复叠机组低温机排气冷却器的必要性及计算

复叠机组低温机排气温度较高．容易引起各种损害,特别是造成分油不良,油在蒸发器存入过多,影响换热,从而使蒸发温度降低,使回油更加困难,且较低的蒸发温度会造成更大的排气过热,如此形成恶性循环。因此在低温机排气加装排气冷却器,及冷却器的正确选择计算是重要的。本文就此项问题提出一种冷却器结构及计算方法。

微型高压压缩机热力复算模型改进

针对微型高压压缩机级间冷却随工作条件变化难以准确确定,对传统热力复算模型进行改进,将级间传热过程与热力复算过程进行耦合,得到一种适应于微型高压压缩机的新热力复算模型,并利用新模型对某一微型压缩机进行了热力复算,验证了新模型的准确性。

NUMERICAL SIMULATION STUDY ON WUQING GEOTHERMAL RESERVOIR,TIANJIN

In this paper the computer code of AUTOUGH2 is used to carry out numerical simulation study on the Wuqing geothermal reservoir for evaluating reservoir performance upon different exploitation schemes.The simulating calculation and analysis of two main cases,production without reinjection and production with reinjection,were carried out to illuminate and compare the temperature and pressure profiles with distance and time.The water level or pressure will decrease with the time of production,and the reinjection will cause the cooling effect of reinjection on the production zone.

促进中密度纤维板发展的新工艺

近年来干法生产纤维板的技术进步是举世目睹的。多年来,连续压机技术,除了用于生产中密度纤维板外,也被广泛地用于轻质(LDF)或高密度(HDF)纤维板的生产中。通过改变压机入口形状,以及对整个压制长度压制压力的精密控制,大大加宽了纤维板的密度变化范围。

Aqueous ammonia solution cooling absorption refrigeration driven by fishing boat diesel exhaust heat

A solution cooling absorption（SCA）approach is proposed to modify the aqueous ammonia absorption refrigerat-ion cycle using the strong solution from the absorber to cool the forepart of the absorption in the cycle for reclaiming some portion of absorption heat.As a consequence of raised temperature at the inlet,the strong solution partially boils at the outlet of the solution heat exchanger,and diminishes the thermal heat consumption of the heat source.The calculation results show that the coefficient of performance（COP）of this modified cycle is about 28.3% higher than that of the traditional cycle under typical conditions;while the required heat transfer area of the total heat exchangers of the cycle is somewhat less than that of the traditional one.The capacity of refrigeration with the new absorption cycle is more than doubled in contrast to the adsorption scheme with an identical configuration.It is sufficient to supply a fishing boat the chilling capacity for preservation of fishing products with the modified cycle chiller driven by its diesel engine exhaust.

Effect of aging treatment on evolution of S'phase in rapid cold punched Al−Cu−Mg alloy

High-resolution transmission electron microscopy(TEM),X-ray diffractometer(XRD),and hardness test were used to study the evolution of long plate-shaped S'phase in the spray-formed fine-grained Al−Cu−Mg alloy during aging after rapid cold punching deformation.Results show that the long plate-shaped S'phase in the extruded Al−Cu−Mg alloy undergoes evident distortion,brittle failure,separation and redissolution,during rapid cold punching deformation,leading to the transformation of long plate-shaped S'phase into short rod or even redissolution and disappearance,causing the matrix to become a supersaturated solid solution.After the aging treatment,the reprecipitation of the phases occurs,and these aging phases are mainly long plate-shaped and granular.The incompletely dissolved S'phase acts as nucleation core,promoting uphill diffusion of the surrounding solute atoms.The S'phase gradually grows with increasing the aging time.The completely dissolved S'phase forms the incoherent equilibrium phase with the matrix to reduce its free energy.After rapid cold punching,the aging response of the deformed Al−Cu−Mg alloy is accelerated,and the hardness of the alloy is substantially increased.

A Novel Process for Natural Gas Liquids Recovery from Oil Field Associated Gas with Liquefied Natural Gas Cryogenic Energy Utilization

A novel process to recovery natural gas liquids from oil field associated gas with liquefied natural gas (LNG)cryogenic energy utilization is proposed.Compared to the current electric refrigeration process,the proposed process uses the cryogenic energy of LNG and saves 62.6%of electricity.The proposed process recovers ethane, liquid petroleum gas(propane and butane)and heavier hydrocarbons,with total recovery rate of natural gas liquids up to 96.8%.In this paper,exergy analysis and the energy utilization diagram method(EUD)are used to assess the new process and identify the key operation units with large exergy loss.The results show that exergy efficiency of the new process is 44.3%.Compared to the electric refrigeration process,exergy efficiency of the new process is improved by 16%.The proposed process has been applied and implemented in a conceptual design scheme of the cryogenic energy utilization for a 300 million tons/yr LNG receiving terminal in a northern Chinese harbor.

Integration of Low-level Waste Heat Recovery and Liquefied Nature Gas Cold Energy Utilization

Two novel thermal cycles based on Brayton cycle and Rankine cycle are proposed, respectively, which integrate the recovery of low-level waste heat and Liquefied Nature Gas （LNG） cold energy utilization for power generation. Cascade utilization of energy is realized in the two thermal cycles, where low-level waste heat,low-temperature exergy and pressure exergy of LNG are utilized efficiently through the system synthesis. The simulations are carried out using the commercial Aspen Plus 10.2, and the results are analyzed. Compared with the conventional Brayton cycle and Rankine cycle, the two novel cycles bring 60.94% and 60% in exergy efficiency, respectively and 53.08% and 52.31% in thermal efficiency, respectively.

An analytical model for predicting sheet springback after V-bending

Springback is caused by the redistribution of stress in sheet material after the tooling is removed. Precise prediction of sheet springback is very important in die design. Based on Hill’s yielding criterion and plane strain condition, an analytical model is proposed in this paper which takes into account the effects of contact pressure, the length of bending arm between the punch and die, transverse stress, neutral surface shifting and sheet thickness thinning on the sheet springback of V-bending. The predicted results by this analytical model indicated that the contact pressure and transverse stress have much effect on the springback when the bending ratio (the ratio of punch radius to sheet thickness) is less than five. The contact pressure declined when the length of bending arm goes up, which means that shorter length of bending arm will result in larger springback. The effect of neutral surface shifting on the springback is less than that of contact pressure and decreases with the bending ratio. However, this research showed that the influence of thickness thinning on the springback can be ignored. Comparison with finite element method (FEM) simu-lating results shows that the predicted results by the analytical model accord well with simulation results by FEM. In addition to that, the bending ability—the limit bending ratio for a given sheet thickness and material properties was also determined.

Re-dissolution and re-precipitation behavior of nano-precipitated phase in Al-Cu-Mg alloy subjected to rapid cold stamping

High-resolution transmission electron microscopy(TEM),X-ray diffractometry(XRD),energy dispersive spectroscopy(EDS)and hardness test were used to study the re-dissolution and re-precipitation behavior of nano-precipitates of the spray-formed fine-grained Al-Cu-Mg alloy during rapid cold stamping deformation.Results show that the extruded Al-Cu-Mg alloy undergoes obvious re-dissolution and re-precipitation during the rapid cold-stamping deformation process.The plasticθ′phase has a slower re-dissolution rate than the brittle S′phase.The long strip-shaped S′phases and the acicularθ′phases in Al-Cu-Mg alloy after three passes of cold stamping basically re-dissolved to form a supersaturated solid solution.A large number of fine granular balanceθphases precipitate after four passes of rapid cold-stamping deformation.Rapid cold stamping deformation causes the S′phase andθ′phase to break and promote the nano-precipitate phases to re-dissolve.The high distortion free energy of the matrix promotes the precipitation of the equilibriumθphase,and the hardness of the alloy obviously increases from HB 55 to HB 125 after the rapid cold stamping process.

1.3μm high-power superluminescent diode

The result of the evaporation of Sio/SiO2 two layer antireflection coatings monitored by the MODEL IL 400 DEPOSITION CONTROLLER is reported.A superluminescent diode with high output power is fabricated by evaporating antireflection coating on the front facet of 1.3μm buried heterostructure laser.

An approach for IC engine coolant energy recovery based on low-temperature organic Rankine cycle

To promote the fuel utilization efficiency of IC engine, an approach was proposed for IC engine coolant energy recovery based on low-temperature organic Rankine cycle(ORC). The ORC system uses IC engine coolant as heat source, and it is coupled to the IC engine cooling system. After various kinds of organic working media were compared, R124 was selected as the ORC working medium. According to IC engine operating conditions and coolant energy characteristics, the major parameters of ORC system were preliminary designed. Then, the effects of various parameters on cycle performance and recovery potential of coolant energy were analyzed via cycle process calculation. The results indicate that cycle efficiency is mainly influenced by the working pressure of ORC, while the maximum working pressure is limited by IC engine coolant temperature. At the same working pressure, cycle efficiency is hardly affected by both the mass flow rate and temperature of working medium. When the bottom cycle working pressure arrives at the maximum allowable value of 1.6 MPa, the fuel utilization efficiency of IC engine could be improved by 12.1%.All these demonstrate that this low-temperature ORC is a useful energy-saving technology for IC engine.

The Size Effects on Process Design of Micro Deep Drawing

This paper suggested to reformulate cylindrical deep drawing parameters with dimensionless form. A diagram, in which a feasible zone is drawn to bound both the maximal allowable tension and compression stress during the deep drawing process, was established. Since it is presented in a dimensionless form, it may be applied for both conventional and micro deep drawing. Cylindrical cup deep drawing was taken as an example to show the dimensionless process design method. In addition, the size effects should be taken into account. Two kinds of size effects on micro deep drawing were investigated, which can be explained by surface layer model and strain gradient model. Numerical simulations were carried out to compare the strain distribution with or without consideration of size effect.

A Two-step Design Method for Shaft Work Targeting on Low-temperature Process

In low-temperature processes, there are interactions between heat exchanger network(HEN) and refrigeration system. The modification on HEN of the chilling train for increasing energy recovery does not always coordinate with the minimum shaft work consumption of the corresponding refrigeration system. In this paper, a systematic approach for optimizing low-temperature system is presented through mathematical method and exergy analysis. The possibility of "pockets", which appears as right nose section in the grand composite curve(EGCC) of the process, is first optimized. The EGCC with the pockets cutting down is designed as a separate part. A case study is used to illustrate the application of the approach for a HEN of a chilling train with propylene and ethylene refrigerant system in an ethylene production process.

Evolution of microstructure, phase composition, and tensile properties of severely cold deformed titanium metastable β alloy in rapid continuous heating

Influence of severe cold deformation of titanium alloy Ti-1.5%A1-6.8%Mo-4.5%Fe in metastable β condition on the evolution of phase composition, microstructure, and tensile properties during continuous rapid heating was studied. As-deformed alloy was characterized by quasi-amorphous single-phase β condition with an abnormal temperature dependence of electric resistance that was normalized after 48 h exposure at room temperature as a result of isothermal ω phase precipitation. Subsequent rapid heating with a rate of 5 ℃/s caused recovery and recrystallization. Tensile properties of the alloy after different treatments were determined and discussed.

Evaluations of the Sensory Quality Indices and Freshness Assessment of Nile Tilapia Oreochromis niloticus Fillets Fed Recycled Food Waste Materials

This study was designed to evaluate the sensory quality indices, freshness assessment and safety of eating Nile tilapia fed recycled food waste materials [food industry waste （FIW） and soy sauce waste （SSW）] for 32 weeks using K values, IMP content and microbial viable cell count. Five experimental diets were formulated at 0% and 20%-22% inclusion level of recycled food wastes. The diets were designated as D 1： 0% of recycled food waste, D2： 20% inclusion of FIW, D3： 20% inclusion of FIW and SSW, D4： 20% inclusion of FIW and tryptophan, and D5： 22% inclusion of SSW. The result from the body composition shows that D I had higher carcass protein, while D3 had the highest lipid content and there was no significant difference in the carcass moisture and ash contents among all treatments. The results of microbial viable cell counts showed that no significant differences were observed among the dietary treatments and all the fish fed experimental diets still remained fresh four days after refrigerated storage at 5 ~C. In addition, no significant differences were noted among the K value concentrations of all the fish fed the experimental diets. From the result of this study, we concluded that using 20% inclusion of recycled food waste materials （FIW and SSW） in the diet of tilapia had no negative effect on the flesh of the fish; hence, recycled food waste could be a good alternative ingredient to aquaculture.

Quantitative evaluation of urban park cool island factors in mountain city

Evaluating how park characteristics affect the formation of a park cool island(PCI) is the premise of guiding green parks planning in mountain cities.The diurnal variation of PCI intensity was achieved,and correlations between PCI intensity and park characteristics such as park area,landscape shape index(LSI),green ratio and altitude were analyzed,using 3 010 temperature and humidity data from measurements in six parks with typical park characteristics in Chongqing,China.The results indicate that:1) the main factor determining PCI intensity is park area,which leads to obvious cool island effect when it exceeds 14 hm2;2) there is a negative correlation between PCI intensity and LSI,showing that the rounder the park shape is,the better the cool island effect could be achieved;3) regression analysis of humidity and PCI intensity proves that photosynthesis midday depression(PMD) is an important factor causing the low PCI intensity at 13:00;4) the multivariable linear regression model proposed here could effectively well predict the daily PCI intensity in mountain cities.

Exploring heating performance of gas engine heat pump with heat recovery

In order to evaluate the heating performance of gas engine heat pump（GEHP） for air-conditioning and hot water supply, a test facility was developed and experiments were performed over a wide range of engine speed（1400-2600 r/min）, ambient air temperature（2.4-17.8 ℃） and condenser water inlet temperature（30-50℃）. The results show that as engine speed increases from 1400 r/min to 2600 r/min, the total heating capacity and energy consumption increase by about 30% and 89%, respectively; while the heat pump coefficient of performance（COP） and system primary energy ratio（PER） decrease by 44% and 31%, respectively. With the increase of ambient air temperature from 2.4 ℃ to 17.8 ℃, the heat pump COP and system PER increase by 32% and 19%, respectively. Moreover, the heat pump COP and system PER decrease by 27% and 15%, respectively, when the condenser water inlet temperature changes from 30 ℃ to 50 ℃. So, it is obvious that the effect of engine speed on the performance is more significant than the effects of ambient air temperature and condenser water inlet temperature.

Resource Evaluation of Heavy Rare Earth Derived from the Spent Gd203 Burnable Poison in LWRs

A burnup calculation has been performed to evaluate heavy rare earth （terbium--Tb, dysprosium--Dy） production in spent gadolinium oxide （Gd203） installed as a BP （burnable poison）. Each amount of Tb and Dy production derived from the BP has been about 30-40 times larger than those created in FP （fission products）. Required cooling time to achieve exemption level on radioactivity concentration produced Tb and Dy derived from the BP are much shorter （BP-Tb： 7.9y, BP-Dy： 〈 0.1y） than those created in FP （FP-Tb： 3,616y, FP-Dy： 6.9y）. However, the BP is mixed homogeneously with UO2 pellet in current nuclear fuel system of LWRs （light water reactors）, and hence mixing of FP cannot be not avoided. In such a mixture case, the required cooling time of recovered Tb will become 2,653y and that of recovered Dy be 4.8y. For this reason, recovered Tb is unlikely to be resource for utilization, while recovered Dy must be the resource provided the precise separation from the other FP.