This study was conducted to determine the rate of the heat transfer in the radiator. There are two types of hot fluid, namely water and an ethylene glycol-mixed water of 50%. The water entry into the radiator at the temperature of 80°C. The inlet water varied by 0.00000067 m3/s, 0.00013 m3/s, 0.0002 m3/s, and 0.00027 m3/s, and the air release is 1.489 m3/s. The results indicate that the higher the flow of water flowing on the radiator pipe causes a radiator heat transfer rate increase. The best water releases for the radiator test is 0.0002 m3/s. The enhancement of qh increases of 655.26 W or up to 13.06%, qc increases of 402.04 W or 7.57%, Uh increases of 41.3 W/m2K or 11%, Uc increases of 4 W/m2K or 5.67%, and effectivity increases 2.35%.

The earth-air heat exchanger (EAHE) is an air-conditioning device utilizing a heat exchange between the air in the room and the soil. This paper purpose to determine the EAHE performance with experimentally and simulation. The simulation used are transient CFD, turbulent and 3-dimensional. The ambient air was distributed to the pipes with the different velocity of 2 m/s and 3 m/s. It was found that the earth-air heating exchanger effectiveness at air velocity 2 m/s for testing was 0.84 while for theoretical of 0.97. The coefficient of performance (COP) of EAHE increase from 1.341 to 1.761 when the increasing air velocity from 2 m/s to 3 m/s. The COP value also increases from 1.473 to 2.278 at the increasing of air velocity from 2 m/s to 3 m/s. The average of the COP value of the simulation result of the incoming air velocity was 1.99422 for velocity 3 m/s and 1.41426 for the velocity 2 m/s. For the average effectiveness of the simulation result obtained 1.00074 for the velocity of 3 m/s and 0.86100 for velocity 2 m/s.

No abstract

Earth-Air Heat Exchanger (EAHE) is cooling hot air by utilizing cold soil temperatures. This research was conducted to determine the out temperature (Tout) on the pipe for each variation of the inlet temperature (Tin) and variety of the inlet fluid velocity. In this research, the comparison between the experimental results and the results of theoretical calculations. In this study the air velocity of entry was adjusted using blowers and for measurement of temperature in pipes using thermocouples. From the experimental results of out temperature (Tout) at the tube with air velocity of 1 m/s is relatively the same as the result of theoretical calculation, the temperature decrease reaches temperature of ± 25 C, while for out temperature (Tout) experimental result using air velocity of 3 m/s tends to be higher than the exit temperature (Tout) on the theoretical calculation, ie only reaches a temperature drop at a point of ± 26 °C. The decrease in temperature of the underground culverts affects the length of pipe used in the research because the more air passes the pipe surface air, the faster the heat transfer between the air and the pipe wall occurs.

Salah satu komponen sistem pendingin pada mesin pembakaran dalam adalah alat penukar kalor kompak jenis radiator. Performansi suatu radiator berdampak besar terhadap sistem pendinginan mesin. Secara tidak langsung, radiator yang memiliki performansi tinggi akan meningkatkan efisiensi bahan bakar kendaraan melalui pengurangan bobot radiator. Penelitian ini bertujuan untuk menguji performansi radiator secara eksperimental dan perhitungan teoritis. Obyek penelitian ini ialah sebuah alat penukar kalor kompak jenis radiator yang digunakan pada kendaraan berkapasitas mesin 1300 cc. Alat penukar kalor tersebut dipasangkan pada serangkaian alat uji radiator. Hasil penelitian ini menunjukkan kesetimbangan energi yang diperoleh dari hasil eksperimental memiliki penyimpangan maksimum +/- 6 %. Koefisien perpindahan panas maksimum sisi udara dan air ialah 35,3 W/m2.K dan 252,39 W/m2.K. Penyimpangan antara temperatur udara dan air keluar radiator secara teoritis dan eksperimental sebesar rata-rata 8,47 % dan 1,1 %.