什么是换热器？
What Are Heat Exchangers?
热交换器是在不混合或混合流体的情况下在流体之间传递热量的装置。
Heat exchangers are devices that transfer heat between fluids without mixing or blending them.
流体由具有高导热性的壁隔开。
The fluids are separated by a wall that has high thermal conductivity.
壁的厚度旨在防止流体混合或它们之间直接接触的可能性。
The thickness of the wall is designed to prevent the mixing of the fluids or the possibility of direct contact between them.
该过程中包括一种工作介质，它可以从正在处理的液体中吸收或吸收热量。
Included in the process is a working media that rejects or absorbs heat from the liquid being processed.
该过程的*终结果是流体流的冷却或加热。
The resulting outcome of the process is the cooling or heating of the fluid stream.
换热器的数量无穷无尽，随着技术的进步和各种金属性能的提高，每年都会开发出新的换热器。
There are an endless number of heat exchangers, with new ones developed each year as technology improves and the properties of various metals advance.
热交换器中的传递涉及使用流体中的对流和热传导。
The transfer in a heat exchanger involves the use of convection in fluids and thermal conduction.
热交换器设计的讨论从传热系数开始，称为 U 系数，它是牛顿冷却定律的一种表达。
The discussion of the design of heat exchangers begins with the heat transfer coefficient, known as the U factor, which is an expression of Newton’s law of cooling.
此外，工程师使用平均温差 (LMTD) 来确定传热的温度驱动力。
Additionally, engineers use the mean temperature difference (LMTD) to decide on the temperature driving force for heat transfer.
流体可能具有相同或不同的相（例如液体到液体或蒸汽到液体），这些也被考虑在内。Fluids may have the same or different phases (such as liquid-to-liquid or vapor-to-liquid), that are also considered.
冷热流体可能被高导热壁（通常由钢管或铝管制成）隔开，也可能彼此直接接触。
The hot and cold fluids may be separated by a wall with high thermal conductivity (usually made of steel or aluminum tube), or they may have direct contact with each other.
热交换器有别于燃料、电力或核动力热传递设备，例如锅炉。
Heat exchangers differentiate themselves from fuel, electrical, or nuclear-powered heat transfer equipment, such as boilers.
热源和接受介质必须都是流体。
The heat source and receiving medium must be both fluids.
流体被定义为在施加的剪切应力或外力作用下流动的任何物质，包括液体、气体和蒸汽。
Fluids are defined as any substance that flows under applied shear stress or external force, which encompasses liquids, gasses, and vapors.
热交换器广泛用于许多行业，例如食品、制药、生物加工和化学制造，在这些行业中，加热或冷却是为进一步加工准备流体的*终或中间步骤。
Heat exchangers are widely used in many industries such as food, pharmaceutical, bioprocessing, and chemical manufacturing, where heating or cooling is the final or an intermediate step to prepare the fluids for further processing.
它们还可用于食品和药品中微生物的灭菌。
They can also be used in the sterilization of microorganisms in food and pharmaceutical products.
在许多情况下，热交换器的使用被认为是可行的。
There are many instances where the use of heat exchangers is deemed practical.
例如，发电厂和发动机的高温废气中含有大量的热量，可以通过在烟囱前安装热交换器来回收热量。
For instance, high-temperature exhaust gasses from power plants and engines contain a large amount of heat which can be recovered by installing a heat exchanger before the smokestack.
