Study Of Coupling Characteristics Of Double-Stage Bubble Pump With Lithium Bromide Refrigeration System

In the case of global energy shortage, conserve energy and further improve energy efficiency has become the focus problem and aroused the worldwide concerned. In the refrigeration industry, bubble pump absorption refrigeration has been obtained widespread concerned because consuming waste heat instead of electrical energy and mechanical energy. The coupling characteristics of double-stage bubble pump with lithium bromide refrigeration system were studied in this paper.Firstly, the lithium bromide solution thermal properties and mathematical models of main components were demonstrated in the paper for later chapter programming. Secondly, the design calculation of the double-stage bubble pump lithium bromide refrigeration system was carryed out, and the parameter values of each state point and main components heat load and heat transfer area and so on were obtained.And then the theoretical analysis was carryed out, and the results show that:1, The weak solution concentration increase and coefficient of performance (COP) of refrigeration system decrease as the inlet temperature of cooling water in others conditions unchanged. The inlet temperature of cooling water increase1℃and the COP will decrease2.8%-4.9%.2, The weak solution concentration decrease and COP of refrigeration system increase as the outlet temperature of chilled water under the condition of other factors constant. The outlet temperature of chilled water increase1℃and COP will improve3.6%-6.1%.3, Lithium bromide (LiBr) strong solution concentration increase will lead to the COP increase, but the increase rates slow.4, The outlet temperature difference of low pressure generator decrease as the concentration of LiBr strong solution, and the temperature difference, in generally, is controlled3-7℃, preferably not less than3℃, and at the same time, LiBr strong solution concentration is lower than64%.5, By orthogonal test analysis, the outlet temperature of chilled water and inlet temperature of cooling water and LiBr strong solution concentration have significant influence on the COP, and the degree of significance decrease sequentially.6, The first-stage refrigerant vapor flow increase as the heat input, and decrease as driving head and the bubble pump raising pipe diameter.7, The weak solution and intermediate solution flow increase as heat input, driving head and the bubble pump raising pipe diameter.8, The concentration of intermediate solution decrease as the bubble pump raising pipe diameter.Finally, the laboratory bench of double-stage bubble pump LiBr refrigeration system was set up, and experiments were carried out. Experimental results indicated that:1, Weak solution flow increase as the heat input and decrease as the cooling water flow.2, The first-stage refrigerant vapor flow increase as heat input and cooling water flow.3, The figures of first-stage refrigerant vapor flow and weak solution flow show that intermittent exists in the bubble pump LiBr refrigeration system, and the annular flow can make the system stable.4, The influence of heat input1740W on the system performance is significant when the LiBr solution concentration is53%. The influence from the structure size becomes not to be ignored when heat input exceeds1740W.5, The influence of condensation temperature on COP becomes less significant as the evaporation temperature.6, The influence of evaporation temperature on COP becomes significant as the condensation temperature.