Study On The Performance For Storage Equipment Used Seasonal Clean Energy In Plant Areas

At present,people are demanding higher quality of life,especially food quality.At the same time,they are faced with the problem of high energy consumption of cold chain facilities for fruit and vegetables storage.Because of the shortage of energy worldwide and the high cost of construction and operation of modern cold chain facilities,the imbalance between reality and people's high-quality living requirements is caused.Ventilated soil pit is a low-cost,low-energy consumption and high-benefit storage facility,which is an ideal supplement to the shortage of modern cold chain facilities at the current stage in China.However,due to the application of modern technology in traditional ventilated soil pit is relatively few,the standard of facilities is low,and the supporting equipment is insufficient,which led to not meeting the requirements of stability and accuracy of storage environment for fruits and vegetables.The temperature and humidity environment in the ventilated soil pit,as well as the reasonable and stable distribution of airflow field,have a direct impact on the storage effect of goods in the ventilated soil pit.Aiming at the rationality and stability of airflow field in ventilated soil pit,this paper optimizes a set of ventilation and goods stacking schemes.Taking a semi-underground ventilated soil pit as the research object,a reasonable three-dimensional geometric model and a suitable number of grid models are established on the basis of investigation.On the basis of hypothetical conditions,using computational fluid dynamics technology of single flow field in a ventilated soil pit are simulated and analyzed under several conditions,the data was carried out through visual process and then to compare with the same cases,including:(1)Air distribution simulation under three modes of direct forced air supply,forced air supply in bends and two-way forced air supply is carried out.Under different air supply modes,the flow field in the central reflux area of the ventilated soil pit is relatively stable,which has the same characteristics of “small in the middle,big around”.However,in the near wall region,with the different air supply modes,the size of velocity gradient and the degree of turbulence of air flow are obviously different.After adding bend and two-way duct,the phenomenon of reflux of adherent surface and airflow vortex is more obvious.From the point of view of stability of velocity field,direct forced air supply is more suitable for this type of ventilated soil pit.(2)On the basis of direct forced air supply mode,the air distribution at 2 m/s,3 m/s,4 m/s and 5 m/s of air supply speed is simulated.With the increase of air supply speed,the area of airflow vortex in the goods storage area increases gradually.When the velocity increases to 5 m/s,the area with airflow speed greater than 0.5m/s occupies about 3/4 of the total volume,and for fruit and vegetable storage,the largerthe area is,the smaller the area suitable for storing goods will be.According to the design specifications,for this type of ventilated soil pit,it is recommended to select 2 m/s air supply speed,and suitable for goods placement in the central area of 1.92×1.52×1.87 m.(3)Under the condition of direct forced air supply and 2 m/s air supply speed,the air distribution is simulated under three stacking modes,i.e.one stack,two longitudinal stacks and two transverse stacks.The stacking modes of the two stacking modes have better liquidity than that of one stack.The difference of surface velocity gradient under three stacking modes is 0.62m/s,0.47m/s and 0.37m/s respectively.In view of the air vertex phenomenon of two transverse stacks stacking form is less and the gradient of goods surface velocity is smaller,it is suggested that two transverse stacks stacking form be selected in the effective area of goods storage for this type of ventilated soil pit.The traditional ventilated soil pit is mainly based on the planting experience of managers to manually adjust the temperature,humidity and gas ventilation parameters,therefore it has the problems of long reaction time,untimely handling and high labor costs.Based on the structure of ventilated soil pit,this system establishes a comprehensive control mode with temperature control as the main part and humidity control as the auxiliary part.The proposed system uses PLC technology,touch screen technology and remote data interaction technology to realize three major functions,namely,the automatic humidification/dehumidification,automatic ventilation and automatic cooling with two working modes,the automatic and manual mode.It can not only realize real-time accurate control of storage environment factors,but also effectively reduce the difficulties of managers' operation by combining local and remote visual control.The lower computer of the system collects the setting parameters of the ventilation soil pit and the external environment parameters in real time,automatically start or stop the actuator according to the set conditions.The upper computer of the system updates and displays the uploaded data in real time,and it can changes and sets the control parameters and actuator status.Through the test of the system's artificial emergency control effect and the test of the stabilities of temperature field and humidity field under the automatic control mode,the system is of important value both on theoretical and practical and it can effectively improve the efficiency of management and the operational conditions of personnel,achieve good storage effect,prolong the fresh-keeping period,improve the added value of fruits and vegetables,and promote the industrial development of fruit and vegetable preservation.