BOILNG HEAT TRANSFER ON SURFACES WITH ARTIFICIAL NUCLEATION SITES (Ⅱ) MECHANISM OF NUCLEATE BOILING AND EFFECT OF CAVITY SIZE, CAVITY DENSITY ON BOILING HEAT TRANSFER

A new comprehensive physical model for nucleate boiling heat transfer on surfaces with artificial nucleation sites has been proposed. Good agreement with experimental results has shown the applicability of the model.     

TWO-PHASE FLOW AND HEAT TRANSFER IN VERTICAL U-SHAPED TUBES(Ⅱ)DETERIORATION OF BOILING HEAT TRANSFER IN WASTE HEAT BOILERS

f .Introduction The two一Phase flow and boiling heat tra一lsfer eharaeteristics in the bends ofU一shaPedtubes are eomPlieated beeause of the combined effeets of gravitational and eentrifugal Ibrees之连5 well as other factorsl sueh as seeondary flow ete.Ho     

TWO-PHASE FLOW AND HEAT TRANSFER IN VERTICAL U-SHAPED TUBES(Ⅲ)ELIMINATING BOILING HEAT TRANSFER DETERIORATION BY MEANS OF INSERTED TURBULATORS

1 .Introduetion Aeeident of tube failure in the waste heat boilers with vertiealU一shaPed tubes used insynthetie ammonia Plants oecurs frequently in oPeration.In order to find out the cause ofthe tube failure,and to Present the method of solution,investig…     

THE EFFECT OF FREE STREAM CONCENTRATION ON HEAT AND BINARY MASS TRANSFER WITH THERMODYNAMIC COUPLING IN CONVECTION ON A ROTATING DISC†

Simultaneous heat and mass transfer, which arises from injecting a gas (helium or hydrogen) from or through the solid surface into a flowing external stream, has been studied for a rotating disc geometry. The effects of concentration levels of the injected gas in the external stream on the thermodynamic coupling in the presence of centrifugal force have been investigated over a wide range of T_w/T_e.

Boundary layer equations for heat and mass transfer were solved numerically. Exact and linearized approximate solutions were obtained. The results have shown that the thermal diffusion effect on mass transfer becomes increasingly important as the free stream concentration increases and as T_w/T_e departs from unity. The diffusion thermo effect on heat transfer was found to be the most important when the free stream concentration is zero and as T_w/T_e approaches unity.     

SYNTHESIS OF FLEXIBLE HEAT EXCHANGER NETWORKS WITH STREAM NO - SPLITTING(Ⅰ) BASED ON RANGES OF STREAM SUPPLY TEMPERATURES

提出了基于温度波动的无分流换热网络的超结构模型和同步优化的弹性设计方法。对于起始温度在一定范围内波动的物流进行预处理即分段处理,并提出了分段原则;提出了基于规则的网络超结构模型并建立了弹性换热网络同步优化的数学模型;采用遗传算法求解了所提出的优化数学模型;提出了分段物流的合并及能量松弛的原则,对分段物流进行合并,并通过能量松弛方法得到优化的弹性换热网络结构。通过几个换热网络的弹性设计,说明了本方法的有效性和应用前景。     

ENHANCEMENT OF FINE ADSORBENT PARTICLES ON GAS - LIQUID MASS TRANSFER (Ⅰ)MECHANISM

对于两元物系,进行了吸附剂细粉（小于10μm）强化气液两相传质的机理研究。分析了吸附对气液两相传质的强化作用,以及细粉颗粒对流体性质和组分扩散的影响,提出了吸附剂细粉强化传质的机理。根据渗透理论和对吸附等温线的线性化处理,推导出了相应的数学模型,并进行了模拟计算。     

TWO-PHASE FLOW AND HEAT TRANSFER IN VERTICAL U-SHAPED TUBES(Ⅰ)FLOW PATTERN TRANSITIONS IN THE BEND

1 .Introduetion The vertiealU一shaPed boiling tubes are widely usedi一飞waste heat boilers,nuelear reaetorsteam generators,evaPorators and heat exehangers.Fo一instanee,waste heat boilers withU一shaPed tube are used in synthetie ammonia fertilizer Plants w     

A NEW METHOD FOR ACHIEVING DROPWISE CONDENSATION (Ⅲ) DETERMINATION OF DROPWISE CONDENSATION HEAT TRANSFER COEFFICIENT AND LIFETIME TEST OF THE NEW SURFACE

Heat transfer characteristics of the new surfaces were determined through temperature measurements, and the results were compared with dropwise condensation (DWC) studies from various sources.Duration tests for DWC were carried out on two different surfaces, giving a duration of perfect DWC over 15000 hours.     

SIMPLIFIED FRAMEWORK FOR DESCRIPTION OF MIXING WITH CHEMICAL REACTIONS (Ⅰ) PHYSICAL PICTURE OF MICRO- AND MACROMIXING

1 INTRODUCTION When a fluid is injected into a turbulence field to mix with another fluid,twohomogenization processes take place simultaneously:micromixing(on the molecularscale)and macromixing(on the mixer scale).For micromixing,three successive stages arerecognized at high Schmidt number(1)turbulent dispersion,in which the original ma-terial lumps are dispersed by turbulence into discrete elements with smallest eddy sizeλ_k;(2)viscous deformation,in which the size of the elements is further reduced     

DESENSITIZING EFFECT OF ISOMERIC METALLORGANIC PALLADIUM (II) COMPOUNDS WITH THIOSEMICA-RBAZIDE ON THE DEVELOPMENT PROCESS OF SILVER HALIDE PHOTOGRAPHIC MATERIALS

Some chemical compounds can be used in the chemical photographic development process of silver halide panchromatic motion picture materials to decrease their sensitivity upon exposure whereby their development is possible at relatively bright illumination. Such compounds can be the organic compounds of o-elements with complanar structure. It was observed, in particular, the pronounced desensitizing effect of bis (thiosemicarbazido) palladium (Ⅱ) dichloride of the formula:     

EXTRACTION OF NEPTUNIUM AND PLUTONIUM NITRATES WITH n-OCTYL(PHENYL)-N,N-DIISOBUTYL-CARBAMOYLMETHYLPHOSPHINE OXIDE∗

Distribution equilibria of Np and Pu in various valence states and stripping of Np(V) were studied in a system involving 0.20 M n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide + 1.2 M tributyl phosphate in dodecane as a solvent. Np(V) is weakly extractable at <2 M nitric acid but more effectively extractable at >3 M nitric acid, due to the disproportionation of Np(V) to Np(IV) and Np(VI). Addition of nitrous acid to solutions containing Np(V) increases the over-all extractabllity of Np, due to its partial oxidation to Np(VI). This is also the case In the presence of oxalic acid, both at room temperature and at 40^°C. Both Np(IV) and Np(VI) are highly extractable, but the reduction of Np(V,VI) to Np(IV) is slow even with a reductant as strong as sodium formaldehyde sulfoxylate. Pu(IV) is highly extractable and its reduction to Pu(III) with sulfoxylate Is incomplete in the two-phase system if the aqueous phase contains >0.5 M nitric acid. Extracted Np(VI) can be stripped by reduction to Np(V). The stripping rate is, however, slow with nitrous acid as the reductant at low nitric acid concentration. The reduction of Np(VI) by hydrogen peroxide is fast, but is followed by further reduction to Np(IV). Sulfurous acid reduces Np(VI) rapidly and, if no iron is present, only to Np(V), but Fe(II) induces further reduction to Np(IV).     

THE MASS TRANSFER BEHAVIORS OF FE(Ⅲ), CO(Ⅱ) AND NI(Ⅱ) IN SULFURIC ACID WITH CYANEX302 BY USINGMICROPOROUS HOLLOW FIBER

In this paper the mass transfer behaviors of Fe(Ⅲ), Co(Ⅱ) and Ni(Ⅱ) with Cyanex302(bis(2,4,4- trimethylpentyl)monothiophosphinic acid) from sulfate medium by using hollow fiber membrane in counter-currently circulating operation were studied. The effect of acidity in aqueous solution and the extractant concentration on the mass transfer coefficient (Kw) was discussed. The reaction mechanism of membrane extraction was considered as a false one series reaCtion and the rate controlling step was membrane resistance. When the value of Kw arrived at 1.0 × 10-6 m/s, △pH:CoFe equaled tO 6.225, and △pH:NiFe was bigger than △p HCoFe.     

NUMERICAL MODELING OF COUPLED MOMENTUM,HEAT AND MASS TRANSPORT IN FALLING FILM CRYSTALLIZATION PROCESS (Ⅱ)SIMULATION

采用液固二相分区域统一模型 ,以二元有机熔体 (萘 -硫茚 )为例 ,对实验管式降膜结晶器的动量、热量和质量传递过程进行了数值模拟 ,获得了液相区和固相区随时间的变化和枝晶状液固两相区内固相含量的变化及全场温度分布以及主组分萘分布及流场速度分布随时间的变化 .由积分得到的结晶层厚度及萘纯度与相应的实验数据进行了比较 ,所得结果在未引入任何经验常数的条件下与实验结果符合较好 .所建立的液固二相分区域统一模型可以较好地处理实际降膜结晶过程中枝晶状固液两相共存区晶体生长现象及不规则液固相变界面     

STUDIES ON THE RELATIONSHIP BETWEEN THE NETWORK STRUCTURE AND THE MECHANICAL PROPERTIES OF RUBBER VULCANIZATES (Ⅰ) THEORY OF ELASTICITY FOR RUBBER VULCANIZATES WITH CARBON BLACK FILLERS IN LARGE DEFORMATION

A model structure formed by the combination of crosslinked, trapped entanglement and carbon black-polymer chain networks has been developed for rubber vulcanizates with carbon black fillers. Based on thisstructure and the proposed mechanism of large deformation, the elastic free energy     

EFFECT OF CHAIN LENGTH OF ALKANE-1-HYDROXY-1, 1′-METHYLDIPHOSPHONIC ACIDS ON THE IRON (III) LIQUID–LIQUID EXTRACTION

ABSTRACT

(1-Hydroxy-1-phosphonohexadecyl) phosphonic acid (HPHPA) and (1-hydroxy-1-phosphonododecyl) phosphonic acid (HPDPA) were prepared by reaction of phosphorus trichloride with palmitic and lauric acids, respectively. After purification, these products were characterized by elemental microanalysis and by IR, ¹H, ³¹P?NMR spectroscopies. In this paper, we propose a tentative assignment for the shifts of those two ligands and their specific complexes with iron (III). A spectroscopic analysis has showed that coordination of iron (III) takes place via oxygen atoms. We also measured the extraction of Fe⁺³ by HPHPA and HPDPA from [CCl₄-Octanol (v/v: 90%/10%)] solutions. The complexes formed in the organic phase may be Fe[C₁₁ H₂₃C(OH)(PO₃H)₂]Cl, 3H₂O with HPDPA and Fe[C₁₅H₃₁C(OH) (PO₃H)₂]Cl, 3H₂O with HPHPA, respectively. HPHPA as ligand exhibits a stronger extracting power for Fe³⁺ and has a more hydrophobic character than HPDPA.     

EFFECT OF NUCLEOTIDE SEQUENCE ON THE BINDING OF (–)–ANTI–DIBENZO– [a,l]PYRENE–11,12–DIOL 13,14–EPOXIDE TO SHORT OLIGODEOXYRIBONUCLEOTIDES

Abstract

Seven selfcomplementary decamer oligodeoxyribonucleotides were reacted with (–)–anti–(11R,12S)–dihydrodiol (13S,14R)–epoxide of dibenzo[a,l]pyrene (DB[a,l]PDE). The oligodeoxyribonucleotides were postlabeled with ³³P–ATP, digested to mononucleotides and the amount of adducts formed was determined by HPLC. We found that the nucleotide sequence affects the binding of DB[a,l]PDE to DNA. DB[a,l]PDE binds better to GC rich oligodeoxyribonucleotides than to AT rich oligodeoxyribonucleotides. The CGC sequence binds more DB[a,l]PDE than GGC, TGC, GAT or AGC sequences. The reactions were carried out on ice or at 37°C. There was no evidence of temperature effects on the amount of DB[a,l]PDE binding.