Negative-pressure liquid nitrogen subcooler and method thereof for reducing liquid nitrogen temperature

Abstract

The invention provides a negative-pressure liquid nitrogen subcooler and a method therefore for reducing liquid nitrogen temperature. The negative-pressure liquid nitrogen subcooler comprises a liquid nitrogen conveying system, a subcooler system, a negative-pressure air exhausting system and a discharging system, wherein the liquid nitrogen conveying system is used for supplying liquid nitrogen to the subcooler system; the negative-pressure air exhausting system is used for reducing pressure for the subcooler; and the discharging system is used for discharging gasified nitrogen. In the negative-pressure liquid nitrogen subcooler, an electric heater is adopted to raise the temperature of gaseous nitrogen to 20-30 DEG C, so that the subcooler is not limited to the weathers; a liquid level sensor is adopted to automatically regulating the opening of a pneumatic regulating valve, so that the height of the liquid level is maintained. The method comprises the steps of: firstly, injecting the liquid nitrogen for a liquid nitrogen container and regulating pressure; then injecting the liquid nitrogen for the subcooler, wherein the height of the liquid level of the liquid nitrogen in the subcooler is kept constant; then starting the negative-pressure air exhausting system, and cooling the liquid nitrogen through a heat exchanger; and finally, recovering the liquid nitrogen and discharging the liquid nitrogen. According to the invention, the temperature of a heat sink can be further reduced, the temperature of the heat sink is regulatable within a range of 70-77k, and the advantages of simple equipment, good effect and low operating cost are achieved.

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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