The Characteristic Research On LiBr Aqueous Solution Absorption Heat Pump Unit By Using Multiphase Additives

The paper is based on a self-made lithium bromide absorption heat pump units as thebasic research bench.The modified unit was to be become supercharged absorption heat pumpunit.The unit is respectively filled with industrial pure lithium bromide solution,added solidnano-particlesof lithium bromide solution and added surfactants of nano-particles lithiumbromide solution.Under the changing working conditions of changing environmentaltemperature,the unit carried the conventional working conditions for operation andsupercharging heat pump operation of the non-equilibrium state. The test data were picked upand analysised theoretically,and theperformance of absorption heat pump unit under theconditions of each state was studied.The specific research results are as follows:Based on the thermal physical property parameters calculation formula of the lithiumbromide aqueous solution and equations of equilibrium of the lithium bromide aqueoussolution from American Society of Heating Refrigerating and Airconditioning Engineer(ASHRAE), an accurate calculation method of determining the thermal physical parametersof the lithium bromide aqueous solution was obtained by simulation calculation.From thecomparison result when the temperature and the concentration of the lithium bromide solutionis known, the average error between programming simulation calculation results with theexperimental measured results is4.21%, high precision. To simulate the single effect cycle ofheat pump and visualize this method with VB programming language can forecast andanalyze the performance of the unit.Added Nano-particles and surface active agent inlithium bromide aqueous solution canreduce solution surface tension and boiling temperature. The reduction of surface tension willpromote solution mass and heat transfer; the decrease of boiling temperature is advantageousfor dilute solution to parser vapour in the generator.This paper mainly studies the influence ofexternal parameters in different filling solutions (Pure lithium bromide aqueous solution,nano-particles lithium bromide aqueous solution andnano-particles lithium bromide aqueoussolution with surfaceactiveagent added), such as, the adjustment of evaporation temperatureand hot water outlet temperature, apply variable-operatingconditions. Analysis of theexperimental results showed that：1.Nano-particles was added in the lithium bromide aqueous solution to strengthen theabsorption effect and reduce the generating temperature. Improved the absorption heat pumpunit performancegreatly. The heating load increases by7.71%, the low temperature heatsource heat absorption capacity increases by21.86%, the heating coefficient increases by3.68%.2.Surface active agent is added in the nano-paticles lithium bromide aqueous solution. Nano-particles and surfactant work together to further improve the absorption heat pump unitperformance.The heatingload increases by18.26%, the low temperature heat source heatabsorption capacity increases by32.99%, the heating coefficient increases by2.57%.Nano-particles and surface active agent working together ismore efficient to improvethe heating load and low temperature heat source heat absorption capacity.3.In pressurization absorption heat pump unit performance test, strengthen the absorptioneffect is obvious.The absorber pressure is pressurized from5.5kPa to6.5kPa.Using purelithium bromide aqueous solution absorption heat pump unit, the heatingload increases by24.95%, the low temperature heat source heat absorption capacity increases by86.27%; Usingthe nano-particles lithium bromide aqueous solution absorption heating pump unit, theheatingload increases by58.43%, the low temperature heat source heat absorption capacityincreases by134.55%; Use added surfactants of nano-particles lithium bromide aqueoussolution absorption heat pump unit，the heatingload increases by41.47%, the low temperatureheat source heat absorption capacity increases by111.02%;.Heating coefficient of initial stagehas improved greatly. But as a result of absorption heat pump unit parts design load isset.Heating load reaches limit, the unit performance coefficient also appears extremum whenthe steam pressure increases to a certain value(5.7kPa). But after added nano-particles andsurfactant, the thermal properties of lithium bromide solution changes, raises the limit load ofeach heat exchanger unit.The coefficient of heat supply falls slowly than pure lithium bromidesolution.