Design and Construction of Mini Single Turbine PLTU Demonstration Equipment: As a Thermodynamics Learning Media

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Design and Construction of Mini Single Turbine PLTU Demonstration Equipment: As a Thermodynamics Learning Media

Arwizet. K¹, Desmarita Leni², Remon Lapisa³, Yuda Perdana Kusuma⁴, Pinto Anugrah⁵

1,3Department of Mechanical Engineering, Faculty of Engineering, Universitas Negeri Padang

2Mechanical Engineering, Faculty of Engineering, Universitas Muhammadiyah Sumatera Barat

4Agricultural and Biosystem Engineering, Faculty of Agricultural and Biosystem Engineering, Universitas Andalas.

5Electrical Engineering and Computer Sciences, University of Queensland, Australia Corresponding Author. Email:

1[email protected]

2[email protected] Abstract

Thermodynamics is often considered difficult for students to grasp because it involves abstract concepts that are challenging to visualize without visual aids or physical demonstrations. This research involves the design of a mini power plant trainer as a teaching tool to visualize basic thermodynamics concepts, such as heat transfer, conversion of heat energy into mechanical energy, phase change from steam to liquid, and thermal efficiency. The trainer is designed according to the requirements of the system provided by the thermodynamics lecturer at the State University of Padang, taking into consideration the teaching material and safety aspects. The power plant trainer consists of four main components, including a boiler with a 15- liter water capacity equipped with an automatic sensor stove that can shut off when it reaches 4 bars of pressure and restarts when it drops below 4 bars, a single propeller turbine, a 12-volt generator, and a vertical condenser with coolant flow in the same direction as the steam flow. The testing results of the trainer yielded a boiler efficiency of 46%, thermal efficiency of 21%, with the steam power generated by the boiler at approximately 1734 Watts, condenser power at 1478 Watts, cooling power to convert wet steam into liquid at 119 Watts, and turbine power at 375 Watts. The maximum electrical power reached 2.94 Watts with a voltage of 12 volts and a current of 0.21 amperes. It took 31 minutes to heat 15 liters of water in the boiler to steam with a temperature of 146°C and a pressure of 58 Psi. The trainer can be operated (can rotate the generator) for 4 minutes until the steam pressure drops to 20 Psi. Based on the testing results, the trainer can be operated smoothly and is capable of illustrating difficult thermodynamics concepts that are hard to visualize. Therefore, in an effort to enhance the quality of learning, this trainer can be used as a simulation tool for thermodynamics education.

Keywords: Thermodynamics,Interactive Learning, PLTU, Steam Turbine

How to cite this article :

K. Arwizet, Leni D., Lapisa R., Kusuma Y.P., Anugrah P. (2024). Design and Construction of Mini Single Turbine PLTU Demonstration Equipment: As a Thermodynamics Learning Media . IJIS Edu : Indonesian Journal of Integrated Science Education, 6(1), 22-33. doi: https://dx.doi.org/10.29300/ijisedu.v6i1.13801

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http://ejournal.iainbengkulu.ac.id/index.php/ijisedu 23 INTRODUCTION

Thermodynamics is a branch of physics that studies the transfer of energy. The main concepts in thermodynamics involve changes in energy within a system, alterations in temperature, pressure, volume, and how the system interacts with its surrounding environment (Turns & Pauley, 2020). This field describes energy changes in various forms, such as heat and mechanical work, and how these changes affect the physical and chemical properties of a system (Honig, 2021).

Thermodynamics is a mandatory course for mechanical engineering students as it serves as the fundamental foundation in the development of the field of mechanical engineering. A solid understanding of thermodynamics enables students to optimize processes such as steam power generation (PLTU), engine cooling, and the design of renewable energy systems.

However, based on field observations at Padang State University and previous research, it has been found that thermodynamics is often considered one of the complex and challenging subjects for many students (Atarés et al., 2021;

De Hemptinne et al., 2022)

This is attributed to difficulties in grasping abstract concepts such as entropy and enthalpy, the use of complex mathematical equations, and the lack of tangible visualizations. As a result, students often have to rely on mathematical representations that can be difficult to comprehend. Therefore, there is a need for more interactive learning methods and effective learning media to apply thermodynamic concepts.

Interactive learning media is a form of media designed to facilitate the learning process by actively involving interaction between learners and the media itself. The aim of this media is to enhance engagement and understanding among learners through the use of interactive elements such as buttons, animations, simulations, and other activities that enable active participation in the learning process(Kustyarini et al., 2020;

Liliana et al., 2020). Interactive learning media is not necessarily limited to digital platforms or high-end technology but can encompass various types of tools or devices that enable direct interaction and learner participation (Rahim et al., 2022). Interactive learning media is often customizable to the learner's level of ability or individual needs. This allows for more personalized learning experiences that align with

the characteristics of each individual (Mulders et al., 2020).

Interactive learning in thermodynamics allows students to actively engage in the learning process, rather than passively receiving information. According to (Sudarsana et al., 2019), achieving interactive learning goals requires the use of media that enhance students' abilities in the learning process. Another study by (Damarwan & Khairudin, 2017) states that learning media can stimulate students' feelings, thoughts, interests, and desires, leading to effective and efficient learning processes. The use of teaching aids in thermodynamics and fluid mechanics can help students illustrate complex concepts in thermodynamics and fluid mechanics, thereby improving their understanding. Research results indicate that students are able to remember, understand, and apply these concepts for an extended period after completing such learning.

Trainers can present thermodynamic concepts visually and interactively, allowing students to gain a deeper understanding through hands-on experience. Through active engagement with trainers, students can visualize thermodynamic principles more clearly and reinforce their understanding. This not only enhances student engagement but also enables them to develop problem-solving skills and apply theory in practical situations. One example of interactive learning media in thermodynamics is the Mini Steam Power Plant (PLTU) Trainer.

This instructional tool can be used to illustrate and explain the fundamental principles of thermodynamics involved in the operation of mini steam power plants. By using the Mini PLTU trainer, students can directly observe how the heat energy from fuel combustion is transformed into mechanical energy used to generate electricity, such as the Rankine cycle, phase change of water into steam, heat transfer, and other thermodynamic concepts relevant to steam power generation (Nissenson et al., 2017).

Based on the issues outlined above and field observations, it has been identified that the thermodynamics course includes the study of the steam turbine process. Therefore, an effort to enhance the quality of thermodynamics education at Padang State University has led to the development of a Mini Steam Power Plant (PLTU) single turbine propeller trainer as a thermodynamics learning tool. Consequently, the use of this trainer as a learning medium not only facilitates interactive learning but also engages

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24 http://ejournal.iainbengkulu.ac.id/index.php/ijisedu students holistically in the understanding of

thermodynamics. With this approach, it is hoped that students will not only acquire theoretical knowledge but also be able to apply these concepts in real-world contexts. The trainer is designed with considerations for ease of transport and mobility, the ability to apply thermodynamic concepts related to steam power generation using a propeller turbine, and ensuring the safety of operation and maintenance to prevent damage, accidents, or any potential harm to users.

METHOD

This research falls under the category of Research and Development (R&D), a researh approach aimed at creating, developing, and evaluating new products, systems, or innovations.

This approach is focused on designing solutions to problems or creating superior products (Yaghmaei & Poel, 2021). In the fields of education and instructional technology, design and development research is often applied to create more effective learning materials, devices, or teaching methods (Santos, 2021). In this study, the Mini Steam Power Plant (PLTU) single turbine propeller trainer is designed with considerations for the actual characteristics of steam power plants. The research involves several stages, as illustrated in Figure 1.

Figure 1. Research Method Literature Review

Literature review is the initial stage in the research process aimed at identifying relevant scientific sources related to the research topic.

The focus of the literature review includes basic thermodynamics concepts, thermodynamic laws, and their applications in the context of a steam power plant (PLTU). This study will assist in building a strong understanding of the relevant thermodynamic principles for the research.

System Needs Analysis

The next stage in designing the mini single propeller steam power plant (PLTU) trainer is the system needs analysis. This step aims to determine the specifications and criteria that the trainer being designed must meet. The analysis is conducted through field observations and interviews with professors who teach thermodynamics courses, ensuring that the designed trainer meets user expectations, provides an effective learning experience, and meets the required safety and quality standards.

Design

This trainer consists of four main components: a boiler, a turbine, a generator, and a condenser. The proposed operational principle of the mini single propeller steam power plant (PLTU) trainer can be seen in Figure 2. Each component serves a specific function within the system and reflects basic thermodynamic concepts. For instance, the boiler acts as a heater that transforms water into high-energy hot steam (Camaraza-Medina et al., 2021) The single propeller turbine functions as a converter of thermal energy into mechanical energy, driving the generator. The generator generates electricity from the mechanical energy of the turbine. The condenser acts as a coolant, converting hot steam back into liquid water (Oyedepo et al., 2020).

With this trainer, students can learn concrete thermodynamic concepts in the context of a PLTU, including heat transfer, energy conversion, phase changes, and electromagnetism.

Literature Review

1 2

^Analysis^System^Needs

4

^Design

4

^Trainer^Testing

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http://ejournal.iainbengkulu.ac.id/index.php/ijisedu 25 Figure 2. Mini Single Propeller Steam Power Plant (PLTU) Scheme, where T stands for temperature, P

for pressure, F for flow rate, orange represents gas, red represents steam, and blue represents water Trainer Testing

After the design phase is completed, the next step involves calculations for trainer testing.

The calculations performed are as follows:

a. Steam Power Calculation

Steam power is the power required by the boiler to produce steam with a specific enthalpy.

Steam power can be calculated using equation 1 (Dincer & Al-Muslim, 2001a).

𝑃_𝑠𝑡 = 𝑚_𝑠𝑡. (ℎ𝑏" − ℎ𝑏′) (1)

Where Pst represents steam power, mst is the mass flow rate of steam, hb" is the saturated steam enthalpy at the steam boiler temperature, and hb' is the enthalpy of wet steam at the steam boiler temperature.

b. Boiler Efficiency Calculation

Boiler efficiency is the ratio of the steam power produced by the boiler to the heat required by the boiler to produce steam with a specific enthalpy. Boiler efficiency can be calculated using equation 2 (Shah & Adhyaru, 2011)

𝜇𝑏 = _𝑃^𝑃^𝑠𝑡

𝑔𝑎𝑠 (2) Where Pgas is the power required by the boiler to produce steam with a specific enthalpy, and ηb is the boiler efficiency.

c. Turbine Power Calculation

Turbine power is the power generated by the propeller turbine driven by steam. Turbine power can be calculated using equation 3 (Dincer

& Al-Muslim, 2001b)

𝑃𝑇 = 𝑃𝑠𝑡 – (𝑃𝑐𝑤− 𝑃_𝑐𝑝) (3) Where PT is the turbine power, Pcw is the condenser power, and Pcp is the cooling power.

d. Condenser Power Calculation

Condenser power is the power required by the cooling water to cool the steam into water.

Condenser power can be calculated using equation 4.

𝑃𝑐𝑤 = 𝑉𝑐𝑤. 𝜌_𝑐𝑤.𝐶𝑝. (𝑇_𝑜𝑢𝑡− 𝑇_𝑖𝑛) (4) Where Vcw is the mass flow rate of cooling water, ρcw is the density of cooling water, Cp is the specific heat capacity of cooling water, Tout is the outlet temperature of cooling water from the condenser, and Tin is the inlet temperature of cooling water into the condenser.

e. Thermal Efficiency

Thermal efficiency is the ratio of the technical power generated by the propeller turbine to the steam power required by the boiler to produce steam with a specific enthalpy. This

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26 http://ejournal.iainbengkulu.ac.id/index.php/ijisedu thermal efficiency can be calculated using

equation 5.

𝜇𝑡ℎ = _𝑃^𝑃^𝑡

𝑠𝑡 (5) Where Pt is the turbine power, and Pst is the steam power generated by the boiler that enters the turbine.

RESULT AND DISCUSSION 1. System Needs Analysis

Based on the system needs analysis through field observations and interviews with thermodynamics instructors at Padang State University, technical specifications and features required for the mini steam power plant (PLTU) trainer were obtained. These specifications include concepts of heat transfer, conversion of heat energy into mechanical energy, phase change from steam to liquid, and thermal efficiency. The results of this field observation align with previous research (Bishop, 2017; Pielichowska &

Pielichowski, 2014), which states that thermodynamics is a branch of science that studies heat transfer, energy, and phase changes within closed systems. Fundamental concepts such as internal energy, enthalpy, and entropy serve as essential foundations in understanding how energy is managed and transferred within a PLTU system. The system needs analysis results were then implemented into the design of the mini PLTU trainer, as shown in Figure 3.

Figure 3. Mini Steam Power Plant (PLTU) Trainer Design for Thermodynamics Learning 2. Design

Once the technical specifications from the system needs analysis were obtained, the next step was to design the mini single propeller steam

power plant (PLTU) trainer to meet those requirements. The design of the main components of the mini PLTU trainer is as follows:

a. Boiler

The boiler used in this PLTU trainer has a diameter of 20 cm and a capacity of 15 liters of water with a maximum pressure of up to 5 bars.

This boiler is equipped with automatic steam discharge and an automatic stove that can ignite and turn off by itself, ensuring safe usage for learning purposes. Heat-resistant hoses with a diameter of 6 mm are used for the steam flow from the boiler to the turbine inlet. The boiler design can be seen in Figure 4.

Figure 4. Boiler Design b. Turbine

The single propeller turbine functions as a component that converts thermal energy into mechanical energy in the form of rotation. This turbine operates based on the principle of the conservation of momentum, where the fluid entering the turbine undergoes a change in direction and velocity, resulting in a force that drives the turbine to rotate. This turbine has an outer diameter of 10 cm with 32 blades and a transmission gearwheel of 6 cm, while the gearwheel used in the generator is 3.6 cm. The diameter of the turbine's inlet, where steam enters, is 0.6 cm, while the outlet, where steam exits the turbine, has a larger diameter of 1.2 cm,

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http://ejournal.iainbengkulu.ac.id/index.php/ijisedu 27 as shown in Figure 5. The smaller diameter of the

turbine's inlet compared to the outlet is due to the expansion of steam as it passes through the turbine (Arwizet K et al., 2023) . Expansion is the process in which steam undergoes a decrease in pressure and an increase in volume (Zhang et al., 2021). Therefore, the larger outlet diameter of the turbine can accommodate the larger steam volume and reduce friction as steam exits the turbine.

Figure 5. Turbine Design c. Condenser

In this design, a vertical condenser is used as a device to convert steam into condensate. The vertical condenser has a tubular shape with a diameter of 15 cm. Steam enters the condenser through an inlet with a diameter of 1.2 cm and exits as condensate through an outlet with a diameter of 1 cm. To cool the steam, cooling water is circulated through a spiral pipe with a diameter of 1 cm. The spiral pipe has a circular shape with a diameter of 14.2 cm and is placed inside the condenser tube. The flow direction of the cooling water is parallel to the direction of steam flow, which is from top to bottom, as can be seen in Figure 6.

Figure 6. Condenser Design 1. Trainer Testing

After the design process is completed, the next step is to conduct testing on the trainer that has been created, as shown in Figure 7. To support safety aspects in operating this mini steam power plant (PLTU), an automatic stove is used, which can turn off when the pressure in the boiler reaches 4 bars and can ignite again when the boiler pressure drops below 4 bars. Trainer testing is performed on all components of the mini PLTU, including the boiler, turbine, condenser, and the electricity generated by the generator.

Figure 7. Mini Single Propeller Steam Power Plant Trainer

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28 http://ejournal.iainbengkulu.ac.id/index.php/ijisedu The generator used in this trainer is a 12-

volt Direct Current (DC) voltage generator, capable of producing a voltage of up to 22 volts without a load. Testing using a 3-watt light bulb load, the trainer is capable of producing 2.94 watts of electricity at 12 volts and 0.21 amperes.

Testing is conducted by heating water in the boiler until it becomes steam with a pressure of 4 bars or approximately 58 psi, with steam temperature reaching 146°C. The time required to reach 4 bars of pressure is approximately 31 minutes. The turbine can rotate for 4 minutes until the pressure reaches 20 psi, and below 20

psi, it cannot turn the generator. Figure 8 illustrates the relationship between steam pressure, turbine and generator RPM when a 3- watt light bulb load is applied. Meanwhile, Table 1 displays the measurement results of pressure, turbine RPM, generator RPM, temperature, voltage, and current. Based on Figure 8 and Table 2, it can be observed that higher steam pressure leads to higher turbine and generator RPM. The generator's RPM is higher than the turbine RPM because the generator has a gearwheel diameter of 3.6 cm, which is smaller than the turbine's diameter of 6 cm.

Figure 8. Pressure vs. RPM Comparison

Table 1. Results of Mini Steam Power Plant (PLTU) Trainer Testing

The measured variables in this testing can be seen in Table 2. Data was collected using measuring instruments such as a tachometer, watt meter, flow meter, and type K thermocouple heat

sensors, each of which was placed on the boiler,

turbine inlet, turbine outlet, condenser, and condenser cooling water.

Pressure (Psi) Temperature

(°C) Turbine

RPM Generator RPM Voltage

(Volts) Amperage (Amperes)

58 146 1248 1837 12 0.21

50 143 1076 1606 10 0.16

45 141 904 1436 8 0.12

40 137 762 1173 7 0.08

35 134 484 836 6 -

30 129 342 562 5 -

25 127 215 359 3.7 -

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http://ejournal.iainbengkulu.ac.id/index.php/ijisedu 29 Table 2. Variables Measured During Testing

Variabel Symbol Unit Value

Time ∆𝑡 min 31

Boiler steam pressure

p1 bar 4

Ambient temperature

T1 C 26

feed water temperature

T2 C 25

boiler steam temperature

T3 C 146

inlet turbine temperature

T4 C 114

outlet turbine temperature

T5 C 101

condensate temperature

T6 C 65

cooling water inlet

temperature

T7 C 25

colling water outlet

temperature

T8 C 44

colling water flow rate

Vcw L/h 67

Gas mass 𝑚_𝑔𝑎𝑠 Kg/s

8.13𝑋10⁻⁵𝐾𝑔 amount of 𝑠

condensation

Vc 𝑐𝑚³ 1547

generator electric voltage

U V 14

generator electric current

I A 0.21

Based on Table 2, the boiler efficiency can be calculated using equation 1. However, to determine the boiler efficiency, it is necessary to calculate the power supplied by the gas and the steam power generated by the boiler. To calculate the power supplied by the gas, it can be computed using the following equation.

1. Power supplied

𝑃_𝑔𝑎𝑠= 𝑚_𝑔𝑎𝑠. 𝐻_𝑢

𝑃_𝑔𝑎𝑠= 8.13𝑋10⁻⁵𝐾𝑔

𝑠 . 46354 𝐾𝑗 𝑘𝑔

𝑃_𝑔𝑎𝑠 = 3768 𝑊𝑎𝑡𝑡

Thus, the power supplied by the gas to the boiler is determined to be 3768 Watts. The next step is to calculate the steam power using equation 2. To calculate the steam power, it is necessary to first calculate the mass flow rate of steam using the following equation.

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30 http://ejournal.iainbengkulu.ac.id/index.php/ijisedu 2. The mass flow rate of steam

𝑚_𝑠𝑡 = 𝜌_𝑐.𝑉𝑐

∆𝑡 𝑚_𝑠𝑡 = 1000^𝑘𝑔

𝑚³ . 31 𝑚𝑖𝑛.1000000 𝑚^1547𝑐𝑚³^.1𝑚³^{.1𝑚𝑖𝑛}³.60𝑠

𝑚_𝑠𝑡 = 8.16 X 10⁻⁴𝑘𝑔

⁄𝑠

Thus, the mass flow rate of steam in the boiler is determined to be 8.16 x 10^-4 kg/s. Next, it is necessary to calculate the enthalpy of saturated water and the enthalpy of saturated steam at the saturated steam temperature exiting the boiler, which is 146.1°C. The enthalpy of saturated water and saturated steam is the energy per unit mass contained in liquid water and steam at a specific temperature and pressure, and it can be calculated using linear interpolation techniques because the obtained saturated steam temperature does not match the values in the steam tables.

ℎ = 610.75 𝑘𝐽

𝑘𝑔+ (632.32 − 610)𝑘𝐽

𝑘𝑔 .146.1 ℃ − 145 ℃ 150 ℃ − 145 ℃ h3’ = 615.50 ^𝑘𝐽_𝑘𝑔

ℎ3" = 2740.2 𝑘𝐽

𝑘𝑔+ (2746.4 − 2740)𝑘𝐽

𝑘𝑔 .146.1 ℃ − 145 ℃ 150 ℃ − 145 ℃ h3”= 2741.67 _𝑘𝑔^𝑘𝐽

As a result, the enthalpy of wet steam is determined to be 615.50 kJ/kg, and the enthalpy of saturated steam is 2741.67 kJ/kg. Therefore, the steam power can be calculated using equation 1 as follows:

3. Boiler Steam Power

𝑃_𝑠𝑡= 𝑚_𝑠𝑡. (ℎ𝑏" − ℎ𝑏′) 𝑃_𝑠𝑡 = 8.13𝑋10⁻⁵𝐾𝑔

𝑠 . (2741

− 615.50)𝑘𝐽 𝑘𝑔 𝑃_𝑠𝑡 = 1734 𝑊𝑎𝑡𝑡

Hence, it is known that the steam power generated by the 15-liter capacity boiler over 31 minutes is 1734 Watts. The boiler efficiency can be calculated using equation 2 as follows:

4. Boiler Efficiency

𝜇𝑏 = _𝑃^𝑃^𝑠𝑡

𝑔𝑎𝑠

𝜇𝑏 = ^{1734 𝑊𝑎𝑡𝑡}_{3768 𝑊𝑎𝑡𝑡}. 100 𝜇b = 46 %

It is known that the efficiency of the mini steam power plant (PLTU) trainer boiler is 46%.

5. Condenser Power

Next, the testing of condenser power and cooling power of the condenser is carried out.

Condenser power is the power required to convert wet steam exiting the turbine back into liquid water using cooling water (Zhu et al., 2021).

Meanwhile, cooling power is the power required to lower the saturated steam temperature exiting the boiler to the temperature of wet steam entering the turbine (Jamil et al., 2021). In this mini PLTU condenser, water is used as the cooling fluid at a volume of 67 liters per hour, so the condenser power can be calculated as follows:

𝑃𝑐𝑤 = 𝑉𝑐𝑤. 𝜌𝑐𝑤.𝐶𝑝. (𝑇8− 𝑇7) 𝑃_𝑐𝑤

= 67 𝐿

ℎ . 1ℎ. 1𝑚³

3600𝑠. 1000𝐿 . 1000𝑘𝑔

𝑚³ . 4.18 𝑘𝐽

𝑘𝑔. 𝐾. (317

− 298)𝐾

𝑃_𝑐𝑤 = 1478 𝑊𝑎𝑡𝑡

Therefore, it is known that the condenser power in converting wet steam into liquid is approximately 1478 Watts.

Next, cooling power calculations are performed, where to calculate the pure condensation power, it is necessary to subtract the cooling power for 100 ℃ from the cooling power for condensate (65 ℃). Thus, the cooling power can be calculated as follows:

6. Colling power

𝑃_𝑐𝑝= 𝑚_𝑠𝑡. 𝐶_𝑝. (100 ℃ − 𝑇₆) 𝑃_𝑐𝑝= 8.13𝑋10^{−5 𝐾𝑔}

𝑠 . 4.18 _{𝑘𝑔.𝐾}^𝑘𝐽 . (100℃ - 65℃)

𝑃_𝑐𝑝= 119 𝑊𝑎𝑡𝑡

Therefore, the power for cooling wet steam at 100 ℃ is obtained to be 119 Watts.

After knowing the steam power generated by the boiler, condenser power, and cooling power, the turbine power can be calculated based on the difference between the steam power entering the turbine from the boiler and the steam power exiting the turbine, which is the condenser and cooling power. Thus, the turbine power can be calculated as follows:

7. Turbine Power

𝑷_𝑻= 𝑃_𝑠𝑡 – (𝑃_𝑐𝑤− 𝑃_𝑐𝑝)

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http://ejournal.iainbengkulu.ac.id/index.php/ijisedu 31 𝑷_𝑻= 1734 𝑊𝑎𝑡𝑡−(1478 watt – 119

watt) 𝑷_𝑻= 375 𝑤𝑎𝑡𝑡

And, the power of the mini PLTU trainer turbine is 375 Watts, indicating that the turbine generates mechanical energy of 375 watts from the steam energy entering the turbine. Next, the thermal efficiency of the steam turbine can be calculated using equation 3.

8. Thermal Efficiency

𝜇𝑡ℎ = _𝑃^𝑃^𝑡

𝑠𝑡

𝜇𝑡ℎ = _{1734 𝑤𝑎𝑡𝑡}^{375 𝑊𝑎𝑡𝑡} . 100 𝜇𝑡ℎ = 21 %

Next, the thermal efficiency of this steam turbine is 21%, indicating that the turbine is capable of converting steam power into mechanical power at a rate of 21% of the steam power entering the turbine. This result is not far from the research (Soares & Oliveira, 2017) that obtained a thermal efficiency of 13.3% from a mini power plant using biomass and solar panels as water heaters, and in another study (Boljevic &

Noel, 2007), larger-scale power plants achieved thermal efficiencies of around 25% to 50%.

CONCLUSION

Based on the design of the Mini Steam Power Plant (PLTU) single turbine propeller trainer as a learning tool in thermodynamics, it can be concluded that this trainer effectively illustrates the basic concepts of thermodynamics.

For instance, the boiler functions as a heater that transforms water into high-energy steam. The single propeller turbine acts as a converter of thermal energy into mechanical energy, driving the generator. The generator, in turn, produces electricity from the mechanical energy of the turbine. The condenser serves as a cooler, converting hot steam back into liquid water. This mini PLTU trainer is designed to meet the analytical system needs identified through field observations with the thermodynamics lecturer, ensuring alignment with user requirements such as safety aspects and ease of transport between locations. The trainer also features temperature sensors at various points, including the boiler, turbine inlet, turbine outlet, condenser inlet, condenser outlet, cooling water inlet, and cooling

water outlet. Additionally, the trainer includes an automatic burner that can shut off at a certain pressure and restart when steam pressure begins to decrease, ensuring its safety as a thermodynamics learning tool. Based on testing results, it takes 31 minutes to heat water into steam, reaching a pressure of 4 bar or approximately 58 Psi. With a steam pressure of 58 Psi, the turbine and generator can operate for 4 minutes, producing 2.94 Watts of electrical power (12 volts X 0.21 amperes).

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