Fresh air unit and its control system

Abstract

The invention provides a fresh air unit control system, which includes an internal heat exchanger and an external heat exchanger connected by pipelines, the internal heat exchanger includes a plurality of sub-heat exchangers arranged in parallel, and a plurality of sub-heat exchangers The refrigeration output branch pipelines are connected to the refrigeration output main pipeline, and at least one refrigeration output branch pipeline is provided with a solenoid valve and a one-way valve arranged along the refrigeration direction in parallel. The heat exchanger of the internal unit is composed of multiple sub-heat exchangers connected in parallel. The check valve enables the heat exchanger of the fresh air unit to participate in the refrigeration cycle when the fresh air unit is cooling at low temperature, ensuring sufficient heat exchange area and preventing the compressor from returning liquid and overheating. Hand in frosting. Adjust the opening and closing of the heat exchanger of the internal unit through the solenoid valve, and control the heat exchange opening area of ​​the heat exchanger of the internal unit, so that when the system is heating at low temperature, the heat exchanger of the internal unit can be used as a condenser to close part of the heat exchange circuit, reducing the Condensation effect, increase the condensation pressure, so that the compression ratio of the compressor can be established normally, thus ensuring the safety of the fresh air fan system.

Description

technical field [0001] The invention relates to the technical field of refrigeration system control, and more specifically, relates to a fresh air unit and its control system. Background technique [0002] Industrial and commercial places have higher and higher requirements on fresh air cleanliness, especially in technological places, more and more attention is paid to fresh air pretreatment, so the demand for fresh air units is increasing. The fresh air unit is a kind of air conditioning equipment that provides fresh air. For the air-cooled cold wind fresh air unit, the indoor return air temperature is the same as the outdoor temperature. However, when the fresh air unit operates in low temperature or high temperature conditions, the unit It is prone to problems such as system liquid return and excessive exhaust pressure, which seriously affect the normal operation of the equipment. [0003] When the system is operating at low temperature for cooling or heating, the air in...

AI Technical Summary

Problems solved by technology

As a result, the system pressure difference cannot be established, and the compression ratio of the compressor is very low, exceeding the minimum compression ratio allowed by the compressor, which seriously affects the normal operation of the compressor.

[0005] When the system is running at maximum cooling, the temperature of the indoor and outdoor heat transfer air is very high, so the heat exchange temperature difference on the condensing side is very small, and the condensation effect is very weak, resulting in high condensing pressure and condensing temperature. At this time, the exhaust of the compressor The pressure and discharge temperature are both high, which will exceed the maximum allowable working pressure and working temperature of the compressor and cause the compressor to overload

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