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Abstrak :
An investigation into flow boiling void fraction was conducted to observe its characteristics and to develop a new correlation of void fraction based on the separated model. The study used a natural refrigerant of R-290, flowed in a horizontal tube of 7.6 mm inner diameter under experimental conditions of 3.7 to 9.6oC saturation temperature, 10 to 25 kW/m2 heat flux, and 185 to 445 kg/m2s mass flux. The void fraction, calculated by the present experimental data, was used for comparison with 31 existing correlations, including model types as follows: homogeneous, slip ratio, K?h correlation, drift flux, and a model based on the Lockhart-Martinelli correlation (Xtt). A new void fraction correlation, as a function of liquid and vapor Reynolds numbers, was proposed, based on the data. The measured pressure drop was compared with some pressure drop correlations that use the newly developed void fraction combination. The best prediction was shown by the homogeneous model.

Abstrak :
Kebutuhan terhadap refrigeran alternatif untuk sistem refrigerasi semakin meningkat. Salah satu refrigerant alternatif yang umum digunakan terutama dalam keperluan sistem tata udara pemukiman adalah propana. Propana atau R290 memiliki keunggulan karena selain mudah didapatkan, juga memiliki sifat properti termodinamika dan perpindahan kalor yang cukup baik antara lain viskositas dinamik serta rapat massa jenis yang kecil dan stabil sehingga memiliki kemampuan penyerapan kalor yang baik meskipun membutuhkan perhatian terutama di dalam penannganan potensi bahaya ledakan. Salah satu metode yang umum digunakan di dalam analisis performa sistem refrigerasi adalah aliran dua fasa. Perhitungan korelasi perhitungan tekanan dilakukan dengan menggunakan basis data yang berasal dari penelitian Pamitran, et. al (2011) yang terdiri dari fluks kalor q = 5-20 kW/m2, G = 50-180 kg/m2. s; temperatur saturasi 0-11 oC, dan fraksi massa atau kualitas uap 0-1. Hasil menunjukkan bahwa fluks laju aliran massa, fluks kalor, dan bilangan Reynolds fasa campuran berbanding lurus terhadap penurunan tekanan aktual, persamaan korelasi Friedel (1979) memberikan nilai yang lebih akurat untuk memprediksi penurunan tekanan dengan nilai MAE (Mean Absolute Error) sebesar 59,12 % dan regim aliran yang terbentuk adalah regim aliran plug (kantong udara), slug, dan transition menuju wavy-annular menurut peta pola aliran Zhuang, et.al (2016). ......The need for alternative refrigerants for refrigeration system is increasing. One of the alternative refrigerants that commonly used, especially in residential air conditioning systems, is propane. Propane or R290 has the advantage because in addition to being easy to obtain, it also has good thermodynamic properties and heat transfer, including small and stable dynamic viscosity and density so that it has good heat absorption ability although it requires attention, especially in potential explosion hazards. One of the methods that commonly used in refrigeration system performance analysis is two-phase flow. Calculation of the correlation of pressure drop is carried out using a database derived from Pamitran, et. al (2011) which consists of parameters range such as heat flux q = 5-20 kW/m2, G = 50-180 kg/m2. S, saturation temperature 0-11 oC, and mass fraction or vapor quality 0-1. The results show that the mass flow rate flux and heat flux are directly proportional to the actual pressure drop with a greater effect of mass flow rate flux and Friedel's (1979) correlation equation provides a more accurate value for predicting pressure drop with MAE (Mean Absolute Error) value of 59,12 %. On the flow pattern map of Zhuang, et.al (2016) a plug-slug and transition flow condition to wavy-annular is formed.

Abstrak :
Berbagai percobaan pressure drop aliran dua fasa pada pipa minichannel telah dilakukan. Selain mendapatkan data eksperimental, banyak peneliti juga membandingkan data eksperimen mereka, bahkan menambahkan data peneliti lain ke korelasi yang ada. Tujuan pada eksperimen ini untuk mengenal karakteristik pressure drop pada aliran dua fasa dengan menggunakan pipa horizontal minichannel dan refrijeran propane (R290), eksperimen ini menggunakan 18 korelasi yang ada dimana terbagi menjadi dua metode untuk mencari nilai pressure drop, yaitu metode separated dan homogeneous. Kondisi eksperimen ini menggunakan pipa horizontal dengan diameter dalam 3 mm, untuk mass flux divariasikan dari 50 hingga 180 kg/m2s, sedangkan untuk heat flux divariasikan 5 hingga 20 kW/m2, temperature saturasi divariasikan 10 hingga 11 oC dan vapor quality 0 hingga 1. Hasil pada eksperimen ini berhasil mendapatkan korelasi terbaik dalam memprediksikan data eksperimen, yaitu korelasi milik Sun dan Mishima (2008) dengan mean absolute error sebesar 27,64 % ......Various experiments on the pressure drop of the two-phase flow boiling in the mini channel tube has been carried out. In addition to obtaining data on experimental pressure drop, many researchers have also compared their experimental data, and even added the data of other researchers to existing correlations. The purpose of this experiment is to identify the characteristics of the pressure drop in a two-phase flow using a horizontal minichannel pipe and a propane refrigerant (R290), this experiment uses 18 existing correlations which are divided into two experiments using a horizontal pipe with an inner diameter of 3 mm, for mass flux. varied from 50 to 180 kg / m2s, while for heat flux it was varied from 5 to 20 kW/m2, saturation temperature was varied from 10 to 11 oC and vapor quality was 0 to 1. This experiment managed to get the best correlation in predicting experimental data,the correlation of Sun and Mishima (2008) with a mean absolute error of 27.64%