Judul: Pertumbuhan Anakan Kapur Tanduk (Dryobalanops lanceolata Burck.) pada Berbagai Tingkat Penutupan Kanopi di KHDTK Haurbentes, Jasinga
Abstrak: Deforestasi hutan telah berdampak pada produktivitas hutan terutama pada kelompok jenis komersial, seperti jenis Dipterocarpaceae sehingga perlu dilakukan upaya rehabilitasi untuk keberlanjutan produksi. Jenis Dryobalanops lanceolata Burck. merupakan salah satu jenis dari famili Dipterocarpaceae yang pertumbuhannya termasuk cepat yang dapat dijadikan pilihan jenis untuk rehabilitasi. Penelitian ini bertujuan menganalisis persentase penutupan kanopi yang baik untuk pertumbuhan anakan D.lanceolata. Penelitian ini menggunakan hubungan regresi antara diameter dan tinggi tanaman dengan persentase penutupan kanopinya. Persamaan dengan fungsi rasio merupakan model yang dapat menjelaskan hubungan paling baik antara pertumbuhan anakan D.lanceolata dengan penutupan kanopinya. Adanya penutupan kanopi sebesar 31% - 37 % mampu memberikan pertumbuhan tinggi antara 70.6-75.5 cm untuk anakan D.lanceolata dan penutupan kanopi sebesar 29% - 31% mampu memberikan pertumbuhan diameter antara 11.6-11.7 mm.
Keyword: deforestasi, Dryobalanops lanceoalata, penutupan kanopi, pertumbuhan, rehabilitasi

Judul: Pertumbuhan Kapur Tanduk (Dryobalanops lanceolata Burck.) pada Tingkat Keterbukaan Kanopi dan Pemupukan yang Berbeda
Abstrak: Upaya rehabilitasi lahan kritis dalam kawasan hutan maupun areal bekas penebangan merupakan kegiatan yang penting untuk dilakukan. Jenis Dipterocarpaceae merupakan kelompok jenis yang potensial untuk dikembangkan dalam pemulihan areal hutan terdegradasi, salah satunya adalah kapur tanduk (Dryobalanops lanceolata Burck.). Tujuan penelitian ini adalah mengetahui pengaruh faktor keterbukaan kanopi, dosis pupuk kandang, dan kondisi fisik lingkungan (suhu, kelembaban, kelerengan, dan kondisi tanah) terhadap pertumbuhan Kapur Tanduk (D. lanceolata.) di KHDTK Haurbentes, Jawa Barat. Hasil penelitian menunjukkan perlakuan perbedaan tingkat keterbukaan kanopi (71.34 %, 37.91%) dan dosis pupuk kandang (0, 2, 4 kg/lubang tanam) tidak memberikan pengaruh nyata baik secara tunggal maupun interaksi keduanya terhadap pertambahan diameter dan tinggi anakan D. lanceolata. Perbedaan tingkat keterbukaan areal menghasilkan respon yang berbeda pada masa awal pertumbuhan, tingkat keterbukaan 71.24% (areal terbuka) memiliki respon pertumbuhan yang baik terhadap diameter sedangkan pada tingkat keterbukaan 37.91% (dibawah naungan) pertumbuhan tinggi tanaman. Dengan demikian, sampai umur 6 bulan anakan D. lanceolata dapat beradaptasi dengan tingkat keterbukaan kanopi antara 37 – 72%. Kondisi lingkungan pada petak penelitian di KHDTK Haurbentes sesuai dengan karakteristik tempat tumbuh jenis tersebut sehingga mampu mendukung pertumbuhan anakan D. lanceolata.
Keyword: Dryobalanops lanceolata, keterbukaan kanopi, pertumbuhan, pupuk kandang

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