Research Of Double-Effect Lithium Bromide Absorption Cooling System Using Ejector As Absorber

Because of the thermodynamic property of lithium bromide-water solution, lithium bromide absorption cooling system has demand for the temperature of the heat source. Different modal of lithium bromide cooling system all has a lower limit of temperature of the heat source at definite surrounding temperature. If the temperature of heat source lowers than the minimum temperature, the system can't refrigerate. Besides the limit of minimum temperature of the heat source, the lithium bromide absorption cooling system also has a best range of the temperature of heat source. Just running at in the range, the system will be safe and efficient. If the temperature runs out the range, it must regulate the flux of the heat source for make the system working at the best situation.At rating running condition, the best range of heat source temperature of single-effect lithium bromide system is between 90℃to 115℃around, while the best heat source temperature of double-effect lithium bromide system is 155℃around, its efficiency depressed sharply when lower than the best heat source temperature, next to the efficiency of single-effect system. The temperature of first heat source of central heating system in our country is between 120 and 150℃, and utilization factor of the equipments and pipes lower than 50% for season. Make use of the first heat source of central heating system in lithium bromide system can increase its utilization factor, at the same time it can also decrease the electric energy of air-condition in summer. At definite condition, the lithium bromide absorption cooling system will save energy than vapor compressed refrigeration.This thesis does research about the singer-effect and double-effect lithium bromide absorption cooling system separately using the Fist law and second law of thermodynamics. For the lithium bromide absorption cooling system can use hot water of central heating system as heat source, add a vapor compress unit between evaporator and absorber in refrigeration battery to lower the demands for the temperature of heat source. The way to realize the effect of compress is using an ejector and a solution pump instead of the absorber, make the lithium bromide absorption system can work efficient at the temperature between 115°C to 130°C.From the point of the equilibrium of heat and quality transfer, this thesis sets up the mathematical model and common module of each part through Simulink toolbox. This thesis analyzed the lithium bromide of absorption and finders the factors affect the efficiency by calculate the loss of each part of the system. At the same time, this thesis compares the effect of the loss at each part to the efficiency.