Dual-flow System Research Articles

Comparative Analysis of Ventilation Systems for Aging Salami

The aim of this study was to evaluate the influence of different ventilation systems in two aging cells. One cell featured transverse airflow starting from the top, while the other had a dual-flow system with vertical air motion from top to bottom and vice versa. In addition to monitoring weight loss during aging, chemical and physical analyses were conducted on various salamis to assess the influence of ventilation both between the two aging cells and among different positions of the salamis within the same cell. It was found that the dual-evaporator (DEV) cell behaved better than transverse flow (TFL) cell.

An innovative gas inlet design in a microwave plasma chemical vapor deposition chamber for high-quality, high-speed, and high-efficiency diamond growth

A novel design of the gas inlet system in a diamond microwave plasma chemical vapor deposition growth chamber has been reported in this paper. The design is targeting for high-quality, high-speed, and high-efficiency diamond material fabrication. By introducing a gas inlet hole into the susceptor, we expand the ways of gas introduction for diamond growth. After extensive numerical and experimental investigation, we have found that the introduction of methane and doping gas inlet from the hole of below while the hydrogen from the top is feasible for realizing the target. The growth and doping species could be confined around the substrate, making efficient usage of the precursors. The plasma state change caused by the difference of the gas inlet modes has been ascribed to the resulted gas distribution in the chamber. The measured growth rate has been increased to 32 μm h−1, which is 16 times higher than traditional gas inlet configuration. Meanwhile, a large improvement of the nitrogen doping concentration has been achieved. Besides, with the increase of growth rate and nitrogen incorporation efficiency, the crystal quality and surface morphology keep in an acceptable degree. In this mode, the dual gas flow system can perfectly solve the contradiction among the crystal quality, growth rate, and doping efficiency, commonly existing during the material fabrication process, the chamber contamination could be significantly suppressed due to the constrained distribution of methyl and doping species, making the fabrication cost much lower. The results of repetitive experiments indicate that other residual impurities present in the chamber of microwave plasma chemical vapor deposition could likely regulate the threshold concentration of nitrogen required for accelerating the growth rate during the nitrogen doped diamond growth, which have a significant effect on the diamond growth.

A rat model of dual-flow liver machine perfusion system.

As clinical liver perfusion systems use portal vein and artery flow, dual perfusion techniques are required even in small animal models in order to reproduce clinical setting. The aim of this study was to construct a new dual-flow perfusion system in rat model and optimized the oxygen supply to ensure the aerobic metabolization. The dual-flow circuit was fabricated using rat liver and whole blood samples as perfusates. The oxygen supply was controlled according to the amount of dissolved oxygen in the perfusate. Perfusate parameters and adenosine triphosphate (ATP) levels were analyzed to evaluate organ function and metabolic energy state. Stored whole blood also tested the suitability as perfusate. Stored blood showed decrease oxygen delivery and liver function compared to fresh blood. Using fresh blood as perfusate with air only, the dissolved oxygen levels remained low and anaerobic metabolism increased. In contrast, with oxygen control at living body level, anaerobic metabolism was well suppressed, and tissue ATP content was increased. We developed a new dual-flow system that enable to reproduce the clinical settings. The perfusion system showed the possibility to improve the energy metabolic state of the perfused organ under appropriate partial pressure of oxygen.

Combined hydrogen production and electricity storage using a vanadium-manganese redox dual-flow battery

A redox dual-flow battery is distinct from a traditional redox flow battery (RFB) in that the former includes a secondary energy platform, in which the pre-charged electrolytes can be discharged in external catalytic reactors through decoupled redox-mediated hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The concept offers several advantages over conventional electrolysis in terms of safety, durability, modularity, and purity. In this work, we demonstrate a vanadium-manganese redox-flow battery, in which Mn 3+ /Mn 2+ and V 3+ /V 2+ respectively mediate the OER and the HER in Mo 2 C-based and RuO 2 -based catalysts. The flow battery demonstrates an average energy efficiency of 68% at a current density of 50 mA ⋅ cm −2 (cell voltage = 1.92 V) and a relative energy density 45% higher than the conventional all-vanadium RFB. Both electrolytes are spontaneously discharged through redox-mediated HER and OER with a faradic efficiency close to 100%. Vanadium-manganese dual-flow system for electricity storage and hydrogen production Hydrogen production via the catalytic discharge of vanadium(II) electrolyte on Mo 2 C Oxygen production via the catalytic discharge of manganese(III) electrolyte on RuO 2 Battery energy efficiency of 68% and water splitting voltage efficiency of 64.1% The redox dual-flow battery system offers the opportunity to combine electricity storage and renewable hydrogen production. Reynard and Girault present a vanadium-manganese redox dual-flow system that is flexible, efficient, and safe and that provides a competitive alternative for large-scale energy storage, especially for service stations for both fast charging of electric vehicles and hydrogen refueling of fuel cell vehicles.

Breakthrough curves of dye tracing tests in karst aquifers: Review of effective parameters based on synthetic modeling and field data

Breakthrough curves (BTCs) are known as adequate evidence to characterize karst aquifers which mainly specified by dual flow systems (matrix and conduit) as well as some degree of connection between dual media. Conduit Flow Process version 2 (CFPv2) is a discrete conduit continuum model applying which it is possible to simulate such characteristics. In this research, first CFPv2 was employed to evaluate the effect of several factors including hydraulic conductivity, exchange flow, tracing distance, hydraulic gradient, and conduit diameter and roughness on BTCs in a synthetic karst aquifer. Then, 253 BTCs from 24 dye tracing tests, conducted in karstic aquifers of Iran, were analyzed to evaluate the effect of hydraulic gradient and tracing distance on the BTCs with taking into account the effect of medium type (matrix or conduit) and karst development. These tests were conducted under either natural or elevated man-made hydraulic gradient conditions. The results revealed that peak concentration decreased with enlarging conduit diameter because of considerable flow rate. Likewise, it decreases over longer distances specifically in the elevated man-made hydraulic conditions. However, with increasing hydraulic gradient, peak concentration and its timing have upward and downward trends, respectively. When BTCs start to demonstrate tailing and become flattened, it could be an indication of low matrix hydraulic conductivity or lower hydraulic gradient in conduit as a result of less exchange flow from the matrix into conduits. Based on this study a new intermixture of flow and solute transport parameters was engineered to classify karst development. High peak concentration, short peak time, high velocity particularly over long distances and under the natural hydraulic gradient conditions and feasible conduit flow regime whether laminar or turbulent suggested as indication of well-developed karstic system.

Quantifying groundwater flow variability in a poorly cemented fractured sandstone aquifer to inform in situ remediation

This study applies innovative methods to characterize and quantify the magnitude of groundwater flow in a fractured and variably cemented sandstone aquifer to inform an in-situ remediation strategy for trichloroethene (TCE) contamination. A modified active-distributed temperature sensing (A-DTS) approach in which fiber optic cables were permanently grouted in the borehole was used to quantify groundwater flow rates. Two additional tracer tests were conducted: 1) fluorescein tracer injection followed by rock coring and sampling for visual mapping and porewater analysis, and 2) deployment of passive flux meters in conventional monitoring wells to evaluate groundwater velocity and mass flux distributions. Forced gradient injection of fluorescein tracer suggests a dual porosity flow system wherein higher rates of groundwater flow occur within discrete features including highly permeable bedding planes and fractures, with slower flow occurring within the rock matrix. Tracer was observed and detected in the unfractured matrix porewater >1.5 m away from the injection well. Beyond this distance, >6 m radially away from the injection hole, tracer was primarily detected within and adjacent to high transmissivity fractures serving as preferential flow paths. The Darcy flux calculated using active distributed temperature sensing (A-DTS) shows depth-discrete values ranging from 7 to 60 cm/day, with average and median values of 23 and 17 cm/day, respectively. Passive Flux Meters (PFMs) deployed in three conventional monitoring wells with slotted screens and sand filter packs showed groundwater flux values ranging from 2 to 11 cm/day, with an overall average of 4 cm/day and are likely biased low due to spreading in the sand pack. The study results were used to inform an in-situ remediation system design including the proposed injection well spacing and the amendment delivery approach. In addition, the results were used to build confidence in the viability of delivering an oxidant to the rock matrix via advective processes. This is important because 1) the matrix is where the majority of the TCE mass occurs, and 2) it provides insights on processes that directly affect remedial performance expectations given advective delivery to preferential pathways and the matrix overcomes diffusion only conditions.

Speed regulation control of tractors’ new dual-flow transmission system based on slip rate resistance classification

Fluctuations in operation resistance during the operating process lead to reduced efficiency in tractor production. To address this problem, the project team independently developed and designed a new type of hydraulic mechanical continuously variable transmission (HMCVT). Based on introducing the mechanical structure and transmission principle of the HMCVT system, the priority of slip rate control and vehicle speed control is determined by classifying the slip rate. In the process of vehicle speed control, the driving mode of HMCVT system suitable for the current resistance state is determined by classifying the operation resistance. The speed change rule under HMT and HST modes is formulated with the goal of the highest production efficiency, and the displacement ratio adjustment surfaces under HMT and HST modes are determined. A sliding mode control algorithm based on feedforward compensation is proposed to address the problem that the oil pressure fluctuation has influences on the adjustment accuracy of hydraulic pump displacement. The simulation results of Simulink show that this algorithm can not only accurately follow the expected signal changes, but has better tracking stability than traditional PID control algorithm. The HMCVT system and speed control strategy models were built, and simulation results show that the speed control strategy can restrict the slip rate of driving wheels within the allowable range when load or road conditions change. When the tractor speed is lower than the lower limit of the high-efficiency speed range, the speed change law formulated in this paper can improve the tractor speed faster than the traditional rule, and effectively ensure the production efficiency. The research results are of great significance for improving tractor’s adaptability to complex and changeable working environment and promoting agricultural production efficiency.

Low power plasma spray assisted thermal barrier coating repair without the plugging of cooling holes

Abstract Currently operating new generation aircraft engines are equipped with multi-hole combustion chambers, coated with a thick ZrO2-4 mol% Y2O3 (YpSZ) thermal barrier coating (TBC). The local repair of such multi-hole combustors requires the development of specific deposition methods. This paper describes a modified version of a low power plasma reactor (LPPR), upgraded with two opposite gas flows to prevent cooling channel plugging. The influence of some experimental parameters (plasma power density, spray distance and precursor concentration) on the repaired TBC microstructure is examined. A short spray distance, associated with a low power density and a low concentration of nitrate precursors, led to a suitable microstructure of the deposited YpSZ. Moreover, FTIR spectroscopy and SEM-EDS analysis revealed the efficient conversion of the nitrate precursors into oxide and the good infiltration of the deposited YpSZ into the damaged area. Finally, it is shown that, once the deposition parameters have been optimized, a dual flow system effectively allows local repair to be carried out without plugging the cooling system.

Full-loop study of a dual fluidized bed cold flow system: Hydrodynamic simulation and validation

The unsteady behaviors of the air-silica sand flow in a lab-scale dual fluidized bed gasification cold flow system have been studied. A two-dimensional computational fluid dynamics full-loop model with poly-size distribution in solid phases was developed as an innovation of this study to investigate the effects of crucial parameters on system hydrodynamics. The results showed a decrease in the mixture static pressure from the bottom to the upper regions of the system, which maintained the system operations stable. The riser air inlet velocity and the gasifier static bed height were found to play considerable roles in enhancing the total sand flow rates. The same tendencies in the prediction and experiment of both the mixture pressure and the sand flow rate showed the feasibility of the proposed model. Besides, the residual evaluation enhanced data reliability and supported model validation. Especially, undesirable phenomena possibly occurring in the system operation under improper conditions could also be predicted. Accordingly, the inventory of bed material and the fluidizing gas flow rates should be suitably regulated to maintain pressure balances, trouble-free continuous flow, optimal sand circulation rate, and low solids loss. Furthermore, the obtained results in this study can be used as a reference for optimizing the designs and operational conditions of large-scale plants.

Energy efficient methods of protecting buildings from cold air flows

In this work, we study new innovative methods for creating an additive temperature environment, study the influence of a new type of infrared devices such as air and air-thermal curtains on the living conditions and infiltration parameters of buildings and structures from penetrating cold air flows. For calculating these structures, the engineering and technical methods of V.M. Elterman was used, based on the methods of calculating heated air curtains of Soviet scientists V.V. Baturin, I.A. Shepelev, S.E. Butakov. Additionally, the method of calculating air curtains by M.E. Diskin was used. We studied the distribution of temperature fields in the gate area of the building, in which road transport is being repaired. The experiments showed that the best indoor microclimate is achieved by using dual-flow systems consisting of a heated air curtain and an air curtain. The study of thermoelectric systems showed that it is possible to recuperate about 500 watts of electrical energy in this case. Studies have shown that there are modern, innovative developments, use of which improves the microclimate in the rooms without spending additional energy resources.

Clinical and surgical consequences of the COVID-19 pandemic for patients with pediatric urological problems: Statement of the EAU guidelines panel for paediatric urology, March 30 2020

SummaryThe COVID-19-pandemic forces hospitals to reorganize into a dual patient flow system. Healthcare professionals are forced to make decisions in patient prioritization throughout specialties. Most pediatric urology pathologies do not require immediate or urgent care, however, delay may compromise future renal function or fertility. Contact with patients and parents, either physical in safe conditions or by (video)telephone must continue.The Paediatric-Urology-Guidelines-panel of the EAU proposes recommendations on prioritization of care. Pediatric-Urology program directors must ensure education, safety and attention for mental health of staff. Upon resumption of care, adequate prioritization must ensure minimal impact on outcome.

Simplified physically based models for free-surface flow in karst systems

Most karst aquifers are characterized as a dual-flow system comprised of a highly conductive conduit network embedded in a low porosity matrix. The conduits are hydraulically connected to the matrix and behave either as a drain or a source depending on the recharge conditions. Simplified physically based models are herein employed to simulate the spring outflow for such aquifer systems. The processes consist of a free-surface flow in the conduit that is interacting laterally with a laminar groundwater flow in the surrounding matrix. The conduit is subject to a concentrated recharge at its upstream end while the groundwater aquifer is subject to a diffuse recharge over its contributing surface area. The flow system is described by a coupled system of partial differential equations: the conduit flow is approximated by the kinematic wave equation and the groundwater flow by the linearized Boussinesq equation. The governing equations are solved using the Laplace transform method after an appropriate linearization of the nonlinear coefficient. The derived spring discharge models are a function of three dimensionless parameters: the time lag parameter ξ, the lumped conduit parameter λ, and the aquifer parameter η. The simulation results highlight the contrast between pressure-driven and gravity-driven flows and the importance of the conduit-matrix interaction on the response of the karst system. Application of the models on real karst aquifers demonstrates their effectiveness in simulating the observed spring hydrograph using lumped physical parameters of the karst system.

Catchment‐scale conceptual modelling of water and solute transport in the dual flow system of the karst critical zone

AbstractHydrological and hydrochemical processes in the critical zone of karst environments are controlled by the fracture‐conduit network. Modelling hydrological and hydrochemical dynamics in such heterogeneous hydrogeological settings remains a research challenge. In this study, water and solute transport in the dual flow system of the karst critical zone were investigated in a 73.5‐km2 catchment in southwest China. We developed a dual reservoir conceptual run‐off model combined with an autoregressive and moving average model with algorithms to assess dissolution rates in the “fast flow” and “slow flow” systems. This model was applied to 3 catchments with typical karst critical zone architectures, to show how flow exchange between fracture and conduit networks changes in relation to catchment storage dynamics. The flux of bidirectional water and solute exchange between the fissure and conduit system increases from the headwaters to the outfall due to the large area of the developed conduits and low hydraulic gradient in the lower catchment. Rainfall amounts have a significant influence on partitioning the relative proportions of flow and solutes derived from different sources reaching the underground outlet. The effect of rainfall on catchment function is modulated by the structure of the karst critical zone (e.g., epikarst and sinkholes). Thin epikarst and well‐developed sinkholes in the headwaters divert more surface water (younger water) into the underground channel network, leading to a higher fraction of rainfall recharge into the fast flow system and total outflow. Also, the contribution of carbonate weathering to mass export is also higher in the headwaters due to the infiltration of younger water with low solute concentrations through sinkholes.

A New Equation Solver for Modeling Turbulent Flow in Coupled Matrix-Conduit Flow Models.

Karst aquifers represent dual flow systems consisting of a highly conductive conduit system embedded in a less permeable rock matrix. Hybrid models iteratively coupling both flow systems generally consume much time, especially because of the nonlinearity of turbulent conduit flow. To reduce calculation times compared to those of existing approaches, a new iterative equation solver for the conduit system is developed based on an approximated Newton-Raphson expression and a Gauß-Seidel or successive over-relaxation scheme with a single iteration step at the innermost level. It is implemented and tested in the research code CAVE but should be easily adaptable to similar models such as the Conduit Flow Process for MODFLOW-2005. It substantially reduces the computational effort as demonstrated by steady-state benchmark scenarios as well as by transient karst genesis simulations. Water balance errors are found to be acceptable in most of the test cases. However, the performance and accuracy may deteriorate under unfavorable conditions such as sudden, strong changes of the flow field at some stages of the karst genesis simulations.

Dual-flow in karst aquifers toward a steady discharge spring (Presciano, Central Italy): influences on a subsurface groundwater dependent ecosystem and on changes related to post-earthquake hydrodynamics

The Presciano spring system (Central Italy) is fed by a fractured carbonate regional aquifer and shows peculiar hydrogeological, physicochemical, hydrogeochemical and biological features that led to hypothesis about local superimposition of a dual groundwater flow system. The components of this system are fast-flow and baseflow groundwater paths. Hydrogeochemical and isotopic (δ18O and δD for H2O, and δ34\( {\text{S}}_{{{\text{SO}}_{ 4} }} \) and δ18\( {\text{O}}_{{{\text{SO}}_{ 4} }} \)) data were used to test this conceptual model. Differences in physico-chemistry and ion concentrations were recorded for two main spring sectors, attributable to different groundwater flowpaths. Environmental isotope analyses allowed distinguishing different recharge areas for the two groups: more depleted values (−10.4 ‰ δ18O and −71 ‰ δD) indicated the existence of a flowpath influenced by a higher elevation recharge area, whereas enriched isotope signals (−9.9 ‰ δ18O and −66 ‰ δD) supported a regional recharge area of local water infiltration. The existence of a dual flow system is also reflected in the relationship between SO42− concentration and SO42− isotope data. The isotopic pattern of SO42− reflects the seasonal contributions by the two flow paths to the springs: after snowmelt, the isotopic sulphate value in the spring outlet is very similar to the spring sector fed by the fast flow component, while, after the spring exhaustion period, its isotopic composition is very similar to the base flow spring sectors fed by the fracture network. The influence of the different flowpaths has also been highlighted by changes in water isotope composition after the 2009 L’Aquila earthquake in this area: the strong homogeneous response of the spring system can be attributed to a cleaning of the fracture system, which affected the aquifer at regional scale. Additional investigations adopting the geoelectrical tomography technique highlighted the possibility of the existence of a buried karst channel or at least high-permeability shear zone at the contact between the carbonate aquifer and the fluvio-lacustrine quaternary deposits, where the spring system is located. Biological indicators, such as groundwater copepods also showed a response to the dual flowpath regime. The results of this study have great relevance for a better management of the Presciano spring habitat, which is increasingly threatened by anthropogenic disturbance.

Comparison of a karst groundwater model with and without discrete conduit flow

Karst aquifers exhibit a dual flow system characterized by interacting conduit and matrix domains. This study evaluated the coupled continuum pipe-flow framework for modeling karst groundwater flow in the Madison aquifer of western South Dakota (USA). Coupled conduit and matrix flow was simulated within a regional finite-difference model over a 10-year transient period. An existing equivalent porous medium (EPM) model was modified to include major conduit networks whose locations were constrained by dye-tracing data and environmental tracer analysis. Model calibration data included measured hydraulic heads at observation wells and estimates of discharge at four karst springs. Relative to the EPM model, the match to observation well hydraulic heads was substantially improved with the addition of conduits. The inclusion of conduit flow allowed for a simpler hydraulic conductivity distribution in the matrix continuum. Two of the high-conductivity zones in the EPM model, which were required to indirectly simulate the effects of conduits, were eliminated from the new model. This work demonstrates the utility of the coupled continuum pipe-flow method and illustrates how karst aquifer model parameterization is dependent on the physical processes that are simulated.

A rare case of anomalous origin of the left main coronary artery in an adult patient

Anomalous origin of left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly that causes a left-to-right shunt via the coronary system, resulting in coronary steal. We report an unusual case of a healthy 48 years-old patient presenting with dyspnea on exertion and mild chest pain who underwent surgical correction of this rare anomaly. Multiple procedures have been proposed in adults with ALCAPA. Although re-implantation of the left main coronary artery (LMCA) to the aorta remains the most physiological correction for this anomaly, the combination of LMCA ligation and coronary artery bypass grafting provides a dual coronary flow system and is preferable when re-implantation is impossible.

Evaluation of a stratified continuous rumen incubation system

We present a continuous culture system based on one developed by [Teather, R.M., Sauer, F.D., 1988. A naturally compartmented rumen simulation system for the continuous culture of rumen bacteria and protozoa. J. Dairy Sci. 71, 666–673]. In which programmable stirring speeds allow a raft mat to form similar to that found in the rumen to produce a de facto dual flow system with different liquid and solid turnover rates that helps to maintain the protozoal population. Novel features include a non-clogging outflow, and a computer controlled, compact feeding system able to deliver ground substrates or pellets. The system comprises 12 thermostat controlled fermenter vessels with a working volume of 1 L each. The fermenters were primed with rumen fluid from two cows and continuously provided with the same diet as the donor animals (15 g/day for 3 days then 10 g/day) and artificial saliva (1 L/day). The concentration of short chain fatty acids (SCFA), microbial ribosomal RNA (rRNA) concentrations and total enzymatic activities were all lower in the fermenter than in the donor animals, but the proportions of SCFA remained the same. There was no difference in specific cellulase activity, but specific xylanase activity and total protozoal counts were significantly higher in the fermenters. The proportions of Bacteria, and Eukaryota (i.e., protozoa and fungi) were similar in the fermenters compared to the donor animal, but the proportion of the Archaea (methanogens) was increased. Total rRNA from cellulolytic organisms ( Chytridiomycetes, Fibrobacter sp. Ruminococcus albus and R. flavefaciens) was similar to that in the donor animals. However, the composition of the cellulolytic community changed with the proportion of R. albus and the Chytridiomycetes increasing while the proportion of R. flavefaciens decreased, and the genus Fibrobacter was unchanged. Despite these differences, this in vitro system has potential to study effects of feed components on fermentation parameters. Whether the system will prove useful for modelling changes in the composition of the rumen microbial community needs to be evaluated further.

Micro-gas analysis system for measurement of nitric oxide and nitrogen dioxide: Respiratory treatment and environmental mobile monitoring

In this paper, novel microsystems for gas analysis and gas generation are described. The same microchannel devices covered with a gas permeable membrane were used for both the gas collection and the gas generation. For the first time, a dual liquid flow system was utilized in a micro-gas analysis system. Even though micropumps are utilized in the dual line microsystem, a good baseline was obtained in the NO 2 measurement with Griess–Saltzman chemistry. The system was developed for on-site measurements in medical treatment; the treatment is of respiratory disease syndrome by NO inhalation and the monitoring is of the product NO and the harmful byproduct NO 2. The system was also applied to mobile atmospheric monitoring. Chemical NO generation using the microchannel device was investigated for safe NO inhalation as an alternative to a NO generator based on pulsed arc discharge.

Assessment of the Effects of Cinnamon Leaf Oil on Rumen Microbial Fermentation Using Two Continuous Culture Systems

Two continuous culture (CC) systems, the rumen simulation technique (Rusitec) and a dual-flow (DF) fermenter, were used to evaluate effects of the essential oil from cinnamon leaf (CIN) on rumen microbial fermentation. Incubations (d 1 through 8 for adaptation and d 9 through 16 for sampling) were conducted concurrently in the 2 systems, with CIN added at 0 (control) and 500 mg/L of rumen fluid culture. Eight Rusitec (920mL; dilution rate = 2.9%/h) and 6 DF (1,300mL; dilution rate = 6.3%/h) fermenters were randomly assigned to treatment. Inoculum was prepared from 4 ruminally cannulated lactating Holstein cows fed a total mixed ration consisting of 51% forage and 49% concentrate (dry matter basis). Ruminal pH, total volatile fatty acid (VFA) concentration, and diet digestibility were reduced by CIN addition in the Rusitec but were not affected by CIN administration in the DF. The addition of CIN in the Rusitec decreased apparent N disappearance, NH3-N concentration, and molar proportions of branched-chain VFA. In contrast, in the DF no effect of CIN was observed on apparent N degradation, NH3-N concentration, and molar proportion of branched-chain VFA. In the Rusitec, the molar proportion of acetate was similar between treatments on d 9 and 13, but was lower from d 10 to 12 and higher on d 14 to 16 with CIN than with control (interaction of treatment×sampling day). The molar proportion of acetate remained unaffected by CIN addition in the DF. In both CC systems, the molar proportion of propionate was decreased whereas that of butyrate was increased by CIN addition. In the DF, CIN decreased microbial N flow and efficiency of microbial protein synthesis. Protozoa numbers were lower with CIN than with control in both CC fermenters. In the Rusitec, CIN increased 15N enrichment in total bacterial fractions, but no effect was observed on the production of microbial N. This study showed that CIN exhibited antimicrobial activity in both CC systems, but the effects were more pronounced in the Rusitec than in the DF system. These differences are likely a reflection of the higher dilution rate in the DF resulting in a lower effective concentration of CIN than in Rusitec. Based on these changes in rumen microbial fermentation, supplementation of CIN at the concentration evaluated in this study may not be nutritionally beneficial to ruminants.