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Carbonate rocks are one of major geothermal reservoir types around the world. Understanding the thermal properties of carbonate rocks is of significance to the assessment and utilization of deep geothermal reservoirs. Different from conventional test methods, this paper introduced a new approach, molecular dynamics calculation (MDC), to studying the thermal properties of carbonate rocks. By means of MDC, the thermal properties including specific heat, thermal conductivity and thermal diffusivity of four types of carbonate rocks including calcite, dolomite, magnesite, and smithsonite were investigated. The intrinsic relationship among the Debye temperature, elastic and thermal properties of carbonate rocks was revealed. The variations of the thermal properties with the average atom weight and temperature (300–800K) were obtained and regressed as functional formulas for applications. Further, taking carbonate rock samples from North China as an example, the specific heat and thermal conductivity were tested and compared with the MDC results based on actual lattice parameters by using X-ray diffraction method (XRD). The results showed that there was a good agreement between the test and calculation results. Finally, the thermal properties of ferroan dolomite samples were predicted. The present method can provide a promising extension tool for analyzing other crystalline rocks for geothermal applications. [ABSTRACT FROM AUTHOR]

The use of bio-based building materials is a sustainable opportunity to reduce the environmental footprint associated with the construction sector. The achievement of this objective is primely achieved through the valorisation of vegetable waste, resulting in a reduction in the use of primary source material and waste generation. Within the scope of this study, the focus is directed towards research concerning the thermal, acoustic, and fire behaviour properties of bio-based building materials. This study conducts a comprehensive bibliometric analysis encompassing all documents meeting these criteria within the Scopus database, spanning two decades, from 2003 to 2023. The comprehensive analysis covered a total of 1081 documents, which were analysed. This analysis furnishes insight into various facets, including the temporal evolution of publications, journals boasting the highest publication counts and impact, influential research areas, countries with substantial contributions and their collaborative patterns, noteworthy affiliations, prolific authors, and seminal documents, alongside recurrent keywords. The objective of this comprehensive study is to provide a detailed analysis of the documents published up to the present day, in order to identify research gaps and potential opportunities in this field, to assist new researchers interested in the subject. The analysis reveals that bio-based building materials have gained substantial attention over the past decade. With each passing year, the published documents have increased their impact and become more specific, underscoring the growing importance of this subject. This evolution has also fostered a broader network of researchers engaged in this field. However, it is noteworthy that the characterization of these materials focuses predominantly on their thermal properties, while research avenues related to acoustic and fire properties remain less explored and present opportunities for future investigation. • This study contributes to identify research gaps and potential opportunities in the field of bio-based building materials. • Studies in bio-based building materials have shown an annual growth of the 25% since 2014, being a topic on the rise. • France and China are the countries with the highest scientific publication on bio-based building materials. • Keywords play a crucial role in making visible the research within bio-based building materials. • "Thermal Conductivity" and "Thermal insulation" are the most repeated keywords in this field. [ABSTRACT FROM AUTHOR]

At present, the yield of common buckwheat, which is mainly grown in northern Shaanxi of China, is low and the grain quality is poor. Nitrogen is an important nutrient for the growth of common buckwheat, and appropriate nitrogen application can improve the grain quality. Nitrogen fertilizer could alter the starch granule morphology shapes and the granule size distribution. With increasing nitrogen levels, branch number, flower clusters number, grain number per plant, contents of protein and fat, size distribution of "C" granules, and percentages of light transmittance significantly increased, whereas amylose content and retrogradation decreased. All the samples displayed typical A-type X-ray diffraction patterns. Starch showed higher pasting temperature and gelatinization enthalpy but lower trough and final viscosities under high nitrogen levels. These results suggested N 2 treatment was more suitable for common buckwheat growth, principal components and correlation analysis revealed that nitrogen fertilizer significantly affected the physicochemical properties of common buckwheat starches. [ABSTRACT FROM AUTHOR]

Nelumbo nucifera Gaertn., Eleocharis dulcis , Sagittaria sagittifolia L., and Trapa bispinosa Roxb. are common aquatic vegetables that are rich in starch. Starches from these four aquatic vegetables and their applications in edible films were studied to facilitate full use of starch resources. Significant differences in transparency, freeze–thaw stability, water solubility index, swelling power, water and oil absorption capacities, starch particle morphology, and rheology were observed among the starches from these four aquatic vegetables. All starches exhibited a typical "A" type diffraction pattern. N. nucifera , E. dulcis , and S. sagittifolia starches have similar thermal properties, while T. bispinosa starch has a higher gelatinization temperature. S. sagittifolia starch film has the highest transparency and lower WVP and water solubility. These results will promote the development of products based on starch obtained from aquatic vegetables. [ABSTRACT FROM AUTHOR]

• Variation of atomic ratio and microcrystalline structure with temperature under nitrogen atmosphere were explored. • Abrupts of H/C and O/C occured as rising the temperature of coal samples. • Correlation was established by thermal property with atomic ratio and microcrystalline structure. To explore the main influencing factors of atomic ratio (O/C, N/C, and H/C) as well as microcrystalline structure (d 002 , L a , L c , and M c) on thermal properties (specific heat capacity, thermal conductivity, and thermal diffusivity) at certain temperatures within 30.0–300.0 °C, three coal samples were collected from coal mines of Dafosi, Yangjiaping, and Hujiahe in Binchang coalfield, Shaanxi Province, PR China. Thermal properties of coal samples were determined by laser-flash apparatus in nitrogen atmosphere. After temperature treated at 30.0, 60.0, 90.0, ..., 300.0 °C in nitrogen atmosphere, the atomic ratio and microcrystalline structure of samples were measured by proximate analyser and X-ray diffractometer. The results indicated that with an increment in the temperature, the value of H/C for three coal samples diminished slightly and then promptly, whereas O/C diminished slightly and then increased before 120.0 °C, as well as finally increasing, and the N/C had no obvious change. Concurrently, the microcrystalline structure of coal samples became more orderly and complete. Furthermore, the TD decreased with temperature, the SHC and TC showed an opposite trend with TD. Based upon grey correlation analysis, the major influencing factors of atomic ratio and microcrystalline structure on thermal property were approached. The results provided insight into the physicochemical properties of the coal of interest for predicting the progress of coal spontaneous combustion. [ABSTRACT FROM AUTHOR]

Common buckwheat starch (CBS) has extensive using value in the human diet. In this study, the molecular structure and physicochemical properties of CBS isolated from five cultivars collected from three regions of China were studied. Variations in molecular structure, crystalline structure, complexity, water solubility (WS), swelling power (SP), pasting properties, and thermal characteristics were recorded among the starches. The CBS had both similarities and differences in its properties by comparison with maize starch (MS) and potato starch (PS). The average molecular weight (M W) and amylopectin average chain length (ACL) of CBS ranged from 3.86 × 107 g/mol to 4.68 × 107 g/mol and from 21.29% to 22.68%, respectively. CBS and MS were divided into one subgroup and showed typical A diffraction patterns, while PS was divided into two subgroups and exhibited a typical B polymorphic pattern. The WS and SP of all the starches significantly increased with increasing temperature and had great variation at 70 °C and 90 °C. Pearson's correlation analysis showed that the molecular structure of starches greatly affected the physicochemical properties. This study revealed that the physicochemical properties of CBS could be affected by the molecular structures. • Common buckwheat and maize starches showed typical A diffraction patterns. • Structural complexity of five common buckwheat cultivars were similar. [ABSTRACT FROM AUTHOR]

A geological stratum is a rock or soil layer that has internally consistent characteristics and is distinguishable from adjacent layers. A stratigraphic section contains reference information for the strata of an associated sedimentary area. In this paper, the thermal properties of 36 rock formations in a succession of the Yangtze plate in China are studied. Thermal properties are analyzed with an emphasis on rock formations, rock lithological types and dry/saturated conditions. The results show that thermal conductivity varies dramatically with different rock lithological types, which range from 0.72 W m−1 K−1 to 4.49 W m−1 K−1. The analysis of biochemical sedimentary rocks shows that silicate has the highest thermal conductivity, followed by dolomite and limestone; this variation is due to the differences in rock-forming minerals. The thermal conductivity of the clastic rocks is mainly determined by the type of minerals, the porosity and the water content. Compared to dry samples, the thermal conductivity and volumetric heat capacity of saturated samples are higher. Moreover, the thermal conductivity data of nine other locations in the Yangtze plate are compared with the stratigraphic data. This analysis shows that thermal conductivity matches very well for most of the geological formations, with the exception of sandstone, which exhibits a significant deviation across formations. Finally, the thermal properties for the Yangtze plate are mapped for insight on their spatial distribution. • Thermal properties of 36 rock formations in a sedimentary succession are measured. • Thermal conductivity varies dramatically with lithological types of rocks. • Two categories rocks are studied with emphasis on sedimentogenesis. • Thermal properties of Yangtze plate are mapped for insights on spatial distribution. [ABSTRACT FROM AUTHOR]

Windmill palm, a tree species that is native to China, has gained attention with regard to the production of substantial amounts of biomass fibers via yearly pruning. This study investigates the structure and thermal properties of cellulose nanofibrils (CNFs) obtained from windmill palm biomass, with the goal of promoting the usage of these CNFs. Alkali–ultrasound treatments are employed herein to prepare samples of the CNFs. The micromorphology of the prepared samples is observed using scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. Furthermore, X-ray diffraction analysis is used to examine the aggregated structure of the samples, and thermogravimetric analysis is used to investigate their thermal properties. Results indicate that during alkali hydrolysis when obtaining CNFs, the fiber cell wall exhibits distinct spiral cracking. The diameter of the obtained nanocellulose is <90 nm. The removal of lignin and hemicellulose materials from the fiber cell enhances the crystallinity of CNFs to as high as 60 %, surpassing that of windmill palm single fibers. The thermal decomposition temperatures of the CNFs are found to be 469 °C and 246 °C for the crystalline and amorphous regions, respectively. [ABSTRACT FROM AUTHOR]

• Building energy conservation is very important in today's society. • A bio-insulation material using wheat straw as aggregate is made by experiment. • The binder adopted in this material is geopolymer with H 2 O 2 as foaming agent. • The thermal conductivity varies from 0.092 to 0.18623 W m−1 K−1. • The compressive strength varies from 0.18 to 5.622 MPa. During the process of China's rural urbanization and agricultural supply-side reform, the disposal of a large number of agricultural and forestry wastes will be a big problem. This study deals with effect of four variables on the thermal, mechanical, hydraulic properties and microscopic morphology of the bio-insulation materials using wheat straw as aggregate and geopolymer as binder. The four variables are wheat straw length dimension (L), prewetting water /wheat straw mass ratio1 (Wp/W), wheat straw/solid content of binder mass ratio (W/S) and H 2 O 2 /solid content of binder mass ratio (H/S), respectively. The results show that all the four variables have a great influence on the foaming process and skeleton structure of the geopolymer, which greatly affect the properties of the bio-insulation materials. In conclusion, the thermal conductivity of bio-insulation materials varies from 0.092 to 0.186 W m−1 K−1, and the compressive strength varies from 0.18 to 5.622 MPa with the density being 235–894.1 kg m−3. Moreover, the values of water and moisture absorption rates are 32–107% and 4–33% respectively. A desirable bio-insulation material with wheat straw length of 0.2 cm, Wp/W being 1, W/S being 0.124, and H/S being 0.0124, is recommended, of which the thermal conductivity is 0.101 W m−1 K−1 with the compressive strength being 1.2 MPa and the density being 302.4 kg m−3. This new kind of bio-insulation material exhibits good thermal and mechanical performances, which allows it to be applied as a thermal insulation material in buildings, especially the prefabricated buildings. And it is beneficial to energy saving and environmental protection. [ABSTRACT FROM AUTHOR]

This study was to compare the characteristics of 21 starches isolated from chestnuts produced in different regions in China, also to investigate their potential food applications. Starches were isolated from chestnuts under the Castanea mollisima Blume variety with sub-varieties of Banli, Youli, and Maoli. Several properties of the starch samples were examined, including the moisture content, amylose content, morphological characteristics, color values, light transmittance, syneresis, swelling power, water solubility index, pasting properties, FTIR characteristics, X-ray diffraction (XRD) patterns, and thermal properties. The results showed that starches isolated from Youli presented higher resistance to shear and swelling during heating, indicating more suitability for high-heat cooking. The FTIR spectra confirmed the polysaccharide nature of all the chestnut starches. The XRD patterns showed most chestnut starches were in C b -type, while only five were in C a -type. Overall, this comparative study would be relevant for the further exploration of the potential utilization of chestnut starch in both food and non-food industries. • Physiochemical properties of 21 chestnuts starches were examined. • Starches presented significant differences in morphology, pasting, and thermal properties. • Starches from Maoli had generally smaller granule sizes. • Starches from Youli presented higher resistance to shear and thermal swelling. • All chestnuts had C-type starch, among which most starches were in C b -type. [ABSTRACT FROM AUTHOR]

• A PVT collector with a roll-bond absorber is designed for rural home application. • Thermo-laminating is a novel and convenient method for PV-absorber connection. • The validated PVT model can simulate the roll-bond PVT performance accurately. • The model is available for predicting the dynamic performance of PVT systems. This paper mainly investigated the performance of a low-cost roll-bond water-type photovoltaic thermal (PVT) collector from both experimental and modelling approaches under the climatic conditions of Sichuan Basin of China. The design and manufacturing process of the PVT prototype adopted the available commercial PV panels for convenience and for reducing the manufacturing cost. The experiment measured all the main properties of the developed PVT module. The excellent heat transfer performance of its roll-bond absorber plate was also validated by outdoor steady-state tests. Then, the steady-state numerical models were used to simulate the performance of the PVT prototype in TRNSYS. By comparing the simulation and experimental results, two robust models were selected which have their own advantages in charactering the thermal and electrical properties of the PVT collector. Through validating the numerical models with experimental data, the deviation between the simulated and the measured values was further reduced. In addition, a complete photovoltaic thermal–domestic hot water (PVT-DHW) system with such PVT collectors was developed in TRNSYS, by which the annual system output and efficiency were predicted and analysed. [ABSTRACT FROM AUTHOR]

The Local Climate Zone (LCZ) scheme aims to provide an objective and standardized classification protocol for urban temperature studies in any city. The field observed temperature data from 12 selected LCZ sites in Nanjing, China, for the period from July to November 2016, was used to evaluate the LCZ scheme. The results here are the first to assess the LCZ scheme in a high-density city in mainland China. Distinct thermal differences among the LCZ sites provide preliminary evidence to support that the LCZ concept is applicable for urban temperature studies in cities of China. [ABSTRACT FROM AUTHOR]

Thermal properties of glazing facades and windows system may affect the solar heat gain through its heat transfer area to an enclosed built environment, eventually affects the electricity consumption of air-conditioning system. Advanced glazing technologies offer a lower solar heat gain. This research project examines the relationship between the types of glazing, orientation and window-to-wall ratio (WWR) against the solar heat gain through the fenestration and annual electricity end uses for a window-typed air-conditioning system, by means of building energy simulation software, EnergyPlus. Reduction of electricity end uses and windows heat addition for the same windows configuration with different advanced glazing ranges are 13.8% and 69.1% respectively, in Hong Kong. The relationship among different construction configuration and climate is investigated. The optimum choice of glazing for minimizing the heat gain and maximizing the visual transmissibility is also suggested in accordance to the simulation results. [ABSTRACT FROM AUTHOR]

Super-long urban road tunnels have become prevalent in China recently. This study established a three-dimension CFD model containing two adjacent super-long urban road tunnels to estimate characteristics of pollution dispersion outside the tunnels. The results indicated that crossflow between two adjacent tunnels was quite severe, which contributed to carbon monoxide concentration was almost 50 ppm exceeding the 10 ppm limit of National Standard in China for 1h exposure level when exhaust shafts were absent. When the shafts exhausted 80% pollutants from the tunnel portal, crossflow between two adjacent tunnels could at least decrease to 20% of the conditions without shafts. The simulation results could not only demonstrate the importance of shafts for super-long urban road tunnels, but also provide a fundamental and guideline for evaluation of urban environment and design of the tunnel exhaust shafts, including locations and types. [ABSTRACT FROM AUTHOR]

Yam (Dioscorea spp.) is a major food source in many countries due to its tuber rich in starch (60 %–89 % of the dry weight) and various important micronutrients. Orientation Supergene Cultivation (OSC) pattern is a simple and efficient cultivation mode developed in China in recent years. However, little is known about its effect on yam tuber starch. In this study, the starchy tuber yield, starch structure and physicochemical properties were compared and analyzed in detail between OSC and Traditional Vertical Cultivation (TVC) with Dioscorea persimilis "zhugaoshu", a widely cultivated variety. The results proved that OSC significantly increased tuber yield (23.76 %–31.86 %) and commodity quality (more smooth skin) compared with TVC in three consecutive years of field experiments. Moreover, OSC increased amylopectin content, resistant starch content, granule average diameter and average degree of crystallinity by 2.7 %, 5.8 %, 14.7 % and 9.5 %, respectively, while OSC decreased starch molecular weight (Mw). These traits resulted in starch with lower thermal properties (To, Tp, Tc, ΔH gel), but higher pasting properties (PV, TV). Our results indicated that cultivation pattern affected the yam production and starch physicochemical properties. It would not only provide a practical basis for OSC promotion, but also provide valuable information on how to guide the yam starch end use in food and non-food industries. [ABSTRACT FROM AUTHOR]

In this work, Huadian oil shale from China was treated by hydrothermal pretreatment at 200 °C with 1.0–2.5 h in order to investigate the effect of hydrothermal pretreatment on pyrolysis product distribution and characteristics of oil. The differences in the elemental composition and thermal behavior between the untreated and treated oil shale were analyzed and compared. The hydrothermal treatment process could decompose oxygen functional groups and remove some water soluble inorganics in oil shale, which decreased the formation of gas and water during the pyrolysis. However, hydrothermal pretreatment was conducive to increasing shale oil yield. The maximum of oil yield was obtained at the pretreatment time of 2.0 h. The enhancement of the free-radical reactions during the pyrolysis and the reduction of the secondary cracking reactions of the generated oil vapors were considered as the main reasons. The oil obtained by the treated oil shale had a higher H/C ratio, indicating it had high energy content. The analysis results of chemical compositions in oils showed that the relative content of aliphatic hydrocarbons significantly increased after hydrothermal pretreatment. The further analysis demonstrated that the increase in the pretreatment time caused the generated long chain hydrocarbons tended to be directly released from oil shale particles, and were condensed into the oil. [ABSTRACT FROM AUTHOR]

• Large-sized InSe single crystal. • The ground simulation apparatus of China space station. • γ-Phase with space group of standard R 3 m. • A positive thermal expansion at 30–500 °C. • No element volatilization even the temperature as high as 1000 °C. Indium selenide (InSe) semiconductor crystal was grown by using the ground simulation apparatus of China space station in this work. The furnace was controlled at 715 °C and the temperature gradient for crystal growth was ∼30 °C/cm. The as-grown InSe crystalizes in γ-phase with space group of R 3 m. The average etching pits density (EPD) is estimated to be about 104/cm2. Thermal analysis indicates a positive thermal expansion at 30–500 °C and no volatilization occurred even as high as 1000 °C. This work not only establishes a reliable process for preparing large-sized InSe single crystal but also creates a foundation for further work in outer space in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] • LT + LL (low temperature and low light) reduced thermal stability in the cultivars. • Poor-quality cultivar deteriorated starch physicochemical properties under LT + LL. • Good-quality rice cultivar improved starch pasting properties under LT + LL. • Poor-quality cultivar decreased compactness of starch in grains under LT + LL. Late-season indica rice frequently encounters low temperature (LT) along with low light (LL) after heading in southern China, which deteriorates the grain quality by altering starch quality. However, the detailed effects on starch properties of these stressors remain unclear. Herein, two indica rice cultivars with good and poor grain quality were grown under control (CK), LT, and LT + LL conditions after heading and the structural and physicochemical properties of their starch were evaluated. Compared with CK, LT and LT + LL worsened thermal and pasting properties of starch in the two cultivars, mainly because they increased branch chain branching and A chain (DP ≤12), and decreased average branch chain length and crystallinity. Compared with LT, LT + LL deteriorated the pasting properties of the poor-quality cultivar, such as reducing breakdown (BD), final and peak viscosity, which mainly owing to decreasing the starch branching and crystallinity degrees, and increasing the small starch granules (d < 10 μm). Gelatinization enthalpy and BD both had significant and positive correlations with amylose content, the ratio of amylose and amylopectin, B3 chain and crystallinity. Taken together, these results suggest that LT and LT + LL during grain filling can deteriorate the physicochemical properties of starch in late-season indica rice cultivars by disrupting starch multilevel structure, especially upon LT + LL. In particular, while poor-quality cultivar had poorer physicochemical properties, the good-quality cultivar had poorer thermal properties under LT + LL. [ABSTRACT FROM AUTHOR]

With the increase of coal energy mining depth in China, coal spontaneous combustion phenomenon becomes more frequent, which makes the safe mining of coal energy in China under serious threat. In order to prevent coal spontaneous combustion, it is significant to investigate the process of coal oxidation and spontaneous combustion by combining thermal and microstructural properties, which is a necessary study to figure out the mechanism of coal spontaneous combustion. A series of coal oxidation experiments were conducted with the aid of high precision Calorimeter and X-ray diffractometer. The results show that the thermal properties of coal spontaneous combustion have obvious segmentation characteristics which is not affected by the degree of metamorphism and heating rates, and the initial exothermic temperature is positively correlated with heating rates. The effect of temperature on microscopic characteristics is not uniform, but the degree of metamorphism has a regular change for microscopic characteristics. Although temperature does not play a decisive role, the spatial structure of coal oxidation process has some reversibility with the change of temperature. Besides, thermal dynamic balance is an important cause of microstructure changes. It is expected that this work will contribute to the refinement of the theory of coal spontaneous combustion. [Display omitted] • The thermal properties have obvious segmentation characteristics. • The initial exothermic temperature is positively correlated with heating rates. • The thermal dynamic balance is an important cause of microstructure changes. [ABSTRACT FROM AUTHOR]

• Neural network regression analysis is performed when studying red mud-AAC with different w/s ratios. • Relationship between pore structures and performances of red mud-based AAC is clarified. • A model reflecting pore structures and compressive strength of AAC is proposed with better regression and applicability. • A modified series–parallel model of thermal conductivity is provided in red mud-based AAC. • Neural network regression analysis could be effective based on a mass of measured data. A large amount of red mud needs to be disposed of in China, which causes environmental pollution. The feasibility of using red mud in autoclaved aerated concrete (AAC) has been confirmed, and its strength and thermal properties are highly related to its pore structures. To further clarify the relationship between the pore diameter (shape) and performances of red mud-based AAC, this study aims to establish a quantitative relationship between the compressive strength and the pore structure of AAC with red mud as well as its average shape factor of pores with a diameter above 0.5 mm, which was relied on the principle of elasticity. The experimental results show the strength formula of red mud-based AAC considering its porosity and its pore shape is R = R 0 0.03 1 - 1.21 V p 2 3 + 0.95 S H π 2 - 4 π + 8 + S H 2 π 4 + 16 S H π 2 - 8 S H π 3 16 + S H π 2 - 4 π + 8 + S H 2 π 4 + 16 S H π 2 - 8 S H π 3 . At the same time, to explore the constitutive relationship between the pore structure and thermal properties of red mud-based AAC, the series–parallel model of thermal conductivity is analyzed and modified, indicating that the series model has greater contribution to the effective thermal conductivity of AAC, where the expression is λ eff = 0.9 1 v 1 / λ 1 + v 2 / λ 2 + 0.19 (v 1 λ 1 + v 2 λ 2). Finally, through the neural network regression analysis, it is proved that the established model reveals good accuracy. [ABSTRACT FROM AUTHOR]

Although temperature is considered a key factor influencing rock decay, little is known about the quantitative relationship between a rock's decay rate and temperature, which makes it difficult to quantitatively predict the rate of rock decay under varied temperature during wetting–drying cycle conditions. Thus, the aim of the present paper was to observe the decay rate of various purple mudstones and to develop a model with which to calculate their decay rates under varied temperature conditions. Three types of purple mudstone were sampled from the Tuodian group (J 3 t), Matoushan group (K 2 m) and Lufeng group (J 1 l), located in the Chuxiong district of Yunnan province, south-western China. All samples were manually cut into cubes of 50 × 50 × 50 mm, before being subjected to 39 wetting–drying cycles in a 2 mm sieve under artificial constant temperature, natural daily temperature variation and artificial temperature alternation (minimum and maximum) treatments in the laboratory. Decay rates were calculated by weighing the mass remaining in the sieve after each treatment cycle. The results showed that the decay rates of the tested rocks rose with an increase in temperature and temperature difference (maximum–minimum), with the rank order of decay rate being J 3 t > K 2 m > J 1 l. Quantitative analysis revealed rock decay rate to be significantly related to temperature by a power function, and exponentially related to temperature difference. Our results suggested that temperature difference has a stronger effect on purple mudstone decay than that of temperature magnitude during the wetting–drying processes. [ABSTRACT FROM AUTHOR]

To meet the prospect of carbon neutrality, Deep borehole heat exchanger (DBHE) shows good potentiality in extracting deep geothermal energy for building heating, especially in densely populated urban areas of northern China. To investigate the influence on different soil thermal properties and system layouts of the DBHE array, a comprehensive numerical model has been established by OpenGeoSys software coupled TESPy toolkit and a series of scenarios are simulated. Results show that thermal conductivity lay a more important influence on heat extraction performance for DBHE array, rather than volumetric heat capacity. The thermal plume of DBHE array will grow larger along with higher thermal diffusivity. For typical geological parameters in Xi'an, the inter-borehole spacing should not be set below 15 m or it will bring a risk of freeze in circulation. The heat extraction performance and long-term sustainability of single-line layout are obviously better than other layout patterns, also with a smaller ground area needed to deploy the boreholes. This study implies that soil thermal conductivity is the core factor in determining the heat extraction performance of DBHE array and also gives suggestions for the system design of DBHE array in the aspect of borehole spacing and system arrangement. • Long-term performance evaluation under different soil thermal properties for DBHE array. • The level of soil thermal conductivity has a crucial impact on the heat extraction of DBHE array. • Radius of thermal plume after long-term operation increases with soil thermal diffusivity. • Proper inter-borehole spacing and arrangement geometry are suggested for DBHE array. [ABSTRACT FROM AUTHOR]

Abstract: The ventilation condition is one of the main factors that determine the Heat Release Rate (HRR). In order to reveal the influence of ventilation condition on the HRR of China Railways High-speed (CRH) passenger rail car and help the fire protection engineers to choose the right HRR during the fire risk assessment of high-speed rail system in China, the HRR and other thermal parameters of the individual materials and component assemblies of CRH passenger rail car, are measured with the Cone Calorimeter and other test instruments, as the input parameters of Fire Dynamics Simulator (FDS), and 2 fire scenarios have been designed to obtain the HRR vs. time curves of CRH passenger rail car on the different ventilation conditions, such as the location and number of the open windows. The research results show that the ventilation condition exerts a significant influence on the HRR of CRH passenger rail car, which is in the range of 18.4∼37.9 MW according to the different ventilation conditions; if only one window is open, the closer the open window gets to the ignition source, the higher the HRR is; if several windows are open at the time, the HRR is the highest as 2 windows are open, which is 37.9 MW. The HRR of CRH passenger rail car dramatically fluctuates with the different ventilation conditions, so the HRR of CRH passenger rail car should be chosen and applied carefully. [Copyright &y& Elsevier]

Abstract: The 813-mm-diameter China–Russia Crude Oil Pipeline enters northeastern China at Lianyin, Mo''he County, Heilongjiang Province and crosses 441km of warm discontinuous, sporadic and isolated patches of permafrost and 512km of seasonally frozen ground before reaching Daqing, China. It is inevitable that the buried pipeline is subject to frost heave and/or thaw settlement when it passes through regions of permafrost and seasonally frozen ground with available moisture. Therefore, stress and deformation analyses of the pipe subject to frost action or thaw settlement are important for the safety, long-term stability and economic feasibility of the buried oil pipeline system. Based on the (empirical) frost heave and/or thaw settlement coefficients, a simple thermal elasto-plastic finite element computation model is put forward for analyzing the stress and strain state of the pipe. The influences of soil temperatures on the soil deformation were considered, but those of the soil deformation on the soil temperatures were ignored in the modelling. Finally, two examples of the application of the computation model are presented, in which the stress and deformation of a pipe exposed to frost heave or thaw settlement is calculated. The results of the frost action computation show that the effective stress on the pipe increases linearly with the frost heave deformation. The largest pipe deformations and stresses may occur when crossing frost mounds due to differential frost heaving. The stress and deformation smooth out from the frost mound. The results of thaw settlement computation show that the pipe stress changes greatly near the interface of thaw settlement zone and no thaw settlement zone, and the thaw settlement has small effect on the stability of oil-pipeline. The computation results show that the oil pipeline design in the permafrost regions should pay more attention on frost heave hazard than thaw settlement hazard. [Copyright &y& Elsevier]

Abstract: The China–Russia Crude Oil Pipeline (CRCOP) faces significant challenges due to differential frost heaving and thaw settlement resulting from significant variations of oil temperatures along the pipeline. Oil temperature distribution along the pipeline during the long-term operation period is a very important factor in pipeline foundation design under future climate warming and various frozen soil conditions. It is important for the assessment and prediction of differential frost heave and thaw settlement of the pipeline foundations soils, forecasting the development of the seasonal and inter-annual frozen and thawed cylinders around the operating pipeline, stress–strain analysis of the pipeline, and mitigation of subsequent frost hazards. A quasi three-dimensional computational model was developed to predict the oil temperature along the pipeline. It was verified by analytic solutions of the minimum oil temperatures along the route provided by the Daqing Oilfield Engineering (DOE) Co. The oil temperatures were predicted and analyzed for two proposed annual oil flow rates of 15million tons (0.3mbpd) and 30million tons (0.6mbpd) with and without mitigative measures (only pipe insulation was considered here) during the operation period. Also, the inter-annual variations of oil temperature at key typical locations were investigated to understand the impact of climate warming. The results indicated that the maximum oil temperature cools southwards, but the minimum oil temperature warms southwards (with the inlet oil temperatures from −6 to +10°C). However, the average annual oil temperature decreases southwards in the northern part of the pipeline, then it starts to slowly increase. The amplitudes of oil temperature change will decrease southwards. Oil temperatures will slightly increase with elapsing time due to the imposed boundary conditions of climate warming. The oil temperatures with a lower flow rate vary more significantly than that with a higher flow rate because the oil temperature with a low flow rate is more affected by the thermal regime of the surrounding soils and the external environments. Insulation around the pipeline tends to reduce the oil temperature variations along the pipeline during pipeline operation period. Therefore, pipe insulation can effectively reduce the development of frozen and thawed cylinders in the permafrost zone. The phase change of water in soils around the pipeline has a distinct influence on the oil temperature during the freeze–thaw transition periods. The oil temperature tends to be equal to the ambient ground temperature around the pipeline with southward distance and with elapsing operation time. The pipeline oil temperature is controlled by the incoming oil temperature and the surrounding ground temperature before the equalization. It would be mainly controlled by the ground temperature around the pipeline afterwards. [Copyright &y& Elsevier]

Abstract: Using the finite element method, thermal effects of the Chinese–Russian crude oil pipeline in permafrost regions were estimated under two construction modes (conventional burial and aboveground embankment), two thermal control techniques (bare and insulated pipe), and three climate conditions along the route (marked under the natural mean ground surface temperatures of −0.5, −1.0, −1.5°C, respectively). The results show that with the silt embankment on gravel berm and the insulated pipe, the thaw of permafrost under the pipeline could be prevented during its service life. However, thawing of the permafrost under the conventionally buried pipeline cannot be prevented regardless of climate conditions or thermal insulation around the pipe. So it is strongly recommended that over-excavation and/or thermosyphons be applied for the conventional burial construction mode, especially in the warm and ice-rich permafrost sections to mitigate frost heave and thaw settlement in the subsoil. [Copyright &y& Elsevier]

Abstract: Permafrost accounts for about 52% of the total area of the Qinghai–Tibet Plateau, and the permafrost area is about 140×104 km2. The mean annual ground temperature of permafrost ranges from −0.1 to −5°C, and lower than −5°C at extreme high-mountains. Permafrost thickness ranges from 10 to 139.4m by borehole data, and more than 200m by geothermal gradients. The permafrost geothermal gradient ranges from 1.1°C/100m to 8.0°C/100m with an average of 2.9°C/100m, and the geothermal gradient of the soil beneath permafrost is about 2.8–8.5°C/100m with an average of 6.0°C/100m in the Qinghai–Tibet Plateau. For a minimum of permafrost geothermal gradients of 1.1°C/100m, the areas of the potential occurrence of methane hydrate (sI) is approximately estimated to be about 27.5% of the total area of permafrost regions in the Qinghai–Tibet Plateau. For an average of permafrost geothermal gradients of 2.9°C/100m, the areas of the potential occurrence of methane hydrate (sI) is approximately estimated about 14% of the total area of permafrost regions in the Qinghai–Tibet Plateau. For the sII hydrate, the areas of the potential occurrence of sII hydrate are more than that of sI methane hydrate. [Copyright &y& Elsevier]

Extreme thermal environment harms the health of outdoor workers and poses a potential threat to workplace safety. A field survey, including thermal parameter measurements, was conducted at construction sites in South China during the summer of 2019. The relationship between health risk and thermal parameters was obtained. The thermal sensation and satisfaction rate of the workers at different outdoor environmental conditions were analyzed, and recommendations were made based on the comparison of thermal indices. The thermal stress categories of the thermal indices were also investigated. The results suggest that the intensity of working conditions should be reduced when the air temperature is higher than 34 °C; the satisfaction rate of workers was found to be relatively high when the outdoor temperature is lower than 34 °C and the wind speed is greater than 1.3 m/s. Thermal indicators used to evaluate the comfort level of outdoor workers need to be modified according to the local climate and working environment to avoid excessive exposure to high-temperature work environments. • Extreme thermal environment harms the health of outdoor workers. • Thermal parameter measurements were conducted at construction sites in summer. • Labor intensity should be reduced when temperature is higher than 34 °C. • At air temperature <34 °C and wind speed >1.3 m/s, satisfaction rate of workers is high. [ABSTRACT FROM AUTHOR]

Abstract: Under the impact of potential climate warming and human engineering activities, the Embankment with Crushed Stone Slope Protection (ECSSP) needs further countermeasures to protect the underlying permafrost along the Qinghai–Tibet railway in warm (−1 to 0 °C) permafrost regions according to the observed in situ data. In this paper, a new strengthening countermeasure, the Embankment with Shading Board and Crushed Stone Slope Protection (ESBCSSP), is proposed to cool the foundation soil and to protect the warm permafrost. The crushed stone layers placed on the side slopes of the embankment have an apparent “thermal semi-conductor” effect by intensive natural convection of pore air in the winter and a “heat shield” effect in the summer. The shading boards erected on crushed stone slope protection can shade the ground surface from the sun to lower its surface temperature, and can keep snow from covering the crushed stone layer in the winter, which can enhance the cooling effect of the crushed stone layer. Based on the processes of natural convective and conductive heat transfer in porous media, systemic numerical tests were performed to study the cooling effect of the ESBCSSP, and to propose the reasonable range in thickness, height and grain size of the crushed stone slope protection. [Copyright &y& Elsevier]

Due to the continuous development of underground engineering (underground surrounding rock stability, hot dry rock production, etc.), the thermal damage of granite has attracted much attention. In order to explore the effect of heating up to 800 °C on the physical properties, such as mass, color, roughness, wave velocity, thermal diffusivity, and thermal conductivity, of granite in China, the results indicate that the physical properties of granite change significantly with an increase in temperature. The surface roughness, cracks, heat capacity, lightness, and coordinates a ⁎ (green-red) and b ⁎ (blue-yellow) show a significant increase between 400 °C and 600 °C. However, the thermal diffusivity, thermal conductivity, and P-wave velocity decrease as the heat treatment temperature increases, especially after 400 °C. By using numerical simulation, it is found that the heat transfer in the Luhui granite is affected by the heat treatment temperature and thermal conductivity. When the heat treatment temperature is lower than 500 °C, the heat transfer rate increases with an increase in temperature; on the other hand, when the heat treatment temperature is higher than 500 °C, the heat transfer rate decreases with an increase in temperature, and 500 °C is considered as the critical temperature. • Temperature has a great influence on the granite surface color, roughness and cracks. • The thermal conductivity and thermal diffusivity decrease significantly above 400 °C. • Thermal damage affects the heat transfer rate, and 500 °C is the turning point. [ABSTRACT FROM AUTHOR]

• Complete dataset of thermal properties of evaporites from the Kuqa foreland basin of China was measured. • Different mixing mean models are evaluated with measured thermal properties of sedimentary rocks. • Contrasting thermal properties of evaporites strongly influence basin geothermal regime. Many hydrocarbon reservoirs show a strong relationship with evaporitic rocks worldwide. Data regarding the thermal properties of evaporitic rocks are crucial for temperature prediction and basin modelling of salt-bearing sedimentary basins; however, their systematic measurement remains limited. This study reports a complete dataset of thermal properties of 20 evaporitic and clastic rocks from the Kuqa foreland basin, a typical Cenozoic salt-bearing basin with prolific hydrocarbon potential in northwest China. The results indicate that gypsum and rock salt have the lowest and highest thermal conductivity (1.57 ± 0.04 and 4.51 ± 0.73 W/m·K, respectively) and clastic rocks have an intermediate mean of 1.87–2.78 W/m·K. The average radiogenic heat production of evaporitic rocks is 0.10–0.14 μW/m3, remarkably lower than that of clastic rocks (1.33–1.38 μW/m3). Accordingly, thermal properties of the sedimentary rocks show a large variability in lithology. The mineral composition and porosity influence the thermal properties, and the geometric mixing model is confirmed to well predict the thermal properties of sedimentary rocks. Contrasts in the thermal properties between evaporites and other common sedimentary rocks could change the basin's geothermal regime. This new dataset of thermal properties of evaporitic rocks provides parameters necessary in accurate basin modeling for salt-bearing basins. [ABSTRACT FROM AUTHOR]

• Biochar caused significant decrease in thermal conductivity and thermal diffusivity. • Model prediction of soil thermal properties depends on sand size and biochar content. • Prediction of thermal conductivity improved with a decrease in quartz content in sand. • Averaging soil organic matter and biochar improved prediction of thermal conductivity. Little information is available on the effect of biochar on both measured and model-predicted soil thermal properties although they play a crucial role in the accumulation and transfer of heat and water through the soil. This study aimed at evaluation of the impact of biochar addition on soil thermal properties in field experiments conducted in China and Poland. The experimental data included biochar doses, soil texture, quartz and other minerals, bulk density, particle density, water content, air-filled porosity, and organic matter content. The data were then used to validate three models (analytic of de Vries, analytic of Zhao et al., and statistical-physical) and improve the predictability of the soil thermal properties. The biochar doses in the field experiments were from 4.5 to 40 Mg ha−1 and those in the modelling study ranged from 52 to 267 Mg ha−1. Pure biochar was used as well. The biochar additions caused a significant decrease in thermal conductivity and thermal diffusivity and exerted a less pronounced effect on the heat capacity. As shown by classic statistics and Bland-Altman plots, the agreement between the predicted and measured heat capacity of the Chinese soil was good and similar to the Zhao et al. and de Vries models. The best agreement between the statistical-physical model predicted and measured the thermal conductivity and diffusivity was obtained using the geometric mean of the native soil organic matter and biochar and after reduction of the quartz content in the sand fraction (2–0.05 mm) from 100 to 72%. The thermal diffusivity decreased with increasing biochar dose at comparable water contents and its characteristic maximum shifted towards higher water contents with increasing biochar dose. As thermal diffusivity enhances the smoothing of the temperature wave, these results imply that application of different biochar rates may help in regulation of soil temperature, which is an essential determinant of plant growth and soil processes and functions. [ABSTRACT FROM AUTHOR]

• A series of typical residential building models were defined through statistic method. • The envelope's size, shape, thermal properties and opaque feature were determined. • The indoor space partition and function area distribution were also identified. • The models could serve as a standard platform for building energy simulation research. • The method can be applied to other regions and building types with sufficient data. With the rapid growth of urban population in the Pearl River Delta (PRD) region, the research on residential energy saving has attracted increasing attention. Typical buildings are useful tools for building performance simulation of residential district, which is of great significance for local green building-related research, policy formulation as well as market orientation. In this paper, the spatial information (building size, shape, area and amount of dwelling unit area) and the thermal properties of the envelope (such as window-to-wall ratios, shading coefficient, and the heat transfer coefficient) of about 120 residential districts were collected and statistically analyzed. Meanwhile, 120 residential districts are the actual data in the PRD region since 2010. The analysis method involved K-means, histogram and bubble diagram, box plot - bin mean method and slope method, which aims to remove outlier points and find representative value for each parameter, and define a series of typical residential building models. From the analysis result of 120 residential districts, which involved around 350 types of 1300 residential buildings and over 900 types of dwelling units, 7 typical residential building models were determined to be used in other research. [ABSTRACT FROM AUTHOR]