Simulation And Optimization Of Temperature And Humidity Field In Curing Rooms For Prefabricated Concrete

At present,the three-dimensional curing rooms with the steam curing system have been widely used;however,in the actual operation,such curing rooms often have a phenomenon that the temperature and humidity fields are unevenly distributed,resulting in that some of the prefabricated components that have been cured don’t reach the required late strength;therefore,this article models and simulates the temperature and humidity field of a curing room,and optimizes the steam curing system according to the existing uneven temperature and humidity distribution problems and high energy consumption of the existing system.The main work is as follows:（1）Firstly according to the condensation phenomenon inside the curing room,two condensation models are established:the wall condensation model and the mist condensation model;The simulation results of the reference case by using the two condensation models are within 10%of the experimental values,the.So the accuracy of the condensing model in the temperature and humidity simulation of the curing room is verified.（2）Obtained by simulation results,the curing room temperature gradually increases with time,the heating rate gradually decreases,and the maximum heating rate is 15°C/h.At 120 minutes,the average temperature at the top reaches 50°C.The average temperature difference in the height direction does not exceed 1.5°C;The homogeneity of the temperature at the upper part is better than the lower part of the room,and the overall temperature distribution is high in the periphery and low in the middle;the area with the highest temperature is at the bottom of the lowest prefabricated concrete layer.The gap between the prefabricated parts achieves the lowest temperature in the chamber,and the lowest temperature is only about 43°C.（3）After steaming for 20 minutes,the humidity in most areas of the curing room reaches saturation,except the high temperature area near the heating plate at the bottom of the chamber.As the humidity gradually becomes saturated,the condensation rate in the chamber gradually becomes larger and tends to be stable;the wall surface condensation rate of the prefabricated component is on the order of 10^-4 kg/（m²·s）;the mist condensation rate in the chamber is on the order of 10^-5 kg/（m³·s）.（4）The reduction of the temperature of the heating plate has few influence on the overall temperature distribution,but it can reduce the thermal damage to the bottom prefabricated component and make the hot air between the prefabricated components more and more uniform.An upward movement of the position of the heating plate can cause an upward movement of the area disturbed by the hot air between the prefabricated components.The downward movement of the heating plate reduces the temperature difference in the height direction,and the temperature difference can be reduced by up to 2°C.（5）The chamber temperature is more uniform when steam is injected downwards.The temperature distribution is most even when the nozzle is located at 46%to 65%of the total height;the increase in the number of nozzles can effectively reduce the temperature in the lower region between them.（6）A trough solar steam generation system is established in the prefabricated plant to produce 691.3 tons of steam throughout the year.Calculated according to the maximum load of the maintenance system,the annual solar energy guarantee rate is 15.8%.（7）Calculated on the basis of 10 years of use,the average energy cost of the trough solar steam generation system is 0.02 yuan/MJ,which is only7.1%of the energy cost of electricity and 18.2%of the energy cost of natural gas;the cost recovery period of this system is 4.8 years.At the same time,208.29 tons of carbon dioxide,0.68 tons of sulfur dioxide,0.59tons of nitrogen oxides,and 1.99 tons of dust emissions can be reduced annually.