Energy Consumption Simulation And Energy Saving Optimization Of Radiant Air-conditioning System In Office Buildings In Nanjing Area

With the improvement of living standards,people's requirements for various aspects of the indoor environment of buildings are constantly improving.As a new type of air conditioning,radiation air conditioning combined with displacement ventilation system has gradually developed,and its energy saving and comfort have attracted more and more attention of scholars.In this paper,a general office building in Nanjing is taken as the research object.The air conditioning system of this office building is roof radiation and displacement ventilation combined air conditioning system.EnergyPlus software is used to simulate the annual energy consumption distribution and typical daily energy consumption changes under different combination of cold and heat source equipment and different envelope structure conditions.Firstly,according to the different water supply temperatures of heat and cold sources,combined with the new energy-saving dual-source fresh air blower,the combined form of the system cold and heat source equipment is divided into three schemes:1)standard heat pump unit+high temperature water chiller+single-source fresh air blower;2)standard heat pump unit+plate heat exchanger+single-source fresh air blower;3)high temperature water chiller+dual-source fresh air blower.The specific operating conditions of the three schemes are compared and analyzed.The energy consumption of different schemes is simulated by EnergyPlus software.The simulation results show that the annual energy consumption of scheme 3 is 2.5%and 3.7%lower than that of scheme 1 and scheme 2 respectively,and the summer refrigeration energy consumption of scheme 3 is 17.0%and 23.1%lower than that of scheme 1 and scheme 2 respectively.This is because the third scheme maximizes the advantages of roof radiation and high water supply temperature for dual-cooling source fresh air fans.Moreover,the energy consumption of heating in winter is obviously higher than that of refrigeration in summer,which indicates that the thermal insulation performance of the envelope structure is poor,so the optimization and transformation of the envelope structure is a very important energy-saving measure.Then,based on the scheme of high temperature water chiller+dual cooling source fresh air fan,the energy-saving schemes of increasing the temperature of cold water on the roof in summer,reducing the temperature of hot water on the roof in winter,changing the air supply temperature and air supply volume are put forward respectively.The energy consumption of buildings under different working conditions is simulated.The simulation results show that the energy-saving effect is not obvious,but if the temperature of roof cold water is too high,the indoor temperature will be too high,the thermal comfort of human body will be poor,and the energy consumption will be increased.After increasing the temperature of roof hot water,the air supply temperature of the system and reducing the air supply volume,the overall energy consumption of the system will be reduced,and the energy-saving effect will be considerable.Finally,based on the scheme of high temperature water chiller+dual cooling source fresh air fan,the building envelope structure was modified by increasing wall insulation thickness and setting windows to shade the sun,and the energy consumption of the improved building was simulated.The simulation results show that the annual energy consumption of the office building decreases gradually with the increase of wall insulation thickness.Appropriate increase of wall insulation thickness can reduce heating energy consumption more than refrigeration energy consumption,and can effectively reduce the peak power of equipment,thereby reducing the design capacity of equipment;window shading has little effect on indoor temperature,and effectively reduces the refrigeration energy consumption of buildings,so optimizing window shading is one important measures of energy saving.According to the above energy consumption calculation results,it can be concluded that the roof radiation air conditioning system with dual-cooling source fresh air fans is more energy-saving than that with traditional single-cooling source fresh air fans,and that proper increase of wall insulation thickness and installation of window shading components can reduce the annual energy consumption of the office building.