Ultralow-temperature auto-cascade type refrigerating device and refrigerating method

Abstract

The invention provides an ultralow-temperature auto-cascade type refrigerating device and a refrigerating method. The refrigerating device comprises a pre-cooling unit and a multi-element refrigerant circulating unit connected with the pre-cooling unit through a pre-cooling heat exchanger. A main compressor, a main condenser, a medium passage I B of the pre-cooling heat exchanger, a regenerator, a first gas-liquid separator, a high-temperature medium flow passage I A of a first secondary heat exchanger, a second gas-liquid separator, a high-temperature medium flow passage I A of a second secondary heat exchanger, a main throttling element, a medium passage II A of a main evaporator, a low-temperature medium flow passage II B of the second secondary heat exchanger, a low-temperature medium flow passage I B of the first secondary heat exchanger and a medium passage III B of the regenerator are connected in sequence. A pressure release valve, a liquid storage tank and a pressure release bypass of a second throttling element are arranged between the outlet end of a medium passage III A and the inlet end of the medium passage III B and are connected in sequence. The invention further provides a refrigerating method using the refrigerating device. The refrigerating device and the refrigerating method have the advantages that starting time is short, a target temperature can be rapidly reached, and operation is safe and saves energy.

Description

technical field [0001] The invention belongs to the technical field of deep refrigeration, and in particular relates to an ultra-low temperature self-cascading refrigeration device and a refrigeration method. Background technique [0002] Ultra-low temperature refrigeration technology has many applications, such as liquefaction of natural gas and biogas, simulation of space environment, food processing and preservation, scientific research, etc. [0003] Utilizing the principle of vapor compression refrigeration to achieve ultra-low temperature mainly includes cascade refrigeration, mixed refrigerant refrigeration and expander refrigeration. The cascade refrigeration process has the advantages of independent refrigeration sub-circulation systems, less mutual influence, stable operation, strong adaptability, simple design and calculation, and low energy consumption. However, the average temperature difference between cold and hot media is large, and the process is complicated...

AI Technical Summary

Problems solved by technology

ZL03121465.7 adopts the main throttling element, auxiliary throttling element and bypass throttling element to control the system flow and try to ensure that the system pressure will not be too high; however, the limitation of the opening change of the throttling element makes the rapid flashing The vaporized refrigerant gas is difficult to quickly balance to the low-pressure side. Even if all the throttling elements are fully opened, there is still the possibility of high-pressure tube burst because the volume of the system containing the refrigerant gas does not increase.

Rui Shengjun et al. (Pressure characteristics of automatic cascade refrigeration system, Acta Chemical Industry, 2012, 63(12): 176-180) stabilized and reduced the pressure on the high pressure side through high and low pressure bypass pipes and expansion vessels, and the low temperature, The system pressure when the medium-temperature refrigerant exists in gaseous form; but in the start-up phase, when the bypass solenoid valve is opened, a large amount of refrigerant enters the expansion vessel and returns directly to the compressor after throttling, so that the refrigerant entering the condenser The quality is greatly reduced, which seriously affects the cooling effect of the system and delays the time to reach the target temperature

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