Judul: Study of Paddy Dryer Using Basalt Rock As Heat Storage Media From Biomass Combustion
Abstrak: Salah satu upaya untuk meningkatkan pengeringan dengan pembakaran tungku biomassa padat adalah dengan menyimpan panas yang sudah dihasilkan dari pembakaran tersebut kedalam batu basalt. Penelitian penyimpanan panas pada batu basalt ini bertujuan untuk mempelajari karakteristik penyimpanan termal batu basalt yang menggunakan pembakaran biomassa pada berbagai konfigurasi aliran udara, laju pembakaran dan jarak alas tungku serta mengevaluasi kinerja sistem penyimpanan panas pada tungku biomassa untuk pengeringan gabah. Penelitian penyimpanan panas dilakukan dengan dua tahap yaitu charging dan discharging. Pada percobaan jarak alas tungku pembakaran dengan batu basalt 23 cm, untuk suhu outlet 40˚C diperoleh waktu discharging rata – rata sebesar 664 menit dan eifisiensi discharging sebesar 73,5%. Kemudian, untuk outlet suhu 45˚C, diperoleh waktu discharging rata – rata sebesar 452 menit dengan efisiensi discharging rata – rata sebesar 65,75%. Selanjutnya, sistem penyimpanan panas diaplikasikan untuk pengeringan gabah. Pada pengeringan 1, dengan suhu inlet rata – rata 46,13˚C dan kadar air awal gabah 22,82 %bb, dibutuhkan waktu pengeringan 360 menit untuk mencapai kadar air akhir 13,88 %bb dan konsumsi energi spesifik yang diperoleh sebesar 5,45 MJ/kg air yang diuapkan. Pada pengeringan 2, dengan suhu inlet rata – rata 41,41˚C dan kadar air awal 22,73 %bb, dibutuhkan waktu pengeringan 420 menit untuk mencapai kadar air akhir 13,40 %bb dan konsumsi energi spesifik yang diperoleh sebesar 5,31 MJ/kg air yang diuapkan. Kata kunci: Charging, discharging, batu basalt gabah, penyimpanan panas, One of the efforts to improve drying with biomass furnace combustion is to store the heat that has been generated from the combustion into basalt rock. The aims of this research are to studied the characteristics of the basalt rock heat storage system using coconut shells, as solid biofuel, in various configuration of air flow, combustion rate, furnace base distance and evaluate the performance of the application of heat storage system in biomass furnaces for paddy drying. There were two stages of experiments that conducted in this study, namely charging and discharging. In the experiment of the distance between the furnace base with basalt rock of 23 cm, for the outlet temperature of 40˚C, the average discharging time is 664 minutes and the discharging efficiency is 73.5%. Then, for the outlet temperature of 45˚C, the average discharging time is 452 minutes and the average discharging efficiency is 65.75%. Next, a heat storage system was applied for paddy drying. In drying 1, with an average inlet temperature of 46.13 ˚C and the initial moisture content of paddy was 22.82% wb, it takes 360 minutes of drying time to reached the final moisture content of 13.88% wb and specific energy consumption of 5.45 MJ/kg of evaporated water. In drying 2, with an average inlet temperature of 41.41˚C and the initial moisture content of paddy was 22.73% wb it takes 420 minutes of drying time to reached the final moisture content of 13.40% wb and a specific energy consumption of 5.31 MJ/kg of evaporated water. Keywords: Charging, discharging, basalt rock, heat storage, paddy
Keyword: basalt stone, charging, discharging, heat storage, paddy

Judul: Performance Heat Pump Dryer Continuously and Intermittently for Drying Paddy
Abstrak: Pengering mekanis yang dapat digunakan untuk mengeringkan gabah salah satunya adalah pengering heat pump kompresi uap (HPKU). Prinsip utama dari heat pump adalah pemanfaatan panas yang dilepaskan di kondensor sebagai sumber panas untuk alat pengering mekanis. HPKU dapat memanfaatkan input panas lingkungan dan menghasilkan output panas yang lebih besar. Penelitian ini bertujuan untuk mengetahui dan menganalisis kinerja pengering heat pump untuk gabah secara kontinu dan intermittent berdasarkan perbedaan konsumsi energi yang digunakan, perubahan laju pengeringan, dan keseragaman kadar air pada gabah. Penelitian ini terdiri dari dua percobaan yaitu percobaan perubahan kadar air akibat percampuran dan percobaan pengeringan heat pump secara kontinu dan intermittent. Bahan baku yang digunakan yaitu gabah dengan kadar air 33-35% basis basah sebanyak 75 kg untuk setiap perlakuanya dengan kadar air yang dicapai adalah 14%. Hasil yang didapatkan dari pengujian pada suhu lingkungan rata-rata 28.5-28.6°C yaitu suhu plenum 39.8-41.4°C, kadar air akhir gabah 16.35-18.42%bb dengan waktu pengeringan 11.42-13.25 jam, COP heat pump 2.70-3.16, SMERT 2.03-2.42 kg/kWh, dan SMERTotal 1.51-1.80 kg/kWh. Hasil pengujian mesin HPKU dengan dua perlakuan menunjukan bahwa perlakuan intermittent terbukti dapat menyeragamkan kadar air gabah secara keseluruhan dan menurunkan energi daripada perlakuan kontinu., One of the mechanical dryers that can be used to dry grain is the vapor compression heat pump dryer (VCHP). The main principle of the heat pump is the utilization of the heat released in the condenser as a heat source for the mechanical dryer. VCHP can take advantage of environmental heat input and produce higher heat output. This study aims to determine and analyze the performance of a heat pump dryer for continuous and intermittent grain based on differences in energy consumption used, changes in drying rate, and uniformity of moisture content in grain. This study consisted of two experiments, there are experiments on changes in water content due to mixing and experiments on continuous and intermittent heat pump drying. The raw material used is grain with a moisture content of 33-35% on a wet basis as much as 75 kg for each treatment with a moisture content of 14% achieved. The results obtained from testing at an average ambient temperature of 28.5-28.6°C, namely plenum temperature 39.8-41.4°C, final grain moisture content 16.35-18.42%bb with drying time 11.42-13.25 hours, COP heat pump 2.70-3.16, SMERT 2.03-2.42 kg/kWh, and SMERTotal 1.51-1.80 kg/kWh. The results of the HPKU machine test with two treatments showed that intermittent treatment was proven to be able to uniform the overall grain moisture content and reduce energy than continuous treatment.
Keyword: continuous, energy, heat pump, intermittent, paddy

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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