| Nowadays, along with the increase of the world population and the development of the economy, the energy requirement increases rapidly. The shortage of energy source has be one of the urgent problems. Another problem is the substitute of CFC which has aroused the depletion of the ozone and the other effects such as"greenhouse effect". More attention has been paid to the absorption cycle since the absorption system can be driven by wasted hot water or other heat sources and does not have the problem of the substitute of CFC. As one kind of absorption cycles, the diffusion absorption refrigerator uses the auxiliary gas to equalize the pressures throughout the system. Compared with the gas-compressed system, the diffusion- absorption cycle has no moving part and the associated noise and vibration as the ability to operate without any electric input.Based on the search of the literature dealing with the diffusion-absorption refrigeration technology, this article makes a study on a domestic-made ammonia-hydrogen small-sized diffusion-absorption refrigerator theoretically and experimentally. For the diffusion-absorption refrigerator, the theoretical cycle is analyzed and of the thermodynamic parameters of the system is calculated. Simultaneously with the theoretical analysis, the diagram of performance curve and diagram of temperature rise curve are made.An experimental platform for the measuring of the performance of the refrigerator is built in this work, and a refrigeration chamber with good seal and heat-insulation is made. The testing of the actual working performance is made for a small-sized diffusion-absorption refrigerator. The influence of the heating power on the performance and the influence of the heating load on the refrigeration temperature are analyzed by measuring data of the heating power, and core spending temperatures. The research demonstrates that the refrigerator will work normally on the input heating power between 25-42.5W, and the best input powers are between 28-35W. When the input powers are lower or higher than the best input power, the performance of the refrigerator turns bad dramatically, this illustrates that the effective working range of the diffusion-absorption refrigerator is quite narrow. Within 25-31W, the refrigerating capacity increases with the increasing of heating power. Within 32-42.5W, the refrigerating capacity decreases with the increase of heating power, The maximum effective refrigerating load is 6.4W on the refrigeration temperature below 10℃, of which the COP is 0.21. The commencing temperature is about 180℃, which is basically constant and will not vary with the heating power, which illustrates that the heating source power below 180℃will not activate the refrigerator.Analysis is also made of the principle of the diffusion-absorb refrigerator and the structures of its components, and the thermal parameters of each component are calculated in terms of thermo dynamical analysis. Based on the theoretical analysis, the mathematic model of each component is established, the calculating program is made and the influence of the concentration of the ammonia and the condensing temperature on the COP of the refrigerator are calculated. Within certain concentration range, the increase of the concentration of the ammonia will give a rise of refrigeration efficiency COP a small margin. The rise of condensing temperature will also give rise to the increase... |
