Judul: Uji Kinerja Pemanfaatan Membran Reverse Osmosis pada Mesin Pendingin Absorpsi LiBr-H20
Abstrak: Absorption refrigeration system LiBr-H2O is an alternative refrigeration system to substitute vapor-compression refrigeration system, which has negative impact to environment and using mechanical energy for its operation. However, the absoption refrigeration system still needs thermal energy to regenerate the refrigerant from its absorber. The purposes of this study is to study the performance of reverse osmosis membrane to regenerate refrigerant H2O from the LiBr-H2O in absorption refrigeration system and to calculate the COP of the system. The experiment was conducted intermittently, where regeneration and refrigeration process occured separately. The study uses 3 level of LiBr-H2O concentration, namely 30%, 25%, and 20% with a variety of pressure treatments. The result of this research shows that COP of the system at concentration of 30% was 0.130 – 0.270, at concentration of 25% was 0.035 – 0.055, and at concentration of 20% was 0.015 – 0.020
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Judul: Exergy Analysis of Membrane Utilization for Solution Separation in LiBr-H2O Absorbtion Refrigeration System
Abstrak: Absorbtion refrigeration system provides prominent advantages in tems of environmental impact and energy consumption. Absorbtion refrigeration system uses natural refrigerant, such as water, which gives no harm to the environment. In terms of energy consumption, it requires heat to regenerate refrigerant from its absorber and provide the refrigeration effect. This form of energy is preferred since heat can be supplied from various sources, including waste heat and renewable energy, and thermodynamically categorized as low quality energy. However, effectiveness of refrigerant regeneration could only be obtained if the temperature is high enough. In this study, the heat utilization in the regeneration process will be eliminated by introducing membranes for separating the refrigerant from the absorber. Specifically, the objectives of this research are to :1) to study the absorbtion mechanism of water vapor by LiBr-H2O solution in a controlled condition, 2) to study the regeneration process of LiBr-H2O using reverse osmosis (RO) membrane and vacuum membrane distillation (VMD) when applied in LiBr-H2O absorbtion refrigeration system, 3) to perform the energy and exergy analysis in LiBr-H2O absorbtion refrigeration system using RO membrane. The membrane was used as a tool to separate the refrigerant from absorbent which performs as regeneration process in conventional absorbtion system. As separation component, RO membrane employs pressure to oppose the osmotic pressure and pass certain component through the pores. While, VMD employs vacuum pressure and thermal, so that the substance to be transported through the membrane is in form of vapor. The result shows that absorbtion rate of water vapor by LiBr-H2O solution was influenced by solution concentration, temperature, humidity and pressure. The highest absorbtion rate was 0.031 g/minute which was occurred at temperature 40°C, RH 70% and solution concentration 60%. Prediction model was developed to calculate the absorbtion parameter inspite of P-T-X diagram.The highest water vapor absorbtion in absorber using spiral wound module-based RO membrane occurred at initial concentration of 30%, wich is the highest concentration used in the experiment. Increasing of operation pressure during separation process will increase permeation flux but decrease rejection factor.Unexpectedly, permeate of the RO membrane still contain LiBr at concentration 7w/w %-9w/w%, which affect the achievable cooling temperature and cooling capacity. Optimization of regeneration using VMD was conducted with response surface methodology (RSM) and the result show that highest permeate flux (0.93 kg.m-2.s-1) can be achived at initial concentration of 47.5%, temperature of 80°C and flow rate of 1.9 L.min-1.COP obtained in absorbtion refrigeration system using RO membran with initial concentration 20% was in the range of 1.147-1.171. Exergy analysis shows that increasing pressure of RO membrane at concentration 20% increased the irreversibity.On the other hand, exergy analysis on VMD shows that higher concentration and temperature will increased irreversibility.
Keyword: refrigeration, absorbtion, reverse osmosis, vacuum membrane distillation, energy, exergy

Judul: Bantalan Duduk Monyet Sulawesi
Abstrak: Kepulauan Sulawesi memiliki tingkat endemisitas fauna yang tinggi. Tujuh spesies monyet dari genus Macaca (macaques) adalah contoh fauna endemik tersebut. Mereka mempunyai sepasang bantalan duduk yang disebut ischial callosities. Bantalan duduk ini sangat beragam bentuknya. Selama ini, keragaman bentuk tersebut baru dideskripsikan secara verbal. Namun, ~ndeskripsian secara verbal tidak mampu mencakup keseluruhan variasi bentuk :%,ang ada dan membuat rekonstruksi bentuk menjadi subjektif. Pencakupan variasi ~entuk yang optimal dan rekonstruksi bentuk yang objektif dapat dilakukan ~elalui analisis kuantitatif. Penelitian ini bertujuan untuk menganalisis secara ;'-'uantitatif bentuk dari bantalan duduk monyet~monyet di Sulawesi menggunakan ~ua perangkat morfometrika geometris yaitu Thin-plate Spline dan Generalized ~rocrustes Analysis. Dua spesies lainnya dari genus Macaca yang berada di ~ekitar Sulawesi juga diikutsertakan sebagai pembanding. Hubungan antar bentuk -:clan arah perubahannya dapat ditentukan dari hasil kuantitatif ini. Bantalan duduk ::::I ~onyet Sulawesi mempunyai keragaman yang lebih besar dibandingkan M [ascicu!aris dan M nemestrina. Penyebab utama variasi adalah perbedaan pad a ;ragian dorsal dan pelekukan bantalan duduk. Terdapat tiga tipe bentuk bantalan &tiuduk pada monyet Sulawesi, yaitu oval tanpa pelekukan (M tonkeana dan M ~naurus), oval dengan pelekukan ke luar (M ochreata dan 1111. brunnescens), dan ::Oval atau seperti ginjal dengan pelekukan ke dalam (M hecki, M nigrescens, dan &V: nigra). Penyebaran tipe-tipe tersebut sesuai dengan penyebaran monyet' §nonyet di Sulawesi saat inL Arah perubahan bentuk bantalan duduk bermula dari 'bentuk oval yang dimiliki spesies di daerah tengah dan selatan pulau. Pelekukan ke arah luar berkembang di bagian tenggara pulau, sedangkan pelekukan ke dalam berkembang di bagian utara pulau.
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