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Abstrak :
The enhancement of heat transfer performance in heat exchanger is achieved by reducing the size of the hydraulic diameter or by using a working fluid that has a better thermal conductivity compared to conventional working fluids. The application of a small hydraulic diameter can be found in the microchannel heat exchanger (MCHE). The design and the testing of the MCHE were done in this research. The MCHE was tested with several working fluids, such as the distilled water, the Al2O3-water nanofluids at 1%, 3% and 5% volume concentration, and the SnO2-water nanofluids at 1% volume concentration. The temperature of inlet and outlet were set at 50o C and 25o C, respectively. The variations of flow rate at the inlet were applied from 100 ml/min up to 300 ml/min. The addition of nanoparticle in the base fluid was proven to improve the heat transfer of the MCHE, the 5% Al2O3-water and 1% SnO2-water nanofluids are able to absorb the heat 9% and 12% higher than the base fluid. The overall heat transfer coefficient of MCHE with 5% Al2O3-water and 1% SnO2-water nanofluids were 13% and 14% higher than the base fluid.

Abstrak :
Experimentation on and implementation of phase-change materials for thermal storage is attracting increasing attention by those seeking a potential resolution to energy issues. This study investigates beeswax as a high thermal-capacity phase-change material with the objective of analyzing the thermal properties and behaviors of beeswax/CuO nano-PCM. The study uses differential scanning calorimetry apparatus to measure the melting temperature and thermal capacity of nano-PCMs. The study found nano-PCM melting temperatures of 63.62°C, 63.59°C, 63.66°C, 63.19°C, and 62.45°C at 0.05, 0.1, 0.15, 0.2, and 0.25 wt%, respectively. FTIR testing found no chemical reaction between CuO and beeswax. The existence of CuO nanoparticles enhanced thermal conductivity of beeswax but reduced its heat capacity. However, the change in latent heat caused no significant effects in the performance of beeswax/CuO. Thus, the results showed that heat transfer of composite beeswax/CuO melts faster than base phase-change material