The solar air collector (SAC) is one of the key technologies for heating rural residences, but the current flat-plate solar air collectors (FSAC) have a limited heat collection, and the performance optimization methods for SACs are inadequate. In this study, a novel triangular solar air collector (TSAC) is presented, and based on the optical model and dynamic heat transfer model, a parallel gradient ascent algorithm is proposed for its performance optimization. With the maximum heat collection during the heating season as the objective function, the TSAC sides material and the inclination angle of the absorber are optimized within a determined range of the collector width and the inclination angle of the front transparent cover. The performance improvement of the TSAC before and after optimization is analyzed, and the applicability of the optimized TSAC is compared with traditional FSAC in different climate and solar resource regions. The results indicate that the heat collection of the optimized TSAC increased by 19.2% and the operating time added 106 hours during the heating season. The heat collection of TSAC has an advantage compared to FSAC in different regions, with an average increase of 18.1%.
In this study, a composite double-layer wallboard with shape-stabilized phase change humidity control materials (PCHCM) has been proposed for building usage. This novel PCHCM can absorb/release both heat and moisture to moderate indoor hygrothermal environment. Based on a numerical analysis in an office building in Wuhan (30.52°N, 114.32°E), China, the effects of PCHCM on both building energy consumption and indoor hygrothermal environment has been investigated. Firstly, a simulation model has been developed for the building integrated with PCHCM wallboards in EnergyPlus, combining both heat and moisture transfer finite solution algorithms. After a validation of the model, both heat and moisture transfer characteristics of the proposed composite wallboards were simulated, and its effects on indoor temperature, humidity and building energy consumption were analyzed. The simulation results showed that this novel PCHCM wallboard can effectively improve indoor hygrothermal environment, with reduced energy consumption by about 8.3% in summer and 24.9% in winter, comparing to the actually used materials in the case study building.
Drilling operation in TABNAK and SHAN-UL gas field drilled by S E Great Wall Drilling Co. of CNPC is very difficult. Its key drilling difficulties are how to overcome low pressure fractured reservoir leakage in long section of large hole, water - sensitive mud shale caving and high pressure salt water bearing reservoir. In the two gas fields, target well depth is about 3500m. In order to isolate complex formation, five different size casing have been run in, the biggest hole diameter is 914. 4mm, and the biggest outside casing diameter is 762mm. To improve penetration speed and shorten drilling cycle, using air/ foam drilling technique has obtained success. The paper presents the application of air/ foam drilling technique in TABNAK and SHANUL gas field.
A comfortable sleeping environment can improve sleep quality. Electric fans are widely accepted as an effective method in South China to improve the thermal environment in summer when people are sleeping. To determine the proper fan control strategy under the all-night blowing mode, pre-sleep and during-sleep experiments were performed in a climate room. Under 6 operating conditions (28/30/32 °C, 50%/80% RH), subjective sensation (thermal sensation votes and sleep quality indexes) were recorded and objective physiological parameters (brain waves and skin temperature) were monitored. The results show that the comfortable air speed interval before sleep is 0.15–1.44 m/s. The skin temperature showed a clear trend of first rising, then falling, stabilising, rising again, and finally rising with fluctuations throughout the night. Based on the characteristics of physiological parameters in different sleep periods, the sleeping time was divided into 5 stages to perform linear regression, and a dynamic air supply control strategy for fans that imitates the circadian rhythm of sleep was proposed. Compared with steady-state blowing, the sleep efficiency and proportion of deep sleep under this optimisation control strategy increased by 3.24% and 3.59%, respectively. This study provides a reference for fan control in a sleep environment.
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