Method of controlling refrigerant level of flooded evaporator

Abstract

The invention discloses a method of controlling the refrigerant level of a flooded evaporator. The ice water inlet temperature, the ice water output temperature, and the refrigerant evaporation pressure value of an evaporator are measured, the refrigerant evaporation pressure value of a condensor is measured, and the refrigerant output value of a compressor is measured, so that the output temperature error of the compressor and the arithmetic average temperature difference error of the evaporator are obtained. The openness of an electronic expansion valve is adjusted by the controller based on the output temperature error and the arithmetic average temperature difference error, so that the optimal refrigerant flow and level control are realized. Therefore, the heat exchange area of the evaporator is effectively displayed, the evaporation temparature is increased, and the part load efficiency of a chiller can be further improved.

Description

technical field [0001] The invention relates to a method for controlling the refrigerant level of a flooded evaporator, which provides a method for measuring the actual temperature difference between the inlet and outlet of ice water, the outlet temperature of the refrigerant, the evaporation pressure of the refrigerant, and the condensation pressure of the refrigerant to obtain an actual and Expected discharge temperature error value and an actual and expected arithmetic mean temperature difference error value, and then adjust the opening of the electronic expansion valve according to the error value to control the refrigerant liquid level of the evaporator, and effectively utilize the heat exchange area of ​​the evaporator, And can increase the evaporation temperature. Background technique [0002] In recent years, the technology of refrigeration and air conditioning has been approaching maturity. However, the basic concept of refrigeration or air conditioning is to use th...

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Problems solved by technology

[0005] The first liquid level sensor method uses a liquid level sensor with an electronic expansion valve as a method to control the liquid level of the refrigerant. Under the standard condition of full load, that is, the compressor is running at 100%, the liquid level sensor can be very precisely controlled. Refrigerant liquid level, but in the actual state, the compressor may only be partially loaded, because there is a huge difference between the refrigerant liquid level set by the liquid level sensor and the actual liquid level; moreover, the evaporation and boiling of the refrigerant It will also increase the overall variable, so that the refrigerant is not at the optimal liquid level, so the evaporator cannot effectively perform its best function, and the evaporation temperature of the refrigerant and the operating efficiency of the compressor cannot be improved; The liquid level analysis accuracy of the level sensor is poor, and the cost is high

[0006] The second way is to use the method of detecting the pressure of the condenser, which converts the detected pressure into a temperature, and adds a temperature difference to serve as a refrigerant discharge temperature, thereby controlling the refrigerant liquid level, but the height of the refrigerant liquid level Affected by the evaporation temperature of the refrigerant, the change in the discharge temperature of the refrigerant can be said to be very small. This change plus the error value of temperature detection makes it difficult to accurately control the refrigerant liquid level. In addition, external factors will also cause misjudgment, such as external The hot gas enters the evaporator, causing the illusion that the evaporation temperature and the discharge temperature are too high, which increases the difficulty of control. Moreover, the detection of the pressure of the condenser cannot be applied to the optimal condition of partial load or lower condensing pressure. liquid level requirements

[0007] The third method adopts gradual temperature control, which uses the fixed temperature difference between the ice water outlet temperature and the refrigerant evaporation temperature to achieve the purpose of refrigerant liquid level control, but it is still not suitable for partial load conditions. Liquid Level and Optimum Evaporation Temperature Conditions

[0008] To sum up the above, the existing three common refrigerant liquid level control methods with a single target set value have the disadvantages of high cost, poor liquid level analysis accuracy, and inability to effectively control partial load conditions to a better refrigerant liquid level. , so the existing refrigerant liquid level control method still has room for improvement

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