制冷系统中的载冷剂----外文翻译.doc
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制冷系统中的载冷剂----外文翻译,载冷剂是一种液体，它被用做热传递的流体，而且当得到或失去热量又不改变其状态时，它可以改变温度。对于低温制冷剂，就是需要一种冰点比水的还低的载冷剂。在这一章中，将讨论各部分设计过程中要考虑的问题、所要求的系统参数，以及载冷剂的应用。（相关内容可查阅1997年《ashrae handbook—fundamentals》的第...
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载冷剂是一种液体，它被用做热传递的流体，而且当得到或失去热量又不改变其状态时，它可以改变温度。对于低温制冷剂，就是需要一种冰点比水的还低的载冷剂。在这一章中，将讨论各部分设计过程中要考虑的问题、所要求的系统参数，以及载冷剂的应用。（相关内容可查阅1997年《ASHRAE Handbook—Fundamentals》的第二、三、十九、二十和三十三章）。
载冷剂的选择
为了保证最大组成部件的可靠性及使用寿命，在任意温度、压力下，载冷剂与系统中的其它物质必须都能够共存，还应符合环境要求、遵守应用中的安全规则。而且，使用和贮存也要比较经济。
载冷剂应具有-50F的最低冰点温度，最好可以把它置于-150F的最低温度下。当载冷剂降至系统中的最低温度时，它的温度就足够低了，可以达到满意的热传递效果和合理的压降了。
A secondary coolant is a liquid that is used as a heat transfer fluid and that changes temperature as it gains or loses heat energy without changing into another phase. For the lower temperatures of refrigeration, this requires a coolant with a freezing point below that of water. In this chapter, the design considerations for components system performance requirements, and applications for secondary coolants are discussed. Related information can be found in Chapters 2,3,19,20, and 33 of the 1997 ASHRAE Handbook—Fundamentals.
COOLANT SELECTION
A secondary coolant must be compatible with the other materials in the system at the pressures and temperatures encountered for maximum component reliability and operating life. The coolant should also be compatible with the environment and the applicable safety regulations, and it should be economical to use and replace.
The coolant should have a minimum freezing point of 50F below and preferably 150F below the lowest temperature to which it will be exposed. When subjected to the lowest temperature in the system, the viscosity of the coolant should be low enough to allow satisfactory heat transfer and reasonable pressure drop.
The vapor pressure of the coolant should not exceed that allowed at the maximum temperature encountered. To avoid a vacuum in a low vapor pressure secondary coolant system, the coolant can be pressurized with pressure-regulated dry nitrogen in the expansion tank. However some special secondary coolant such as those used for computer circuit cooling have a high solubility for nitrogen and must therefore be isolated from the nitrogen with a suitable diaphragm.
载冷剂的选择
为了保证最大组成部件的可靠性及使用寿命，在任意温度、压力下，载冷剂与系统中的其它物质必须都能够共存，还应符合环境要求、遵守应用中的安全规则。而且，使用和贮存也要比较经济。
载冷剂应具有-50F的最低冰点温度，最好可以把它置于-150F的最低温度下。当载冷剂降至系统中的最低温度时，它的温度就足够低了，可以达到满意的热传递效果和合理的压降了。
A secondary coolant is a liquid that is used as a heat transfer fluid and that changes temperature as it gains or loses heat energy without changing into another phase. For the lower temperatures of refrigeration, this requires a coolant with a freezing point below that of water. In this chapter, the design considerations for components system performance requirements, and applications for secondary coolants are discussed. Related information can be found in Chapters 2,3,19,20, and 33 of the 1997 ASHRAE Handbook—Fundamentals.
COOLANT SELECTION
A secondary coolant must be compatible with the other materials in the system at the pressures and temperatures encountered for maximum component reliability and operating life. The coolant should also be compatible with the environment and the applicable safety regulations, and it should be economical to use and replace.
The coolant should have a minimum freezing point of 50F below and preferably 150F below the lowest temperature to which it will be exposed. When subjected to the lowest temperature in the system, the viscosity of the coolant should be low enough to allow satisfactory heat transfer and reasonable pressure drop.
The vapor pressure of the coolant should not exceed that allowed at the maximum temperature encountered. To avoid a vacuum in a low vapor pressure secondary coolant system, the coolant can be pressurized with pressure-regulated dry nitrogen in the expansion tank. However some special secondary coolant such as those used for computer circuit cooling have a high solubility for nitrogen and must therefore be isolated from the nitrogen with a suitable diaphragm.
