The energy-saving reconstruction for the existing building is very important for the large number of existing buildings in China. The energy-saving reconstruction in the roof is the key of the building energy-saving construction, and also the inevitable way for improving the urban heat island effect and comfort of the top-floor rooms. The energy-saving roof can be divided into two types including passive cooling and proactive cooling. This article analyzes the advantages and disadvantages of the two types before coming up with the ways and expectation for the energy-saving construction of the existing building roof.
This paper mainly analyzes the high efficiency characteristic of cross-critical carbon dioxide cycle refrigeration, especially when this refrigeration system works as a heat pump. When this refrigeration system is used as heat recycle system with larger different temperature and high level temperature, the solely superiority and energy saving capability of this system will reveal. However, the development localization of cross-critical CO2 cycle refrigeration system also exists, which includes immature cross-critical CO2 flow and heat exchange theory, and seal problem of compressor, expansion ratio of expansion equipment.
The surface of the wafer is easy to be polluted by the organic pollution material. The supercritical fluid extraction technology works well in extracting organic pollution material. Whether the extraction process influences the surface performance of the wafer can be determined through the SEM(scanning electron microscope), AFM (atomic force microscope), and XPS (X-ray photoelectron spectroscopy). Compare the feature and the electronic structure of the wafer before and after supercritical CO2 extraction to get how supercritical CO2 extraction process influences the wafer surface performance. The conclusion helps to determine whether the extraction technology can be applied in the wafer surface cleaning technology. Tests show that supercritical CO2 extraction process almost does not influence the surface performance of the wafer, and, the supercritical CO2 extraction technology has a good prospect in the wafer cleaning.
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