Studi Eksperimen Pengaruh Perubahan Laju Aliran Massa Udara Pendingin Terhadap Performa Kondenser Untuk Sistem Organic Rankine Cycle (Orc) Berkapasitas 1 Kw

I Wayan, Sudiasa (2018) Studi Eksperimen Pengaruh Perubahan Laju Aliran Massa Udara Pendingin Terhadap Performa Kondenser Untuk Sistem Organic Rankine Cycle (Orc) Berkapasitas 1 Kw. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sektor industri menggunakan energi dalam jumlah yang besar. Akibat inefficiency, hampir 20 – 50% energi ini menjadi gas buang. Setiap industri memiliki tipikal gas buang tertentu yang mana gas buang bertemperatur rendah masih belum optimal pemanfaatannya. Sumber panas bertemperatur rendah ini masih berpotensi untuk dikonversikan menjadi energi listrik dengan teknologi Organic Rankine Cycle (ORC). Siklus ORC merupakan pengembangan siklus Rankine sebagai proses pembangkitan listrik yang tidak menggunakan air sebagai fluida kerja melainkan refrigerant, hidrokarbon atau siloxanes. Komponen utama dalam Organic Rankine Cycle diantaranya kondenser, pompa, turbin dan evaporator.
Pada penelitian ini dilakukan simulasi Organic Rankine Cycle dengan menggunakan Software Aspen Plus®. Terdapat 6 jenis fluida kerja yang digunakan dalam simulasi diantaranya R123, R141b dan R245ca, Pentane, R245fa dan HFC-M1 (50%R245fa+50%R365mfc) dengan batasan temperatur outlet evaporator 950C dan temperatur inlet udara pendingin 300C. Simulasi dilakukan dengan memvariasikan tekanan inlet turbin untuk mengetahui hubungannya terhadap daya, kalor input dan effisiensi sistem. Eksperimen dilakukan dengan menggunakan fluida kerja R141b untuk membandingkan hasil simulasi dengan kondisi aktual. Analisis pada eksperimen difokuskan pada kondenser yakni dengan memvariasikan kecepatan udara pendingin kondenser kemudian menganalisis performa kondenser.
Hasil simulasi menunjukkan bahwa pada tingkat tekanan yang sama 5 bar Pentana memiliki kalor output tertinggi 1.621 kW sementara effisiensi tertinggi dimiliki R141b sebesar 8.65%. Refrigerant R245fa dapat mencapai nilai effisiensi yang lebih tinggi yakni 11.382% saat dioperasikan dengan tekanan yang lebih tinggi. Hasil eksperimen menunjukkan koefisien konveksi eksternal tube kondenser semakin tinggi seiring dengan peningkatan laju aliran massa udara dengan nilai tertinggi 70.763 W/m2K pada kecepatan udara 2.2 m/s dan nilai terendah 50.668 W/m2K pada kecepatan udara 1.34 m/s. Koefisien konveksi sisi dalam tube semakin menurun seiring dengan penurunan kualitas uap proses kondensasi dengan nilai rata – rata 3359.46 W/m2K. Performa kondenser dianalisis dengan metode Number of Transfer Unit dan Effectiveness (NTU – ε) dimana nilai effectiveness yang meningkat secara eksponensial terhadap NTU dengan nilai tertinggi sebesar 0.845 dan nilai terendah sebesar 0.7527
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The industrial sector uses enormous amounts of energy. Due to equipment inefficiency, almost 20 - 50% of this energy is released as flue gas. Each industry has a typical exhaust gas in which the low temperature exhaust gas still not optimally utilized. These low-temperature heat sources still have the potential to be converted into electrical energy using Organic Rankine Cycle (ORC) technology. The ORC cycle is the development of the Rankine cycle as an electricity generation process that does not use water as a working fluid but rather a refrigerant, hydrocarbon or siloxanes. The main components in Organic Rankine Cycle include condenser, pump, turbine and evaporator.
In this study, the Organic Rankine Cycle simulation is conducted using Aspen Plus® Software. There are 6 types of working fluid used in the simulation including R123, R141b and R245ca, Pentane, R245fa and HFC-M1 (50% R245fa + 50% R365mfc) with the temperature limit of 950C at evaporator outlet and air coolant inlet temperature is set at 300C. The simulation is performed by varying the inlet pressure of the turbine to determine its relation to power, heat input and system efficiency. After the simulation, an experiment is conducted using R141b as a selected fluid to compare the simulation results with the actual conditions. The experimental analysis focuses on the condenser by varying the air velocity of the condenser and then analyze its performance.
Simulation results show that at the same pressure level of 5 bar, Pentane has the highest power output of 1,621 kW while R141b has the highest efficiency of 8.65%. Refrigerant R245fa can achieve a higher efficiency value of 11.382% when operated with higher pressure. The experimental results show the condenser external heat transfer coefficient getting higher along with the increase of air mass flow rate. The highest value of 70,763 W/m2K at the air velocity of 2.2 m/s and the lowest value is 50.668 W/m2K at 1.34 m/s airspeed. The inner heat transfer coefficient due to condensation decreased with decreasing the vapor quality, with an average value of 3359.46 W/m2K. Condenser performance is analyzed by Number of Transfer Unit and Effectiveness methode (NTU - ε). The value of effectiveness increased exponentially with increasing NTU with the highest value of 0.845 and the lowest value of 0.7527.

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	Organic Rankine Cycle, Aspen Plus, Compact Kondenser, NTU – Effectiveness
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ164 Power plants--Design and construction T Technology > TJ Mechanical engineering and machinery > TJ263 Heat exchangers
Divisions:	Faculty of Vocational > Mechanical Industrial Engineering (D4)
Depositing User:	I Wayan Sudiasa
Date Deposited:	23 Jun 2021 08:12
Last Modified:	23 Jun 2021 08:12
URI:	http://repository.its.ac.id/id/eprint/54630

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