Methods for performance metering of indoor units in variable refrigerant flow systems based on built-in sensors

Xiao, Hansong; Yang, Zixu; Shi, Jingfeng; Wang, Baolong; Shi, Wenxing

doi:10.1016/j.applthermaleng.2021.117268

Cited by 8 publications

(2 citation statements)

References 27 publications

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“…The available papers address the problem for a specific CCS (e.g., variant refrigerant flow (VRF) systems). As for example, in [9], authors reviewed the methods of individual energy metering for VRF systems. Three new methods were proposed, based on the electronic expansion valve, machine learning and throttling model.…”

Section: Introductionmentioning

confidence: 99%

Individual metering and submetering for cooling application

Aprea¹,

Canale²,

Dell’Isola³

et al. 2023

Proceedings of the 19th International Flow Measurement Conference 2022 on Flow Measurement - FLOMEKO 2022

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In 2012 the Energy Efficiency Directive (EED) has set mandatory installation of individual metering and submetering systems for accounting thermal energy consumption in buildings where centralized heating/cooling sources are present, when technically feasible and cost efficient. As a consequence, direct thermal energy meters or indirect heat accounting systems have spread widely in residential buildings, for metering and submetering in space heating applications. On the other hand, individual metering of thermal energy in space cooling is a difficult task, due to the very different types of cooling systems and to the lack of technical and legal metrology regulation. In this paper possible solutions available for direct metering and submetering of different types of centralized cooling systems are discussed. Indeed, for direct metering application, the cooling fluid flow metering is a particularly crucial issue due to small pipe diameters and different fluid properties. Thus, the authors carried out an experimental comparison between a Coriolis flow-meter and an ultrasonic clamp-on flowmeter in the cooling fluid circuit of a direct expansion system. Tests have been performed at different operative temperature differences between flow and return, showing relative errors within ± 10%.

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Section: Introductionmentioning

confidence: 99%

Individual metering and submetering for cooling application

Aprea¹,

Canale²,

Dell’Isola³

et al. 2023

Proceedings of the 19th International Flow Measurement Conference 2022 on Flow Measurement - FLOMEKO 2022

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“…Different non-intrusive methods have been proposed in the scientific literature, based on the throttling characteristics of electronic expansion valves, pressure drop, and refrigerant density [36,37] or considering the volumetric efficiency of the compressor [38]. In 2021, Xiao et al [39] proposed three new metering methods for VRF systems, based respectively on machine learning, a throttling model, and an electronic expansion valve. The three methods respectively showed accuracies of 6.9%, 6.0%, and 7.8%.…”

Section: Introductionmentioning

confidence: 99%

On the Use of Ultrasonic Flowmeters for Cooling Energy Metering and Sub-Metering in Direct Expansion Systems

et al. 2023

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The Energy Efficiency Directive (EED, Directive 2012/27/EU) has made mandatory the installation of individual metering systems in the case of buildings with centralized heating/cooling and hot water sources (multi-apartment and multi-purpose buildings), provided it is economically and technically feasible. Individual metering of heating/cooling systems is mainly based on thermal energy meters (TEM), which are widely used for direct metering in heating applications. On the other hand, direct metering of energy consumption in cooling systems still represents a challenge, given the different types of cooling units and the lack of regulations from the technical and legal points of view. In this context, this paper briefly overviews the available centralized cooling systems and the possible solutions for metering and sub-metering, which depend on the specific application. Vapour Compression Refrigeration (VCR) systems are spreading worldwide for air conditioning applications. Particular attention has been paid to the direct metering of cooling energy and specifically to refrigerant flow rate measurement, which represents a critical issue because of the small-diameter pipes and the different thermodynamic properties of the fluid used. Thus, an experimental campaign has been developed and carried out in order to compare a clamp-on ultrasonic flowmeter with a more accurate Coriolis one in a direct expansion (DE) system. The experimental tests have been performed at two different temperature conditions, showing a relative error in the mass flow rate measurements within ±10%.

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