| Adsorption cooling cycle as an environmentally friendly method to refrigeration has become the focus of researchers at home and abroad. It is driven by the low-grade heat source, which enhances the quality of energy and reduces heat pollution of the environment. Silica gel-water adsorption chiller is generally used when the heat source is under 100 ℃. This chiller is characterized as large system, long cycle time and performance influenced by ambient temperature because of the small adsorption working pair cycle, which leads to its limited application. Therefore, in this thesis, suitable adsorbent was selected and its performance was tested. Then, the performance of adsorption chiller was tested. Finally the exergy efficiency and economy of the system were analyzed, trying to achieve the adsorption refrigeration system miniaturization and improve its performance.Firstly, four kinds of adsorbents were screened at the driven temperature of 60-90℃. Among them, A type silica gel and synthetic zeolite functional adsorbent material Z01 (FAM Z01) have better performance on the cycle effective amount of water adsorption. Then these two adsorbents were tested to compare the cycle effective amount of water adsorption in the adsorption chiller at actual operating pressure (desorption at 70 ℃ and adsorption at 30℃). The result shows that the cycle effective amount of water adsorption of the FAM Z01 is 2.6 times larger than the A type silica gel, reflecting high efficiency of the FAM Z01 adsorbent material and providing possibility to refrigeration system miniaturization in the near future.Then, the adsorption chiller of adsorbent FAM Z01 was built, the structure and types of the main parts of which, including coated adsorbent bed, spray type evaporator, shell and tube condenser, were determined. The cooling capacity of adsorption chiller system was 10kW, and the results of stability test show that the system had good stability, strong repeatability and short cycle time.Finally, the performance of the adsorption chiller was tested, and it is found that the chiller could produce 2.3-4.5kW cooling power, driven by the heat resource at 55℃, which is lower than silica gel system driven temperature. The performance of the adsorption chiller plays to its strengths under driven temperature of 65 ℃, whose average cooling power and COP reach to 8.2kW and 0.43, respectively. The adsorption chiller was tested in different cooling water temperature. The results show that ambient temperature has little influence on the performance of the adsorption chiller. The performance of the adsorption chiller at different heat source and chilled water flow rate was further investigated. It is found the performance of the system is improved by the increase of heat source and chilled water flow rate, but the increase is less and less. Therefore, considering the power of circulating water pump, the system should operate at the appropriate flow rate range to reflect its economy.In addition, this thesis also analyzed the thermal process of the system, and compared its exergy efficiency with the mature technology of compression refrigeration. It is found that the adsorption refrigeration COP is relatively low, but its exergy efficiency is higher than the mechanical compression refrigeration. Finally, economy of the system was also analyzed comparing to mechanical compression refrigeration. Although the adsorption refrigeration system is more expensive and requires long recovery period, it is believed that, with the development of technology, the application of adsorption refrigeration has a broad prospect. |
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