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。
- 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.
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).
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).
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.
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）。
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.
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）。