288 publications from this institution
The interaction between solar chimney and wind was investigated numerically and theoretically. A higher wind velocity does not represent a better performance, which depends on wind angle (α), which is the angle between wind direction and outward normal of the wall with the window. A windward situation (0 degrees ≤α<90degrees) is suggested, where the scenario with α=0 shows the best performance. It is surprising that the leeward scenario with α=180 degrees presents a slightly positive effect, but scenarios with 90≤α<180 degrees show negative effects. Window area (A w) presents a positive effect on the airflow rate, which shows a linear relationship with A w 0.34 and A w 0.46 when the α is 0 and 45 degrees, respectively. A theoretical model was developed to predict the airflow rate under α<90 degrees, where for 90 degrees ≤α<180 degrees the related predictions can be based on the scenario without wind. The predictions are fitting quite well with numerical results. Critical wind velocity was also proposed to represent the wind velocity which overrules the performance that solar chimney is no longer dependent on solar radiation but wind. The critical wind velocity keeps increasing under higher solar radiation, where for the analyzed model it increases from 0.65 to 1.55m/s when solar radiation rises from 100 to 1300W/m2.
The diaphragm compressor is the essential component of a hydrogen refueling station, but the traditional design method results in low cavity volumetric efficiency and high refilling oil pressure. This study proposes a design method using a free moving oil piston to optimize the cavity volume. This method allows the cavity volume to be utilized to the maximum, and a “zero pressure” stage occurs at the end of the suction process, which greatly improves the cavity volumetric efficiency and reduces the refilling oil pressure. To further examine and verify the superiority of this method, 90 MPa and 200 MPa diaphragm compressors were designed and produced for comparison, and their simulation study was conducted simultaneously. The results demonstrate that this proposed design method can raise the cavity volumetric efficiency of the 90 MPa diaphragm compressor in the experimental case from 0.37 to 0.66. Additionally, the benefit increases with the compressor pressure. For the case of a 200 MPa diaphragm compressor, the cavity volumetric efficiency increases from 0.19 to 0.64.
