Energy Consumption Analysis Of Hybrid Radiant Cooling Air-conditioning System Based On Evaporative Cooling

Energy consumption of hybrid radiant cooling air-conditioning system based on evaporative cooling was analyzed by whole building energy analysis tool EnergyPlus. The main research contents and conclusions are as follows.(1) Operating principle and mathematical model of air-conditioning component in EnergyPlus was studied. In order to ensure accuracy, the weather data of two cities (Kashi and Lanzhou) in EnergyPlus were compared with the data of weather stations. The biggest temperature error is7.4℃in February in Kasha of Xinjiang, the absolute error of temperatures in the rest months are less than3℃. The relative humidity is around the data of weather stations, the biggest error is10%. The weather data of EnergyPlus is comparatively accurate. The related equipment in the hybrid system was simulated. The outlet water temperature of cooling tower is1.9℃higher than the wet bulb temperature of the inlet air, indicating that the simulation of outlet water temperature in the cooling tower is accurate. A two-stage evaporative cooling air conditioning unit with tubular indirect evaporative cooling as first stage, and direct evaporative cooling as second stage were chose as simulation object. The outlet temperatures and efficiency of each stage were simulated by EnergyPlus. By comparison of simulation results and measured data, the simulation error of efficiency is within3%, indicating that the simulation of two-stage evaporative cooling air conditioning unit is relatively accurate. The energy consumption analysis of this two-stage evaporative air cooling conditioning unit demonstrated that its COP is11.9, much lower than that of traditional air conditioning equipment.(2) The building model and hybrid radiant cooling and displacement ventilation air-conditioning system model were established. Compared with experimental data, the error of indoor air temperature and cooling capacity supplied by radiant floor is within7%under similar outdoor temperature, indicating that the simulation of the building model and hybrid radiant cooling and displacement ventilation air-conditioning system model is relatively accurate. Based on the building model and hybrid radiant cooling and displacement ventilation air-conditioning system model, the cooling capacity supplied by hybrid radiant cooling and displacement ventilation, floor surface temperature, mean indoor temperature, AUST temperature with the change of supply air parameters or supply water parameters were obtained. Combined with the indoor thermal comfort model, when indoor thermal comfort PMV is between-0.5and0.5, the recommended supply air parameters and supply water was obtain.(3) In order to study the energy saving performance of hybrid radiant cooling air-conditioning system based on evaporative cooling, three different air-conditioning systems were designed for an office room located in Urumqi. These three systems are hybrid radiant cooling air-conditioning system based on evaporative cooling, two-stage all-air evaporative cooling system and primary air fan-coil system based on mechanical refrigeration. The energy consumptions of these three systems from May1st to September30th were simulated by EnergyPlus. Compared with mechanical refrigeration based air conditioning system, hybrid radiant cooling air-conditioning system based on evaporative cooling and two-stage evaporative cooling system is more energy efficient. Due to the increase of designed indoor air temperature and water adopted as the coolant, hybrid radiant cooling air-conditioning system based on evaporative cooling is45.2%efficient than two-stage evaporative cooling system. Moreover, hybrid radiant cooling air-conditioning system based on evaporative cooling is more energy efficient than primary air dry fan-coil air-conditioning system based on evaporative cooling.