Freezing processes in high-pressure domains

Experimental freezing of water in high-pressure domain is studied considering temperature reduction (TRF) as well as high-pressure-assisted freezing (HPAF). The most important advantage of HPAF is that the whole volume of the sample is subcooled when an expansion is made, so a rapid and uniform nucleation and growth of ice crystals are produced. In this work through mathematical modelling the amount of ice appearing instantaneously in the latter freezing, is predicted.     

对羟基苯乙酮的合成研究

以苯甲醚、乙酰氯为原料,AlCl3为催化剂通过Friedel-Crafts酰基化反应和脱甲基化两步反应得到对羟基苯乙酮。考查了反应时间、反应温度等条件对反应的影响,确定了反应的最佳条件。在最佳工艺条件下对羟基苯乙酮的总收率为65%,经熔点和红外光谱表征与目标化合物的结构一致。     

利用气顶能量合理开发扎纳若尔油藏的可行性

哈萨克斯坦扎纳若尔气顶油藏采用在油气界面附近屏障注水，封隔油气区，先开发油环（油环采用面积注水），后期开发气顶或在水障形成后油气同采的方式进行开发。以该油田Б南油藏为例，在深入分析屏障注水量变化与气顶膨胀增油作用关系的基础上，探讨了以屏障注水结合油环内面积注水方式开发的气顶油藏，适时降低屏障注水量，充分利用气顶膨胀能量，实现高效益开发的可行性。应用数值模拟方法进一步确定了气顶油藏合理的年注采比以及屏障注水井和油环内面积注水井注水量的比例关系。     

脱除煤沥青中3,4-苯并芘及其机理研究

以聚乙二醇和三聚甲醛为复合改性剂,采用聚合物改性法脱除煤沥青中致癌多环芳烃3,4-苯并芘,在复合改性剂比例(聚乙二醇与三聚甲醛的比)为4∶6时脱除率可达76.0%。元素分析结果表明,改性煤沥青的C、S元素含量降低,H元素含量升高,C/H值和芳香度(fa)降低,说明改性煤沥青的软化点降低、体系的稳定性下降。红外光谱分析结果表明,聚乙二醇与3,4-苯并芘的反应属于O-烷基化反应,三聚甲醛与3,4-苯并芘的反应属于C-烷基化反应。     

A household dishwasher heated by a heat pump system using an energy storage unit with water as the heat source

Electricity usage by a household dishwasher can be reduced by using a heat pump system to heat the dishwasher cabinet, dishware and washing water. The evaporator obtains the energy from an energy storage unit which consists of a container filled with water which freezes to ice. The majority of the heat transfer from the energy storage to the evaporator occurs when ice is created in the energy storage unit. A transient simulation model of a dishwasher with a heat pump system was developed and compared to an experimental setup with good agreement. A simulation study of the compressor cylinder volume and the compressor operating time was performed. The results showed a 24% reduction in total electricity use compared to a dishwasher cycle using a traditional electric element.     

Pool boiling of ammonia/water and its pure components: Comparison of experimental data in the literature with the predictions of standard correlations

Although ammonia/water has been used for decades as a working pair in absorption cycles for industrial refrigeration, very limited data are available on boiling heat transfer of this mixture. The intention of this work is to carry out a bibliographic revision of the information available in the open literature about nucleate pool boiling of the ammonia/water mixture and its pure components. The experimental data have been compared with existing prediction correlations for the pure components and also for their mixtures.For water, all the pure component pool boiling correlations gave similar predictions and were in good agreement with experimental data. For ammonia the prediction of the correlation and the experimental data showed more differences.At a given heat flux, the experimental data show that the mixture pool boiling heat transfer coefficient is lower than that obtained with pure components. Three of the well-known correlations for mixtures were compared against the experimental data. None of these correlations provided a good prediction of the mixture pool boiling heat transfer coefficient over a wide range of mass fraction. Furthermore, a new correlation has been proposed.     

Friction factor correlation and pressure loss of single-phase flow inside herringbone microfin tubes

Pressure drop of single-phase turbulent flow inside herringbone microfin tubes of different fin dimensions has been measured experimentally to develop a general correlation of single-phase friction factor for the herringbone tubes. Water has been used as a working fluid and the mass flow rate has been varied from 0.03 to 0.2 kg/s, where the Reynolds number range is 10⁴ to 6.5 × 10⁴. Comparison of experimental data of the herringbone microfin tubes with those of helical microfin and smooth tubes shows that pressure drop of the herringbone tube is significantly higher than the helical and smooth tubes depending on the fin geometric parameters and mass velocity of the working fluid. Through semi-analytical approach and using the present experimental data, a new correlation of single-phase friction factor for the herringbone microfin tubes has been proposed incorporating the effects of fin geometric parameters. The proposed correlation can predict the experimental data within ±10%.     

Assessment of boiling heat transfer correlations in the modelling of fin and tube heat exchangers

A new way to assess the performance of refrigeration system models is presented in this paper, based on the estimation of cycle parameters, such as the evaporation temperature which will determine the validity of the method. This paper is the first of a series which will also study the influence of the heat transfer coefficient models on the estimation of the refrigeration cycle parameters. It focuses on fin and tube evaporators and includes the dehumidification process of humid air. The flow through the heat exchanger is considered to be steady and the refrigerant flow inside the tubes is considered one-dimensional. The evaporator model is discretised in cells where 1D mass, momentum and energy conservation equations are solved by using an iterative procedure called SEWTLE. This procedure is based on decoupling the calculation of the fluid flows from each other assuming that the tube temperature field is known at each fluid iteration. Special attention is paid to the correlations utilised for the evaluation of heat transfer coefficients as well as the friction factor on the air and on the refrigerant side. A comparison between calculated values and measured results is made on the basis of the evaporation temperature. The experimental results used in this work correspond to an air-to-water heat pump and have been obtained by using R-22 and R-290 as refrigerants.     

Assessment of boiling and condensation heat transfer correlations in the modelling of plate heat exchangers

This paper studies refrigeration cycles in which plate heat exchangers are used as either evaporators or condensers. The performance of the cycle is studied by means of a method introduced in previous papers which consists of assessing the goodness of a calculation method by looking at representative variables such as the evaporation or the condensation temperature depending on the case evaluated. This procedure is also used to compare several heat transfer coefficients in the refrigerant side. As in previous works the models of all the cycle components are considered together with the heat exchanger models in such a way that the system of equations they provide is solved by means of a Newton–Raphson algorithm. Calculated and measured values of the evaporation and the condensation temperatures are also compared. The experimental results correspond to the same air-to-water heat pump studied in other papers and they have been obtained by using refrigerants R-22 and R-290.     

氰化工艺过程中金属存量计算方法探讨

为搞好金属平衡，减少理论与实际差值，依据某黄金矿山氰化工艺流程特点，对脱药用单层浓密切、漫出槽、三层洗涤浓密机三个作业中的金属存量的计算方法进行了探讨。