Environmental Thermal
Engineering
Lecture Note #13
Professor Min Soo KIM
Clean Room
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What is a Clean Room?
Clean Room❑ Definition of a Clean Room
• A controlled environment that has a low level of pollutants - The concentration of airborne particles is controlled
• Other relevant parameters, e.g. temperature, humidity, and pressure, are controlled as necessary
• The introduction, generation, and retention of particles should be minimized inside the room
FIGURE Clean room in Samsung(left) and NASA(right)
http://bit.ly/2IpKx9z https://www.nasa.gov/image-feature/jpl/now-mars-2020-can-phone-home
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What is a Clean Room?
Clean Room❑ Principles of a Clean Room
http://www.wonbangtech.com/
1. Preventing inflow penetration
- Indoor air pressure - Architectural traffic line - Filter
2. Preventing occurrence
- Staff management
- Staff uniform management - Interior construction materials
3. Preventing accumulation
- Indoor air current
- Interior construction materials - Indoor cleaning
4. Fast Removal
- CLEAN ROOM method - Indoor air current
- The number of air changes
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Airborne Particles (Aerosol)
Clean Room❑ Airborne Particles
• Small particles of solid or liquid suspended in air or gas
• In general, they are classified into several types according to their formation mechanism and shape
Ex) Dust, smoke, mist, fog, and etc.
Dust: Grain-like particles produced during mechanical/physical processes Smoke: Particles mainly generated during the combustion process
• Typically, their size is in the range of 0.002~100 μm
FIGURE Airborne particle sizeshttps://www.qld.gov.au/environment/pollution/monitoring/air/air-pollution/pollutants/particles
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Cleanliness Classification
Clean Room❑ Methods for Ventilation
• Mechanical / Forced
• Natural / Passive
❑ Cleanliness Classification
• Cleanrooms are classified according to the number and size of particles permitted per volume of air
• Among several standards, these two are generally used
• FS 209E: Denote the number of particles of 0.5 μm or larger per cubic foot of air, from Federal Standard
• ISO 14644-1: Specify the decimal logarithm of the number of particles of 0.1 μm or larger per cubic meter of air, from International Standards
Organization
TABLE Cleanliness Classification
https://www.cleanairtechnology.com/cleanroom-classifications-class.php
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Classification by Industry
Clean Room❑ Clean Room Classification by Industry
• Clean rooms are largely classified into industrial clean room (ICR) and biological clean room (BCR), according to the subject of air conditioning
• ICR focuses on the fine particles such as dust
• BCR focuses on the biological particles
• The required cleanliness varies depending on depending on the industry area
FIGURE Comparison of ICR and BCR
https://www.hankyung.com/economy/article/2018080796641 http://hutec.kr/
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Industrial Clean Room (ICR)
Clean Room❑ Industrial Clean Room (ICR)
• Industrial clean rooms are used for various purposes including production and research in many fields such as semiconductor, precision equipment, food packaging, special printing, etc.
• Its main purpose is removing dust in the air
FIGURE Cleanliness by area for ICR
http://korea-es.co.kr/
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Biological Clean Room (BCR)
Clean Room❑ Biological Clean Room (BCR)
• It is used to control/manage contamination and particles of GMP (Good Manufacturing Practice), particles in the air and in microorganisms(germs, viruses) in various fields.
http://korea-es.co.kr/
FIGURE Cleanliness by area for BCR
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Classification by Airflow Direction
Clean Room❑ Non Unidirectional Airflow Clean Room
• The non-unidirectional (turbulent) flow dilutes and discharges the pollutants generated indoors
FIGURE Clean room classification by airflow direction
https://www.mecart-cleanrooms.com/learning-center/what-is-a-cleanroom/
❑ Unidirectional Airflow Clean Room
• It should maintain a straight airflow and ensure that the airflow pattern is as little disturbed as possible at the heart of the
process.
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Non Unidirectional Airflow Type
Clean Room❑ Process
• It receives clean filtered air through high efficiency air filters (HEPA Filter or ULPA Filter) in the ceiling
• The fresh air is mixed with the room air including airborne contamination generated by people and machinery
• The mixed air is removed through an air extracts positioned at the bottom of the wall
FIGURE Non unidirectional airflow clean room
http://1cs.co.kr/business-area/clean-room/icr/
❑ Characteristics
• Simple structure, low cost, and easy to expand the room
• Possibility of recirculation of the particles
• Cleanliness classifications up to ISO 6 can be achieved
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Unidirectional Airflow Type
Clean Room❑ Vertical Type
• It forms an airflow in a single vertical direction by installing an ultra-high- performance filter (HEPA Filter or ULPA Filter) on the ceiling and using the floor as the air extract
• Airborne particulates generated in the indoor space are directly sucked into the floor and do not affect the surroundings
• It can achieve cleanliness of ISO 1~4
• Mainly used as an industrial clean room
❑ Unidirectional Airflow Clean Room
• Unidirectional airflow clean room is more expensive and use much more air than non-directional airflow clean room
• It is classified into vertical type and horizontal type
FIGURE Vertical type clean room
http://1cs.co.kr/business-area/clean-room/icr/
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Unidirectional Airflow Type
Clean Room❑ Horizontal Type
• It makes the air current flow from one side of the wall to the other side of the wall
• An ultra-high-performance filter (HEPA Filter or ULPA Filter) is installed on one side of the inner wall and the opposite side is used as an air extract
FIGURE Horizontal type clean room
• High cleanliness can be maintained on the upstream side (higher than ISO 5), while the cleanliness decreases as it goes downstream (approximately ISO 6)
• Mainly used as a
biological clean room
http://1cs.co.kr/business-area/clean-room/icr/
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Clean Room Equipment
Clean Room❑ Clean Room Equipment
• Generally, several equipment are required such as fan filter unit, lighting, air handling unit, plenum moisturizing system, etc.
FIGURE Clean Room Equipment
https://www.hankyung.com/economy/article/2018080796641
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Clean Room Equipment
Clean Room❑ The Role of the Equipment
• System ceiling:
The part where filters, LED panel lighting, etc. are installed to
maintain cleanliness, temperature and humidity
• Fan filter unit:
Installed on the ceiling and absorbs the particles
• Outdoor air conditioner:
Located outside and introduces clean air into the room
• Plenum moisturizing system:
Control the humidity
• Dry cooling coil:
Handling the internal heat load FIGURE Clean Room Equipment
https://www.itooza.com/common/iview.php?no=2020091418013478012&ss=01
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Clean Room System
Clean Room❑ Clean Tunnel Module (CTM) System
• This is a local circulation method used when the layout is the Bay method
FIGURE CTM system
http://cleanroommirae.com/
• A tunnel module consisted of fan, filter and cooling coil is installed
• Low air circulation power cost
• Slightly inferior performance
• Low flexibility (Difficult to
relocate once CTM is installed)
• Cross-contamination problem
❑ Clean Room Classification by Facilities
• Clean rooms can be classified into various types according to facilities such as air circulation method and layout
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Clean Room System
Clean Room❑ Open Bay System
• Basically, it is a kind of All Down Flow method
• ULPA filter or HEPA filter is placed all over the ceiling and clean air is circulated using a large fan
• This is widely applied to large-scale semiconductor factories
FIGURE Open bay system
http://cleanroommirae.com/
• Before and after the circulation fan, sound absorption facilities are essential to compensate for noise and vibration, and a dry coil is installed in order to control the internal heat generation
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Clean Room System
Clean Room❑ Fan Filter Unit (FFU) System
• This is an individual type vertical unidirectional flow system using FFU
• It circulates clean air by installing a number of FFUs that is
consisted of a small circulation fan unit and ULPA or HEPA filter on the ceiling
FIGURE FFU system
http://cleanroommirae.com/
• Since there is no separate air conditioner for return air supply (circulation is possible only with FFU), this clean room can be constructed very economically
• Due to the saving the
installation area and economical efficiency, it has been widely
applied
Air Purification
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Indoor Pollutants
Air Purification❑ Sources of indoor pollutants
• Those who live in cities spend up to 90% of their time indoors
• 2-5 times more pollution exists indoors than outdoors
FIGURE Possible places of indoor pollution with potential pollutants
https://eschooltoday.com/learn/indoor-air-pollution/
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Indoor Pollutants – Particulate matter
Air Purification❑ PM10 ex) street dust, abrasion
• Inhalable particles
• Deposit in the extra thoracic/upper trachea-branchial region
FIGURE Classification of particulate matter
Human hair
50-70 ㎛ PM10
< 10 ㎛ PM2.5
< 2.5 ㎛ PM0.1
< 0.1 ㎛
미세먼지 초미세먼지
❑ PM2.5 ex) industrial dust, exhaust
• Fine particles
• Deposit in deeper lung
❑ PM0.1 ex) soot(disel, residential burning), exhaust
• Ultra-fine particles
• Pass into the circulatory system
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Indoor Pollutants – Particulate matter
Air PurificationFIGURE US AQI chart
❑ AQI (Air Quality Index)
• AQI is index used for reporting air quality
• The function used to convert from air pollutant concentration to AQI varies by pollutant
https://www.iqair.com/us/blog/air-quality/what-is-aqi
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Indoor Pollutants – VOC
Air Purification❑ VOC (Volatile Organic Compound)
• Human-made chemicals that are used and produced in the manufacture of paints, pharmaceuticals, and refrigerants
• Concentrations of many VOCs are higher indoors (up to 10 times higher) than outdoors
• VOCs are emitted by a wide array of products such as building materials, furnishings, printers, and cleaning supplies
TABLE Classification of VOCs
Description Abbreviation Boiling point range (℃) Example compounds Very volatile
(gaseous) organic
compounds VVOC <0 to 50-100 propane, butane, methyl
chloride Volatile organic
compounds VOC 50-100 to 240-260 formaldehyde, d-Limonene,
toluene, ethanol Semi volatile
organic
compounds SVOC 240-260 to 380-400 chlordane, plasticizers, fire retardants
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Indoor Pollutants – Virus, Bacteria
Air Purification❑ Virus, Bacteria
• Viruses and bacteria can travel through the air, causing and worsening diseases
• Some viruses and bacteria thrive and circulate through poorly maintained building ventilation systems
FIGURE Size comparison of virus and bacteria
https://onelife.eco/technology/
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Indoor Pollutants – Radon
Air Purification❑ Radon
• Radon is a dense, colorless, odorless noble gas that occurs naturally in the soil as the product of the radioactive decay of radium
• Radon is a major source of indoor air pollution and is the cause of tens of thousands of deaths annually in the US and Europe
FIGURE Radon pathways to home
http://wisehomeinspection.com/radon-testing/
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History of Air Purifier
Air Purification❑ The first air purifier
• In the late 19 century, the air pollution in the Western society intensified as industrialization progressed
• Dr. Frederick Cottrell developed a Electrostatic Precipitator,
filtering dust in the air by using static shock in the Oakland of California
FIGURE Frederick Gardner Cottrell's
‘Electrostatic Precipitator' patent
http://www.wip-news.com
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History of Air Purifier
Air Purification❑ HEPA filter
• As development of atomic
bomb was discussed in US, strict level of necessity for air purifying was raised for workers who had worked in the radiation factory
• HEPA (High Efficiency
Particulate Air) filter composed of several wrinkle filter like a
paper was invented
FIGURE George T Cartie's 'HEPA filter' patent
http://www.wip-news.com
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Air Purification Technology
Air Purification❑ Air purifiers
• (1) HEPA (High Efficiency Particulate Air) air purifier
• (2) Electrostatic air purifier
• (3) Negative-ion air purifier
FIGURE Classification of air purification technologies
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Air Purification Technology - HEPA
Air Purification❑ HEPA filter
• Impaction: capturing particles>1 ㎛
• Interception: capturing particles>0.1 ㎛
• Diffusion: capturing particles<0.1 ㎛
FIGURE The primary mechanisms of HEPA filter
Filtration Mechanism
https://ko.wikipedia.org/wiki/HEPA
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Air Purification Technology - HEPA
Air Purification❑ HEPA filter
• The classes of filters are defined by their retention at the given most penetrating particle size
TABLE The filter specification used in EU
https://ko.wikipedia.org/wiki/HEPA
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Air Purification Technology - HEPA
Air Purification❑ HEPA air purifier
• Prefilter catches large particles like hair and dust
• HEPA filter catches 99.9% of particles to 0.1 microns including pet dander and pollen
• Activated carbon filter absorbs and eliminate VOCs
FIGURE Process of air purification using HEPA filter
Pre-filter HEPA filter Activated carbon filter
https://www.whirlpoolairpurifiers.com/hepa-charcoal/
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Air Purification Technology - Electrostatic
Air Purification❑ Electrostatic air purifier
• Electrostatic air purifier consists of wires and collection plates
• With a high voltage applied from an electrostatic field between the wires and the collecting plate, the air is charged
electrically and ionized in the process
FIGURE Electrostatic precipitation process
https://oransi.com/blogs/blog/electrostatic-precipitator
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Air Purification Technology - Electrostatic
Air Purification❑ Electrostatic air purifier vs HEPA air purifier
FIGURE Comparison of electrostatic and HEPA air purifier
Electrostatic air purifiers have a 60- 80% first-pass efficiency rate and require a longer amount of time to improve indoor air quality
HEPA air purifiers typically have an 87-99% first-pass efficiency rate, meaning HEPA air purifiers catch more particles faster
Electrostatic
air purifier HEPA
air purifier
Even if electrostatic air purifiers are cleaned regularly, their performance will decrease over time
As long as HEPA air purifiers’ filter changes within 6-8 months, it will continue to perform well
vs
https://alen.com/pages/hepa-air-purifiers-are-more-effective-than-electrostatic-air-purifiers
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Air Purification Technology - Negative-ion
Air Purification❑ Negative-ion air purifier
• Air ionizers work by emitting negative ion charges into the air
• Unlike electrostatic air purifier, negative-ion air purifier does not need a fan to function
FIGURE negative-ion air purifier process
https://www.teqoya.com/doctor-medical-office/
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Air Purification Technology - Negative-ion
Air Purification❑ Negative-ion air purifier vs HEPA air purifier
TABLE Comparison of negative-ion and HEPA air purifier
Type Negative-ion air purifier HEPA air purifier
Pros
• Costs less money to run
• Able to clean air in a large space
• Efficiently filters out particles quickly
• Traps particles in filter to completely remove them from the air in your home
Cons
• Does not efficiently filter out particles
• Need to vacuum house regularly
• Creates ozone air pollution
• Costs more money to run in the long term (disposable filter replacement)
• Can be noisy from fan blowing air around
https://hvactrainingshop.com/ionic-vs-hepa-air-purifiers/
Thermoelectric
Device
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Seebeck Effect & Peltier effect
Thermoelectric DeviceTemperature difference, at junctions of two dissimilar metals, can make voltage (Seebeck effect, 1821)
FIGURE Instrument used by Seebeck to observe the deflection of a compass needle
http://thermoelectrics.matsci.northwestern.edu/thermoelectrics/history.html
Thomas Johann Seebeck (1770 ~ 1831)
Jean Charles Athanase Peltier (1785 ~ 1845)
A voltage can produce heating or cooling at the junction of two dissimilar metals
(Peltier effect, 1834)
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Thermoelectrical Materials-Semicondoctors
❑ N-type semiconductor
• Semiconductor doped with donor impurities.
• It has more free
electrons than holes.
• It is easily excited into the conduction band.
❑ P-type semiconductor
• Semiconductor doped with acceptor impurities.
• It has more holes than free electrons.
• It allow excitation of valence band electrons.
FIGURE “N-type" vs. “P-type" semiconductor structure
http://hyperphysics.phy-astr.gsu.edu/
FIGURE Bands for doped semiconductors Thermoelectric Device
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Thermoelectric Generation (TEG)
Thermoelectric DeviceMark S. Lundstrom, nanoHUB-U Thermoelectricity L2.3:
Thermoelectric Transport Parameters - Devices and Materials
FIGURE Schematic of thermoelectric generation (TEG)
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Thermoelectric Cooling (TEC)
Thermoelectric DeviceMark S. Lundstrom, nanoHUB-U Thermoelectricity L2.3:
Thermoelectric Transport Parameters - Devices and Materials
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Thermoelectric Devices
Thermoelectric DeviceFIGURE Thermoelectric generation (TEG) and thermoelectric cooling (TEC)
남우현 외, 나노구조 기반 중·고온용 열전소재 연구 동향 (2019)
❑ TEG: Temperature difference ⇒ Voltage (Seebeck effect)
❑ TEC: Voltage ⇒ Temperature difference (Peltier effect)
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Thermoelectric Module
Thermoelectric DeviceFIGURE (a) Working principle and (b) components of a typical thermoelectric cooler.
Kumar et al., The design of a thermoelectric generator and its medical applications (2019)
• Electrical circuits are constructed in series.
• Thermal equivalent circuits are constructed in parallel.
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Pros and Cons of TEC
Thermoelectric DeviceFIGURE TEC module
❑ Pros
• Compactness and Quietness
• Available for localized heating and cooling
• Environmentally friendly
• Accurate temperature control (±0.01 K)
• Fast response
• Low maintenance cost
❑ Cons
• Large electrical power requirements
• Inefficient compared with phase change cooling
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Current TEC Application
Thermoelectric Device• Currently, TEC is used in small systems where vapor compression heat pumps are difficult to apply.
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Current TEG Application
Thermoelectric DeviceJaziri et al., A comprehensive review of Thermoelectric Generators: Technologies and common applications (2020)
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Future TEC Application
Thermoelectric Device47/42 Environmental Thermal Engineering
Future TEG Application
Thermoelectric Device1.0 1.5 2.0
zT 3.0
Special field (Spaceship, military)
Waste heat of vehicle Waste heat of industry
Geothermal Micro power supply
FIGURE TEG application roadmap
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Figure of Merit of Thermoelectric
Thermoelectric Device남우현 외, 나노구조 기반 중·고온용 열전소재 연구 동향 (2019)
zT = 𝜎𝛼
2𝑇 𝜅
Demensionless figure of merit, zT
𝜎: Electrical conductivity [S/cm]
𝛼: Seebeck coefficient [V/K]
𝑇: Average temperature of
heat source and heat sink [K]
𝜅: Thermal conductivity [W/cm·K]
❑ Problem
• Carrier concentration increase ⇒ electrical conductivity increase
• However, Seebeck coefficient decrease and thermal conductivity increase. ⇒ Maximum ZT value is small
FIGURE Thermoelectric properties vs.
carrier concentration (nc)
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Figure of Merit of Thermoelectric
Thermoelectric DeviceYu et al., Near-room-temperature thermoelectric materials and their application prospects in geothermal power generation (2019)
𝜂𝑚𝑎𝑥 = 𝑇𝐻−𝑇𝐶
𝑇𝐶
1+𝑧𝑇−1 1+𝑧𝑇+𝑇𝐶/𝑇𝐻
𝐶𝑂𝑃𝑚𝑎𝑥 = 𝑇𝐶
𝑇𝐻−𝑇𝐶
1+𝑧𝑇−𝑇𝐻/𝑇𝐶 1+𝑧𝑇+1
zT = 𝜎𝛼
2𝑇 𝜅
FIGURE Hot-side temperature
dependence of the TE energy conversion efficiency for different zT values.
• Currently, commercially available TEG device has zT value of 0.7.
• If the zT value does not increase significantly, the efficiency is very low compared to other power generation. Therefore, a study to increase the zT value is required.
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Figure of Merit of Thermoelectric
Thermoelectric DeviceZhang et al., Thermoelectric materials: Energy conversion between heat and electricity (2015)
FIGURE zT of the current bulk
thermoelectric materials as a function of year
• As nanotechnology is applied, the performance of thermoelectric devices is rapidly increasing.
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Promising Nano Candidates for Thermoelectric
Thermoelectric DeviceOh et al., Significantly reduced thermal conductivity and enhanced thermoelectric properties of single- and bi-layer graphene nanomeshes with sub-10 nm neck-width (2017)
❑ Graphene
• Graphene has high Seebeck coefficient and electric conductivity.
However, generally it also has high thermal conductivity.
• Some research groups are working on overcoming this difficulty with doping, etc.
FIGURE TEM images of the SGNM films and thermal conductivity of SGNMs
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Promising Nano Candidates for Thermoelectric
Thermoelectric Device김동호 외, 열전냉각소자 신기술 개발 현황 (2004)
❑ Superlattices
• Layered materials, with layer thicknesses on the order of nanometers, are being tested.
FIGURE Thermoelectric cooling device using superlattice nanostructure (a)MIT (b)RTI
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Promising Nano Candidates for Thermoelectric
Thermoelectric DeviceDresselhaus et al., New Directions for Low-Dimensional Thermoelectric Materials (2007)
❑ PbTe and PbSeTe quantum dot superlattices
• Using conventional thermoelectric materials on the nanoscale can increase zT and help when material costs are high.
FIGURE (a) Schematic drawing of a QDSL and (b) TE figure of merit vs. temperature for an n-type PbSe0.98Te0.02/PbTe QDSL sample
Fuel Cell &
Hydrogen Society
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Global Warming
IntroductionModel for predicting temperature rise due to greenhouse gas reduction
1.5℃
2100
?
Source: IPCC report 2018
❑ 2015 Paris United Nations Framework Convention on Climate Change → 2℃ limit
❑ 2018 Intergovernmental Panel on Climate Change (IPCC) → Special Report 1.5℃ limit
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Why global warming?
IntroductionGlobal mean surface temperature due to human and environmental factors 1.5˚C
1.0˚C
0.5˚C
0.0˚C
-0.5˚C
1850 1875 1900 1925 1950 1975 2000 Land Use
All Factors Ozone
Aerosols Volcanoes
Greenhouse Gases Solar
Observed
Temperature Change
Source: Carbon Brief, Analysis: Why scientists thinks 100% of global warming is due to humans, 2017.12.13
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What’s causing global warming?
IntroductionCarbon dioxide 63%
Methane 19%
Etc.19%
Water vapor 63%
Carbon
dioxide 6% Methane 2%
Etc. 2%
Global warming contribution
Including water vapor Excluding water vapor
Source: CDIAC 2016 / Robinson 2012
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Fuel cell working principle
Fuel Cell FundamentalsCathode
H2 → 2H++2e-
O2+4H++4e- → 2H2O
2H2+O2 → 2H2O
2
2 2
of products of reactants ( ) ( ) 1( )
2
f f f
H
H O O
f f f f
g g g
g g g g
= −
= − −
2 gf
E F
= −
H
2H
2Anode Cathode
O
2H
2O
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How does it work?
Fuel Cell FundamentalsCatalyst Layer Electrolyte Gas Diffusion Layer
Gas Diffusion Layer
H H O O
1 1
3 3
4 4
2
H
+H
2H
2Catalyst Layer
Anode Inlet Cathode Inlet
Anode Outlet Cathode Outlet
2 e
❑ Fuel Cell working principles
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Fuel cell electrochemical reaction animation
Fuel Cell FundamentalsSource: https://www.youtube.com/watch?v=K593QzqJUQk&ab_channel=FreudenbergGroup, 2019.04.15
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Fuel cell stack
Fuel Cell FundamentalsEndplate
(for compression)
Electrode
(for power output)
A single fuel cell
Gasket &
Bipolar plate
GDL &
MEA stacking
Flow Channel
Air
Hydrogen Coolant
❑ Fuel cell stack: Individual fuel cells are combined in series
❑ Fuel cell stack power increase
• Voltage: Stacking fuel cells (working potential: 0.6 ~0.9 V / cell)
• Current: Electrode area increase
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Fuel cell performance curve
Fuel Cell Fundamentals1.4
0 200 400 600 800 1000
0.0 0.2 0.4 0.6 0.8 1.0
1.2 P= IVcell
0.7
0.0 0.1 0.2 0.3 0.4 0.5 0.6
= - - -
❑ Performance
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Fuel cell vehicle - Nexo
Fuel Cell SystemSource: Hyundai Group homepage, 2020.10.03
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Fuel cell station
Fuel Cell System상암 H2 Station Hydrogen fueling
Source: 서울특별시 뉴스, “상암수소충전소’ 이용하려면?’ 2020.10.23
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Fuel cell vehicle structure
Fuel Cell SystemHydrogen Supply System
Air Supply System
Purified Humid Air Supply
Thermal Management System
Fuel Cell Stack Temperature Control
High Voltage Battery
Electric Energy Storage & Supply
Electric Motor & Reducer
Vehicle Driving Force
Fuel Cell Stack
Electrochemical reaction 𝟐𝐇𝟐 + 𝐎𝟐 → 𝟐𝐇𝟐𝐎
Hydrogen Storage system
Hydrogen Gas (700bar)
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Fuel cell system schematic
Fuel Cell SystemHydrogen Supply
Air Supply Water Management
Thermal Management Electric / Control
Hydrogen
Tank Hydrogen Blower FilterAir
Water Trap Ejector
Air compressor
Humidifier
De-ionizer
Radiator
Water pump
Reservior Radiator Fan
Controller DC/DC
Converter
Stack
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Fuel cell applications
Fuel Cell SystemFuel Cell Stack Flow Field
Automobile Residential
Residential FC
Power Plant
Drone
FC scooter
FC airplane FC drone
Transportation
FC ship
FC tram
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Hydrogen supply chain
Hydrogen Society69/42 Environmental Thermal Engineering
How to produce hydrogen (H
Hydrogen Society 2)?
Cave
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How to storage hydrogen (H
Hydrogen Society 2)?
Compressed
hydrogen Gas H2 Ammonia NH3
Liquid organic hydrogen carrier
Toluene+H2
Liquified hydrogen
LH2 VolumeEnergy
Density(kg/m3) 38.0 120.3 47.1 70.9
Advantages • Small H2 Loss
• Widely used
• Energy density
• Use of existing infrastructure
• Long-term storage
• Use of existing infrastructure
• High safety
• Easy to use (Vaporization)
Disadvantages • High cost tank
• Low energy density
• Handling cost (Odor, Toxicity)
• R&D stage
• Need additional Energy
• Liquefaction Energy
• Need plant for liquefaction
Pictures
High pressure
gas tank Liquid ammonia
tank LOHC Liquid H2 tank
Source: Linde® / 현대자동차 / 에너지신문 / ㈜산업경제리서치
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Hydrogen circulation
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Hydrogen society
Hydrogen SocietyH2Pipe
Electrolytic Device
Organic Matter H2Production
H2Transportation H2
Extraction
Liquid H2
FCEV Car sharing
Cryogenic Pump
H2Storage
Compressed H2 Transportation
H2bus
H2bicycle H2Ship Power Supply
FCEV
Source: Linde, “Hydrogen Applications Today and Tomorrow”, Hydrogen Council, 2018.07.24
Negative Pressure
Isolation Room
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Negative Pressure
Negative Pressure Isolation RoomFIGURE Definition of pressure FIGURE Definition of diverse pressure
❑ Pressure
• The force applied perpendicular to the surface of an object per unit area over which that force is distributed
❑ Negative “Gauge” Pressure
• Gauge Pressure – The pressure relative to atmospheric pressure
• Absolute pressure below 1 atm is called negative pressure
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Negative Pressure Isolation Room
Negative Pressure Isolation RoomFIGURE Schematic of negative pressure room
❑ Negative Pressure Isolation Room (NPIR)
• A type of hospital room that keeps patients with infectious illnesses, or patients who are susceptible to infections from others, away from other patients, visitors, and healthcare staff
• The air pressure inside the room is lower than the air pressure outside the room, so when the door is opened, potentially
contaminated air or other dangerous particles from inside the room will not low outside into non-contaminated areas
https://ko.wikipedia.org/
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Why do we need?
Negative Pressure Isolation Room❑ Covid-19
• An infectious disease caused by the SARS-CoV-2 virus
• The virus can spread from an infected person’s mouth or nose in small liquid particles when they cough, sneeze, speak, sing or breathe
FIGURE Schematic of negative pressure room
• Since the air rushes into the room when a door is opened, the germs all stay inside the room with the patient
• When the air leaves the room, it must go thorough a HEPA filter
before recirculating throughout the hospital
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HEPA filter
Negative Pressure Isolation Room❑ HEPA filter
• An acronym for “high efficiency particulate air”
• HEPA filter is a type of
pleated mechanical air filter
• This type of air filter can
theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (μm)
FIGURE HEPA filter
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Configuration of NPIR
Negative Pressure Isolation Room❑ Negative pressure isolation area
• An area with lower negative pressure than non-negative
pressure areas including wards, annexes, and essential support facilities for treating patients with high-risk infectious diseases
❑ Non-negative pressure zone
• An area adjacent to the negative pressure zone in which a
nursing station is installed to prepare for treatment of patients with infectious diseases and to observe the patient’s condition
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Configuration of NPIR
Negative Pressure Isolation RoomFIGURE Negative pressure ward and anteroom
❑ Negative pressure isolation ward
• A ward in which an infectious disease patient is admitted in the inpatient treatment area.
• A continuous negative pressure is maintained inside the ward, and shower facilities and toilets that can be accessed directly from the ward
❑ Anteroom
• A space for preparing for basic infection prevention, prevent air infection and plays a role in maintaining the negative pressure
https://www.priceindustries.com
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Facility standards
Negative Pressure Isolation Room❑ Facility standards
• The negative pressure isolation room should be physically separated from the general area of the hospital and divided into a negative and a non-negative pressure area
• In the negative pressure isolation area, all corridors, changing rooms, anterooms, wards and toilets, waste treatment room, equipment storage room, etc. are arranged and the nursing station is designed to facilitate observation
FIGURE Negative pressure tent
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Structure of NPIR
Negative Pressure Isolation RoomFIGURE Negative Pressure Isolation Room Structure
https://www.gyeongnam.go.kr/
❑ Structure of NPIR
• There are two main passages to and from the negative pressure room which is divided into medical and patient use
• There are also anteroom at the entrance to the hallway where patients enter.
• There are two automatic door between hallway to anteroom and anteroom to the ward
• These two doors never open at the same time in order to prevent the
possible airborne infection
• The pressure difference between each room must be maintained at least 2.5 Pa
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Structure of NPIR
Negative Pressure Isolation Room❑ Negative Pressure Anteroom
• Pressure drops hall, anteroom, ward, bathroom respectively
• Air control is relatively easy
• If the patient in the ward is infirm, this may cause additional infection by the inflow of external pollutants
FIGURE Negative Pressure Anteroom
❑ Structure of NPIR
• Most commonly used structure of the NPIR is the Hall- Anteroom-Ward-Bathroom
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Structure of NPIR
Negative Pressure Isolation RoomFIGURE Positive Pressure Anteroom
❑ Positive Pressure Anteroom
• Structure with the positive pressure anteroom
• It has advantage of protecting the patient in the ward from the external pollutants while the door is closed
• The defect is that the medical staff from the ward to the anteroom may draw the air from the ward to outside
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Automatic control
Negative Pressure Isolation Room❑ Automatic control of negative pressure isolation rooms
• An air conditioning control system that controls the negative pressure isolation room to always maintain the negative
pressure ,proper temperature and humidity.
https://www.johnsoncontrols.com/
FIGURE 3D image of a NPIR with HVAC Controls pop outs
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NPIR of Korea
Negative Pressure Isolation Room❑ SARS (2003)
• After SARS, we have been building negative pressure
isolation rooms since 2006, starting with the National medical Center
❑ NPIR of Korea have been developed with major epidemics
https://www.medpagetoday.com/
FIGURE SARS virus
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NPIR of Korea
Negative Pressure Isolation Roomhttp://ready.nj.gov/
❑ Pandemic influenza (2009)
• After the 2009 pandemic influenza in Korea, the Korea
centers for Disease Control and Prevention (KCDC) revised the ‘Act on the Prevention and Management of Infectious Diseases’
• ‘Regulations on the Operation of National Hospitalized Treatment Beds’ in 2010 established a legal basis for nationally designated inpatient treatment beds
FIGURE Pandemic influenza virus
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NPIR of Korea
Negative Pressure Isolation Room❑ MERS (2015)
• When MERS broke out in 2015, group infections were carried out through domestic medical institutions, further
strengthening facility standards and expanding the scale.
• In particular, the related laws have been strengthened to
ensure that general hospitals with more than 300 beds have negative pressure isolation rooms.
https://dongascience.com/
FIGURE MERS virus
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NPIR of Korea
Negative Pressure Isolation Roomhttps://easl.eu/
❑ Covid-19 (2019)
• As of 2011, the nationally designated inpatient
treatment(isolation) beds were 360 beds (69 negative
pressure beds, 291 general beds) in 10 hospitals across the country
• Currently, the scale has been expanded to 566 beds (194 negative pressure beds, 372 general beds) in 29 hospitals across the country
FIGURE Covid-19 virus
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Law about the NPIR
Negative Pressure Isolation Room❑ There are related regulations in the Enforcement Regulations of the Infectious Disease Prevention and Control Act Article 31, Paragraph1, Item 1
❑ Installation Duty
• Infectious disease control institution with 300 or more beds : Install at least one negative pressure room that meets the criteria
• Infectious disease control institution with less than 300 beds : At least one isolated treatment room or isolated ward should be installed
• If a negative pressure room is not installed, a corrective order may be issued under the medical Act
• Also, if a tertiary general hospital does not install a negative pressure room, the designation of a tertiary general hospital will be cancelled
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Law about the NPIR
Negative Pressure Isolation Room❑ Installation Criteria
• Negative pressure bed : Secure an area of 15m2 or more
• Anteroom : Install in a place that can physically separate the negative pressure area with the negative pressure bed and the non-negative pressure area
• Toilet : install in a space with a negative pressure bed
• Supply/discharge facility for negative pressure : Install it separately from other supply/discharge facilities, and install a HEPA filter
• Negative pressure backflow prevention facility : to be installed on the pipe in the space where the negative pressure bed is located
• Negative pressure drainage treatment and collection tank : install separately from other drainage treatment and
collection facilities
Solar Power
Generation System
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Solar Power Generation System
Solar Power Generation System• Very low running cost
• No mechanical vibration, no noise
• Life of solar cell is more than 20 yrs
• Infinite energy source
• No pollutant generation Advantages
• High initial cost
• Variation of energy generation since cloudy or rainy weather
• Need large area
• Low energy density Disadvantages
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Classification
Solar Power Generation System❑ Photovoltaic system
• Photo + Volta
Converts the energy of light directly into electricity by the photovoltaic effect
FIGURE Solar power tower at Crescent Dunes Solar Energy Project
FIGURE Concentrator photovoltaics modules on dual axis solar tracker in Golmud, China
❑ Solar heat system
(CSP: Concentrated Solar Power)
• Generation with solar heat, useful for power plant
• Use mirrors or lenses to concentrate a large area of sunlight onto a receiver
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Photovoltaic System
Solar Power Generation System❑ Component
• Solar photovoltaic array
• Change controller
• Battery bank
• Inverter
• Utility Meter
• Electric Grid
❑ Photovoltaics(PV) : Conversion of light into electricity using semiconducting materials
• A common single junction silicon solar cell can produce a
maximum open-circuit voltage of approximately 0.5 to 0.6 volts
FIGURE Diagram of the components of a Photovoltaic system
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Photovoltaic System
• The light’s energy called photons, falls onto a solar panel and creates an electric
current through a process called the photovoltaic effect.
• The electricity produced is in the form of direct current (DC), so it must first be converted from DC to AC using an inverter.
• This AC electricity from the inverter can then be used, or be sent on to
the electrical grid for use Solar Power Generation System
FIGURE Photovoltaic System
Solar Photovoltaic Systems in the UK (2021) | GreenMatch
❑ Process of Photovoltaic generation
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Solar Power Generation System
Photovoltaic System
❑ Standalone system
Automatic solar system that produces electrical power to charge banks of batteries during the day for use at night when the suns energy is
unavailable.
❑ Grid connection system
The photovoltaic panels or array are connected to the utility grid through a power inverter unit allowing them to operate in parallel with the electric utility grid
Figure Configuration of standalone system
Figure Configuration of greed connection system