Anatomy of the pressure adjustment method of condenser for small chiller

Update:22-02-2020
Summary:

During small chiller operation, changes in temperature […]

During small chiller operation, changes in temperature will cause changes in condensing pressure. Especially the high condensing pressure in summer will lead to the continuous increase of the power consumption of the compressor, leading to the gradual decline of the cooling capacity, which will indirectly make the low-temperature chiller circulatory worse. It is necessary to properly reduce the condensing pressure.

Then, the condensing pressure of the unit is too low in winter, the power supply of the throttle valve is insufficient, and the high-pressure liquid pipe is continuously affected by heating factors. They will reduce the capacity of the throttle valve, so the condensation pressure of the low-temperature chiller needs to be controlled. Therefore, it is imperative to control the condensation pressure all year round.

The condenser's pressure can be controlled by adjusting the heat exchange capacity of the condenser. When the heat exchange of the condenser increases, the gas discharged from the compressor (scroller \ piston) can be fully condensed, and the condensation pressure gradually decreases; if the heat exchange performance of the condenser is weakened, the condensation pressure is continuously increased.

For example: a water-cooled condenser can regulate the cooling water flow to control the condensing pressure. Install a regulating valve on the condenser cooling water outlet pipe. There are two modes of water volume regulating valve: one is the temperature type water volume regulating valve which sends the temperature indirectly from the cooling water outlet of the condenser. It has a temperature sensing bag that plugs into the condensate outlet. When the water temperature rises, the valve opens large; when the water temperature decreases, the valve closes small. The other is a pressure type water volume regulating valve that sends a signal directly from the condensing pressure, which leads to a pressure signal from the condenser. When the condensing pressure gradually increases, the valve opens; when the condensing pressure decreases, the valve closes, thereby changing the cooling water flow of the condenser.

There is also a special case: the water-cooled condenser uses a built-in cooling tower cooling water circulation system. In order to prevent the condensation pressure from being too low, a water bypass valve can be used to adjust. The water from the condenser is sent to the cooling tower for cooling. Part of it returns to the bypass back to the water inlet.

For large low-temperature chiller units, if multiple cooling water pumps are used to supply water to the water condenser in parallel, the number of pumps can be changed to adjust the cooling water flow according to the continuous change of the condensing pressure.