Research And Development Of Refrigerating Unit And Its Control Device Using For Marine Refrigerated Container

In order to break the foreign company's monopoly on the core technology of marine refrigerated container,develop reefer container refrigeration unit and its control device with independent intellectual property rights,in this article,a new type of refrigeration unit and its control device were designed on the basis of comparative analysis on the reefer container products of current market.In the developed refrigeration unit,piston frequency conversion compressor and electronic expansion valve were selected to control refrigerant flow,inverter control of compressor combined with hot gas bypass regulating were used to realize capacity control;in the designed control device,The control device by means of industrial touch computer and multi-function data acquisition and control module were adopted to monitor and control the system's operation real-time,utilizing measure and control platform programmed by LabVIEW software,control strategy was performed according to the matched function mode of refrigeration system.Firstly,circulation process of refrigeration system was designed,component equipments of the system were chosen by the system load and the requirements of marine refrigerated container,and the refrigeration unit was built in accordance with standard specification.Then,electrical system was designed by the requirement of electrical control system and electrical equipments were selected properly,and then the control device was made standardly.Finally,the function modes of refrigeration unit including chilled model,frozen model,heating mode and defrost mode were determined according to the technical certification standards of marine refrigerated container,at the same time,in order to realize high accuracy temperature control,fuzzy adaptive PID control algorithm was adopted,and then all control software were programmed by LabVIEW software.Using the experimental rig,typical working tests including empty container refrigeration experiments,load step change experiments in chilled and frozen mode,and heating experiments were carried out,and the COP of the system was calculated.Experimental test results showed that the experimental rig could obtain the stable working state,rapid refrigerate(In chilled mode,the supply air temperature reduced from 29? to 0? within 16.4minutes,about 1.8? per minute;In frozen mode,the return air temperature reduced from 24? to-18? within 40.6minutes,about1.1? per minute),and high control precision(In chilled mode,control precision of supply air temperature was ±0.2?;In frozen mode,control precision of return air temperature was ±0.2?).In addition,the change of COP was small,which means that energy saving under all kind of working conditions can be achieved,and the developed refrigeration unit and control device were worthy of further development and utilization.