Instantaneous Heat Release Rate Research Articles

Study on combustion and emission characteristics of a n-butanol engine with hydrogen direct injection under lean burn conditions

The n-butanol fuel, as a renewable and clean biofuel, could ease the energy crisis and decrease the harmful emissions. As another clean and renewable energy, hydrogen properly offset the high HC emissions and the insufficient of dynamic property of pure n-butanol fuel in SI engines, because of the high diffusion coefficient, high adiabatic flame velocity and low heat value. Hydrogen direct injection not only avoids backfire and lower intake efficiency but also promotes to form in-cylinder stratified mixture, which is helpful to enhance combustion and reduce emissions. This experimental study focused on the combustion and emissions characteristics of a hydrogen direct injection stratified n-butanol engine. Three different hydrogen addition fractions (0%, 2.5%, 5%) were used under five different spark timing (10° ,15° ,20° ,25° ,30° CA BTDC). Engine speed and excess air ratio stabled at 1500 rpm and 1.2 respectively. The direct injection timing of the hydrogen was optimized to form a beter stratified mixture. The obtained results demonstrated that brake power and brake thermal efficiency are increased by addition hydrogen directly injected. The BSFC is decreased with the addition of hydrogen. The peak cylinder pressure and the instantaneous heat release rate raises with the increase of the hydrogen addition fraction. In addition, the HC and CO emissions drop while the NOx emissions sharply rise with the addition of hydrogen. As a whole, with hydrogen direct injection, the power and fuel economy performance of n-butanol engine are markedly improved, harmful emissions are partly decreased.

Engine performance, combustion and emission characteristics of a compression ignition engine operating on different biodiesel-alcohol blends

A numerical simulation has been carried out in this work to evaluate the performance, combustion and emission characteristics of a compression ignition engine using different biodiesel-alcohol blends as fuels. A single cylinder, four stroke, naturally aspirated, direct injection diesel engine is chosen for the simulation work using the commercial software Diesel-RK. The effects of two alcohols, namely ethanol and methanol addition to palm stearin biodiesel have been separately investigated and compared. The predicted results show slightly higher brake specific fuel consumption as well as brake thermal efficiency with biodiesel-alcohol blends compared to neat biodiesel. An effective reduction of NOx emission is also observed with the biodiesel-alcohol blends. However, the instantaneous heat release rate, ignition delay, PM and smoke emission are found to be more with alcohol blended fuels.

A numerical study on the performance, combustion and emission parameters of a compression ignition engine fuelled with diesel, palm stearin biodiesel and alcohol blends

A numerical simulation has been carried out in this study to evaluate the effect of alcohol addition to the blends of diesel and palm stearin biodiesel on the performance, combustion and emission of a diesel engine. The commercial software Diesel-RK has been used in this study to simulate a single-cylinder, naturally aspirated, direct injection, four-stroke diesel engine. The simulated results have been validated against experimental observation for the base fuel diesel. The effects of two alcohols, namely ethanol and methanol have been separately investigated and compared. The results indicate that although the brake-specific fuel consumption is slightly increased, the other performance characteristics and the entire combustion and emission parameters are improved with alcohol addition to diesel–biodiesel blends. The instantaneous heat release rate, ignition delay and oxides of nitrogen emission are found to be more with methanol than with ethanol. The diesel–biodiesel blend also shows better combustion and emission characteristics than that of diesel except oxides of nitrogen emission.

Effect of spark timing on combustion and emissions of a hydrogen direct injection stratified gasoline engine

The effect of spark timing on combustion and emissions of a hydrogen direct injection stratified gasoline engine was investigated. The engine was operated at 1500 rpm and excess air ratio at 1.2. It was found that when the hydrogen volume fraction was raised from 0% to 10%, and the hydrogen injection timing was 110 °CA BTDC a good stratified effect was achieved. The spark timing was varied from 4 to 16 °CA BTDC. This test demonstrated that the brake thermal efficiency first rose and then fell with the spark advance angle increased. In addition, it increased with the increase of hydrogen volume fraction. Postponing the spark timing caused the maximum instantaneous heat release rate increase. The peak cylinder pressure and the maximum rate of pressure rise increased with spark advance angle increase. Postponing the spark timing also caused NOx, HC and CO emissions to decrease. When the hydrogen volume fraction increased, the NOx emissions rose and the HC and CO emissions dropped.

Effects of stratification on locally lean, near-stoichiometric, and rich iso-octane/air turbulent V-flames

The effects of partial premixing on locally rich, near-stoichiometric, and lean flame regions were investigated in stratified, iso-octane/air turbulent V-flames by varying the mean equivalence ratio gradient along the exit plane of a rectangular slot burner. Instantaneous heat release rate (HRR) images were obtained from the product of spatially registered, near-simultaneously acquired OH and CH2O planar laser induced fluorescence (PLIF) images. HRR data were analyzed within a region of interest (ROI) that was determined from separate 3-pentanone tracer PLIF measurements. The ROI was unique to each gradient flame setting, and was configured to ensure the mean range of equivalence ratios being analyzed was constant among gradient conditions. This allowed distinction of the effects of mean equivalence ratio gradient at the flame front from effects associated with having different ranges of equivalence ratios within the flame zone.Individual flame realizations were studied for differences in the local peak HRR and instantaneous flame thickness δt as they varied with curvature among gradient conditions. While general trends for the fully-premixed cases were consistent with Lewis number theory, subtle changes in the normalized distribution of local peak HRR vs. curvature were observed for locally rich and locally lean flames propagating in different mean ϕ gradients. Negligible changes were observed for near-stoichiometric flames, suggesting that gradient effects may influence the local thermodiffusive stability of off-stoichiometric mixtures more significantly.Ensemble averages of individual peak HRR and δt values within each ROI were separately evaluated, and differences among gradient conditions were greater than those observed for the normalized distributions with curvature. For all flame settings considered, an increase in either of the peak HRR or δt led to a decrease in the other. Gradient effects were observed when comparing back- and front-supported locally rich flames, which experienced opposite changes in peak HRR of +10.1% and −5.2% for gradient settings ∂ϕ/∂y = −0.014 mm−1 and ∂ϕ/∂y = 0.012 mm−1 respectively, coupled with a thinning and thickening of δt of −7.2% and +2.4%. Similar but weaker trends were observed for near-stoichiometric flame regions, with a decrease in peak HRR of up to −3.5% and a thickening up to +2.8% for the steepest gradient ∂ϕ/∂y = 0.029 mm−1. Locally lean flames showed small increases in peak HRR of up to +3.8%, and decreases in δt of up to −2.1% for back-supported gradient case ∂ϕ/∂y = 0.024 mm−1, however, variations were not as significant as those observed for back-supported rich flame regions of equivalent gradients. The presented results show that mean gradients of equivalence ratio can alter the local characteristics of partially premixed flames. Through subtle differences in the local distribution of peak HRR with curvature, more pronounced variations in the magnitude of the mean local peak HRR and δt, and opposing effects in both peak HRR and δt for back- and front-supported rich flames, the data reveal the specific influence of equivalence ratio gradients in experiments where the mean range of equivalence ratios in the analysis region is fixed.

Influence of fuel temperature on combustion and emission of biodiesel

To study the influence of fuel temperature on performances of biodiesel engine, combustion and emission performances of biodiesel engine at different fuel temperatures are tested and studied. It is found with the increase of fuel temperature, combustion pressure and instantaneous heat release rate curves leave far away from the top dead center and at high loads the combustion delays obviously; peak combustion pressure and peak instantaneous heat release rate decrease and at high loads the reduction increases; the backward combustion increases; at 1500 r/min, compared with 25 °C, NOX emissions of biodiesel at 40 °C and 55 °C averagely decrease by 7.6% and 9.1%, but smoke emissions averagely increase by 29.1% and 54.1%. Results indicate that fuel temperature has important influence on performances of biodiesel and it can be selected as a basic parameter to control the combustion and emission of biodiesel.

Combustion Characteristics and Cyclic Irregularity of an EFI Gasoline Engine Fueled with n-Butanol/gasoline Blends

An experimental study was conducted to evaluate the combustion characteristics of blends of n-butanol to gasoline with volume ratios of 0%, 20%, 50%, and 85% in addition to neat n-butanol on an electronic fuel injection (EFI) gasoline engine. Without any modifications to the original engine, the tests were carried out using the above five test fuels, with the engine working at maximum torque speed (3000 rpm) and four loads (25%, 50%, 75% and 100% of the maximum torque). The combustion characteristics including cylinder pressure, instantaneous and cumulative heat release were analysed. The test results show that all the peak values of cylinder pressure (CP), pressure rise rate (PRR), instantaneous heat release rate (IHRR) as well as total heat release of n-butanol/gasoline blends are lower than those of gasoline, and the higher the percentage of n-butanol is, the larger the reduction becomes. The crank angles of the peak values of CP, PRR and IHRR are larger than those of gasoline, whereas the crank angle of the total heat release is smaller than that of gasoline. The cyclic irregularity of n-butanol/gasoline bends is higher than that of gasoline. Therefore, the combustion of n-butanol/gasoline blends becomes mild, which further gives the benefit of reducing NOX emissions. However, the spark timing of the prototype should be advanced more in order to avoid power decreasing of n-butanol /gasoline blends.

Heat release rate variations in a globally stoichiometric, stratified iso-octane/air turbulent V-flame

Combustion intensity variations along a globally stoichiometric, stratified iso-octane/air turbulent V-flame were measured in the presence of four different equivalence ratio gradients and compared to a reference fully-premixed case. Instantaneous heat release rate (HRR) images were obtained from the simultaneous acquisition of OH and CH2O Planar Laser Induced Fluorescence (PLIF) images, providing the first direct estimates of local heat release rate in a stratified, iso-octane/air turbulent flame. Detailed numerical simulations were conducted to validate the use of (OH LIF)(CH2O LIF) for measurements of HRR in iso-octane/air flames over a broad range of equivalence ratios. Flame images were analyzed for specific mean equivalence ratio gradient effects for near stoichiometric flame regions within a fixed mean equivalence ratio range of 0.95⩽ϕ⩽1.05. The location of the interrogation window, or region of interest (ROI), was obtained through 3-pentanone tracer PLIF of the reactants and ensured that any observed variation could be attributed specifically to mean equivalence ratio gradient effects, rather than simple mixture strength effects. Results showed small but measurable, decreases in the mean HRR for near stoichiometric flame regions within the ROI as the gradient was varied, and differences of up to 4.4% relative to the reference premixed case were directly attributable to the imposed mean ϕ gradient, separate from potential effects of local mixture strength. By contrast, general stratification effects were also considered for flames of comparable global equivalence ratios but with much broader ranges of mixture strength, and results showed offsetting effects of increased 2D flame length (up to ∼17%) and decreased HRR per flame length (up to ∼22%), resulting in small variations in the overall HRR of ∼9%. The present analysis suggests that gradient effects on local flame properties may differ significantly from general stratification effects in which different ranges of mixture strengths are present, and separating these aspects of partially premixed combustion is critical to the proper interpretation of data, where both may be relevant in different applications.

Review of combustion characteristics of CI engines fueled with biodiesel

In this study, the combustion characteristics of CI engine with biodiesel–diesel blends and neat biodiesel are critically reviewed. Combustion parameters like cylinder pressure, peak pressure, rate of pressure rise, start of combustion, ignition delay period, combustion duration, mass fraction burned, instantaneous heat release rate and cumulative heat release rate of biodiesel blends and diesel have been reviewed. The difference in in-cylinder peak pressure between diesel and biodiesel blends is not significant and is within 1%. The ignition of the biodiesel is earlier than that of diesel by about 1–2° CA. Both diesel and biodiesel fuels experience rapid premixed burning followed by diffusion combustion as it is typical for naturally aspirated engines. The instantaneous and cumulative heat release rates of both fuels are quite close to each other. In general, the combustion characteristics of biodiesel fuel blends and neat biodiesel have resulted in the same characteristics as for normal diesel combustion. The results reviewed in this article indicate that biodiesel fuel blends and neat biodiesel can be used as an alternative and environment friendly fuels without any major modification of the CI engines.

The characteristic of polytropic coefficient of compression stroke in hydrogen internal combustion engine

The polytropic coefficient has important effect on the calculation of the instantaneous heat release rate and its comparison with specific heat ratio contains the information of the gas-surroundings heat exchange. This article studies the polytropic coefficient characteristics from 1000 rpm to 5000 rpm and the equivalence ratio from 0.24 to 0.55 by using experimental data from a 2.0 L hydrogen engine. The polytropic coefficient increase from 1.3 to 1.35 with the increase of engine speed from 1000 rpm to 4000 rpm, and then it decrease to around 1.34. This characteristic can be used to calculate the heat release rate more accurately. The study of the effect of equivalence ratio suggested that the polytropic coefficient decreased with the increase of equivalence ratio. The polytropic coefficient of hydrogen engine ranges from 1.28 to 1.35, which is less than the gasoline of 1.32–1.4. And the rising period of polytropic coefficient of ‘hydrogen – 0.55’ at 4500 rpm is very longer than others, which showed that the gases properties had effect on the heat transfer. These characteristics could not only be used for heat transfer calculation, but they can also enrich the research of polytropic coefficient for hydrogen internal combustion engine.

Physicochemical Properties, Combustion and Emission Performance of a Novel Zanthoxylum Bungeanum Seed Oil Methylic Ester Biodiesel

Zanthoxylum bungeanum seed oil methylic ester (ZSOME) biodiesel was synthesized through transesterification with Zanthoxylum bungeanum seed oil (ZSO) and methanol. The new biodiesel was characterized by Fourier Transform Infrared Spectroscopy and Gas Chromatography–Mass Spectrography. Physical chemistry and property tests indicated that ZSOME biodiesel had a high cetane index, good solubility, and a large flash point. Engine combustion experiment testified that burning the novel biodiesel has little influence on engine operation. Compared with 0# diesel fuel, the pressure lifting ratio reduced by 17–38.9% at 1500 rpm and by 4.6–10.2% at 2000 rpm for three different biodiesel blends, and the maximal instantaneous heat release rate lowered by 17.0–37.4% at 1500 rpm and by 5.0–11.3% at 2000 rpm for different blends. Granule emissions were decreased when the diesel engine burnt ZSO biodiesel under partial loads at 1500 rpm and 2000 rpm, NOX emissions were reduced at 1500 rpm but increased at 2000 rpm.

The Performance, Combustion, and Emission Characteristics of Neem Oil Methyl Ester and Its Diesel Blends in a Diesel Engine

In the present work, the biodiesel from non-edible neem oil (Azadirachta indica) is prepared by the method of two-step ‘acid-base’ process. An experimental investigation has been carried out to analyze the performance, emission, and combustion characteristics of a diesel engine fueled with neem oil methyl ester and its blends (10, 20, 30, 50, and 100%) vis-à-vis diesel at different loads and constant engine speed. The performance parameters evaluated include brake thermal efficiency; exhaust emissions, including CO, HC, NOx, and smoke intensity; and combustion parameters, including cylinder pressure and instantaneous heat release rate. Lower concentration of neem oil methyl ester in the blend gives better engine performance, combustion, and exhaust emissions. The experimental results proved that the use of neem oil methyl ester in diesel engines is a viable alternative to diesel.

Synthesis and Properties of a Novel Ethylene Glycol Monobutyl Ether Palm Oil Monoester Biofuel

Ethylene glycol monobutyl ether palm oil monoester (EGMEPM) was synthesized through transesterification with palm oil and Ethylene glycol monobutyl ether (EGME). Through L9(34) orthogonal experiments, optimum transesterification conditions were gained as: n(EGME):n(palm oil) = 10:1, w(metal sodium) = 1.2% total amount of alcohol at 70°C for 120 min. EGMEPM yielded 85.7%. The new biofuel had a high cetane number (77), good solubility, and a large flash point. Engine combustion experiment testified that burning the novel bioenergy has little influence on engine operation. Compared with 0# diesel fuel, the pressure lifting ratio reduced 2.9%–23.9% for B25 blends and 12.8%–38.9% for the novel bioenergy (B100), and the maximal instantaneous heat release rate lowered by 11.6%–33.3% for B25 and by 26.8%–42.7% for B100, respectively. When the diesel engine burnt B100 under partial loads at 1400 rpm, smoke, CO, HC, and NOX emissions were reduced.

Measurements of triggering and transient growth in a model lean-premixed gas turbine combustor

Instability triggering and transient growth of thermoacoustic oscillations were experimentally investigated in combination with linear/nonlinear flame transfer function (FTF) methodology in a model lean-premixed gas turbine combustor operated with CH 4 and air at atmospheric pressure. A fully premixed flame with 10 kW thermal power and an equivalence ratio of 0.60 was chosen for detailed characterization of the nonlinear transient behaviors. Flame transfer functions were experimentally determined by simultaneous measurements of inlet velocity fluctuations and heat release rate oscillations using a constant temperature anemometer and OH ∗/CH ∗ chemiluminescence emissions, respectively. The phase-resolved variation of the local flame structure at a limit cycle was measured by planar laser-induced fluorescence of OH. Simultaneous measurements of inlet velocity, OH ∗/CH ∗ emission, and acoustic pressure were performed to investigate the temporal evolution of the system from a stable to a limit cycle operation. This measurement allows us to describe an unsteady instability triggering event in terms of several distinct stages: (i) initiation of a small perturbation, (ii) exponential amplification, (iii) saturation, (iv) nonlinear evolution of the perturbations towards a new unstable periodic state, (v) quasi-steady low-amplitude periodic oscillation, and (vi) fully-developed high-amplitude limit cycle oscillation. Phase-plane portraits of instantaneous inlet velocity and heat release rate clearly show the presence of two different attractors. Depending on its initial position in phase space at infinitesimally small amplitude, the system evolves towards either a high-amplitude oscillatory state or a low-amplitude oscillatory state. This transient phenomenon was analyzed using frequency- and amplitude-dependent damping mechanisms, and compared to subcritical and supercritical bifurcation theories. The results presented in this paper experimentally demonstrate the hypothesis proposed by Preetham et al. based on analytical and computational solutions of the nonlinear G-equation [J. Propul. Power 24 (2008) 1390–1402]. Good quantitative agreement was obtained between measurements and predictions in terms of the conditions for the onset of triggering and the amplitude of triggered combustion instabilities.

Analysis of Combustion Characteristics and Influencing Factors of Space Dispersed Double-Wall-Jet Combustion System

Based on the ideas of wall-guiding-spray and spatial dispersion, A new type of diesel engine double-wall-jet combustion system is designed. The effect of speed, load and injection condition on the double-wall-jet combustion system is researched by testing, on the double-wall-jet combustion system, the combustion modes for whole working condition is analyzed, the comparison of combustion and performance between the original machine with the new one is carried out. The results showed that: Instantaneous heat release rate of double-wall-jet combustion system shows a single peak. As the speed increases, the corresponding crank angle of ignition retards, the peak outbreak pressure increases and then decreases, the peak instantaneous heat release rate, the peak average temperature, the peak cylinder pressure rise ratio, and the cumulative heat release per unit mass of working gas is reduced. As the load increases, the corresponding crank angles of peak cylinder pressure and gravity center of heat release rate are postponed. With the load increasing, the ignition crank angle corresponds early at low speed, and the ignition point does not change significantly with the load at high speed. The effect of the injector hole diameter/number on the cylinder pressure and instantaneous heat release rate curve is not significant at high speed and large loads, but at low speed and large loads is significant. Cylinder pressure of 6-Φ21 injector is higher than 5-Φ25, the instantaneous heat release rate of 6-Φ21 injector has a trend of a single peak, the instantaneous heat release rate of 5-Φ25 injector has a trend of a double peak and the focus of the heat release rate postponed. With the advancing of injection timing, the ignition crank angle and combustion phase advances, the peak cylinder pressure increases. Injection pressure has little effect on the combustion characteristics. By comparison with the original machine, while maintaining the power performance of the same circumstances, the cylinder pressure and NOx emissions of double-wall-jet engine are reduced in degree, fuel consumption rate is not almost changed, and the same plane rather, smoke intensity is improved at low speed, smoke intensity at high speed smoke high-speed only deteriorates of 0.2-0.3 BSU.

Impact of curvature on the kinematic response of small flames

The objective of the study is to investigate the impact of curvature on the kinematic response of an axisymmetric curved laminar premixed flame, utilizing a phenomenological relationship between the curvature and the laminar burning velocity. The reference and the perturbed flame shapes are obtained by numerically or analytically integrating the flame kinematics equations. The steady reference flame shape deviates gradually from that obtained without the curvature effect as the effect of curvature intensifies. By having its tip rounded off, the overall flame height under curvature becomes lower. Perturbed flame shapes with curvature show more attenuated undulation than those without curvature effect. Linear perturbation analysis is performed to determine the frequency-domain response of the instantaneous heat release rate to upstream flow perturbations. In the low frequency range, results are qualitatively similar to those obtained using those obtained using the model without curvature, but substantial differences in the phase shift are observed as the frequency of perturbation increases. Flames under weak curvature effects show behaviors similar to a first-order filter, whose cutoff frequency increases as the effect of curvature becomes stronger. Careful comparison reveals that the flame is mainly influenced by the modification of the burning velocity due to the curvature of the mean reference flame at the low frequency range while the influence of the time-varying perturbed burning velocity increases as the frequency of perturbation increases. A rule for scaling the response is proposed to match the results with and without the curvature effect, based on asymptotic analysis of the flame kinematics. Rescaling is effective for the low-frequency range, and a good correspondence between the results with and without the curvature effect is achieved.

Comparative Performance, Emission, and Combustion Characteristics of Rice-Bran Oil and Its Biodiesel in a Transportation Diesel Engine

The methyl esters of vegetable oils known as biodiesel are becoming increasingly popular because of their low environmental impact and potential as a green alternative fuel for diesel engines. Methyl ester of rice-bran oil (RBOME) is prepared through the process of transesterification. In the present investigation, experiments have been carried out to examine the performance, emission, and combustion characteristics of a direct-injection transportation diesel engine running with diesel, 20% blend of rice-bran oil (RBO), and 20% blend of RBOME with mineral diesel. A four-stroke, four-cylinder, direct-injection transportation diesel engine (MDI 3000) was instrumented for the measurement of the engine performance, emissions, in-cylinder pressure-crank angle history, rate of pressure rise, and other important combustion parameters such as instantaneous heat release rate, cumulative heat release rate, mass fraction burned, etc. A careful analysis of the performance, emissions, combustion, and heat release parameters has been carried out. HC, CO, and smoke emissions for RBO and RBOME blends were lower than mineral diesel while NOx emissions were almost similar and brake specific fuel consumption (BSFC) was slightly higher than mineral diesel. Combustion characteristics were quite similar for the three fuels.

Flame Spectra of a Turbulent Liquid-Fueled Swirl-Stabilized Lean-Direct Injection Combustor

Flame spectra within the UV/visible-light range are measured for a turbulent, liquid-fueled, swirl-stabilized, lean-direct injection combustor. The flame spectra are quite similar to those of lean premixed combustion, which can be attributed to the small droplet size and fast fuel/air mixing. Broadband background emissions around 431 nm, which mainly consist of CO * 2 chemiluminescence, are found to be self-similar with wavelength for both stable and unstable combustion. Chemiluminescence from OH * , CH * , and CO * 2 is found to be a nonlinear function of the airflow rate, the equivalence ratio, preheat temperature, and pressure. Procedures for the determination of the instantaneous heat release rate and equivalence ratios along the flame front are developed. For both combustion instability and forced flame responses, the prediction errors are within 2.0 % in the mean heat release rate, the mean air consumption rate, and the mean equivalence ratio. The assumption that chemiluminescence is proportional to the instantaneous heat releaser rate is generally invalid. Probably the proportionality is valid only in the weakly turbulent or wrinkled flamelet region in the absence of equivalence ratio variations and strong acoustic oscillations.

Direct Measurement of Heat Transfer Rates and Coefficients in Freezing Processes by the Use of Heat Flux Sensors

Heat exchange is often complex to assess in freezing equipment. Either the extensive calculation procedures based on product time-temperature data, or the lack of accurate thermophysical properties, or even the non-uniform processing conditions in industrial equipment, results in increased difficulty in calculating accurate heat exchange parameters. The present study aims to solve this kind of problem by introducing the use of heat flux sensors (or fluxmeters) for an online measurement of heat exchange parameters during freezing processes. Since food products often have irregular, moist and greasy surfaces, bad attachment of the sensors can lead to low accuracy in heat flux measurement. First, a technique was improved in this particular and a numerical procedure based on matching the experimental and simulated temperature histories was used to calibrate the sensors attached to Tylose R gels submitted to freezing and thawing cycles. Following this, the sensors were applied directly to a vegetable product undergoing freezing in a static freezer to measure the instantaneous product heat release rate and the local heat transfer coefficient. A fluxmeter-plastic transducer was also developed and used, coupled to an anemometer to map axially and transversally the local effective heat transfer coefficient and air speed profiles in a Super-Contact freezing tunnel. Results were compared with numerical simulations and showed good agreement. Irregular air speed distribution and low efficiency heat transfer zones were accurately detected, providing information for equipment optimization.

Software sensor based control of exothermic batch reactors

This study is essentially aimed at improving adaptive model predictive control of batch and semi-batch chemical reactor temperature. To this end, it involves a ‘software sensor’, able to estimate the rate of chemical heat production in a reliable and easy way, thanks to the use of an extended Kalman filter. Temperature measurements are used to determine the unknown parameters of on-line energy balance and kinetic equations. Thus, the instantaneous heat release rate is figured out and forecasted along the prediction horizon. The robustness and flexibility of the software sensor are examined on simulated reaction runs. The outcoming inferential controller is tested on a complex industrial protocol carried out in a pilot reactor. A comparison is made with the ‘basic’ digital regulator in the same working conditions.