8/24/2015

shell-and-tube evaporator of chiller trane

shell-and-tube evaporator  
of chiller trane



trane chiller


Components:
By removing the vapor portion of the mixture before it gets to the evaporator the separator enhances the effectiveness of the evaporation process.


Flooded Evaporator

Evaporator:
In the flooded shell-and-tube evaporator cool, low-pressure liquid refrigerant enters the distribution system inside the shell and is distributed uniformly over the tubes, absorbing heat from relatively warm water that flows through the tubes. This transfer of heat boils the film of liquid refrigerant on the tube surfaces and the resulting vapor is drawn back to the compressor. The cooled water can now be used in a variety of comfort or process applications.
A sensor can monitor the level of liquid refrigerant in this type of evaporator and the electronic expansion valve can be used to carefully meter the liquid refrigerant flow to the evaporator’s distribution system in order to maintain a relatively low level of refrigerant in the evaporator shell.

Direct Expansion Evaporator
direct expansion (DX) shell-and-tube evaporator:
Another type of evaporator found in helical-rotary chillers is the direct expansion (DX) shell-and-tube evaporator. In this type of evaporator the cool, low-pressure liquid refrigerant flows through the tubes and water fills the surrounding
shell. As heat is transferred from the water to the refrigerant, the refrigerant boils inside the tubes and the resulting vapor is drawn to the compressor. Baffles within the shell direct the water in a rising and falling flow path over the tubes that carry the refrigerant. The resulting turbulence improves heat transfer.
Since the tubes of a flooded evaporator contain water, they can be mechanically cleaned without removing the refrigerant charge. The tubes of a direct expansion evaporator must be chemically cleaned. Additionally, flooded evaporators are typically more effective, but are more costly.

Controls And Starter
Controls and Starter:
A microprocessor-based control panel is provided on the chiller to provide accurate chilled water control as well as monitoring, protection, and adaptive limit functions. These controls monitor the chiller’s operation and prevent the chiller from operating outside of its limits. They can compensate for unusual operating conditions while keeping the chiller running by modulating system components, rather than simply tripping off due to a safety setting.
Furthermore, when problems do occur, diagnostic messages aid in troubleshooting.
This control system not only provides accurate, optimized control and protection for the chiller, but permits interfacing with a building automation system for integrated system control. In a chilled water system, optimal control is a system-wide issue, not just a chiller issue.


Because compressor motors create such a large electrical load, they cannot be started and stopped using a simple switch or plug. A starter provides a linkage between the motor and the electrical distribution system. Its primary function is to connect (start) and disconnect (stop) the chiller from the line. The starter also includes a transformer that provides power to the chiller control panel and components to perform overload protection and current-limiting functions.
Finally, the application of a chiller starter also requires considering a means of disconnect and short circuit protection.
                                                                abo bahaa eddine

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