Investigation of defrosting control function based on model and sequence diagram

Abstract

Defrosting is an important controlled event of variable refrigerant flow air conditioning system (VRF AC). The whole course includes defrosting preparation phase, defrosting execution phase, defrosting end preparation phase and pump-down residual running phase. The defrosting control function can make a great influence on the performance of variable refrigerant flow air conditioning system, whose elements are composed of a certain controlled event, controlled components, executed conditions, controlled time, controlled courses and control logic. A sequence diagram is adopted to express the defrosting dynamic process and the control models of execution conditions on defrosting arrival, defrosting end and pump-down residual running end have been built. Thus, the defrosting control function has been formed based on the model and sequence diagram. The defrosting experiments demonstrate that the built model and sequence diagram can scientifically and accurately express the defrosting control function. Practical application: Defrosting is an important controlled event of variable refrigerant flow air conditioning system. It is difficult to describe the complex controlled course, which is composed of defrosting preparation phase, defrosting execution phase, defrosting end preparation phase and pump-down residual running phase. A sequence diagram can be adopted to express the defrosting dynamic process and the control models of executed conditions on defrosting arrival, defrosting end and pump-down residual running end have been built. Thus, the defrosting control function has been formed based on model and sequence diagram.