Research On Energy Consumptions Of Radiation Air Conditioning On The Basis Of Evaporative Cooling And Mechanical Refrigeration

Adopting the EnergyPlus, as dynamic energy simulation software, a simulation was made on energy consumptions of an office building in Xi’an, taking the radiation air conditioning system on the basis of evaporative cooling and mechanical refrigeration as research objects. The development background and the working principle of EnergyPlus were briefly introduced. The mathematical model of air conditioning system components was also analyzed.A model for radiation air conditioning system which was operated jointly by evaporative and mechanical refrigeration was built; a comprehensive introduction to methods that the energy simulation software uses to build air conditioning system was made; comparisons of the comfort degrees and energy consumptions between two different kinds of air-conditioning systems in the same office building were also made. In addition, a comprehensive analysis of energy saving potentials for radiation air conditioning system which is based on evaporative cooling and mechanical refrigeration was also made. Main conclusions are as follows:(1) The cooling time in summer is from June1to September30(a total of four moths,122days). Without regard to36-day weekends, the actual cooling running time in summer is86days. The daily running time is from8:00to18:00. The total running time of cooling system is up to860hours. The simulation results show that from June to September, the time when radiation air conditioning system only use evaporative cooling is up to378hours, while the time when radiation air conditioning system jointly use evaporative cooling and mechanical refrigeration is up to482hours. The former accounts for44%of the overall running time, while the latter56%.(2) In July21, as the design day of summer, the average temperature of the working region for the composite air-conditioning system reaches27.45℃, which can well satisfy the requirements to indoor comforts. In the meanwhile, the cooling load reaches its peak at15:30in the design day of summer. The peak loading value is52.3kW.(3) In the design day of summer, average temperatures for the radiation air-conditioning system based on the evaporative cooling and mechanical refrigeration (Systeml) and primary air fan-coil system (system2) respectively are27.3℃and25.7℃. Their averages PMV respectively are-0.42and0.33.(4) Energy consumptions of the radiation air-conditioning system on the basis of evaporative cooling and mechanical refrigeration in summer are evaporative chillers and supply fan, which respectively account for43%of the total energy consumption of the system and25%. However energy consumptions of the primary air fan-coil system are mainly mechanical refrigeration whose energy consumption accounts for more than70%of the entire summer energy consumption of the system.(5) The average hourly energy consumption of air-conditioning systems based on evaporative cooling and mechanical refrigeration is7.54kW less than that of the primary air fan-coil system. In addition, the energy consumption of air-conditioning systems based on evaporative cooling and mechanical refrigeration is only40.8%of that of the primary air fan-coil system. Regarding the electricity price in Xi’an as0.7Yuan/kWh in the estimate, compared with system2, the running cost of system1in summer is4538.9Yuan (8.65Yuan/square) less.