Refrigeration, Computers, Friction, Sustainability, and Piper Alpha
Refrigeration and Air Conditioning History
Before engineers learned how to cool air, life was very different. Food had to be bought the same day it was used. Most foodstuffs couldn’t be transported long distances, so people had to live close to the source of food. The inventor of refrigeration was Jacob Perkins. He was American, but he lived most of his life in Britain. He invented a machine for cutting and heading nails, and he was the first person to use steel to make plates for engraving banknotes.
In 1834, Perkins obtained a patent for a vapor compression system of cooling. Perkins often doesn’t get the credit for his important invention because he didn’t develop it. This was done by James Harrison. He showed his design at the International Exhibition of 1862 in London.
The work of Perkins and Harrison didn’t directly lead to the cooling of rooms. That honor belongs to an American called Willis Carrier. After cooling machines, Carrier moved on to rooms. He designed an apparatus to cool air using water sprays. In 1992, Carrier built his first true air-conditioning machine. The new invention spread quickly through the United States and then the world.
Mechanisms for cooling air have had a profound effect on human life all over the world. With cooled air, we can chill or freeze food to store it or to transport it long distances. We can keep medical supplies in good condition. Finally, we can cool factories, offices, homes, and cars to make them habitable even in the highest ambient temperatures.
Computer-Integrated Manufacturing (CIM)
Microprocessors have been part of the manufacturing process since the 1960s. More and more computers entered manufacturing, but only as aids, not as an integral part of the system. This was sometimes called CAM (Computer-Assisted Manufacturing). The overall process doesn’t change, but certain steps are computerized.
By the end of the 20th century, a totally new and more efficient approach had become possible: CIM (Computer-Integrated Manufacturing). CIM interlinks technologies to create the best manufacturing environment, from order to delivery. However, CIM requires all software and hardware to be compatible, able to communicate with each other. Many companies, therefore, are unable to use CIM. With the alternative, CAM, every step may be computerized, but each is a discrete process.
CIM is very different from CAM. Let us compare CIM and CAM in just one step: the interface between design and engineering. A customer’s specification may require a non-standard component or a process that the company doesn’t have. If the designer applies that specification in a CAM environment, the engineering department must order special components and processes to follow the design. With CIM, such problems are avoided. Instead of a linear manufacturing process, integrated manufacturing involves all the enabling technologies revolving around the CIM database, with processes interacting all the time. If engineering asks for components to be CAMmed in a certain order, CIM prompts that the machine is occupied with another job at that time. If CAT (Computer-Aided Testing) finds a problem in the first batch, this data is immediately fed out to all the enabling technologies so that it can be promptly rectified.
CIM is clearly the future. However, companies can only introduce CIM to new factories and will continue to rely on CAM in existing facilities.
Understanding Friction in Engineering
When two objects are in contact and one object is moved past the other, a force is created which resists the movement of the objects: it is called friction. Friction occurs in all machines and is usually considered detrimental to the machine’s efficiency.
In many mechanical design specifications, engineers must bear in mind several principles of friction. These are, specifically:
- Friction is a force that opposes movement between two objects.
- There is always some friction when two touching objects move relative to one another.
- To initiate movement from a standstill.
- Generally speaking, the smoother the surfaces, the lower the friction.
- Friction can be reduced by lubrication and by good design.
If friction is not taken into account by engineers beginning work on a design, the results are both costly and damaging. In order to reduce friction, the surfaces that are in contact need to be made smoother. In addition to machining, this can be done in two ways. Firstly, a lubricant can be added to reduce the coefficient of friction and so minimize wear and heat. There are many types of lubricants: thick or thin oil; powders, like talc; solids, such as graphite; and even acoustic lubrication. Secondly, the components can be designed so that friction is minimal.
Many examples of components that are affected by friction can be found inside an internal combustion engine. The pistons require lubrication because they slide up and down inside the cylinders. The lubrication system also provides oil to the moving parts of the engine. Before being pumped to the relevant parts of the engine, however, oil must be passed through a filter in order to remove dirt which would otherwise create friction and cause wear to components.
Engineering a Sustainable Future
Sustainable development is one of the biggest challenges facing engineers in the 21st century. Currently, industrial and economic development rely on the use of resources which will not last forever, and whose consumption may threaten the future of the planet. Usually, engineers are driven by (short-term) economics at the expense of other factors. This is short-sighted.
Engineering has played a big part in the way that energy has been produced and used. It is now widely recognized that (human-induced) greenhouse gas emissions, mainly due to the combustion of fossilized hydrocarbons, are changing the composition of the atmosphere in such a way that the Earth’s average global temperature will increase.
The urgent challenges of sustainable energy production and use need to be met by engineers. Firstly, energy demands need to be reduced to an absolute minimum. Another area where engineers have an important role is in the way that materials are used. A final area where there is huge scope for engineering creativity is in water and sanitation, which is sometimes abbreviated to ‘WATSAN’. It was engineers who constructed the water supply and sewerage systems that enabled London to be significantly cleaner and less disease-ridden.
In summary, the situation on our planet is currently unsustainable. Human beings are ‘living on the capital rather than the interest’. A range of urgent changes is required if the effects of catastrophic climate change, over-use of resources, and widespread pollution are to be avoided. Engineering has a key role to play in many areas, including energy, materials, waste, and water and sanitation.
The Piper Alpha Disaster
Piper Alpha was a gas rig, located in the North Sea off the coast of Scotland, designed to bring natural gas up from under the sea. Natural gas from underground wells is compressed at all times. Loss of compression for a few minutes would cause serious damage to a rig, so, to fail-safe, there are two compressors: A and B. On that day, compressor ‘A’ was shut down to remove a pressure release valve for maintenance, and the tube was temporarily sealed, several meters above the sight-line.
Then compressor ‘B’ failed, so the manager, with only a few minutes to make a decision, had to decide if compressor ‘A’ could be used. He did not have the report about the valve in compressor ‘A’ because it was wrongly filed, so he assumed that all was safe and compressor ‘A’ was activated.
There were other factors that aggravated the disaster. Divers were working under the rig. In addition, the control room was immediately above the first explosion. Consequently, the managers who could have organized an evacuation were killed first.
The public inquiry and 1990 report on the incident, led by Lord Cullen, has become a benchmark for safety on offshore facilities. Among the conclusions, the report highlighted two major failings in safety procedures:
- First, the system for recording maintenance work failed. Without knowledge of the repair to compressor ‘A’, the manager decided to reactivate it, which proved to be fatal.
- Secondly, the design of the rig also led to safety problems. The firewalls were inadequate and the control room was badly located.
The incident was an example of how a chain of incompetence, bad management, disorganization, unlucky coincidences, and bad decisions led to a catastrophe.