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Penulis
 
Penulis
  
== Designing & Calculation of Hydrogen Storage Optimization ==
+
=Pressurized Hydrogen Storage Optimization=
 +
==Pressurized Hydrogen Storage==
 +
:
 +
: Pressurized hydrogen storage involves compressing hydrogen gas and storing it in specially designed tanks or cylinders. These tanks are built to withstand high pressures, typically ranging from a few hundred to several thousand pounds per square inch (psi). Pressurized storage offers advantages such as simplicity, portability, and fast refueling times. However, it also presents challenges related to weight, safety, and limited storage capacity. Tank materials must be robust, and strict testing is necessary to prevent leaks or ruptures. Alternative storage methods like cryogenic storage and hydrogen carriers are being explored to address these limitations and optimize hydrogen storage and utilization.
  
'''Designing and optimizing hydrogen storage systems involves several considerations and calculations. Here are some key aspects to consider:'''
 
  
1. Storage Method: There are different methods for hydrogen storage, including compressed gas, liquid hydrogen, and solid-state storage. Choose the appropriate method based on your requirements, such as storage capacity, transportation needs, and safety considerations.
+
==Factors Involved in Designing and Optimizing a Pressurized Hydrogen Storage==
 +
: [[File: 16859845860772405471272770780537.jpg|450px|thumb|middle| Pressurized hydrogen tank (source: Department of Energy)]]
 +
:
 +
: Designing and optimizing a pressurized hydrogen storage involves several factors and processes to ensure its safety, efficiency, and performance. Here are some key considerations in the design and optimization process:
 +
:
 +
: '''Storage Capacity'''
 +
: The required storage capacity of hydrogen must be determined based on the anticipated demand and usage. Factors such as the desired duration of storage, refill frequency, and system requirements play a role in determining the storage capacity.
 +
:'''Material Selection'''
 +
: The choice of materials for the storage tank is crucial. Factors such as material strength, corrosion resistance, hydrogen compatibility, weight, and cost need to be considered. The selected material should meet safety standards, regulatory requirements, and be suitable for the specific application.
 +
:'''Pressure Requirements'''
 +
: Determining the optimal operating pressure is critical to balance storage capacity, tank weight, and safety. Higher pressures allow for more hydrogen storage within a given volume, but it increases material requirements and safety considerations. The pressure requirements should align with the intended use and regulatory standards.
 +
:'''Safety Considerations'''
 +
: Safety is paramount in hydrogen storage design. Factors such as material integrity, leak prevention, pressure relief mechanisms, and appropriate safety measures need to be incorporated. Standards and guidelines from regulatory bodies, such as the International Organization for Standardization (ISO) and national safety codes, should be followed.
 +
:'''Structural Design'''
 +
: The structural design of the storage tank must ensure its mechanical integrity and resistance to external loads, vibrations, and impacts. Finite element analysis (FEA) and other engineering calculations are performed to determine the optimal tank shape, thickness, reinforcement, and support structures.
 +
:'''Thermal Management'''
 +
: Hydrogen storage systems may require thermal management to control temperature variations. Insulation, cooling, or heating mechanisms are employed to maintain the desired hydrogen temperature range and prevent thermal stresses.
 +
:'''Cost Optimization'''
 +
: Optimization techniques, such as mathematical modeling and numerical methods, can be applied to minimize costs while meeting performance and safety requirements. This includes optimizing material usage, tank size, manufacturing processes, and other relevant parameters.
 +
:'''Regulatory Compliance'''
 +
: Compliance with relevant regulations, standards, and codes is essential in the design and operation of pressurized hydrogen storage. It ensures safety, environmental protection, and compatibility with industry norms.
 +
:'''Hydrogen Purity'''
 +
: The required purity level of hydrogen for the specific application should be considered. Impurities in the hydrogen stream can impact the integrity and performance of the storage system. Depending on the application, purification processes may be needed to remove impurities.
 +
:'''Fill and Discharge Rates'''
 +
: The desired fill and discharge rates of hydrogen affect the design and optimization of the storage system. Factors such as the available infrastructure, operational requirements, and efficiency considerations influence the sizing of valves, piping, and other components.
 +
:'''System Integration'''
 +
: Pressurized hydrogen storage systems are often integrated with other components and subsystems, such as hydrogen production units, fuel cells, or transportation systems. Seamless integration and compatibility with these systems are important to ensure overall system performance.
 +
:'''Environmental Considerations'''
 +
: Environmental factors, including temperature variations, exposure to corrosive substances, and seismic activity, should be taken into account during the design process. Adequate protection and design measures, such as coatings, seismic restraints, and environmental monitoring, may be required.
 +
:'''Manufacturing and Fabrication Methods'''
 +
: The manufacturing and fabrication techniques employed impact the quality, cost, and scalability of the storage system. Selection of appropriate manufacturing methods, such as welding, forming, or composite layup, needs to be aligned with the chosen materials and desired characteristics.
  
2. Storage Capacity: Determine the desired storage capacity for your system. It depends on the application and the amount of hydrogen required. Consider factors like energy demand, peak load requirements, and availability of hydrogen supply.
+
=Final Report of Design and Optimization of Pressurized Hydrogen Storage=
  
3. Pressure and Temperature: For compressed gas storage, determine the desired operating pressure and temperature. Higher pressure allows for more hydrogen storage within a given volume but requires stronger and more expensive storage tanks. The temperature affects the hydrogen's density and behavior.
+
==Requirements==
 +
: The specific requirements are '''1 liter''' of Hydrogen with '''8 bar''' Pressure with a maximum cost of '''Rp 500.000,00'''
  
4. Tank Sizing: Calculate the storage tank size based on the desired storage capacity and the chosen storage method. For compressed gas storage, consider the ideal gas law (PV = nRT), where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.
 
  
5. Safety Factors: Account for safety factors when sizing the storage tanks. Design the tanks to withstand potential pressure fluctuations, temperature changes, and external stresses. Consider safety measures to prevent leaks, fire hazards, and explosions.
+
==Material Selection==
 +
: By carefully considering the materials available for pressurized hydrogen storage, our selection has led us to choose '''AISI 316 austenitic stainless steel'''. This decision is rooted in the unique properties and advantages offered by this particular material. Here are some reasons for considering AISI 316 stainless steel for pressurized hydrogen storage:
 +
:'''1) Corrosion Resistance'''
 +
: Hydrogen can cause embrittlement and corrosion in some materials, leading to reduced structural integrity and potential safety hazards. AISI 316 stainless steel offers superior corrosion resistance, particularly in environments with high levels of hydrogen. This property helps ensure the long-term durability and safety of the storage system.
 +
:'''2) Strength and Pressure Resistance'''
 +
: Pressurized hydrogen storage systems require materials with high strength to withstand the internal pressure. AISI 316 stainless steel possesses good mechanical properties, including high tensile strength and yield strength, allowing it to withstand the required pressure levels while maintaining structural integrity.
 +
:'''3) Compatibility with Hydrogen'''
 +
: AISI 316 stainless steel has demonstrated compatibility with hydrogen gas in various studies and practical applications. It exhibits low permeability to hydrogen, reducing the risk of hydrogen loss and ensuring efficient containment within the storage system.
 +
:'''4) Established Industrial Usage'''
 +
: AISI 316 stainless steel is widely used in various industries, including chemical processing, oil and gas, and marine applications. It has a well-established track record and extensive knowledge base regarding its behavior in different environments, making it a trusted material choice for engineering applications.
  
6. Materials and Construction: Choose appropriate materials for the storage tanks based on the selected storage method and safety requirements. Consider factors like weight, durability, and cost. Common materials include carbon fiber, aluminum, and high-strength steel.
+
==Constraints==
 +
: Pressurized hydrogen storage plays a crucial role in various applications, ranging from energy storage to fuel cell technology. Designing an optimized storage system requires careful consideration of multiple factors to ensure efficiency, safety, and cost-effectiveness. In this context, incorporating three key constraints - geometrical, material strength, and budget constraints - forms the foundation of an effective optimization model.
 +
:'''1) Geometrical Constraint'''
 +
: The geometrical constraint ensures that the design of the storage system meets specific volume requirements. By setting a constraint on the volume or dimensions of the storage tank, you can optimize the geometrical parameters such as radius and height to ensure the tank can accommodate the desired volume of 1 liter (1000 cm^3). This constraint ensures that the storage tank is appropriately sized and fits within the available space.
 +
:'''2) Material Strength Constraint'''
 +
: The material strength constraint focuses on selecting a material that can withstand the high-pressure environment of the hydrogen storage system. Hydrogen is stored under high pressure (8 bar or 800 kPa), and selecting a material with appropriate strength characteristics is crucial for the safety and integrity of the storage system. By incorporating this constraint, you ensure that the selected material, such as AISI 316 austenitic stainless steel, possesses the necessary mechanical properties to withstand the pressure and prevent any material failures or leaks.
 +
:'''3) Budget Constraint'''
 +
: The budget constraint places a limitation on the cost of the pressurized hydrogen storage system. By including this constraint, you ensure that the optimization model considers the cost-effectiveness of the design. The budget constraint helps in selecting cost-efficient materials and optimizing the geometrical parameters to meet the required specifications while staying within the allocated budget of Rp 500.000. This constraint ensures that the final design is financially feasible and aligns with the available resources.
  
7. Efficiency and Losses: Consider the efficiency of the storage system, including losses during compression, cooling, and reformation processes. Minimize energy losses to optimize the overall system efficiency.
 
  
8. Cost Analysis: Perform a cost analysis of the hydrogen storage system, including initial investment, operation, and maintenance costs. Compare different storage methods and tank materials to find an optimal balance between cost, performance, and safety.
+
===Geometrical Constraints===
 +
: The code provided utilizes an optimization algorithm implemented in Python, utilizing the powerful capabilities of the NumPy and SciPy libraries. The objective of the code is to determine the optimal values for the radius and height of the storage tank by minimizing the surface area, while considering the specified volume of hydrogen. The incorporation of NumPy allows for efficient mathematical operations and array manipulation, while SciPy provides advanced optimization techniques and algorithms
  
9. Integration: Ensure proper integration of the storage system with the hydrogen production and utilization processes. Consider factors like refueling time, compatibility with fuel cell systems or other hydrogen-based applications, and transportation logistics.
+
====Base Geometry====
  
10. Environmental Impact: Evaluate the environmental impact of the chosen storage method. Consider factors like carbon footprint, energy consumption, and potential emissions during the hydrogen production, storage, and utilization processes. Aim for sustainable and environmentally friendly solutions.
+
<syntaxhighlight lang="xml">
  
Note that designing and optimizing hydrogen storage systems is a complex task that often requires specialized engineering expertise. It's essential to consult with experts and consider applicable regulations and standards to ensure safe and efficient operation.
+
import numpy as np
 +
from scipy.optimize import minimize
  
 +
# Define the objective function
 +
def objective(x):
 +
    radius, height = x
 +
    surface_area = 2 * np.pi * radius * (radius + height)
 +
    return surface_area
  
'''Designing Steps to Optimize Hydrogen Storage'''
+
# Define the volume constraint function
 +
def volume_constraint(x):
 +
    radius, height = x
 +
    volume = np.pi * radius**2 * height
 +
    return volume - 1000
  
Optimizing hydrogen storage involves several steps and considerations to ensure efficient and safe storage of hydrogen gas. Here are some steps you can follow to optimize hydrogen storage:
+
# Define the optimization problem
 +
x0 = [1.0, 10.0]
 +
bounds = [(0, None), (0, None)]
 +
constraint = {'type': 'eq', 'fun': volume_constraint}
 +
problem = minimize(objective, x0, bounds=bounds, constraints=constraint)
  
1. Determine the storage method: There are different methods for storing hydrogen, including compressed gas, liquid hydrogen, and solid-state storage. Evaluate the requirements and constraints of your specific application to determine the most suitable storage method.
+
# Extract the optimized results
 +
optimized_radius = problem.x[0]
 +
optimized_height = problem.x[1]
 +
optimized_surface_area = problem.fun
  
2. Choose appropriate materials: Select materials that can safely and efficiently store hydrogen. This includes considering factors such as the material's compatibility with hydrogen, its ability to store high volumes of hydrogen, and any potential safety risks associated with the material.
+
# Print the optimized results
 +
print("Optimization Results:")
 +
print(f"Radius: {optimized_radius:.2f} cm")
 +
print(f"Height: {optimized_height:.2f} cm")
 +
print(f"Surface Area: {optimized_surface_area:.2f} cm^2")
  
3. Improve storage tank design: If you opt for compressed gas storage, focus on enhancing the design of the storage tanks. Consider factors such as tank size, shape, and material to maximize storage capacity and minimize hydrogen leakage. Ensure that the tanks meet safety standards and can withstand high pressures.
+
</syntaxhighlight>
  
4. Enhance safety measures: Hydrogen is a highly flammable gas, so it is crucial to prioritize safety. Implement safety features such as pressure relief valves, leak detection systems, and fire suppression systems to mitigate potential risks. Regularly inspect and maintain storage systems to ensure their integrity.
+
: Dari hasil pengkodean, dapat disimpulkan bahwa dengan meminimalkan luas permukaan, dimensi optimal untuk tangki silinder dicapai dengan rasio tinggi-jari-jari 2:1. Secara spesifik, tangki tersebut memiliki tinggi 10,84 cm dan radius 5,42 cm. Pengukuran ini menghasilkan luas permukaan 553,58 cm^2, yang merupakan luas terkecil yang mungkin untuk kebutuhan volume dan tekanan tertentu.
  
5. Increase storage density: Explore methods to increase the amount of hydrogen stored per unit volume or weight. This may involve using advanced materials, such as metal hydrides or carbon nanomaterials, that can store hydrogen at higher densities. Research and development in this area are ongoing, so stay updated on the latest advancements.
+
====End Cap Geometry====
 +
: Using a purely cylindrical geometry for the storage tank may pose risks due to stress concentration at the corners. To minimize stress concentration and reduce surface area while maintaining the same volume, it is more efficient to adopt a torispherical end cap shape. This shape can be achieved by adding a fillet with a radius equal to half the tank's radius. The filleting creates a smooth curvature and helps reduce stress concentration. Adjustments in the geometrical parameters are necessary to compensate for the volume reduction caused by the filleting.  
  
6. Develop efficient refueling infrastructure: Optimize the infrastructure for refueling hydrogen. This includes designing efficient filling stations, improving dispensing technologies, and ensuring compatibility between storage systems and refueling equipment. Streamline the refueling process to reduce refueling times and enhance convenience.
+
Dengan menghitung persentase pengurangan luas penampang, kita dapat menerapkannya secara terbalik ke volume yang diperlukan untuk mendapatkan batasan volume baru yang ditingkatkan.
 +
: [[File: Hasil_perhitungan_Geometry_End_Cap.png|500px| Fillet Radius of Tank's End Cap Calculation (source: Personal Analysis)]]
 +
: Hasil perhitungan mengungkapkan bahwa jari-jari fillet yang diperoleh untuk tutup ujung tangki adalah '''2.56443 cm'''
  
7. Implement hydrogen purification systems: To ensure the quality of stored hydrogen, consider integrating purification systems. These systems remove impurities, such as moisture, contaminants, and other gases, which can affect the performance and safety of the storage system.
+
===Material Strength Constraints===
  
8. Explore renewable hydrogen production: Hydrogen produced from renewable energy sources, such as electrolysis powered by solar or wind energy, reduces the environmental impact and enhances the sustainability of hydrogen storage. Incorporate renewable hydrogen production methods to optimize the overall hydrogen supply chain.
+
====Mechanical Properties of AISI 316 Austenitic Stainless Steel====
  
9. Conduct thorough testing and validation: Before deploying hydrogen storage systems at scale, conduct comprehensive testing and validation. This includes evaluating storage efficiency, safety performance, reliability, and durability under various operating conditions. Iteratively refine the storage system based on the test results.
+
:[[File: Mechanical_Properties_316.png|500px|thumb|left| Mechanical Properties of AISI 316 Austenitic Stainless Steel (source: Researchgate.com)]]
 +
: The range of acceptable wall thickness is not arbitrary and should not exceed one-fifth of the vessel radius. According to ASME BPV Code Section VIII D.1, the '''minimum wall thickness should be at least 1/16 in (1.59 mm)''', regardless of corrosion allowance, material, or dimensions.
 +
 
 +
: Based on data obtained from Ferrobend, which provides information on the mechanical properties of AISI 316 stainless steel, we will employ both a conservative and less conservative approach by setting our limit at the yield strength and maximum tensile strength to represent failure.
 +
 
 +
: Dalam perhitungan ini, kita akan melakukan iterasi dari radius minimal 2,9 mm hingga 12 mm dengan inkremen 1 mm di setiap iterasi.'''.
 +
 
 +
====Iteration Process====
 +
 
 +
<syntaxhighlight lang=xml>
 +
 
 +
r = 5.42e-2
 +
p = 800000
 +
t = 2.9e-3
 +
 
 +
while t < 12e-3:
 +
  hoop = (r * p)/(t)
 +
  print('for thickness', t, 'hoop stress =', hoop, "Pa")
 +
  t += 1e-3
 +
  if hoop > 205e9:
 +
    break
 +
 
 +
</syntaxhighlight>
 +
 
 +
: Kode tadi untuk menghitung hoop stress untuk berbagai nilai ketebalan mulai dari 2,9 mm hingga 12 mm, dengan constraint yang menghentikan iterasi jika total hoop stress melebihi yield strength stainless steel AISI 316. Berdasarkan hasil, '''semua nilai ketebalan mulai dari 2,9 mm hingga 12 mm dengan kenaikan 1 mm memenuhi batasan yield strength. Berikut adalah hasil perhitungan dari kode yang menunjukkan bahwa tegangan hoop jauh di bawah yield strength 205 MPa.'''.
 +
 
 +
: [[File: Calculation_of_Material_Strength.png|500px| Calculation of Material Strength (source: Personal Analysis)]]
 +
 
 +
==Budget Constraint==
 +
 
 +
Setelah menemukan parameter geometrik, tahap terakhir dari optimasi ini adalah membandingkannya dengan batas biaya yang tidak boleh melebihi Rp500.000,00. Berdasarkan material yang dipilih sebelumnya yaitu AISI 316, kita harus memilih ketebalan dinding tangki yang sesuai dengan kisaran anggaran. Berikut daftar harga beserta perhitungannya.
 +
 
 +
 
 +
[[File:CostConstraints_Alif.png|850px|center]]
 +
 
 +
Berdasarkan perhitungan ini, dengan mengoptimalkan kendala anggaran, bobot minimum yang masuk akal, namun tetap mempertahankan kekuatan yang masuk akal, dipilih ketebalan 6 mm untuk dinding tangki hidrogen ini.
 +
 
 +
 
 +
==My Conscious Efforts in Numerical Method Learning & It's Application in Hydrogen Storage Optimization==
 +
 
 +
<youtube width="200" height="100">CxJBYW9A-2o</youtube>
 +
 
 +
Zefanya Valeryan Harbangan Hutabarat
 +
 
 +
2106630611
 +
 
 +
Metode Numerik - 02

Latest revision as of 23:11, 12 June 2023

BIODATA

Right


Nama :

Zefanya Valeryan Harbangan Hutabarat

NPM :

2106630611

TTL :

Depok, 31 Januari 2003

Program Studi :

Teknik Mesin


                                                               KATA PENGANTAR

Puji syukur saya panjatkan ke hadirat Tuhan Yang Maha Esa. Atas rahmat dan berkat-Nya, penulis dapat menjalani perkuliahannya di jurusan teknik mesin di Universitas Indonesia.

Tidak lupa penulis mengucapkan rasa terima kasih kepada Bapak Dr. Ir. Ahmad Indra Siswantara selaku dosen untuk mata kuliah metode numerik yang telah membantu penulis dalam mengerjakan laman ini. Penulis juga mengucapkan terima kasih kepada teman-teman serta asisten dosen yang telah memberikan masukan serta pengetahuan dalam pembuatan laman ini.

Laman ini berisikan catatan serta tugas saya selama menjalani mata kuliah mekanika fluida dasar. Bagi para mahasiswa yang mencari sumber pengetahuan tentang mekanika fluida dasar, maka laman ini dapat menjadi salah satu sarana pembelajaran.

Penulis menyadari adanya kekurangan pada laman ini. Oleh karena itu, saran dan kritik senantiasa diharapkan demi perbaikan laman ini. Penulis juga berharap agar laman ini dapat memberikan pengetahuan tentang mekanika fluida dasar kepada orang banyak.



Depok, 25 Mei 2023

Penulis

Pressurized Hydrogen Storage Optimization

Pressurized Hydrogen Storage

Pressurized hydrogen storage involves compressing hydrogen gas and storing it in specially designed tanks or cylinders. These tanks are built to withstand high pressures, typically ranging from a few hundred to several thousand pounds per square inch (psi). Pressurized storage offers advantages such as simplicity, portability, and fast refueling times. However, it also presents challenges related to weight, safety, and limited storage capacity. Tank materials must be robust, and strict testing is necessary to prevent leaks or ruptures. Alternative storage methods like cryogenic storage and hydrogen carriers are being explored to address these limitations and optimize hydrogen storage and utilization.


Factors Involved in Designing and Optimizing a Pressurized Hydrogen Storage

Pressurized hydrogen tank (source: Department of Energy)
Designing and optimizing a pressurized hydrogen storage involves several factors and processes to ensure its safety, efficiency, and performance. Here are some key considerations in the design and optimization process:
Storage Capacity
The required storage capacity of hydrogen must be determined based on the anticipated demand and usage. Factors such as the desired duration of storage, refill frequency, and system requirements play a role in determining the storage capacity.
Material Selection
The choice of materials for the storage tank is crucial. Factors such as material strength, corrosion resistance, hydrogen compatibility, weight, and cost need to be considered. The selected material should meet safety standards, regulatory requirements, and be suitable for the specific application.
Pressure Requirements
Determining the optimal operating pressure is critical to balance storage capacity, tank weight, and safety. Higher pressures allow for more hydrogen storage within a given volume, but it increases material requirements and safety considerations. The pressure requirements should align with the intended use and regulatory standards.
Safety Considerations
Safety is paramount in hydrogen storage design. Factors such as material integrity, leak prevention, pressure relief mechanisms, and appropriate safety measures need to be incorporated. Standards and guidelines from regulatory bodies, such as the International Organization for Standardization (ISO) and national safety codes, should be followed.
Structural Design
The structural design of the storage tank must ensure its mechanical integrity and resistance to external loads, vibrations, and impacts. Finite element analysis (FEA) and other engineering calculations are performed to determine the optimal tank shape, thickness, reinforcement, and support structures.
Thermal Management
Hydrogen storage systems may require thermal management to control temperature variations. Insulation, cooling, or heating mechanisms are employed to maintain the desired hydrogen temperature range and prevent thermal stresses.
Cost Optimization
Optimization techniques, such as mathematical modeling and numerical methods, can be applied to minimize costs while meeting performance and safety requirements. This includes optimizing material usage, tank size, manufacturing processes, and other relevant parameters.
Regulatory Compliance
Compliance with relevant regulations, standards, and codes is essential in the design and operation of pressurized hydrogen storage. It ensures safety, environmental protection, and compatibility with industry norms.
Hydrogen Purity
The required purity level of hydrogen for the specific application should be considered. Impurities in the hydrogen stream can impact the integrity and performance of the storage system. Depending on the application, purification processes may be needed to remove impurities.
Fill and Discharge Rates
The desired fill and discharge rates of hydrogen affect the design and optimization of the storage system. Factors such as the available infrastructure, operational requirements, and efficiency considerations influence the sizing of valves, piping, and other components.
System Integration
Pressurized hydrogen storage systems are often integrated with other components and subsystems, such as hydrogen production units, fuel cells, or transportation systems. Seamless integration and compatibility with these systems are important to ensure overall system performance.
Environmental Considerations
Environmental factors, including temperature variations, exposure to corrosive substances, and seismic activity, should be taken into account during the design process. Adequate protection and design measures, such as coatings, seismic restraints, and environmental monitoring, may be required.
Manufacturing and Fabrication Methods
The manufacturing and fabrication techniques employed impact the quality, cost, and scalability of the storage system. Selection of appropriate manufacturing methods, such as welding, forming, or composite layup, needs to be aligned with the chosen materials and desired characteristics.

Final Report of Design and Optimization of Pressurized Hydrogen Storage

Requirements

The specific requirements are 1 liter of Hydrogen with 8 bar Pressure with a maximum cost of Rp 500.000,00


Material Selection

By carefully considering the materials available for pressurized hydrogen storage, our selection has led us to choose AISI 316 austenitic stainless steel. This decision is rooted in the unique properties and advantages offered by this particular material. Here are some reasons for considering AISI 316 stainless steel for pressurized hydrogen storage:
1) Corrosion Resistance
Hydrogen can cause embrittlement and corrosion in some materials, leading to reduced structural integrity and potential safety hazards. AISI 316 stainless steel offers superior corrosion resistance, particularly in environments with high levels of hydrogen. This property helps ensure the long-term durability and safety of the storage system.
2) Strength and Pressure Resistance
Pressurized hydrogen storage systems require materials with high strength to withstand the internal pressure. AISI 316 stainless steel possesses good mechanical properties, including high tensile strength and yield strength, allowing it to withstand the required pressure levels while maintaining structural integrity.
3) Compatibility with Hydrogen
AISI 316 stainless steel has demonstrated compatibility with hydrogen gas in various studies and practical applications. It exhibits low permeability to hydrogen, reducing the risk of hydrogen loss and ensuring efficient containment within the storage system.
4) Established Industrial Usage
AISI 316 stainless steel is widely used in various industries, including chemical processing, oil and gas, and marine applications. It has a well-established track record and extensive knowledge base regarding its behavior in different environments, making it a trusted material choice for engineering applications.

Constraints

Pressurized hydrogen storage plays a crucial role in various applications, ranging from energy storage to fuel cell technology. Designing an optimized storage system requires careful consideration of multiple factors to ensure efficiency, safety, and cost-effectiveness. In this context, incorporating three key constraints - geometrical, material strength, and budget constraints - forms the foundation of an effective optimization model.
1) Geometrical Constraint
The geometrical constraint ensures that the design of the storage system meets specific volume requirements. By setting a constraint on the volume or dimensions of the storage tank, you can optimize the geometrical parameters such as radius and height to ensure the tank can accommodate the desired volume of 1 liter (1000 cm^3). This constraint ensures that the storage tank is appropriately sized and fits within the available space.
2) Material Strength Constraint
The material strength constraint focuses on selecting a material that can withstand the high-pressure environment of the hydrogen storage system. Hydrogen is stored under high pressure (8 bar or 800 kPa), and selecting a material with appropriate strength characteristics is crucial for the safety and integrity of the storage system. By incorporating this constraint, you ensure that the selected material, such as AISI 316 austenitic stainless steel, possesses the necessary mechanical properties to withstand the pressure and prevent any material failures or leaks.
3) Budget Constraint
The budget constraint places a limitation on the cost of the pressurized hydrogen storage system. By including this constraint, you ensure that the optimization model considers the cost-effectiveness of the design. The budget constraint helps in selecting cost-efficient materials and optimizing the geometrical parameters to meet the required specifications while staying within the allocated budget of Rp 500.000. This constraint ensures that the final design is financially feasible and aligns with the available resources.


Geometrical Constraints

The code provided utilizes an optimization algorithm implemented in Python, utilizing the powerful capabilities of the NumPy and SciPy libraries. The objective of the code is to determine the optimal values for the radius and height of the storage tank by minimizing the surface area, while considering the specified volume of hydrogen. The incorporation of NumPy allows for efficient mathematical operations and array manipulation, while SciPy provides advanced optimization techniques and algorithms

Base Geometry

import numpy as np
from scipy.optimize import minimize

# Define the objective function
def objective(x):
    radius, height = x
    surface_area = 2 * np.pi * radius * (radius + height)
    return surface_area

# Define the volume constraint function
def volume_constraint(x):
    radius, height = x
    volume = np.pi * radius**2 * height
    return volume - 1000

# Define the optimization problem
x0 = [1.0, 10.0]
bounds = [(0, None), (0, None)]
constraint = {'type': 'eq', 'fun': volume_constraint}
problem = minimize(objective, x0, bounds=bounds, constraints=constraint)

# Extract the optimized results
optimized_radius = problem.x[0]
optimized_height = problem.x[1]
optimized_surface_area = problem.fun

# Print the optimized results
print("Optimization Results:")
print(f"Radius: {optimized_radius:.2f} cm")
print(f"Height: {optimized_height:.2f} cm")
print(f"Surface Area: {optimized_surface_area:.2f} cm^2")
Dari hasil pengkodean, dapat disimpulkan bahwa dengan meminimalkan luas permukaan, dimensi optimal untuk tangki silinder dicapai dengan rasio tinggi-jari-jari 2:1. Secara spesifik, tangki tersebut memiliki tinggi 10,84 cm dan radius 5,42 cm. Pengukuran ini menghasilkan luas permukaan 553,58 cm^2, yang merupakan luas terkecil yang mungkin untuk kebutuhan volume dan tekanan tertentu.

End Cap Geometry

Using a purely cylindrical geometry for the storage tank may pose risks due to stress concentration at the corners. To minimize stress concentration and reduce surface area while maintaining the same volume, it is more efficient to adopt a torispherical end cap shape. This shape can be achieved by adding a fillet with a radius equal to half the tank's radius. The filleting creates a smooth curvature and helps reduce stress concentration. Adjustments in the geometrical parameters are necessary to compensate for the volume reduction caused by the filleting.

Dengan menghitung persentase pengurangan luas penampang, kita dapat menerapkannya secara terbalik ke volume yang diperlukan untuk mendapatkan batasan volume baru yang ditingkatkan.

Fillet Radius of Tank's End Cap Calculation (source: Personal Analysis)
Hasil perhitungan mengungkapkan bahwa jari-jari fillet yang diperoleh untuk tutup ujung tangki adalah 2.56443 cm

Material Strength Constraints

Mechanical Properties of AISI 316 Austenitic Stainless Steel

Mechanical Properties of AISI 316 Austenitic Stainless Steel (source: Researchgate.com)
The range of acceptable wall thickness is not arbitrary and should not exceed one-fifth of the vessel radius. According to ASME BPV Code Section VIII D.1, the minimum wall thickness should be at least 1/16 in (1.59 mm), regardless of corrosion allowance, material, or dimensions.
Based on data obtained from Ferrobend, which provides information on the mechanical properties of AISI 316 stainless steel, we will employ both a conservative and less conservative approach by setting our limit at the yield strength and maximum tensile strength to represent failure.
Dalam perhitungan ini, kita akan melakukan iterasi dari radius minimal 2,9 mm hingga 12 mm dengan inkremen 1 mm di setiap iterasi..

Iteration Process

r = 5.42e-2
p = 800000
t = 2.9e-3

while t < 12e-3:
  hoop = (r * p)/(t)
  print('for thickness', t, 'hoop stress =', hoop, "Pa")
  t += 1e-3
  if hoop > 205e9:
    break
Kode tadi untuk menghitung hoop stress untuk berbagai nilai ketebalan mulai dari 2,9 mm hingga 12 mm, dengan constraint yang menghentikan iterasi jika total hoop stress melebihi yield strength stainless steel AISI 316. Berdasarkan hasil, semua nilai ketebalan mulai dari 2,9 mm hingga 12 mm dengan kenaikan 1 mm memenuhi batasan yield strength. Berikut adalah hasil perhitungan dari kode yang menunjukkan bahwa tegangan hoop jauh di bawah yield strength 205 MPa..
Calculation of Material Strength (source: Personal Analysis)

Budget Constraint

Setelah menemukan parameter geometrik, tahap terakhir dari optimasi ini adalah membandingkannya dengan batas biaya yang tidak boleh melebihi Rp500.000,00. Berdasarkan material yang dipilih sebelumnya yaitu AISI 316, kita harus memilih ketebalan dinding tangki yang sesuai dengan kisaran anggaran. Berikut daftar harga beserta perhitungannya.


CostConstraints Alif.png

Berdasarkan perhitungan ini, dengan mengoptimalkan kendala anggaran, bobot minimum yang masuk akal, namun tetap mempertahankan kekuatan yang masuk akal, dipilih ketebalan 6 mm untuk dinding tangki hidrogen ini.


My Conscious Efforts in Numerical Method Learning & It's Application in Hydrogen Storage Optimization

Zefanya Valeryan Harbangan Hutabarat

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Metode Numerik - 02