Dissection of pressure regulation mode for condenser of small chiller

Update:01 Jul 2020
Summary:

In the operation of small chiller, the change of temper […]

In the operation of small chiller, the change of temperature will cause the change of condensation pressure. Especially in summer, the high condensing pressure will lead to the continuous increase of compressor power consumption, resulting in the gradual decrease of refrigeration capacity, which indirectly makes the circulation of low-temperature water chiller worse. Therefore, it is necessary to reduce the condensing pressure properly.
Then, in winter, the condensing pressure of the unit is too low, the power of throttle valve is not sufficient, and the high-pressure liquid pipe is affected by heating factors, they will reduce the capacity of throttle valve, so it is necessary to control the condensation pressure of low-temperature water chiller. Therefore, annual control of condensation pressure is imperative.

The pressure of the condenser can be controlled by adjusting the heat exchange capacity of the condenser. When the heat transfer of the condenser increases, the gas discharged from the compressor (scroll / piston) can be fully condensed, and the condensation pressure will gradually decrease; if the heat transfer performance of the condenser is weakened, the condensing pressure will continue to rise.
For example: water cooled condenser can adjust the cooling water flow and control the condensation pressure. Install the regulating valve on the outlet pipe of condenser cooling water. There are two modes of water regulating valve: one is the temperature type water regulating valve which sends the signal indirectly by the temperature at the outlet of condenser cooling water. It has a temperature sensing package, which is inserted into the condensate outlet. When the water temperature increases, the valve opens up; when the water temperature decreases, the valve closes down. The other is the pressure type water regulating valve which directly sends the signal of condensation pressure, which leads to the pressure signal from the condenser. When the condensing pressure gradually increases, the valve opens up; when the condensation pressure decreases, the valve closes down, thus changing the cooling water flow of the condenser.

There is also a special case: the water-cooled condenser adopts its own cooling tower cooling water circulation system. In order to prevent the condensation pressure from being too low, the water bypass valve can be used to regulate. It makes part of the water from the condenser send to the cooling tower for cooling, and the other part returns to the bypass water inlet.
For large-scale low-temperature chiller units, if several cooling water pumps are used to supply water to the water condenser in parallel, the number of pumps can be changed according to the continuous change of condensation pressure to adjust the cooling water flow.

Shanghai Zhaoxue Refrigeration Equipment Co., Ltd.