Characteristic Of The Respiratory Pump Employed In The Small-sized Ammonia-water Absorption Refrigeration System

In the small-sized ammonia-water absorption refrigeration system, asolution pump with high-head, small flow capacity, high stability and noleakage was needed. Generally, hydraulic diaphragm pump was choosed.But its efficiency is so low that the power performance of the system is low.In order to solve this problem, the new pumping technology which is calledrespiratory pump was put forward in this paper. In respiratory pump,ammonia-water strong solution could be delivered into generator by theammonia generated in the same refrigeration system. In this paper, theresearch on the respiratory pump could be summerized as follows.In the first part of this paper, the working principle and workingprocess of the respiratory pump was introduced. A working cycle of therespiratory pump was divided into two stages to discuss. The variation of thepressure, liquid level and the inlet/outlet flow rates of three differentcylinders in each stage were investigated. Then, the equations for the designcalculation of the respiratory pump and the ammonia loss calculation of thesystem were given in the paper.In the second part of the paper, the absorption phenomena in the secondcylinder of the respiratory pump was attributed to the heat and mass transferproblem during the ammonia vapor absorption into static ammonia-watersolution under big pressure differentials. The numerical simulation researchon this problem was carried out in this chapter. The physical and mathematical models of the absorption process with heat and mass transfercoupling in were established. When the ammonia pressure was a constantvalue, this model could be simplified into a half infinite, one dimensionalunsteady heat and mass transfer problem under the first boundary condition,and the analytical solution could be obtained. Based on the analyticalsolution, the relationship between surface mass transfer criteria and initialpressure difference was investigated And the semi-empirical correlationswas also carried out including the surface mass transfer criteria, initialpressure differential and initial parameters of the ammonia solution.Finally, the design principle and the design results of the respiratorypump were showed in this paper. The results included the size of therespiratory pump, time of each working stage and system ammonia loss.And evaluation of the respiratory pump was carried out from two aspects:performance and economy. The performance parameters of the respiratorypump was defined, and were compared with that of the electric pumps.Theresult indicated that: the efficiency of respiratory pump is higher.Comparing the ammonia-water refrigeration cycle emplyed the electricpump with the ammonia-water refrigeration cycle emplyed the respiratorypump, the result shows that: the power COP of the cycle emplyed therespiratory pump is higher. Especially, the respiratory pump was driven byammonia generated in the refrigeration system. So the respiratory pumpcould be regarded as driven by low temperature heat source. The using ofenergy of low taste, not relying on electrical energy made theammonia-water refrigeration cycle employed the respiratory pump wasbetter.