The experimental investigation of subcooling effects on system COP was carried out on a residential air conditioning using R410A as working fluid, with a compressor capacity of about 0.75 kW. In the experiment, the indoor and outdoor temperatures were controlled at 24°C and 32°C. The results showed that the use of condensate water lowers the refrigerant temperature in the condenser outlet by 2.7°C. By lowering the refrigerant temperature, the cooling capacity of the air conditioning can be enhanced. The decrease in of refrigerant temperature results in COP improvement 16.4%. Besides increasing the COP, the condensate water also decreases the discharge compressor temperature by 7.6°C. The decrease in of the discharge compressor temperature resulted in the decrease in power consumption of the air conditioning system by 5.9%.

Most air conditioners utilize vapor compression refrigeration cycle in their operation. In this cycle, the compressor is deployed to circulate the refrigerant from low to high pressures. Lubrication is an important aspect in the compressor to lubricate internal parts. Due to their remarkable properties in the thermo-physical and heat transfer capabilities, nanoparticles have prospect to be applied in the refrigeration and air conditioning system. The reliability and solubility nanoparticle of TiO2 in refrigeration systems have been investigated by several by several researchers. By introducing TiO2 nanoparticle in the lubricant, the friction coefficient and input power of the compressor can be decreased. An air conditioner with cooling capacity of 2.5 kW is utilized in the experiment. Five different concentrations of nanoparticle in the lubricant, viz.: 0.1, 0.2, 0.4, 0.5 and 0.6 gram of TiO2 in one liter of lubricant were mixed using a magnetic stirrer. After 10 days, TiO2 nanoparticles in the lubricant were observed its solubility. Furthermore, based on their solubility, TiO2 nanoparticle with concentration of 0.2 g/L was selected in the experiments. The results show that the air conditioner using R290 with TiO2 nanoparticle in the lubricants works normally and the input power of the air conditioner decreases about 3.1% and the cooling capacity and the COP increase about 5.1% and 8.4%, respectively, compared to the system without nanoparticle in the lubricant.

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Mesin Jenis A/C split adalah mesin pendingin ruangan dengan kapasitas yang relatif kecil sehingga banyak digunakan sebagai alat pendingin ruangan rumah tangga, apartemen atau ruangan kantor. Seringkali ditemui pemasangan outdoor unit yang secara sembarangan dan tidak memperhatikan aspek performansinya, sehingga mesin menjadi kurang dingin, temperatur kondensasi naik, tekanan kerja kompresor meningkat, akibatnya konsumsi daya listrik akan meningkat. Tujuan dari penelitian ini adalah untuk mengkaji bagaimana pengaruhnya terhadap performansi mesin A/C split apabila penempatan outdoor unitnya divariasikan jaraknya terhadap dinding, sehingga dari hasil kajian tersebut akan diperoleh jarak minimum pemasangan outdoor unit terhadap dinding agar dihasilkan performansi mesin A/C split yang optimum. Metoda yang dilakukan adalah dengan memasang sistem A/C split dimana pemasangan outdoor unit dapat digeser-geser jaraknya terhadap dinding, dimulai dari jarak outdoor unit 5 cm terhadap dinding, selanjutnya berturut turut 10 cm, 15 cm,20 cm,25 cm dan 30 cm.  Dari hasil kajian ini menunjukkan performansi yang baik adalah setelah jarak pemasangan outdoor unit terhadap dinding sekitar 20 cm dengan hasil chilling time lebih cepat (40 menit), tekanan discharge menurun (12%), kerja kompresi menurun (18%), efek refrigerasi meningkat (9%) dan nilai COP meningkat 30%. Sehingga dapat dikatakan jarak yang baik untuk pemasangan outdoor unit terhadap dinding adalah minimum 20 cm.

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