Search

Brining is of great significant for extending the shelf life and maintaining the quality of aquatic products, but the freezing and thawing process of brined aquatic products needs to be explored based on changes in the thermal properties of the raw materials. Yellow-fin tuna slices were immersed in NaCl solutions with mass volume fractions of 0.00% (CK), 1.44%, 2.88%, 5.75%, and 11.50% for a duration of 2 h to study the effects of brining on the density, specific heat capacity under different temperatures, and refrigerated tempering and radio frequency (RF) tempering were used to thaw brined tuna. Additionally, both conventional refrigerated and radio frequency (RF) tempering methods were employed. The results showed that with the mass fraction of salt in the brine solution increasing, the density of the fish firstly decreased and then increased, while specific heat capacity and thermal conductivity gradually decreased, and the dielectric constant and dielectric loss factor increased progressively. The tempering rates of both refrigerated and RF tempering decreased with the increasing of salt levels in the brine solution, with RF tempering significantly outpacing refrigerated tempering in terms of speed. Refrigerated brining exhibited superior uniformity compared to RF tempering, although the uniformity of RF tempering improved as the salt level in the brine solution increased. These findings laid foundation for exploring RF tempering processes of brined yellow-fin tuna, and was helpful for improving uniformity and enhancing tempering quality in further. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phase change materials (PCMs) are the core media of energy storage for latent heat storage. Thus, screening of appropriate PCMs needs to take into consideration a variety of factors, whereas phase transition temperature, energy storage density and thermal conductivity are the most critical factors during assessment of feasibility for PCMs. As evident by summarizing and comparing the characteristics of different categories of typical solid-liquid PCMs, multi-high- performance compatible composite materials is the development direction for PCMs' applications. Finally, based on the theoretical analysis, it concluded as that within the range of specified working temperature difference of 50 °C, the heat storage density per unit mass of common PCMs is no longer correlated with it's phase transition temperature when latent heat is ≥ 100 kJ/kg, and the higher of phase transition temperature of PCMs is, the wider range of the effective output temperature can be obtained by the system, and more flexible output of system becomes. The larger the latent heat of PCMs is, the more stable the heat discharging efficiency of the system is while varying the effective temperature. Therefore, within the temperature difference of 50 °C, the thermal energy storage system gains rather superior output performance with selection of PCMs under considering of it's higher latent heat, competitive average solid-liquid specific heat and higher phase transition temperature. [ABSTRACT FROM AUTHOR]

In order to efficiently recover and treat sulfuric acid waste produced in the industrial and agricultural production and utilization process, a combined system of mechanical vapor recompression (MVR) and vacuum membrane distillation (VMD) was proposed and designed in this paper. A compressor was employed to compress the secondary vapor evaporated from the sulfuric acid solution in the VMD module. Then, the compressed vapor with a higher pressure and temperature was used to heat the feed solution in the heat exchanger, which not only recovered the latent heat of internal secondary vapor but also saved the external heat source and cooling water. The proposed system could complete the entire evaporation process by itself, and realize the efficient recovery and utilization of sulfuric acid waste through the complement advantages of VMD and MVR. Firstly, mathematical models were established in the light of the mass and energy conservation principles, the system experimental setup was constructed and then the experiments were carried out to verify the accuracy and reliability of the established mathematical models as well as the feasibility of MVR coupled with VMD. Then, the calculation program of thermodynamic performance was then developed and solved by the iteration with the aid of the Matlab software. The effects of operating parameters including feed concentration, feed temperature, feed velocity and permeate side pressure on thermodynamic characteristics were investigated. The following conclusions could be obtained: A series of experiments were carried out with the tap water as feed, under the conditions of feed temperature, feed velocity, permeate side pressure and heat transfer temperature difference of heat exchanger were 358.15 K, 2.8 m/s, 54 kPa and 2 K, membrane flux and condensate water conductivity were tested to be 1.6 kg/(m² ·h) and 48 μS/cm, and specific heating energy consumption (Shec) and performance coefficient (Cop) were found to be 71.88 kWh/t and 8.88. The simulated results indicated that when the heat transfer temperature difference of the heat exchanger was constant, increasing the feed concentration increased the saturation temperature difference between inlet solution and outlet vapor of the VMD module (ΔTVMD) and saturation temperature difference between inlet vapor and outlet vapor of the compressor (ΔTcom), which led to the increase of the compression ratio and power consumption of the compressor while the decrease of the Cop; increasing the feed temperature, feed velocity and permeate side pressure would decrease the values of ΔTVMD and ΔTcom, resulting in the decrease of the compression ratio and power consumption of the compressor while the increase of the Cop. Compared with single-effect evaporation, double-effect evaporation, three-effect evaporation and MVR systems, the separation efficiency of VMD, Heat pump-VMD and MVR-VMD systems was up to 99.9%, with obvious advantages in separation performance. However, compared with VMD and Heat pump-VMD systems, the current MVR-VMD system was more efficient and energy-saving. Obviously, considering the characteristics of separation and energy saving, the MVR-VMD system has greater advantages and broad prospects for development and application. [ABSTRACT FROM AUTHOR]

Copyright of Energy Chemical Industry is the property of Energy Chemical Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There are many ways to reinforce the end of a shield tunnel. In order to reasonably select the reinforcement method of shield tunnel end in the construction site, this paper mainly studied the law of the freezing reinforcement of the shield tunnel end with a circular freezing plate, analyzed the development law of the temperature field of the freezing reinforcement of the circular freezing plate at the end of the shield tunnel by using finite element software, compared it with that of the square freezing plate, and the sensitivity analysis of the circular freezing plate was carried out. The results showed that: (1)The circular freezing plate was more conducive to the reinforcement of the soil at the end of the shield tunnel than the square freezing plate; (2) The closer to the freezing plate, the faster the cooling rate, the corresponding shortening of the freezing time, and the significant freezing effect; (3) The greater the thermal conductivity, the faster the cooling rate, the wider the freezing range, and the more conducive to freezing;(4) The greater the specific heat, the slower the cooling rate, and the longer the freezing time, which was not conducive to freezing ;(5) The freezing effect of the frozen soil curtain cannot be changed by changing the latent heat of soil phase change. The analysis results obtained in this study can provide a reference for actual construction in the future. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heat transfer research of supercritical methane in the micro-channel is of great significance to the refined design of hydrocarbon fuel precoolers. The effects of several boundary conditions, including heat flux, mass flow rate and system pressure, on the heat transfer characteristics of the supercritical methane in a horizontal microtube were experimentally studied. Besides, the enhanced heat transfer mechanism of supercritical flow was also numerically clarified. The results show that heat transfer enhancements are produced when the temperature of supercritical methane is close to the pseudo-critical temperature, and the mass flow rate and system pressure have a greater impact on the maximum heat transfer coefficient. There are two main reasons for heat transfer enhancement. One is that the large radial density gradient near the pseudocritical point leads to the generation of buoyancy, thereby the secondary flow is generated under the combined action of gravity and buoyancy, which enhances the fluid mixing. The other is that the specific heat of supercritical methane increases sharply, resulting in the greater capacity to absorb thermal energy. Finally, an empirical correlation for the prediction of supercritical methane heat transfer in microtubes is proposed, which provides support for the refined design of hydrocarbon fuel precoolers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Jilin University (Science Edition) / Jilin Daxue Xuebao (Lixue Ban) is the property of Zhongguo Xue shu qi Kan (Guang Pan Ban) Dian zi Za zhi She and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The conditioning and extrusion are important heat treatment process that affects the feed quality in the production of fish feed. In the mechanism research and process parameter optimization of the above process, as one of the basic thermal characteristics, specific heat is an essential parameter. The existing research about animal feed processing, mainly explores the variation of specific heat with processing parameters such as temperature and moisture content. But there is fewer research on specific heat prediction models based on nutritional composition. In order to improve the adaptability and accuracy of the model, this research comprehensively explores the influence of processing parameters (temperature, moisture content) and nutritional composition (protein content, fat content) on the specific heat of fish feed. The objectives of this investigation were to explore the thermal property of fish feed during processing, to regulate the heat supplement during conditioning and extruding, and to explore the adaptability of the existing specific heat prediction model that applied for livestock and poultry feed to fish feed that had high fat and protein content. The four main ingredients of fish feed formula were chosen, including fishmeal, soybean meal, wheat flour and soybean oil. Soybean meal and wheat were grinded using a universal grinder equipped with the 1 mm sieve, and all raw materials were passed through a 40 mesh screen. Fish meal and soybean meal were used as protein sources, and soybean oil was used as fat source. There were 9 diets with 3 crude protein levels (30%, 40%, 50%) and 3 crude fat levels (5%, 11%, 17%) to represent fish feeds with different feeding habits. DSC (Differential Scanning Calorimetry) was used to measure the specific heat of 9 diets in the temperature range of 20-120 ℃ and the moisture content range of 20%-26%, the influence rule of the above 4 factors on the specific heat was analyzed, and specific heat prediction model for 4 factors was constructed. The results showed that the specific heat of fish feed was significantly affected by moisture content, temperature, crude protein content, and crude fat content. The main order of each factor was, moisture content, temperature, crude protein content, crude fat content. The specific heat increased linearly with the increase of the water content and the crude protein content, but decreased linearly with the increase of the crude fat content. The specific heat had a non-linear relationship with temperature, which was a quadratic regression relationship. In all experiments, the specific heat of fish feed varied from 1.70 to 2.70 kJ/(kg·℃). Based on experimental data, a multiple regression model (R² =0.991) of specific heat that in relation to processing parameters (temperature and moisture content) and nutritional composition (crude protein content and crude fat content) was established. It can improve the adaptability of specific heat for livestock and poultry feed in the existing research. The prediction model can effectively predict the specific heat of fish feed within the range of this study variable. The research results can provide basic data for the establishment of heat transfer mathematical models of fish feed during conditioning and extruding, and also provide theoretical guidance for the adjustment of heat supplement parameters in the productive process. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Energy feedstuffs, the most important and indispensable components in the pelleted complete feeds, provide energy in the form of soluble carbohydrate, oil and fat. Energy feedstuffs mainly includes cereals, cereal brans, molasses, oil, tuber and tuberous root, among which corn, wheat, barley, sorghum, wheat/rice bran, pelleted cassava residue and beet pulp are widely utilized in diets for livestock and poultry. Knowledge of the thermal properties of different feedstuffs is required for designing and parameter optimization of thermal process such as conditioning and pelleting processing, especially when energy costs, pellet quality and uniformity are the main consideration. The specific heat, thermal conductivity and thermal diffusivity are the most important thermal properties. In this paper, eight energy feed ingredients (4 cereal grains: corn, wheat, barley, sorghum; 4 processed by-products: wheat bran, pelleted cassava residue, pelleted beet pulp, rice bran) were obtained from a feed mill in the suburb of Beijing, and ground in a mini-mill equipped with screens having a aperture size of 1.5, 2.0 or 2.5 mm to obtain feed meals with three particle sizes (except rice bran, which could pass through the 1.5 mm screen completely without being ground). The moisture content of all feed meal samples was conditioned to 12% wet basis in order to eliminate the effect of moisture content difference on thermal properties. The specific heat, thermal conductivity of feed meals at the temperature range of 25-100 °C were determined by DSC (differential scanning calorimetry) and KD2 Pro (thermal properties analyzer), respectively. Thermal diffusivity of feed meals was calculated using measured thermal conductivity, specific heat, and bulk density. Based on the experimental data, prediction models of three thermal properties as a function of temperature were established. The effects of particle size on thermal properties of feedstuffs were analyzed. The particle size of eight feedstuffs grinding through screens with aperture size of 1.5, 2.0 and 2.5 mm ranged from 257.61 to 511.79 μm, 325.65 to 594.83 μm and 335.28 to 671.05 μm, respectively, which increased significantly with the increase in mesh size. There were significant differences between the values of particle size of 8 feedstuffs through the same mesh size. The values of specific heat of 4 grain meals (passing a screen with aperture size of 1.5 mm) increased with temperature (25-100 °C) and ranged from 1.678 to 2.421, 1.644 to 2.402, 1.642 to 2.385, and 1.649 to 2.441 kJ/(kg·K), respectively. For wheat bran, cassava residue and beet pulp, the values were found to range from 1.621 to 2.540, 1.580 to 2.195, 1.746 to 2.351 kJ/(kg·K). The specific heat of rice bran raised from 1.966 kJ/(kg·K) at 25 °C to 1.985 kJ/(kg·K) at peak temperature (28.0 °C), then declined to 1.868 kJ/(kg·K) at end-set temperature (33.5 °C), and finally increased to 2.671 kJ/(kg·K) at 100 °C. There was no significant effect of particle size on the specific heat of all feedstuffs (P>0.05). The specific heat followed linear relationships with temperature at the range of 25-100 °C for 4 grains, and cubic polynomial relationships for wheat bran, cassava residue and rice bran, and a second order polynomial relationship for beet pulp. The values of thermal conductivity of 4 grain meals (passing a 1.5 mm screen) increased nonlinearly with temperature (25-100 °C) and varied from 0.089 to 0.299, 0.078 to 0.336, 0.088 to 0.276 and 0.082 to 0.288 W/(m·K), respectively. For 4 processed by-products, the thermal conductivity was found to raise from 0.054 to 0.190, 0.092 to 0.362, 0.085 to 0.263, and 0.064 to 0.202 W/(m·K), respectively. Significant differences were observed between the thermal conductivity of 8 feed mills (passing a 1.5 mm screen) at a higher temperature (85 or 100 °C), and the thermal conductivity of cassava residue was the highest, followed by wheat, wheat bran with the lowest value. For the same feedstuffs, the thermal conductivity of feed mills, at the same temperature, decreased generally with the increase in particle size, and the higher temperature, the stronger decrease. Cubic polynomial relationships of thermal conductivity with temperature (25-100 °C) were established for 4 grains and beet pulp with different particle sizes, and quadratic polynomial relationships were obtained for wheat bran, cassava residue and rice bran. The values of thermal diffusivity of 4 grain meals (passing a 1.5 mm screen) varied from 7.459×10-8 to 17.320×10-8, 6.694×10-8 to 19.195×10-8, 7.878×10-8 to 17.045×10-8, and 6.857×10-8 to 16.109 ×10-8 m2/s at temperature range of 25-100 °C, respectively. The values was observed to ascend from 9.543×10-8 to 20.892×10-8, 8.217×10-8 to 23.254×10-8, 7.258×10-8 to 16.646×10-8 and 8.092×10-8 to 18.718 ×10-8 m2/s for 4 processed by-products, respectively. In general, the thermal diffusivity of the 8 energy feedstuffs had a slow increase with temperature at the range of 25-55 °C, and a sharply raise with temperature at the range of 55-100 °C. The thermal diffusivity of all 8 feedstuffs tended to decline with increasing particle size. The thermal diffusivity displayed second order polynomial relationship with temperature at the range of 25-100 °C for wheat bran and rice bran, and cubic polynomial relationships for the other 6 feedstuffs. [ABSTRACT FROM AUTHOR]

The anti-symmetric thermoelastic instability model was developed to calculate the critical speed with the sliding condition of the perturbation fixed on friction components. The influence of material parameters such as elastic modulus and Poisson's ratio on thermoelastic stability of the friction system was studied. The model was verified by the finite element solution of Yi Yun-bo and Zhao Jianxin. The results show that the deformed discs have great influence on the process of shifting, however little effect on the creeping condition. Among the three kinds of friction discs, paper-based friction discs have the best thermoelastic stability, while the Cu-based friction discs are the worst. The critical speed increases with the increase of the specific heat, thermal conductivity of steel discs and thermal expansion coefficient of friction discs. On the contrary, the critical speed decreases with the increase of the other material parameters. Under the premise that the parameters of the separator discs remain unchanged, the stability of the friction system can be improved by decreasing the specific heat, Poisson's ratio, Young's modulus and thermal conductivity, meanwhile increasing the coefficient of the thermal expansion. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Space rocket engine nozzle usually has large area ratio, and the improvement in its performance is one of the goals of engine design. A design method for divergent section considering the changes in properties of the real fuel gas in nozzle is proposed based on the Rao’s method. For an apogee rocket engine, the Rao’s method is used to design an original nozzle contour, and then the function of specific heat of the real fuel gas is calculated and a new nozzle contour of divergent section of nozzle is designed.The vacuum specific impulses of the new nozzle contour and the original one are compared through numerical simulations. Simulated results show that the calculation method of fuel gas specific heat can be used for the nozzle flow simulation; the specific heat of fuel gas has great effect on the nozzle contour design; for the nozzles with the same length, the nozzle contour designed by considering the change in specific heat capacity has smaller exit area ratio, but has higher vacuum specific impulse; and for the space engine which has not too large thrust, the increase in vacuum specific impulse is less then 1s, and the gain of performance by the boundary layer displacement is very small. [ABSTRACT FROM AUTHOR]

In order to study the influence of the physical parameters of the thermodynamic properties of central adsorbed graphene-like bilayer materials, Heisenberg model is introduced. Under the framework of Heisenberg model, the materials are abstracted as a double layer ferromagnetic antiferromagnetic system with triangular structure model and a four sublattice. Using linear spin wave theory and the Green function method, the thermodynamic properties of the system are derived, and the internal energy and specific heat are solved numerically. The internal energy and specific heat increase with the increase of temperature. The internal energy decreases with the enhancement of the intralayer and interlayer antiferromagnetic exchange coupling, increases with ferromagnetic exchange coupling. The relationship between specific heat and exchange coupling and anisotropy are not linear. [ABSTRACT FROM AUTHOR]

To accurately evaluate the heat transfer effect and ensure the safe and stable operation of heat exchanger, a new heat transfer evaluation index η was proposed, which was equal to the ratio of convection heat transfer coefficient to the one-third power of pressure drop. With special consideration of the effect of pressure drop on heat exchange, the baffle structure was simulated and optimized by CFD software. The optimized baffle spacing was determined, and the optimized baffle cut height was then determined. The results show that with the increasing of baffle spacing and cut height, fluid velocity, pressure drop and convection heat transfer coefficient are decreased, while heat transfer evaluation index is decreased with latter increasing. The heat transfer effect is dependent on convection heat transfer coefficient and pressure drop. For the specific heat exchanger with the length of 1 632 mm, the optimal heat transfer effect was obtained under the conditions with baffle spacing of 350 mm and baffle cut height of 0.375D. The simulation results are in good agreement with the results of the baffle structure of heat exchanger in atmospheric-vacuum distillation unit of a refinery. [ABSTRACT FROM AUTHOR]

Whey powder is a kind of thermosensitive feedstuff, which is particularly prone to pyrogenation and protein denaturation in conditioning and pelleting processing of pellet feed for weanling pigs. Pellet mill can be blocked easily when the feed formulation is designed with high level of whey powder. Studies on thermal proprieties of whey powder and formula feed containing different levels of whey powder are required for parameter optimization in thermo processing of formula feed. As corn meal, soybean meal, whey powder and fish meal are the most common and important ingredients in the diet of weanling pigs, 33 kinds of formula feeds consisting of different levels of corn meal (22.6%-70%), soybean meal (13.7%-46%), whey powder (0-30%) and fish meal (0-10%) were obtained by D-optimal mixture design method in this work. Proximate composition of 4 ingredients including moisture, crude protein, crude fat, crude ash, crude fiber, starch, lactose contents was determined. The specific heat of these 4 ingredients at the temperature range of 25-120 ℃ and 33 kinds of formula feeds at 25-110 ℃ were measured by DSC (differential scanning calorimetry) at a programmed heating rate of 10℃/min, and the prediction models of specific heat as a function of temperature were established. Thermal denaturation of whey powder and formula feeds containing high levels of whey powder was also analyzed by DSC. The moisture contents of corn meal, soybean meal, whey powder and fish meal were 12.01%, 10.96%, 3.84% and 7.28% (wet basis) respectively, and the crude protein contents were 8.08%, 47.26%, 11.24% and 65.73% (wet basis) respectively. The specific heat of corn meal ranged from 1.614 to 2.705 kJ/(kg·K), soybean meal from 1.844 to 2.529 kJ/(kg·K), whey powder from 1.355 to 2.911 kJ/(kg·K), and fish meal from 1.592 to 2.464 kJ/(kg·K). Whey powder showed significantly lower values of specific heat at 25-100 ℃ compared to the other 3 ingredients, but significantly higher value at 120 ℃ (P<0.05). The specific heat of corn meal increased linearly with the increase in temperature, and that of soybean meal increased logarithmically with the increase in temperature. The specific heat of whey powder followed a cubic polynomial relationship with temperature, and fish meal displayed a quadratic polynomial relationship with temperature. The specific heat of formula feeds containing no less than 6.25% whey powder followed a cubic polynomial relationship with temperature, which was the same as that of whey powder. However, the specific heat of formula feeds containing no whey powder displayed a logarithmical relationship with temperature, similar with that of soybean meal. Analysis of variance showed that the specific heat of formula feeds was significantly dependent on temperature, ingredient proportion and the interaction of the 2 factors (P<0.001). Temperature had the most significant effect on specific heat, followed by the level of whey powder. An endothermic peak with an enthalpy of 4.14 J/g was observed on the DSC thermogram of whey powder, which may be caused by the denaturation of whey protein. The onset temperature, peak temperature, and termination temperature were 90.23, 109.79, and 115.25 ℃, respectively. During this thermal denaturation process, the specific heat of whey powder raised from 1.745 kJ/(kg·K) at onset temperature to 2.798 kJ/(kg·K) at peak temperature, and then declined to 2.662 kJ/(kg·K) at termination temperature. Whey powder particles exhibited a spherical shape with numerous bulges and micro pores on the surface after the thermal treatments of 20-90 ℃, but an irregular shape with smooth surface and agglutinate status after the thermal treatments of 110-115 ℃ based on micrographs obtained from the scanning electron microscope. Similarly, 20 kinds of formula feeds containing high levels (≥14.548%) of whey powder also displayed endothermic peaks on the DSC thermograms, but the onset temperatures (67.46-74.99 ℃), peak temperatures (77.95-87.69℃), termination temperatures (81.47-91.72℃) and enthalpy (0.38-1.00 J/g) were lower than that of whey powder. Mixture with corn meal, soybean meal and fish meal could decrease the thermal stability of whey powder and facilitate the denaturation of whey protein obviously. Consequently, in order to reduce the denaturation of whey protein and the blocking of pellet mill, the conditioning temperature of formula feed containing high level of whey powder for weanling pigs should be lower than 70 ℃. In addition, the onset temperature, peak temperature, termination temperature and enthalpy of formula feed were significantly positively correlated with whey powder content (r=0.697, 0.905, 0.903, and 0.946, respectively, P<0.001). This investigation provides fundamental theory and data for process optimizations of thermo processing such as conditioning, and pelleting of formula feed containing high level of whey powder for weanling pigs. [ABSTRACT FROM AUTHOR]

The cultivation of top-notch innovative talents is the important connotation of double top construction, and the research-based experimental teaching is an effective way to improve the practical ability and innovation ability of undergraduates. In the process of cultivating innovative talents, universities with industry background should focus on innovation and also base on industry characteristics. In this paper, the research-based experiment teaching is carried out in combination with the cultivation of innovative talents of undergraduates of China University of Mining and Technology with the mining features. The experiment process that students participate in or even dominate is introduced combined with experimental platform construction of specific heat pipe . The effect of experimental teaching is summarized and the thinking and suggestions are presented. It is hoped that it can be used for reference in the teaching reform of innovative talent cultivation, especially the experimental teaching. [ABSTRACT FROM AUTHOR]

Weaned piglet's pellet feeds are designed for healthy growth of weaned piglet. Conditioning is a key factor affecting pellet feed quality and pellet mill throughput, which can be defined as the process of transforming the physical state of the mixed mash with the addition of saturated steam to facilitate the compaction of the feed mash. Knowledge of the thermal properties of mash feed is required to perform the heat transfer calculations that are involved in the optimal design of conditioner and evaluation of operating parameters. Specific heat is an important thermodynamic parameter used in heat transfer and energy balance calculations. Conditioning processing involves broad temperature (25-95 ℃) and moisture content (12%-16.5%, wet base) ranges. The objectives of this investigation were to determine the specific heat of mash feeds for weaned piglet as affected by moisture content, temperature and grinding particle size. In this work, the specific heat of mash feeds for weaned piglet in 4 grinding particle sizes (geometric mean diameter of 346.34, 364.57, 388.93 and 404.25 μm, and sieve aperture of Φ1.0, Φ1.5, Φ2.0 and Φ2.5 mm) was measured as a function of moisture content (10%-18%) and temperature (25-100 ℃) by differential scanning calorimetry (DSC). The mash feeds were processed in Xinsanfeng feed mill in Miyun District, Beijing, while the determination of specific heat was conducted in China Agriculture University from April to November in 2015. As for the experiment design, the method of total experiment with full randomization was applied with 3 factors which included 4 kinds of grinding particle sizes (346.34, 364.57, 388.93 and 404.25 μm), 16 levels of temperatures (25, 30, 35 , 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100 ℃) and 5 levels of moisture contents (10%, 12%, 14%, 16% and 18%). The influences of these variables on the specific heat were analyzed and a prediction model of specific heat concerning these variables was established. The specific heat was found to be significantly dependent on moisture content, temperature and grinding particle size, and the effect of moisture content was greater than the other 2 factors. In addition, the specific heat was proved to be significantly dependent on the interactions of moisture content and grinding particle size/temperature. Specific heat of mash feeds over 4 grinding particle sizes increased in the range of 1.572-2.747, 1.533-2.783, 1.562-2.869 and 1.548-2.881 kJ/kg·K with the increase in moisture content and temperature respectively. Specific heat had a linear positive correlation with moisture content and a logarithmic correlation with temperature. At 25 ℃ and 85 ℃, the specific heat values of mash feeds over 4 grinding particle sizes varied in the range of 1.533-2.037 and 2.289-2.758 kJ/kg·K with the increase of moisture content respectively. The specific heat of mash feeds with higher grinding particle size (404.25 and 388.93 μm) was greater than that with lower grinding particle size, especially at high temperature (60-100 ℃) and high moisture content (18%). As the grinding particle size of mash feed is reduced, the surface area is increased geometrically. So per unit weight of mash feed with lower particle size will condense more heat and water. This will result in the mash feed with lower particle size having higher degrees of starch gelatinization and protein denaturation. The variations in state and components of mash feeds may contribute to the differences in specific heat. Regression models with high R2 values were established to predict the specific heat of mash feeds as a function of 2 dependent terms of only moisture content and temperature, and of 3 dependent terms of moisture content, temperature and grinding particle size. The inclusion of grinding particle size dependent term in the empirical equation is expected to enhance the predictive capacity of model at high moisture contents in comparison with that equation only including moisture content and temperature. The results provide basic data for the establishment of the heat-transfer equation in conditioning of feeds for weaned piglet, and offer theoretical reference for the optimization of process parameters in thermo-processing. [ABSTRACT FROM AUTHOR]