基于光伏光热的地下空间太阳能烟囱效应影响因素研究

提出了将太阳能烟囱效应与太阳能光伏光热(PV/T)技术相结合来强化地下空间通风的技术措施.为研究该通风模式的影响因素,基于质量和热量平衡理论,建立了风井通风性能的数学模型,分析了换热器管排数、风井高度、热水水温和流速对通风性能的影响.结果表明:风井内换热器存在最大有效管排,管间距为0.032、0.038、0.047 m时换热器的最大有效管排数分别为9、13、18,在有效管排数范围内,随着管排数的增加风井出口温度升高,通风量先增大后减小;空气质量流量随着风井高度增加、热水温度升高明显增大,随着热水流速增大而缓慢增大;风井出口空气温度随着风井高度增加而降低,随着热水温度升高、流速增大而升高.最后,通过拟合得到计算风井空气质量流量的经验公式.

Study on influencing factor of solar chimney effect in underground space based on photovoltaic-thermal

Abstract: Pollutants are easy to be concentrated in the underground space because of the low terrain and the enclosure space. Therefore, an effective ventilation system is required to create a clean indoor environment. Ventilation fan is widely used in the underground space, but the fan has high energy consumption and is very noisy. Thus, both energy conservation and environmental protection are significantly important for the design of ventilation system, and solar chimney is a feasible method by using solar energy in order to realize these 2 purposes. Due to the special underground space environment, it''s impossible to construct a solar chimney as the ground building, which must be combined with other technologies. PV (photovoltaic) technology is a common solar energy utilization technology, but most of solar energy irradiating on PV cells is converted into heat when it is operating, resulting in a rising PV temperature and a dropping photoelectric conversion efficiency. In this project, photovoltaic-thermal technology is used to recover the heat of PV cells to maintain a high photoelectric conversion efficiency. This paper proposes a system combining the solar chimney effect with the photovoltaic-thermal technology for the purpose of enhancing the natural ventilation in the underground space. On one hand, this system can maintain the PV temperature at a high photoelectric conversion efficiency. On the other hand, the extra heat can be used in the underground space ventilation. Therefore, the ventilation energy consumption is reduced and the comprehensive utilization efficiency of solar energy is increased. To study the influencing factors of the ventilation system, a mathematical model for evaluating the ventilation performance of the ventilation shaft is established based on the conservation of energy and mass, which is solved by MATLAB software. The influences of heat exchanger tube row, height of ventilation shaft, water temperature and velocity on the ventilation performance are analyzed. Results show that the heat exchanger has a maximum effective tube row in each case, and the tube pitches of 0.032, 0.038 and 0.047 m correspond to the maximum effective tube rows of 9, 13, and 18, respectively. The outlet air temperature increases with the tube row, while the air mass flow rate increases and then decreases with the tube row. The air mass flow rate obviously increases with the height of ventilation shaft and the inlet water temperature, while it slowly increases with the water velocity. The outlet air temperature decreases with the height of ventilation shaft and increases with the water temperature and the water velocity. Finally, an empirical formula for calculating the air mass flow rate is fitted.