No abstract

More than 50% of power plants in Indonesia are Coal-Fired Steam Power Plants. According to the Ministry of Energy and Mineral Resources of Indonesia, coal reserves in Indonesia will run out in 67 years. Fuel saving can be done by operating the system at the highest efficiency operating conditions. These conditions can be determined by analysing the operating history of the system along with the energetic and exergetic performance produced using machine learning algorithm. Unfortunately, energetic and exergetic performance calculation of the Coal-Fired Steam Power Plants system that is not easy results in lack of system performance target datasets generated from the history of the Coal-Fired Steam Power Plants operation, so that the Steam Powerplant performance data generation software written using the Python programming language is created in this paper to calculate the Coal-Fired Steam Power Plants energetic and exergetic performance using IAPWS IF-97 formulation quickly and accurately. Accuracy of the software written in this paper was tested using the Coal-Fired Steam Power Plants performance values calculated manually as a comparison and result difference between the two types of calculations below 1% and able to cut manual calculation time from 142.46 minutes to 14.34 minutes using the software which is feasible to generate target variable datasets needed for performance prediction using machine learning algorithm.

A flat-plate thermal collector combined with a PV panel also called a PV/T collector is a device that converts solar irradiation into thermal energy and electrical energy simultaneously. The unused thermal energy of the PV/T collector is absorbed by the flat-plate thermal collector. This may then contribute directly to an enhancement of the electrical efficiency of the PV/T collector. In the present study, the effect of geometry and Reynolds Number on the thermal performance of flat-plate thermal collectors is numerically investigated. Thereafter, CFD simulation is then implemented to characterize the thermal performance in terms of absorber temperature and convection heat transfer coefficient. To disturb the fluid flow pattern in this work the 45o inclined fins are attached underneath the surface of the collector model and they act as an absorber. Monthly average weather data of inlet fluid temperature and ambient temperature as well as solar irradiation level implemented in this study were obtained from the Meteorological, Climatological and Geophysical Agency of Bandarlampung regency. Several different cases have been considered by varying the fin height from 20 to 80 mm, fin thickness from 1 to 4 mm, and Reynolds number from 1500 to 6000. The results show that increasing the fin geometry (the fin thickness and fin height) and Reynolds Number reduce the flat-plate surface temperature due to the more conductive and convective heat transfer process. However, in terms of the convective heat transfer coefficient parameter, the Reynolds Number implemented has a dominant effect compared to the fin geometry. Moreover, by increasing Reynolds Number by four times, there is a decrease in the mean surface temperature by 26% and an increase in the mean convective heat transfer coefficient of 146% compared to the initial conditions

Salah satu upaya untuk mengurangi biaya penyediaan energi panas adalah menggunakan energi matahari. Namun, energi matahari sangat bergantung pada cuaca yang sulit dikontrol oleh manusia. Oven menjadi solusi utama dalam industri yang beroperasi secara kontinu.Salah satu perkembangan teknologi oven adalah sistem rotary dryer yang memiliki pengeringan lebih merata. Namun, sistem tersebut masih mengkonsumsi energi panas yang besar. Konsumsi energi yang besar dapat direduksi dengan mengurangi tekanan ruang pengering hingga lebih kecil dari tekanan atmosfer (tekanan vakum) yang berakibat pada penurunan titik didih air. Dengan demikian, kandungan air dalam produk dapat menguap pada temperatur yang lebih rendah. Densitas udara pada kondisi vakum lebih kecil dibanding kondisi atmosfer. Menurunnya densitas udara menyebabkan jumlah energi panas yang dibutuhkan untuk menaikkan temperatur udara lebih sedikit. Investigasi awal karakteristik laju perpindahan panas transien pada rotary dryer bersirip dilakukan dengan studi numerik. Hasil yang diperoleh menunjukkan waktu yang dibutuhkan sebesar 30.33 detik untuk menaikkan temperatur produk dari temperatur lingkungan hingga mendekati temperatur dinding ruang pengering pada tekanan 10 KPa, dan 47,67 detik pada tekanan 50 KPa, selanjutnya 81 detik pada tekanan 1 atmosfer. Dengan demikian, ruang vakum berputar dapat mempercepat waktu pemanasan dan layak dilanjutkan dengan studi eksperimental. One of the efforts to reduce the cost of providing heat energy is to use solar energy. However, solar energy is highly dependent on the weather, which is difficult for humans to control. Ovens are the leading solution in industries that operate continuously. One of the developments in oven technology is the rotary dryer system which has more even drying. However, the system still consumes a large amount of heat energy. Large energy consumption can be reduced by reducing the drying chamber pressure to less than atmospheric pressure (vacuum pressure), resulting in a decrease in the boiling point of water. Thus, the water content in the product can evaporate at lower temperatures. The density of air under vacuum conditions is smaller than atmospheric conditions. The decrease in air density causes the amount of heat energy needed to raise the air temperature less. Numerical studies carried out initial investigations of the transient heat transfer rate characteristics in fin rotary dryers. The results obtained show that the time needed is 30.33 seconds to raise the product temperature from ambient temperature to close to the drying room wall temperature at a pressure of 10 KPa, 47.67 seconds at a pressure of 50 KPa, and 81 seconds at a pressure of 1 atmosphere. Thus, a rotating vacuum chamber can speed up drying time and is worth continuing with experimental studies.