graetz number

简明释义

格雷茨数

英英释义

例句

1.A low graetz number 格雷茨数 indicates a fully developed flow, which simplifies thermal calculations.

低graetz number 格雷茨数 表明流动已完全发展，这简化了热计算。

2.In fluid dynamics, the graetz number 格雷茨数 helps predict the development of thermal boundary layers.

在流体动力学中，graetz number 格雷茨数 有助于预测热边界层的发展。

3.Engineers often refer to the graetz number 格雷茨数 when designing systems that involve convective heat transfer.

工程师在设计涉及对流热传递的系统时，常常参考graetz number 格雷茨数。

4.The calculation of the graetz number 格雷茨数 is crucial for determining the heat transfer efficiency in a heat exchanger.

计算graetz number 格雷茨数 对于确定热交换器的热传递效率至关重要。

5.To optimize the heat exchanger design, one must consider the graetz number 格雷茨数 along with the Reynolds number.

为了优化热交换器设计，必须考虑graetz number 格雷茨数 和雷诺数。

作文

The study of heat transfer is crucial in various engineering applications, especially in the design of heat exchangers and other thermal systems. One important parameter that engineers often consider when analyzing heat transfer in ducts or channels is the graetz number. The graetz number is a dimensionless quantity that characterizes the relative importance of conduction and convection in heat transfer processes. It provides insight into how effectively heat is being transferred through a fluid flowing in a conduit. To understand the significance of the graetz number, we must first delve into the principles of heat transfer. Heat transfer can occur through three primary mechanisms: conduction, convection, and radiation. In many practical applications, particularly in duct flow, conduction and convection are the most relevant mechanisms. Conduction is the process of heat transfer through a solid material, while convection involves the movement of heat through a fluid (liquid or gas) due to the motion of the fluid itself.The graetz number is defined as the ratio of the thermal entry length to the characteristic length of the flow system. Mathematically, it can be expressed as: Gz = (L / D) * (Nu / Pr) where L is the length of the duct, D is the diameter of the duct, Nu is the Nusselt number, and Pr is the Prandtl number. This equation shows that the graetz number depends on both the geometry of the system and the properties of the fluid involved. In practical terms, a low graetz number indicates that conduction dominates the heat transfer process, which typically occurs in shorter ducts or at lower flow rates. Conversely, a high graetz number suggests that convection plays a more significant role, which is common in longer ducts or at higher flow rates. Understanding the implications of the graetz number helps engineers optimize designs for efficient heat transfer. For instance, in the design of a heat exchanger, engineers must ensure that the graetz number is within an appropriate range to maximize thermal efficiency. If the graetz number is too low, heat transfer may be insufficient, leading to poor performance. On the other hand, if it is too high, it may indicate excessive turbulence, which could result in increased pressure drops and energy losses. In conclusion, the graetz number is a vital concept in the field of heat transfer engineering. By understanding this dimensionless parameter, engineers can make informed decisions regarding the design and operation of thermal systems. Its relevance spans across various applications, from HVAC systems to chemical reactors, making it an essential tool in the pursuit of efficient energy management. As technology advances and the demand for energy efficiency increases, the importance of the graetz number will continue to grow, guiding engineers in their efforts to innovate and improve thermal systems worldwide.

热传递的研究在各种工程应用中至关重要，尤其是在换热器和其他热系统的设计中。工程师在分析管道或通道中的热传递时，常常考虑的一个重要参数是Graetz数。Graetz数是一个无量纲量，它表征了导热与对流在热传递过程中的相对重要性。它提供了对流体在导管中流动时热量传递有效性的洞察。要理解Graetz数的重要性，我们必须首先深入了解热传递的原理。热传递可以通过三种主要机制发生：导热、对流和辐射。在许多实际应用中，特别是在管道流动中，导热和对流是最相关的机制。导热是通过固体材料传递热量的过程，而对流则涉及到由于流体自身运动而通过流体（液体或气体）移动的热量。Graetz数被定义为热入口长度与流动系统特征长度的比率。从数学上讲，它可以表示为：Gz = (L / D) * (Nu / Pr)其中L是管道的长度，D是管道的直径，Nu是努塞尔特数，Pr是普朗特数。这个方程显示了Graetz数依赖于系统的几何形状和所涉及流体的性质。在实际应用中，低Graetz数表明导热在热传递过程中占主导地位，这通常发生在较短的管道或较低的流速下。相反，高Graetz数则表明对流起着更重要的作用，这在较长的管道或较高的流速下很常见。理解Graetz数的含义有助于工程师优化设计以实现高效的热传递。例如，在换热器的设计中，工程师必须确保Graetz数处于适当范围内，以最大限度地提高热效率。如果Graetz数过低，热传递可能不足，导致性能不佳。另一方面，如果过高，则可能表明过度湍流，这可能导致压力损失和能量损失的增加。总之，Graetz数是热传递工程领域的重要概念。通过理解这一无量纲参数，工程师可以就热系统的设计和运行做出明智的决策。它的相关性跨越了从暖通空调系统到化学反应器的各种应用，使其成为追求高效能源管理的基本工具。随着技术的进步和对能源效率需求的增加，Graetz数的重要性将继续增长，引导工程师在全球范围内创新和改善热系统。