Optimal Design And Performance Simulation Of Constant Temperature And Humidity Air-Conditioning System

The energy saving strategy researches for the HVAC system play an important role in decreasing the energy cost of the building and realizing sustainable development. The constant temperature and humidity air-conditioning system belongs to the process air conditioning, which is mainly used to control the indoor parameters, such as the air temperature, relative humidity, cleanliness and so on, in some specific ranges. For the conventional constant temperature and humidity air-conditioning system, a large energy compensation is caused by the fixed chilled water flow rate and fixed dew point on the cooling coil. As a result, an optimal design, using a temperature and humidity independent control (THIC) device in the CC and a method of PID split-range control, is presented in this paper. And the following researches have been done.1. First, the optimal design is explained in detail; and then an actual system is built according to this method to prove this design is practical;2. Based on the TRNSYS16software, the model of the actual system is developed; and the operation states of the system under different heat and moisture loads are analyzed detailed. When the air should be cooled or dehumidified, the cooling coil can guarantee one parameter of the air temperature or the relative humidity, while the other is controlled by the heater or the humidifier. Compared to the conventional system, just two components of the cooling coil, the heater and the humidifier could realize the precise control; so the energy compensation is decreased largely; 3. The annual performance of the optimal system is simulated by employing the Typical Meteorological Year of Hangzhou. The results show that the optimal system could ensure a good temperature and humidity level for the whole year, and the system could get an energy saving rate of42.5%under the simulation condition, compared to the conventional system. In the end, an analysis on the energy saving by decreasing the set point of the space temperature is presented, and show that3.6%of the energy cost is saved if changing the set point of22.0℃to21.0℃.