Judul: Alelopati dari jenis pohon Pinus merkusii Jungh. et de Vriese dan Eucalyptus platyphylla F. Muell terhadap semai jenis-jenis tersebut dan jenis kayu kuku (Pericopsis mooniana Thw)
Abstrak: Tujuan dari penelitian ini ialah untuk mempelajari kemungkinan adanya pengaruh alelopati dari jenis tanaman hutan P. merkusii dan E. platyphylla terhadap semai jenis-jenis yang bersangkutan tersebut maupun terhadap jenis kayu kuku (Pericopsis mooniana ). ...
Keyword: Nursery, Eucalyptus platyphylla, Pericopsis mooniana

Judul: Produksi, laju dekomposisi, dan pengaruh alelopati serasah pinus merkusii Jungh et de Vriese dan Acacia mangium Wild di hutan gunung Walat, Sukabumi, Jawa Barat
Abstrak: Tujuan dari penelitian ini adalah untuk mengetahui produksi, laju dekomposisi dan kandungan unsur hara serasah Pinus merkusii dan Acacia mangium, serta ada tidaknya penga ruh alelopati dari ke dua jenis se rasah tersebut terhadap pertumbuhan tanaman jagung (Zea mays L.) dan kacang tanah (Arachis hypogaea L.). Penelitian ini terdiri dari tiga bagian utama, yaitu pengukuran produksi serasah, laju dekomposisi, dan pengamatan pengaruh alelopati. Pengukuran produksi serasah dan laju dekomposisi berl okasi di Hutan Tridharma Gunung Walat d"i bawah tegakan A. mangium dan P. merkusii. Sedangkan peng amatan alelopati dilakuk an di rumah kaca Fakultas Kehutanan IPB, Kampus IPB Darmaga, Begor. se'cara keseluruhan penelitian ini memakan waktu lebih kurang 6 bulan (Desember 1991 sampai dengan Mei 1992). Pengukuran produksi serasah, dilakukan dengan membuat empat buah plot penelitian masing-masing dua buah di bawah tegakan A. mangium dan P. merkusii. Luas setiap plot penelitian adalah 10 m x 10 m dan ditentukan secara purposive sampling. Di setiap plot diletakkan secara teratur 5 buah penampung serasah (trap) berukuran 1 m x 1 m dengan tinggi 0,5 m. ...
Keyword: Production, Decomposition, Zea mays; Alelopati, Acacia mangium, Arachis hypogaea

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