Uji karakteristik perpindahan panas pada loop thermosyphon sebagai alat recovery panas temperatur  rendah

Suhendra, Bobie

Abstrak Tujuan dari penelitian ini adalah untuk mempelajari efektivitas Alat penukar kalor loop thermosyphon (APKLT) berfluida kerja refrigerant R134a pada variasi tekanan fluida kerja 0,8 MPa dan 1,2 MPa. Thermosyphon dibuat dari tiga bagian yaitu, evaporator, kondensor dan bagian adiabatik. Evaporator terbuat dari pipa tembaga berdiameter 3/4 inchi dengan panjang 3,5 cm. Kondensor terbuat dari pipa tembaga berdiameter 3/4 inchi dengan panjang 15 cm. Bagian adiabatik jalur uap terbuat dari pipa tembaga berdiameter 3/4 inchi dan panjangnya 25 cm dan jalur cairan (liquid line) berdiameter 3/8 inchi dengan panjang 27 cm. Hal yang diteliti meliputi pengaruh kecepatan aliran udara (fluida yang dipanaskan) sebesar 0,8 m/s, 1 m/s, dan 1,2 m/s terhadap efektivitas APKLT serta pengaruh peningkatan suhu evaporator sebesar 40°C,50°C, dan 60°C terhadap efektivitas APKLT. Penelitian dilakukan secara eksperimen dimana evaporator APKLT diberi pemanas dengan heater. Dari penelitian ini diperoleh hasil bahwa efektivitas perpindahan panas APKLT fluida kerja bertekanan 1,2 MPa sekitar 30-68% dan lebih tinggi dibandingkan efektivitas perpindahan panas APKLT fluida kerja bertekanan 0,8 MPa sekitar 22-35%. Efektivitas menurun seiring peningkatan kecepatan aliran udara. Hambatan termal APKLT bertekanan 0,8 MPa sekitar 0,3-0,45 oC/W dan lebih besar dari hambatan termal APKLT bertekanan 1,2 MPa sekitar 0,08-0,4 oC/W. Kata kunci: loop thermosyphon, Alat penukar kalor, refrigerant R134a, efektivitas, hambatan termal. Abstract The objective of this research was to investigate the effectiveness of loop thermosyphon heat exchanger with working fluid of R134a at pressure variation of working fluid at 0.8 MPa and 1.2 MPa. Thermosyphon consists of three sections, i.e., evaporator, condensor, and adiabatic section. The evaporator was made of copper tubes with a diameter of 3/4 inchi and length of 3.5 cm. The Condensor was made of copper tubes with a diameter of 3/4 inchi and length of 15 cm. The adiabatic section (vapour line) was made of copper tubes with a diameter of 3/4 inchi and length of 25 cm and liquid line was made of copper tubes with a diameter of 3/8 inchi and length of 27 cm. The adiabatic section (liquid line) was made of copper tubes with a diameter of 3/8 inchi and length of 27 cm. The experiments were conducted to investigate the effects of air velocity of 0.8 m/s, 1.0 m/s, and 1.2 m/s whereas the evaporator temperature being varied at 40°C, 50°C, and 60°C to the effectiveness of loop thermosyphon. This research were done experimentally where the evaporator was heated by electric heater. The result showed that the thermsyphon heat transfer effectiveness of 1.2 MPa was about 30-68% and higher than the thermosyphon effectiveness of 0.8 MPa that was about 22-35%. The effectiveness of thermosyphon was slightly decresing when velocity was increasing. The thermal resistance of thermosyphon at 0.8 MPa was about 0.3-0.45C/W and higher than the thermal resistance of thermosyphon at 1.2 MPa that was about 0.08-0.4C/W. Keywords: loop thermosyphon, heat exchanger, refrigerant R134a, effectiveness, thermal resistance