Evaluation of performance an air conditioning systems using t-junction flash gas refrigerant
The purpose of this study was to determine the performance of air-cooled chiller system using T-junction flash gas bypass refrigerant. The experiment was conducted by installing T-junction after expansion device to separate the phase of refrigerant liquid and gas which flows to the evaporator. The working fluid is used as a cooling medium is R-290. To get performance data, measurements performed at the time of steady state when the water chilling temperature T = 15 C up to T = 10 C and flow rates kept constant at 1 GPM (6.3 x 10-5 m3/s). Finally, the use of T-junction mode in AC system generates an increase in the refrigerating effect and coefficient of performance systems (CoP) by 6% and 17.8 %, respectively. Also, it can decrease the heat of compression by 8.5%. This has implications for the lighter compressor work and saving the power consumption of the AC system.
PENGARUH INJECTION HOT GAS BYPASS REFRIGERAN DI SALURAN SUCTION TERHADAP KINERJA SISTEM AIR COOLED CHILLER YANG MENGGUNAKAN R404A
Tujuan penelitian ini adalah untuk mendapatkan data performa injection hot gas bypass refrigerant pada sistem air cooled chiller yang menggunakan fluida kerja refrigeran R404A. Penelitian ini dilakukan dengan metode eksperimen dengan dua mode pengujian yaitu mode normal dan mode injection hot gas. Kondisi penelitian diatur pada debit air sebesar 0,5 gpm, 1 gpm, dan 1,5 gpm dan perubahan temperatur air yang dimulai dari 15 ° C sampai dengan temperatur 11 ° C. Hasil penelitian menunjukkan bahwa penggunaan refrigeran R404A pada sistem air cooled chiller dengan menggunakan sistem injection hotgas bypass memperoleh hasil yang lebih baik dibandingkan dengan sistem normal. Terjadi peningkatan nilai COP sebesar 20%, sehingga penerapan injection hot gas bypass pada sistem air cooled chiller berpengaruh pada kerja kompresi yang menurun akibat rasio tekanan discharge dan suction lebih kecil.
Intensification of Bubble Disintegration and Dispersion by Mechanical Stirring in Gas Injection Refining
Water model experiments were performed for establishing highly efficient gas injection refining processes. Mechanical stirring was applied to disintegrate the injected bubbles and to disperse them widely in the bath. The bubble disintegration and dispersion were investigated by changing rotation mode (direction of rotation), rotation speed, blade size of the impeller and gas flow rate. Forward rotation of the impeller induced a stable tangential flow and could not disperse bubbles in the bath due to formation of a vortex around the impeller shaft. The tangential flow could be suppressed by forward–interrupt rotation, which could reduce the vortex formation to some degree. However, forward–interrupt rotation could not disperse the bubbles widely in the bath. Forward–reverse rotation could prevent the vortex formation completely and create a strong shear stress field, which intensified the bubble disintegration and dispersion in the bath. Higher impeller rotation speed and larger blade length in forward–reverse rotation could enhance the bubble disintegration and make the dispersed bubbles smaller. The bubble dispersion zone became wider with larger blade length. The bubble size tended to be larger at higher gas flow rates. However, its dependence on the gas flow rate became smaller at higher impeller rotation speed.