流动与非流动测热方式对酶催化反应放热测量的影响

采用微量热仪(Micro DSCⅢ)对鸡肝酯酶催化α-乙酸萘酯水解反应进行了流动与非流动测热方式的对比研究。研究显示,流动测热的流速对反应热测量结果有较大影响,当30μL浓度为120mmol/L的α-乙酸萘酯底物以0.22 mL/min的流速流经0.5 g固定化鸡肝酯酶时,催化反应放出的热量为0.033 J,持续放热时间为495 s;而流速为0.18 mL/min与0.35 mL/min时,测得的放热量分别为0.030 J与0.025 J,持续放热时间分别为625 s与365 s。用与流动测热相同酶活单位的鸡肝酯酶液酶进行非流动测热,所得到目的反应热的量为0.035 J,持续放热时间为800 s。与非流动方式测热相比,流动测热方式的测量灵敏度较高,检测出目的放热量所需时间较短,但不能充分检测出生化反应热总热量。     

量热法研究缓蚀作用

<正> 前言研究金属在酸中的腐蚀及缓蚀作用多采用失重法,量气法,电化学法,比色分析法等,失重法为经典方法,但操作较繁。其它方法虽各有一些优点,但均费时,仪器要求也较高。近年来,国外采用Mylius的量热法研究缓蚀剂的缓蚀作用,此法所用仪器简     

绝热量热法测量高分子凝聚液比热容

利用精密自动绝热比热容实验装置，测量了丁苯橡胶合成过程中高分子凝聚液的比热容数据，为大型丁苯橡胶合成装置建造提供了基础物性数据。     

差示扫描量热法及其在商品检验中的应用

差示扫描量热法（DSC）是一种较新型有效的热分析技术,由于技术上的进步和计算机的广泛使用,使得该技术得到了广泛的应用。扼要介绍了DSC的测试原理及其在进出口商品检验中的应用,并对其存在的问题进行了探讨。     

差示扫描量热法对PET热性能的研究

本文通过差示扫描量热仪及其他分析仪器相结合,分析了两个不同厂家的PET原料,通过改变DSC的实验条件确定了两种不同厂家PET原料的差别,样品B的结晶度较瓶用料样品的结晶度高,比瓶用料样品的耐热性强。文章分析了这种差别,指出这种差别不仅与样品的热历史有关,并且与其加工工艺及配料有关。通过多种仪器的联合测试,为厂家提供了以下信息：性能上的差异不是因为催化剂引起的,而是后期加工时的条件不同造成的。     

鹿耳促菌作用的量热法研究

用热活性检测仪测定了茸对大肠杆菌,金黄色葡萄球菌起促进代谢作用的热功率－时间曲线,并根据曲线建立了细菌促进生长的实验模型,计算了生长速率常数和最佳促菌浓度。     

聚酯的差示扫描量热法热性能分析

使用DSC差示扫描量热仪分析了三种聚酯产品的热性能。同等试样量时,从测得试样的熔点、结晶度及曲线图形可以分析判断出,PET-2聚酯样品产品质量最好。     

相关分析及量热法在油水两相流测量中的应用

用相关分析及量热法相结合用于油水两相流测量,并进行了相应的理论分析和试验研究。利用上下游温升的相关性测量总流流量,再用量热法来测量油水比,从而得到油水两相的各自流量。同时,在以前研究的基础上对实验段进行了必要的改进。结果表明,这有利于提高测量精度     

立方型状态方程用于蒸发热的计算

推导出立方型状态方程计算纯流体蒸发热的新公式,该计算式的特点是式中含有能量参数对温度的导数 da/dT,而与 a(T)无关。根据这一公式对立方型状态方程推算蒸发热进行了比较分析,提出a(T)与 da/dT 相互独立的计算方法,并用 Peng-Robinson 方程对70多种物质(包括烃、醇、卤代烃、酮、无机气体等)进行了关联计算,蒸汽压和蒸发热的平均相对误差分别为0.70%和1.33%。     

AN APPARATUS FOR MEASURING THERMAL CONDUCTIVITY OF LIQUIDS UNDER HIGH PRESSURE

We have reported a method for measuring the thermal conductivity of liguids un-der high pressure previously [1,2].Such data are necessary for improving thetechnologies such like processing as acidity,pressure cracking,thermal exploitation ofpetroleum,etc. An apparatus has thus been constructed,as shown schematically in Fig.1,tomeasure the thermal conductivity of liquids under pressure up to 25 MPa and temperatureranging from 150 to 250℃.The thermal conductivity cell is cylindrical in from,35mmin length and 25mm in inner diameter.The sample is poured into the cell through the     

GENERALIZED METHOD FOR CALCULATING LATENT HEAT OF VAPORIZATION

The latent heat of vaporization of a pure substance is often required in many engineering design/process calculations. Knowledge of the latent heat of vaporization can be of particular value when dealing with a material for which complete enthalpy data are not available. A method has been developed for making accurate reliable estimates of the latent heat of vaporization when only the vapor pressure and the critical constants of the material are known.     

AN IMPROVED GENERALIZED WATSON EQUATION FOR PREDICTION OF LATENT HEAT OF VAPORIZATION

In this paper, an improved generalized Watson equation for the prediction of latent heats of vaporization at any temperature in the two-phase region for any substance has been proposed. Generalized relations for exponents n₁, and n_2, have also been established, respectively.

In the current work, the latent heats of vaporization calculated with the proposed equation are compared with corresponding experimental values presented in the literature for 108 substances involving a total of 3361 points. These comparisons are further examined using the results of the original Watson equation and three other well-known equations available in the literature. The results of these comparisons indicate that the proposed equation is more accurate than the other four equations.     

AN IMPROVED GENERALIZED WATSON EQUATION FOR PREDICTION OF LATENT HEAT OF VAPORIZATION

In this paper, an improved generalized Watson equation for the prediction of latent heats of vaporization at any temperature in the two-phase region for any substance has been proposed. Generalized relations for exponents n ₁, and n _2, have also been established, respectively.

In the current work, the latent heats of vaporization calculated with the proposed equation are compared with corresponding experimental values presented in the literature for 108 substances involving a total of 3361 points. These comparisons are further examined using the results of the original Watson equation and three other well-known equations available in the literature. The results of these comparisons indicate that the proposed equation is more accurate than the other four equations.     

APPARATUS FOR MEASURING THERMAL CONDUCTIVITY OF REFRACTORIES*

An apparatus for measuring the thermal conductivity of refractories, is described in detail, and results are shown for several types of insulating refractories. Comparisons are madc from data which were obtained on a low-temperature plate tester, and the effect of several variables on measured heat flow are discussed.     

横掠螺旋翅片管管束对流换热的试验研究

本文在考虑影响气体横掠螺旋翅片管管束的对流换热的诸因素的基础上,使用两相闭式热虹管为传热元件,根据等雷诺数法的原则,通过试验及数据处理,对传热特性和阻力特性进行了分析和研究,并提出相应的数学准则式,这些公式可为设计提供依据。     

定热通量加热下微三角形槽道中滑移流动的换热特性

微三角形截面通道是现代工程实际应用中常涉及到的流动通道.针对微三角形槽道利用正交函数法求解了滑移流区内带温度跳跃边界条件的能量方程,对不可压缩气体在微三角形槽道内充分发展层流滑移流动的换热特性进行了理论分析,获得了轴向定热通量加热、周向均匀壁面温度条件下微三角形槽道内的温度分布和换热特性的分析解.计算结果表明：正交函数法适用于微三角形槽道内滑移流动换热特性的分析计算;在滑移流区,微三角形槽道内的平均Nusselt数随Knudsen数的增加而减小,其随高宽比变化的分布曲线随Knudsen数的增加而平行下移,Nusselt数比随Knudsen数的变化关系基本不受高宽比的影响.     

纵流壳程换热器的三维流场

根据纵流壳程换热器的结构特点和流动特点,提出其简化的物理模型;基于黏性流体力学基本方程,建立了流体流动和传热的数学模型;采用Galerkin有限元法,利用算子分裂思想,推导出离散化方程组. 为了验证数值模拟的正确性,利用两维激光多普勒测速仪对纵流壳程换热器 7个截面上壳程流体的流速进行了测试,将数值解和实验解进行比较,误差控制在7%～20%,两者基本吻合.实验表明：将纵流壳程换热器分为进口段、周期性发展段、出口段3段进行数值模拟是可行的;数值计算理论和程序是正确的.     

AN APPARATUS FOR MEASURING THE ABRASIVE HARDNESS OF GLAZES1

An apparatus for measuring the resistance to abrasion, or scratching, of glazes and possibly other materials is described. It provides, essentially, for the wearing away of the surface by means of standard cement sand, which is allowed to run through a funnel adjusted to deliver a definite amount of sand for a given time interval, and to strike the inclined surface of the test piece after falling a fixed distance. The loss in weight under this treatment is assumed to bear a definite relation to the resistance to abrasion.