Researches On The Characters Of Energy Saving In Marine Refrigerated Containers By Variable Frequency Control

Since 1970s, the energy problem has become one of the five biggest problems in the world. With the development of food industry and the increase in transported perishable commodity, the marine refrigerated container has been applied extensively, and then refrigeration devices consume too much energy. The marine refrigerated containers are of great mobility, and the changes of the outside air temperature, seawater temperature, the sun radiation intensity and the transported goods bring the changes in the latent and display heat load of refrigeration system. The traditional refrigeration system in containers adopts the mode of invariable revolution, and its system design is based on what can match the biggest heat load. So the refrigeration compressors and cooling fan motors have been chosen according to their biggest cool and heat burthen in working conditions. Actually, just in short time can refrigeration systems work in the biggest burthen. On Asian-European marine routes refrigeration systems are placed in 40-90% rating heat load for a bng period of time and the energy is wasted considerably. Therefore, energy saving of refrigeration devices invites more and more attention.This thesis analyzes the control principles of energy regulating ways in reefer units, compares the merits and demerits of these control methods in the outside working conditions of the changing burthen, and then puts forward the WVF, a entirely new energy saving regulative and control method. In addition, the thesis educes the heat response factors of container's round wall constructions by analyzing the dynamic heat transfer and adopting the method of heat response factors, and illustrates the refrigerated container's characteristics through an experiment on an empty refrigerated container.The main purpose of this thesis is to conduct a research on frequency conversion characteristics in reefer units through analyzing energy-consume, control method, and the technology of frequency conversion in refrigeration &air-conditioning. That is the focus of the research in this text.The change of the revolution of compressor by using the frequency conversion technology while the outside burthen alters, enables that refrigerant discharge changes alongwith the alteration of head load, and therefore refrigerating capacity will change respectively so that refrigeration system can match the variety in heat load. Meanwhile, after the revolution is reduced, the compressor energy-consume can be reduced and good results attained.The thesis analyzes the main character of reefer units fan motors when they run with frequency conversion control and the variable discharge character of evaporator. Suction gas pressure goes up as the compressor run at the lower speed in the lower burthen, and this is beneficial to lower systems energy-consume. When the system is controlled by WVF, the discharge change of the evaporator is not linear; the electronic expansion valve is adopted to regulate the system superheat degree, and the controlled object is parameter time varying, accordingly, the time varying controller should be adopted. Theory calculation of energy saving in fan motors shows that it is considerably effective in energy saving.This thesis analyzes all kinds of throttle components, points out the advantage of adapting EEV, and analyzes the start-up and the discharge characteristics of EEV, and dynamic response of refrigeration systems when the opening degree of EEV is changed, etc. EEV is placed into a tumoff position while the unit starts up, and after being kept for a period of time it is placed into a bigger position, after some more time it is put into a basic control. EEV should be selected for various refrigeration systems according to the thermal properties of refrigerants; the discharge coefficient of EEV is sensitive to the aperture and impulse quantity of EEV; When the EEV structure is made, the discharge coefficient goes up with the lowering of evaporation temperature or goes down with the hoisting of the condensation temperature...