The Optimized Design And Thermal Performance Study For Fruit And Vegetable Soil Pit

In View of the traditional ventilation library autumn cool slowly to timely into the storage of fruit and poor insulation fruit and vegetable cold winter and spring temperature rebounded faster germination rot and so on three big fruit and vegetable industry problems,combined with the current agricultural production and rural economy in our country,through the structure optimization design,equipment improvement,and effect of performance test,developed with cooling humidification based on solar power,make full use of natural cold source function of saving energy and reducing consumption of fruit and vegetable soil pits,among them,the palisade structure heat preservation performance,fresh-keeping effect comprehensive indexes such as truss is superior to the traditional common cold storage.The results show that:(1)The pit structure optimization design.Adopt half underground jacketed structure,the use of the wall between the jacket ventilation,cold storage,water,good library uniform temperature;To determine the optimal width of kiln body,the largest surface area,and according to the storehouse of the concept of shape coefficient,to different pits,let the shape coefficient of the crypt fruits and vegetables made minimum limit;Thermal insulation material selection of cement hollow brick,benzene plate,rice husk,expanded perlite,etc.,wall thermal insulation layer,barrier layer and protective layer design,library and ceiling are multilayer insulation design;Installed in the fan,cooling,humidifying equipment,temperature,humidity sensors,has a good ventilation,cooling,humidification,heat preservation function,fully absorb the advantage of the library of ventilation and cold storage.(2)Fruit and vegetable crypt thermal performance study.Retaining structure,the total thermal resistance is 5.25 W/m2 ·K,the heat transfer coefficient K is 0.19 m2 ·K/W,its thermal resistance has reached the storehouse of the thermal insulation heat preservation standards R 3.3 W/m2 ·K or coefficient of thermal conductivity K 0.3 m2 ·K/W or less;Empty for 28 min,cooling time and outside temperature had no effect on its internal temperature,suggests new fruit and vegetable crypt has good heat preservation performance;(3)Temperature and humidity field phase distribution study,fruits,vegetables,crypt in 1 m height surface temperature and maximum temperature difference in 2 m height surface plus or minus 0.2 ? or less and uniform temperature distribution;Environment can maintain humidity is between 84%?89%,basic remains the same,the automatic control accuracy ± 2%;Compared with common cold storage should be regular defrost,fruits,vegetables,crypt is 83.6%less than the number of ordinary refrigerator evaporator frosting;Under natural ventilation,fruits,vegetables,crypt in average wind speed 0.084 m/s,under the mechanical ventilation(emissions after 5000 m/h),1.378 m/s,cooling,ventilation,the cellar in average wind speed 1.744 m/s,meet the demand of large fruits and vegetables at room temperature and low temperature storage.(4)Of fruits and vegetables in the crypt of air distribution test,found way of air distribution in the pit is the main factor affecting the air distribution;Fruit and vegetable crypt circulating air supply mode in three send mode which has the best distribution of air distribution,and have the best storage effect.(5)Common cold storage was studied,new fruit and vegetable crypt,the normal temperature of storehouse three different micro storehouse of potato storage effect.Compared the three tiny storehouse of potato in different storage period of the rolls,the change of the temperature,humidity and potato starch content,dry matter content and respiration intensity decay rate,germination rate and reducing sugar content in the physical and chemical indicators of change,the results show that the new fruit and vegetable soil pit of potato with better preservation effect.(6)Calculated fruits and vegetables crypt cost is relatively low in cost,and has more origin economic benefits,and pits using solar power to maintain equipment in operation,in north China region,power of 15 kW · h,maximum storage capacity of 43.2 kW · h,zero power consumption,can be used anniversary,saving energy and reducing consumption,reduce cost and efficiency.