Laboratory Heating Research Articles

Particle Conditioning for Improving Blockage Resistance of Denitration Catalysts in Sintering Flue Gas

The stability and safety of selective catalytic reduction (SCR) systems are threatened by potential catalyst blockages caused by fly ash deposition. This paper proposes to improve the blockage resistance of denitration catalysts for sintered fly ash through particle conditioning. X-ray fluorescence spectroscopy, scanning electron microscopy, and laser particle analyzer were combined with laboratory heating experiments and field tests for systematic research. The results indicate that the composition and morphology of sintered fly ash are intrinsic factors contributing to catalyst blockage, while heating conditions act as external triggers. The sintered fly ash primarily exhibits a fluffy, branched cotton-like structure. Its main components are K2O, Fe2O3, Na2O, and CaO, with the alkali metal oxides of potassium and sodium comprising 20% to 50%. At ambient temperature, sintered fly ash presents no agglomeration, but significant agglomeration occurs as temperature increases. Particle conditioning effectively inhibits the agglomeration tendency of sintered fly ash. Field tests show that catalyst activity remains unaffected even under severe blockage conditions. The pressure drop across the catalyst layers increases progressively, with the first layer displaying the least pressure drop and the third displaying the most. After particle conditioning, the pressure drop across the catalyst is stabilized at values below 600 Pa, effectively mitigating the blockage issue in the denitrification catalyst for sintering flue gas. This research provides critical technical support for the stable ultra-low emission of NOx from sintering flue gas.

Assessing whether a thermoluminescence peak at ∼100 °C in calcitic opercula can be used to monitor thermal reproducibility

The opercula of the gastropod Bithynia tentaculata is composed of calcite and exhibits three main thermoluminescence peaks at ∼100, 280 and 360 °C when heated at 0.5 °C.s−1. The two higher temperature peaks can be used for geological and archaeological dating, whilst the lower temperature peak has a lifetime of hours and is only seen after laboratory irradiation. This study explores whether this lower temperature TL peak can be used to assess the reproducibility of laboratory heating of opercula. As found in previous studies, the TL peak at ∼100 °C is seen to consist of at least two signals which have different lifetimes at room temperature. By fixing the interval between irradiation and measurement of the TL signal, the impact of these different lifetimes on the temperature at which the TL peak occurs (Tm) can be reduced, and replicate measurements on a single operculum using the same radiation dose yield values of Tm within 1 °C. Comparison of different opercula shows variation in Tm of 9 °C when heating at 5 °C.s−1, interpreted as primarily arising from variation in thermal lag between the hotplate and the different samples assessed. Reducing the heating rate to 0.5 °C.s−1 reduces the variation in Tm between opercula to 2 °C. Imaging the TL emission from opercula using an EMCCD shows spatial variation in heating, and also demonstrates the reduction in variability that can be achieved by using a slower heating rate. Thus, monitoring the position of the TL peak at ∼100 °C can be used to assess thermal reproducibility of TL measurements on calcitic opercula.

Long-term organic amendments increase the vulnerability of microbial respiration to environmental changes: Evidence from field and laboratory studies

Organic amendments can improve soil fertility and microbial diversity, making agroecosystems more resilient to stress. However, it is uncertain whether organic amendments will enhance the functional capacity of soil microbial communities, thereby mitigating fluctuations in microbial respiration caused by environmental changes. Here, we examined the impacts of long-term organic amendments on the dynamics of microbial catabolic capacity (characterized by enzyme activities and carbon source utilization) and microbial respiration, as well as their interrelationships during a period with fluctuating temperature and rainfall in the field. We then subjected the field soil samples to laboratory heating disturbances to further evaluate the importance of microbial catabolic capacity in explaining patterns of microbial respiration. In both field and laboratory experiments, organic amendments tended to increase the stability of microbial catabolic capacity, but significantly increased the vulnerability of microbial respiration to environmental changes. However, the direction and driving factors of microbial respiration affected by environmental changes differed between the field and laboratory experiments. Environmental changes in the field suppressed the promotional effects of organic amendments on microbial respiration mainly through reducing microbial catabolic capacity, while laboratory heating further enhanced microbial respiration mainly due to increased soil resource availability. Together, these findings suggest that increased microbial respiration variations under organic amendments may potentially increase the uncertainty in predicting soil carbon emissions in the scenario of ongoing climate/anthropogenic changes, and highlight the necessity of linking laboratory studies on environmental changes to field conditions.

Impact of Heat on Soil Water Repellency in Forest Soils from Different Depths using Water-Repellent Japanese Cedar (Cryptomeria japonica) Forest Soil

ome soils under plant species, such as casuarina, pine, eucalyptus, cedar, and cypress, show water- repellent conditions. Wildfires are common in forests dominated by these plant species as they produce highly flammable debris. The heat generated during wildfires alters soil characteristics, including soil water repellency (SWR). The responses of SWR to heat can differ depending on the heating temperature and the soil depth. This study aimed to examine the effects of different heating temperatures on SWR through a soil profile using Japanese cedar (Cryptomeria japonica) forest soil in Japan. Soil samples were collected from four different depths (0-5, 5-10, 10-15, 15-20 cm). Soils were exposed to heat with seven heating temperatures (TH) (50, 100, 150, 200, 250, 300, and 350° C) separately for 1 h using a programmable muffle furnace. The degree (contact angle) and the persistence of SWR in both heated and non-heated samples were measured using the molarity of an ethanol droplet test and the water drop penetration time (WDPT) test, respectively. In non-heated soils, the 0-5 cm layer showed the highest SWR (contact angle ~110°; WDPT≥3600 s). SWR decreased with depth to be non-repellent at 15-20 cm (contact angle≤90°; WDPT≤1 s). In heated samples, SWR of 0-5, 5-10, and 10-15 cm layers decreased with increasing TH, while the selection from 15-20 cm was non-repellent in all treatments. Soils of 0-5 cm depth showed extreme SWR (WDPT=≥3600 s) up to 200° C and became non-repellant at 250° C, while those of 5-10 cm showed extreme SWR up to 150° C, severe SWR (WDPT~1350 s) at 200° C, and became non- repellent at 250° C. The soils from 10-15 cm showed severe SWR (WDPT~2100 s) at TH of 50° C and became non-repellent at 100° C. Results revealed that upper soil layers with higher SWR required higher TH to become non-repellent, and soils from lower layers with lower SWR became non-repellent at lower TH. Further experiments are necessary to identify the changes in molecular levels of organic matter in response to the impacts of heat on SWR. 
 Keywords: Cryptomeria japonica, Laboratory heating, Soil water repellency, Wildfires

Biodegradability of unheated and laboratory heated dissolved organic matter.

Following wildfires, partially combusted biomass remains on the forest floor and erosion from the landscape can release dissolved pyrogenic organic matter (dPyOM) to surface waters. Therefore, post-fire alterations to dissolved organic matter (DOM) in aquatic systems may play a vital role in DOM stability and biogeochemical cycles. Dissolved PyOM biodegradation remains poorly understood and is expected to vary with combustion temperature and fuel source. In this study laboratory heating and leaching of forest floor materials (soil and litter) were used to compare the biodegradability of unheated, low (250 °C), and moderate (450 °C) temperature leachates. Inoculation experiments were performed with river microbes. Dissolved organic carbon (DOC) and nitrogen (DON), inorganic nitrogen, and DOM optical properties were monitored for 38 days. Inoculation experiments showed significantly greater DOC biodegradation of low and moderate temperature samples (64% and 71%, respectively) compared to unheated samples (32%). The greater DOC biodegradation may be explained by lower molecular weight DOM composition of heated leachates which was supported by higher initial E2/E3 ratios (absorbance at 250 nm/365 nm). Further, the observed decrease in the E2/E3 ratio after incubation suggests biodegradation of smaller compounds. This trend was greater for heated samples than unheated DOM. Specific ultraviolet absorbance increased after incubation, suggesting biodegradation of aliphatic compounds. Inoculated moderate temperature samples showed the greatest DON degradation (74%), followed by low temperature (58%) and unheated (51%) samples. Overall, results suggest that low and moderate temperature dPyOM was more biodegradable than unheated DOM, which may have implications for aquatic biogeochemical cycling, ecosystem function, and water quality in fire-impacted watersheds.

Differential environmental-induced heat stresses cause the structural and molecular changes in the spleen of Japanese flounder (Paralichthys olivaceus)

Japanese flounder (Paralichthys olivaceus) is a cold-water fish widely cultured in Northeast Asia. With global warming and increased breeding density, Japanese flounder aquaculture is threatened by heat stress. Therefore, understanding the molecular mechanisms underlying heat stress is important. This study applied two laboratory heat stress conditions, gradual temperature rise (GTR) and abrupt temperature rise (ATR) to imitate the stresses faced by Japanese flounder. The histological damage of spleen and the underlying molecular mechanisms were revealed. Histological observation showed that the size and number of melanoma macrophage centers (MMCs) changed under the applied heat stresses; however, inflammatory infiltration and erythrocytes specifically appeared only under the ATR stress. Transcriptome analysis identified 1073 and 985 differentially expressed genes (DEGs) in the GTR vs. the C and the ATR vs. the C groups, respectively. Functional enrichment analysis illustrated GTR and ATR stresses affected similar categories while simultaneously influencing diverse functions. The “Protein processing in endoplasmic reticulum (ER)” was the most enriched pathway in two kinds of heat stress. The “Apoptosis” pathway was GTR-specific while the“DNA replication” was ATR-specific. In addition, the comparison between GTR and ATR stresses in “Protein processing in ER” pathway were further described. The results illustrated both acute and chronic heat stress could increase misfolded proteins, disrupt the ER function, and cause histological damage. Misfolded proteins in the GTR group were removed by apoptosis, whereas those in the ATR group were cleared via DNA-related pathways. Protein-Protein Interaction (PPI) analysis identified 20 hub genes, eight of which were shared between the two groups (hsp90aa1.1, hspa5, hsp90b1, hsp90ab1, hspa9, hsp70, hspe1 and hspd1); three (hspa4b, fn1a and bmp4) were GTR-specific, whereas nine genes (chek1, pcna, aurkb, rpal, cdc6, rrm1, mcm5, pold1 and mcm3) were ATR-specific. The current study sheds light on the molecular mechanisms underlying the heat stress response in Japanese flounder.

Thermal resistance of steels with increased strength properties for pressure vessels of advanced VVER reactors of various designs

The paper considers the results of structural studies and mechanical tests after a long-term thermal exposure of laboratory heats of the metallurgically improved 15Kh2NMFA steel and steel with an increased content of nickel considered as materials for the pressure vessels of advanced VVER-type reactors of various designs. It has been shown that, both for the improved 15Kh2NMFA steel and the high-nickel steel, there are no signs of grain boundary embrittlement after an segregation provoking embrittlement heat treatment. This is explained by the extremely low grain boundary segregation of phosphorus in the initial state caused by a high degree of the structure dispersity as well as by rather a low content of impurities. Besides, no changes have been found in the yield strength value for the improved 15Kh2NMFA steel, which agrees with the structure investigation results. For the high-nickel steel, a tendency towards a minor yield strength decrease by 5 to 10% and a regular reduction of the critical brittleness temperature has been revealed. A decrease in the mechanical properties has been caused by a relatively low temperature of tempering for the high-nickel steel and, accordingly, by the potential occurrence of the structure recovery during long-term thermal exposure, as evidenced by the results of an X-ray diffraction analysis. Despite the structure recovery in the high-nickel steel under the long-term thermal exposure, the main strengthening carbide phases remain stable. Due to this, the yield strength value remains at a relatively high level that exceeds the values for the modern VVER-type vessel steels, even in the case of a thermal exposure much in excess of the expected operating conditions for advanced VVER reactors. The observed decrease of critical brittleness temperature during the long-term thermal exposure contributes to an increase in the steel resistance to brittle fracture.

A novel PZT-based high-power piezoelectric vibrator for ultrasonic motors: properties enhanced by Yb institution

PurposeThe electrical properties of piezoelectric vibrators have a crucial influence on the operating state of ultrasonic motors. In order to solve the problem that the current piezoelectric vibrator generates a large amount of heat during vibration to degrade its performance, which in turn affects the normal operation of ultrasonic motors, this paper prepares a novel piezoelectric vibrator and tests its maximum vibration velocity under the working condition, which is more than twice as much as that of the current commercial PZT-8.Design/methodology/approachThe crystal structures of the samples were analyzed by using an X-ray diffractometer. For microstructure observation, samples were observed by scanning electron microscope (SEM). The quasi-static piezoelectric coefficient meter (ZJ-3AN) was used for piezoelectric measurement. Dielectric properties were measured by utilizing an impedance analyzer (Agilent 4294A) with a laboratory heating unit. Ferroelectric hysteresis loops were obtained using a ferroelectric analyzer (Radiant, Multiferroic 100). A Doppler laser vibrometer (Polytec PSV-300F, Germany) and a power amplifier were used for piezoelectric vibration measurements, during which the temperature rise was determined by an infrared radiation thermometer (Victor 303, China).FindingsThe ceramics exhibit enhanced piezoelectric performance at 0.1–0.4 mol% of Yb doping contents. The ceramic of 0.4 mol% Yb reaches the maximal internal bias field and presents a larger mechanical quality factor of 1,692 compared with that of 0.2 mol% Yb-doped ceramic, in spite of a slightly decreased dielectric constant of 439 pC/N, the unit of the piezoelectric constant, which is the ratio of the local charge (pC) to the frontal force (N) and electromechanical coupling coefficient of 0.63. The vibrator with this large mechanical quality factor ceramic displays a vibration velocity of up to 0.81 m/s under the constraint of 20 °C temperature rising, which is much higher than commercial high-power piezoelectric ceramics PZT-8.Originality/valueThe enhanced high-power properties of the piezoelectric vibrator by Yb doping may provide a potential application for the high-performance USM and offer the possibility of long-term stable operation under high power for special equipment like USM. In the subsequent phase of research, the novel PZT-based high-power piezoelectric vibrator can be utilized in the USM, and the motor's performance will be evaluated under aerospace conditions to objectively assess the reliability of the piezoelectric vibrator.

Pyrotechnology and lipid biomarker variability in pine tar production

Tar or pitch produced from pine resin and wood played an important role in the past as an adhesive, waterproofing and medicinal product. However, the formation and biomolecular composition of pine tar produced only from resin under different combustion conditions (i.e., temperature and oxygen availability during heating) has not been as widely investigated as pine tar produced by dry distillation of wood or birch bark tar, for which an extensive literature is available. This lack of information hampers technological interpretations of biomolecular data obtained from organic residue analyses of archaeological pine tar products. In this study, we performed controlled laboratory heating sequences with pine resin (Pinus canariensis) at 150, 250, 350 and 450 ºC under both oxygenated and oxygen-limited conditions, and analyzed the products using gas chromatography-mass spectrometry (GC-MS). A control unheated resin sample was also analysed. We found that the formation of pine tar from resin occurs around 250–350 ºC under both oxygenated and oxygen-limited atmospheres. We also present and discuss the lipid biomarkers of pine resin and its combustion products according to changes in temperature and oxygen availability. Our reference data provide new information for the biomolecular identification of archaeological pine tar products and show potential for shedding light on the conditions in which tar was manufactured by ancient populations in different contexts.

Practical implementation of computationally-efficient machine learning-based control performance assessment system for a class of closed loop systems

This paper presents the concept of the computationally-efficient reduced order control performance assessment (RO-CPA) system for automatic detection of industrial single closed loop control systems whose performance could be not acceptable due to a poor tuning of the controller. The proposed machine learning (ML) based classification system is derived for a broad class of industrial control closed loops based on the proportional–integral–derivative (PID) controller. Apart from a high accuracy of the classification of the closed loop performance, the proposed RO-CPA system is derived to meet the requirements of low computational complexity and low memory usage. These requirements allow for practical implementation of RO-CPA in devices with low computational and memory resources, such as industrial programmable logic controllers (PLC) operating in manufacturing systems or embedded autonomous systems with dedicated PID-based control loops. This paper shows the rigorous ML-based design of the proposed RO-CPA system and the results of the validation of its classification accuracy. Additionally, an example of a practical implementation within a PLC in the form of a general purpose library function block is presented and the final experimental validation is made using a part of laboratory heat exchange and distribution setup.

Application of Machine Learning to Performance Assessment for a Class of PID-Based Control Systems

In this paper, a novel machine learning derived control performance assessment (CPA) classification system is proposed. It is dedicated for a wide class of PID-based control industrial loops with processes exhibiting dynamical properties close to second order plus delay time (SOPDT). The proposed concept is very general and easy to configure to distinguish between acceptable and poor closed loop performance. This approach allows for determining the best (but also robust and practically achievable) closed loop performance based on very popular and intuitive closed loop quality factors. Training set can be automatically derived off-line using a number of different, diverse control performance indices (CPIs) used as discriminative features of the assessed control system. The proposed extended set of CPIs is discussed with comprehensive performance assessment of different machine learning based classification methods and practical application of the suggested solution. As a result, a general-purpose CPA system is derived that can be immediately applied in practice without any preliminary or additional learning stage during normal closed loop operation. It is verified by practical application to assess the control system for a laboratory heat exchange and distribution setup.

The phenolic cured butyl rubber reclamation using different de-crosslinking agents

The cured rubber-made bladder used for curing the green tire because, it is thermally stable, and has low gas permeability. The bladder is made with the cured butyl rubber as a base rubber under a phenolic curing system. To save the resources and also, the environmental protection, it should be de-crosslink to gum rubber. A commercial source waste bladder rubber compounded with different de-crosslinking agents, including TMTD, DPDS, DCBS, MBTS, MBT, and TBBS. To do de-crosslinking, the prepared compounds were heated in a laboratory heating oven at different temperatures. The de-crosslinking parameters including the sol fraction and de-crosslinking percent measured using traditional rubber swollen tests. The Fourier transform infrared spectroscopy (FTIR) graphs showed the existence of the phenolic resin in the structure of waste bladder butyl rubber powder. Efficient de-crosslinking was observed for all studied de-crosslinking agents. It evidenced by the scanning electron microscope micrographs and also, the measured crosslink densities of the reclaimed rubbers. The highest and the lowest de-crosslinking percents belonged to the compounds with 4 phr DPDS in recipe at 220 [Formula: see text] and 4 phr DCBS at 180 [Formula: see text], respectively. Based on the obtained de-crosslinking parameters, the DPDS was selected as a suitable de-crosslinking agent for used waste rubber. In accordance with Horikx analysis, the oven heating broke down the crosslinks and rubber main chains simultaneously. Increasing the oven temperature had a positive effect on de-crosslinking process with similar effects on the crosslink and main chain break down.

Impact of temperature increase on the formation of magnetic minerals in shales. The example of Tournemire, France

Remagnetization is a pervasive mechanism affecting all kinds of rocks. Sedimentary rocks are particularly prone to such a mechanism because they can experience a wide range of physical and biogeochemical processes which can lead to partial or total loss of the original paleomagnetic record. Temperature increase is one of key factors affecting the rock magnetic properties in sedimentary rocks. Laboratory experiments on shales in the literature have shown that the magnetic mineralogy changed with temperature as low as 50 °C, and that new magnetic phase(s) are formed. The latter was identified to be mostly iron oxides (e.g., magnetite) and iron sulfides (e.g., pyrrhotite). In this study similar to what previously conducted on samples from the Paris Basin, a laboratory heating experiment is conducted on shale samples from the Tournemire tunnel (SE France) in a temperature range of 50 to 130 °C. This aims to simulate a new exposition of the samples to temperature and to identify the changes in magnetic phases, especially on FeIII-bearing minerals, with temperature. The remanence of the analyzed samples increases stepwise, suggesting an increasing concentration of magnetic minerals above their blocking volume with increasing temperature. Magnetite is the main magnetic carrier present and formed in the heated samples, with possibly pyrrhotite forming at high temperature. A conceptual model of magnetic mineralogy changes with temperature is presented and compared to previous results on claystones from the Paris Basin. The experimental observations support that the paleomagnetic record in sedimentary rocks affected by a later temperature increase during burial should be interpreted carefully. Indeed, remagnetization will likely occur when magnetic minerals record a secondary remanence either growing above their blocking volume or when exposed again to a temperature higher than the maximum burial temperature formerly experienced by the samples.

Experimental study on heating performance of micro-holes radiant plate under different installation types in severe cold regions

In order to alleviate energy shortage and maintain comfortable indoor environment, radiant air conditioning system is widely used. This paper designs and produces a miniaturized micro-holes radiant plate, which has the characteristics of orifice plate air supply and radiant heat transfer. The micro-holes radiant plate can be installation on the ceiling or sidewall without adding dynamics system and piping system. In order to explore the heating performance of the micro-holes radiant plate under different installation types, an experimental bench of air source heat pump micro-holes radiant plate heating system was built in Harbin, China, for laboratory heating. The experimental results showed that the indoor average temperature under various installation types could basically meet the set requirements, and the deviation was within 1 °C. The indoor horizontal temperature distribution was relatively uniform, and the temperature difference of each measuring point was less than 2 °C. The indoor vertical temperature difference was the smallest under the installation type with sidewall 50 mm from the ground at only 2.68 °C in the sitting position and 3.14 °C in the standing position, which meet China and ASHRAE standards. The ratio of the radiant heat transfer quantity under the sidewall heating was about 60 %, while the ratio under the ceiling heating was only about 30 %. The maximum ratio of the radiant heat transfer quantity was close to 70 % under the installation type with sidewall 50 mm from the ground. The experimental results provide theoretical support for the design and operation of air conditioning systems in severe cold regions.

Experimental study on heating performance of air source heat pump fresh air unit with fresh air and return air mixing in severe cold regions

In order to ensure the indoor air quality of the building, in view of the problem of fresh air heating in severe cold regions, this paper proposes an air source heat pump fresh air unit with fresh air and return air mixing. The mixing process of the fresh air and return air is realized in the mixing box, which increases the inlet air temperature of the condenser, creates a suitable condensation pressure, and ensures the energy-saving and stable operation of the unit. In order to explore the operation effect, heating performance and energy saving of the unit, an experimental bench was built in Harbin for laboratory heating. The experimental results showed that when the return air volume was 1400 m3/h, the fresh air unit could operate continuously and stably under the conditions of ensuring the fresh air volume of 700 m3/h and the supply air temperature of 24.0 °C. When the outdoor temperature was 4.9 °C, the heat pump COP was 4.29. Even when the outdoor temperature dropped to −20.9 °C, the heat pump COP still reached 2.46, while the COP of the fresh air system combining electric preheating, heat recovery and air source heat pump was only 1.44, and the COP of the fresh air system combining electric preheating, heat recovery and electric heat was only 1.21. In addition, the heat pump COP increased with the increase of the return air volume. As the set temperature increased, the heat pump COP increased first and then decreased.

Soil pH and Soluble Organic Matter Shifts Exerted by Heating Affect Microbial Response

Fire-induced alterations to soil pH and organic matter play an important role in the post-fire microbial response. However, the magnitude of which each parameter affects this response is still unclear. The main objective of this work was to determine the magnitude in which soil pH and organic matter fire-induced alterations condition the response of viable and cultivable micro-organisms using laboratory heating, mimicking a range of fire intensities. Four heating treatments were applied to unaltered forest soil: unheated, 300, 450, and 500 °C. In order to isolate the effect of nutrient or pH heating-induced changes, different culture media were prepared using soil:water extracts from the different heated soils, nutrient, and pH amendments. Each medium was inoculated with different dilutions of a microbial suspension from the same original, unaltered soil, and microbial abundance was estimated. Concurrently, freeze-dry aliquots from each soil:water extract were analyzed by pyrolysis-gas chromatography/mass spectrometry. The microbial abundance in media prepared with heated soil was lower than that in media prepared with unheated soil. Nutrient addition and pH compensation appear to promote microbial proliferation in unaltered and low-intensity heated treatments, but not in those heated at the highest temperatures. Soil organic matter characterization showed a reduction in the number of organic compounds in soil-heated treatments and a marked increase in aromatic compounds, which could be related to the observed low microbial proliferation.

Analysis of a Costly Fiberglass-Polyester Air Filter Fire

In September 2020, a fire at a liquefied natural gas (LNG) plant in the Arctic areas of Norway received national attention. In an unengaged air intake, the heat exchanger designed to prevent ice damage during production mode, was supplied hot oil at 260 °C. In sunny weather, calm conditions, and 14 °C ambient temperature, overheating of the unengaged air intake filters (85% glass fiber and 15% polyester) was identified as a possible cause of ignition. Laboratory heating tests showed that the filter materials could, due to the rigid glass fibers carrying the polymers, glow like smoldering materials. Thus, self-heating as observed for cellulose-based materials was a possible ignition mechanism. Small-scale testing (10 cm × 10 cm and 8 cm stacked height) revealed that used filters with collected biomass, i.e., mainly pterygota, tended to self-heat at 20 °C lower temperatures than virgin filters. Used filter cassettes (60 cm by 60 cm and 50 cm bag depth) caused significant self-heating at 150 °C. At 160 °C, the self-heating took several hours before increased smoke production and sudden transition to flaming combustion. Since the engaged heat exchanger on a calm sunny day of ambient temperature 14 °C would result in temperatures in excess of 160 °C in an unengaged air intake, self-heating and transition to flaming combustion was identified as the most likely cause of the fire. Flames from the burning polymer filters resulted in heat exchanger collapse and subsequent hot oil release, significantly increasing the intensity and duration of the fire. Due to firewater damages, the plant was out of operation for more than 1.5 years. Better sharing of lessons learned may help prevent similar incidents in the future.

Laboratory study of a hydronic concrete deck heated externally in a controlled sub-freezing environment

Geothermal heating of bridge decks is a reliable and sustainable method for bridge de-icing that has been increasing in demand since conventional de-icing methods were proved to be environmentally hazardous. Previous research on geothermal heating of bridge decks relied on hydronic pipes embedded inside of bridge decks, which are confined to newly constructed bridges. For existing bridges, a newly devised method for external heating has been recently tested under limited laboratory conditions to determine its overall performance. This study explores laboratory heating tests of a concrete slab with a thickness representing a typical concrete bridge deck. This slab was equipped with a simulated geothermal bridge de-icing system and tested inside a freezer subjected to sub-freezing controlled conditions. Various winter scenarios were applied to the system to determine its heating performance and how feasible it will be for the system to be transferred to the field. A prediction equation was developed to estimate the total energy reserves required to permit de-icing, and statistical analysis was performed and validated with test results. The slab surface heat flux was estimated to range from 27 W/m2K to 73 W/m2K from the heating test. The externally-heated deck can be designed with the developed prediction equation for snow melting.

Application of the Grain-Based Rock-Eval Pyrolysis Method to Evaluate Hydrocarbon Generation, Expulsion, and Retention of Lacustrine Shale

The study on hydrocarbon generation, expulsion, and retention of shale is becoming more and more important as the exploration of unconventional oil and gas worldwide. There are multiple sets of lacustrine shales in the eastern area of China, which show a great potential for shale oil/gas exploration. In this study, a grain-based Rock-Eval pyrolysis method was conducted on three sets of lacustrine shales, including the Nenjiang shale, Shahejie shale, and Maoming oil shale, to evaluate the hydrocarbon generation, expulsion, and retention. For comparison, pyrolysis of kerogen from the three shale samples was also carried out under the same experimental conditions. The Maoming oil shale showed a slightly broader distribution of activation energies than the Nenjiang and Shahejie shales, while the Nenjiang shale showed higher dominant activation energy than the Shahejie shale and the Maoming oil shale. At laboratory heating rates (5–25°C/min), the corresponding temperature to the maximum hydrocarbon generating rate of shale grains was collectively higher than that of their kerogen, especially for the Nenjiang and Shahejie shales, which implies a lagging effect during the hydrocarbon generation and expulsion process for the shales. By calculating the differences in hydrocarbon yields between shale grain and kerogen samples, the content and proportion of the retained hydrocarbons were measured at different maturation stages. The results showed that the Nenjiang shale from the Songliao Basin has the strongest retention ability but the weakest expulsion ability, whereas the Shahejie shale from the Dongying Depression has the strongest expulsion ability but the weakest retention ability among the three samples. Moreover, it is found that the pore structure of lacustrine shales is likely the principal factor controlling the hydrocarbon retention ability/capacity. This study is expected to provide a geochemical quantitative basis for evaluating hydrocarbon generation, expulsion, and retention of shale.

Influence of Low and Extreme Heat Fluxes on Thermal Degradation of Carbon Fibre-reinforced Polymers

This study considers the influence of different irradiation scenarios on the thermal degradation of carbon fibre-reinforced polymers (CFRP). Real threats are simulated, such as fires with long-lasting low heat fluxes and nuclear heat flashes with short-lasting high heat fluxes. For this purpose, coated and uncoated quasi-isotropic samples of the commercially available CFRP HexPly® 8552/IM7 are thermally irradiated from one side by an electrical heater of a cone calorimeter and a xenon short-arc lamp of a laboratory heat flash simulator with heat fluxes between 5 and 175 W/cm2 at varying time intervals. The specimens’ temperature is recorded on the front and back side as well as at different laminate depths. The CFRP are analyzed with ultrasonic testing (UT), infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM) and micro-focused computed X-Ray tomography (μCT). Destructive tests are performed to determine the mechanical properties in terms of interlaminar shear, compressive and tensile strength. When samples of CFRP are exposed to higher heat flux, high temperatures and temperature gradient values occur along the cross-section. As a result, extreme damage gradients appear in the material, leading to changes in damage behavior and loss of mechanical properties within seconds. However, to ensure the safety of the material in case of thermal exposure, loading limits are introduced, indicating the threshold for strength collapse. In addition, with the application of coatings, thermal degradation of CFRP can be delayed. Finally, the time-heat flux superposition principle is established to predict the residual strength under different loading scenarios.