| With the popularity of online shopping,fresh food e-commerce has also developed rapidly,and its rapid growth has created a new growth point for cold-chain logistics.However,terminal distribution of cold chain logistics appears a lot of problems in this new distribution mode.Adding ice packs to the commodity box is used for refrigeration in terminal distributioa This approach leads to lower quality of fresh products and increases the cost of secondary delivery when consumers are unable to get or delivery can't deliver on time.In addition,more and more people are asking for diversified distribution.In order to solve the problems of terminal distribution,the pick-up locker was born.However,the development of Chinese pick-up locker has just started,and it is not mature enough.At present,the municipal power grid is used for refrigeration in listed refrigerated lockers,they need to pay the electricity bills and not be energy-saving and environmentally friendly.Based on the above reasons,this paper designs a new kind of solar fruit pick-up locker and studies the performance of the new locker by means of theoretical analysis,experimental research and numerical simulation.The structure of solar fruit pick-up locker is designed according to user's research and the composition and principle of solar photovoltaic refrigeration system is analyzed.Selection methods are introduced for related refrigeration device and photovoltaic equipment.Taking Harbin as an example,the load of solar fruit pick-up locker is calculated,the refrigeration equipment and photovoltaic equipment are selected.The influences of different weathers and different seasons on the power supply characteristics are analyzed based on experimental method.Photovoltaic panel conversion efficiency is 11.1%in sunny weather,and cumulative power generation is 405.8Wh;conversion efficiency is 10.8%in cloudy weather,and power generation is 430.2Wh;conversion efficiency is 9.5%in rainy weather,and power generation is 114.5Wh.Among the four parameters of radiation intensity,ambient temperature,relative humidity,and wind speed,radiation intensity has the greatest impact on power generation.The analysis indicates that solar-powered refrigeration system is suitable in sunny,cloudy and rainy weathers.And the energy matching relations are different in the cases of different locker operating rates.Compared with summer and winter experiment data,the photovoltaic performances in summer are higher than those in winter.Since the required power of locker in winter is less than that in summer.solar fruit pick-up locker can achieve good seasonal match.The numerical simulation method is used to simulate the cooling process of a low temperature cold storage box of the solar fruit pick-up locker.When the evaporator is arranged in the rear wall of the box,the temperature distribution is not uniform and the average temperature is low.When the evaporator is arranged on the top of the box,the temperature distribution is uniform and the average temperature is higher.When the evaporators are part arranged in the rear and part arranged on the top of the box,the temperature distribution and average temperature between the above two cases.Increasing the insulation thickness can reduce the temperature of the locker.If the temperature is kept constant,increasing the thickness can reduce the energy consumption.It is not good for the system to open the door long time,the consumers and couriers should try to close within 20s.In addition,the accuracy of the numerical model is verified by experiment.In the final,the economy,energy saving and environmental protection of the solar fruit pick-up locker are analyzed.Its initial investment is high,annual operation cost is low,the total cost over the lifetime is higher than that of conventional fresh pick-up locker.But its energy conservation and environmental protection are better than the conventional one. |
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