Variable-flow single-working medium cascade refrigeration system with common condenser and common evaporator

Abstract

The invention discloses a variable-flow single-working medium cascade refrigeration system with a common condenser and a common evaporator. According to the invention, each refrigeration compressor unit is composed of a refrigeration compressor and four electromagnetic valves, wherein an exhaust end of the refrigeration compressor is connected with the corresponding first electromagnetic valve and the corresponding second electromagnetic valve; a suction end of each refrigeration compressor is connected with the corresponding third electromagnetic valve and the corresponding fourth electromagnetic valve; the first electromagnetic valves connected to the refrigeration compressors are connected in parallel and then are connected with an inlet in the condenser; the second electromagnetic valves connected to the refrigeration compressors are connected in parallel and then are connected with a condensation side inlet in a condensation evaporator; the third electromagnetic valves connected to the refrigeration compressors are connected in parallel and then are connected with an evaporation side outlet in the condensation evaporator; the fourth electromagnetic valves connected to the refrigeration compressors are connected in parallel and then are connected with an outlet in the evaporator; an outlet in the condenser is connected with an evaporation side inlet in the condensation evaporator through a high temperature level throttle valve; a condensation side outlet in the condensation evaporator is connected with an inlet in the evaporator through a low temperature level throttle valve. The cascade refrigeration system of the invention is formed by single working medium, and does not contain an expansion container and other devices, so that the structure is simple.

Description

technical field [0001] The invention relates to a refrigeration unit, more specifically, to a multi-head cascade refrigeration cycle system, which is used to improve the efficiency of the cascade refrigeration system and to regulate the refrigerant flow rate of the refrigeration system. Background technique [0002] The single-stage compression refrigeration system is not suitable for low-temperature refrigeration systems with a compression ratio (the ratio of the discharge pressure to the suction pressure) greater than 12 due to the limitation of the suction and discharge compression ratio of the compressor. In the prior art, when the compression ratio is greater than 12, a two-stage compression refrigeration system is usually used. The two-stage compression refrigeration unit can be driven by a motor, or it can be realized by combining multiple heads. However, the high and low pressure of these two methods are interoperable, and the oil return problem of the compressor is...

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Problems solved by technology

However, since the cryogenic working medium is in a supercritical state at room temperature, an expansion vessel is usually installed in

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