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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Effectiveness of large booms as nutation dampers for spin stabilized spacecraft

The issue of using long slender booms as pendulous nutation damping devices on spinning aircraft is discussed. Motivation comes from experience with the Galileo Spacecraft, whose magnetometer boom also serves as a passive nutation damper for the spacecraft. Performance analysis of a spacecraft system equipped with such systems are relatively insensitive to changes in the damping constant of the device. However, the size and arrangement of such a damper raises important questions concerning spacecraft stability in general.

Eke, F. O.↗
DOE OSTI2023

Improving Stability of Triple-Cation Perovskite Solar Cells under High-Temperature Operation

Metal halide perovskite photovoltaic performance required for commercial technology encompasses both efficiency and stability. Advances in both these parameters have recently been reported; however, these strategies are often difficult to directly compare due to differences in perovskite composition, device architecture, fabrication methods, and accelerated stressors applied in stability tests. In particular, it is found that there is a distinct lack of elevated temperature, operational (light and bias) stability data. Furthermore, significant testing is required to understand the interactions when combinations are used (e.g., additives used with posttreatments). Herein, individual and combined additive, posttreatment, and contact layer strategies from recent literature reports under standardized operational stability tests of p-i-n CsMAFA perovskites at 70 degrees C are evaluated. Through analysis of over 1000 devices, it is concluded that the hole-transport layer (HTL) is the most significant component impacting elevated temperature operational stability. This analysis motivates future development of high-performance HTLs.

14 SOLAR ENERGY↗
DOE OSTI2025

Field-free switching of perpendicular magnetization in a ferrimagnetic insulator with spin reorientation transition

Writing magnetic bits through spin-orbit torque (SOT) switching is promising for fast and efficient magnetic random-access memory devices. While SOT switching of out-of-plane (OOP) magnetized states requires lateral symmetry breaking, in-plane (IP) magnetized states suffer from low storage density. Here, we demonstrate a field-free switching scheme using a 5-nanometer europium iron garnet film grown with a (110) orientation that shows a spin reorientation transition from OOP to IP above room temperature. This scheme combines the benefits of high-density storage in the OOP states at room temperature and the efficient field-free SOT switching in the IP states at elevated temperatures. While conventional switching of OOP bits faces the dilemma that high OOP anisotropy is required to improve bit stability and low OOP anisotropy is required to lower switching current density, this scheme disentangles this interdependence, allowing for low switching currents to be possible without sacrificing the bit stability, offering opportunities for future memory devices.

Science & Technology - Other Topics↗
NASA NTRS2014

Materials International Space Station Experiment (MISSE): Overview, Accomplishments and Future Needs

Materials and devices used on the exterior of spacecraft in low Earth orbit (LEO) are subjected to environmental threats that can cause degradation in material properties, possibly threatening spacecraft mission success. These threats include: atomic oxygen (AO), ultraviolet and x-ray radiation, charged particle radiation, temperature extremes and thermal cycling, micrometeoroid and debris impacts, and contamination. Space environmental threats vary greatly based on spacecraft materials, thicknesses and stress levels, and the mission environment and duration. For more than a decade the Materials International Space Station Experiment (MISSE) has enabled the study of the long duration environmental durability of spacecraft materials in the LEO environment. The overall objective of MISSE is to test the stability and durability of materials and devices in the space environment in order to gain valuable knowledge on the performance of materials in space, as well as to enable lifetime predictions of new materials that may be used in future space flight. MISSE is a series of materials flight experiments, which are attached to the exterior of the International Space Station (ISS). Individual experiments were loaded onto suitcase-like trays, called Passive Experiment Containers (PECs). The PECs were transported to the ISS in the Space Shuttle cargo bay and attached to, and removed from, the ISS during extravehicular activities (EVAs). The PECs were retrieved after one or more years of space exposure and returned to Earth enabling post-flight experiment evaluation. MISSE is a multi-organization project with participants from the National Aeronautics and Space Administration (NASA), the Department of Defense (DoD), industry and academia. MISSE has provided a platform for environmental durability studies for thousands of samples and numerous devices, and it has produced many tangible impacts. Ten PECs (and one smaller tray) have been flown, representing MISSE 1 through MISSE 8, yielding long-duration space environmental performance and durability data that enable material validation, processing recertification and space qualification; improved predictions of materials and component lifetimes in space; model verification and development; and correlation factors between space-exposure and ground-facilities enabling more accurate in-space performance predictions based on ground-laboratory testing. A few of the many experiment results and observations, and their impacts, are provided. Those highlighted include examples on improved understanding of atomic oxygen scattering mechanisms, LEO coating durability results, and polymer erosion yields and their impacts on spacecraft design. The MISSE 2 Atomic Oxygen Scattering Chamber Experiment discovered that the peak flux of scattered AO was determined to be 45 deg from normal incidence, not the model predicted cosine dependence. In addition, the erosion yield (E(sub y)) of Kapton H for AO scattered off oxidized-Al is 22% of the E(sub y) of direct AO impingement. These results were used to help determine the degradation mechanism of a cesium iodide detector within the Hubble Space Telescope Cosmic Origins Spectrograph Experiment. The MISSE 6 Indium Tin Oxide (ITO) Degradation Experiment measured surface electrical resistance of ram and wake ITO coated samples. The data confirmed that ITO is a stable AO protective coating, and the results validated the durability of ITO conductive coatings for solar arrays for the Atmosphere-Space Transition 2 Explorer program. The MISSE 2, 6 and 7 Polymer Experiments have provided LEO AO Ey data on over 120 polymer and composites samples. The flight E(sub y) values were found to range from 3.05 x 10(exp -26) cu cm/atom for the AO resistant polymer CORIN to 9.14 x 10(exp -26) cu cm/atom for polyoxymethylene (POM). In addition, flying the same polymers on different missions has advanced the understanding of the AO E(sub y) dependency on solar exposure for polymers containing fluorine. The MISSE polymer results are highly requested and have impacted spacecraft design for WorldView-2 & -3, the Global Precipitation Measurement-Microwave Imager, and other spacecraft. The flight data has enabled the development of an Atomic Oxygen Erosion Predictive Tool that allows the erosion prediction of new and non-flown polymers. The data has also been used to develop a new NASA Technical Standards Handbook "Spacecraft Polymers Atomic Oxygen Durability Handbook." Many intangible benefits have also been derived from MISSE. For example, over 40 students have collaborated on Glenn's MISSE experiments, which have resulted in greater than $80K in student scholarships and awards in national and international science fairs. Students have also given presentations and won poster competition awards at international space conferences.

Flight Experiment↗
DOE OSTI2021

Aqueous-soluble bipyridine cobalt($\tiny{II}$/$\tiny{III}$) complexes act as direct redox mediators in photosystem I-based biophotovoltaic devices

Sustainable energy production is critical for meeting growing worldwide energy demands. Due to its stability and reduction potential, photosystem I (PSI) is attractive as the photosensitizer in biophotovoltaic devices. Herein, we characterize aqueous and organic solvent soluble synthetic bipyridine-based cobalt complexes as redox mediators for PSI-based biophotovoltaics applications. Cobalt-based complexes are not destructive to protein and have appropriate midpoint potentials for electron donation to PSI. We report on PSI stability in organic solvents commonly used in biophotovoltaics. We also show the effects of a mixed organic solvent phase on PSI reduction kinetics, slowing reduction rates approximately 8–38 fold as compared to fully aqueous systems, with implications for dye regeneration rates in PSI-based biophotovoltaics. Further, we show evidence of direct electron transfer from cobalt complexes to PSI. Finally, we report on photocurrent generation from Co mediator-PSI biophotovoltaic devices. Taken together, we discuss the development of novel Co complexes and our ability to fine-tune their characteristics via functional groups and counteranion choice to drive interaction with a biological electron acceptor on multiple levels from redox midpoints, spectral overlap, and solvent requirements, among others. This work suggests that fine-tuning of redox active species for interaction with a biological partner is possible for the creation and improvement of low cost, carbon-neutral energy production in the future.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Balancing moisture and oxygen can match the crystallization dynamics of inert halide perovskite processing

Understanding crystallization in ambient environments is essential for scaling the fabrication of halide perovskite solar cells. Antisolvent-free perovskite deposition offers improved compatibility with high-throughput processing but introduces distinct crystallization dynamics relative to the more ubiquitous use of antisolvents in lab-scale perovskite fabrication. These dynamics are driven by interactions between solutes, solvent and the deposition environment. Using in situ wide-angle X-ray scattering during spin-coating and annealing, we demonstrate how relative humidity (RH) and oxygen, can be tuned to drive polytype evolution during ambient crystallization of formamidinium lead iodide to match that of inert synthesis and achieve comparable film and device quality. In an inert (N 2 ) environment, we find that perovskite films follow a well-established 2H → 3C phase transformation with a short period of coexistence of the 4H and 6H phase during heating. During crystallization in dry air (RH 0%), the added presence of oxygen leads to the dominance of 4H intermediate for an extended duration, establishing a 2H → 4H → 3C pathway. Introducing low humidity (RH 10%) suppresses the 4H phase to a short-lived intermediate above 100 °C, facilitating a more direct transition to the desired 3C phase and almost replicating the crystallization behavior observed under inert conditions. Interestingly, films crystallized under RH 10% show a lower onset temperature for the perovskite 3C phase than under N 2 . At higher humidity (RH 40%), the strong interaction of oxygen and moisture with iodoplumbates appears to stabilize higher order polytypes (4H and 6H). Devices fabricated under RH 10% achieve higher efficiency and enhanced stability compared to those produced under inert atmosphere. These findings provide mechanistic insight into crystallization pathways in different environments and provide a framework to transfer processes from inert to ambient conditions. The results highlight the critical role of controlled humidity in tuning antisolvent-free perovskite crystallization for scalable processing.

Hossain, Maimur [Univ. of California, San Diego, C↗
DOE OSTI2024

Carboxylating Elastomer via Thiol‐Ene Click Reaction to Improve Miscibility with Conjugated Polymers for Mechanically Robust Organic Solar Cells with Efficiency of 19%

Abstract Incorporating flexible insulating polymers is a straightforward strategy to enhance the mechanical properties of rigid conjugated polymers, enabling their use in flexible electronic devices. However, maintaining electronic characteristics simultaneously is challenging due to the poor miscibility between insulating polymers and conjugated polymers. This study introduces the carboxylation of insulating polymers as an effective strategy to enhance miscibility with conjugated polymers via surface energy modulation and hydrogen bonding. The carboxylated elastomer, synthesized via a thiol‐ene click reaction, closely matches the surface energy of the conjugated polymer. This significantly improves the mechanical properties, achieving a high crack‐onset strain of 21.48%, surpassing that (5.93%) of the unmodified elastomer:conjugated polymer blend. Upon incorporating the carboxylated elastomer into PM6:L8‐BO‐based organic solar cells, an impressive power conversion efficiency of 19.04% is attained, which top‐performs among insulating polymer‐incorporated devices and outperforms devices with unmodified elastomer or neat PM6:L8‐BO. The superior efficiency is attributed to the optimized microstructures and enhanced crystallinity for efficient and balanced charge transport, and suppressed charge recombination. Furthermore, flexible devices with 5% carboxylated elastomer exhibit superior mechanical stability, retaining ≈88.9% of the initial efficiency after 40 000 bending cycles at a 1 mm radius, surpassing ≈83.5% for devices with 5% unmodified elastomer.

Chemistry↗
DOE OSTI2017

Si Doped Hafnium Oxide-A “Fragile” Ferroelectric System

Here, silicon doped hafnium oxide was the material used in the original report of ferroelectricity in hafnia in 2011. Since then, it has been subject of many further publications including the demonstration of the world's first ferroelectric field-effect transistor in the state-of-the-art 28 nm technology. Though many studies are conducted with a strong focus on application in memory devices, a comprehensive study on structural stability in these films remains to be seen. In this work, a film thickness of about 36 nm, instead of the 10 nm used in most previous studies, is utilized to carefully probe how the concentration range impacts the evolution of phases, the dopant distribution, the field cycling effects, and their interplay in the macroscopic ferroelectric response of the films. Si:HfO2 appears to be a rather fragile system: different phases seem close in energy and the system is thus rich in competing phenomena. Nonetheless, it offers ferroelectricity or field-induced ferroelectricity for elevated annealing conditions up to 1000 °C. Similar to the measures taken for conventional ferroelectrics such as lead zirconate titanate, engineering efforts to guarantee stable interfaces and stoichiometry are mandatory to achieve stable performance in applications such as ferroelectric memories, supercapacitors, or energy harvesting devices.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Hybrid Down-Converting Structures for Solid State Lighting

Achieving higher luminous efficacy in phosphor converted light emitting diodes (pcLED) requires breakthroughs in down-converting materials that provide high conversion efficiency, tunable narrow bandwidth emission, and temperature/chemical stability. While conventional bulk phosphors are currently the dominant down-converters used in high power solid-state lighting (SSL) applications, their performance is limited by intrinsic properties such as high scattering cross-sections and large emission bandwidth. On the other hand, conventional luminescent nanocrystals (e.g, quantum dots or QDs) have high self-absorption and poor thermal and chemical stability for HB LEDs. Ultimately, these materials will enable a new generation of solid state lighting devices with high luminous efficacies, high color and thermal stability, and with spectral efficiency near the theoretical maximum luminous efficacy of radiation (LER), as a result of their color tunability and narrow bandwidths (FWHM < 30nm).

36 MATERIALS SCIENCE↗
DOE OSTI2023

Impact of dipolar molecules on the reliability of organic photovoltaic cells

Blending two non-fullerene acceptors (NFAs) to form bulk heterojunctions (BHJs) in ternary organic photovoltaics (OPVs) has been shown to lead to an end-capping exchange reaction that results in the generation of several new dipolar species whose impact on OPV operational stability remains uncertain. Here, we investigate the reliability of a ternary OPV system intentionally blended with dipolar NFA molecules. We reveal that an intrinsic contribution to OPV degradation is the reorganization and reorientation of the dipolar molecules during operation, which leads to an increased dielectric constant (ε r ) of the BHJ. Consequently, the electric field across the BHJ with dipolar molecules decreases compared with that of a non-dipolar BHJ under the same applied voltage, leading to a larger reduction in charge collection efficiency over time. This result has implications on the stability of a range of organic electronic devices containing dipolar molecules.

14 SOLAR ENERGY↗
NASA NTRS1973

Review of drag measurements from flight tests of manned aircraft with comparisons to wind-tunnel predictions

In-flight studies of the overall and local components of drag of many types of aircraft were conducted. The primary goal of these studies was to evaluate wind-tunnel and semiempirical prediction methods. Some evaluations are presented in this paper which may be summarized by the following observations: Wind-tunnel predictions of overall vehicle drag can be accurately extrapolated to flight Reynolds numbers, provided that the base drag is removed and the boattail areas on the vehicle are small. The addition of ablated roughness to lifting body configurations causes larger losses in performance and stability than would be expected from the added friction drag due to the roughness. Successful measurements of skin friction have been made in flight to Mach numbers above 4. A reliable inflatable deceleration device was demonstrated in flight which effectively stabilizes and decelerates a lifting aircraft at supersonic speeds.

Pyle, J. S.↗
NASA NTRSDate not supplied

Development and Testing of Pulse Guns for Combustion Instability Testing

Combustion stability requirements of a liquid propellant rocket engine are most commonly verified by evaluating the oscillatory pressure or vibration characteristics following an artificial disturbance of the combustion in the combustion chamber. Two types of devices are most commonly used for dynamic stability rating – nondirectional bombs and pulse guns. Bombs have historically been used most often, especially for the large engines developed around the Apollo era. However, bombs in recent years have become much more expensive and difficult to procure, and their transportation and handling requirements have become more demanding. Pulse guns, with inherently less expensive materials, and far less restrictive handling and shipping requirements, have become an attractive alternative. The NASA Marshall Space Flight Center has developed a pulse gun for use during future development programs at the center, and as a design reference for interested commercial users. The objective of this paper is to present the different variants of the pulse gun and characterize performance over a range of parameters. The parameters include the breech diameter and corresponding volume, barrel length, amount of gun powder used, the method of containing the gunpowder within the breech, and the pressure rating of the burst disk. In total, 44 tests were conducted with the pulse gun firing into a test chamber pressurized to 2300 psig with gaseous nitrogen. The best experimental results – including the highest and most consistent peak pressure amplitudes recorded by dynamic pressure sensors in the test chamber – were from a configuration consisting of a 0.40” inner-diameter breech, 15-16 grains of gunpowder wrapped in cigarette paper, and a 24,000 psid burst disk. With this configuration, the zero-to-peak overpressures recorded in the test chamber ranged from about 37% to 58% of the 2300 psig mean pressure, which is adequate for typical combustion stability rating. To complement the data analysis, the acoustics of the pressure waves as they propagated through the pulse gun and into the test chamber were modeled. A more comprehensive final report of this pulse gun development program is planned to be available in the near future.

Pulse Gun↗
DOE OSTI2023

Effects of Residual DMSO Adduct on Photonically Cured MAPbI 3 Solar Cells

Defects and impurities in halide perovskite solar cells can negatively impact device performance and long-term stability. In this study, we identify photonically cured methylammonium (MA) lead iodide films contain a residual adduct, MA 2 Pb 3 I 8 (dimethyl sulfoxide) 2 (MA 2 Pb 3 I 8 (DMSO) 2 ), that reduces photocurrent generation in perovskite solar cells (PSCs). This is evidenced by a decrease in the external quantum efficiency (EQE) near 400 nm. Similar EQE reductions were observed in PSCs produced using high-speed processes but have not been thoroughly examined. Through X-ray diffraction patterns and Fourier transform infrared spectroscopy, we establish the photo-inactive MA 2 Pb 3 I 8 (DMSO) 2 as the culprit for the EQE reduction. Combined experimental and simulation results reveal that the MA 2 Pb 3 I 8 (DMSO) 2 phase is located at the hole transport layer/ interface, not on the surface, resulting in lower quantum efficiency and surface photovoltage in the short wavelength region. The residual adduct is kinetically trapped due to the short processing time (20 ms) and crystallization direction but can be removed by an additional photonic pulse. Furthermore, this study highlights the need for careful examination of resulting materials beyond device efficiency when transitioning from laboratory processing to industrial high-speed methods.

14 SOLAR ENERGY↗
DOE OSTI2013

Substituent effects in a series of 1,7-C[subscript 60](R[subscript F])[subscript 2] compounds (R[subscript F] = CF[subscript 3], C[subscript 2]F[subscript 5], n-C[subscrip 3]F[subscript 7], i-C[subscript 3]F[subscript 7], n-C[subscript 4]F[subscript 9], s-C[subscript 4]F[subscript 9], n-C[subscript 8]F[subscript 17]): electron affinities, reduction potentials and E(LUMO) values are not always correlated

A series of seven structurally-similar compounds with different pairs of R{sub F} groups were prepared, characterized spectroscopically, and studied by electrochemical methods (cyclic and square-wave voltammetry), low-temperature anion photoelectron spectroscopy, and DFT calculations (five of the compounds are reported here for the first time). This is the first time that a set of seven R{sub F} groups have been compared with respect to their relative effects on E{sub 1/2}(0/-), electron affinity (EA), and the DFT-calculated LUMO energy. The compounds, 1,7-C{sub 60}(R{sub F}){sub 2} (R{sub F} = CF{sub 3}, C{sub 2}F{sub 5}, i-C{sub 3}F{sub 7}, n-C{sub 3}F{sub 7}, s-C{sub 4}F{sub 9}, n-C{sub 4}F{sub 9} and n-C{sub 8}F{sub 21}), were found to have statistically different electron affinities (EA), at the {+-}10 meV level of uncertainty, but virtually identical first reduction potentials, at the {+-}10 mV level of uncertainty. The lack of a correlation between EA and E{sub 1/2}(0/-), and between E(LUMO) and E{sub 1/2}(0/-), for such similar compounds is unprecedented and suggests that explanations for differences in figures of merit for materials and/or devices that are based on equating easily measurable E{sub 1/2}(0/-) values with EAs or E(LUMO) values should be viewed with caution. The solubilities of the seven compounds in toluene varied by nearly a factor of six, but in an unpredictable way, with the C{sub 2}F{sub 5} and s-C{sub 4}F{sub 9} compounds being the most soluble and the i-C{sub 3}F{sub 7} compound being the least soluble. The effects of the different R{sub F} groups on EAs, E(LUMO) values, and solubilities should help fluorine chemists choose the right R{sub F} group to design new materials with improved morphological, electronic, optical, and/or magnetic properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Switching charge states in quasi-2D molecular conductors

Abstract 2D molecular entities build next-generation electronic devices, where abundant elements of organic molecules are attractive due to the modern synthetic and stimuli control through chemical, conformational, and electronic modifications in electronics. Despite its promising potential, the insufficient control over charge states and electronic stabilities must be overcome in molecular electronic devices. Here, we show the reversible switching of modulated charge states in an exfoliatable 2D-layered molecular conductor based on bis(ethylenedithio)tetrathiafulvalene molecular dimers. The multiple stimuli application of cooling rate, current, voltage, and laser irradiation in a concurrent manner facilitates the controllable manipulation of charge crystal, glass, liquid, and metal phases. The four orders of magnitude switching of electric resistance are triggered by stimuli-responsive charge distribution among molecular dimers. The tunable charge transport in 2D molecular conductors reveals the kinetic process of charge configurations under stimuli, promising to add electric functions in molecular circuitry.

Huang, Yulong (ORCID:0000000296160134)↗
NASA NTRS1981

Simple JFET oscillator

Device used in mixers, modulators, and function generators provides stable sine-wave signal compatible with both integrated circuits and discrete-component assemblies. Oscillator's frequency is tunable over narrow band about design value. Frequency range, stability, linearity, and low power drain of device are suited to communications receivers and transmitters and digital microprocessors, computers, and displays. Circuit simplicity allows for easy monolithic construction.

Kleinberg, L. L.↗
DOE OSTI2017

Wireless Chemical Sensor Systems (Optimization of Field-Structured Chemiresistors for in situ Quantification of Propellant Stabilizer Concentration)

This project is a Cooperative Research and Development Agreement (CRADA) with International Electronic Machines Corp. (IEM, Troy, NY), who is contracted through the U.S. Naval Air Systems Command (NAVAIR) (under SBIR N111-010) to develop an in situ wireless chemical sensor system called the Stabilizer Level Accurate Measurement System (SLAMS). The SLAMS device is specified to include a miniature, very thin, self-contained chemical-sensor node to detect and track the level of stabilizer present in various PADs and CADs. IEM is focused on the wireless sensor platform, node communication, and electronics; whereas Sandia National Laboratories’ (SNL’s) efforts are focused on the chemical sensor development and integration. The sensor technology being employed is known as field-structured chemiresistors (FSCRs), which was invented by James Martin, et al. (SNL) and refined by Martin and Read. These sensors are small, require very little power, and have tunable sensitivity and selectivity. In the following, we discuss SNL’s efforts to optimize the FSCRs for the demanding chemical and environmental conditions that will be encountered in this application.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Oxygen demand for the stabilization of the organic fraction of municipal solid waste in passively aerated bioreactors

Highlights: • The use of an passively aerated reactor enables effective stabilization of OFMSW. • Convective air flow does not inhibit the aerobic stabilization of waste. • The use of an passively aerated reactor reduces the heat loss due to convection. • The volume of supplied air exceeds 1.7–2.88 times the microorganisms demand. - Abstract: Conventional aerobic waste treatment technologies require the use of aeration devices that actively transport air through the stabilized waste mass, which greatly increases operating costs. In addition, improperly operated active aeration systems, may have the adverse effect of cooling the stabilized biomass. Because active aeration can be a limiting factor for the stabilization process, passive aeration can be equally effective and less expensive. Unfortunately, there are few reports documenting the use of passive aeration systems in municipal waste stabilization. There have been doubts raised as to whether a passive aeration system provides enough oxygen to the organic matter mineralization processes. In this paper, the effectiveness of aeration during aerobic stabilization of four different organic fractions of municipal waste in a reactor with an integrated passive ventilation system and leachate recirculation was analyzed. For the study, four fractions separated by a rotary screen were chosen. Despite the high temperatures in the reactor, the air flow rate was below 0.016 m{sup 3}/h. Using Darcy’s equation, theoretical values of the air flow rate were estimated, depending on the intensity of microbial metabolism and the amount of oxygen required for the oxidation of organic compounds. Calculations showed that the volume of supplied air exceeded the microorganisms demand for oxidation and endogenous activity by 1.7–2.88-fold.

54 ENVIRONMENTAL SCIENCES↗