Ship Disposal and Environmental Impacts

RESPONSIBLE SHIP DISPOSAL
After a ship has reached the end of its effective life, responsible disposal should immediately commence in accordance with the proper regulations and guidelines  set out by international environmental authorities such as the Basel Convention, United Nations Environmental Program (UNEP), and the IMO or International Marine Organization. Priority should be given to ships posing the greatest environmental risk and having the worst conditions. Ship Breaking and Green Ship Recycling is the best ship disposal method and the most environmentally friendly ship disposal option. This would be discussed in a separate article.

ILLEGAL SHIP DISPOSAL (examples)
These ships contained radioactive materials and toxic substances such as asbestos, PCB (polychlorinated biphenyl), lead, mercury, and other toxic chemicals. They have failed to follow the Basel Convention that hazardous wastes should be removed in accordance to environmentally sound procedures before scrapping, recycling, or disposal.
1. Clemenceau (Aircraft Carrier) - France
2. SS Norway (Passenger Ship) - Norway
3. SS Oceanic (Ocean Liner) - USA

METHODS OF SHIP DISPOSAL
1. Ship Breaking and Recycling
2. Ship Museum
3. Floating Drydock storage
4. Hulking - floating without  riggings and equipment
5. Artificial reef - sinking  ship for marine life, diving sites
6. SINKEX - Sinking Exercise, Navy live fire target program
7. Ship Donation
8. Sale

SHIP DISPOSAL METHODS & IMPACTS TO THE ENVIRONMENT:

Hulking
- Exposure of birds, marine life, and wildlife to harmful and toxic chemicals from aging ships
- Empty ships taking space
- Rotting, rusting ships contribute to water pollution
- Essentially a floating garbage, ship graveyard or cemetery

Floating Dry Dock
- Storm-water runoff contamination with dissolved metal particles
- Blasting using high pressure pumps to wash down salt, slime, biofouling, and paint produces wastewater containing harmful sediments
- Cleaning agents contain lead, anti-fouling, and persistent organic pollutants (POP)
- Submerged FDD can deter the passage of fish

Ship Museum
- Deterioration from outdoor weather conditions
- Wastewater from operations
- Use of environmentally unfriendly cleaning chemicals 

Artificial Reef
- Poor growth and survivability of branching corals
- Reefs attract certain sea creatures, but don't necessarily cause an increase in living matter
- Creates habitat for certain species but would harm the natural ecology
- Artificial reefs made of old ships consist of metal junk which replaces existing natural habitats for species
- Sinking ships alter natural habitats and the desired enhancement is not realized
- Decreases fish stocks by promoting concentrations of fish, which makes them easier to catch, thereby overfishing
- Successful artificial reefs have specific geometry that is designed for the purpose and must be located at the correct underwater location

Sink Exercise (SINKEX, Navy's live ship targeting program)
- Toxic wastes from the sunk ship and explosions pollute the oceans
- Adverse effect on the foodchain and sea foods that people eat
- Contaminated marine life showed high levels of toxicity and then decreased the numbers of species
- Opposes federal marine conservation efforts
- Media, environmentalists, and other groups consider SINKEX as federally irresponsible

Ship Breaking and Recycling
- Best ship disposal method and the most environmentally sound ship disposal option
- 99% of the material is recyclable and reusable
- Savings on production or import of iron, steel, and other metals for shipbuilding
- Supplies raw materials to steel mills, steel manufacturing plants and other businesses
- Generates jobs and revenue
- Shipbreaking is the only environmentally friendly option that uses "Green Ship Recycling" that properly remove and correctly process hazardous wastes at approved facilities
- Certified and approved Green Ship Recycling facilities require shipbreaking operations in compliance with relevant legislation and treaties such as the Basel Convention, The International Convention for the Prevention of Marine Pollution from Ships (MARPOL), United Nations Convention on the Law of the Seas ( UNCLOS), International Maritime Organization (IMO), United Nations Environmental Program (UNEP), The International Chamber of Shipping (ICS), The Rotterdam Convention on the Prior Informed Consent (PIC) Procedure for Certain Hazardous Chemicals and Pesticides in International Trade, and the Stockholm Convention on Persistent Organic Pollutants (POPs)

Green Ship Recycling Standards

BASEL CONVENTION --- http://www.basel.int/
The Basel Convention is a United Nations (UN) treaty that is aimed at the reduction of hazardous waste, promotion of environmentally sound management of hazardous wastes, and prevention of hazardous wastes illegal transfer from one state to another. The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal was adopted in Basel, Switzerland in March 1989. The Convention came into force on May 1992. There are currently 51 Signatories and 175 Parties. The United Nations Environmental Program (UNEP) is responsible for the implementation of the Basel Convention. The International Maritime Organization (IMO) and the International Labour Organization (ILO) are international organizations that are deeply engaged in addressing the issue of ship recycling.

What is Basel Convention's main purpose?
The primary purpose of the Basel Convention is to stop or ban industrialized countries from dumping toxic wastes into developing countries.

What are the Basel Convention's aims and objectives:
Click here to view complete list of aims and objectives
http://www.basel.int/TheConvention/Overview/tabid/1271/Default.aspx

Coverage of Basel Convention:
The Basel Convention covers hazardous wastes that are explosive, flammable, poisonous, infectious, corrosive, toxic, or ecotoxic.

Refusal of Export to the Ship Breaking Country:
- All parties are required to provide information about a proposed trans-boundary movement of hazardous wastes to the destination countries .
- An exporting country must refuse the export of a ship having hazardous materials if the destination country for ship breaking operations can not manage the hazardous wastes in an environmentally sound manner.

Which countries are the primary ship breaking destinations?
Ship breaking operations are done primarily in Bangladesh, India, China, Turkey and Pakistan. Why these countries? Primarily because of cheap labour markets and soft/problematic enforcement of environmental protection standards.

Which countries export ships for shipbreaking?
Industrialized European and Western countries.

What are the reasons why Basel Convention is violated?
GRIM reasons.
MONEY - rich countries sell their old garbage ships and don't want to spend money to process obsolete, decommissioned, end-of-life ships. IRRESPONSIBILITY - irresponsibility and neglect for human welfare and environmental protection. RECKLESSNESS - they (violators) just don't care! (except only caring about themselves). GREED - greed for more money, greed for more profit....yeah, don't reason out --- you know you are doing the wrong thing!
If you arrange all the first letters: M, I, R, G ---> it is GRIM spelled backwards............GRIM reasons.

Major negative effects of Basel Convention violations:
- Environmental pollution, Operational accidents, Disease

Primary Responsibility Before Exporting Ships for Shipbreaking:
Pre-cleaning of hazardous wastes is the financial and legal responsibility of the ship owner before exporting ships to Bangladesh, India, China, Turkey, Pakistan, and other developing countries.

Primary NGO Supporter of Basel Convention --- http://www.ban.org/
The Basel Action Network (BAN) is a Seattle-based charitable non-governmental organization (NGO) whose mission is to prevent the globalization of the toxic chemical crisis. BAN is the guardian, defender, and promoter of the Basel Convention and its decisions. BAN opposes the export of toxic wastes, toxic products, and toxic technologies from rich to poorer countries. BAN prevents the rich countries from turning the poorer countries into a dumping ground.

BAN is recognised by the United Nations Environment Program (UNEP) as the leading organization dedicated exclusively to issues regarding trade of toxic substances. BAN is regularly invited as NGO experts and stakeholders in internal meetings and policy deliberations. BAN also worked closely with the Organization of Economic Cooperation and Development (OECD) and other United Nations (UN) mandated environmental protection programs.

BAN advocates Green Shipbreaking. BAN ensures that all hazardous materials from US ships and vessels are properly removed before exporting or domestic processing.

Click here to visit the BAN website:
http://www.ban.org/

The Green Ship Recycling Standard
The purpose of the Green Ship Recycling (GSR) Standard is to establish an environmentally sound management and methodology in shipbreaking and recycling of ships. The main objective of the standard is preventing damage to human health and the environment. The Green Ship Recycling Standard is created by the NGO Platform on Shipbreaking. BAN, Greenpeace, and other non-governmental organizations (NGOs) formed the NGO Platform on Shipbreaking. The primary focus of the platform is the responsible ship breaking and disposal of ships. Upholding the letter and spirit of the Basel Convention and the Basel Ban Amendment, the NGO Platform's main purpose is to stop the developed (first world) countries from the unlawful dumping of toxic wastes to underdeveloped third world countries. The NGO platform endorses the principles outlined in the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal.


REQUIREMENTS & PROCEDURE PRIOR TO DISMANTLING/RECYCLING

Floating or Land-Based Re-use of Ships:
- Green Ship Recycling Facilities (GSRF) should favor re-use of ships over recycling
- GSRF shall promote and assist in the preparation of ships for historic preservation, retrofitting, restoration, refurbishing and repair of ships that have a viable and safe proposition for extended life as a structural ship.
- Alternative uses can include further life as a ship, housing, offices, hotels, museums, conference centers, etc
- Alternative uses are favorable as long as hazardous materials are sealed and made safe from release.

Ocean Dumping/Placement:
Green Ship Recycling Facilities shall not support or be involved in:
- preparing or selling ships and other similar structures for use as artificial reefs
- utilizing ships as artificial reefs
- dumping ships at sea or placing it in the marine environment
- other forms of aquatic dumping or sinking in aquatic environments
- scuttling a ship (deliberately sinking a ship by allowing water to flow into the hull)
- sinking ships as targets for military exercises

Legal Requirements, International & National Waste Trade Law:
- A Green Ship Recycling Facility will operate and ensure all business practices are fully consistent and in compliance with national and international waste trade laws.
- A Green Ship Recycling Facility will operate in a manner which will not require other facilities, persons, or other entities to violate any national or international laws.
- A Green Ship Recycling Facility shall abide and comply with the following list of legal instruments:
List of Relevant International and National Waste Trade Agreements:
• Basel Convention
• European Waste Shipment Regulation
• Organization for Economic Cooperation and Development (OECD) Recycling Agreement
• Waigani Treaty
• Izmir Protocol
• Bamako Convention
• Acuerdo Regional sobre Movimiento Transfronterizo de Desechos Peligrosos -- Centroamerica
• Basel Ban Amendment (Decision III/1 of the Basel Convention)
• The Asbestos Regulations (as amended) 1999 (United Kingdom)
• Toxic Substances Control Act (for PCBs import and export) (USA)

International Labor Law:
- GSRF must operate in accordance with International Labour Organization (ILO) Conventions and Recommendations and all applicable international labor laws and guidelines. 

Licensed and Permitted:
- A Green Ship Recycling Facility must have valid applicable licenses and permits for operations including hazardous waste management- Only fully licensed and permitted downstream waste management facilities are allowed.

Waste oils, fuel and sewage:
- Prior to any recycling operations: all waste oils, oily liquids, fuels, and sewage must be completely removed from the ship & managed in accordance with the regulations and guidelines set by the International Convention for the Prevention of Pollution from Ships (MARPOL) 

Downstream Environmentally Sound Management of Wastes/Materials:
- All Green Ship Recycling Facilites must have access and use of national downstream disposal facilities that can handle, manage, and dispose all hazardous wastes on board vessels including asbestos, toxic metal paints, residual fuels and oils.
- Materials and wastes containing PCBs and other persistent organic pollutants (POPs) in concentrations above 50 ppm must not be landfilled or otherwise disposed of

Environmental and Health Monitoring:
- Workers in GSR workplaces should be monitored at least once a year. This should include blood and hair sampling.
- Workplace environmental monitoring should be conducted at least once a year. This must include soil sampling, air sampling, and dust sampling for heavy metals, asbestos, and PCBs.

Community Support:
- A wide community support including from local fishermen, residents, and businesses should be obtained before the establishment of a new Green Ship Recycling Facility.

Environmental Management System (EMS):
- Green Ship Recycling Facilities will implement, maintain, and document an ISO (International Organization for Standardization) or similarly certified Environmental Management System

Fire Fighting Equipment:
- GSRF must have fire fighting equipment and capability to extinguish all types of fires inside and outside the ships and surrounding premises.

Occupational Safety and Health Responsibility:
- Occupational safety and health (OSH) is the responsibility and duty of the GSRF employer
- Owners of GSRF must periodically assess and identify risks and hazards to health and safety
- Preventive and Protective Measures should be implemented in conformity with ILO guidelines on shipbreaking and other relevant international conventions, regulations, recommendations, and codes of practice.

Personal Protective Equipment:
- Green Ship Recycling Facility owners must freely provide appropriate gloves, boots, coveralls, uniforms, googles, respirators, face shields, hardhats, and other personal protective equipment (PPE) to employees
- Proper use of PPE shall be enforced in accordance with ILO guidelines and OSH standards.

Onsite/Offsite Medical and Emergency Facilities:
- GSR Facilities must possess emergency eye-wash stations, emergency shower stations, and first aid supply & equipment
- During all operations, persons trained in First Aid Procedures must be present at all times
- Hospitals with rapid means of transport and capable of severe injury treatment must be located within 15 kilometers of a GSRF.
- Emergency response vehicles must be able to approach within 25 meters of at least one side of a ship without delay

Green Passport and Ship Recycling Plan:
- Before the Green Recycling Process initiates, two key documents are essential so that the Pre-Cleaning process can be planned and executed prior to the arrival of the ship at the recycling facility.

(a) Ship's Green Passport
- A ship's green passport is the vessel's document that contains the inventory of hazardous materials onboard.
- A Green Passport stays with the ship throughout its lifespan
- The Hazardous Materials Inventory (green passport) is the responsibility of the ship owner

(b) Ship Recycling Plan
- A Ship Recycling Plan is a document prepared by the Ship Recycling Facility during the sale of the vessel

Transboundary Voyage to Annex VII Destinations:
When the final destination of ships containing Basel listed hazardous wastes is an Annex VII country (member of OECD, EU, Liechtenstein), a Green Ship Recycling Facility must perform the following prior to the final voyage of all ships:

1. Full Inventory:
• A full inventory of Basel listed hazardous wastes remaining on the ship must be accomplished
• Inventory of hazardous wastes/materials shall include at a minimum: mercury, Polychlorinated Biphenyls (PCBs), ChloroFluoroCarbons (CFCs), lead, cadmium, tributyl tin (TBT), halogens, solvents, asbestos, fuel, radioactive materials, and oils and oily mixtures.

2. Testing and Examination by Licensed Experts:
• All testing and examination must be accomplished by licensed experts in the field to ensure safety and credibility of results.

3. Notification and Consent:
• Article 6 of the Basel Convention describing full notification and consent between competent authorities must be successfully completed.

4. Adherence to Standards:
• Ensure that the receiving facility is a Green Ship Recycling Facility that adheres to the standards.

Transboundary Voyage to Non-Annex VII Destinations:
When the final destination of ships containing Basel listed hazardous wastes is a non-Annex VII country (not OECD/EU/Liechtenstein), the exporting Green Ship Recycling Facility must perform:

1. Pre-cleaning:
- Pre-cleaning of ships in accordance to the standards before sending it to the final disposal destination
- Pre-cleaning is to be carried out by removing all Basel listed hazardous wastes and ensuring safe towing of the ship its final destination.

2. Processing of Hazardous Substances:
- Hazardous substances such as residual fuels, asbestos, polychlorinated biphenyls (PCBs) or toxic metals should be processed according to Basel Technical Guidelines for the environmentally sound management of the full and partial dismantling of ships.

3. Repatriation of Hazardous Wastes:
- Hazardous Wastes that cannot be removed because of resulting unsafe towing must be repatriated to the exporting Annex VII country for final disposition in a government approved disposal or recycling facility.


REQUIREMENTS & PROCEDURE DURING RECYLING

Gas-Free Testing & Certificates:
- Prior to any cutting or dismantling operations onboard a vessel in the GSRF, a ship must be tested for flammability and a Gas-Free for Hot Works certificate must be granted.

Environmentally and Occupationally Sound Management and Responsibility:
- All Shipbreaking and Recycling operations must be conducted in accordance with the Basel Convention Technical Guidelines, ILO Safety and Health in Shipbreaking, IMO guidelines on Ship Recycling, and other relevant guidelines including all applicable local and national laws.
- Environmentally Sound Management of Hazardous Wastes involves Waste Recovery and Disposal Methods
- Waste Recovery methods involve Regeneration and Reclamation through processes such as Distillation, Thin-Film Evaporation, and Steam Stripping
- Disposal Methods involve processes such as Biological Treatment, Physico-Chemical Treatment, Deep Injection, Specially Engineered Landfill, and Incineration on Land

No Beaching Operations:
- No Green Ship Recycling operations shall take place on tidal beaches
- Tidal Beaches provide unstable and impractical platforms for mechanical lifting devices such as cranes
- Tidal Beaches does not offer good access to emergency response vehicles
- Leaks from oils, residues, and particulate matter falling on tidal beaches are not retrievable

Full Containment & Operational Platform with Drydocks or Graving Docks:
- GSRF operational platforms are required to have impermeable floors where hazardous materials and wastes are handled
- Drydocks or graving docks with impermeable, contrallable and fully contained floored area is required 
- Impermeable Floors provide full containment for loss of liquids or particulate matters (e.g. oils, paint chips, dust)
- Impermeable Floors allow recovery and management of incidental or accidental releases of residues or emissions
- Drydock or Graving dock floors must be washed everyday
- Before flooding, floors must be thoroughly cleaned
- Wastewater shall be managed as hazardous waste because of cleaning agents, particles, and residues
- No part of the ship can be considered as the necessary containment
- Cutting and recycling activities shall not take place directly over water, soil, or sand

Asbestos Remediation and Disposal:
- All forms of asbestos must be removed, isolated and managed as hazardous wastes in downstream disposal facilities in compliance to GSR guidelines (Annex II) and applicable ILO Conventions   
- Asbestos must be managed in accordance with all applicable national and local laws, regulations, and guidelines
- Asbestos in any form must never be reused or recycled
- Asbestos must be disposed of in a secure landfill designed for asbestos without possibility of airborne or other releases.

PCBs Removal and Destruction:
- PCBs in liquid form are found in transformers, capacitors, and fluorescent light ballasts
- PCBs in solid form are found in gaskets, electronic cables, electrical wires, insulation, pliable flooring materials, roofing materials, and in paints.
- PCBs in both solid and liquid forms having concentrations greater than 50 ppm should be treated and managed as hazardous wastes [ 1 mg/1,000,000 mg (solid) or 1 ml/1,000,000 ml (liquid) --> one part in one million = 1 ppm (part per million) ]
- PCBs should be removed and isolated under the conditions and in facilities as described in the Basel Convention and relevant guidelines in the Green Ship Recycling standards document.
- PCBs must never be reused or recycled 
- PCBs will be subject to destruction technologies that destroy the PCB molecule with a total Destruction Efficiency (DE) of 99.9999 percent.

Radioactive Devices:
- Smoke detectors, ionizing smoke alarms, and all other ship equipment containing radioactive materials must be removed, collected, and managed in a designated radioactive waste facility that complies with national and international regulations.

Mercury:
- Mercury is usually found in ship's equipment, instruments, and devices such as electronic switches, relays, binnacles, compasses, thermometers, barometers, and in fluorescent light bulbs
- Mercury should never be released to the environment
- All mercury should be managed as hazardous waste and processed in a facility capable of safely recycling it
- Mercury recycling facilities should have retorts capable of 99.99% recovery.

ChloroFluoroCarbons (CFCs) / Freon Remediation and Disposal:
- CFCs found in refrigerants, air-conditioning equipment, fire extinguishers, etc. must be properly identified, safely removed and isolated.
- CFCs should never be released to the atmosphere
- Disposal must be implemented through a licensed CFC collector
- Management and Remediation (removal of CFC from environmental media such as soil and water) should be in accordance with MARPOL and Montreal Protocol obligations and guidelines.

Harmful Paints and Plastics:
- Paints and plastics should be tested for halogens and toxic metal contents such as lead, cadmium, and tributyl tin (TBT)
- Paints and plastics with hazardous levels of toxic metals should be processed as hazardous wastes
- Materials containing halogens must be placed in a secure and designated landfill area
- Steel and other metals having paints, coatings, and plastics containing halogens or toxic substances must be sent to smelters with effective pollution control devices and equipment
- Smelters must operate in high temperatures to prevent the release of toxic metals, dioxins, and harmful hydrocarbons

Burning and Incineration:
- Except for dedicated incinerators, no ship material should be burned as they can cause or create harmful emissions
- Only dedicated hazardous wastes incinerators with a 99.9999% destruction efficiency is allowed

Thermal Cutting:
- Thermal cutting, or other thermal operations or devices must not create toxic fumes or smoke
- Thermal operations should not be done near or over all paints, plastics and other materials that causes toxic gases

Toxic or Health Impairing Dusts:
- Grinding, sand blasting, cutting, and other operations that create toxic dusts or unhealthy dusts should be avoided
- If such operations cannot be avoided, appropriate respirators, masks, and protective equipment must be worn to prevent inhalation and eye exposure

Transport of Hazardous Wastes:
- Hazardous wastes for transport should be properly labeled, and packaged in accordance to regulations to prevent spill or release.

Downstream Due Diligence:
- For all operations away from the GSRF, owners must satisfy legal and safety requirements
- Ensure that Safety Measures must be in place to prevent dangers, hazards, and risks
- Third party facilities and brokers must meet applicable standards, must have all the permits and licenses for all waste management operations

Difference between Centrifugal pumps and Positive Displacement pumps

Centrifugal Pump

Centrifugal pumps use a rotary vane impeller to impart kinetic energy by increasing the velocity of the liquid. This high velocity of the liquid will then produce a velocity head and at the same time producing a high flow rate.

Characteristics of Centrifugal Pump:
- higher power costs
- not self-priming
- gives less pressure to the fluids being pumped
- delivers a variable volume of fluid depending on the fluid's discharge pressure
- well suited for high flow conditions
- flow rate of liquid pumped varies depending on the system pressure or pressure head
- flow rate is inversely proportional to the viscosity of the liquid (flow is decreased if the viscosity is increased)
- centrifugal pumps has practical applications in pumping liquids with low viscosity
- run at higher speeds than positive displacement pumps (PD pumps)
- lower tolerance for entrained gases

Types of Centrifugal pumps:
1. Axial Flow - single stage, multistage
2. Radial Flow (Mixed Flow) - single suction, double suction
3. Peripheral Flow - single stage, multi-stage

Uses and Applications of Centrifugal pumps:
- general water supply for buildings
- overhead and pneumatic tank systems
- domestic water supply systems
- dairy farmers
- hot-water circulating service
- shallow wells and in deep wells
- booster fire pumps for fire protection systems
- construction companies
- cooling of engines, automotive factories
- sump, sewage drainage
- can handle abrasive, corrosive, dirty fluids
- hygienic purposes such as food, pharmaceuticals    
- irrigation and agriculture purposes
- chemical, petrochemical, fertilizer plants
- ship's bilge pumping
- cryogenics industry in extreme cold applications
- electric and power generation industries
- beverage, softdrink, soda, pop, distillery corporations
- textile, fabric industries
- pulp, paper industry
- and more...

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Positive Displacement Pump

Positive displacement pumps apply a force (by using a piston, for example) to move a fixed volume of fluid inside the casing of the pump.

Characteristics of Positive Displacement Pump:
- lower power costs
- self-priming
- gives more pressure to the liquid being pumped
- delivers a constant volume of fluid even with varying discharge pressure
- used for low flow applications
- liquid pumped has a relatively constant flow regardless of the system pressure or pressure head
- flow rate is directly proportional to the viscosity of the liquid (flow is increased when viscosity is increased)
- positive displacement pumps are generally used for pumping liquids with high viscosity which in turn provides a higher volumetric efficiency
- creates a vacuum on the suction side of the pump thereby creating a suction lift
- higher tolerance for entrained gases

Types of Positive Displacement Pumps:
1. Reciprocating - piston/plunger, diaphragm
2. Rotary - single rotor, multiple rotor

Uses and applications of Positive Displacement Pumps:
- metering applications
- high viscosity application
- food, chocolate, beverage factories
- hazardous chemicals, slurries and pastes
- pharmaceutical products
- paint, resins, adhesives, glue industries
- fuel booster pumping systems
- lubricating oil systems
- pulp, paper, mill industry
- manufacturing applications
- diesel fuel handling and distribution 
- and more...

Carnot Vapour Compression Refrigeration cycle

The Carnot Vapour Compression Refrigeration cycle is the thermodynamic cycle that is widely used by commercial manufacturers and producers of refrigerators, air-conditioners, freezers, and other equipment for the same cooling and freezing applications. There are four major components involved in the Carnot vapor compression refrigeration and air conditioning cycle in which a refrigerant is used as a cooling medium that flows through these 4 components:

Evaporator
The low pressure, low temperature, liquid state refrigerant enters the Evaporator. The Evaporator through the refrigerant is used to absorb heat. In the Evaporator is where the cooling of the items that you put inside your fridge take place. Heat exchange will take place between the refrigerant and the heat sources. The food items will then be cooled down while the previously cold refrigerant will be heated up and be turned to vapor. The boiling point (saturation temperature) of the refrigerant must be lower than the temperature of the heat source (such as food, drinks, beverage, vegetables, fruits that you put inside your fridge) so that by the 2nd Law of Thermodynamics, "Heat flows from a hot body to a cold body", the heat will flow from the heat source to the refrigerant. Upon exiting the Evaporator and absorbing the heat, the previously liquid refrigerant is now turned into a low pressure, high temperature, gas/vapor state refrigerant.

Compressor
The low pressure, high temperature, gas/vapor state refrigerant enters the Compressor. In order for the refrigerant to reject the heat (in order for the refrigerant to get cooled down) in the condenser, the boiling point or saturation temperature of the refrigerant must be higher than the condenser (heat sink) temperature. The purpose of the Compressor is to raise the saturation temperature of the refrigerant as well as to increase the refrigerant's pressure. Upon exiting the Compressor, the previously low pressure, high temperature, gas/vapor state refrigerant is now turned into a gas or vapor state refrigerant with high pressure, and higher temperature than when it entered the Compressor.

Condenser
The high pressure, high temperature, gas state refrigerant enters the Condenser or Heat Sink. The purpose of the Condenser is to cool down and condense the vapor state refrigerant and turn it into a liquid state refrigerant. Typical condensers used in refrigeration and air-conditioning are Air-cooled Condensers which are basically made up of multiple thin coils that are used to liquefy the refrigerant and discharge the heat to the surrounding air or atmosphere in the environment. When the refrigerant exits the Condenser, it is now high pressure, high temperature, and in liquid form.

Thermal Expansion Valve
The high pressure, high temperature, liquid state refrigerant enters the Thermal Expansion Valve (TEV). The purpose of the  TEV is to lower down the pressure and bring back the refrigerant to its original saturation temperature so that the cycle is completed and prepares the refrigerant to start another cycle. Another important function of the TEV is to regulate the amount of flow of liquid refrigerant to the evaporator. This is determined by how much food and drink items were place in your refrigerator and how cold you want them to be. The thermostat, (the usually circular button that has numbers indicating Cold, Colder, Coldest) that you turn inside your fridge is where you control to the desired settings. On the exit to the Thermal Expansion Valve, the refrigerant is now turned into low pressure, low temperature, liquid refrigerant that is now again ready to absorb heat from whatever food, drink, milk, fruits, veggies, cheese, soda, and other heat sources that you place inside your fridge or refrigerator. Thus completes the Carnot Vapour-Compression Refrigeration cycle.


See also:
1. Basics of Refrigeration and Air Conditioning
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MECHANICAL ENGINEERING: Reliability of a product, failure, failed products, total manufactured

R = 1 - f/m


where:

R = reliability of a product, a measure of the product's probability that it will not fail when used

f = number of failed products

m = number of manufactured products


1. A certain bearing and gear manufacturer has produced a total of 4000 ball bearings and 5000 spur gears. It was later found out that there were 35 ball bearings and 70 spur gears that failed. Determine the Reliability of the class of ball bearings and these kinds of spur gears.


ball bearings:

find:

R = Reliability of these kinds of ball bearings


given:

f = 35

m = 4000


solution:

R = 1 - f/m

R = 1 - 35/4000

R = 1 - 0.0088

R = 0.9912  or 99.12%


spur gears:

find:

R = Reliability of these specific types of spur gears


given:

f = 70

m = 5000


solution:

R = 1 - f/m

R = 1 - 70/5000

R = 1 - 0.014

R = 0.986  or 98.6%

MECHANICAL ENGINEERING: Thermodynamics - Entropy and the Second Law of Thermodynamics

Entropy

- a measure of a system's energy that is unavailable for work

- a measure of the disorder or randomness

- from Greek entropia "a turning towards"



Second law of thermodynamics

- there is no machine with 100% efficiency

- phenomenon of irreversibility in nature

- In a system, a process that occurs will tend to increase the total entropy of the universe

- The entropy of an isolated system which is not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium

- It is impossible for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow

- It is impossible to extract an amount of heat from a hot reservoir and use it all to do work. Some amount of heat must be exhausted to a cold reservoir



Few examples of Entropy and the 2nd Law of Thermodynamics

- flow of heat from a hot object to a cold object

- flow of a gas from high pressure to low pressure

- evaporation of water

- melting of ice

- cloud formation in the sky

- adding sugar to a cup of coffee

- carbon dioxide is dissolved in water

- spontaneous (natural) cleaning of a messy house

- shuffling of playing cards

- breaking a mirror or glass



1. Isothermal and reversible process


dS = Q/T


where:

dS = change in entropy, values can be (+)increase or (-)decrease

Q = heat, negative (-) if heat removal, positive (+) if heat addition

T = absolute temperature




2. Temperature not constant


dS = Integral (dQ/T)


dQ = m * c * dT


substituting,

dS = Integral (dQ/T)

dS = Integral (m * c * dT/T)

dS = m * c * Integral (dT/T)


if

T1 = initial temperature

T2 = final temperature


dS = m * c * Integral(T1,T2) (dT/T)


then


dS = m * c * ln T2/T1


where:

m = mass

c = specific heat

dS = change in entropy, values can be (+)increase or (-)decrease

dQ = heat, negative (-) if heat removal, positive (+) if heat addition

T = absolute temperature




1. Find the change in entropy if 1 kg of water at 20 C is changed into ice at 0 C.


find:

dS = total change in entropy


given:

m = 1 kg of water

c of water = 4.2 kJ/kg K

lf = heat of fusion of ice = 334 kJ/kg

T1 = 20 C + 273 = 293 K

T2 = 0 C + 273 = 273 K


solution:

dS = dS1 + dS2


dS1 --> cooling of water


dS1 = m * c * ln T2/T1

dS1 = 1 * 4.2 * ln 273/293

dS1 = - 0.3 kJ/K


dS2 --> freezing of water to ice

dS2 = Q/T


but

Q = - m * lf  --> latent heat


note: Q is negative (-) because of HEAT REMOVAL


substituting,

dS2 = - m * lf/T

dS2 = - 1 * 334/273

dS2 = - 1.22 kj/K


total change in entropy

dS = dS1 + dS2

dS = (- 0.3) + (- 1.22)

dS = - 1.52 kJ/K




2. Calculate the change in entropy when 4 kJ of heat flows from the warm exterior at 40 C into a house at 22 C.


find:

dS = total change in entropy


given:

Q = 4 kJ

T exterior = 40 C + 273 = 313 K

T house = 22 C + 273 = 295 K


solution:

dS = dS exterior + dS house


dS exterior:


The entropy of the exterior decreases, since heat flows out of it (- Q)

dS exterior = -Q/T exterior

dS exterior = -4/313

dS exterior = -0.013 kJ/K



dS house:

The entropy of the house increases since heat flows into it (+ Q)

dS house = Q/T house

dS house = 4/295

dS house = 0.014 kJ/K



total change in entropy

dS = dS exterior + dS house

ds = -0.013 + 0.014

dS = 0.001 kJ/K

MECHANICAL ENGINEERING: Fluid Mechanics and Dynamics - Conservation of Mass, mass flow rate, volume flow rate

Volume = Area * height

V = A * h


if d = h = distance travelled by the cross-sectional area

V = A * d

and the Volume flow rate or the volume per unit time

Vdot = (A * d)/t


but d/t = velocity = v

Vdot = A * v


CONSERVATION OF MASS

The amount of mass that flows past any cross-section is constant

m1 = m2

mass in = mass out


but density D = m/V

m = D * V

substituting in

m1 = m2

D1 * V1 = D2 * V2


if V1 and V2 are volume flow rates and Vdot = A * v

D1 * (A1 * v1) = D2 * (A2 * v2)


the same fluid is flowing so

D1 = D2


and it simplifies to


A1 * v1 = A2 * v2


where:

A1 = cross-sectional area at point1

A2 = cross-sectional area at point2

v1 = velocity of fluid at point1

v2 = velocity of fluid at point2


1. Problem:

Water enters a pipe with diameter of 1 in at 7 fps. Determine the exit velocity of the water if the pipe diameter is 2 in.

find:

v2 = velocity of water at exit


given:

d1 = 1 in

d2 = 2 in

v1 = 7 fps


solution:

convert v1 to in/s

v1 = 7 ft/s * 12 in/ft

v1 = 84 in/s


solving for A1 and A2

A1 = pi/4 * (d1)^2

A1 = 0.785 * (1)^2

A1 = 0.785 * 1

A1 = 0.785 sq. in


A2 = pi/4 * (d2)^2

A2 = 0.785 * (2)^2

A2 = 0.785 * 4

A2 = 3.14 sq. in


by conservation of mass

A1 * v1 = A2 * v2

0.785 * 84 = 3.14 * v2

v2 = 21 in/s


convert v2 to fps

v2 = 21 in/s * 1 ft/12 in

v2 = 21/12

v2 = 1.75 fps


------------------

ALTERNATE SOLUTION:


A1 * v1 = A2 * v2


because (pi/4) and (sq. in) will cancel, there's no need for unit conversion

(d1)^2 * v1 = (d2)^2 * v2

(1)^2 * 7 = (2)^2 * v2

v2 = 7/4

v2 = 1.75 fps

MECHANICAL ENGINEERING: Design of Machine Elements - Rod with a circular cross-section

FS = S/Sa


Sa = F/A


A = pi/4 * d^2

A = 0.785 * d^2

A = pi * r^2

A = 3.14 * r^2


where:

FS = factor of safety

S = strength of the material

Sa = allowable stress

F = Force applied

A = cross-sectional area of material

r = radius of circular rod

d = diameter of circular rod


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1. Problem: Circular Rod

Determine the safe size of a circular rod to be loaded with an axial force of 3000 lbs considering a factor of safety of 4 and the material strength of the rod 30,000 psi.

find:

d = diameter of circular rod

given:

F = axial force = 3000 lbs

S = material strength = 30,000 psi

FS = factor of safety = 4


solution:

Sa = F/A

Sa = 3000/0.785 d^2 

Sa = 3821.66 d^2  ---> equation1


FS = S/Sa

4 = 30,000/Sa

Sa = 30,000/4

Sa = 7500  ---> equation2


equation2 in equation1

Sa = 3821.66 d^2

7500 = 3821.66 d^2

d^2 = 1.96

d = 1.4 in ---> use 1.5 in