TY - JOUR T1 - Development and validation of a new variable refrigerant flow systemmodel in EnergyPlus JF - Energy and Buildings Y1 - 2015 A1 - Tianzhen Hong A1 - Kaiyu Sun A1 - Rongpeng Zhang A1 - Ryohei Hinokuma A1 - Shinichi Kasahara A1 - Yoshinori Yura KW - building simulation KW - energy modeling KW - energyplus KW - Heat pump KW - model validation KW - Variable refrigerant flow AB -

Variable refrigerant flow (VRF) systems vary the refrigerant flow to meet the dynamic zone thermalloads, leading to more efficient operations than other system types. This paper introduces a new modelthat simulates the energy performance of VRF systems in the heat pump (HP) operation mode. Com-pared with the current VRF-HP models implemented in EnergyPlus, the new VRF system model has morecomponent models based on physics and thus has significant innovations in: (1) enabling advanced con-trols, including variable evaporating and condensing temperatures in the indoor and outdoor units, andvariable fan speeds based on the temperature and zone load in the indoor units, (2) adding a detailedrefrigerant pipe heat loss calculation using refrigerant flow rate, operational conditions, pipe length, andpipe insulation materials, (3) improving accuracy of simulation especially in partial load conditions, and(4) improving the usability of the model by significantly reducing the number of user input performancecurves. The VRF-HP model is implemented in EnergyPlus and validated with measured data from fieldtests. Results show that the new VRF-HP model provides more accurate estimate of the VRF-HP systemperformance, which is key to determining code compliance credits as well as utilities incentive for VRFtechnologies.

VL - 117 U2 - LBNL-1004499 ER -