Energy Simulation Analysis And Experimental Verification Of Air-cooled Variable-Refrigerant-Flow System Based On The Evaporation Temperature And Condensation Temperature Control Mode

In the conception and technological background of building energy saving, it is one of the most important concerns for the researchers in the building energy saving field in what manner of air conditioning to save energy. In the current researches on the air conditioning system simulation, simulation of the variable refrigerant flow system (VRF) is rare, and it is not found especially that VRF system simulation research combined with building energy simulation based on the variable evaporation temperature control and condensation temperature control mode is carried into the world.This dissertation introduces a newly developed energy simulation program which is further developed to achieve a variable evaporation temperature and condensation temperature control mode energy simulation for the VRF air conditioning system by a new generation of dynamic building energy simulation software EnergyPlus released by the U.S. Department of Energy based on the previous research work of Dr. Zhou Yanping on the original VRF system development in this software. Furthermore, it gives out the energy simulation results to do the comparative analysis of experimental results to study the impact of architectural input parameters, meteorological input parameters and performance curves of VRF system. This kind of work is aimed to effectively predict energy consumption of the VRF air conditioning system when selecting the VRF system type and capacity for an actual building. A series of theoretical and experimental research on this subject is included in this dissertation which can be described as follows:(1) Use the existing direct evaporative refrigeration cycle type heat exchanger coil model in EnergyPlus which is a building and system energy simulation tool to establish the VRF model through a dummy outdoor unit, and then find the energy consumption, COP, and PLR. It is convenient for getting accurate energy results based on simple inputs. To achieve energy simulation of variable evaporation temperature and condensation temperature control mode of VRF system, using the experimental data obtained based on the performance curves to simulate the VRF system when changing the evaporation temperature and the condensing temperature. This study has initially provide a possible method for the simulation program of variable evaporation and condensation temperature control mode of the VRF system model among the current international building energy simulation programs, making it possible to conduct annual energy consumption simulation of the VRF air-conditioning system.(2) Build the VRF system energy consumption test bench and establish local weather station, then finish two whole years including summer and winter seasons's measurement work to validate the accuracy of VRF system energy prediction model in a real building application. Compared with normal VRF system installations, the established test room and test VRF system have some notable features: simple and typical with one outdoor unit serving two indoor units configuration in a real building; internal heat gain is mimicked by the heaters and humidifiers in specific test spaces; weather data collection, indoor temperature setting, and system switching for all the systems with affiliated devices are controlled by PC; local weather station records meteorological data at an interval time of 10 minutes throughout the test period.(3) When VRF system is running in cooling mode, increasing refrigerant's evaporation temperature of indoor unit will save energy consumption and when VRF system is running in heating mode, decreasing refrigerant's condensation temperature of indoor unit will also save energy consumption. In this dissertation, the rationality and accuracy of the established VRF system simulation model under the above two running control modes is verified throughout the daily energy record comparison work between experimental data and simulation results and also what and where the major influence on the system power simulation results is found out. Furthermore, effective advice for model improvements is also put forward.