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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Understanding Energy Impacts of Oversized Air Conditioners; NREL Highlights, Research & Development, NREL (National Renewable Energy Laboratory)

This NREL highlight describes a simulation-based study that analyzes the energy impacts of oversized residential air conditioners. Researchers found that, if parasitic power losses are minimal, there is very little increase in energy use for oversizing an air conditioner. The research demonstrates that new residential air conditioners can be sized primarily based on comfort considerations, because capacity typically has minimal impact on energy efficiency. The results of this research can be useful for contractors and homeowners when choosing a new air conditioner or heat pump during retrofits of existing homes. If the selected unit has a crankcase heater, performing proper load calculations to be sure the new unit is not oversized will help avoid excessive energy use.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

NREL's Water Power Software Makes a Splash; NREL Highlights, Research & Development, NREL (National Renewable Energy Laboratory)

WEC-Sim is a DOE-funded software tool being jointly developed by NREL and SNL. WEC-Sim computationally models wave energy converters (WEC), devices that generate electricity using movement of water systems such as oceans, rivers, etc. There is great potential for WECs to generate electricity, but as of yet, the industry has yet to establish a commercially viable concept. Modeling, design, and simulations tools are essential to the successful development of WECs. Commercial WEC modeling software tools can't be modified by the user. In contrast, WEC-Sim is a free, open-source, and flexible enough to be modified to meet the rapidly evolving needs of the WEC industry. By modeling the power generation performance and dynamic loads of WEC designs, WEC-Sim can help support the development of new WEC devices by optimizing designs for cost of energy and competitiveness. By being easily accessible, WEC-Sim promises to help level the playing field in the WEC industry. Importantly, WEC-Sim is also excellent at its job! In 2014, WEC-Sim was used in conjunction with NREL’s FAST modeling software to win a hydrodynamic modeling competition. WEC-Sim and FAST performed very well at predicting the motion of a test device in comparison to other modeling tools. The most recent version of WEC-Sim (v1.1) was released in April 2015.

16 TIDAL AND WAVE POWER↗
DOE OSTI2015

NREL Highlight: Truck Platooning Testing; NREL (National Renewable Energy Laboratory)

NREL's fleet test and evaluation team assesses the fuel savings potential of semi-automated truck platooning of line-haul sleeper cabs with modern aerodynamics. Platooning reduces aerodynamic drag by grouping vehicles together and safely decreasing the distance between them via electronic coupling, which allows multiple vehicles to accelerate or brake simultaneously. In 2014, the team conducted track testing of three SmartWay tractor - two platooned tractors and one control tractor—at varying steady-state speeds, following distances, and gross vehicle weights. While platooning improved fuel economy at all speeds, travel at 55 mph resulted in the best overall miles per gallon. The lead truck demonstrated fuel savings up to 5.3% while the trailing truck saved up to 9.7%. A number of conditions impact the savings attainable, including ambient temperature, distance between lead and trailing truck, and payload weight. Future studies may look at ways to optimize system fuel efficiency and emissions reductions.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2012

Technical Highlight: NREL Tests Integrated Heat Pump Water Heater Performance in Different Climates (Fact Sheet)

This technical highlight describes NREL tests to capture information about heat pump performance across a wide range of ambient conditions for five heat pump water heaters (HPWH). These water heaters have the potential to significantly reduce water heater energy use relative to traditional electric resistance water heaters. These tests have provided detailed performance data for these appliances, which have been used to evaluate the cost of saved energy as a function of climate. The performance of HPWHs is dependent on ambient air temperature and humidity and the logic controlling the heat pump and the backup resistance heaters. The laboratory tests were designed to measure each unit's performance across a range of air conditions and determine the specific logic controlling the two heat sources, which has a large effect on the comfort of the users and the energy efficiency of the system. Unlike other types of water heaters, HPWHs are both influenced by and have an effect on their surroundings. Since these effects are complex and different for virtually every house and climate region, creating an accurate HPWH model from the data gathered during the laboratory tests was a main goal of the project. Using the results from NREL's laboratory tests, such as the Coefficient of Performance (COP) curves for different air conditions as shown in Figure 1, an existing HPWH model is being modified to produce more accurate whole-house simulations. This will allow the interactions between the HPWH and the home's heating and cooling system to be evaluated in detail, for any climate region. Once these modeling capabilities are in place, a realistic cost-benefit analysis can be performed for a HPWH installation anywhere in the country. An accurate HPWH model will help to quantify the savings associated with installing a HPWH in the place of a standard electric water heater. In most locations, HPWHs are not yet a cost-effective alternative to natural gas water heaters. The detailed system performance maps that were developed by this testing program will be used to: (1) Target regions of the country that would benefit most from this technology; (2) Identify improvements in current systems to maximize homeowner cost savings; and (3) Explore opportunities for development of advanced hot water heating systems.

03 NATURAL GAS↗
DOE OSTI2012

Technical Highlight: NREL Delivers In-Home HVAC Efficiency Testing Solutions (Fact Sheet)

Researchers at the National Renewable Energy Laboratory (NREL) have recently developed two simple in-home efficiency test methods that can be used by technicians, researchers, or interested homeowners to verify the correct operation and energy efficiency of a home's air conditioning equipment. An efficiency validation method for mini-split heat pumps (MSHPs) - highly efficient refrigerant-based air conditioning and heating systems that permit room-by-room conditioning and control - will enable building researchers to easily explore the installed performance of this class of equipment. MSHPs are very popular overseas and are gaining market share in energy efficient home upgrades throughout the United States. Yet, because MSHPs have multiple variable-speed components that work in tandem, their performance is challenging to measure in a real home. NREL researchers developed a field evaluation method including test equipment, methods, and data analysis to determine the installed performance of this equipment in occupied homes. A field test was conducted to validate the method. When testing a home's operation, it is often important to simulate occupancy within an unoccupied home. That way, the researcher will know the actual usage profiles for heat and moisture generation; this removes the uncertainty associated with real occupants. The second test method details a standardized protocol for generating heat and moisture loads, to mimic occupants and their activities by using heaters and humidifiers. Realistic heat and moisture loads can be used to drive air conditioning systems, evaluate air distribution systems, and examine building enclosure technologies. These loads are drawn from the Building America House Simulation Protocols. Proper application of the method will result in better comparison between performance of the test home and its simulated analogue. This method is also validated by field testing. These test methods are now available in two technical reports. The methods can be used widely by the building research community to confirm proper operation of space conditioning equipment in homes, thereby improving thermal comfort, building health, and durability. National objectives for cost-effective energy savings in the residential sector can be met more quickly and with greater consistency.

14 SOLAR ENERGY↗
DOE OSTI2012

Technical Highlight: NREL Delivers In-Home HVAC Efficiency Testing Solutions

Researchers at the National Renewable Energy Laboratory (NREL) have recently developed two simple in-home efficiency test methods that can be used by technicians, researchers, or interested homeowners to verify the correct operation and energy efficiency of a home’s air conditioning equipment.

heating, ventilation, air conditioning↗
DOE OSTI2013

Realizing a Clean Energy Future: Highlights of NREL Analysis (Brochure)

Profound energy system transformation is underway. In Hawaiian mythology, Maui set out to lasso the sun in order to capture its energy. He succeeded. That may have been the most dramatic leap forward in clean energy systems that the world has known. Until now. Today, another profound transformation is underway. A combination of forces is taking us from a carbon-centric, inefficient energy system to one that draws from diverse energy sources - including the sun. NREL analysis is helping guide energy systems policy and investment decisions through this transformation. This brochure highlights NREL analysis accomplishments in the context of four thematic storylines.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Exploring Floatovoltaics: How Floating Solar PV Could Influence Our Changing Energy Landscape

In recent years, solar photovoltaic (PV) systems have popped up on bodies of water in more than a dozen countries around the world. Although U.S. adoption of floating solar PV, or “floatovoltaics,” has been limited, reservoir operations, water treatment facilities, residential communities, and other institutions are increasingly exploring the potential benefits of siting PV systems on man-made bodies of water. Along with helping reduce evaporation rates and algae growth, water-based siting of solar PV can lower system operating temperatures and reduce the costs of solar energy generation. In this video, National Renewable Energy Laboratory (NREL) researcher Alex Aznar highlights NREL’s ground-breaking assessment of floating solar PV’s potential to contribute significantly to the U.S. electric sector of the future.

14 SOLAR ENERGY↗
DOE OSTI2015

NREL Software Models Performance of Wind Plants (Fact Sheet)

This NREL Highlight is being developed for the 2015 February Alliance S&T Meeting, and describes NREL's Simulator for Offshore Wind Farm Applications (SOWFA) software in collaboration with Norway-based Statoil, to optimize layouts and controls of wind plants arrays.

17 WIND ENERGY↗
DOE OSTI2015

New Method to Stabilize Solar Water-Splitting Electrodes (Fact Sheet)

This NREL Highlight is being produced for the 2015 February Alliance S&T Board meeting and describes a two-step modification of high-efficiency III-V photoelectrolysis materials that provide corrosion protection for hundreds of hours without sacrificing conversion efficiency.

14 SOLAR ENERGY↗