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• The influences of the geometric parameters of the reactor on the SCPP-HPCR are investigated. • A formula is proposed to calculate the CO 2 emissions reduction of the system. • The optimal operating conditions of the SCPP-HPCR is analyzed. • 2.38 kg of CH 4 is degraded and 375.52 kg of CO 2 is reduced through the system one day. The increase of 1.09 °C in global temperature resulted in significant catastrophes because of the extreme climate. The climate change rate can be slowed down by reducing the levels of CH 4 and CO 2 in the atmosphere. The solar chimney power plant integrated with a honeycomb photocatalytic reactor (SCPP-HPCR) uses the photocatalytic technology to remove atmospheric CH 4. In addition, CO 2 emissions can be reduced from coal fired power plant due to the generating capacity of the system. In this paper, the influence of the geometric parameters of the reactor and turbine on the overall performance of the SCPP-HPCR is studied by numerical simulation. The obtained results showed that the flow resistance inside the system was mostly caused by the HPCR at low turbine speed, and primarily by the turbine at high turbine speed. Reducing the pore diameter of the reactor could improve the photocatalytic performance of the SCPP-HPCR more than increasing the turbine speed. The SCPP-HPCR having a pore diameter of 3 mm, porosity of 0.85, and constant turbine speed of 180 rpm, built in Qianyanzhou, China, could remove 2.38 kg of CH 4 and reduce 375.52 kg of CO 2 in one day. [ABSTRACT FROM AUTHOR]

• The concept of the SC in buildings coupling PCRs for atmosphere CH 4 removal was quantitively verified. • The effects of CH 4 degradation and indoor ventilation by the system were analyzed. • The photocatalytic efficiency, purification rate, and fresh air rate were analyzed. • The new system could degrade 57.27 μg/s of atmospheric CH 4 under optimal conditions. The techniques for the removal of methane from the atmosphere are highly challenging due to its stable chemical properties, dispersed sources, and low concentrations. This paper proposes a practical small-scale solar chimney (SC) in buildings with photocatalytic reactors (PCRs) for atmospheric methane removal. Two comprehensive numerical models on photocatalytic reaction and indoor ventilation are developed. The numerical simulation considers the performance of methane removal and indoor air ventilation of the proposed system, as well as its specific crucial parameters such as the type of PCRs, solar radiation, and flow channel width. The obtained results show that the SC with honeycomb photocatalytic reactor (HPCR) is more able to remove atmospheric methane than SC with plate photocatalytic reactor (PPCR) under the premise of meeting the ventilation standards. In addition, there is a maximum methane purification rate of 57.27 μg/s under the condition that the air gap width is 0.3 m, the length of the HPCR is 1.5 m, and the porosity is 0.85. It is then proved that the SC in buildings with PCRs can allow small-scale, zero-energy consumption, continuable, and decentralized low-concentration atmospheric methane removal while improving the indoor ventilation. [ABSTRACT FROM AUTHOR]

• The numerical simulation is used to validate the effectiveness of atmospheric methane removal by SCPP-PCR. • The performance and influencing factors of photocatalytic oxidation of methane by the SCPP-PCR were analyzed. • The photocatalytic efficiency and purification rate were introduced to evaluate the effect of SCPP-PCR on methane removal. • The optimum dimension of photocatalytic reactor with pore diameters of 2–4 mm was determined. Methane (CH 4) is the second largest contributor to global warming among all greenhouses gases. A solar chimney power plant integrated with a photocatalytic reactor (SCPP-PCR) is a promising large-scale method for removing CH 4 from the atmosphere. This study used computational fluid dynamics (CFD) to investigate the performance and factors influencing photocatalytic oxidation of methane by the SCPP-PCR system. The geometry of a SCPP is the same as the prototype of the SCPP built in Manzanares (Spain). The PCR is designed based on a honeycomb monolith photoreactor. The numerical results revealed that the SCPP-PCR system can degraded 21,312 g methane per day with the actual solar radiation data when the channel diameter of the honeycomb PCR was 4 mm and channel length was 8 m. Although increasing the length or decreasing the channel diameter of the PCR would improve photocatalytic efficiency, the rate of airflow of the system would be reduced. The maximum methane purification rate of the SCPP-PCR system was determined. [ABSTRACT FROM AUTHOR]