Variable Capacity Modular Combined Refrigerating Installation by Frequency Conversion

Abstract

A variable capacity modular combined refrigerating installation, which has several modular refrigerating units. Each modular unit has a refrigerating circle, which includes a refrigerating compressor set (1), an evaporator (4) and a condenser (10). A flow control valve (6) is mounted at the refrigerating medium inlet / outlet port of the evaporator (4); and / or a flow control valve (11) is mounted at the inlet / outlet port of the condenser (10). The refrigerating compressor set (1) comprises an adjustable frequency motor (1A) and a compressor (1B) with magnetic suspend bearings. Each modular unit is also provided with an inlet pressure sensor (26) and / or discharge pressure sensor (27). The installation provided with a refrigerating water temperature sensor (19), a sensor (20) for pressure difference between supply and return at the installation side and a sensor (21) for pressure difference between supply and return at the load side; and a sensor (22) for pressure difference between supply and return at the installation side. The present invention can decrease the power consumption of the air conditioning system and provide a convenient and improved control.

Description

TECHNICAL FIELD[0001]The present invention relates to a refrigerating installation, especially to a variable capacity modular combined refrigerating installation by frequency conversion.BACKGROUND ART[0002]The modular combined refrigerating installations have been widely used for design and application of the refrigerating water installation of air conditioning system. According to the requirement of installation load of the building, the modular combined refrigerating water installation is composed of multiple standard refrigerating modular units, and the installation capacity of the system may be increase or decrease at any time, so it can be used flexibly. Also, because each refrigerating modular unit is a complete refrigerating system, the number of the running modular units may be increased or decreased under the control of the master controller according to the need of the system load. So not only the outlet of the installation highly correspond with the need of the system, bu...

AI Technical Summary

Benefits of technology

[0003]The purpose of the invention is to provide a variable capacity modular combined refrigerating installation by frequency conversion. It is improved on the basis of the prior modular refrigerating installation, to decrease power consumption and improve control level.

[0014]There is an economizer in each modular unit. The liquid cryogen exited from the condenser is divided into two parts, one part super cools the other part after being throttled and then evaporates. Since the cryogen after the evaporation has a pressure higher than the outlet pressure of the cryogen of evaporator, it enters into the intermediate pressure suction port of the condenser 1B. This economizer cycle can increase the refrigerating capacity and the refrigerating efficiency of a refrigerating unit.

[0018]The present invention is based on the application of a new type of compressor set and heat exchanger. The new type of refrigerating compressor set can control the opening ratio of the refrigerating / cooling medium valve devices according to the working parameters provided by the sensors, or change the working frequency of the input power supply according to the working parameters provided by the sensors, so as to regulate the operating speed of the motor to adjust the output refrigerating capacity of the refrigerating installation. This compressor set is different from the traditional compressor set in that it adopts the magnetic suspension bearings, so it does not need the traditional lubricating oil and the corresponding circulating system and cooling system, and it does not pollute the heat exchanger and affect the efficiency of the heat exchange due to the existence of the lubricating oil. The oil-free compressor facilitates the use of full liquid evaporator. Furthermore, the compressor set integrates a control means of digital circuit, and can monitor and adjust the operating condition of the compressor in real time and allow each refrigerating modular unit to work in balance without depending on the outside control system. The heat exchanger used in the invention is a plate heat exchanger having the full liquid evaporation function. In all kinds of evaporators, the full liquid evaporation is a heat exchange process of high efficiency, in which the refrigerating medium channel is immersed in the liquid cryogen, so that the heat exchange can be carried out under a very little temperature difference. The new type of heat exchanger of the invention combines the operating principle of full liquid evaporator and the compact structure of plate heat exchanger, and incorporates with the economizer, thereby obtaining a heat exchange device with higher efficiency.

[0019]In general, the present invention apply the abovementioned new techniques and control the circulation flow of the refrigerating and cooling medium by combining the viable frequency control technique, therefore, it not only can change the refrigerating output of the refrigerating modular unit by controlling the working frequency of the input power, but also can make the working flow of the refrigerating and cooling medium to be consistent with the refrigerating capacity, so that reduce the running power of the water pump or the blower fan when the compressor set or the refrigerating installation is running with low load, and finally decrease the power consumption of the air conditioning system and improve the control level to make the control more convenient.

Problems solved by technology

Thus the running efficiency will not be decreased due to the decrease of the load, thereby decreasing the running cost of the installation.

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