China Agricultural Machinery Testing Center

Beijing, China

China Agricultural Machinery Testing Center

Beijing, China

Time filter

Source Type

Liu C.,China Agricultural University | Ma C.,China Agricultural University | Wang P.,China Agricultural University | Zhao S.,China Agricultural University | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

The thermal insulation properties of solar greenhouse thick cover are affected by many factors, due to the complexity of heat transfer process which include conduction, convection and radiation. There have been some studies on the effects of the outdoor wind speed and infrared characteristic parameters of cover surfaceon the thermal insulation performance of thick cover. However, it is difficult to obtain accurate results due to the site conditions are not easy to control, and there are limited systematic studies on impact factors, which include heat preservation performance of greenhouse thick cover, using heat transfer theory. To master the effects of main influence factors on heat transfer coefficient of thick cover, we analyzed the relationship between surface emissivity of thermal insulation covers, thickness of thick cover, coefficients of insulation materials, wind speed of outside and the heat transfer coefficient of thermal insulation covers using heat transfer theoretical model on thermal thick cover. While the relationship between one factor and heat preservation performance of thick cover was being analyzed, other factors should be considered as constants to eliminate the impact of these factors. Thus the variation trend of relationship between single factor and heat transfer coefficient K can be gained. The results showed that the effect of up surface emissivity of thermal insulation covers on K value was more than 8.9%, and the effect of down surface emissivity of thermal insulation covers on K value was less than 4.5%, when there was fixed film under the thermal thick cover. When there was without fixed film, the effect about down surface emissivity of thermal insulation covers on K value would increase, but it was still lower than that of up surface emissivity on heat transfer coefficient. The increase in thickness and the decrease in conductivity coefficient of thermal thick cover would increase the heat transfer resistance substantially. So the K value would be decreased with thickness increasing or heat conductivity coefficient of thick cover materials reducing. It also showed that all the thermal insulation materials could meet the heat preservation performance requirements of horticultural cover, when the thickness was between 40 mm and 50 mm, based on the analysis of the relationship between K and thickness of thermal thick cover, conductivity coefficient of thermal insulation materials. K value of thermal thick cover was decreased with wind speed increasing (neglecting the heat loss of thick cover overlap joints) when emissivity of the upper surface was high and the heat transfer coefficient was low; K value of thermal thick cover was increased with wind speed increasing when emissivity of the upper surface was low and the heat transfer coefficient was high. An empirical formula on heat transfer coefficient was promoted based on the analysis of the relationship between influence factors and heat transfer coefficient. And the parameters in the formula were obtained by regression method. The empirical formula about K provides theoretical foundation for development and application of thermal thick cover. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.


Huang C.,China Agricultural University | Huang C.,Chinese Academy of Agricultural Sciences | Han L.,China Agricultural University | Liu X.,China Agricultural University | Ma L.,China Agricultural Machinery Testing Center
Energy Sources, Part A: Recovery, Utilization and Environmental Effects | Year: 2011

Rice straw can be used for biochemical conversion for energy production. The use of near infrared spectroscopy was explored to estimate the contents of cellulose, hemicellulose, and lignin in this study. A total of 172 samples from 17 provinces of China were collected and scanned using NIRSystem 6500 spectrophotometer. Different spectra pretreatments and regression methods were adopted to optimize the models. When evaluated on independent validations, the standard errors of validation and determination coefficient of validation were 1.49%, 1.59%, 0.65% and 0.82, 0.71, 0.78, respectively. It was concluded that near infrared spectroscopy can be used to roughly analyze the contents of cellulose and lignin, and can only distinguish high contents and low contents of hemicellulose in rice straw. Copyright © Taylor & Francis Group, LLC.


Chai L.,China Agricultural University | Ma C.,China Agricultural University | Zhang Y.,China Agricultural University | Wang M.,China Agricultural Machinery Testing Center | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2010

In order to study the feasibility of the application of ground source heat pump (GSHP) in greenhouses, experimental research on groundwater-style ground source heat pump system was carried out in greenhouse heating in Beijing. Experimental result showed that the coefficient of the system performance in greenhouse heating had reached 3.83 during the heating period of Oct.15, 2007-Mar.10, 2008, about 42% energy had been saved compare with conventional coal-fired hot water heating system, which its merits of energy-saving and greenhouse gases mitigating of the system were distinctive. The total electric consumption and the heating cost of the system was 0.15 kW·h/(m2·d) and 0.12 Yuan/(m2·d), respectively. The comparison among the heating systems of GSHP, natural gas, coal and light diesel oil were made, which the relative heating cost were 1.20, 1.31, 1.00 and 3.36, respectively, and the heating cost of ground source heat pump was higher than that of coal slightly, but was lower than that of natural gas and light diesel oil apparently.


Liu C.,China Agricultural University | Ma C.,China Agricultural University | Wang P.,China Agricultural University | Zhao S.,China Agricultural University | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

The quantity of nocturnal heat loss from conventional single skin greenhouse is high due to low thermal resistance of the single plastic materials. Therefore it is necessary for solar greenhouse that the thick covering material is covered on the single plastic covering material at night in China. There are lots of studies on heat transfer through thin cover of greenhouse, but limited reports about heat transfer through thick cover. However, the characteristics of heat transfer through thick covering materials of solar greenhouse are different from through thin covering. In order to master the heat transfer properties and thermal insulation characteristics of thick covering materials and its influencing factors, a model of heat transfer through greenhouse thick covering materials was developed based on the heat transfer theory in this paper. According to the theoretical model, a computer program was also designed and compiled to simulate the radiation, convection, conduction and other forms of heat transfer process of thick covering materials, and the quantity of heat transfer and the heat transfer coefficient were calculated. In the model there were some assumptions: the heat transfer process was regarded as a steady-state heat transfer; the sky was regarded as an infinite blackbody; the plant, ground, wall, roof inside the greenhouse were considered as one radiator which participated in radiation heat transfer with the under surface of thick cover, and the temperature, radiation emissivity and reflectivity of the radiator were the averages of theirs; the ground and the sky outside the greenhouse were also considered one radiator that participated in radiation heat transfer with the upper surface of thick cover; the surface of the thick cover, indoor ground, plant, wall, roof were regarded as grey body; the condensation heat transfer on the surface of the cover was neglected. The model used an analysis method on the effective radiation and the projection radiation of each surface to determine the quantity of radiation heat transfer between the upper surface and outdoor environment, the under surface and indoor environment. According to the principle of energy balance, the relationship between each part with various forms of heat transfer of thick cover was established. Based on the thermophysical characteristics, the construct parameters of greenhouse and the environment conditions etc., the heat transfer flux density and heat transfer coefficient of covering could be simulated and forecasted by this model. There was an apparatus to measure the overall transfer coefficient of covering materials, which was a static-hot box device. We used the device to test seven different combination types of thick covers of insulation materials. The results showed that the simulated heat transfer coefficient of thick covers was consistent with the values from experiments. This indicated that the theoretical model is highly accurate. The model can be used for quantitative analysis of heat transfer through thick covers and evaluation on the thermal insulation property. The theoretical model provides a method for the thick cover research and development as well as analysis of thermal environment about horticulture. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.


Ni J.,China Agricultural University | He J.,China Agricultural University | Li H.,China Agricultural University | Wang S.,China Agricultural Machinery Testing Center | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2012

The runoff study by using of simulated rainfall can significantly shorten the experiment period, and speed up the research process for the principles of rainwater infiltration and soil erosion. Currently, most rainfall simulators, which are bulky, complicated, expensive, and difficult to be adopted widely. A portable rainfall simulator consisted of the sprinkling system and the water supply system was designed to sovle above mentioned problems. This simulator employs a structure with single downward-oriented nozzles to realize a rainfall simulation, and it can artificially simulate different rainfall intensities as well as different rainfall durations by controlling the pressure of supplied water, and by changing the nozzle type. According to the rainfall properties test, this simulator realized simulated rainfall intensity ranging from 0 to 140 mm/h and rainfall uniformity over 80%. The raindrop diameter mainly distributed within the range 0.1-5.5 mm, and the raindrop speed at reaching ground ranging from 2 to 2.9 m/s was realized for different raindrop diameters. The test results were very similar with natural rainfall.The simulator can therefore effectively realize rainfall simulation.


Wang X.,China Agricultural Machinery Testing Center | Wang S.,China Agricultural Machinery Testing Center
Nongye Jixie Xuebao/Transactions of the Chinese Society of Agricultural Machinery | Year: 2010

At present, the standard system of agricultural mechanization in China faces some problems such as loose-standard, inadequate integrity, unbalanced development and so on. Based on the investigation and analysis of the existing agricultural mechanization standard system, this paper mainly considered the necessity of the agricultural mechanization standard system development. The 3-D framework consisting of field, product, type of standard of agricultural mechanization was designed by using analytic hierarchy process and 3-D structural method.


Yang M.,Chongqing University of Science and Technology | Zhu C.,West Gypsum Chongqing Co.LTD | Jin H.,China Agricultural Machinery Testing Center | Cai W.,Chongqing University of Science and Technology | Wang X.,Chongqing University of Science and Technology
Applied Mechanics and Materials | Year: 2012

Aiming at the complicated situation of artificial testing function materials, a set of automatic test system based on Agilent E4980A is developed. In the control software edited by Visual Basic 6.0, the test conditions (temperature, frequency, voltage, etc.) are pre-set, and the system automatically controls the temperature of the temperature control box through PID algorithm, achieving the real-time test voltage and frequency of Agilent E4980A. The card shows the readings on the test results of a plurality of functional materials at various stages of temperature conditions, automatically completing the storage and analysis of electrical parameters. The system is able to achieve the automatic control of the temperature control box and Agilent E4980A, presenting the comparative benefits including the function of this system being more comprehensive, more convenience in operation, and higher degree of automation advantages. It can be a good method and reference resource available for the development of such test system. © (2012) Trans Tech Publications, Switzerland.


Mengtao Y.,Chongqing University of Science and Technology | Hongwei J.,China Agricultural Machinery Testing Center | Xiaomei W.,Chongqing University of Science and Technology | Yonggang Y.,Chongqing University of Science and Technology
Applied Mechanics and Materials | Year: 2012

Based on the development practice of the pump performance test bed for the agricultural sprayer, a new program is proposed to cover the integrated mechanical structure of the pump performance test bed. Analysis was given to the various performance parameters of the pump test with regard to their testing methods, and specific methods of work performance test and inhalation performance test were also discussed to explore the test results. Finally, the issues that need to be focused were raised on the design and manufacture of pump performance test for the sprayer. © (2012) Trans Tech Publications, Switzerland.


Chen M.,Qingdao Agricultural University | Shi Y.,Qingdao Agricultural University | Qu G.,China Agricultural Machinery Testing Center
World Automation Congress Proceedings | Year: 2012

According to climatic and abundant solar radiation characteristics of Qingdao, the courtyard sunspace passive solar house was built. The sunspace temperature distribution and indoor ventilation quantity mathematical model was established based on its heat transfer theory. The courtyard sunspace temperature and auxiliary ventilation quantity were simulated, the simulated results were the same basically with experiment results, it showed that sunspace auxiliary ventilation mathematical model was correct, and the maximum ventilation quantity reached 160m3/h using courtyard sunspace auxiliary ventilation, which meet the demand of rural residential ventilation quantity. © 2012 TSI Press.


Chen M.,Qingdao Agricultural University | Shi Y.,Qingdao Agricultural University | Qu G.,China Agricultural Machinery Testing Center
World Automation Congress Proceedings | Year: 2012

According to rural building structure form of Qingdao, the courtyard sunspace passive solar house was built. A heat transfer mathematics model was established for courtyard sunspace passive solar house based on its working principle, and indoor temperature of courtyard sunspace passive solar house was simulated calculation, the indoor temperature of simulation result and experiment result were the same basically, it showed that mathematics model was correct and could provide theoretical basis to transform the courtyard sunspace in this area. © 2012 TSI Press.

Loading China Agricultural Machinery Testing Center collaborators
Loading China Agricultural Machinery Testing Center collaborators