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Environmental Thermal

Engineering

Lecture Note #13

Professor Min Soo KIM

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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

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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 Purification

FIGURE 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/

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Thermoelectric

Device

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Seebeck Effect & Peltier effect

Thermoelectric Device

Temperature 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 Device

Mark 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 Device

Mark S. Lundstrom, nanoHUB-U Thermoelectricity L2.3:

Thermoelectric Transport Parameters - Devices and Materials

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Thermoelectric Devices

Thermoelectric Device

FIGURE 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 Device

FIGURE (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 Device

FIGURE 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 Device

Jaziri et al., A comprehensive review of Thermoelectric Generators: Technologies and common applications (2020)

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Future TEC Application

Thermoelectric Device

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Future TEG Application

Thermoelectric Device

1.0 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 Device

남우현 외, 나노구조 기반 중·고온용 열전소재 연구 동향 (2019)

zT = 𝜎𝛼

2

𝑇 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 Device

Yu 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

2

𝑇 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 Device

Zhang 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 Device

Oh 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 Device

김동호 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 Device

Dresselhaus 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

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Fuel Cell &

Hydrogen Society

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Global Warming

Introduction

Model 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?

Introduction

Global 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?

Introduction

Carbon 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 Fundamentals

Cathode

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

2

H

2

Anode Cathode

O

2

H

2

O

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How does it work?

Fuel Cell Fundamentals

Catalyst Layer Electrolyte Gas Diffusion Layer

Gas Diffusion Layer

H H O O

1 1

3 3

4 4

2

H

+

H

2

H

2

Catalyst 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 Fundamentals

Source: https://www.youtube.com/watch?v=K593QzqJUQk&ab_channel=FreudenbergGroup, 2019.04.15

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Fuel cell stack

Fuel Cell Fundamentals

Endplate

(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 Fundamentals

1.4

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 System

Source: Hyundai Group homepage, 2020.10.03

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Fuel cell station

Fuel Cell System

상암 H2 Station Hydrogen fueling

Source: 서울특별시 뉴스, “상암수소충전소’ 이용하려면?’ 2020.10.23

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Fuel cell vehicle structure

Fuel Cell System

Hydrogen 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 System

Hydrogen 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 System

Fuel 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 Society

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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

Hydrogen Society

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Hydrogen society

Hydrogen Society

H2Pipe

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

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Negative Pressure

Isolation Room

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Negative Pressure

Negative Pressure Isolation Room

FIGURE 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 Room

FIGURE 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 Room

FIGURE 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 Room

FIGURE 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 Room

FIGURE 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 Room

http://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 Room

https://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

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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

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