Liquid nitrogen vaporization temperature multi-stage adjusting control device for fruit and vegetable fresh keeping

Abstract

A liquid nitrogen vaporization temperature multi-stage adjusting control device for fruit and vegetable fresh keeping comprises a liquid nitrogen tank, a temperature sensor, a temperature control box,a liquid storage box, a liquid feeding pump, a liquid discharging pump and a control module; the liquid storage box is filled with a coolant, an outlet of the liquid storage box communicates with a coolant inlet of the temperature control box through the liquid feeding pump and a coolant outlet of the temperature control box communicates with an inlet of the liquid storage box through the liquiddischarging pump; the temperature control box is internally provided with at least two S-shaped vaporization tubes which are different in tube pass and used for conveying liquid nitrogen, an outlet ofthe liquid nitrogen tank is connected with tube inlets of the vaporization tubes, and tube outlets of the vaporization tubes are connected with an output tube; and a normally closed solenoid valve isarranged at the tube inlets of the vaporization tubes, the temperature sensor is arranged on the output tube, used for obtaining the temperature after liquid nitrogen vaporization and electrically connected with the input end of the control module, and the output end of the control module is electrically connected with the control ends of the normally closed solenoid valve, the liquid feeding pump and the liquid discharging pump. According to the liquid nitrogen vaporization temperature multi-stage adjusting control device, the temperature of the vaporized nitrogen is subjected to multi-stageadjusting control, and damage to products is avoided.

Description

technical field [0001] The invention relates to a multi-stage control device for liquid nitrogen vaporization temperature for fruit and vegetable preservation. Background technique [0002] At present, fruits and vegetables are generally transported in the way of controlled atmosphere fresh-keeping transportation, and the advantage of this transportation method is that it can prolong the fresh-keeping period and Guarantee the quality of fruits and vegetables. [0003] During the transportation of fruits and vegetables, the respiration of fruits and vegetables is suppressed by controlling the composition of the ambient gas in the box, thereby prolonging the preservation period of fruits and vegetables. At present, the existing controlled atmosphere methods are: spontaneous controlled atmosphere, two-phase variable controlled atmosphere, and decompression controlled atmosphere. These methods of air conditioning generally have problems such as low air conditioning efficiency ...

AI Technical Summary

Problems solved by technology

[0004] However, there will be the following problems in the liquid nitrogen filling atmosphere: on the one hand, the nitrogen is stored in the liquid nitrogen tank in the form of liquid, and the temperature of the stored liquid nitrogen is minus -196 ° C, when the liquid nitrogen is directly When entering the box, it will cause low temperature damage to the fruits and vegetables in the box

Liquid nitrogen is vaporized and heated by absorbing the heat of the air outside the vaporizer pipe. Since the temperature of the nitrogen after heating cannot be controlled, there is no guarantee that the nitrogen will not cause harm to the product.

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