Research On Parameter Optimization Of Constant Temperature And Humidity AC System With Dual Loop Cooling Coil

In recent years,people’s life and social production put forward more and more requirements on the environment with rapid growth of economic.Air-conditioning systems(simplified as AC systems)are widely used for indoor air control to meet the requirements of temperature,humidity,cleanliness.Constant temperature and humidity AC systems are widely used in industry production and scientific research,which consume huge energy at the time of maintaining indoor environment.On the one hand,conventional constant temperature and humidity AC systems are all-air systems applying condensation dehumidification for humidity control and resulting re-heating and re-humidifying compensation power inevitably because this method cools air to temperature below the dew point.On the other hand,system needs higher frequency of ventilation than that in comfortable system to maintain the precise control of indoor temperature and humidity,which causes huge fan power consumption during all-year operation.Temperature and Humidity Independent control of Air-conditioning system(THIC),is very hot field in AC system research.THIC makes use of independent dehumidification technology to handle the indoor latent loads and high temperature cooling source to deal with the indoor sensible loads and so it avoids heating and humidifying compensation power at the root by decoupling the sensible loads and latent loads.But the structure of THIC system will be very complex,initial system investment will increase,system control will also be more complicated,and these problems prevent THIC system to be used widely.Our research team raised dual loop cooling coil to be used in constant temperature and humidity AC system.This system structure is very simple and system control is not difficult and it reduces large consumption power.Based on the system,this paper conducts the following work:(1)Coming up with the optimization method of constant temperature and humidity AC system in which dual loop cooling coil is used for dehumidifying;Setting up component models of AC system,getting object function of AC system energy,applying intelligent algorithm(PSO)for solving control parameters when system energy consumption is the least.(2)Designing and building the constant temperature and humidity AC system to launch experiment research with the purpose of verifying the AC system mathematical models.The comparison between simulation and experiment shows that maximum error of temperature is 0.37℃,relative error of absolute humidity is less than 5%,relative error of heat exchange of cooling coil is less than 10%.The error of AC system model satisfies the accuracy requirements of engineering and the system model can be used for optimization analysis.(3)Considering examples of four typical AHU conditions,this paper compares the operating performance of optimal control(optimize the cooling coil inlet parameters for system operation)with that of conventional control(constant cooling coil inlet temperature and mass flow),and researches on the energy saving of optimal control.Discussing the relation between energy saving ratio of optimal control and sensible loads,latent loads of AHU under two conditions:humidifying and dehumidifying.TRNSYS simulation software is used for dynamic simulation of optimal control.With the weather of typical meteorological year in Hangzhou as weather input in simulation,operating performance yearly of optimal control is researched and simulation results show that monthly average energy saving from Match to November is over 50%and that of other months is more than 45%as well.It shows well energy saving results under optimal control when AC system operating all year round.