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Title: Field test and simulation evaluation of variable refrigerant flow systems performance

Our study aims to compare the performance of a Variable Refrigerant Flow (VRF) system with a Roof Top Unit, (RTU) and a variable-air-volume (VAV) system through field tests and energy simulations. The field test was conducted in as similar conditions as possible between the two systems, such as the installation and operating environments of heating, the ventilation and air conditioning (HVAC) system, including internal heat gain and outdoor conditions, including buildings to compare the performance of the two systems accurately. A VRF system and RTU were installed at the test building located in Oak Ridge, Tennessee, in the USA. The same internal heat gain was generated at the same operating time of the two systems using lighting, electric heaters, and humidifiers inside the building. The HVAC system was alternately operated between cooling and heating operations to acquire energy performance data and to compare energy usage. Furthermore, an hourly building energy simulation model was developed with regard to the VRF system and RTU, and then the model was calibrated using actual measured data. Then, annual energy consumption of the two systems were compared and analyzed using the calibrated model. Moreover, additional analysis was conducted when the controlled discharge air temperature inmore » the RTU was changed. The field test result showed that when energy consumptions of two systems were compared at the same outdoor conditions, using the weather-normalized model, the VRF system exhibited an energy reduction of approximately 17% during cooling operation and of approximately 74% during heating operations. A comparison on the annual energy consumption using simulations showed that the VRF system reduced energy consumption more than that of the RTU by 60%. Furthermore, when the discharge air temperature in the RTU was controlled according to the outdoor air temperature, energy consumption of the RTU was reduced by 6% in cooling operations and by 18% in heating operation. As a result, energy consumption of the VRF system was reduced by more than that of the RTU by 55% approximately.« less
 [1] ;  [2] ;  [3]
  1. Samsung Electronics, Gyeonggi-do (South Korea). Dept. of Digital Appliances R&D Team, Samsung Electronics
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Building Technologies Research Integration Center (BTRIC)
  3. Gyeongsang National Univ., Jinju City (South Korea). Dept. of Architectural Engineering
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Energy and Buildings
Additional Journal Information:
Journal Volume: 158; Journal Issue: C; Journal ID: ISSN 0378-7788
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
Country of Publication:
United States
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; variable refrigerant flow system; roof top unit; field test; simulation; annual energy performance
OSTI Identifier: