PENGARUH TRANSVERSAL PITCH (ST) DAN LONGITUDINAL PITCH (SL) TUBE SUPERHEATER HRSG TERHADAP KARAKTERISTIK PERPINDAHAN PANAS DAN ALIRAN FLUIDA GAS BUANG TURBIN DENGAN METODE NUMERIK ANSYS

THE EFFECT OF TRANSVERSAL PITCH (ST) AND LONGITUDINAL PITCH (SL) OF HRSG SUPERHEATER TUBE ON HEAT TRANSFER CHARACTERISTICS AND EXHAUST GAS FLUID FLOW OF GAS TURBINE USING ANSYS NUMERICAL METHOD

     Pemanfaatan panas gas buang turbin gas melalui Heat Recovery Steam Generator (HRSG) merupakan upaya penting untuk meningkatkan efisiensi pembangkit listrik sekaligus menekan emisi CO2, di mana konfigurasi jarak antar tube pada superheater, baik transversal pitch (ST) maupun longitudinal pitch (SL), sangat memengaruhi perpindahan panas konveksi dan pressure drop aliran gas. Penelitian ini bertujuan menganalisis pengaruh variasi ST dan SL terhadap karakteristik perpindahan panas dan aliran fluida pada superheater HRSG berbasis turbin gas Solar Mars 100 GN untuk menemukan konfigurasi dengan heat transfer terbesar namun pressure drop terkecil, menggunakan simulasi numerik Computational Fluid Dynamics (CFD) berbasis ANSYS Fluent pada sembilan variasi kombinasi ST dan SL, yaitu V1 (100,45 : 98,63 mm), V2 (100,45 : 123,63 mm), V3 (100,45 : 148,63 mm), V4 (125,45 : 98,63 mm), V5 (125,45 : 123,63 mm), V6 (125,45 : 148,63 mm), V7 (150,45 : 98,63 mm), V8 (150,45 : 123,63 mm), dan V9 (150,45 : 148,63 mm). Performa perpindahan panas dievaluasi melalui Nusselt Number (NU), pressure drop direpresentasikan Euler Number (EU), dan kinerja keseluruhan dianalisis menggunakan Performance Evaluation Criterion (PEC). Hasil menunjukkan penurunan ST dan SL meningkatkan Heat Transfer Rate, Heat Transfer Coefficient, dan NU, dengan pengaruh ST lebih dominan. Berdasarkan evaluasi PEC, V1 memperoleh nilai tertinggi 210,75474 dan V9 terendah 169,97855 dengan selisih 40,77619 atau sekitar 23,99%. Meskipun V1 disertai pressure drop relatif tinggi akibat pitch paling rapat, peningkatan koefisien perpindahan panas dan NU yang dihasilkan mampu mengkompensasinya, sehingga V1 dipilih sebagai konfigurasi tube terbaik karena memberikan keseimbangan optimal antara efektivitas perpindahan panas dan pressure drop.

      The utilization of gas turbine exhaust heat through a Heat Recovery Steam Generator (HRSG) is an important effort to improve power plant efficiency while reducing CO2 emissions, in which the tube arrangement of the superheater both transversal pitch (ST) and longitudinal pitch (SL) significantly affects convective heat transfer effectiveness and pressure drop in the gas flow. This study aims to analyze the influence of ST and SL variations on the heat transfer and fluid flow characteristics of a superheater in a Solar Mars 100 GN gas turbine-based HRSG, in order to determine the configuration with the highest heat transfer rate combined with the lowest pressure drop, using numerical simulation with Computational Fluid Dynamics (CFD) based on ANSYS Fluent across nine combinations of ST and SL, namely V1 (100,45 : 98,63 mm), V2 (100,45 : 123.63 mm), V3 (100,45 : 148,63 mm), V4 (125,45 : 98,63 mm), V5 (125,45 : 123,63 mm), V6 (125,45 : 148,63 mm), V7 (150,45 : 98,63 mm), V8 (150,45 : 123,63 mm), and V9 (150,45 : 148,63 mm). Heat transfer performance was evaluated using the Nusselt Number (NU), pressure drop was represented by the Euler Number (EU), and overall performance was analyzed using the Performance Evaluation Criterion (PEC). The results show that decreasing ST and SL increases the Heat Transfer Rate, Heat Transfer Coefficient, and Nu, with ST having a more dominant influence than SL, V1 produced the highest heat transfer performance while V9 produced the lowest, whereas the lowest Eu was obtained at V7. Based on PEC evaluation, V1 achieved the highest value of 210,75474 and V9 the lowest at 169,97855 a difference of 40,77619, or approximately 23,99%. Although V1 exhibits a relatively higher pressure drop due to its tightest pitch spacing, the resulting increase in heat transfer coefficient and NU compensates for this drawback, making V1 the optimal tube configuration due to its balanced heat transfer effectiveness and pressure drop.