Papers by Author: Jing Xie

Abstract: The effects of modified atmosphere packaging (MAP: 80%CO₂/20%O₂) and chitosan (CS: 10.0g/L) on the shelf-life of pomfret (Pampus argenteus) fillets during chilled storage were studied. Quality assessment was based on biochemical (total viable counts (TVC), total volatile base nitrogen (TVB-N), tri-methylamine (TMA-N), K-value, pH value) and sensory analysis indices determination. The results showed that MAP and CS could keep the sensory quality of Pampus argenteus, delay its deteriorating speeds and slow down the increase of K-value effectively. Compared with the control samples, the shelf-life of pomfret samples in MAP and CS stored at 4±1°C were 10, 12d respectively.

Abstract: Efficient nitrite adsorbent materials made from corncobs through physical and chemical modification were used to adsorb nutrite in seawater. In this experiment, the effect of time and modification on corncobs adsorption capacity was studied. It shows that the removal ratio for nutrite presented an increasing tendency over time and reached the highest after 270 minutes, the removal ratio of modified corncobs reached 52.1%, which improved 10% compared with unmodified corncobs. Besides, through contrastive experiment with some other nitrite adsorbent materials, modified corncobs are proved to have the highest removal ratio for nutrite.

Abstract: In order to realize the optimization of insulation performance of air curtain used in the cold store. The unsteady state simulation of the flow field of air curtain used in the cold store was studied by the CFD software to predict variation of the flow field in the cold store after door and air curtain were opened and the time of the flow field of the cold store arriving to be uniform. The experimental verification was also taken. The simulation results reflected that the temperature of the upper area closing to the door increased first and then decreased, then increased. The intrusive hot air destroyed the original uniform air flow distribution and caused the formation of the swirling eddy. When the whole flow field of the cold store was uniform, the swirling eddy disappeared. The re-circulation moved forward the lower left side of the cold store, which was caused by the intrusive hot air. Local mesh refinement could improve the simulation accuracy and be useful to analyse the flow characteristic of the air curtain. The times of the flow field in the cold store arriving to be uniform predicted by the numerical simulation and experiment after door and air curtain being opened were 5 min and 6 min, respectively. This study will provide useful references for optimization of insulation performance of air curtain.

Abstract: Air curtains are commonly used to cut off air flow between the cold store and hot environment, and reduce heat and mass transfer in order to maintain the low temperature in the cold store. CFD can be used to predict operation rule of air curtain used in the cold store intuitively and modelling is the most important part of numerical simulation of air curtain used in the cold store. In this study, different numerical models including standardmodel (with and without boussinesq approximation) and RSM (with and without boussinesq approximation) were used to simulate the temperature field and air flow field in the cold store and operation rule of air curtain used in the cold store after air curtain opened for 60s. Meanwhile, the actual operation of air curtain used in the cold store was tested and the simulation values were compared with the experimental values. The results showed that the velocity of the central mainstream decayed slowly, but the velocity of both sides of air curtain decayed fast. The optimal model used to predict the temperature field and air flow field in the cold store and operation rule of air curtain used in the cold store was standardmodel with boussinesq approximation, the relative error was within 20%. The optimal model can be used to predict the temperature field and air flow field in the cold store during different times in the future research.

Abstract: Chinese small cabbage (Brassica rapa L.Chinensis Group.), is one of Shanghai special vegetables, whose storage qualities were rarely studied by domestic researchers yet. Hence for, physical and chemical indexes of Chinese small cabbage ( harvested in Lingang new city, Shanghai) stored at temperature 2 °C, 6 °C, 10 °C, 15°Cwere determined in this study. It was shown that as temperature lower, the degradation rate of reduced ascorbic acid and chlorophyll were smaller, respiratory rate and weight loss rate rate were lower. Taking into account the quality of Chinese small cabbage in the whole experiment process stored at a single temperature concerned, degradation rate of nutrients , such as, reduced ascorbic acid and chlorophyll were more and more smaller. Due to environmental stress effect, total phenolic content was increased at first days, and then decreased as antioxidant capacity reducing. On the other hand, respiratory rate increased along with blade decay which was caused by injury breathing and moisture loss leading enhancement of hydrolase activity. Changes of chrome parameters like L*, a*, b*,BI, h*and E had positive correlation with physiological quality. Overall, low temperature inhibits the physiological activities of the Chinese small cabbage and prolongs the shelf life, but chilling injury should be paid attention to.

Abstract: 120 crucian carp were divided into 4 groups. Each group included two repeats with each of 15 crucian carp, and was fed with feedstuff mixed probiotics concentrations at 0.0%, 0.2%, 0.4%, and 0.6%. The figure index and viscera index were measured, and the nutrient compositions were analyzed after 32 feeding days. As a result, the best probiotics concentration is 0.4% on the increase of the weight gain and the nutrient compositions.

Abstract: In this article, the application of Computational Fluid Dynamics (CFD) technology in the field of Heating Ventilation & Air Condition was introduced, and the research progress in optimizing the simulation of air-conditioned room was summarized. Some domestic and foreign studies on air conditioning operation and energy saving were illustrated about the effects of different installation locations, blow angles and air supply modes, which would provide a theoretical basis and scientific guidance for air-conditioning systems to optimize the design. Based on previous results, the development of further research on CFD in the simulation of air-conditioning in future was analyzed.

Abstract: Vacuum pre-cooling technique was used as a rapid cooling method for leafy vegetables such as lettuce, spinach and so on. Experiments were carried out to investigate the effect of vacuum pre-cooling on physiological activities during cold storage. The results revealed that the increase in weight loss and membrane permeability was inhibited, and the sensory quality was improved. Meanwhile, the decompositions of chlorophyll and soluble solids were delayed. Taking all these into account vacuum pre-cooling treatment can significantly extend the shelf life of spinach.

Abstract: In the evaporative condenser, the shape and structure of the nozzle determines the spraying effect, which affects the overall heat transfer performance of the evaporative condenser. Due to the constraints of its structure, spraying test is difficult in evaporative condenser operation process. The performance of the two types of nozzle spray is simulated by CFD numerical calculation software, using the two-dimensional modeling. The results show that the two-tier shunt platform nozzle sprays more uniformly, the movement of airflow around is relative more regular, the performance of spraying water is more stable. The reference is provided to select the optimal structure of the nozzle under certain conditions.

Abstract: The sales volume of vertical air conditioner in China mainland has developed rapidly. The researches in the field to the operation of vertical air conditioner are lacked since it is hardly to analyze different kinds of operating condition. Computational Fluid Dynamics (CFD) has been applied in engineering with the advance of the computer science and technology. In this article, both temperature and air flow distributions were analyzed to a meeting room which putted a vertical air conditioner. The model was used and the equations for numerical simulation (e.g. energy, residual, continuity, etc) were chosen as second order to get the higher accuracy. The results to simulation were showed reasonable and could offer a reference to the practical.