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Agricultural machinery is ever-increasingly either displacing or augmenting human labor with the development of the economy and technology. Among them, fuel efficiency has a significant impact on energy conservation and emission reduction, indicating high economic and social significance. Particularly, a tractor is one of the most typical agricultural machinery. In this study, the overall energy efficiency of tractors was evaluated under actual operating conditions. The performance of tractors was also measured comprehensively. The actual energy efficiency of tractors was clearly defined and calculated as well. The common operating points of tractor engines were extracted by K-means clustering and pairwise comparison matrix, according to the shortest distance partition. The energy efficiency of 186 162 kW tractors was analyzed to propose the classification standard using tractor energy efficiency. Energy efficiency limits and energy efficiency ratio limits were determined at all levels. The average energy efficiency was compared using different operating links. The results showed that there was a significant difference in the distribution and weight between the actual eight operating points and the ISO steady-state eight operating points. The main reason was that the ISO steady-state eight operating point was targeted at nonroad diesel engines, covering a wide range of engine models, power, and applications. However, the actual eight operating points were more specific, and refined for the actual operating conditions of multiple 162 kW tractor engines. The error range of tractor energy efficiency was −0.483-0.487 (kW·h)/kg using two datasets of working conditions. Therefore, the energy efficiency calculation was necessary and meaningful using the actual eight working conditions. In addition, there was a significant difference in the tractor energy efficiency using actual operating conditions, where 50% of tractor energy efficiency values were distributed in the range of 3.20 to 3.65 (kW·h)/kg, with an average value of 3.42 (kW·h)/kg. This difference was attributed to the driving habits of agricultural machinery operators, the tractor maintenance and repair levels, as well as the tractor age, resulting in the varying degrees of reduction in engine performance indicators. Then, the grading was constructed using the tractor energy efficiency, where 3.07 (kW·h)/kg was determined as the qualification limit of actual energy efficiency in the tractor. The limit values were also determined for the tractor energy efficiency ratio for levels 1-4. As such, the classification of energy efficiency levels was achieved for tractors. There was a significant variation in the average energy efficiency at different operation stages of each tractor. The rotary tillage mode presented the highest value of average energy efficiency, whereas, the walking mode was the lowest. The trend was attributed to the different engine loads of tractors at different operating stages. Therefore, there was great potential for the real-world energy efficiency performance of tractors from a user perspective. The actual operating performance of tractors was explored to establish an evaluation system applicable to the energy efficiency performance of tractors in the real world. The findings can provide the basic data for energy-saving and emission reduction in tractor engines. A strong reference can be also offered to assess the energy efficiency of agricultural machinery on application subsidy suitable for the level of green operation. [ABSTRACT FROM AUTHOR]

Marginal lands can greatly contribute to fully meeting the ever-increasing demands for cultivated resources in recent years. In general, the available marginal land refers to the new reclamation lands that converted from grassland, wetland or other lands in the past 25 years. Among them, there are serious land desertification and low productivity in Inner Mongolia of northwestern China, where the marginal land is widely distributed so far. Alternatively, Cyperus esculentus L. has been one of the most important crops to ensure the safety of grain and oil in China, due mainly to the high yield and oil content. Therefore, it is a new idea to promote the cultivation of Cyperus esculentus L. on a large number of marginal lands under a rapid development of mechanized agriculture. In this study, a multi-factor comprehensive evaluation was made to determine the cultivation and production potential of Cyperus esculentus L. in the marginal land of Inner Mongolia, further to predict the energy and economic benefits from the new oil crop. The results show that there was a total of 125 000 km² of marginal land in the study area, of which the area of first-class marginal land was 26 000 km², mainly distributed in the central and eastern Bayannur, Baotou, Xilinhot, and Tongliao counties. The types of land cover were the sparse vegetation, farmland and mixed vegetation. The area of second-class marginal land was 64 000 km², particularly distributed in Huolin Gol, and Wuhai City, where there were the vegetation-based farmland and vegetation mixed areas. The area of third-class marginal land was 35 000 km², mainly distributed in the desert edge areas of the western Alxa League. It was difficult to reclaim in some complex restricted areas with harsh climate conditions, due to the low rainfall and transportation. As such, approximately 15.9 million tons of edible oil was produced per year, when planting the Cyperus esculentus L. on these marginal lands. Otherwise, 1.87×1012 MJ of biomass energy was obtained, corresponding to the 44.7 million tons of fuel oil. On the whole, Cyperus esculentus L. presented great potential in the production of edible oil and biodiesel. Correspondingly, the marginal land can be widely expected to alleviate the shortage of edible oil, as well as the energy crisis in the realization of carbon neutral goals. The marginal land can also be fully utilized to alleviate the increasingly tense human-land contradiction for a higher land productivity. Since the industrial chain of Cyperus esculentus L. has not yet been fully mature, the accuracy of the estimation can increase with the promotion of plantation and industry, when evaluating the potential of planting, oil yield, and biomass energy production on marginal lands. The finding can also provide a scientific data support to the marginal land use, as well as the cultivation and promotion of Cyperus esculentus L. in the sandy areas of northwestern China, so as to alleviate the shortages of regional grain, oil and energy resources. [ABSTRACT FROM AUTHOR]

During the storage of fruits and vegetables, the uniformity of air distribution inside the cold storage store is crucial to affect both the storage quality of fruits or vegetables and energy efficiency of supply air. In the traditional cooling fan direct blowing air supply mode, some local air velocities and temperatures are easily to be larger than those required for cargo area, which would greatly reduce the uniformity of air distribution and the storage quality of fruits and vegetables. Therefore, the reasonable airflow organization is critical to the air distribution of the cold storage and must be carefully considered. In order to improve the uniformity of indoor air distribution, the study introduced the vertical wall attached ventilation which originated applied for indoor climate control of public buildings. To investigate the flow characteristics of the vertical wall attached ventilation, a three-dimensional SST k-ω solution model was established to study the distribution characteristics of the flow field and the cooling effect of the stored cargo. According to the practical array of the stored apples, the cargo area was regarded briefly as porous medium zone. In order to ensure the accuracy of the numerical calculation and the rationality of the mathematical model, grid independence verification and experimental verification were carried out. The accuracy of numerical calculation was studied by comparison with some accepted correlations and the rationality of the mathematical model was proved. The velocity distribution and temperature distribution of typical sections were monitored to illustrate the air flow pattern and temperature distribution characteristics under the vertical wall attached ventilation mode. Meanwhile, compared with the traditional air supply by cooling fan for direct blowing, it was clarified that the vertical wall attached ventilation could form a more uniformly temperature distribution and velocity distribution on the monitoring section and monitoring line. However, the air distribution of monitoring section and monitoring line could not fully reflect the overall temperature and velocity distribution inside the cold storage. Furthermore, the air distribution evaluation index was introduced and calculated in order to fully understand the temperature distribution characteristics of the studied cold storage room. First of all, in order to reflect the uniformity of air distribution, the non-uniformity coefficient of temperature and non-uniformity of velocity were introduced. According to the temperature and velocity values of 40 measuring points in each stack, the velocity non-uniformity coefficient and temperature non-uniformity coefficient were calculated under two air distribution modes. It was manifested that the vertical wall attached ventilation enabled non-uniformity coefficient of temperature and non-uniformity of velocity to decrease by 31% and 47%, respectively at the same air supply flow rate and temperature. Secondly, to evaluate the energy utilization of the air supply, the energy utilization efficiency of the two modes was calculated from monitoring air supply temperature, air return temperature and average temperature in the cargo area. It was indicated that the vertical wall attached ventilation made the energy utilization increase by 19% due to the more sufficient heat exchange between the air and cargo. Since the vertical wall attached ventilation can form a more uniform air distribution under a higher energy utilization rate, it can effectively improve indoor air distribution characteristics and well meet the storage requirements of fruits and vegetables [ABSTRACT FROM AUTHOR]

Under the condition of low ambient temperature in the cold region of the northern China, in the event that biogas project really wants to run normally, it needs to be heated by external heat source Choosing a reasonable heating system for the biogas engineering can not only make the heating system of biogas project more effective and reasonable, but also improve the utilization rate of energy. In addition, choosing a reasonable heating system for biogas engineering is truly the typical practical problem that must be solved to realize the low energy consumption and high output of biogas engineering. According to the application example of the heat pump heating system with the groundwater resource in the biogas project, an energy efficiency analysis model taking exergy efficiency, thermal efficiency, and energy level coefficients as the evaluation criterion for the biogas project heating system was established. Through the measured parameters of ground water source heat pump heating system, the results are obtained as the follows: The user system's exergy efficiency of the biogas project is 97.8%; The exergy efficiency of the groundwater source heat pump unit is 13.4%; The total exergy efficiency of the biogas project heating system is 13.1%; The total thermal efficiency of the heating system is 85.3%; the energy level coefficient of the user's heat consumption in the biogas project is 0.161; the energy level coefficient of the user's supply heat capacity is 0.164, as well as the energy level coefficient of the groundwater source heat pump unit is 0.567. The results indicated that the application of ground water source heat pump heating system in biogas engineering is practical and feasible. For users of low grade thermal energy of the biogas project, the exergy efficiency of using low temperature water for heating is relatively higher, and the process of energy use is quite scientific and reasonable. Moreover, the heat pump unit system can not only recover the low-grade heat energy from the groundwater, but also save the high quality electric energy in a feasible way, so that the effective utilization degree for the amount of energy used in the heating system can be very high, however, there still exists a difference in the quality of supply and demand between the heat source and the users, and the further improvement is needed in the use process of energy quality. It is suggested that the heating system of biogas engineering should adopt the heating mode matching the energy level and use the low grade heat source to heat the biogas project and evaluate the process of energy utilization synthetically. The above conclusion can be used as a reference for selecting a reasonable heating mode for biogas engineering in the future. [ABSTRACT FROM AUTHOR]

Penaeus vannamei is the agricultural product with high nutrition and delicious taste. It is becoming increasingly popular in both domestic and foreign consumers and has realized its health benefits to people. But Penaeus vannamei is a kind of product with seasonal characteristics for harvest and has short storage period due to the vulnerability to infection by the microbes and spoilages during storage. As a result, we may suffer a great loss in the end. So the drying of Penaeus vannamei is becoming an important processing. The drying of Penaeus vannamei is mainly the traditional natural drying at present. It has many disadvantages: products being spoilt due to wind, rain, and dust, great loss due to animals and birds, and deterioration due to decomposition by fungi and insect. Further, the process will spend much time, need a lot of labors and occupy a large area for spreading the produce out to dry. So the natural drying under the open sky can not guarantee the quality of final products. It is difficult to meet the needs of industrial production. The drying using coal-fire needs a lot of energy consumption and causes heavy pollution during the drying process. Whatever, the artificial mechanical drying such as vacuum freeze-drying and hot-air drying is energy intensive and expensive, and it will ultimately increase the product cost. Solar drying system can process Penaeus vannamei in clean and sanitary conditions. It takes little time and energy, occupies fewer areas and improves product quality. Solar drying is efficient and can protect the environment. To reduce the Penaeus vannamei drying energy consumption and improve the drying quality, the effects of solar drying temperature, drying capacity and airflow rate on the drying process were investigated in the laboratory. The results showed that the increase of the drying temperature and airflow rate and the reduction of the drying capacity could improve the drying rate and shorten the drying time. In the later stage of drying, the effect of drying parameters on water activity was significant. Different drying temperature had significant effect on the texture of Penaeus vannamei after rehydration. The change of color was not so obvious with different drying parameters but had a big difference with raw Penaeus vannamei. The 3 drying parameters had significant effect on dry shrinkage and rehydration ratio. With the increase of temperature and airflow rate, the energy consumption had a significant increase. Increasing the drying capacity could improve the utilization of the energy consumption. The drying time also had much relationship with the energy consumption. Through laboratory experiment, the drying temperature was 45-55 ℃, airflow rate was 6-8 m/s, and drying capacity was 3-4 kg. And the relationships between the drying temperature, drying capacity and airflow rate and energy consumption were analyzed through the response surface method. The quadratic regression models were established. The optimal parameters were as follows: solar drying temperature of 53.40 ℃, airflow rate of 7.43 m/s, and drying capacity of 3.65 kg. Based on the laboratory test, the pilot scale test of solar drying of Penaeus vannamei was carried out. It have dried 100 kg Penaeus vannamei (69.5 kg after Salt solution pre-cooking) , got 38.16 kg final product and took 4.5 hours. The total energy consumption of solar drying was 549 827.05 kJ, including effective use of solar energy 379 619.05 kJ and the electric power 47.28 kW·h. The energy consumption was 0.68 kW·h/kg.Compared with electric heating drying,it could save 1.51 kW·h/kg energy consumption. Compared with coal drying, it could make 0.75kg/kg CO2 emission reduction. The results will provide the basis for the industrial production of Penaeus vannamei solar drying. [ABSTRACT FROM AUTHOR]

With the use and depletion of fossil fuels, environmental pollution and energy crisis have become the biggest obstacles to the survival and development of human beings. Biomass energy utilization is an important way to solve this problem as it has wide source of raw material, and is clean and renewable. Biochar is an important form of biomass energy utilization, and it can not only change the waste straw into biomass energy, but also help reduce the greenhouse effect. The yield is a basic index in the study of pyrolysis technology; while the biochar is used as fuel, its calorific value is the factor directly reflecting the quality. These 2 indices are both necessary during the research. However, the existing research on the pyrolysis process of biochar is limited to all kinds of independent indices, and the optimal pyrolysis process is always not the same. In this paper, the advantages and disadvantages of pyrolysis process for biochar production were evaluated by the yield, calorific value and energy efficiency in order to design and optimize the process of carbonization of cotton stalk. The effects of the temperature, retention time and particle size on the yield and heating value of the biomass were studied; and the typical cotton stalk was taken as raw material to produce biochar under nitrogen gas atmosphere by slow pyrolysis. The results showed that: 1) The effects of pyrolysis temperature on the yield and heating value of the biomass were significant; the biochar yield was negatively correlated with heating value, and with the increase of the temperature, the yield of biochar decreased gradually, while the calorific value increased gradually. 2) The effect of retention time on the yield and heating value of the biochar was obvious, but it was not as obvious as the pyrolysis temperature; at the same time, it could be seen that the yield and heating value were negatively correlated, and with the increase of the retention time, the biochar yield decreased, while the calorific value increased. 3) Compared with the first 2 conditions, there was no significant change in the yield and heating value when the raw material particle size changed, which showed that the effects of particle size on the yield and calorific value were small. In addition, according to the general trend, we could still see a negative correlation between heating value and yield. Energy efficiency (ratio of total energy yield of biochar to energy yield of raw material) was proposed to coordinate the yield and calorific value, and the response surface analysis of the energy efficiency was carried out, from which the energy efficiency model was got. The results showed that when the temperature was 429℃, the retention time was 1.29 h, and the particle size was 0.32 mm, the predicted energy efficiency from the model reached the highest value, which was 78.95%. The model is validated by the experiment. The model can be used to guide the production of biochar with high energy efficiency, and provide the reference for energy efficient utilization. [ABSTRACT FROM AUTHOR]