The Research And Experimental Study For Evaporator Ice And Frost Detection Sensor

The various refrigeration equipment with automatic deicing and defrosting function usually adopts electrothermal technology to perform deicing and defrosting,but when deicing and defrosting is performed by timer timing control.This deicing and defrosting control method has a large waste in energy consumption.The main reason for this situation is that there is no evaporator ice and frost detection sensor to detect ice and frost directly in various refrigeration equipment.In order to meet this demand,this thesis is based on the principle of photoelectric detection,combined with the physical structure of the evaporator,puts forward two kinds of optical and photoelectric induction evaporator ice and frost detection sensor with certainly innovation and practical application value.And the sensors also was tested.In order to reduce the cost of sensor development as much as possible and meet the requirements of installation size,This thesis is based on the Fresnel reflection analysis of light propagation characteristics on the interface of different homogeneous media,and calculates a model of the intensity of the reflected light based on the incident angle under different states was deduced,and that is the principle of sensor detection.Based on the detection principle,Optical fiber sensor is designed to couple the light emitting tube and the receiving tube with the optical fiber respectively,and the transmitting and receiving fibers are arranged at both ends of the optical sensing window of the sensor in a direct way.The photoelectric inductive sensor,based on the development of the optical fiber sensor,uses the direct way to arrange the light emitting tube and the receiving tube directly At both ends of the sensor optical sensing window in order to reduce the influence of the attenuation of the optical fiber.The structure design,hardware circuit design and software program design of the sensor are introduced in detail.A complete detection system is constructed to complete the detection of ice and frost state information on the evaporator surface.In this thesis,a large number of tests were conducted during the research.Among them,the fiber-optic sensor is mainly a high-temperature impact verification test,a low-temperature influence verification test,a bending influence verification test,and a sensor feasibility verification test;the photoelectric inductive sensor is mainly a feasibility verification test.The experimental results prove that the two types of sensors are correct and feasible,and the comparison of two sensors shows that the photoelectric inductive sensor is less affected by other factors and is more suitable for practical application.Based on the above tests,two sets of deicing and defrosting basic comparison tests based on timer,sensor were carried out.According to the test's results,the intelligent deicing and defrosting control method based on the evaporator's ice and frost detection sensor is summarized.And according to the comparison of the energy consumption between the two groups of experiments,it is concluded that the deicing and defrosting energy consumption based on the evaporator's ice and frost detection sensor control mode is reduced much compared with the traditional timer-based control mode.It is further proved that the sensor developed in thesis paper has good performance.