Instantaneous Temperature Measurements Research Articles

Development of a micro-infrared thermometry method for surface temperature distribution and variation of millimeter particle during high-temperature reaction

Temperature strongly affects the conversion efficiency, local reactivity, and particle stabilization of the reactions, particularly at high temperature. This study integrated infrared thermography with a high-temperature hot stage reactor to develop a methodology of continuous temperature measurement for a single particle reaction at high temperatures. The external optical transmission transmittance and temperature field core were corrected, and the relationship between the measured temperature (Tr) and true temperature (T0) was obtained by adjusting the sample emissivity. Sample temperature with known emissivity at elevated temperature was measured with 1% deviation. The instantaneous temperature measurement for the gasification process was carried out and the overall emissivities of coal particles were corrected. Temperature distribution and variation on the coal particle surface during the gasification process were further obtained and consistent with the previous research results. The proposed online temperature measurement method provides a new approach for gaining insights into particle reaction states.

Parametric study of intensity-ratio-based phosphor thermometry using Mg4FGeO6:Mn4+ for instantaneous temperature measurement

Intensity-ratio-based phosphor thermometry is advantageous for instantaneous temperature measurement because it avoids interframe displacement due to moving phosphor coated samples that is encountered with lifetime-based methods. This study was aimed at investigating the effects of exposure time, excitation energy, and wavelength on intensity-ratio-based phosphor thermometry using Mg4FGeO6:Mn4+ (MFG). First, the temperature-dependent emission spectra of MFG were obtained under 355 nm and 405 nm excitations. The spectra exhibited different trends in the two cases, potentially because of thermally enhanced phonon-assisted absorption. Next, the shot-to-shot calibration uncertainties were evaluated from the temperature calibration results under different exposure time and excitation irradiance/fluence values for light-emitting diode/laser. The uncertainties under 355 nm and 405 nm excitations exhibited similar trends, i.e. they increased and decreased with increasing temperature and exposure time, respectively. For the minimum exposure time of 4 μs under 355 nm excitation, the uncertainty increased from 1.5 K at 323 K to 3.3 K at 673 K at a constant excitation fluence of 3.14 mJ cm−2. The uncertainties under 405 nm excitation were higher than those under 355 nm excitation. In addition, the inaccuracies due to excitation non-uniformity were evaluated from the calibration results under different excitation irradiance/fluence. The calibration curves were more sensitive to excitation irradiance at higher temperatures under 405 nm excitation. Consequently, the excitation non-uniformity induced inaccuracies under 405 nm excitation and different exposure time values were small at low temperatures (0.4–1.1 K at 323 K) and increased rapidly with temperature (2.6–14.4 K at 673 K). In the case of 355 nm excitation, the calibration curves exhibited small sensitivity to excitation fluence only at low temperatures. As the temperature increased, the inaccuracies under 355 nm excitation decreased and then increased, and exhibited values between 0.5 K and 2.5 K.

A Microwave Stripline Ring Resonator Sensor Exploiting the Thermal Coefficient of Dielectric Constant for High-Temperature Sensing

A stripline transmission-line (TL)-based temperature sensor for use in harsh environments is designed to exploit the thermal coefficient of the dielectric constant (TCD) of the microwave (MW) substrate material. Rogers 3210 substrate is selected owing to its high TCD of −459 ppm/°C and a dielectric constant of 10.8. A ring resonator is designed for 2.4 GHz, with the ring selected for the simple geometric dependence of its resonant frequency on radius. TLs are gap-coupled to the ring, with widths designed for 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> impedance matching and lengths optimized for a compact form factor. Upper and lower ground planes shield the dielectric, resonator, and TLs from environmental disturbances, such as debris and moisture, which could otherwise disrupt temperature measurement. Furthermore, the electric field is completely contained within the homogeneous dielectric, providing improved sensitivity compared to similar designs using microstrip technology. The fabricated sensor requires uniform compression of layers to mitigate the effects of air pockets and thermal expansion of materials. It is found that the sensor requires temperature-conditioning, approximately 70 h cycling between 30 °C and 80 °C, before its resonant frequency reaches a steady state suitable for instantaneous temperature measurement. Subsequent 10 °C- and 2 °C-step experiments are performed in the 30 °C–80 °C and 30 °C–40 °C ranges, respectively. As a result, a linear sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx 500$ </tex-math></inline-formula> kHz/°C is identified. The duration of these experiments and time-based data are representative of applications where long-term temperature monitoring is required.

Time-resolved multi-parameter flow diagnostics by filtered Rayleigh scattering: system design through multi-objective optimisation

The measurement of the time-resolved three-component (3C) velocity field together with scalar flow quantities such as temperature or pressure by laser-optical diagnostics is a challenging task. Current approaches usually employ combinations of different methods relying on tracer particles or molecules. This typically requires usage of at least two laser systems and detection units as well as elaborate calibration of the luminous properties of the applied tracer species with regard to the specific thermodynamic conditions anticipated for the flow case at hand. In contrast to this, the tracer-free filtered Rayleigh scattering (FRS) technique has been proven to obtain combined time-averaged velocity and scalar fields and might offer a viable alternative for unsteady flow diagnostics. By applying multiple perspective views, two detection system variants are presented, combining (1) six observation branches with one camera/molecular filter and (2) three camera views with two cameras and molecular filters of differing vapour densities. Both configurations in principle allow for the simultaneous measurement of instantaneous 3C velocity, temperature and pressure fields. Multi-objective optimisation is used to enhance the detection setups for different sets of experimental configurations. It is shown that a higher number of observation positions and the associated dynamics of the FRS signal prove to be advantageous compared to the use of less views in combination with two acquisition channels equipped with different molecular filters. It is also shown that the use of circularly polarised laser light offers no advantage over linear polarisation. By demonstrating a moderate sensitivity of the optimised observation arrangement to alignment errors, the presented FRS concept provides a practical solution for the simultaneous measurement of time-resolved 3C flow velocity and scalar fields.

Unsteady Multi-Parameter Flow Diagnostics By Filtered Rayleigh Scattering: System Design By Multi-Objective Optimisation

The measurement of the time-resolved three-component (3C) velocity field together with scalar flow quantities such as temperature or pressure by laser-optical diagnostics is a challenging task. Current approaches typically employ combinations of different methods relying on tracer particles or molecules, which requires elaborate calibration procedures of the tracer's photo-physical properties and extensive instrumentation. In contrast to this, the tracer-free filtered Rayleigh scattering (FRS) technique has been proven to obtain combined time-averaged velocity and scalar fields and might offer a viable alternative for unsteady flow diagnostics. By applying multiple perspective views, two detection system variants are presented, combining 1) six observation branches with one camera/molecular filter and 2) four camera views with two cameras and molecular filters of differing vapour densities. Both configurations in principle allow for the simultaneous measurement of instantaneous 3C velocity, temperature and pressure fields. Multi-objective optimisation is used to enhance the detection setups for different sets of experimental configurations. It is shown that a higher number of observation positions and the associated dynamics of the FRS signal prove to be advantageous compared to the use of less views in combination with two acquisition channels equipped with different molecular filters. It is also demonstrated that the use of linearly polarised laser light is preferred over circular polarisation. Future work will focus on the realisation of the multiple-view FRS concept for the combined measurement of 3C velocity and scalar fields.

New Insights into Abnormal Combustion Phenomena Induced by Diesel Spray-Wall Impingement under Engine-Relevant Conditions

High altitude and low temperature is the common extreme environment for internal combustion engines. Under such operating conditions, heavy-duty diesel engines often suffer from serious abnormal combustion, such as knocking combustion, which results in piston crown breakdown and cylinder head erosion. Spray-wall impingement and pool fires are considered potential causes; however, the detailed mechanism remains poorly understood owing to the lack of research data. In this study, for the first time, the destructive abnormal combustion induced by diesel spray-wall impingement was identified using an optical rapid compression machine under engine-relevant conditions at high altitudes. Combining instantaneous pressure and temperature measurements with simultaneously recorded high-speed photography gives useful insights into understanding the detailed combustion processes. The experimental results show that depending on the extent of diesel spray-wall impingement, supersonic detonation-like reaction fronts featuring bright luminosity can be observed. The propagation of these reaction fronts in-cylinder results in severe pressure oscillations with an amplitude approaching hundreds of atmospheres, which is like the super-knock events in boosted direct-injection spark-ignition engines. Further parametric analysis indicates that the interplay between the diffusion combustion controlled by diesel spray and the premixed combustion dominated by attached film evaporation results in the formation of abnormal combustion. Destructive reaction fronts tend to occur at a prolonged ignition delay time, which facilitates the mixing between diesel evaporation and hot air.

Experimental testing on the influence of shaft rotary lip seal misalignment for a marine hydro-kinetic turbine

Tidal energy has received considerable attention over the past decade due to its predictability and high power density. The research in the tidal turbine area has concentrated primarily on the improvement of the energy conversion efficiency. In contrast, the testing of the tidal turbine’s mechanical components has received less attention. In particular, the reliable operation of rotary seals is crucial to prevent water ingress into mechanical and electrical components. This paper outlines an experimental test campaign to investigate the effect of shaft misalignment. Both instantaneous temperature and pressure measurements were recorded from two rotary seals. It was shown the temperature inside the aligned seal increased until the seal chamber pressure became equal with the inlet water pressure. The wear on the lip seal rings was examined and the difference found to be between 3.28% and 19.61%. Inspection of the seal liners, showed the presence of strong wiping effects for the misaligned seal with maximum track width differences of between 52.94% and 97.60% being noted. The misaligned seal liner experienced wider wear tracks but were not as deep as the aligned seal with differences of between 37.55% and 103.13% being recorded.

Ignition characteristics of premixed cool flames on a heated wall

This work examined the cool flame ignition and stabilization on heated walls with different surface reactivities. A premixed mixture of dimethyl ether (DME) and O2 was impinged on a heated wall and the wall temperature was linearly ramped to determine the cool flame ignition temperature. Numerical analyses identify a hysteresis phenomenon in the cool flame ignition and extinction processes, which appears to be primarily governed by the low-temperature reaction kinetics. The formation of HCHO during the cool flame ignition process was monitored using the planar laser-induced fluorescence (PLIF) technique synchronized with instantaneous wall temperature measurements. The data indicated that the HCHO concentration near the wall surface abruptly increased at the ignition of the premixed cool flame. The predicted hysteresis behaviors for cool flame ignition and extinction with a nonlinear folded S-curve and a smoothly stretched S-curve were successfully observed experimentally for the first time ever for lean mixtures. Moreover, the results show that compared with the ignition limits on an inert SiO2 surface, noticeable increases and decreases of the cool flame ignition temperature were observed on Fe and Pt surfaces, respectively. These findings suggest that significant wall chemical effects occur during the cool flame ignition process, based on interactions between the gas phase and surface reactions.

Estimation of Aerodynamic and Canopy Resistances in a Mediterranean Greenhouse Based on Instantaneous Leaf Temperature Measurements

Aerodynamic and canopy resistances have long been considered to be of key interest in model equation parameterization, particularly for the accurate estimation of crop evapotranspiration. However, model parameters applied in greenhouses showed variation affected by the micrometeorological environment. Three experiments were carried out in a plastic greenhouse to evaluate microclimate effects on resistances of a soilless cucumber crop. The regression analysis of canopy-to-air temperature (Tc − Ta) difference on air vapor pressure deficit (VPD) was substituted into the energy balance equation for the estimation of aerodynamic and canopy resistance values. As expected, a fan and pad evaporative cooling system proved to be the more efficient method of decreasing crop temperature (Tc) compared to the forced air ventilation system. The estimated transpiration by the Penman–Monteith model based on calculated aerodynamic and canopy resistance values successfully validated values measured with lysimeters in different growing periods. In this article, we report for the first time the calculation of aerodynamic and canopy resistance values inside a greenhouse based on equations for an open field that were found in the literature. Results may be helpful in Mediterranean greenhouses for direct determinations of plant water evaporative demand and smart climate control systems.

Laminated Ag and Ag/CNT nanocomposite films as sensing element for efficient thin film temperature sensors

Thin film sensor (TFS) is one of the most promising candidates for instantaneous temperature measurements owing to their extremely small response time (~milliseconds) aided with fair accuracy. Since they are capable of making quick and precise temperature measurements, they can be also used as heat flux gauges to measure surface heat fluxes in dynamic environments like high speed aerospace applications, gas turbine blades etc. Usual TFS are made by depositing a thin metallic film over insulating substrate. In this work we developed an Ag-Carbon nanotube (CNT) nanocomposite film as the sensing element of a TFS and compare it with pure Ag TFS, both having Macor as substrate. Static calibration established a better temperature coefficient of resistance (TCR) value i.e. better sensitivity, for the nanocomposite TFS. X-ray diffraction (XRD) and Energy Dispersive X-ray (EDX) studies are done to probe behind the increase in sensitivity of the nanocomposite TFS compared to its conventional metallic counterpart.

Convection velocity of temperature fluctuations in a natural convection boundary layer

Measurements of instantaneous temperature are carried out in a natural convection boundary layer (NCBL) developing over a vertical hot plate using a combination of an infra-red sensor, three cold-wire probes and a Resistance Temperature device (RTD). The aim of this study is to establish experimental procedures for high spatial and temporal resolution temperature measurements, and use that information to measure the convective speed of thermal structures in the flow. The evolution of NCBL along the hot plate is compared against existing empirical models. Statistics of mean and fluctuating temperature are in excellent agreement with the previously reported experimental data for a turbulent NCBL. The boundary layer thickness is observed to grow as y0.45, where y is the vertical distance along the heated plate. Separate experiments are conducted by varying the heat input to investigate its effect on convection velocity (Uc) of thermal structures in the flow. It is found that Uc remained nominally constant in the region 0 ≤ x ≤ δT/2 (δT is the thickness of thermal boundary layer) and decreased in a log-linear fashion in the outer region of NCBL. The results of Uc are found to be consistent with the shadowgraph measurements carried out in the same test rig, and the normalised convection velocity, Uc*=UcδTν is found to depend on Rayleigh number as Uc*∝Ra0.82, where ν is the kinematic viscosity of air. Importantly, these experimental observations are in agreement with the three layer model put forth by Wells and Worster (2008).

A framework for data-based turbulent combustion closure: A posteriori validation

In this work, we demonstrate a framework for developing closure models in turbulent combustion using experimental multi-scalar measurements. The framework is based on the construction of conditional means and joint scalar PDFs from experimental data based on the parameterization of the composition space using principal component analysis (PCA). The resulting principal components (PCs) act as both conditioning variables and transported variables. Their chemical source terms are constructed starting from instantaneous temperature and species measurements using a variant of the pairwise mixing stirred reactor (PMSR) approach. A multi-dimensional kernel density estimation (KDE) approach is used to construct the joint PDFs in PC space. Convolutions of these joint PDFs with conditional means are used to determine the unconditional means for the closure terms: the mean PCs chemical source terms and the density. These means are parameterized in terms of the mean PCs using artificial neural networks (ANN). The framework is demonstrated a posteriori using the data from the Sandia piloted turbulent jet flames D, E and F by performing RANS calculations. The radial profiles of mean and RMS of temperature and measured species mass fractions agree well with the experimental means for these flames.

Temperature measurements along a vertical borehole heat exchanger: A method comparison

The standard thermal response tests (TRT) provide integral and effective thermal parameters of the ground in the vicinity of borehole heat exchangers (BHE). However, typical ground properties are heterogeneously distributed. As a result, advanced TRT such as distributed and enhanced TRT are growing in popularity as they provide more spatial information of the thermal properties. Thus, the objective of this study is to compare various instruments to measure the depth-dependent temperatures using standard Pt100-sensors, fiber optical thermometers and novel instruments such as Geowire, Geoball and GEOsniff®. The investigations are carried out in a 30 m length test borehole. The results showed an excellent agreement between both the Geowire and GEOsniff® in comparison with Pt100-sensors with a root mean squared error of 0.10 and 0.09 K, respectively. The results also suggest that the novel instruments have various advantages over the standard sensors and fiber optics. For example, with the novel instruments comparable, accurate, inexpensive, instantaneous and higher spatial resolution temperature measurements are obtained. Finally, the outcome of this study provides a guide for choosing the adequate temperature measurement along a BHE thus generally improving the evaluation of advanced TRT, while potentially increasing efficiency and economic viability of ground-source heat pump systems.

Heat flux measurement analysis from thin film gauge in convective heat transfer mode

In many research activities related to the heated environment near the wall or surface, measurement of transient surface temperature and determination of convective heating rate is one of the most important tasks. Since the effective measurement time available for the regime to enumerate is very small, it is essential to use temperature detectors with highly sensitive, precise and instantaneous temperature measurement properties. Thin film gauges with these properties are best suited for such short duration transient surface temperature measurements. This study focuses on the establishment of new calibration technique in convection heat transfer mode. A fabricated calibration set-up is used to supply the heat flux to the thin film gauge, which is in-house built with platinum as sensing element and quartz as an insulating substrate. The heat load applied on the thin film gauge is of impact or step type. The deduction of heat flux value is carried out with recorded transient temperature data. Moreover, the numerical analysis is also carried out to get the heat flux values. The authenticity of the experimental set up and thin film gauge effectiveness is supported by the excellent agreement of the experimental and numerical results.

Instantaneous Surface Temperature Measurement by Coaxial Type Thin-film Temperature Sensor and Derivation of Local Heat Flux Using Measured Values

Instantaneous Surface Temperature Measurement by Coaxial Type Thin-film Temperature Sensor and Derivation of Local Heat Flux Using Measured Values

Laser intensity and absorbance measurements by tunable diode laser absorption spectroscopy based on non-line fitting algorithm

A novel approach to using tunable diode laser absorption spectroscopy (TDLAS) is developed for measuring the laser intensity and absorbance of gas with highly broadened and congested spectra by wavelength division multiplex (WDM) technology. Direct absorption spectroscopy with non-linear algorithm is utilized, because this fitting method offers benefits in dealing with blended spectral features according to the relationship between transmitted laser intensity and absorbance by Beer law. Compared with traditional TDLAS sensing with WDM, this approach has some advantages of transmissions demultiplexing without additional optic gratings and detectors. Following the published theory, the absorbance and transmitted laser intensity are incorporated into an improved non-linear fitting model. A solution to a simulation of CO2 blended spectrum at a pressure of 5 atm is exploited to demonstrate the ability to recover the absorption in a high pressure environment, inferring the optimal combination of parameters in the model. The influences of these nonideal laser effects, such as nonlinear and linear coefficients, are investigated by the multiplexed transmission simulations at rovibrational transitions of H2O near 7444 cm-1 and 7185 cm-1. Errors in absorbance fitting is larger when nonlinear or linear coefficients of two lasersbecome closer. The satisfied results can be obtained when linear coefficients ratio is limited whitin a range from 0.05 to 0.67. In addition, the essential transition spacing in multiplexed transmissions, larger than the full width of transitions, is considered to be able to improve the fitting accuracy. This approach is validated in a static absorption cell over a pressure range from 1 to 10 atm at room temperature to demonstrate the ability to measure the blended CO2 spectrum from 63307 cm-1 to 6337 cm-1 by a single DFB laser. The sensor method resolves laser intensity with a nonlinear coefficient of 1.4×10-4 and recovers absorbance with a root mean square (RMS) precision of 3.2%, which demonstrates the applicability of this sensor to high-pressure gas sensing systems. Another approach to validating the gas temperature and measuring H2O by WDM is presented in a gas-liquid two phase pulsed detonation engine running with a filling fraction of 100%. Two fiber coupled lasers, respectively, near 7185.6 cm-1 and 7444.35 cm-1 are scanned at 20 kHz to achieve a temporal resolution of 50 μs for monitoring detonation exhaust. A fixed spectrum interval (about 0.7 cm-1) of transitions in multiplexed transmission is created through temperature adjustment in DFB laser to provide more independent absorption information. Recovered linear coefficients of 0.18 and 0.46 in two DFB lasers are in good agreement with the results from the simulations. An instantaneous temperature measurement of 1183 K in the exhaust 7.45 ms after detonation wave provides the confirmation of the ability of this method to infer the temperature and H2O time histories in the whole detonation process. In conclusion, the novel approach based on TDLAS has tremendous potential applications in high pressure combustion diagnosis and WDM spectrum analysis.

Wide range instantaneous temperature measurements of convective fluid flows by using a schlieren system based in color images

In the schlieren method, the deflection of light by the presence of an inhomogeneous medium is proportional to the gradient of its refractive index. Such deflection, in a schlieren system, is represented by light intensity variations on the observation plane. Then, for a digital camera, the intensity level registered by each pixel depends mainly on the variation of the medium refractive index and the status of the digital camera settings. Therefore, in this study, we regulate the intensity value of each pixel by controlling the camera settings such as exposure time, gamma and gain values in order to calibrate the image obtained to the actual temperature values of a particular medium. In our approach, we use a color digital camera. The images obtained with a color digital camera can be separated on three different color-channels. Each channel corresponds to red, green, and blue color, moreover, each one has its own sensitivity. The differences in sensitivity allow us to obtain a range of temperature values for each color channel. Thus, high, medium and low sensitivity correspond to green, blue, and red color channel respectively. Therefore, by adding up the temperature contribution of each color channel we obtain a wide range of temperature values. Hence, the basic idea in our approach to measure temperature, using a schlieren system, is to relate the intensity level of each pixel in a schlieren image to the corresponding knife-edge position measured at the exit focal plane of the system. Our approach was applied to the measurement of instantaneous temperature fields of the air convection caused by a heated rectangular metal plate and a candle flame. We found that for the metal plate temperature measurements only the green and blue color-channels were required to sense the entire phenomena. On the other hand, for the candle case, the three color-channels were needed to obtain a complete measurement of temperature. In our study, the candle temperature was took as reference and it was found that the maximum temperature value obtained for green, blue and red color-channel was ∼275.6, ∼412.9, and ∼501.3°C, respectively.

Multiscale statistical analysis of the tin-lead alloy solidification process

This paper presents a quasi-two-dimensional solidification benchmark experiment with controlled thermal boundary conditions. The experiment consists in solidifying a rectangular ingot of Sn-3wt.%Pb using two lateral heat exchangers to extract the heat flux from one or both vertical sides of the sample. The aim is to assess the reproducibility of the solidification experiments performed under rigorously identical conditions. The temperature difference (ΔT) between the two vertical sides is 40 K and the cooling rate (CR) is 0.03 K/s. This slow-cooling condition favours segregation formation. A lattice of fifty thermocouples placed on the front of the sample between the two vertical sides is used to determine the instantaneous temperature distribution. During solidification, the time evolution of the temperature field is recorded and analyzed. This allows us to estimate the time evolution of the temperatures due to natural convection and assess the velocity field, the solidification macrostructure and the segregation behaviour. Post-mortem segregation patterns are obtained both by X-ray radiography and induction coupled plasma analysis. The recorded data is analyzed statistically. An ensemble average procedure is applied to both instantaneous temperature and post-mortem composition measurements. This makes it possible to determine the mean values of the solidification parameters as well as their standard deviations. Temperature fluctuation standard deviations are deterministic and characterize the solidification dynamics. Among other results, it is shown that mesoscale segregation locations are not fully predictable.

Nanosecond-resolved temperature measurements using magnetic nanoparticles.

Instantaneous and noninvasive temperature measurements are important when laser thermotherapy or welding is performed. A noninvasive nanosecond-resolved magnetic nanoparticle (MNP) temperature measurement system is described in which a transient change in temperature causes an instantaneous change in the magnetic susceptibilities of the MNPs. These transient changes in the magnetic susceptibilities are rapidly recorded using a wideband magnetic measurement system with an upper frequency limit of 0.5 GHz. The Langevin function (the thermodynamic model characterizing the MNP magnetization process) is used to obtain the temperature information. Experiments showed that the MNP DC magnetization temperature-measurement system can detect a 14.4 ns laser pulse at least. This method of measuring temperature is likely to be useful for acquiring the internal temperatures of materials irradiated with lasers, as well as in other areas of research.

Towards optimal operation of sequential NOx storage and reduction and selective catalytic reduction

Combined NOx storage and reduction (NSR) and selective catalytic reduction (SCR) were conducted in a bench flow reactor comprising a Pt/Rh/BaO/Al2O3 lean NOx trap (LNT) catalyst and either Fe-ZSM-5 or Cu-SSZ-13 SCR catalyst. Simulated exhaust gas containing C3H6 or CO reductant was used to evaluate catalyst performance in terms of cycle-averaged NOx conversion and product selectivities over a range of feed concentrations and temperatures, and gas hourly space velocities (GHSV). Instantaneous concentration and temperature measurements reveal strong coupling of mass and energy between the LNT and SCR. The data show the importance of NH3 generation by the LNT for effective use of the downstream SCR. Operating conditions are identified that maximize utilization of the downstream SCR. A non-NH3 SCR pathway is found to be significant for Cu-SSZ-13 at intermediate temperature and high space velocity. The post-LNT NH3 to NOx ratio (ANR) correlates with the incremental NOx conversion achieved for Fe-ZSM-5, noting that ANR ∼1 favors NH3-based standard SCR at high conversion. A reactor system productivity metric for N2 generation (space-time yield analog) is used to rank-order the LNT+SCR systems and together with the propylene conversion are used to identify conditions giving the best performance. The combination of an overall GHSV of 135kh−1 and 350°C feed temperature generates a SCR feed from the LNT that results in the highest incremental cycle-averaged NOx conversion in the SCR (∼30% with Cu-SSZ-13) and high cycle-averaged conversions of NOx (∼90%) and propylene (∼80%). The Cu-SSZ-13 out-performs the Fe-ZSM-5 catalyst under most conditions.