• Title/Summary/Keyword: Variable refrigerant flow system

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Case Study of Hybrid HVAC system Applied VRF (VRF 응용 Hybrid 공조시스템 Case Study)

  • Kim, Seong-Sil;Park, Wan-Kyu;Hur, Inn-Ju
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.357-362
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    • 2008
  • The present study has been conducted variable refrigerant flow system applied building. Multi air-conditioning system has some benefits : easier building management and maintenance and energy saving. Recently, the system heat pump has been employed in medium-sized and tall buildings. However, the performance data and design method for system heat pump are limited in literature due to complicated system parameters and operating conditions. In the present study, case study of a system heat pump applied various building. The aim of this paper is to application multi air-conditioners and to inform the benefits of multi air-conditioners.

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Development of Comfort Control Logic for VRF System in Summer Season by using 3 Environment Factors(Temperature, Humidity and Air flow) (온도, 습도, 기류를 이용한 하절기 VRF 시스템의 쾌적 제어 알고리즘 개발)

  • Kim, Jong-Min;Choi, Jae-Boong;Lee, Sang-Won;Cho, Doo-Ho;Lee, Pil-Ho;Kim, Young-Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.9
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    • pp.610-619
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    • 2011
  • This paper investigates the simplified comfort index and control logic for VRF (Variable Refrigerant Flow) system by using 3 environmental factors such as temperature, humidity and air flow. Indoor test under thermal load was conducted to explore relationship of each environment factors that is related to simplified comfort index. Simplified comfort function that has 3 environmental variables was proposed based on survey results. Each factor is measured and comfort preference was surveyed by more than 30 subjects in the indoor comfort test. Moreover, control logic for VRF system was developed and then simulated by using thermal load calculation method and verified with test. The proposed comfort function was in good agreement with survey results, and also verification test trend of comfort change and maintenance are quite similar with survey. Furthermore, through the additional test data analysis some differences of comfort according to position of people staying in the test room were additionally investigated by air flow. People being under an exit of air in the indoor air-conditioner feel more comfortable condition and speed of response to comfort change is relatively fast.

ANN-Based VRF (variable refrigerant flow) system control (인공신경망 기반 VRF 시스템 제어)

  • Moon, Jin Woo
    • LHI Journal of Land, Housing, and Urban Affairs
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    • v.10 no.3
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    • pp.9-16
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    • 2019
  • This study aimed at developing control algorithms for operating a variable refrigerant flow (VRF) heating and cooling system with optimal system parameter set-points. Two artificial neural network (ANN) models, which were respectively designed to predict the heating energy cost and cooling energy amount for upcoming next control cycle, was developed and embedded into the control algorithms. Performance of the algorithms were tested using the computer simulation programs - EnergyPlus, BCVTB, MATLAB in an incorporative manner. The results revealed that the proposed control algorithms remarkably saved the heating energy cost by as much as 7.93% and cooling energy consumption by as much as 28.44%, compared to a conventional control strategy. These findings support that the ANN-based predictive control algorithms showed potential for cost- and energy-effectiveness of VRF heating and cooling systems.

Operation Results and Utility of Dynamic Pricing Response Control-Applied VRF System in Summer Season

  • Kim, Min-seok;Lee, Je-hyeon;Song, Young-hak
    • Architectural research
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    • v.19 no.3
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    • pp.71-77
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    • 2017
  • Dynamic pricing refers to a system in which a tariff varies, according to a level of charging and applied time depending on time change. The power billing system used in the Korean Electric Power Corporation (KEPCO) is based on time of use (TOU) pricing, which is one of the dynamic pricing systems. This paper aimed to determine the operational results of a variable refrigerant flow system, to which a new control algorithm was applied, in order to respond to dynamic pricing, in summer and the utility of the new control. To do this, real measured data was acquired from a VRF system installed in a building for educational purposes, where dynamic pricing was applied for about 100 days during summer time. At the maximum load operation time period in TOU, the new control minimized operation within the indoor comfort range, an increase in refrigerant evaporation temperature in the indoor unit and the number of revolutions in a compressor in the outdoor unit was limited. As a result, power usage was decreased by 11%, and the operational cost by 14.6%. Furthermore, measurement results using the Predicted Mean Vote (PMV) model, that represented satisfaction of thermal environment, showed that 82.8% to 90.4% of the occupants of the building were satisfied during operation when the new control was applied.

A Study on Winter Season Measurement Results to cope with Dynamic Pricing for the VRF System

  • Kim, Hwan-yong;Kim, Min-seok;Lee, Je-hyeon;Song, Young-hak
    • Architectural research
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    • v.17 no.3
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    • pp.109-115
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    • 2015
  • The dynamic pricing of electricity, where the electricity rate increases in a time zone with a high demand for electricity is typically applied to a building whose power reception capacity is greater than a certain size. This includes the time of use(TOU) electricity pricing in Korea which can induce the effect of reducing the power demand of a building. Meanwhile, a VRF (Variable Refrigerant Flow) system that uses electricity is regarded as one of the typical heating and cooling systems along with central air conditioning (central HVAC) for its easy operation and application to the building. Thus, to reduce power energy and operating costs of a building in which the TOU and VRF systems are applied simultaneously, we suggested a control for changing the indoor temperature setting within the thermal comfort range or limiting the rotational speed of an inverter compressor. In this study, to describe the features of the above-mentioned control and verify its effects, we evaluated the results obtained from the analysis of its operation data. Through the actual measurements in winter operations for 73 days since mid- December 2014, we confirmed a reduction of 10.9% in power energy consumption and 12.2% in operating costs by the new control. Also, a reduction of 13.3% in power energy consumption was identified through a regression analysis.