Fill in the gaps with derivatives of the given words.

Date: 2015-10-07; view: 472.

PART 1

REVIEW________________________________Check Yourself

FOLLOW UP

79. Read the texts of Unit 2 again and make notes under the following headings. Then use your notes to talk about Heating.

1) People's first attempts to create artificial heating.

2) The ways heat can be transferred.

3) Local heating systems.

4) Central heating systems. Basic types.

5) Components of central heating system.

6) 3 basic arrangements for the pipework and main principles of their work.

BOILER, a vessel in which water or other liquid is heated to the boiling point; specifically, the apparatus by which steam is produced from water, as one step in the process whereby the potential energy of coal or other fuel is converted into 1) … work by means of the steam-engine. Boilers of the latter kind must all possess 2) … essential features, whilst of other qualities that are 3) …some may not be altogether compatible with the special conditions under which the boilers are to be worked. Amongst the essentials are a receptacle capable of containing the water and the steam produced by its evaporation, and strong enough continuously to withstand with 4) …the highest pressure of steam for which the boiler is intended. Another essential is a furnace for burning the fuel, and a further one is the 5) …of a sufficiency of heating surface for the 6) …of the heat produced by the combustion of the fuel to the water which is required to be evaporated. Desirable qualities are that the 7) …of the furnaces should be such that a reasonably perfect combustion of the fuel should be possible, and that the heating surfaces should be capable of transmitting a large proportion of the heat produced to the water so as to obtain a high 8) …efficiency. Further, the design generally should be compact, not too heavy or costly, and such that the cleaning necessary tomaintain the evaporative efficiency can be easily effected. It should also be such that the cost of upkeep will be small, and that only an average amount of skill and attention will be 9) …under working conditions. It is for providing these qualities in different degrees according to the special requirements of various circumstances that the very different designs of the various types of boilers have been evolved.