4/22/2021 0 Comments York Centrifugal Chiller Manual
The first section (outside the refrigerant dome) is the desuperheating process.
![]() Most design engineers will sooner or later use centrifugal chillers to meet their design needs. The heat is used to boil the refrigerant changing it from a liquid to a gas. McQuay Distinction chillers use a flooded type evaporator, which is very energy efficient. Flooded evaporators have the chilled water in the tubes and the refrigerant in the shell. Large chillers can have over five miles of tubing in their heat exchangers. York Centrifugal Chiller Series Chillers UseMcQuay Distinction series chillers use liquid refrigerant cooled hermetic electric motors (an industry first). The centrifugal compressor is a non-positive displacement type. It raises the pressure and temperature of the refrigerant by converting kinetic energy into pressure. In this case, it removes heat from the refrigerant causing it to condense from a gas to a liquid. The condenser water then carries the heat to the cooling tower where the heat is rejected to atmosphere. This can be as simple as an orifice plate or as complicated as a electronic modulating thermal expansion valve. McQuay Distinction series chillers use a Thermal Expansion Valve to give excellent modulation with a wide range of capacity and temperature conditions. It has the advantage of graphically showing the process, the cooling effect and the work required to make it happen. As the refrigerant changes from a liquid to gas, the pressure (and temperature) stays constant. The heat is being absorbed as a phase change (latent energy). The refrigeration effect is the change in enthalpy from 1 to 2, simply expressed as BTUlb. The work is the change in enthalpy from point 2 to point 3 times the flow of refrigerant. Compressors end up with the work of compression as heat in the refrigerant. Open drive motors reject their winding heat in to the mechanical room. ![]() The vertical aspect of the curve shows the rise in refrigerant pressure (and temperature) from 2 to 3.
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