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The cleaning potential of selected Chinese bituminous coals during coal preparation was evaluated in terms of coal quality, cleaning grade, and cleanability. The cleaning potentials were determined for coals sampled from a total of six seams, two each in three different general exploration areas in southern Shanxi, China. Distribution maps of resources with different cleaning potential characteristics were prepared using mapping and geographical information software. In each case, the area and calculated reserves for coals having different classifications of cleaning potentials were determined. The total areal extent of the six coals studied is about 410 million m2, and the total reserves of these coals amount to about 1460 million tonnes, which include coals of poor, fair, good, and proficient cleanabilities. The proportion of high-quality coals is about 28.9%. Coals that can be processed into high-quality coals account for about 69.2%. A cleaning potential gradient is proposed for indicating the cleaning potential level, and an equation for calculating it is established. The necessity of processing raw coal of good quality is also to be considered in terms of economics. It does not make economic sense to process coal with an organic sulfur content more than 1.5%, even though it may have a good cleanability.

HighlightsThe placement and operation of exhaust fans was assessed using CFD simulation.The effective temperature was used to evaluate the indoor thermal environment.The placement and operation of the exhaust fans mainly affected the airflow patterns in the part of the layer house closest to the fans.Abstract. The thermal environment inside a layer house significantly affects the growth, production, and health of the hens. Tunnel ventilation systems have been widely applied to control the indoor climate and air quality for large-scale poultry facilities around the world. Generally, only a few of the exhaust fans operate during mild seasons (spring and fall) in a tunnel-ventilated layer house depending on the outside air temperature. The decision about which exhaust fans to turn on affects the indoor airflow pattern and temperature distribution. However, little research has been reported that investigated the effects of the locations of exhaust fans on ventilation performance. In this study, a computational fluid dynamics (CFD) model was built and validated using field-measured data. The CFD model was then used to evaluate different ventilation strategies (combinations of exhaust fans) in a typical tunnel-ventilated layer house during the fall. The effective temperature was used to assess the performance of different ventilation strategies. Results showed that the locations of the exhaust fans significantly affected the indoor thermal environment, especially in the part of the house closest to the fans, because different locations of operating fans can generate different airflow patterns and affect the airflow through the animal-occupied zone. Based on the simulations, we conclude that the placement and operation of the exhaust fans can be optimized. Turning on the fans that are lower to the ground or near the sidewalls will result in more air bypassing the animal-occupied zones. Our results can help select the best ventilation strategy during the spring and fall in layer houses with tunnel ventilation systems. Keywords: Airflow distribution, Effective temperature distribution, Indoor thermal environments, Ventilation strategy.

Effective ventilation reduces heat stress in sows. A numerical study was carried out to investigate the effects of airspeed and direction on the convective heat transfer around a sow having different postures and body mass. The convection characteristics of a sow were analysed in a virtual wind tunnel using computational fluid dynamics (CFD) tools. The four postures of the standing, sitting, reclining and lateral lying were included. The investigated sow masses ranged from 130 kg to 340 kg. The results show that: 1) The general convective heat transfer was higher when the sow was standing or sitting postures rather than in a reclining or lateral lying posture; 2) Wind direction affects the sow convective heat transfer coefficient. The convective heat transfer coefficient of a sow was largest when it was standing or sitting with the body axis 60° to wind direction. When reclining or lateral lying sow axis at 45° to wind direction, the convective heat transfer coefficient was the largest; 3) The convective heat transfer coefficient of a single sow can be used to predict the convective heat transfer coefficient of a sow amidst rows of multiple sows; 4) Sow body mass negatively affects the convective heat transfer coefficient; 5) The convective heat transfer coefficient of the sow's trunk is relatively low compared with other parts such as the legs, head etc. Based on these results, when a sow needs to be cooled during hot conditions, an oblique airflow is recommended, and airflow speed around the sow's trunk should be increased as much as possible.

The effects of geological factors on the cleaning potential of Chinese bituminous coals from Anping, Xizhuang, and Yitang exploration areas were studied. The cleaning potential was evaluated in terms of coal quality and cleanability. Distribution maps of resources with different cleaning potentials were prepared using mapping and geographical information software. To identify the geological factors responsible for the cleaning potentials of coal resources, the distribution of coal resources with different cleaning potentials was summarized with regard to the geological setting of the three exploration areas. The results are as follows: The depositional environment may have a large role in affecting the cleanabilities of coals, but it may not be the only factor. Coal which formed in an environment prone to producing pyrite can have a better cleanability than coal formed in a depositional environment that is more prone to producing organic sulfur. In contrast to the effects of depositional environment, the local structures (e.g., folds, faults, and collapse columns), where present, are generally considered to have little, if any, effect on the distribution of the coal with different cleaning potential characteristics.

The discharge coefficient (Cd) of an opening is an important parameter in the application of the orifice equation to calculate the airflow rate of naturally-ventilated buildings. It is questionable to regard Cd as a constant under varied external airflows for large openings that are often applied in dairy buildings. This study investigated the impact of external wind speed and wind direction on the discharge coefficient of the windward sidewall opening with various opening sizes for a scaled naturally-ventilated dairy building model. The investigations were performed with Computational Fluid Dynamics (CFD) simulations. A set of data from wind tunnel experiments with a building model was used for the CFD model validation. The simulation results indicated that the discharge coefficient was almost unaffected by outdoor wind speed but varied considerably with the wind direction. Lower Cd values were observed for smaller wind angles. The pressure distributions on sidewalls were non-uniform. It is concluded that in the application of the orifice equation in oblique wind directions and large openings, the discharge coefficient is required to be specified instead of using the constant value, and it is necessary to distribute enough pressure taps along the horizontal direction to obtain the representative pressure difference.

The respiratory health and comfort of animals are closely associated with the air quality of their living environment. The aim of the present work is to identify the relationship between animal sounds and air quality of their living environment. Cough sounds of 84 weaners and four important aerial factors (i.e., air temperature, relative humidity, ammonia concentration, and dust concentration) were measured. The resulting power spectral density (PSD) showed a significant difference in cough sounds from weaners under different air qualities. Moreover, the developed recognition algorithm, using mel frequency cepstrum coefficients (MFCCs), principal component analysis (PCA), and support vector machine (SVM), provided an average recognition rate of 95% for sound samples collected in different pig houses. The results indicate that the cough sound analysis can provide qualitative information about the situation of the air quality in commercial livestock buildings.

This study investigated the physicochemical properties of the particles in a typical commercial laying hen barn in Southeast China. Mass concentrations and size distributions of the particulate matter (PM) and the key components (incl. organic carbon (OC), element carbon (EC), and the water-soluble inorganic ions (WSIIs)) were analyzed. The result shows that the mass concentrations of PM accumulated along with the airflow inside the house, with the total mass of the sampling particles increasing from 843.66 ± 160.74 μg/m3 at the center of the house to 1264.93 ± 285.70 μg/m3 at the place close to exhaust fans. The particles with the aerodynamic equivalent diameter, Dp > 9 μm, coarse particles (2.1 μm

Partitioning behavior of 17 deleterious trace elements in Ge-rich coals during coal combustion was studied in a bench-scale combustion apparatus in a laboratory and in full-scale combustion in a coal-fired power plant. Methods used in this study include spectrophotometry, tube furnace combustion, inductively coupled plasma mass spectrometry (ICP-MS), and statistical evaluation. A comparison of the results obtained at these two scales and of the factors affecting their volatilization behavior during combustion are discussed. These seventeen trace elements tend to be volatilized more completely during combustion in coal-fired power plant than in a laboratory-scale combustion environment due to the differences in operating conditions. The average proportions of elements going into fly ash from feed coals during combustion are positively correlated with the trace element volatilities. Volatilization behavior of trace elements in laboratory-scale combustion involves three stages: initial release ( 1,000 ℃). The seventeen trace elements can be classified into four groups according to their behavior during the above-mentioned stages. Factors affecting behavior of elements in combustion, such as combustion conditions, modes of occurrence, concentrations, and geochemical affinities, are discussed. A new insight into the behavior of potentially deleterious trace elements during combustion is given, which provides further guidance to controlling their emissions.

Baffles are often installed in mechanically cross-ventilated barns to combat heat stress by enhancing the cooling effect produced by the barn’s design. How effectively these baffles operate during warm weather often depends on where each baffle is located and at what angle it is set. Currently, their location and orientation are determined primarily according to the personal experience of the contractor in charge of installing the barn’s ventilation system. This study seeks to quantify the extent to which the location and orientation may affect the efficiency of the installed baffles. Computational fluid dynamics was used to create a three-dimensional model of a typical low-profile, cross-ventilated dairy barn. Differences were evaluated using both heat transfer and heat stress index (the Equivalent Temperature Index for Cattle - EITC). The results obtained from the tested scenarios indicated that installing the baffles above the animal occupied zone (AOZ) could indeed increase the air velocity (from less than 0.5 m s−1 to around 3 m s−1 once baffles were in place), and could also greatly increase (by 21.1%–50.9%) the amount of heat removed, while reducing the EITC by ~6 °C. In comparisons between the most commonly used scenario (in which baffles were installed vertically in the middle of the AOZ), and the other with-baffle-scenarios, the rate at which heat was removed from the cows varied by −3.0% to 2.6%, with the maximum difference being 172.4W. However, these scenario produced no significant improvement comparing with the commonly used one. The results obtained should provide a more reliable reference for engineers engaged in designing large-scale dairy barns.

Limited available land for livestock farming and increasing land-use costs have forced some large animal feeding operations to build animal barns from conventional one-floor to multi-floor in China recently because multi-floor animal building (MFAB) has a great advantage in saving land utilization. The ventilation system is an important part of animal building determining the indoor environmental condition. The difference in ventilation rate between MFAB and conventional barn might exist, because of the difference in building structure, especially due to the confined space outside of exhaust fans in the MFAB. However, a limited number of studies have accumulated information on the ventilation performance of this novel multi-floor animal barn. This work aims to acquire such information relating to the ventilation performance of a novel MFAB with a different number of floors (6, 7, 8, 9, and10 floors building) and different width of the yard using the Computational Fluid Dynamics (CFD) technique. A field measurement was carried out in a six-floor pig barn, and the measured air velocities were used for the CFD model validation. The validated CFD model was then extended to explore the difference of airflow patterns and ventilation rates on different floors under a different number of floors and the width of the yard. The simulation results showed that the difference in airflow pattern among each floor was limited, but the ventilation rate of each floor varied from floor to floor under the studied type of MFAB. The ventilation rate on the first floor was the lowest and increased with the floor increasing. Hence, more focus on the ventilation rate of the first floor should be paid during the design procedure. The increase of the floor number negatively affected the performance of the ventilation system because of the pressure profile in the yard of the building. Increasing the width of the yard could mitigate the negative effect of the floor number on the ventilation rates. Therefore, to perform the desired ventilation rate for animals in a multi-floor animal building required a more detailed design of the ventilation system of each floor by considering either the space available after exhaust openings or additional fans.

Litter decomposition is a key process of nutrient cycling in ecosystems, and has been studied in a wide range of grasslands, including the steppes on the Mongolian Plateau. However, information is hardly available on the responses of grassland litter decomposition to different land-use types, especially if the litters produced from grazing or mowing grasslands have home-field advantage in decomposition. In a five-year field experiment examining the effects of land-use types on grassland ecosystems in central Inner Mongolia, we determined the litter decomposition rate and quality indicators of three dominant steppe plants (Leymus chinensis, Stipa krylovii and Cleistogenes squarrosa) produced in grazing, mowing or enclosed grasslands, both in their respective home habitats versus in reciprocally displaced habitats. We found that (i) the litters from the grazing grassland had higher decomposition rate than that from enclosed grassland, especially when all litters were placed in the enclosed grassland; and the decomposition rate was negatively related with the C/N ratio, lignin concentration and lignin/N ratio in litters (P

As an interface between the animal occupied zone and the manure pit, the slatted floor has significant influences on gaseous emissions in livestock buildings. Airflow motion above the floor may affect the air motion in manure pit under the slatted floor. This work aimed to investigate the effect of slatted floor layouts on the airflow pattern in a manure pit and the corresponding ammonia emission from the pit by means of the Computational Fluid Dynamics (CFD) simulations. Firstly, airflow patterns of the 1:8 model and 1:1 model under the same Reynolds number and jet momentum ratio conditions were compared. Then, airflow patterns and ammonia emission rates of the 1:1 model with both parallel and perpendicular slatted floor layouts in various velocities (from 0.1 to 1.6 m s−1) were investigated. The results showed that the airflow patterns between 1:8 and 1:1 model were different when either the Reynolds number or the jet momentum ratio was same. On the other hand, the flow pattern in the pit with parallel floor was very different from that in the pit with perpendicular floor, resulting the ammonia emission rates different. For the cases with the free stream velocity of greater than 0.8 m s−1, perpendicularly arranged slatted floor released less ammonia from pit than the parallelly arranged slatted floor did (up to 39.0% less when free stream velocity was 1.6 m s−1). When the free stream velocity was lower than 0.8 m s−1, the perpendicular floor layout resulted in more ammonia emission than the parallel floor layout. It was concluded that the scale effect should be carefully considered during scale model experiments and the layout of slatted floors should be properly designed based on the air velocity in the animal occupied zone.

Access to inexpensive cooling sources is a precondition for developing cost-effective methods to mitigate heat stress among farm animal under hot climate conditions. The earth-air heat exchanger (EAHE) is a promising energy-effective technique that can be used to reduce the cooling load of a livestock building in hot days. Several studies have been carried out to assess the feasibility of EAHE for tempering air in livestock buildings. However, no mathematical model serving for EAHE design for livestock buildings has been developed, in which the EAHE system is often operated continuously to keep animals comfortable and productive. This work firstly deduced a regression model for predicting the air temperature difference between an EAHE tube inlet and outlet (ΔTi-o) using response surface methodology (RSM) based on the data obtained from validated steady-state numerical simulations. Four key design and operation factors (tube diameter, tube length, air velocity, and the temperature difference between inlet air and the undisturbed soil) were incorporated into the model. Based on the regression model, a mathematical model for predicting the cooling capacity (CC) of an EAHE tube was obtained. Parametric analysis was conducted to reveal the effects of the four factors on both the ΔTi-o and the CC. The models on cooling performance allow the designers to optimize the EAHE configuration for cooling livestock buildings.

An effective ventilation system can mitigate the heat stress suffered by dairy cows by increasing the rate at which heat is transferred convectively from a cow into the air flowing around the animal. To achieve a better understanding of the main factors involved in the heat-transfer process (i.e., the cow's posture and the airflow magnitude and direction), numerical investigations were conducted during the course of this study. By applying a computational fluid dynamics (CFD) modelling method, a virtual wind tunnel, and simplified geometric models representing a standing cow and a reclining cow, the heat transfer associated with a typical cow was simulated and analysed. The shear stress transport (SST) k–ω turbulence model was adopted, and it was shown that using a CFD method to analyse the heat-transfer data generated by this setup could produce results that are accurate and support the following conclusions: 1) airflow speed has a positive effect on the convective heat-transfer coefficient associated with both postures; 2) airflow direction affects the convective heat transfer coefficient, with the largest coefficient occurring in the cross flow case and the lowest in the downward airflow case; 3) the effect of posture on the convective heat transfer coefficient in a horizontal airflow is limited, whereas the effect in a downward airflow is relatively significant. However, the rate at which heat dissipates from a standing cow is greater than that of reclining cow, since a standing cow has more surface area in contact with the air. Based on these conclusions, it is recommend that, to cool cows under hot conditions, the airflow in the animal-occupied zone should be increased and that using a horizontal airflow to target the animal occupied zone should be encouraged whenever it is feasible to create.

Hot weather can stress livestock. The damage is even more serious when the heat is combined with heavy humidity. The wet-pad evaporative cooling systems commonly adopted in southeast China are considered an ideal method to overcome these severe environmental conditions. In this study, the hygrothermal conditions in a farrowing room with a wet-pad cooling system were evaluated with experimental and computational fluid dynamics (CFD) techniques. The field measurements were conducted in the summer to obtain air velocity, temperature, and relative humidity data. The average respiratory rate of the sows was measured to assess the hygrothermal comfort of the animals. Simulation of the indoor environment of the sows and piglets was conducted using commercial CFD software (ANSYS-Fluent 14.0) in which the boundary conditions were specified using the on-site measurements. Predicted temperature and relative humidity were validated against the measured data with a maximum error of less than 7.44%. CFD analysis of the hygrothermal conditions showed that the use of wet-pad cooling resulted in decreased air temperature and increased relative humidity around the pigs. However, the results demonstrated that the existing cooling system design did not meet the preferred thermal conditions for the animals, and suggestions were made for future research in wet-pad cooling systems.