Research On Simulation And Control Strategy Development Of Direct Expansion Air-conditioning Systems Aiming For Simultaneously Improving Thermal Comfort And Energy Efficiency

Compared with central air conditioning system,direct expansion air conditioner is widely used in small-to-medium-sized buildings for it's simple in structure and easy to maintain.And it's also known as room air conditioner.In 2018,the amount of domestic air conditioner in China has researched 109.3 per hundred families.Considering the large amount,it's meaningful to focus on how to reduce the energy consumption of room air conditioner.The related research mainly focused on improving equipment performance such as improving the efficiency of compressor and heat exchanger.At the same time,the control method and target are still simple.Most air conditioners on the market are only able to control indoor temperature.Few of them have the ability to control both indoor humidity and temperature,needless to say optimizing the humidity and temperature set point.However,it's critical to control both temperature and humidity for indoor thermal comfort and air quality since people feel uncomfortable when the indoor humidity is either too high or too low.On the other hand,the indoor temperature and humidity affect the air conditioner energy consumption by affecting cooling load and air conditioner efficiency.There exists a humidity and temperature set point which can satisfy both thermal comfort and energy consumption.In this thesis,research on energy-saving control method of variable frequency air conditioners was first introduced.Then the temperature and humidity simultaneous control method used in this research was presented.The structure of the direct expansion air conditioner experiment rig was described.After comparing different kinds of modeling method,ANN(artificial neutral network model)was chosen to simulate air conditioner using the data from the experiment rig.The influence of indoor temperature and humidity on cooling load and air conditioner energy efficiency was discussed by air conditioner model and literature research.A control strategy of direct expansion air conditioner was developed which could optimize and control the indoor temperature and humidity based on thermal comfort and energy consumption.The detail of the control strategy was introduced.The control strategy was tested on the experiment rig.The experiment result showed that the control strategy could save more than 20% energy and satisfy thermal comfort at the same time.To some extent,it could avoid the problem that the temperature and humidity set point was uncontrollable even when the load was beyond the range of cooling and dehumidification capacity.The control strategy also had self-learning ability which could adjust PMV set point based on user's feedback.