CHAPTER 6 REFRIGERATION AND AIR CONDITIONING
As an EN1 or ENC you have already learned the principles of refrigeration and air condition-ing, and the components and accessories that make up the system. You have learned how to start, operate, and secure refrigeration plants. In addition, you have performed routine maintenance jobs such as trouble shooting, and servicing the system, and used correct procedurersquo;s for leak detecting, and changing the lubricating oil in refrigeration compressors. As you advance in rate, you will be expected to have a greater knowledge of the construction and operating principles of refrigerating equipment. You will be required to perform more complicated maintenance jobs, to make repairs as required, and to determine the causes of inefficient plant operation and accomplish the necessary corrective procedures.
This chapter provides information that supplements related information in other training manuals applicable to your rating and related to the qualifications for advancement. Information is included on the construction and maintenance of refrigeration and air conditioning equipment, and the detection and correction of operating difficulties.
You should refer to the manufacturerrsquo;s technical manual for details of the plant on your ship.
The main parts of an R-12 refrigeration system are shown in figure 6-1. The primary components of the system are the thermostatic expansion valve, the evaporator, the compressor, the condenser, and the receiver. Additional equipment required to complete the plant includes piping, pressure gages, thermometers, various types of control switches and control valves, strainers, relief valves, sight-flow indicators, dehydrators, and charging connections.
In the following discussion, we will deal with the R-12 system as though it had only one evaporator, one compressor, and one condenser. However, a refrigeration system may (and usually does) include more than one evaporator, and it may include additional compressor and condenser units.
COMPRESSORS
Many different types and sizes of compressors are used in refrigeration and air conditioning systems. They vary from the small hermetic units used in drinking fountains and refrigerators, to the large centrifugal units used for air conditioning.
One of the most commonly encountered compressors on todayrsquo;s modern ships is a high speed, continuous running unit with a variable capacity. This compressor is of the multicylinder, reciprocating design, with a positive unloaded system built into the compressor to control the compressorrsquo;s capacity.
SHAFT SEALS
Where the crankshaft extends through the crankcase, a leakproof seal must be maintained to prevent the refrigerant and oil from escaping and also to prevent air from entering the crankcase when the pressure in the crankcase is lower than the surrounding atmospheric pressure. This is accomplished by crankshaft seal assemblies. There are several types of seals including the rotary seal, and the diaphragm.
The rotary seal shown in figure 6-2 consists of a stationary cover plate and gasket, a rotating assembly which includes a carbon ring, a neoprene seal, a compression spring, and compression washers. The sealing points are located (1) between the crankshaft and the rotating carbon rings, and sealed by a neoprene ring; (2) between the rotating carbon ring and the cover plate, and sealed by lapped surfaces; and (3) between the cover plate and the crankcase, and sealed by a metallic gasket. The seal is adjusted by adding or removing metal washers between the crankshaft shoulder and the shaft seal compression spring.
A stationary bellows seal is illustrated in figure 6-3. It consists of a bellows clamped to the com-pressor housing at one end to form a seal against a rotating shaft seal collar on the other. The sealing points are located (1) between the crankcase and the bellows, and sealed by the cover plate gasket; (2) between the crankshaft and the shaft seal collar, and sealed by a neoprene gasket; and
(3) between the surface of the bellows nose and the surface of the seal collar, and sealed by lapped surfaces. The stationary bellows seal is factory set for proper tension and should not be altered.
The rotating bellows seals, figure 6-4, consists of a bellows clamped to the crankshaft at one end to form a seal against a stationary, removable shaft seal shoulder on the other end. The sealing points are located (1) between the crankshaft and bellows, and sealed by a shaft seal clamping nut; (2) between the removable shaft seal shoulder and the crankcase and sealed by a neoprene gasket; and (3) between the bellows nose piece and the shaft seal collar, and sealed by lapped surfaces. This type seal is also factory set.
The diaphragm seal, figure 6-5, consists of a diaphragm clamped to the crankcase at its outer circumference and to a fulcrum ring at its center. The fulcrum ring forms a seal collar which is locked to the diaphragm. The sealing points are located (1) between the outer circumference of the diaphragm and the crankcase, and sealed by a copper ring gasket; (2) between the fulcrum ring and the diaphragm—sealed at the factory and not to be broken; (3) between the fulcrum ring and the rotating shaft seal collar, and sealed by lapped surfaces; and (4) between the shaft seal collar and the crankshaft shoulder, also sealed by lapped surfaces.
The tension in a diaphragm seal is adjusted by adding or removing diaphragm-to-crankcase gaskets to obtain the specified deflection. For information on handling, cleaning, and replacement of shaft seal assemblies, consult the manufacturerrsquo;s technical manual or the directions enclosed with every new seal.
CAPACITY CONTROL
Controlling the capacity of the compressor is accomplished by unloading and loading the cylinders. This is a very desirable design feature of the unit, because if
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CHAPTER 6 REFRIGERATION AND AIR CONDITIONING
As an EN1 or ENC you have already learned the principles of refrigeration and air conditioning, and the components and accessories that make up the system. You have learned how to start, operate, and secure refrigeration plants. In addition, you have performed routine maintenance jobs such as trouble shooting, and servicing the system, and used correct procedurersquo;s for leak detecting, and changing the lubricating oil in refrigeration compressors. As you advance in rate, you will be expected to have a greater knowledge of the construction and operating principles of refrigerating equipment. You will be required to perform more complicated maintenance jobs, to make repairs as required, and to determine the causes of inefficient plant operation and accomplish the necessary corrective procedures.
This chapter provides information that supplements related information in other training manuals applicable to your rating and related to the qualifications for advancement. Information is included on the construction and maintenance of refrigeration and air conditioning equipment, and the detection and correction of operating difficulties.
You should refer to the manufacturerrsquo;s technical manual for details of the plant on your ship.
The main parts of an R-12 refrigeration system are shown in figure 6-1. The primary components of the system are the thermostatic expansion valve, the evaporator, the compressor, the condenser, and the receiver. Additional equipment required to complete the plant includes piping, pressure gages, thermometers, various types of control switches and control valves, strainers, relief valves, sight-flow indicators, dehydrators, and charging connections. 第六章 制冷和空调
作为工程师或工程指挥，你已经学习了制冷和空调的原理，以及组成系统的组件和附件。你已经学习了如何启动、操作和保护制冷工厂。此外，你还进行了日常的维护工作，如故障排除、系统维护、泄漏检测、制冷压缩机润滑油更换等。随着你的进步，你将会对制冷设备的结构和工作原理有更多的了解。你将被要求执行更复杂的维修工作，根据需要进行维修，并确定低效的工厂运行的原因和完成必要的纠正程序。
本章提供的信息补充了其他适用于你的评级和与晋升资格相关的培训手册中的相关信息。资料包括制冷和空调设备的建造和维修，以及操作困难的发现和纠正。
有关船上工厂的详细情况，请参阅制造商的技术手册。
R-12制冷系统的主要部件如图6-1所示。该系统的主要部件是恒温膨胀阀、蒸发器、压缩机、冷凝器和接收机。完成工厂所需的额外设备包括管道、压力计、温度计、各种类型的控制开关和控制阀、过滤器、安全阀、视流量指示器、脱水器和充电连接。
In the following discussion, we will deal with the R-12 system as though it had only
one evaporator, one compressor, and one condenser. However, a refrigeration system may (and usually does) include more than one evaporator, and it may include additional compressor and condenser units.
COMPRESSORS
Many different types and sizes of compressors are used in refrigeration and air conditioning systems. They vary from the small hermetic units used in drinking fountains and refrigerators, to the large centrifugal units used for air conditioning.
One of the most commonly encountered compressors on todayrsquo;s modern ships is a high speed, continuous running unit with a variable capacity. This compressor is of the multicylinder, reciprocating design, with a positive unloaded system built into the compressor to control the compressorrsquo;s capacity.
SHAFT SEALS
Where the crankshaft extends through the crankcase, a leakproof seal must be maintained to prevent the refrigerant and oil from escaping and also to prevent air from entering the crankcase when the pressure in the crankcase is lower than the surrounding atmospheric pressure. This is accomplished by crankshaft seal assemblies. There are several types of seals including the rotary seal, and the diaphragm.
The rotary seal shown in figure 6-2 consists of a stationary cover plate and gasket, a rotating assembly which includes a carbon ring, a neoprene seal, a compression spring, and compression washers. The sealing points are located (1) between the crankshaft and the rotating carbon rings, and sealed by a neoprene ring; (2) between the rotating carbon ring and the cover plate, and sealed by lapped surfaces; and (3) between the cover
在接下来的讨论中，我们将把R-12系统当作只有一个蒸发器、一个压缩机和一个冷凝器来处理。然而，一个制冷系统可以(通常是)包括多个蒸发器，它可以包括额外的压缩机和冷凝器单元。
压缩机
许多不同类型和尺寸的压缩机用于制冷和空调系统。它们从用于饮水机和冰箱的小型密封装置，到用于空调的大型离心装置，不一而足。
当今现代船舶上最常见的压缩机之一是一种具有可变容量的高速连续运行机组。该压缩机为多缸往复设计，压缩机内置正卸荷系统，控制压缩机的容量。
轴密封
当曲轴伸入曲轴箱时，必须保持密封密封，防止制冷剂和机油泄漏，当曲轴箱压力低于周围大气压时，防止空气进入曲轴箱。这是由曲轴密封组件完成的。有几种类型的密封，包括旋转密封和隔膜。
图6-2所示的旋转密封由一个固定盖板和垫圈、一个包括碳环、氯丁橡胶密封、压缩弹簧和压缩垫圈的旋转组件组成。所述密封点位于(1)曲轴与所述旋转碳环之间，并用氯丁橡胶环密封;(2)旋转碳环与盖板之间，采用搭接表面密封;(3)在盖板和曲轴箱之间，用金属垫圈密封。通过在曲轴肩部和轴密封压缩弹簧之间增加或减少金属垫圈来调整密封。
plate and the crankcase, and sealed by a metallic gasket. The seal is adjusted by adding or removing metal washers between the crankshaft shoulder and the shaft seal compression spring.
A stationary bellows seal is illustrated in figure 6-3. It consists of a bellows clamped to the compressor housing at one end to form a seal against a rotating shaft seal collar on the other. The sealing points are located (1) between the crankcase and the bellows, and sealed by the cover plate gasket; (2) between the crankshaft and the shaft seal collar, and sealed by a neoprene gasket; and(3)between the surface of the bellows nose and the surface of the seal collar, and sealed by lapped surfaces. The stationary bellows seal is factory set for proper tension and should not be altered.
The rotating bellows seals, figure 6-4, consists of a bellows clamped to the crankshaft at one end to form a seal against a stationary, removable shaft seal shoulder on the other end. The sealing points are located (1) between the crankshaft and bellows, and sealed by a shaft seal clamping nut; (2)between the removable shaft seal shoulder and the crankcase and sealed by a neoprene gasket; and (3) between the bellows nose piece and the shaft seal collar, a
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