Auto-cascade refrigeration system with single and double level coupling compression and control method

Abstract

The invention discloses an auto-cascade refrigeration system with single and dual level coupling compression. The auto-cascade refrigeration system with single and dual level coupling compression comprises a first-level compressor. An outlet of the first-level compressor is connected with an inlet of a first high-temperature-level condenser through a first solenoid valve. An outlet of the first-level compressor is connected with an inlet of a second-level compressor through a second solenoid valve. An outlet of the first high-temperature-level condenser is connected with an inlet of a fractional condenser. The fractional condenser is connected with a low-temperature-level condenser. The low-temperature-level condenser is connected with a second throttling valve. The second throttling valveis connected with an evaporator. The evaporator is connected with the first-level compressor. According to the auto-cascade refrigeration system with single and dual level coupling compression, the dual compressors are adopted for coupling work, single-compressor common two-level self-cascade refrigeration can be realized, two-level compression two-level self-cascade refrigeration can also be realized, and the refrigeration of two evaporation temperature zones can be realized. A high-boiling-point working medium is directly mixed with a working medium at the outlet of the first-level compressor after absorbing heat in the low-temperature-level condenser, and then enters the second-level compressor to lower the suction temperature of the second-level compressor, the exhaust temperature ofthe two-level compressor can be lowered then, and the system operation efficiency and the system operation stability are improved.

Description

technical field [0001] The invention relates to the field of low-temperature refrigeration, in particular to a self-cascading refrigeration system with single-stage and double-stage coupled compression and a control method. Background technique [0002] Low-temperature refrigeration technology is widely used in medical treatment, biological preservation, scientific research and other fields. It is of great significance to develop more reliable and efficient low-temperature refrigeration equipment. The method of mechanical refrigeration to obtain the temperature range below -40°C is usually multi-stage compression refrigeration cycle and cascade refrigeration. The cascade refrigeration cycle can be divided into ordinary cascade refrigeration cycle and single compressor automatic cascade refrigeration cycle. [0003] In the two-stage compression refrigeration cycle, the single working medium is compressed in two stages respectively, which can reduce the pressure ratio of each ...

AI Technical Summary

Problems solved by technology

[0003] In the two-stage compression refrigeration cycle, the single working medium is compressed in two stages respectively, which can reduce the pressure ratio of each stage and improve the reliability. However, due to the use of a single-component working medium, it is limited by the physical properties of the working medium. , such as: the limitation of evaporating pressure, critical temperature and freezing point, there are shortcomings such as too low suction temperature of the compressor, low gas transmission coefficient, etc., so that the system cannot operate normally

[0004] The traditional single-compressor two-stage self-cascading refrigeration system uses a binary non-azeotropic mixed working medium, and the evaporation temperature and condensation temperature can be operated at a temperature difference of 60 ° C to 80 ° C to achieve a lower evaporation temperature, but its pressure ratio is large. The life of the compressor is affected to a certain extent, and the operation stability needs to be improved. One system can only realize a relatively stable evaporation temperature zone, and cannot realize the adjustment of multiple evaporation temperature zones, which limits the application of the traditional single-compressor two-stage automatic cascade refrigeration system scope

Images