Performance of Oil Separator According to the Depth of the Outlet Tube

Abstract

Recent years have witnessed a growing concern over saving energy because of global warming issues and energy price hikes caused by increased oil prices. The need to improve energy efficiency to reduce energy consumption has been raised. Refrigeration systems are also expected to have their energy efficiency improved. A refrigeration system’s the compressor uses lubricating oil. Lubricating oil, along with refrigerant, circulates in a refrigeration system. During this process, the pressure drop increases, and the heat transfer coefficient decreases. Moreover, insufficient lubricant may incur a decrease in performance and damage to a compressor. Therefore, an oil separator is used to separate the lubricant and return it to the compressor. Since an oil separator causes an additional pressure drop, energy consumption should be decreased by increasing the oil separator’s separation efficiency and decreasing the pressure drop. The recent increase in development of large-scale buildings such as skyscrapers and large supermarkets has also increased the demand for large refrigeration machines. At the same time, refrigeration piping is becoming longer, and refrigerant must circulate up to the highest points. A high-pressure head and long piping configuration inevitably increase the quantity of lubricant left on the pipe wall, which in turn increases the loss of lubricants. The increased length and fall height for lubricants to circulate with refrigerant increase the related energy loss. In order to use a compressor in a high-head long-piping refrigeration system, the separation efficiency of the oil separator must be improved. Doing so will also reduce energy losses. Even with an improved separation efficiency, however, an increased pressure drop means additional energy losses. Thus, an oil separator with high separation efficiency and low pressure drop should be designed. So using the Numerical analysis, designed a new oil separator. A series of numerical simulation has been carried out to study peformance of a cyclone type oil separator, which is designed for the compressor of a refrigeration system. Working fluid is R22, which is a typical refrigerant, and mineral oil droplet is supplied. Depending on the outlet tube length, separation efficiency varies from 98.74 to 99.25%. Considering both of the separation efficiency, outlet tube length of the separator has been designed as 158 mm and oil separator length is 310mm.