制冷系统也可以用作热泵，其中有用的输出是the high-temperature heat rejected at the condenser. Alternatively, a refrigeration system can be used for providing cooling in summer and heating in winter. Such systems have been built and are available now

蒸汽压缩热力学循环

Most of the modern refrigerators work on this cycle, in Its simplest form, there are fourfundamental operations required to complete one cycle.

（a）压缩
(b) Condensation
(c) Expansion
(d) Vaporization

a) Compression

The low-pressure Vapour in the dry state is drawn from the evaporator during the suction stroke压缩机。在压缩冲程期间，压力和温度增加至蒸气temperature is greater than the temperature of condenser cooling medium (air orwater)

在point 1in the diagram, the circulating refrigerant enters the compressor as a saturated vapor. Frompoint 1到point 2，蒸汽是不正常压缩的（即，在恒定熵处压缩），并将压缩机作为过热的蒸气排出。

b) Condensation

当高压制冷剂蒸汽进入冷凝器热量从冷凝器流到cooling medium thus allowing the vaporized refrigerant to return to the liquid state.

Frompoint 2到point 3,蒸汽通过冷却蒸汽来通过冷却过热的电容器的一部分来移动。之间point 3andpoint 4, the vapor travels through the remainder of the condenser and is condensed into a saturated liquid. The condensation process occurs at essentially constant pressure.

c) Expansion

冷凝器后，液体制冷剂在液体接收机中储存在需要之前。来自receiver it passes through an expansion valve where the pressure is reduced sufficiently to允许在约-10℃的低温下蒸发液体。

之间要点4和5, the saturated liquid refrigerant passes through the expansion valve and undergoes an abrupt decrease of pressure. That process results in the adiabatic flash evaporation and auto-refrigeration of a portion of the liquid (typically, less than half of the liquid flashes).

d）蒸发

The low-pressure refrigerant vapor after expansion in the expansion valve enters the蒸发器或冷藏空间，其中大量的热量被其吸收refrigeration is furnished.

之间points 5 and 1, the cold and partially vaporized refrigerant travels through the coil or tubes in the evaporator where it is vaporized by the warm air (from the space being refrigerated) that a fan circulates across the coil or tubes in the evaporator.

所得到的制冷剂蒸气返回到压缩机入口处point 1到complete the thermodynamic cycle.

蒸汽压缩制冷循环的主要部分：

1. Evaporator

Its function is to provide a heat transfer surface through which heat can pass from therefrigerated space into the vaporizing refrigerant.

This is generally a翅片管（头发销型）热交换器, similar to Air-Cooled Condensers.

2.吸入线

It carries the low-pressure vapor from the evaporator to suction inlet of the compressor.

3.压缩机

The function of the compressor is to draw refrigerant vapor from the evaporator and to raise Itstemperature and pressure to such a print to that it may be easily condensed with normallyavailable condensing media. It also maintains a continuous flow of the refrigerant through thesystem.

压缩率=绝对排出压力/绝对吸入压力

The Capacity of a Compressor is determined by its Mass Flow rate (Lb/Min) and not by Volume Flow(CFM).

The most common compressors used in chillers are往复式，旋转螺钉，离心机和涡旋式压缩机。Each application prefers one or another due to size, noise, efficiency and pressure issues.

4. Discharge Line

It conveys the high pressure and high-temperature refrigerant from the compressor to thecondenser.

5.。Condenser

The function of the condenser is to provide a heat transfer surface through which heat passes从制冷剂到冷凝介质，含水或空气。

Types of Condensers:
•空气冷却
• 水冷

6. Liquid Receiver

It acts as, a reservoir that stores the liquid refrigerant coming from the condenser andsupplies it to the evaporator according to the requirement.

7. Liquid Line

它带有从接收器的液体制冷剂，并将其传送到膨胀阀。

8. Expansion valve

Function Of This valve is to Supply a proper amount of refrigerant to the evaporator after reducing its大大压力使得制冷剂可以从中取出足够量的热量蒸发过程中的制冷空间

计量装置转换和高压力High-Temperature Liquid from Condenser to Low Pressure and Low-Temperature Liquid-Vapor mixture, which will be fed to the Evaporator.

An expansion valve is a component in refrigeration and air conditioning systems that controls the amount of refrigerant flow into the evaporator thereby controlling the superheat at the outlet of the evaporator.

Types of Expansion devices

• Thermostatic EV
• Capillary tube
• 手动运营的ev.
• Automatic or Constant Pressure EV
• Float expansion

Types of Vapor Compression Cycles :

我们已经废弃了蒸汽压缩周期基本上由压缩，冷凝，节流和蒸发组成。许多科学家们注重他们的注意力增加了循环的性能系数。通过许多周期，但以下是来自主题的观点很重要：

1. Cycle with dry saturated vapor after compression,
2.压缩后用湿蒸汽循环，
3. Cycle with superheated vapor after compression,
4.压缩前用过热蒸气循环，
5.。Cycle with under cooling or sub cooling of refrigerant,

Advantages of Vapour Compression System :

• It has a smaller size for the given capacity of refrigeration.
• It has less running cost.
• 它可以在大量温度范围内使用。
• The coefficient of performance is quite high.
• Less time required to produce refrigerant effects.

Disadvantages of Vapour Compression System :

• 初始成本很高。
• The prevention of leakage of the refrigerant is the major problem in the vapor compression system.
• 移动部件引起的磨损和噪音
• 吸入管线中的液滴可能损坏。

多级：在制冷系统的情况下，非常低压制冷剂蒸气（蒸发器压力）将被压缩到非常高压的制冷剂蒸气（冷凝器压力）。由于该压力比非常高，在单级的情况下，所需的尺寸和工作是较多的，因此COP减少以增加COP并减少所需的工作，需要多阶段。

Advantages of multi-staging in vapor compression system:

蒸汽压缩系统多分数的优点是：

1.每千克制冷剂完成的工作通过使用中间冷却器减少
2. Volumetric efficiency of compressor increases
3. It reduces leakage of refrigerant
4. It gives uniform torque, therefore, the smaller flywheel may be used
5.可以完成有效的润滑
6. Cost of compressor reduces

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更多资源/文章

制造技术Notes , Articles

RAC / HVAC - Articles , Notes , Que and Answers

Mechanical Subjectwise Basic Concept Notes ,Articles

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