ARTICLES YOU MAY BE INTERESTED INEffect of ambient temperature on the performance characteristics of automotive air conditioning system using R1234yf Abstract.A performance analysis based on exergetic performance coefficient (EPC) criterion was carried out for a dualevaporator vapor compression refrigeration system. The influence of the condensing and evaporating temperature on the EPC, the coefficient of performance (COP), the second law efficiency and the destruction of exergy will be presented. It is found that the evaporating and condensing temperatures have strong effects on EPC in the system. Condensing temperature increases will decrease EPC, COP, and second law efficiency, while evaporating temperature increases will increase the EPC, COP, and second law efficiency. The EPC increases and the total exergy destruction decreases with decreasing temperature difference between the evaporator and refrigerated space and between the condenser and ambient temperature. The EPC can be used for selection of optimal design parameters and the procedures given in this paper for exergy analysis of a dual evaporator vapor compression refrigeration systems has been applied to actual systems.

Abstrak Pohon Marungga merupakan salah satu tumbuhan yang memiliki manfaat yang besar. Untuk daunnya sendiri dapat dijakdikan menjadi suplemen gizi dan juga sebagai bahan dasar kosmetik. Daun Marungga sendiri dapat dijadikan bubuk untuk selanjutnya diproses ke dalam berbagai kebutuhan. Sebelum dijadikan bubuk, sebelumnya daun tersebut harus dikeringkan. Pengeringan manual selama ini membutuhkan waktu yang panjang dan tidak higienis. Pada penelitian ini diperoleh hasil, proses pengeringan selama 19 jam diperolehhasil penurunan kelembaban tidak bisa dilakukan secara cepat. Hal ini disebabkan karena temperatur dalam ruangan tidak mampu memanaskan udara sekitar dengan cepat sehingga proses pengeringan cenderung lebih lambat. Dengan beban pengeringan 20 kg daun Marungga mentah, diperoleh sekitar 3 kg daun kering.Kata kunci: marungga; perpindahan panas; lemari Abstract Marungga tree is one of the plants that have great benefits. The leaves themselves can be transformed into nutritional supplements and also as a cosmetic base ingredient. Marungga leaves themselves can be used as a powder for further processing into various needs. Before being made into powder, the leaf must be dried beforehand. Manual drying so far requires a long time and is not hygienic. In this study the results were obtained, the drying process for19 hours obtained the result of humidity reduction could not be done quickly. This is because the temperature in the room is not able to heat the surrounding air quickly so the drying process tends to be slower. With a drying load of 20 kg of raw Marungga leaves, about 3 kg of dried leaves are obtained.Keywords: marungga; heat transfer; cabinets

The air blast freezer has been used as a freezing method in the fish processing units before being frozen for a long time in cold storage. For this reason, the use of hydrocarbon refrigerants that are more environmental friendly has become a demand and a central issue in the future. This paper presents a performance analysis of using R290 and R600a as a drop-in replacement to R404A and R507A. The system performance analysis is based on the evaporation temperature variation using CYCLE_D-HX software with the condensation temperature maintained constant. The important quantities analyzed are mass flow rate, pressure ratio, temperature discharge, heat released, power consumption, coefficient of performance and refrigeration efficiency. The results show that at minimum evaporation temperature, system performance using R290 and R600a is on average ±14% higher compared to R404A and R507A. R290 has characteristics that are closer to R404A and R507A so it is more suitable to replace the two refrigerants compared to R600a. However, this is a performance analysis that can lead to higher performance than normal conditions.

Siklus Rankine organik telah digunakan sebagai pembangkit listrik yang memanfaatkan sumber kalor bersuhu rendah seperti biomassa, panas bumi, dan limbah kalor dari pembangkit listrik konvensional. Kajian ini dilakukan untuk menganalisis kinerja energi siklus Rankine organik sebagai akibat perubahan suhu kondensasi menggunakan fluida kerja yang lebih ramah lingkungan sebagai pengganti R245FA, yaitu R515A dan R1234ZE. Kinerja sistem didasarkan pada variasi suhu kondensasi menggunakan perangkat lunak Genetron Properties dengan suhu evaporasi dipertahankan konstan. Besaran-besaran penting yang dianalisis adalah laju aliran massa, daya pemompaan, penyerapan kalor, rasio tekanan turbin, dan efisiensi termal. Hasil kajian ini menunjukkan bahwa peningkatan suhu kondensasi sangat berdampak pada meningkatnya konsumsi daya pemompaan tetapi menurunkan rasio tekanan di turbin, dan efisiensi termal sistem. Daya pemompaan yang digunakan untuk menyirkulasikan R515A dan R1234ZE lebih besar dibandingkan dengan untuk menyirkulasikan R245FA, tetapi efisiensi termal sistem ORC yang menggunakan R1234ZE lebih besar dibandingkan R245FA dan R515A.