Research On Optimal Measuring Point Of Indoor Temperature And Humidity In VAV Air-conditioning System

In the actual air conditioning system,the temperature and humidity distribution in the room is not uniform,and the temperature and humidity values detected by the sensors at different positions may be different.The location of the sensor installation is not suitable so that the detection value does not reflect the true distribution of indoor temperature and humidity,and deviates from the real feeling of the indoor personnel;the indoor temperature and humidity control for the adjusted parameters usually causes the indoor environment to fail to meet the personnel demand.The actual temperature and humidity sensor in the air-conditioned room is integrated in the same device.Therefore,it is necessary to study the optimal measuring point of the indoor temperature and humidity sensor under the requirements of a certain index,to measure the temperature and humidity of the sensor at the optimal measuring point to the indoor temperature and humidity.Controlling,improving the indoor environmental control effect and improving the comfort of indoor personnel have very important theoretical significance and practical application value.In this paper,a university variable air volume experimental platform is taken as the research object,and the best temperature and humidity measurement points of air-conditioned rooms are studied.The specific research is as follows:(1)A room measuring point experimental platform was constructed based on the analysis of the variable air volume air conditioning system and the VAV BOX control principle.With reference to the ASHRAE Standard 55-2013 standard,six experimental planes in the room were selected to study the temperature and humidity measuring points.(2)A temperature-humidity recursive fusion algorithm based on optimal weighting is constructed.The algorithm improves the recursive fusion algorithm based on mean by introducing the weighting factor.The mean square error of the measured value and the weighted estimated value is constructed..The weight coefficient when minimized mean square error is multiplied by the measured value of each sensor,so that the sensor measurement data is fully utilized.The information loss caused by the randomness of the measurement data is reduced,and the influence of the extreme value on the fusion result is avoided.The study evaluated the temperature,humidity and wind speed with an effective temperature index ET(Effective Temperature),which unified multiple parameter points into one point to study the optimal installation position of the temperature and humidity sensor.(3)The air conditioning room simulation system was built by FLUENT software,and the temperature and humidity in the room were calculated.The temperature and humidity values of the experiment and FLUENT simulation were respectively used for data fusion based on the optimal weighted recursive fusion method.Finally,the human body temperature sensory index ET was used.With evaluation criteria,the optimal temperature and humidity measurement point is determined in the room.(4)The optimal temperature and humidity measurement point is usually in the midair of the room.It is not convenient to install the sensor.The orthogonal least squares method is used to study the mapping relationship between the optimal measurement point and the actual sensor installation point.The detected value of the measuring point sensor is corrected so that the corrected value is the same as the sensor value at the optimum measuring point.(5)The temperature and humidity values of the optimal and non-optimal measuring points are taken as controlled parameters respectively.The single-neuron PID is used to control the indoor temperature and humidity.The results show that when the optimal measuring point sensor value is taken as the controlled parameter,the thermal sensation of the indoor personnel is more consistent with the actual temperature and humidity value in the room.The temperature and humidity values detected by the optimal measuring point sensor can truly reflect the indoor temperature and humidity distribution,and the indoor environmental comfort level is improved to some extent.