Influence Of Permeable Spoiler Structure On Thermal Characteristics Of Heat Collector And Simulation Optimization

The solar air collector is the main component of the solar drying device,and is also one of the commonly used solar heat utilization devices.Its heat collection efficiency is an important index to evaluate its performance.In view of the turbulence phenomenon in the inner part of the air collector,this thesis proposes to adopt the permeation structure in the area where the turbulence exists to diffuse the turbulence in the inner part of the collector,so as to reduce the resistance of the air in the collector cavity and make the air contact with the heat absorbing plate further fully,so as to improve the heat collection efficiency.In this thesis,with the same heat collecting area,spoiler length and number of spoilers of the collector is taken as the research object to study the influence of pore position,size and porosity of permeable structure on its heat collecting efficiency.The research contents include experimental research,simulation modeling analysis and structural optimization simulation research and verification.The conclusions are as follows.(1)Under real-time weather conditions,thermal characteristics tests were carried out on collectors with permeable spoiler structure(test group)and ordinary spoiler structure(matched group),and the temperature rise rate at the collector outlet and air flow loss were taken as indexes to obtain the following conclusions:The permeable structure of the spoiler can reduce the turbulence at the junction between the collector side wall and the spoiler,that is,the gas flow velocity at the corner is accelerated,and the gas flow velocity in the collector cavity is increased obviously.With the increase of the number of holes,the temperature rise of the air flow at the outlet of the collector increases and the loss rate of the air flow decreases accordingly.However,in the case of the same permeable area of the spoiler,the collector efficiency is not proportional to increasing.When the porosity reaches a certain degree(large aperture),the temperature rise of the collector decreases and the airflow loss rate also shows a decreasing trend.The starting and ending positions of the spoiler penetration holes have a significant effect on the thermal characteristics and efficiency of the collector.There are interaction between spoiler penetration area,aperture size and permeability.(2)Based on ANSYS Fluent fluid simulation software,the simulation model of the solar air collector for the experiment device was established,and the air flow field and temperature field inside the solar air collector were numerically simulated and verified.The results show that the simulation results of temperature field and flow field are consistent with the experimental results of temperature rise and flow loss.(3)A numerical model is used to conduct the best matching study on the permeability area and permeability.The results show that: on the existing 700 mm long spoiler,the permeability area is 1/2 of the plate length,and the collector efficiency is 17.67% Is the best.t.