Negative-pressure liquid nitrogen subcooler and method for liquid nitrogen temperature reduction

Abstract

The invention relates to a negative-pressure liquid nitrogen subcooler and a method for liquid nitrogen temperature reduction. The negative-pressure liquid nitrogen subcooler is applied to the field of motor vacuum science and technology and comprises a liquid nitrogen conveying system, a subcooler system, a negative-pressure air exhaust system and a discharge system. Wherein the liquid nitrogen conveying system is used for providing liquid nitrogen for the subcooler system, the negative-pressure air exhaust system is provided with an air temperature type vaporizer which is used for reducing the pressure of the subcooler, gas and nitrogen are discharged by the discharge system, in the subcooler system, a pneumatic control valve is adjusted manually in a long-distance manner, so that liquid level of the liquid nitrogen in the subcooler is kept constant. The method comprises the following steps that: firstly, the liquid nitrogen is filled into a liquid nitrogen container, pressure is adjusted, the liquid nitrogen is filled into the subcooler, and the liquid level of the liquid nitrogen in the subcooler is kept constant; then, the negative-pressure air exhaust system is started, and the liquid nitrogen is cooled through a heat exchanger; at last, the liquid nitrogen is recycled and residual liquid is discharged. In the negative-pressure liquid nitrogen subcooler, defect that a constant-pressure liquid nitrogen subcooler only can provide the liquid nitrogen with the minimum temperature of 77 DEG C can be overcome, heat sink temperature can be further reduced, adjustable heat sink temperature between 70 DEG C and 77 DEG C can be achieved, equipment is simple, effect is good and cost is low.

Description

technical field [0001] The invention belongs to the field of engine vacuum science and technology. The invention relates to a subcooler device for further cooling low-temperature liquid nitrogen, in particular to a negative pressure liquid nitrogen subcooler device and a method for lowering the temperature of liquid nitrogen. Background technique [0002] The lower the heat sink temperature, the higher the pumping efficiency. The temperature of liquid nitrogen under normal pressure is 77K, and the liquid nitrogen heat sink is cooled to a minimum temperature of 77K, which cannot further reduce the temperature of the liquid nitrogen heat sink; the liquid helium heat sink is also firstly cooled by liquid nitrogen during the pre-cooling process. The minimum temperature of the liquid helium heat sink is 77K, and then converted to liquid helium refrigeration. The lower the conversion point temperature is, the less liquid helium is consumed when using liquid helium refrigeration, w...

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Problems solved by technology

[0004] The traditional subcooler is an atmospheric subcooler. The so-called atmospheric subcooler means that the pressure inside the subcooler container is normal pressure (one atmospheric pressure), and the lowest temperature of liquid nitrogen under normal pressure (one atmospheric pressure) is It is 77K, that is to say, the temperature of the liquid nitrogen inside the atmospheric pressure subcooler container is at least 77K, which cannot be lowered further. Lower the temperature below 77K, and the lower the temperature of the heat sink, the better the pumping effect, which can save the test cost. If the temperature of the liquid nitrogen inside the subcooler can be lowered, it can provide lower liquid nitrogen for the heat sink system.

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