Publications

Compared to previous theoretical analysis of naturally ventilated double-skin façade (NVDSF), still in scarcity is a model that can reflect the coupling mechanism of radiation and natural convection, meanwhile being readily calculable to save from excessive numerical computing. Therefore, this study proposes a new theoretical model for an NVDSF that addresses its thermal and ventilation performance under varying environmental conditions. The theoretical analysis of energy balance and buoyancy flow is deepened by additional numerical modelling that reveals features of the coupled heat transfer and fluid flow. Key correlations between radiation and natural convection obtained from simulation data assisted in establishing an explicit solution of glazing temperatures, which are consequently used to moderate the fully mixed model for obtaining the natural ventilation rate. Eventually, the new theoretical model is featured with a more accurate evaluation of channel natural convection and straightforward calculation of temperature and flow rates in response to external conditions. In addition, an example performed over a daily condition demonstrates the capability of the theoretical model to replace time-consuming numerical simulations over transient changes. The in-depth understanding of the solar-assisted natural ventilation mechanisms revealed by this model can contribute mainly to facilitating similar passive energy-saving techniques that involve solar radiation absorption in glazing materials.

A novel rectangular energy storage unit (RTESU) is proposed to effectively harvest low-radiant solar energy in poor solar areas for the application of preheating cold outdoor air. The RTESU consists of tube bundles to charge phase change material (PCM), paraffin wax PCM panels and air channels to discharge heat to cold outdoor air. Experiments on the charging and discharging processes with heat transfer fluid (HTF) temperature (varying from 28 to 36℃) and flow rate (varying from 0.96 to 2.04 m3/h) are performed to investigate the thermal performance of the device for poor solar areas. PCM temperature variations, heat transfer characteristics, heating capacity, and melting and solidification dynamics are analyzed. The results reveal that solar energy can be harvested and stored in PCM through melting process even under extremely poor solar radiation (about 138.68 W/m2) within 3.6 h. During the charging process, the natural convection plays a dominant role, while conduction is dominating throughout the discharging process. Further analysis of the thermal performance of discharging process shows that the heat extraction effectiveness can be improved as the air inlet temperature decreases. The highest heat extraction effectiveness can approach 100% in 10.2 h when the air inlet temperature ranges from 11.5 to 13 °C.

Silicon Carbide (SiC) aerogel is a material with 3D network structure, low density, and high-temperature resistance, showing a broad application potential in various areas. It is currently challenging for SiC aerogels to balance the mechanical and high-temperature insulation properties. Here, a novel strategy was implemented for the first time, by constructing coaxial precursors. This structure can achieve in-situ Si-C binding and maximization the reaction sites to achieve fibers growth uniformly. The sintering time is reduced by over 90%. The fatigue resistance and elastic properties of the SiC aerogel were significantly improved. In addition, the uniform nanowire fiber and pore structure enable an ultra-low thermal conductivity of 0.018 W/(m K) at room temperature, 0.082 W/(m K) even at 900 °C, and superior structural stability at 1400 °C. Our strategy provides a feasible approach for the structural design of thermally insulated SiC aerogels with high elastic resilience and good adsorbability.

Previous studies have focused on the horizontal buried pipe section regarding the performance improvement of the earth-to-air heat exchanger, showing limited attention paid to the vertical air inlet section. In this study, we proposed a novel earth-to-air heat exchange system utilising an inlet plenum chamber (IPC-EAHE) to pre-treat the outdoor air in the inlet section. To evaluate its cooling performance, a numerical model was developed and validated based on a field experiment. The results showed a good agreement between simulated and experimental data, with a maximum absolute relative error of 4.43 % for the outlet air temperature. Then comparative studies between the IPC-EAHE and traditional EAHE are conducted under three airflow rates. Results indicated that the IPC-EAHE has a lower and more stable outlet air temperature than traditional EAHE. Compared to the traditional EAHE, the IPC-EAHE reduces the fluctuation of outlet air temperature by 53.13 %, 29.84 %, and 26.60 % under the airflow rates of 190 m3/h, 380 m3/h, and 570 m3/h, respectively. This improves the free cooling potential of EAHE for buildings. Moreover, the IPC-EAHE can reduce the buried pipe length by around 60.30 %, 53.0 %, and 50.0 % for three airflow rates, respectively. The friction resistance loss of the IPC section is at least 20 % less than that of the traditional EAHE vertical inlet section. The above results demonstrate that the IPC-EAHE offers greater renewable energy utilization efficiency and less buried pipe length than the traditional EAHE.

Naturally ventilated double-skin façade is the biggest heat and mass transfer interface between indoor and outdoor environments, identified as one of the weakest energy components in buildings. As controlling naturally ventilated double-skin façades is significant to improve its energy performance, a critical review was then undertaken on this, including passive (e.g., materials), manual (e.g., blinds), active (e.g., air-conditioner), non-automatic hybrid (e.g., passive-active systems), and automatic (e.g., automatic-windows) control systems. Based on the reviewed studies, the annual energy-saving performance of those control systems was obtained and analyzed. The energy-saving performance in descending order is the hybrid, passive, automatic, active, and manual control system, achieving an average annual energy saving of 47.9 %, 36.7 %, 32.1 %, 32 %, and 27.3 %, respectively; while their estimated initial costs in descending order is the automatic, hybrid, active, manual, and passive control system, respectively. Based on their energy-saving performances and initial costs, hybrid control systems can be adopted under those scenarios with high energy-saving requirements, passive control systems are a good balance of energy-saving performance and initial costs, and automatic control systems apply to those scenarios with highly required thermal comfort under obviously changing local weather. An optimal control system achieving the most average annual energy-saving varies in different climate zones. In tropical climate zones, the optimal control system is the passive control system; in subtropical and temperate climate zones, the optimal system is the hybrid control system. This review serves a vital guide on selecting and optimizing DSF controlling systems in buildings under various climate zones.

Sealing tunnel portals is an important approach to control tunnel fires. The maximum gas temperature rise beneath the ceiling was studied under the effects of both fire location and size in a portals-sealed tunnel model. Previous studies showed that the maximum gas temperature rise decreases when fire source is away from the tunnel center, companied with increasing flame inclination angle. In this study, based on dimensional analysis, an empirical model was developed to predict the maximum gas temperature rise beneath the ceiling in a portals-sealed tunnel. It is known that this model can provide reasonably good predictions to different fire scenarios considering fire location and size. A 3/4-power relationship was shown between maximum gas temperature rise and dimensionless fire size, while the normalized maximum gas temperature rise follows an attenuation law of e - φ with the fire location. The focus of the study is more of an academic nature than practical. This is an academic study with pioneering character, which in future may be solved in a more practical way than presented here. However, the outcomes from this study can provide a better understanding for the fire behavior in the portals-sealed tunnel fires and credible prediction about maximum gas temperature under related fire scenarios.

Using a double-skin facade for natural ventilation is not a new idea, but the behind mechanism and impacts of those environmental and designing factors on its performance are still unknown and critically needed. Therefore, through this study, the influences of the façade and room configurations, together with the environmental factor on buoyant-driven natural ventilation, are addressed. An experimentally validated numerical model has been adopted to analyse the airflow characteristics inside the NVDSF and the room caused by combined radiation and natural convection. Results reveal that the primary influence comes from the dimensions of NVDSF, followed by the size of window openings. For the analysed NVDSF, an optimal gap depth is found at 0.2 m, and an optimal vent height is around 0.2–0.3 m. More gap depths result in more counterflows at the top, while a taller vent unnecessarily weakens the heat transfer. Besides, influences from room/window configurations also cannot be overlooked. Windows on the sidewall are found to deliver better indoor airflow coverage, although it gives around 2.5% less ventilation rate. Compared to a ‘no room’ condition (i.e., all the openings of the NVDSF are directly connected with outdoor but not room), our models with room only achieved 85–93% of the airflow rate depending on window sizes. It highlights the importance of considering room and windows for an accurate and practical assessment. Although the window locations and room dimensions draw minor impacts on the ventilation rates, the changes in airflow distribution prove their own importance in terms of air quality assessment.

In this study, we showcase the application of X-ray radiation therapy of tumor-bearing mice across 13 syngeneic tumors, one intracranial tumor, and in combination with radiosensitizing drugs, aiming to develop potent cancer treatment strategies. 1.We examined the effects of different radiation levels on multiple tumor models using a therapeutic device delivering targeted radiation to the tumor site. 2.We investigated the combined benefits of radiation with the radiosensitizer Gemcitabine on the H22 liver tumor model. 3.We assessed the impact of radiation sensitization on the HCC1975-luc intracranial tumor model in combination with AZD0156, a drug that cannot cross the blood-brain barrier. The integrity of the blood-brain barrier and the presence of the pharmacodynamic marker pRAD50 of AZD0156 were evaluated. The results show that X-ray radiation has anti-tumor effects across diverse models, with combination drug treatment with both Gemcitabine and AZD0156 showing enhanced therapeutic effects. Furthermore, pRAD50 showed decreasing trend in the single dose PD study in HCC1975-luc intracranial model. We conclude that our platform provides robust methods for evaluating the therapeutic effects of X-Ray radiation, offering invaluable insights for the creation of new cancer therapies. Citation Format: Jingqi Huang, Wentao Li, Xiaoyan He, Weiwei Cheng, Lingyun Zhang, Guannan Li, Qiuliang Li, Yongfei Wang, Xuesong Ren, Zhi Wei, Long Shi, Yiran Wei, Jing Jin, Linfeng Li, Wei Yun. A multifaceted study of X-Ray radiation therapy across diverse mouse tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1129.

Although the angular dependence of optical properties has long been recognised in transparent glazing facades, the impact of such dependence on natural ventilation between glazing has not been widely studied, especially in building facades with high solar incident angles. To better cope with such properties with the prevailing implementation of transparent building envelopes, this study investigated the effects of high solar incidence angles for vertical building facades through theoretical and numerical methods. The theoretical model validates the features of the optical properties simulated by the numerical model, supporting the numerical model's capability of revealing the radiation reflection, absorption, and transmission when multi-reflection is present. Then, such angular impact is studied with typical seasonal data in three cities, namely Shanghai, Melbourne and Chicago. Results firstly revealed the discrepancies between considering or ignoring multi-reflection between two glazing facades at varying incidence angles. Due to the opposite variation trend in reflectivity and transmissivity over angles, there is a critical solar incidence angle at 75° when multi-reflection's impact on natural ventilation reaches its highest. After that, the influence is reduced to its minimum. Identifying this angle helped highlight the enhanced natural flow due to realistic angular-dependent reflections between transparent panes, namely, under-estimation occurs if the angular dependence is not considered in the setting of optical properties. The analysis in three cities also revealed the climatic and locational impact of the angular impacts on ventilation rates. By addressing the impact on the optical and thermal performance of transparent facades, the dynamic variation of solar conditions can be more accurately integrated into passive building designs.

Upholstered furniture usually has a typical two-layer structure with an ultra-thin surface layer. The surface layer can significantly affect the overall fire behaviors of the upholstered furniture. A series of experiments were carried out to investigate the fire behaviors of six two-layer combustibles based on a cone calorimeter. An empirical model was proposed to predict the heat release rate of two-layer combustibles. The predictions of the model are fitting quite well with experimental data. It was also known that the ignition time of the two-layer combustis dbles is controlled by those surface fabric materials. The shrink rate and the properties of the residues of those surface fabrics show obvious influences on the combustion processes. Comparing to those uncovered natural latex foam samples, it was known that the peak heat release rate decreases about 26.9% and 11.7% for the samples with natural and synthetic species covers, respectively; and the duration of the burning process increases about 41.7% and 15.4%, respectively. A combustion factor was proposed and a heat transfer model was developed to reflect the contribution of the surface and the second layers to the combustion processes. The combustion factor is within 0.7-0.9 for the six types of surface fabrics.

Post-fire-curing is an effective method to recover fire-damaged concrete. In order to investigate the effects of cement dosage and cooling regimes on the recovery of fire-damaged concrete, three kinds of concrete specimens, with different cement dosages of 412, 392, 372kg/m3, were prepared and tested. After cooling either in a furnace or ambient environment to the room temperature, these specimens were first soaked in water for 24h and then subjected to 29days’ post-fire-curing. Based on temperature history, residual compressive strength and cracks in the cross sections were tested and analyzed. And scanning electronic microscope (SEM) was used to help the morphology analysis. A new parameter named heat accumulation factor was proposed to estimate the strength loss and the recovery potency of the fire-damaged concrete. It was known from the experiments that the difference of relative residual compressive strength of specimens with three cement dosages is less than 3 percentage points. After post-fire-curing, the relative residual compressive strength of the specimens cooled in the air recovered from 77% to 83%, while that of the specimens cooled in the furnace recovered from 65% to 87%. The longer exposure under high-temperature due to the cooling in the furnace was responsible for the lower relative residual compressive strength and higher recovered strength. This is because the high temperature can promote dehydration processes, accompanied with more rehydration products with a denser microstructure. The crack lengths were observed much longer in the specimens cooled in the ambient environment due to the higher temperature gradient during the cooling process. The higher temperature and temperature gradient near the surface can result in more intensive cracks.