Optimization Simulation Of Temperature Field And Temperature Enhancement Mode In Cold Area Biogas Tank

With the depletion of mineral resources and the increasing serious environmental problems,the development and utilization of new clean energy has become an important issue in China's economic development.As a kind of clean energy,biogas has high calorific value and it can product conveniently.The most important aspect is to deal with pollution waste and produce economic benefits at the same time,biogas fermentation technology and biogas engineering technology in recent years developed very rapidly.In the process of biogas fermentation,there are many factors affecting the output of biogas fermentation:such as the selection of raw materials,fermentation temperature,design of mixing fermentation control device etc..The greatest impact is the fermentation temperature control,it directly restricts the anaerobic fermentation of bacteria.In the northeast cold area,because of the long winter time and low external temperature,only the proper fermentation temperature can be guaranteed to increase the biogas production.The previous increase temperature design in biogas digesters reference other fermentation process device design,and it has no rigid standards.This study based on a long-term and sustainable operation of the biogas engineering,biogas heating coil and stirring device were doing comparative research and select the most appropriate increase temperature scheme to improve the engineering integrity.As a flow field and temperature field numerical simulation software technology,with the engineering industry experts and scholars likely,the fluent is widely used in practical engineering analysis,in this study the software FLUENT was used to simulate the working conditions of engineering test.Taking account that the biogas fermentation raw material composition is complex,but throughthe past research showed that biogas slurry belong to the false plastic fluid in the rheological properties and density of the slurry section,the concentration can be approximately regarded as a Newtonian fluid.So as to simplify the calculation in this study,the biogas slurry is designed for the single phase flow system,the solid concentration is 12%,viscosity is 179.54 m Pa · s,density ? = 1.23/ cm~3.In this study,the experimental study and numerical simulation are combined in biogas fermentation device temperature field to make a contrast study of the test,through the mixing of each heating measured different layer height of temperature data we can analysis the running situation of the current conditions about the methane fermentation device;By using fluent numerical simulation software to simulate the mixing process in flow field and temperature field distribution,using second order upwind turbulence model of liquid turbulence characteristics to expound,the use of multiple reference frame method about fermentation tank computational domain is divided into dynamic and static two regions,the fluid flow and heat transfer characteristics of three-dimensional temperature field in numerical simulation of the flow field.Then the simulation results are compared with the experimental data to ensure the feasibility of Fluent software simulation technology in the research of temperature field of biogas fermentation equipment;Followed by stirring device of eccentric type optimization and transformation,from different stirring device from the bottom of the height and the heating coil and the location of laying down of simulation analysis and research,at the same time,using the TRNSYS software and numerical analysis theory discussed to simulated the economic energy-saving warming.The main results of this study are as follows:(1)In this study,a pig farm biogas project in Changchun city as the test object,the results of the test temperature monitoring and numerical simulation oftemperature field,flow field distribution effect is consistent.The results show that the temperature field and the flow field are feasible in the simulation of biogas fermentation process by using Fluent software,which is a guiding role for the numerical simulation of the next step.(2)This study based on the test data and the simulation analysis based on the fermentation stirring device was used to optimize the eccentric,also makes eccentric installation plan B deep numerical optimization,changing the stirring device height and the heating coil pipe laying position,combine e three new kinds of marsh gas stirring device and coil arrangement scheme by using CFD software,analysis of three tank material liquid temperature field distribution.The results showed that three cases had impact on the liquid at the top 4.5m of heat transfer,the scheme of E for liquid heat transfer and uniform temperature distribution in the best effect.(3)Using the systematic TRNSYS software to simulate the operation of biogas project under different heat source,compared with the economic and energy consumption of heat recovery and the way of solar energy heating,ground source heat pump heating.The results show that the waste heat recovery heating method is more suitable for the biogas project in cold area.