Study of ammonia screw compressor used in a refrigeration unit a chiller with economizer

Background: Energy conservation and reduction of negative environmental impact of refrigeration units are relevant when developing new equipment. In this regard, we study the development of an ammonia oil-filled screw compressor for a low-temperature refrigeration cycle with an economizer. Ammonia is a natural refrigerant not subject to the Montreal, Copenhagen, and Kyoto Protocols, and economizers allow to increase the refrigeration coefficient compared to a two-stage cycle.

Aim: To propose a method to calculate intermediate pressure at which a refrigeration cycle with an economizer will have the highest refrigeration coefficient.

Methods: The refrigeration coefficient is calculated analytically. For this purpose, we developed a plant diagram. For all studied modes, we developed cycles s in enthalpy-pressure diagrams and calculated the refrigeration capacity, power consumption, and the refrigeration coefficient.

Results: We determined the correlation of refrigeration coefficient with the intermediate pressure for all studied modes.

Conclusion: We developed a method to calculate intermediate pressure at which a a refrigeration cycle with an economizer has the highest performance.