Expansion Methods Assignment

Introduction to Technical Writing Reading

Reading Based Expanded Definitions – District Heating

District Heating

District heating is perhaps the best solution for distributing heat for residential and commercial heating requirements. It involves the generation and distribution of heat, or thermal energy, at the community level rather than on a building-specific basis. In other words, instead of having on-site infrastructure, cumbersome boilers, and costly maintenance concerns, buildings are able to connect to an external network that delivers reliable heating and cooling. Not only does District Heating offer excellent opportunities for reducing environmental pollution, but it also helps to save energy. It is an extremely flexible technology, and can make use of any fuel.

District heating traces its roots to the hot water-heated baths and greenhouses of the ancient Roman Empire. These systems gained prominence in Europe during the Middle Ages and Renaissance, with one system in France in continuous operation since the 14th century. Although these and numerous other systems have operated in Europe over the centuries, the first commercially successful district heating system in North America wasn’t launched until 1877. American hydraulic engineer Birdsill Holly launched a district heating system in Lockport, New York.

Although the technology has matured over the centuries, it still relies on an old system of resource sharing. The heat is generated centrally. Great vats of water are heated in a power plant, and although these plants often burn fossil fuels, geothermal heating, central solar heating, and nuclear power are also being used. The heat travels via hot water or steam and is distributed to the customers via a network of pipes that circulate right into the structures being heated. District heating systems thus provide significantly higher efficiencies and better pollution control than localized boilers.

After the water is heated to near-boiling, it is fed into a network of pipes, a system of feed lines and return lines. The feed pipes take the heated water from the power station to the geographic area or district being heated. Generally, the pipes are installed underground, under the roads and sidewalks. Smaller offshoot pipes, fitted into these feed pipes, take the water directly into the individual dwellings. At the customer level, each residence is connected to the district heating network by heat exchangers, devices that transfer the heat from the water in the pipes into the structure’s individual boiler. When the heat has been transferred, the water passes into a return line, and is taken into the power plant and reheated. Thus the district heating supply water circulates endlessly in a closed pipeline.

The common medium used for heat distribution is water, but steam can also be also used. The advantage of steam is that in addition to heating purposes, it can be used in industrial processes due to its higher temperature. The disadvantage of steam is a higher heat loss due to the high temperature.

The system is efficient and robust. Very little heat is lost in transit. The pipes consist of steel piping, an insulation layer and an outer casing. Minor power outages have little to no effect on the large District Heating system; however, even short outages can cause individual boilers to fail.

District heating is a system that works. In Denmark, district heating covers more than 60% of space heating and water heating. In Finland, district heating accounts for about 50 per cent of the total heating market. Over 90 per cent of apartment blocks, more than half of all terraced houses, and the bulk of public buildings and business premises, are connected to a district heating network.

Benefits to the communities served by district heating have included avoided costs of energy, and reduced investment in individual household or building heating equipment. However, District heating is a long-term commitment that fits poorly with a focus on short-term returns on investment. The systems are expensive to install.

Abridged from the articles below:

•  District Heating, retrieved February 2009, from Wikipedia.org, http://en.wikipedia.org/wiki/District_heating
• Enwave District Hearting, retrieved October 2009 from Enwave.com, http://www.enwave.com/heating.php

Expansion Methods Assignment

Step 1: Read the article.

Step 3: OutlineStep 2: Draw a picture of a [insert topic of article]  

Parts Analysis Outline

Determine the parts involved in a [insert topic of article].

Tips

• Choose an order of description (front to back; outside to inside; north to south).
• Explain how these parts fit together in space.
• Describe the physical characteristics of the parts themselves.
• Avoid explaining how the parts function.

 Parts Analysis Paragraph

Write a Parts Analysis paragraph.

Tip

• Begin by writing a topic sentence.

Operating Principles Outline

Write an outline of the steps.

Tips

• Start by listing the steps in chronological order.
• Double check to ensure that that the steps are written on logical order and that no steps are missing.

Operating Principles Paragraph

Write an Operating Principles paragraph.

Tip

• Use “time” transition words to guide the reader through the sequence.