Performance Investigation of Cooling Machine Practice Props After Retrofitted by Natural Refrigerants

Penyesuaian komponen utama mesin pendingin perlu dilakukan setelah di-retrofit/diganti dengan refrigeran baru yang ramah lingkungan. Ini dilakukan untuk mendapatkan kinerja mesin pendingin yang baik. Penelitian ini bertujuan untuk menyelidiki pengaruh penyesuaian komponen utama mesin pendingin dalam meningkatkan kinerja mesin pendingin setelah menggunakan refrigeran baru yang ramah lingkungan. Penelitian dirancang secara eksperimen pada mesin pendingin jenis refrigerator yang menggunakan refrigeran R-134a sebagai fluida kerja. Jenis refrigeran hidrokarbon yang digunakan untuk menyubtitusi R-134a adalah Musicool-22 (MC-22). Beban pendinginan dalam kabin evaporator adalah larutan garam. Pengujian dilakukan dalam dua tahap. Pada tahap pertama refrigerator beroperasi dengan kondisi asalnya (R-134a dan CT1/variasi 1) dan pada tahap kedua fluida kerja R-134a di-retrofit dengan MC-22 dengan penyesuaian komponen utamanya. Selanjutnya kinerja refrigerator dianalisis menggunakan software CoolPack 1.5 dengan membandingkan nilai Refrigerating Effect (RE), kalor kerja kompresor, dan angka kinerja (COP) refrigerator sebelum di-retrofit dan setelah di-retrofit. Hasil analisis menunjukkan bahwa angka kinerja refrigerator terbaik adalah saat refrigerator beroperasi dengan variasi 3 (refrigeran MC-22, alat ekspansi CT2) dengan kenaikan nilai COP berkisar 0,62% sampai 2,12% dari kondisi asalnya.

Investigation of Wickless Heat Pipe Performance Filled With R134a

The wickless heat pipe (theroosyphon) is ordinate of three divisions the condenser, evaporator and insulated region (adiabatic region). In this work, the condenser and evaporator regions are made of copper tube with a length of 300 mm, for each an exterior diameter of 28.2 mm and an interior diameter of 26.4 mm. While the insulated region has a length of 400 mm and an exterior diameter of 28.2 mm. The evaporator region of the heat pipe bounded by a coiled heat source that represented the heat source. The condenser is encapsulated in a plastic cylinder to accommodate the flow of the cooling water. Thermosyphon has been filled by R- 134a working fluid. The effect of heat input, filling ratio and sink temperature were all tested and measurement. The results showed that the heat transfer performance increases when the applied energy to the evaporator increases while the total heat transfer efficiency of the heat pipe increases the gradient temperature between the medium of the evaporator and the condenser increases. The optimum fill rate is 119 % (250g), the sink temperature is 20°C, and it has been found to be suitable for optimum heat pipe performance.

Metallic Oxides for Innovative Refrigerant Thermo-Physical Properties: Mathematical Models

Nano-refrigerant is announced to become an excellent refrigerant, which often improves heat transfer efficiency in the cooling systems. Different materials can be applied to be suspended in traditional coolants in the same way as nanoparticles. In this comprehensive research, mathematical modeling was used to investigate the effect of suspended nanoparticles (Al2O3, CuO, SiO2 and ZnO) on 1,1,1,2-Tetrafluoroethane, R-134a. The thermal conductivity, dynamic viscosity, density and specific heat capacity of the nano-refrigerant in an evaporator pipe were investigated. Compared to conventional refrigerants, the maximum increase in thermal conductivity was achieved by Al2O3/R-134a (96.23%) at a volume concentration of 0.04. At the same time, all nano-refrigerant types presented the same viscosity enhancement of(45.89%) at the same conditions. These types of complex thermophysical properties have enhanced the heat transfer tendencies in the pipe. Finally, the nano-refrigerant could be a likely working fluid generally used in the cooling unit to improve high-temperature transfer characteristics and save energy use.