of a Chrysler designed generator, an off-the-shelf LiBr-solution pump. The design goal of the modified unit was to operate with water as the heat-transfer fluid at a target temperature of 85 C (185 F), 29.4 C (85 F) cooling water inlet, producing 10.5 kW (3 tons) of cooling. Tests were performed on the system before and after modification to provide comparative data. At elevated temperatures (96 C, 205 F), the test results show that Lithium Bromide was carried into the condenser due to the extremely violent boiling and degraded the evaporator performance.

Lowen, D. J.↗
DOE OSTI2022

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

The demand profile management of electric end uses is vital research for utilities and policymakers planning greenhouse gas emission reductions. In this study, detailed laboratory research was conducted on the load shifting potential of 4 grid-connected HPWHs and one electric resistance water heaters (ERWH). The testing applied different CTA-2045 shed and critical peak command designs under three water draw profiles. Highly-controlled laboratory experiments were conducted in Florida. One of the four HPWHs was a prototype incorporating the new CTA-2045-B protocol feature allowing ‘advanced’ load-up above tank setpoint. A three-hour morning (6 – 9 AM) and four-hour evening curtailment (4 – 8 PM) were defined as the shed or critical peak periods reflecting high-value control periods for utility coincident load for system-wide electric demand reductions. Tests were performed under baseline conditions (no load shift) and under varied load-shifting schemes, including load up and advanced load up, ahead of shed and critical peak commands. Data were collected from December 2020 – February 2022 in the laboratory and compared with field experiments in Florida and the Pacific Northwest. Grid-connected HPWHs were found to reduce peak demand by up to 0.47 kW compared to uncontrolled HPWH units, depending on time of day, control scheme, draw profile, and temperature cluster. The load up strategy demonstrated the ability of all units to utilize heat pump mode for extended periods ahead of peak events. Demand reductions for the HPWHs were much larger when compared with the ERWH— up to 1.64 kW with large hot water draws in winter.

Fenaughty, Karen↗
DOE OSTI2020

Pre-Commercial Scale-Up of a Gas-Fired Absorption Heat Pump

The project sought to advance the maturity of SMTI’s 80 kBTU/hr residential space and water heating GAHP from the engineering prototype stage (TRL-7) to pre-production readiness by addressing manufacturing, balance of system design and installation, cost, reliability, and field application questions. As part of this project, the project team has: (1) Matured the design package for a commercially ready product (2) Demonstrated compliance with relevant ANSI standards (3) Completed manufacturing and assembly process specifications (4) Completed total production cost estimates and capital equipment requirements (5) Initiated component and system level reliability assessments (6) Completed a small field demonstration including measured performance, installation requirements and expected costs, and customer/key stakeholder feedback. (7) Completed a Techno-economic analysis for representative applications and climate zones, including justification for utility incentive programs. (8) Completed a market intelligence report. Scope of Work: A multi-faceted project was completed that included: (a) design for manufacturing tasks for both the sealed system and balance of system, (b) development and trial of key manufacturing processes and techniques, (c) evaluation of component and system level reliability, (d) exploration of make/buy decisions including impact on cost and required capital. Additionally, (e) installation and monitoring of a small number of field test units was completed to demonstrate energy savings and collect customer/installer feedback, and (f) a focused market research task was completed to explore potential barriers and improve market introduction plans. These tasks addressed many of the remaining technical risks regarding long-term reliability, verification of manufacturing cost estimates and identification of cost concerns, identify installation and balance of system design criteria necessary to achieve energy savings and installed cost goals, and identify market barriers and strategies prior to product market introduction.

03 NATURAL GAS↗
DOE OSTI2020

Water and heat: New constraints on the evolution of the CV chondrite parent body

This paper focuses on the post-accretion history of CV3 chondrites, through a combination of petrographic and mineralogical characterization, magnetic measurements, spectral (Raman and Infrared) and thermo-gravimetric analysis of 31 meteorites (including 7 falls, 21 Antarctic and 3 non-Antarctic finds) spanning a wide metamorphic range. We classify the 21 Antarctic chondrites and the Bukhara fall into the CV Red , CV OxA , and CV OxB subgroups. We establish quantitative parameters relevant for this sub-classification. In comparison to CV Ox , CV Red chondrites are characterized by (i) a lower abundance of matrix, (ii) a higher abundance of metal, (iii) the presence of Ni-poor sulfides. In comparison to CV OxB , CV OxA are characterized by (i) similar matrix abundance, (ii) a higher abundance of metal, (iii) the presence of metal almost exclusively under the form of awaruite, (iv) lower Ni content of sulfides, (v) lower magnetic susceptibility and saturation remanence. In this work, both CV Ox (CV OxA and CV OxB ) and CV Red experienced aqueous alteration, and contain oxyhydroxides and phyllosilicates. We show that the abundance of these hydrated secondary minerals observed today in individual CV chondrites decreases with their peak metamorphic temperature. This is interpreted either as partial dehydration of these secondary minerals or limited hydration due to the rapid exhaustion of the water reservoir during parent body thermal metamorphism. Moreover, the lower abundance of oxyhydroxides (that have a lower thermal stability than phyllosilicates and may in large part postdate the peak of thermal metamorphism) in more metamorphosed CV chondrites is interpreted as lower availability of aqueous fluids during retrograde metamorphism in these meteorites. Lastly, we show that in comparison to CV OxB , CV OxA are systematically (i) more metamorphosed, (ii) less hydrated, (iii) depleted in ferromagnetic minerals, (iv) but enriched in metal in the form of secondary awaruite. CV OxA may be thermally metamorphosed CV OxB . CV Red are significantly different from CV Ox (matrix abundances, alteration products, opaque minerals), but span the same wide metamorphic range. This could be indicative of a laterally heterogeneous CV parent body, or suggest the existence of distinct parent bodies for CV Ox and CV Red chondrites.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Comparative Analysis of Model Predictive Control and MPC-Informed Rule-Based Control for Thermal Storage Operation in Ultra-Low Temperature 4th Generation District Heating Networks

The integration of thermal storage and heat pumps in district heating networks (DHNs) can significantly enhance operational flexibility and energy efficiency; however, the practical deployment of advanced control strategies is often hindered by forecasting requirements and computational complexity. This study presents a comparative analysis of thermal storage control strategies in an ultra-low-temperature fourth-generation DHN, focusing on the development of a simplified rule-based control (RBC) explicitly informed by Model Predictive Control (MPC) behavior. The proposed methodology systematically analyzes the charging and discharging decisions of an MPC-controlled system under ideal forecasting conditions and extracts recurrent control patterns as a function of key system variables, including outdoor temperature, thermal demand, and electricity price. These patterns are translated into a set of structured time- and condition-based rules, resulting in an MPC-informed RBC that embeds predictive insights while preserving implementation simplicity and operational transparency. The approach is validated on a realistic mixed-use urban district in Denver, Colorado, USA, equipped with a centralized air-source heat pump, distributed water-to-water heat pumps, and a central thermal storage unit. Results show that the tuned RBC attains approximately 96% of ideal MPC economic performance (-27% of costs), preserves values of technical and environmental indicators (reduction only of 2-3%), and substantially reduces complexity. Sensitivity analyses further demonstrate the robustness of the RBC under varying operational conditions (i.e., ambient temperature, electricity price). Overall, the study demonstrates that MPC-informed rule-based control represents an effective trade-off between control performance and real-world applicability, enabling the integration of additional system components while maintaining simplicity, robustness, and ease of implementation.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗