Ayudya Arindari Murahardjo

Introduction

Halo!

Perkenalkan, nama saya Ayudya Arindari Murahardjo, akrab disapa Arin. Saya merupakan mahasiswa semester 4 Program Studi Teknik Perkapalan Universitas Indonesia.

Resume Pertemuan 1 (26/5/2023)

Pada pertemuan pertama mata kuliah Metode Numerik, saya belajar mengenai pemahaman tentang "cosciousness", yakni semua orang harus memiliki kesadaran dalam melakukan segala sesuatu termasuk mempelajari Metode Numerik. Terdapat study case pada pertemuan pertama, yaitu mahasiswa diminta untuk menyelesaikan persamaan (x-1)^2/x-1 jika x=1. Pada hal ini, tidak terdapat jawaban yang mutlak atau eksak (1 solusi) karena pada hakikatnya di dalam dunia ini tidak terdapat suatu hal yang pasti.

Semakin kita dewasa, kita semakin kian mengerti akan arti hidup ini, begitu juga dengan kepercayaan yang selama ini kita anut. Mungkin sebagian besar orang memiliki pemahaman yang mereka yakini itu benar dan tidak ada salahnya memilih jalan hidup masing-masing selagi kita tetap "conscious"

Design & Optimization of Pressurized Hydrogen Storage

Design & optimization of pressurized hydrogen storage with maximum cost Rp 500.000,-

Capacity

Volume : 1 liter

Pressure : 8 bar

WEEK 1 PROGRESS

Designing and optimizing a pressurized hydrogen storage system with a 1-liter capacity and 8-bar pressure within a budget of Rp 500.000,- involves careful consideration of materials, dimensions, and cost optimization. Here's a design and optimization approach:

Material Selection

To meet the budget constraint, consider using high-density polyethylene (HDPE) as the material for the storage system. HDPE is cost-effective and offers good chemical resistance.

Container Design

Shape: Design a cylindrical container, as it is a common and practical shape for pressurized storage. Dimensions: Determine the container dimensions based on the desired volume and pressure. The container's volume is fixed at 1 liter, and the pressure is 8 bar.

Wall Thickness: Calculate the required wall thickness using the Barlow's formula: t = (P * D) / (2 * S), where P is the pressure (8 bar), D is the diameter of the container, and S is the allowable stress for HDPE. Ensure the calculated wall thickness is within the manufacturing capabilities and budget constraints.

Optimization Strategies

Material Cost: Compare prices from different HDPE suppliers to select the most cost-effective option. Manufacturing Process: Consider extrusion or injection molding processes for HDPE container fabrication, as they can be cost-effective for producing cylindrical shapes.

Size Optimization: Optimize the dimensions of the container to minimize material usage and manufacturing costs while still meeting the required volume and pressure specifications. This can be achieved by adjusting the diameter and height of the container.

Safety Considerations: Incorporate safety features into the design, such as pressure relief devices and adherence to safety standards and regulations for hydrogen storage.

Final Result Design & Optimization of Pressurized Hydrogen Storage

Fundamental Steps

To calculate the design of an optimal hydrogen storage tube with a 1-liter volume and 8-bar pressure specification, we can follow these steps:

1. Determine the desired dimensions: Since the volume and pressure specifications are given, the next step is to calculate the dimensions of the storage tube.

2. Convert the volume to cubic meters: 1 liter is equal to 0.001 cubic meters.

3. Convert the pressure to pascals: 1 bar is equal to 100,000 pascals.

4. Apply the ideal gas law: The ideal gas law equation, PV = nRT, can be used to calculate the volume of the storage tube. However, we need additional information such as the number of moles of hydrogen (n) and the temperature (T) to proceed with the calculation. Without this information, we cannot determine the exact dimensions of the storage tube.

5. Consider the material and safety factors: Once you have the necessary dimensions, you will need to select a suitable material that can withstand the pressure and store hydrogen safely. Materials such as high-strength steel or composite materials may be considered.

Material Safety Factors

AISI 304L stainless steel, which is a low-carbon variant of AISI 304, generally exhibits good compatibility with hydrogen in a variety of conditions. Here are some key points regarding the compatibility of AISI 304L with hydrogen:

1. Strength and Pressure

The material strength and pressure ratings of AISI 304L stainless steel should be considered to ensure the tank can safely withstand the pressure generated by the hydrogen gas. The design should take into account factors such as the tensile strength, yield strength, and the specific design codes or standards that provide guidelines for pressure vessel design.

2.Fatigue Resistance

Hydrogen storage tanks may experience cyclic loading, such as during filling, emptying, or transportation. AISI 304L stainless steel generally exhibits good fatigue resistance. However, proper design considerations should be taken to account for cyclic loading, including the application of appropriate fatigue safety factors and consideration of potential stress concentrations.

3. Corrosion Resistance

AISI 304L stainless steel offers excellent corrosion resistance in various environments, including hydrogen gas. It provides resistance to general corrosion and pitting corrosion, which is beneficial for hydrogen-related applications. However, in certain aggressive conditions, such as high-temperature hydrogen environments or hydrogen containing high levels of sulfur compounds, precautions should be taken as it may increase the risk of hydrogen embrittlement or other forms of corrosion.

4. Hydrogen Permeation

Similar to other stainless steels, AISI 304L has relatively low permeability to hydrogen. While it can restrict the flow of hydrogen, it is still important to consider the potential for hydrogen permeation over time. Proper design considerations, including material thickness, welding techniques, and surface treatments, should be implemented to minimize the risk of hydrogen permeation in critical applications.

5. Temperature Considerations

AISI 304L stainless steel retains its corrosion resistance and mechanical properties at both low and high temperatures. However, at elevated temperatures above 300-400°C, sensitization can occur, potentially reducing its corrosion resistance. In hydrogen environments, high-temperature exposure may increase the susceptibility to hydrogen-assisted cracking or embrittlement. Therefore, operating conditions, including temperature, should be carefully considered when utilizing AISI 304L in hydrogen-related applications.

6. Weld Integrity

Hydrogen storage tanks are typically fabricated by welding. It is important to ensure proper welding techniques and procedures are followed to maintain the integrity of the welded joints. Adequate welding qualifications, inspections, and non-destructive testing can help ensure the quality of the welds and minimize the risk of defects or failure.

The Calculation

from scipy.optimize import minimize

 # Fungsi tujuan yang ingin kita maksimalkan
   def objective(x):
   return -x[0]  # Maksimalkan volume hydrogen

 # Batasan tekanan
   def pressure_constraint(x):
   volume = x[0]
   pressure = x[1]
   return pressure - 8  # Tekanan harus sama dengan atau kurang dari 8 bar

 # Batasan volume
   def volume_constraint(x):
   volume = x[0]
   pressure = x[1]
   return volume - 1  # Volume harus sama dengan atau kurang dari 1 liter

 # Batasan batas harga
   def cost_constraint(x):
   volume = x[0]
   pressure = x[1]
   cost = 200000 + 500000 * (volume - 1) + 300000 * (pressure - 8)
   return 500000 - cost  # Total biaya harus kurang dari atau sama dengan Rp 500.000,-

 # Initial guess
 x0 = [0.5, 6]  # [Volume, Tekanan]

 # Batasan
 constraints = [{'type': 'ineq', 'fun': pressure_constraint},
              {'type': 'ineq', 'fun': volume_constraint},
              {'type': 'ineq', 'fun': cost_constraint}]

 # Optimisasi
 result = minimize(objective, x0, constraints=constraints)

 # Print hasil optimisasi
 print("Status:", result.success)
 print("Volume Optimal (liter):", result.x[0])
 print("Tekanan Optimal (bar):", result.x[1])