Determination criterion of defrosting condition for variable refrigerant flow air conditioning system

Tu, Qiu; Xu, Jingqiang; Feng, Yuhai; Mao, Shoubo; Guo, Defang; He, Jianqi

doi:10.1016/j.enbuild.2012.01.012

Cited by 6 publications

(2 citation statements)

References 10 publications

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“…But these methods are only suitable for small air conditioners, and not for VRF AC system due to its characteristics. Qiu Tu 12 proposed the defrosting criterion model of time-coil temperature-condensation temperature, which was verified by experiments and a large number of engineering applications. In the model, a minimum defrosting cycle defined in the criterion model can avoid false defrosting and premature defrosting, and guarantee normal heating operation.…”

Section: Introductionmentioning

confidence: 85%

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Investigation of defrosting control function based on model and sequence diagram

Tu¹,

Feng²,

Liu³

et al. 2014

Building Services Engineering Research and Technology

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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.

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Section: Introductionmentioning

confidence: 85%

“…The model of defrosting arrival determination criterion is formulated as below 12 . and Here tr,AB, tr,BO, tr,OC and tr,CD are running time of the compressor between two defrosting events among four ambient temperature regions, respectively.…”

Section: Introductionmentioning

confidence: 99%