ANALISA PENGARUH JARAK NOSEL DENGAN CONSTANT AREA SECTION PADA PERFORMANSI STEAM EJECTOR MENGGUNAKAN CFD

Abstract

Steam ejector refrigeration is refrigeration system utilize waste heat from combustion engine, power plants, and industrial processes to generate the useful refrigeration. Steam ejector is used to replace the mechanical compressor as refrigerant pumping for circulation in the refrigeration system. Steam ejector refrigeration is using lower-grade power for pumping refrigerant, but COP (Coefficient Of Performance) is low. The steam ejector performance directly affects the refrigerating system performance, the performance of steam ejector can be represented by entrainment ratio defined by ratio of suction mass flow rate to motive mass flow rate. Entrainment ratio value increase will be the refrigeration system COP value increases, because of that an investigation on characteristic and an efficient design of ejector are important to improve ejector refrigeration system performance. In this study, the Computational Fluid Dynamics (CFD) is used to predict the flow phenomena and steam ejector performance. Simulation was done by modifying the nosel distance with constant-area section of steam ejector and by varying the operation condition such as pressure and temperature of motive (boiler) and suction (evaporator). The nosel distance with constant-area (throat) section of steam ejector was varied from 0.1 to 5 times the constant-area section diameter. The temperatur of motive was varied at 85oC, 95oC, dan 115oC while temperature of suction was varied at 27oC, 32oC, dan 35oC. The results of simulation show optimum performance get in nosel distance between 1.5 to 4 times constant-area section diameter. The bigger nosel throat the entrainment ratio`s value will decrease. The higher temperature of motive the entrainment ratio`s value will decrease while the higher temperature of suction the entrainment ratio`s value will increase.