Influence of thermal flow field of cooling tower on recirculation ratio of a direct air-cooled system for a power plant

In order to get thermal flow field of direct air-cooled system,the hot water was supplied to the model of direct air-cooled condenser(ACC). The particle image velocimetery (PIV) experiments were carried out to get thermal flow field of a ACC under different conditions in low velocity wind tunnel,at the same time,the recirculation ratio at cooling tower was measured,so the relationship between flow field characteristics and recirculation ratio of cooling tower can be discussed. From the results we can see that the flow field configuration around cooling tower has great effects on average recirculation ratio under cooling tower. The eddy formed around cooling tower is a key reason that recirculation produces. The eddy intensity relates to velocity magnitude and direction angle,and the configuration of eddy lies on the geometry size of cooling tower. So changing the flow field configuration around cooling tower reasonably can decrease recirculation ratio under cooling tower,and heat dispel effect of ACC can also be improved.

New Way to Synthesize DW286——a Novel Fluoronaphthyridone Antibacterial Agent

A new route for the synthesis of DW286, 7-[3-（aminomethyl）-4-（methoxyimino）-3-methyltetrahy- dro-1H-1-pyrrolyl]-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydro[1,8]naphthyridine-3-carboxylic acid hydrochloric acid salt, is described. In the presence of benzadehyde, DW286 was prepared by the direct condensation of 7-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydro[1,8]naphthyridine-3-carboxylic acid with new pyrrolidine derivative 7 which could be obtained by routine reactions.

Enhancement of freshwater production of the seawater greenhouse condenser

Seawater greenhouse(SWGH)is a technology established to overcome issues related to open field cultivation in arid areas,such as the high ambient temperature and the shortage of freshwater.It adopts the humidification-dehumidification concept where evaporated moisture from a saline water source is condensed to produce freshwater within the greenhouse body.Various condenser designs are adopted to increase freshwater production in order to meet the irrigation demand.The aim of this study was to experimentally investigate the practicality of using the packed-type direct contact condenser in the SWGH to produce more freshwater at low costs,simple design and high efficiency,and to explore the impact of the manipulating six operational variables(inlet air temperature of the humidifier,air mass flowrate of the humidifier,inlet water temperature of the humidifier,water mass flowrate of the humidifier,inlet water temperature of the dehumidifier and water mass flowrate of the dehumidifier)on freshwater condensation rate.For this purpose,a direct contact condenser was designed and manufactured.Sixty-four full factorial experiments were conducted to study the effect of the six operational variables.Each variable was operated at two levels(high and low flowrate),and each experiment lasted for 10 min and followed by a 30-min waiting time.Results showed that freshwater production varied between 0.257 and 2.590 L for every 10 min.When using Minitab statistical software to investigate the significant variables that contributed to the maximum freshwater production,it was found that the inlet air temperature of the humidifier had the greatest influence,followed by the inlet water temperature of the humidifier;the former had a negative impact while the latter had a positive impact on freshwater production.The response optimizer tool revealed that the optimal combination of variables contributed to maximize freshwater production when all variables were in the high mode and the inlet air temperature of the humidifier was in the low mode.The comparison between the old plastic condenser and the new proposed direct contact condenser showed that the latter can produce 75.9 times more freshwater at the same condenser volume.

Study on heat transfer enhancement of discontinuous short wave finned flat tube

The typical configuration adopted by air-cooled condenser(ACC) in coal-fired power generating unit is the wave finned flat tube. The development of boundary layer between wave fins along long axis of flat tube can suppress the air-side heat transfer enhancement to a great extent. It has been proved that the serrated fins can enhance heat transfer obviously by breaking the development of boundary layer periodically. In the present study,the discontinuous short wave fin was introduced to the flat tube to enhance the air-side heat transfer of ACC. Two different types of arrangements,i.e. staggered and in-line for discontinuous short wave fins on the flat tube,were designed. By numerical simulation,the heat transfer and flow performances of short wave fins were studied under different arrangements(in-line,staggered) ,and the influences on heat transfer and flow characteristics of rows of short wave fin and interrupted distance between discontinuous short wave fins were revealed numerically. The results indicated that,compared with the original continuous wave fin,the discontinuous short wave fin effectively improved the air-side heat transfer of flat tube under the air flow velocities in the practical application of engineering. Moreover,the increment of pressure loss of air-side flow was restricted for the discontinuous short wave fins because of the reduction of contact areas between the air flow and fin surface.

Extending the VDPC+BCS formalism by including three-body forces

Recently,Jia proposed a formalism to apply the variational principle to a coherent-pair condensate for a two-body Hamiltonian.The present study extends this formalism by including three-body forces.The result is the same as the so-called variation after particle-number projection in the BCS case,but now,the particle number is always conserved,and the time-consuming projection is avoided.Specifically,analytical formulas of the average energy are derived along with its gradient for a three-body Hamiltonian in terms of the coherent-pair structure.Gradient vanishment is required to obtain analytical expressions for the pair structure at the energy minimum.The new algorithm iterates on these pair-structure expressions to minimize energy for a three-body Hamiltonian.The new code is numerically demonstrated when applied to realistic two-body forces and random three-body forces in large model spaces.The average energy can be minimized to practically any arbitrary precision.