Control System Design For Smart Cooling Garments

With the rapid technological advancement of the cooling system,indoor temperature and humidity are both under precise control even in torrid summer.While for people working outside like traffic police officers and firefighters,indoor air conditioners may not be an option.With heavy heat load,they are prone to heat-related injuries which may put their lives in danger.Even though some personal cooling garments such as air-cooled garments(ACG),liquid cooling garments(LCG),phase change garments(PCG),and evaporative cooling garments(ECG)may offer some help,the process of heat dissipation is not as precisely controlled as air conditioners do.Temperature fluctuation and regional overcooling can still cause thermal discomfort.In order to improve thermal comfort,a portable liquid cooling garment with temperature control system has been developed.According to a simplified Human-LCG-Environment heat transfer model,flow rate and inlet water temperature are two factors that can be utilized in the design of a temperature control system.From further experimental results,the flow rate proves to be effective in temperature control only at a lower range while has little impact on the effective cooling time at a higher range;and the inlet water temperature is capable of improving thermal comfort as well as elongating total cooling time.To implement such a temperature control system,we designed circuits and firmware for it which gave us access to real-time sensor data such as environmental temperature and humidity,ice temperature,inlet water temperature,workload and battery usage from a smartphone through Bluetooth connection,as well as the ability of remote control.Finally,the system yields three different control modes: manual mode,thermostatic mode,and automatic mode.Under manual mode,the pump speed and valve opening have to be adjusted manually.Under thermostatic mode,the inlet water temperature is stabilized around setpoint by a PID controller with an accuracy of ±0.5?.And under automatic mode,the pump speed and inlet water temperature are set automatically according to the predicted remaining time for the battery and icepack.The remaining time for the battery is predicted using ANN with an average accuracy of 150 seconds,and the remaining time for icepack is predicted using RNN with an average accuracy of 60 seconds.