| As an important link in the process of food production and circulation,food storage affects national food security directly.With social and economic development and people’s higher requirements for food security,quality and nutrition,the focus of addressing grain security is changing from total growth to both quantity and quality.Sichuan province belongs to the ecological zone of medium temperature and high humidity,with warm winter and hot summer and longer summer than winter,which is not conducive to grain storage,so the implementation of temperature-controlled grain storage is of practical significance.At present,temperature-controlled grain storage technology is developing rapidly,but there is not enough research on how to achieve low temperature storage or quasi-low temperature storage by different thermal insulation transformations in warehouse and application of various temperature-controlled technologies under the original warehouse and environmental condition in Sichuan.In this paper,by selecting six large size horizontal warehouses in Meishan Depot,Sichuan Province,respectively in the No.17 warehouse(the warehouse did not do thermal insulation transformation,wall mounted air-conditioning temperature control methods),No.18 warehouse(the warehouse did not do thermal insulation transformation,mechanical ventilation and wall mounted air-conditioning and other temperature control methods),No.19 warehouse(overhead PVC hollow panels on the roof,polyurethane aluminum panels pasted on the inner walls of the warehouse,mechanical ventilation,air duct machine and grain chiller and circulation in wall pipes and other temperature control methods),No.20 warehouse(overhead PVC hollow panels on the roof,wall mounted air-conditioning and circulation in wall pipes and other temperature control methods),No.21warehouse(the roof and walls of the warehouse are coated with aerogel paint,mechanical ventilation,air duct machine and internal circulation technique and other temperature control methods),No.22 warehouse(the roof and walls of the warehouse are coated with aerogel paint,mechanical ventilation,wall mounted air-conditioning and other temperature control methods)were tested for real warehouse storage,compare the change pattern of grain temperature and quality under different temperature-controlled grain storage processes in six demonstration warehouses,as well as the engineering cost and annual temperature-controlled grain storage cost of each silo,the main conclusions of this experiment are as follows:(1)No.17 and No.18 warehouses annual maximum warehouse temperature of 27.3 ℃,26.7 ℃,the whole warehouse maximum grain temperature are more than 25 ℃,did not achieve the annual quasi-low temperature grain storage;No.19,No.21,No.22 warehouses annual maximum warehouse temperature are not more than 23 ℃,the whole warehouse maximum grain temperature are not more than 25 ℃,the whole warehouse average grain temperature are not more than 20 ℃,three warehouses have achieved the annual quasi-low temperature grain storage;No.20 warehouse maximum warehouse temperature in 23 ℃ or so,the highest grain temperature of the whole warehouse in August exceeded 25 ℃,the average grain temperature of the whole warehouse exceeded 20 ℃,the summer period did not achieve the quasi-low temperature grain storage,the reason is that the No.20 warehouse grain is new in May 2022,grain base grain temperature is higher,but the No.20 warehouse temperature in the high-temperature season fell significantly,the temperature of the warehouse in August was 9.7°C lower than the outside temperature,and the temperature control effect was remarkable.(2)The grain quality indexes of No.17 warehouse～No.22 warehouse did not change much after temperature-controlled storage throughout the year,well controlled the increase of fatty acid value,delayed the grain quality aging,controlled the quality indexes within the range of the desirable storage standard,and ensured food security through the summer.Warehouses that realize quasi-low temperature grain storage can better inhibit the rise of fatty acid value,the fatty acid value rise in No.19 warehouse and No.22 warehouse is 1.0mg KOH/100g～2.5 mg KOH/100 g,and the fatty acid value rise in No.17 warehouse,No.18 warehouse and No.20 warehouse is 3.5 mg KOH/100g～5.0 mg KOH/100 g.The corn in No.21 warehouse was stored for a long time and the temperature control was not performed during the removal of the grain from the warehouse in September 2022,so the fatty acid value rose up to 6.9 mg KOH/100 g.(3)The total project cost of No.17 warehouse～No.22 warehouse is 24000 yuan,24000 yuan,499000 yuan,247000 yuan,521000 yuan,399000 yuan respectively,the construction cost per ton of grain is 6.7 yuan/ton,6.9 yuan/ton,182.2 yuan/ton,69.4 yuan/ton,147.2 yuan/ton,145.7 yuan/ton,respectively.The project cost of No.19 warehouse and No.21 warehouse,where the roof and the walls are heat insulation renovated and the air duct machines for grain are installed,is relatively high,the No.22 warehouse with heat insulation transformation of the warehouse roof and walls and No.21 warehouse with heat insulation transformation of the warehouse roof only,wall mounted air conditioners are installed in both warehouses,and their project cost is in the middle,No.17 warehouse and No.18 warehouse,where the roof and walls of the warehouse are not modified for heat insulation and only wall mounted air conditioners are installed,have the lowest project cost.(4)The annual temperature-controlled grain storage cost of No.17～No.22 warehouse is5100 yuan,5419 yuan,12889 yuan,8821 yuan,15041 yuan and 5236 yuan,respectively,and the cost per ton of grain is 1.4 yuan/ton,1.6 yuan/ton,4.7 yuan/ton,2.5 yuan/ton,4.3yuan/ton and 1.9 yuan/ton,respectively.The reason for the relatively high cost of temperature-controlled grain storage in No.19 warehouse and No.21 warehouse throughout the year is that the electricity cost generated by the temperature control of the air duct machines in the warehouses is higher,and it includes the cost of the grain chiller in No.19 warehouse and the cost of grain was shipped out of the No.21 warehouse,No.20 warehouse,No.17 warehouse,No.18 warehouse and No.22 warehouse all use wall mounted air conditioners to control temperature,but No.20 warehouse produced more electricity costs in May 2022 when corn entered the grain warehouse,so the annual cost of temperature-controlled grain storage was second only to No.19 warehouse and No.21 warehouse,while No.17 warehouse,No.18 warehouse and No.22 warehouse have the lowest annual cost of temperature-controlled grain storage.To sum up,on the basis of the thermal insulation transformation of the warehouse,the No.19 warehouse and No.21 warehouse with mechanical ventilation in autumn and winter,and the No.19 warehouse and No.21 warehouse with air-conditioning temperature control mainly combined with other temperature control technologies for comprehensive temperature control in summer or the No.22 warehouse with air-conditioning temperature control alone can realize quasi-low temperature grain storage,and more effectively inhibit the increase of fatty acid value of grain and delay the aging of grain quality,and on the basis of quasi-low temperature grain storage,the No.22 warehouse has the lowest construction cost per ton of grain and the lowest cost per ton of grain for annual temperature control grain storage and the best economy. |
