Jet-pump crystallizers in reaction-crystallization processes with solid reagent–barium sulphate precipitation study

The research results concerning barium sulphate precipitation from the concentrated water solutions of barium chloride by means of crystalline ammonium sulphate addition are presented. The experiments were carried out in a continuous laboratory DTM crystallizer with inner circulation of suspension. A liquid jet-pump device generating ascending/descending flow of medium in a mixing chamber was used. Influences of barium chloride concentration in a feed solution (5–24 mass%), process temperature (303–348 K), mean residence time of suspension in a crystallizer working volume (600–10,800 s) and direction of circulation in jet-pump's mixing chamber on the resulting crystal size distribution of barium sulphate were investigated. Neural network models of the process were elaborated, providing the basis for the theoretical analysis of the influence of hydrodynamic regime on the population density distributions of crystal product. Conformity of the simulated population density distribution data with the experimental ones, as well as with the SDG kinetic model predictions was analyzed, verified and discussed.     

提高射流泵性能的途径研究

效率、噪声和运行寿命是射流泵的三个主要性能指标．本文依据大量原、模型试验结果，尤其通过对泵内水流流态的观察，分析了影响射流泵上述性能指标的若干因素和主要原因．认为：影响效率的主要因素是面积比，噪声主要来自于泵的尸重汽蚀，预防汽蚀、提高易损部件材质，可有效地延长泵的运行寿命．在为大寨、漫湾等电厂的供排水射流泵设计中采取相应措施，收到了较为良好的效果．为提高泵的性能指标、设计性能优良的射流泵探索了一条可供借鉴的途径．     

An alternative analysis applied to investigate the ejector performance used in R141b jet-pump refrigeration system

The system performance of R141b jet-pump refrigerator is discussed based on an alternative analysis. It explains the operation of the jet-pump refrigerator operating under actual conditions. A 2 kW cooling of R141b jet-pump refrigerator is designed and constructed to test the ejector performance. With the use of an alternative analysis, point of interest called “critical evaporator temperature” is determined. This point indicates the lowest possible evaporator temperature where the secondary fluid flow is still choked. The critical point varies with the change in operating conditions and with the primary nozzle used. An increase of primary mass flow rate causes the critical point reducing. However, it does not always true. When the primary mass flow rate increases to a certain value, the refrigerator is operated at higher critical evaporator temperature. Thus, the optimum range of the primary mass flow rate for this particular ejector is provided for this present work.     

Results of an experimental study of an advanced jet-pump refrigerator operating with R245fa

An experimental jet-pump refrigeration system was designed and constructed to assess the performance of R245fa (1,1,1,3,3-pentafluoropropane) as a suitable refrigerant. The paper describes and evaluates the results of experimental tests over a range of operating conditions. In addition, the effects of primary nozzle geometry on jet-pump performance are reported. Performance maps, useful for practical design and control are also provided. Experimental values of coefficient of performance (COP) between 0.25 and 0.7 were obtained. These results demonstrate that low-grade heat can be used to drive efficient jet-pump refrigeration systems, using R245fa as their working fluid, for high temperature applications, such air conditioning.