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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 OSTI2022

International review of market trends, technologies and policies for commercial refrigeration equipment and implications for China

This report reviews the latest global and China-specific market trends as well as latest technology and policy trends related to commercial refrigeration equipment, with emphasis on refrigerated display cabinets. Section 2 reviews the global and China market trends for commercial refrigeration equipment. Section 3 presents the latest technology options for improving energy performance and compares global Best Available Technologies (BAT) to regional and China-specific baselines, and discusses low-GWP refrigerant options for commercial refrigeration equipment. Section 4 reviews global energy efficiency standards and labeling programs, and compares international efficiency standard requirements with China’s proposed and existing standard requirements. Section 5 ends with a review of key findings and conclusions.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

Driving the Shift to Energy-Efficient and Climate-Responsible Commercial Refrigeration Equipment in Chile

This report provides an overview of global and Chile-specific market trends, technological advancements, and policy developments related to commercial refrigeration equipment, with an emphasis on refrigerated display cabinets. Section 2 examines CRE market trends at the global and Chilean levels. Section 3 presents CRE energy consumption and the latest technological options for improving energy performance. It also discusses low global warming potential (GWP)1 refrigerant options for CRE. Section 4 provides a cost-effectiveness analysis. Section 5 reviews other regional energy efficiency standards and labeling programs and offers potential standard requirements for Chile. Section 6 concludes the report by summarizing key findings and conclusions. Finally, Appendix A provides detailed guidelines intended as a starting point to inform policies and programmes.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

A Modeling-Based Flammable Risk Treatment of Refrigerant Leakage from a Commercial R-290 Refrigeration Machine

Because of serious concerns about global warming, manufacturers have started phasing out high global warming potential (GWP) refrigerants in commercial refrigeration equipment (e.g., R-134a). As a potential replacement, propane (R-290) is an environmentally friendly refrigerant for commercial refrigeration equipment because its GWP is only three. However, propane is flammable and is therefore classified as a Class A3 refrigerant per ASHRAE Standards, so safety is a very important consideration when propane-based equipment is designed and deployed in buildings. In the event of a refrigerant leak, flammability of the refrigerant depends on the refrigerant’s local concentration, which is highly affected by the indoor air environment, including temperature and air flow. In this study, a ventilation system attached to a commercial R-290 refrigeration device was designed to eliminate the flammability risk. Moreover, a computational fluid dynamics (CFD) model was developed to investigate the refrigerant leak, thereby evaluating effects of the ventilation system. The CFD model can visualize the flammable zones owing to the leak.

42 ENGINEERING↗
DOE OSTI2022

Energy-efficient building technologies

Buildings consume one-third of the total final energy produced on the globe and are responsible for almost 40 percent of total carbon dioxide generation annually. The latest carbon dioxide burden of buildings approached 10 Gigatons in the year 2019. Energy-efficient building technologies are necessary to address the climate change induced by greenhouse gases and fulfill the growth in demand and continuously depleting energy reserves. To meet the net-zero carbon footprint goals, sustainable, renewable energy resources, efficient building technologies, and demand management strategies are needed. Achieving zero emissions will require buildings to be equipped with energy-efficient technologies while completely avoiding on-site fossil fuel consumption and being only powered by renewable energy. In this context, this chapter provides an overview of various building technologies, including envelopes, materials, equipment, appliances, and integration concepts, which will play a significant role in lowering the overall energy consumption in both existing building stock and new buildings. Specifically, the following areas are discussed in detail: emerging building envelope designs, thermal comfort and refrigeration equipment, bridging technologies for improved energy efficiency in the ongoing energy transition, hybrid renewable (photovoltaic) configurations, energy storage technologies, miscellaneous appliances, refrigerants, and renewable fuels. The influence of key design and operating characteristics on annual carbon footprint is presented.

Cheekatamarla, Praveen↗
DOE OSTI2023

A first test of CUPID prototypal light detectors with NTD-Ge sensors in a pulse-tube cryostat

CUPID is a next-generation bolometric experiment aiming at searching for neutrinoless double-beta decay with ~250 kg of isotopic mass of 100 Mo. It will operate at ~10 mK in a cryostat currently hosting a similar-scale bolometric array for the CUORE experiment at the Gran Sasso National Laboratory (Italy). CUPID will be based on large-volume scintillating bolometers consisting of 100 Mo-enriched Li 2 MoO 4 crystals, facing thin Ge-wafer-based bolometric light detectors. In the CUPID design, the detector structure is novel and needs to be validated. In particular, the CUORE cryostat presents a high level of mechanical vibrations due to the use of pulse tubes and the effect of vibrations on the detector performance must be investigated. In this paper we report the first test of the CUPID-design bolometric light detectors with NTD-Ge sensors in a dilution refrigerator equipped with a pulse tube in an above-ground lab. Light detectors are characterized in terms of sensitivity, energy resolution, pulse time constants, and noise power spectrum. Despite the challenging noisy environment due to pulse-tube-induced vibrations, we demonstrate that all the four tested light detectors comply with the CUPID goal in terms of intrinsic energy resolution of 100 eV RMS baseline noise. Indeed, we have measured 70–90 eV RMS for the four devices, which show an excellent reproducibility. We have also obtained high energy resolutions at the 356 keV line from a 133 Ba source, as good as Ge semiconductor γ detectors in this energy range.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Experimental Evaluation of a Microchannel Condenser for R600a Domestic Refrigerators

Domestic refrigerators are among the most common household appliances, accounting for approximately 4% of total household energy consumption, which is higher than that of clothes dryers, lighting, or cooking appliances. With nearly 13 million new domestic refrigerators sold annually, even marginal improvements in their energy performance can yield significant reductions in overall energy demand and cost. This study focuses on enhancing the performance of domestic refrigerators using R600a as the refrigerant. Most domestic refrigerators currently employ wire-and-tube condensers, which are bulky and require a larger refrigerant charge. Given that R600a is classified as an A3 flammable refrigerant under ASHRAE standards, minimizing the system charge while maintaining or improving performance is critical. To address this, a compact and light weight single-pass serpentine microchannel heat exchanger (made of aluminum) was adopted as a condenser, replacing the conventional wire-and-tube configuration. The modified system was experimentally tested according to AHAM test standards, and charge optimization was performed. The results demonstrated that the refrigerator equipped with the microchannel condenser achieved a 5.3% reduction in energy consumption compared to the baseline configuration with wire-and-tube condenser.

Murugan, Muneeshwaran [ORNL] (ORCID:00000003340352↗
DOE OSTI2024

Benefits and challenges in deployment of low global warming potential R290 refrigerant for room air conditioning equipment in California

High global warming potential gases (“high GWP”) are the fastest growing sector of greenhouse gas emissions in the world and in California and are primarily used as refrigerant gases in refrigeration and cooling equipment. Hydrofluorocarbons (HFCs) refrigerants are the dominant type of high GWP gases with GWP values thousands of times larger than CO 2 on a 100-year timescale. Refrigerant-grade propane (“R290”) has a very low GWP (GWP = 3.3) with good thermodynamic properties and good cooling equipment performance but the flammability of any leaked refrigerant makes equipment design, handling, and maintenance critical factors to manage. This paper focuses on the potential climate benefits and costs of transitioning to R290 refrigerant in small room air conditioning (AC) units, specifically window AC, packaged terminal AC/heat pumps (PTAC/PTHP), and mini-split heat pumps. Overall climate impact for a transition to all three types of air conditioning units in the 2022–2051 timeframe is found to be from 15 to 64 million metric tons of greenhouse gas (GHG) savings in California with a cost of saved CO 2 eq that ranges from $14.50 per ton of CO 2 eq saved to -$50.30 per ton of CO 2 eq saved (net savings) depending on whether the baseline refrigerant is R32 or R410A and depending on the relative energy efficiency for R290 units compared to baseline units.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

A NUMERICAL STUDY OF REFRIGERANT LEAKAGE FROM A PROPANE-BASED REFRIGERATION SYSTEM

Low Global Warming Potential (GWP) refrigerants, e.g. Propane (R290) (GWP = 3) and R1234yf (GWP = 4), are becoming a popular choice among refrigeration and HVAC systems, such as vending machines and air conditioning. However, most of Low GWP refrigerants are flammable (ASHRAE class A2 or A3), so safety is a very important consideration when designing and deploying low GWP refrigerants-based equipment in buildings. In the event of a refrigerant leak, the flammability of low GWP refrigerants depends on the local concentration of the refrigerant within the vicinity of the leak. In addition, the low GWP refrigerants concentration is affected by the indoor air environment, such as air flow rate and temperature. In the present study, a computational fluid dynamics (CFD) model is developed to model the flow and temperature of air surrounding a propane-based refrigeration system, as well as the concentration of leaked low GWP refrigerants surrounding the refrigeration system. The model results reveal the concentration distribution of low GWP refrigerants within the building, and as a result, the flammable regions within the building can be identified. Moreover, different ventilation layouts will be tested using the model to improve the design of ventilation. The numerical model can assist in the design of ventilation systems to minimize flammable regions within buildings due to leakage of flammable refrigerants.

Zhang, Mingkan↗
DOE OSTI2023

Liquid Air Combined Cycle TM for Power and Storage

Liquid Air Combined Cycle (LACC) is a hybrid liquid air energy storage (LAES) system combining energy storage with a combustion turbine to enable large-scale, long-duration energy storage (LDES) while reducing fuel intensity compared to the current state-of-the-art. The LACC technical approach employs proven equipment (cryogenic refrigeration, storage, tanks, pumps, gas turbines, exhaust heat recovery equipment, and turbines) to limit technical risk to a novel organic Rankine cycle (ORC), which was evaluated during this project and found to be feasible. Moreover, LACC storage is safe and relatively compact, to facilitate siting close to loads and within metropolitan regions. The air storage medium is freely available and eliminates supply chain constraints. LACC uses cryogenic air as a storage medium and a gas turbine as the source of heat to drive the discharge process. LACC is distinguished from other LAES technologies by several factors. The charge and discharge processes are decoupled so that cryogenic liquid air is the only storage medium. Other systems also store the higher temperature thermal energy from the liquefaction process in an additional medium. Subsequently, LACC focuses on maximization of the discharge energy and power. LACC also permits the use of commercially available cryogenic refrigeration and storage technologies to increase competition. This project identified product requirements to support market entry and commercialization of the LACC in modular units of approximately 117 MW, each drawing liquid air from customary cryogenic storage tanks capable of storing 75 GWh of dispatchable energy, more than pumped storage hydro or compressed air energy storage technologies. An economic analysis identified the specific liquid air consumption (quantity of liquid air per unit of discharge energy) as a critical parameter. Minimizing the air consumption reduces the specific capital cost ($\$ $/kW) for charging and discharging equipment by reducing the size of piping and turbomachinery. Likewise, the specific cost of energy capacity ($\$ $/kWh) is reduced by increasing the energy deliverable from a given size tank. The cycle was analyzed to identify the optimal equipment selection and operating conditions, which in turn were combined with quotes and cost estimates to calculate the cost of energy from an LACC system. A substantial effort was focused on the ORC, which draws low-temperature heat from the gas turbine exhaust and condenses at low temperature using the cryogenic liquid air as a heat sink. Alternative turbomachinery arrangements were evaluated for feasibility and cost. A technology maturation plan lays out a low-risk approach to development of the novel ORC components and demonstration of LACC technology at pilot scale.

25 ENERGY STORAGE↗
DOE OSTI2022

Low-GWP Refrigerants Status and Outlook

Refrigeration - including air conditioning (AC) – contributes substantially to the modern life of the 21st century and its economy. The food cold chain, air conditioning, healthcare and energy are examples of sectors for which refrigeration is indispensable. About 5 billion refrigeration systems – of different types and sizes– operate worldwide in different applications [1]. The dominant share of equipment providing refrigeration operate on the vapor-compression-cycle principle and use fluorocarbon refrigerants. Concerns about the environmental safety have become the driving force for refrigerant changes within the last 35 years. The phased-out schedule of stratospheric-ozone-depleting fluids was first formulated by the Montreal Protocol (MP) in 1987 and was made more stringent during the follow-up international meetings [2]. The affected chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants were largely replaced by hydrofluorocarbons (HFCs).The 2016 Kigali Amendment to the MP [3] responses to the concerns about the Earth climate change. The refrigeration and AC sectors are attributed with about 7.8 % of global greenhouse gas emissions [4]. This contribution comes in the form of direct effect, which is related to refrigerant emissions from refrigeration systems (37 %), and in the form of indirect effect, which is related to CO2 emissions from fossil fuel power plants producing electricity to power refrigeration systems (63 %) [4]. The Kigali Amendment aims at reducing the direct effect. The effect a given molecule has on the climate change is quantified in a simplified manner by its Global Warming Potential (GWP), a relative index referencing the effect produced to that of the same mass of carbon dioxide released to the atmosphere. By definition, GWP of carbon dioxide is equal to one.While HFC refrigerants have on average a lower GWP than the CFCs and HCFCs they replaced, they are still potent greenhouse gases (GHGs). The Kigali Amendment phases down the use of HFCs by imposing a schedule for reducing a weighted GWP value to be implemented by a country through the year 2047 (Figure 1). It provides four paths depending on the country location and category assigned in the MP, and also prescribes a method for establishing the baseline consumption used for calculating GWP reductions. For developing countries, it is expected to bring the weighed GWP across all refrigeration applications down to about 300 from the baseline value of about 2000. The implementation of Kigali Amendment aims at reducing the future warming due to HFCs from the range of 0.3 °C to 0.5 °C to less than 0.1 °C [5]. While this reduction may seem to be small, it must be viewed in the context of the 2015 Paris Agreement [6], which calls for holding global warming to well below 2 °C and pursuing to limit global warming to 1.5 °C relative to pre-industrial levels [6]. Considering that average global temperatures reached 1 °C above pre-industrial levels for the first time in 2015 [7], the Earth is already within 1 °C of the “2 °C limit”.The low-GWP requirement narrows the pool of fluids that can be considered for application as a refrigerant [8]. This Informatory Note discusses low-GWP refrigerant options for major applications and presents their selection merits.

Yana Motta, Samuel↗
DOE OSTI2023

Experimental Evaluation of Refrigerant Leak Characteristics for Different HVAC&R Equipment Types–Phase 2

The US Department of Energy (DOE) Building Technology Office (BTO) and the Air-conditioning, Heating & Refrigeration Technology Institute (AHRTI) collaborated to sponsor an experimental study of refrigerant leak characteristics at Oak Ridge National Laboratory (ORNL); AHRTI project 9012. The project has been conducted in two phases with objectives to conduct refrigerant leak tests on several heating, ventilating, air-conditioning and refrigeration (HVAC&R) systems under operating conditions representative of actual applications to document the pressure decay rate and the mass flow rate of leaked refrigerant as a function of time. Phase 1 of the project ran from late 2017 to late 2018 with refrigerant leaks imposed on five systems and the collection of data to meet the project objectives. Systems chosen covered three air-conditioning (AC) applications (packaged terminal AC or PTAC, 3-ton residential split system AC, and 5-ton packaged rooftop AC) and two refrigeration applications (split system unit cooler, and standalone display case). AHRTI members donated the test systems used for the project. The systems were tested at two different leak rates (catastrophic high rate simulating full line break and a lower flow rate), two leak locations (high-pressure side and low-pressure side), and two operating conditions (compressor ON or OFF). Phase 1 results were summarized in a project report by Baxter, et al. (2019)1. The leak rates imposed in Phase 1 led to much more rapid charge releases than the more typical much slower rates seen in practice that would take days, weeks, or months to empty a system of its entire charge. For Phase 2, the project sponsors asked that the “higher” leak rate target a total charge release time of about 4 min. This was intended to represent a “reasonable” worst case release scenario to match the refrigerant leak rate assumption used in the International Electrotechnical Commission (IEC) standard IEC 60335-2-40 (2016 version [IEC 2016]. A charge release time of about 20–40 min (leak release rate 5 to 10 times lower than higher rate) was targeted for the “lower” leak rate. This report provides a summary of the Phase 2 effort. Two additional HVAC systems were selected for testing in this phase. First was a multi-split air-conditioning (MS-AC) system with one outdoor section and two indoor units and a nameplate refrigerant charge of 1.75 kg (3.86 lb.) of R-410A. The MS-AC was tested in cooling only or AC operation. Second was a split system heat pump coupled to two different representative supply duct systems (HP-duct) and a nameplate charge of 3.83 kg (8.44 lb.) of R-410A. This system was tested in both space heating and AC modes. As in Phase 1 of the project, all tests were conducted using R-410A.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

Optimization of R290 variable geometry heat exchangers

Air-to-refrigerant heat exchangers (HX) are vital components in Heating, Ventilating and Air Conditioning and Refrigeration (HVAC&R) equipment. Recent literature has proposed utilizing shape-optimized, non-round tubes to reduce component size and refrigerant charge, thus enabling the adoption of low-GWP natural refrigerants like R290. However, most designs are restricted to fixed tube configurations, limiting the overall performance potential. In this work, multi-objective optimization is used in a staged approach to develop variable geometry multi-pass air-to-R290 HXs with minimal volume and airside pressure drop. Non-round tubes are used throughout the domain and each pass may have different tube arrangements to maximize HX performance. Compared to conventional fin-tube HXs, the optimized designs demonstrate more than 60% reductions in envelope volume, 30% reductions in face area, and up to 24% reduction in airside pressure drop. Additionally, the refrigerant charge reduction was up to 64%, thus enabling safe use of flammable and mildly-flammable refrigerants.

42 ENGINEERING↗
DOE OSTI2023

Assessment of the Performance of Hydrofluoroolefins, Hydrochlorofluoroolefins, and Halogen-Free Foam Blowing Agents in Cellular Plastic Foams

Oak Ridge National Laboratory has conducted a literature search to identify relevant information available on alternative materials and technologies that are proposed for foam blowing agents applications. For comparison, similar information was collected for available hydrofluorocarbons (HFC), hydrofluoroolefin (HFO), and hydrochlorofluoroolefins (HCFO) materials. The publicly available literature was analyzed and assessed for technical accuracy for each alternative, and a gap analysis was conducted to understand if additional studies are required to fully assess the viability of an alternative. In assessing these alternatives, this project focused on relevant performance and safety attributes. The performance attributes collected include insulation value per unit thickness, which impacts energy usage of buildings and insulated equipment such as refrigerators. We also assessed the impact of blowing agents on foam mechanical properties and flammability characteristics, and the ability of current processing equipment and techniques to utilize these alternatives. Diffusion of blowing agents through foam cells and its impact on foam aging was also examined. The applications covered in this study are spray foam, boardstock, panels, and appliances. Some of the most relevant findings are summarized below.

36 MATERIALS SCIENCE↗
DOE OSTI2022

In Tube Condensation Heat Transfer and Pressure Drop for R454B and R32—Potential Replacements for R410A

The heating, ventilation and air conditioning (HVAC) industry in the United States seeks near-term alternative refrigerants to replace R-410A in unitary equipment. Two potential replacement refrigerants are R-454B and R-32. It is of interest to investigate the capability and accuracy of existing heat exchanger design methods when applied to these replacement refrigerants. To that end, this work presents empirical condensation quasi-local heat transfer coefficient and pressure drop data for R-454B and R-32. These data were obtained in a $\frac{3}{8}$ in. (9.52 mm) outside diameter (OD) smooth copper tube with a wall thickness of 0.032 in. (0.81 mm). The experimental variables and their ranges included refrigerant absolute pressure ( 1960 ≤ P a b s ≤ 3196 kPa), condensation temperature ( 35 ≤ T c o n d ≤ 50 °C), mass flux ( 100 ≤ G ≤ 200 kg m -2 s -1 ), vapor quality ( 0 ≤ x ≤ 1 ), and heat flux ( 32.9 ≤ q ″ ≤ 62.97 kW m -2 ). It was found that the heat transfer correlation developed by Cavallini et al. Cavallini et al. (2006) predicted the experimental condensation heat transfer data, for both R-454B and R-32, with the greatest accuracy. Using the Cavallini et al. correlation, it was found that the mean absolute percentage error (MAPE) was 10.5% and 15.1% for R-454B and R-32, respectively. Additionally, the pressure drop correlation developed by Friedel Friedel (1979) predicted the experimentally determined pressure gradient with a MAPE of 7.7% and 5.5% for R-454B and R-32, respectively. These results will assist the practicing thermal engineer to choose the most appropriate design correlation for these near-term replacement refrigerants.

42 ENGINEERING↗
DOE OSTI2025

Horizontal 1 K refrigerator with novel loading mechanism for polarized solid targets

We describe a helium evaporation refrigerator used to cool dynamically polarized proton and deuteron targets for electron-scattering experiments using the CEBAF Large Acceptance Spectrometer CLAS12 at Jefferson Lab. The geometry of the CLAS12 detector systems places severe design and construction constraints on the refrigerator and its ancillary equipment, resulting in a horizontal cryostat with a length of 4 m. The 16 cm 3 target samples, consisting of frozen ammonia (NH 3 or ND 3 ), are loaded at the upstream end of the cryostat and moved to the beam-interaction region using a novel transport mechanism. At this location they are cooled with superfluid helium and polarized via dynamic nuclear polarization at 1 K and 5 T. In this manner samples can be replaced and cooled to 1 K in about 30 minutes without disturbing any elements of the electron beam line or particle detection system. In conclusion, we estimate that this method saved 18 days of valuable beam time over the course of a recent, 88-day long experiment.

Evaporation refrigerator↗
DOE OSTI2025

Beam Commissioning Result of Polarized Target at SpinQuest

SpinQuest is a fixed-target experiment at Fermilab to measure the Drell-Yan process using transversely polarized NH$_3$ and ND$_3$ targets and unpolarized 120-GeV proton beam. In the Drell-Yan process, a quark in one scattering hadron and an anti-quark in the other hadron annihilate into a virtual photon and then decay into a muon (lepton) pair. The angular distribution of final-state muon pairs with respect to the target polarization is sensitive to the Sivers function of light antiquarks in the nucleon, which is one of the eight Transverse Momentum Dependent (TMD) parton distribution functions. The intensity of the proton beam is as high as $10^{12}$ protons/second, in order to accumulate the required statistics of Drell-Yan events. The polarized target system at SpinQuest has been carefully designed to accommodate such a high beam intensity. It is equipped with an evaporation refrigerator with a cooling power of around 5 W at 1 K. The target temperature is maintained at 1 K even under heat load caused by the proton beam and the DNP microwave. The target system and the spectrometer were commissioned with the proton beam from May through July 2024. The experimental setup of SpinQuest and the performance of the target system during the beam commissioning is reported.

Nakano, Kenichi [Virginia U.]↗