水冷冷却器设计数据

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水冷式冷水机组的设计数据。在这篇文章中we are going to be taking a very detailed look at the design data for a centrifugal, water cooled, chiller. This is a pretty advanced chiller video, so if you’re new to the topic then I highly recommend you start from the基础首先。

滚动到底部以观看在冷却器设计数据上的YouTube教程视频。

我想强调这只是设计数据。每次冷却器都不同,您应该与您的制造商交谈相关信息。结果将因现实世界而异,也有加载。

在上面的图示中,我们已经显示了主冷水机组成分。该压缩机, which is the driving force of the refrigerant around the system.冷凝器从系统中消除不需要的热量并将其发送到冷却塔。该expansion valve它扩展了制冷剂并将过热器控制到压缩机中the evaporator它收集来自建筑物的不需要的热量并产生冷冻水。

我们将在这两个图表上查看所有点,以查看该系统周围的压力,温度,焓和熵。左侧图表是我们的温度V的熵图,右侧图表是我们的压力V的焓图。

  • Point 1 is just before the compressor, and the exit of the evaporator. That will be a low pressure, low temperature saturated / slightly superheated vapor.
  • Point 2 is just after the compressor, before the condenser. That’s a high pressure, high temperature superheated vapor.
  • Point 3 is just after the condenser, but before the expansion valve. That’s going to be a high pressure, medium temperature saturated liquid.
  • Point 4 is just after the expansion valve but before the evaporator. This will be a low pressure, low temperature and it’s going to be a mix between a liquid and vapor.

压缩机

在该示例中,压缩机正在推动制冷剂,其流速为16.5kg / s(36.4LBm / s)。然后,电动机消耗425.9千瓦,压缩机运行100%负载。如果冷却器在零件负载下运行,则该值将不同。

该refrigerant is being sucked in from the evaporator (Point 1) at around 356 kPa (3.56 Bar) and at a temperature of 5.5 ° C (41.9 ° F). The refrigerant enthalpy is 402 kJ/kg (173 BTUs/lbm). The entropy will be 1.73 kJ/kg.K (0.41 BTUs/lbm.F).

该压缩机is compacting the refrigerant into a smaller space, and looking at our charts we know that the enthalpy is going to increase, the entropy is going to slightly increase and the pressure and temperature will massively increase.

当制冷剂(2)915 kPa (9.15 bar). The temperature reaches 43.6 ° C (110.5 ° F). The enthalpy is now 426 kJ/kg.K (183 Btu/lbm) and the entropy is now 1.74 kJ/kg.K (0.042 Btu/lbm.F).

记住进入冷凝器的制冷剂的温度必须高于传热的进入的冷凝器水温。如果它们是相同的温度,那么不会发生热传递,冷却器不会冷却。

Condenser

该next part we’ll look at is the condenser. In this example the condenser water is flowing through the condenser at 116.6 L/s (247 cfm). The condenser water is coming into the condenser, from the cooling tower, at 29 ° C (84.2 ° F). The refrigerant will then transfer the buildings unwanted heat into the condenser water. This will increase the temperature of the condenser water, so when it leaves to go back to the cooling tower it will be around 35 ° C (95 ° F).

现在,冷凝器中流速较高的原因比蒸发器比较,因为冷凝器必须拒绝更多的热量。它还必须从压缩机和机器的其他部件中脱离热量。

制冷剂来自压缩机,并在915kPa(9.15巴)的压力下进入冷凝器,温度为43.6°C(110.5°F),焓为426kJ / kg.k(183 btu / lbm)和一个1.74 kJ / kg.k的熵(0.428 btu / lbm.f)。

Once the refrigerant has give away some of its energy to the circulating condenser water, it will now leave as a liquid at 36.1 ° C (97 ° F) but still at the same pressure as it entered. It’s entropy will have dropped to 1.17 kJ.kg.K (0.28 BTU/lbm.F) and the enthalpy increases to 250 kJ/kg.K (107.5 BTU/lbm). It then enters into the expansion valve.

Expansion Valve

该expansion valve controls the flow of refrigerant, it measures the superheat on the suction line of the chiller and then reacts to this by allowing or restricting refrigerant flow to maintain a certain value. The refrigerant is entering the expansion valve as a liquid and leaving as a vapour/liquid mixture.

It enters, in this example, at a temperature of 36.1 ° C (97 ° F), a pressure of 915 kPa (9.15 Bar), the entropy is 1.17 kJ.kg.K (0.28 BTU/lbm.F) and the enthalpy is 250 kJ/kg.K (107.5 BTU/lbm).

制冷剂通过喷射制冷剂喷射的小孔膨胀。它将其扩展到更大的体积并导致压力下降,这使得它可以降低温度,因为它现在没有如此紧密包装。它将留在5.5°C(41.9°F)的温度下,压力为356 kPa(3.56 bar),从图表中我们知道它会保持相同的焓,但熵会略微变化,它会在1.20 kj留下/kg.k(0.29 btu / lbm.f)。

蒸发器

该evaporator generates the cold “chilled water” which cycles around the building, providing air conditioning and collecting the buildings unwanted heat. This now warm chilled water returns to the evaporator and transfers this heat into the refrigerant, the chilled water then leaves cooler and cycles around the building, meanwhile the refrigerant boils and carry’s the thermal energy to the compressor.

在该示例中,冷却的水流通过蒸发器,在每秒约99.5升约99.5升,约为每分钟210立方英尺。冷却水在约12℃(53.6°F)约为蒸发器。冷却水转移到制冷剂的热量后,它将将蒸发器留在约6°C(42.8°F)。

该refrigerant is picking up thermal energy but the temperature only changes slightly which confuses many people. The reason it doesn’t increase dramatically is because it is undergoing a phase change from a liquid to a vapour so the thermal energy is being used to break the bonds between the molecules. The enthalpy and entropy will increase and this is where the energy is going

当制冷剂叶时,在5.5℃(41.9°F),356 kPa(3.56 bar)的压力为402kJ / kg.k(173 btu / lbm)和1.73的焓KJ / kg.k(0.41 btu / lbm.f)。

然后,制冷剂返回压缩机以重新开始循环。


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