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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on AgTe by Materials Project

AgTe crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to three Ag1+ and four Te1- atoms. There are a spread of Ag–Ag bond distances ranging from 3.01–3.09 Å. There are a spread of Ag–Te bond distances ranging from 2.83–3.14 Å. In the second Ag1+ site, Ag1+ is bonded in a 3-coordinate geometry to two equivalent Ag1+ and four Te1- atoms. There are a spread of Ag–Te bond distances ranging from 2.83–3.23 Å. In the third Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to two equivalent Ag1+ and four Te1- atoms. There are a spread of Ag–Te bond distances ranging from 2.87–2.98 Å. There are three inequivalent Te1- sites. In the first Te1- site, Te1- is bonded in a 5-coordinate geometry to four Ag1+ and one Te1- atom. The Te–Te bond length is 2.90 Å. In the second Te1- site, Te1- is bonded in a 1-coordinate geometry to one Ag1+ and two equivalent Te1- atoms. In the third Te1- site, Te1- is bonded in a 7-coordinate geometry to seven Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er7(AgTe)2 by Materials Project

Er7(AgTe)2 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are four inequivalent Er sites. In the first Er site, Er is bonded in a 4-coordinate geometry to two equivalent Ag and two equivalent Te atoms. Both Er–Ag bond lengths are 3.01 Å. Both Er–Te bond lengths are 3.10 Å. In the second Er site, Er is bonded in a 3-coordinate geometry to three Te atoms. There are two shorter (3.24 Å) and one longer (3.28 Å) Er–Te bond lengths. In the third Er site, Er is bonded to two equivalent Ag and three Te atoms to form a mixture of distorted edge, corner, and face-sharing ErAg2Te3 trigonal bipyramids. Both Er–Ag bond lengths are 2.97 Å. There are one shorter (3.08 Å) and two longer (3.15 Å) Er–Te bond lengths. In the fourth Er site, Er is bonded in a 4-coordinate geometry to three equivalent Ag and one Te atom. There are two shorter (2.91 Å) and one longer (3.18 Å) Er–Ag bond lengths. The Er–Te bond length is 3.13 Å. Ag is bonded in a 7-coordinate geometry to seven Er atoms. There are two inequivalent Te sites. In the first Te site, Te is bonded in a 8-coordinate geometry to eight Er atoms. In the second Te site, Te is bonded to seven Er atoms to form distorted edge-sharing TeEr7 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(AgTe)2 by Materials Project

BaAg2Te2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ba2+ is bonded in a 7-coordinate geometry to seven Te2- atoms. There are a spread of Ba–Te bond distances ranging from 3.50–3.78 Å. There are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 6-coordinate geometry to two equivalent Ag1+ and four Te2- atoms. Both Ag–Ag bond lengths are 2.94 Å. There are a spread of Ag–Te bond distances ranging from 2.87–2.95 Å. In the second Ag1+ site, Ag1+ is bonded to four Te2- atoms to form a mixture of corner and edge-sharing AgTe4 tetrahedra. There are a spread of Ag–Te bond distances ranging from 2.82–2.96 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to three equivalent Ba2+ and four Ag1+ atoms to form a mixture of distorted corner and edge-sharing TeBa3Ag4 pentagonal bipyramids. In the second Te2- site, Te2- is bonded in a 8-coordinate geometry to four equivalent Ba2+ and four Ag1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A Numerical Study on the Energy Performance of a Novel Furnace With Acidic Gas Trap Absorbers

Natural gas furnaces are widely used in US residential and commercial building markets. An important issue for natural gas furnaces is serious corrosion and fouling problems caused by acidic gas, such as SOx. An advanced adsorption technology based on acidic gas trap (AGT) absorbers offers the possibility to remove SOx acidic gas from natural gas furnaces with high efficiency and low cost, thereby enabling the development of condensing furnaces without the use of expensive corrosion resistant materials in the heat exchanger. A three-dimensional (3D) computational fluid dynamics (CFD) model has been developed to evaluate the heat transfer performance of a furnace with AGT absorbers and to compare it with a baseline conventional furnace without the AGT. Moreover, an axisymmetric model has been built focusing on the absorbing process in the AGT. The baseline conventional furnace used for the study is a commercial condensing furnace (Rheem 92% AFUE 84,000 BTU Multi-Position Gas Furnace). This furnace was completely disassembled, and the dimensions of each part were carefully measured and used to build a detailed CFD model. A model representing the new furnace, incorporating the AGT absorbers, was developed by adding the AGT system to the conventional furnace model. For the CFD analysis, a mixture model was employed to characterize the heat and mass transfer during the condensing process in the furnace while considering three components—air, water vapor and liquid water. Condensation takes place in the condensing heat exchanger, where water vapor changes phase to liquid water, and the latent heat is thus used in the furnace for useful heating. The simulation results characterize the energy performance of both the conventional furnace and the novel furnace with AGT absorbers, as well as the reactive processing in the AGT. These results provide insightful guidance for the development of the AGT absorber-based furnace from the perspective of its energy performance and will be used to further optimize this novel furnace design.

Laclair, Tim↗
DOE OSTI2021

Clean and High-Efficiency Natural Gas Furnace with Advanced Acidic Gas Trap Technology

Ccurrent natural gas condensing furnaces generate substantial acidic condensate and SOx/NOx/CO/HC/methane emissions, causing long-term environment issues related to air, water and soil. Acidic condensate occurs when flue gases within the furnaces cool down below the dew points of acidic gases, which upon condensation, combine with water vapor to produce acidic solutions. The acidic condensate causes serious corrosion and fouling problems in natural gas condensing furnaces. This paper presents a novel solution to use an advanced adsorption technology based on monolithic acidic gas trap (AGT) adsorbers for SOx trapping, NOx redox, and formic acid/CO/HC/methane oxidation, enabling a new natural gas furnace with utra-clean flue gas and neutral condensate. When the AGT adsorber is appropriately integrated with natural gas furnaces, the acidic gases of SOx, NOx and formic gas/CO/HC will be continuously adsorbed, redoxed or oxidized, respectively, from the flue gas during a regular heating season, except for occasional regeneration activities for SOx trapping. In the paper, we present results from a prototype furnace employing the novel AGT component, which enables a pH of the condensate =7, NOx emissions of 1-2 nanograms/joule and an annual fuel utilization efficiency (AFUE) of 96%, providing a cost-effective technology for condensing furnaces that is eco-friendly to the environment.

Gao, Zhiming↗
DOE OSTI2020

Materials Data on AgTe2Au by Materials Project

AuTeAgTe crystallizes in the orthorhombic Pmma space group. The structure is one-dimensional and consists of one AgTe ribbon oriented in the (0, 0, 1) direction and one AuTe ribbon oriented in the (0, 0, 1) direction. In the AgTe ribbon, Ag1+ is bonded in a distorted linear geometry to two equivalent Te2- atoms. Both Ag–Te bond lengths are 2.72 Å. Te2- is bonded in a 2-coordinate geometry to two equivalent Ag1+ atoms. In the AuTe ribbon, Au3+ is bonded in a distorted linear geometry to two equivalent Te2- atoms. Both Au–Te bond lengths are 2.71 Å. Te2- is bonded in a distorted water-like geometry to two equivalent Au3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Monolithic gas trap adsorber for high efficiency, cost effective, low-emission condensing furnace

An improved method and system for treating flue gases from a natural gas furnace are provided. The method and system include an acidic gas trap (AGT) adsorber which enables the continuous adsorption and storage of SOx, NOx redox, and formic acid/CO/HC/CH 4 oxidation, with a negligible pressure drop. The AGT adsorber includes a catalyst coating having a nanotube structure (e.g., a uniform nanostructure forest coating) or a uniform porous nanostructure of various low-cost oxides through scalable low temperature solution processes, including oxides of Ti, Cu, Ba, Mn, Zr, Zn, Sr, Ca, Li, K, Na, Al, or Ce.

Gao, Zhiming↗