Shin, Younggy Karng, Sarng Woo Kim, Seo Young 2024-01-20T10:02:37Z 2024-01-20T10:02:37Z 2021-09-05 2014-04 0140-7007 https://pubs.kist.re.kr/handle/201004/126921 A multi-split VRF system operates unsteadily most of time due to the constantly varying refrigerant flow rates of associated indoor units. VRF systems require a different approach from conventional techniques to detect faults, which have developed based on steady-state operations. In this paper, two fault detection techniques are proposed. Their advantage is that they do not require the test data to be preprocessed to obtain steady-state data. The first technique is applied to detect heat exchanger fouling by a state observer, and the other technique is used to detect valve sticking by temperature variance. These techniques were not chosen haphazardly but were derived from physical reasoning. Their validity was confirmed by test data. The methodology developed in this study can be applied similarly to other HVAC equipment that operates mostly in transient states. (C) 2013 Elsevier Ltd and IIR. All rights reserved. English ELSEVIER SCI LTD DIAGNOSIS SENSOR STRATEGY Indoor unit fault detector for a multi-split VRF system in heating mode Article 10.1016/j.ijrefrig.2013.11.009 1 INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID, v.40, pp.152 - 160 INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID 40 152 160 scie scopus 000337016200015 2-s2.0-84893203826 Thermodynamics Engineering, Mechanical Thermodynamics Engineering Article DIAGNOSIS SENSOR STRATEGY FDD (fault detection and diagnosis) Heat exchanger fouling State observer Multi-split VRF (variable refrigerant flow) Heat pump