Abstract
The energy consumption of air-conditioning systems has gained increasing attention as it contributes significantly to the global building energy use. The variable refrigerant flow (VRF) system is a common air-conditioning system applied widely in residential and office buildings in China. Understanding the actual operation and performance of VRF systems is fundamental for the energy-efficient design and operation of VRF systems. Previous research on VRF system operation used either limited field data covering certain building types and climate zones or used a questionnaire to obtain a larger dataset. However, they did not capture the wide applications of VRF systems quantitatively across all building types, climate zones, and operating conditions.
Dataset introduction
The VRF dataset was established using the operation data of VRF systems monitored at the outdoor units. The VRF dataset includes two types of data: The installation information of the VRF systems, e.g., the building type, climate zone, and cooling and heating capacity, where users’ information has been anonymized, and the operational data, e.g., operation duration of outdoor units.
Use duration of VRF systems in different climate zones
The cumulative probability of use duration in different climate zones are calculated based on the dataset. Fig. 7 provides the cumulative probability curves of use duration in different climate zones for the same each time period in 2018. From December 2017 to February 2018, the use duration of 90% of the systems among all climate zones was less than 950 h (64% of the whole time, 1488 h). The use duration in the Hot Summer and Warm Winter zone was shorter than that of other climate zones, and
Potential applications of outcomes
Based on the data-mining results of the large VRF dataset, a few potential applications and recommendations can be drawn for VRF systems to improve their design and operation in China.
Policy implications
VRF systems are applied widely in China, mainly for residential and office buildings. VRF systems have high control flexibility and can meet the comfort needs of individual spaces, which is supported by data in this research. Data analysis in this research revealed the high diversity of occupant behavior and the part-time-part-space use mode is the main operation mode of VRF systems in China. In addition, data-mining results indicated that partial load issue is common. All the phenomenon found
Conclusion
This study performed statistical and clustering analysis of a large number of VRF systems for residential and commercial buildings in China across all five climate zones. Distributions of use duration and ideal performance of VRF systems across different climate zones and building types were derived from the actual VRF operation data. Represented load ratio patterns of VRF systems of residential and office buildings across all climate zones of China were developed, which can be used to inform
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