Energy Conservation Optimization On Displacement Ventilation Of Large Space Welding Factory

Energy consumption has become a global problem nowadays,especially the energy consumption on buildings. It has been reported that the energy consumption on buildings in China has been on the top of all industrial fields, which is approximately 33% of the total energy consumption. As a result of the prompt development of the construction industry and the significant growth of the living standard of people, more energy is required in the buildings, especially the energy on heating and cooling of the buildings. The realization of the energy conservation in high welding plant with heat source and pollutant source is a common challenge at present, which is resulted from the requirements of ideal thermal comfort and good indoor air quality. Displacement ventilation,characteristic of an airflow organization of down-supply & up-return and an air-supply of low velocity and low temperature differences, has been a potential choice for the high welding plant. Therefore, displacement ventilation is chosen as the method for the energy conservation of high welding plant in this research.To study the energy saving effect of the displacement ventilation in high welding plant, CFD and Design Builder were adopted during the research. Firstly, the temperature distribution and Ozone concentration under two different air-supply temperatures and five different airflow rates in the plant were analyzed by the CFD numerical simulation; then,the energy consumption of the conditions above during cooling seasons was analyzed by Design Builder. Considering the results by CFD simulation and Design Builder, the lowest energy consumption pointed to the condition with an air-supply temperature of 292 K and an airflow rate of 1.2Q, although under such condition the Ozone concentration was still higher than the standard value required. What’s more, a few more important conclusions were obtained.(1) With different air supply, the air temperature and ozone concentration distribution trends are the same. But the average temperature and the average ozone concentration decreased with the increase of air supply.And with the increase of the air quantity, both ofthem the reduction rate is firstly increased and then decreased.(2) The air temperature and Ozone concentration increased as the air-supply temperature increased.(3) The energy consumption under different airflow rates and air-supply temperatures was analyzed by Design Builder. The results showed that there was a similar energy consumption between the condition when air-supply temperature was 291 K and airflow rate was Q and the condition when air-supply temperature was 292 k and airflow rate was 1.1Q or 1.2Q. Similarly, the energy consumption under the condition when air-supply temperature was 291 K and airflow rate was 1.2Q approximated the energy consumption under the condition when the air-supply temperature was 292 K and airflow rate was 1.4Q.(4) Considering all the results above, the best air-conditioning design parameters for the plant were proved to be an air-supply temperature of 292 K and an airflow rate of 1.2Q.Finally, the experimental measurements were carried out in a high welding plant in Changchun, to verify the authenticity of the CFD numerical simulation. By comparing the data of the measurement and the numerical simulation, the result showed that the data of the simulation was found to be within the error range, which suggested that the results of the numerical simulation could be trusted, and further proved that the authenticity of the CFD method in the energy conservation design of the high industrial plant.