2018-02-14
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1) A heat pump moves … from one place to another. 2) Sometimes a heat pump works better than heating with a... 3) Electric motors are used to set … work. 4) Sometimes an electric heater supplies … to heat pumps. 5) A refrigeration cycle uses … which moves through the tubes and carries the heat. 6) The refrigerant is forced to change from a gas to …
Exercise III. Translate the following conditional sentences into Russian using the rules:
| «0» условное: | - переводится настоящим временем. |
| «1» условное | - переводится будущим временем. |
| «2» условное | - переводится прошедшим временем с частицей «бы» |
| «3» условное | - переводится прошедшим временем с частицей «бы» |
1) If warm water is circulated through the pipes or tubes, the system is called a hot-water system. 2) If I were to choose an under-floor heating system, I would choose a warm water system for a bathroom and an electric system for a bedroom. 3) Every family would have installed an under-floor heating system if it wasn’t so expensive. 4) If we didn’t have refrigerators, we wouldn’t have been able to store fish and meat safely for long periods. 5) Natural ventilation will be possible if the spaces for ventilation are small. 6) This piping system would have had a 100 year’s lifespan if it had been made of reliable materials.
Exercise IV. Tasks to the text:
Prove that a refrigerator and an air-conditioner are both heat pumps.
Describe the principal stages of a refrigeration cycle.
Exercise V. Read the text quickly and say if the statements below are true or false. Correct the false statements.
Solar cells
A solar cell (солнечный элемент) or photovoltaic cell (фотоэлектрический преобразователь) is a device that converts light energy into electrical energy. Sometimes the term solar cell is used for devices intended specifically to take energy from sunlight, while the term (термин) photovoltaic cell is used when the light source is unspecified (не оговаривается).
Solar cells have many applications. They have long been used in situations where electrical power from the grid (электроэнергетическая система) is unavailable, such as in remote area power systems, Earth-orbiting satellites and space probes, consumer systems, e.g. handheld calculators or wrist watches, remote radiotelephones and water pumping equipment. More recently, they are starting to be used in assemblies of solar modules connected to the electricity grid through an inverter.
Solar cells are regarded as one of the key technologies towards a sustainable energy supply.
1) Both a solar cell and a photovoltaic cell use the energy of the Sun. 2) Solar cells have many applications, from Earth orbiting satellites to wrist watches. 3) Solar cells are very expensive and cannot be considered a reliable energy supply source.
Exercise VI. Give a short summary of the text.
UNIT VI
Exercise I. Check the pronunciation of the following words with the teacher:
Either, compartment, commercial, vapour, vaporise, evaporation, pressure, liquid, thermodynamic, absorption, source, compression, exit, superheat, efficient.
REFRIGERATION
Refrigerators work by the use of heat pumps operating in a refrigeration cycle. An industrial refrigerator is simply a refrigerator used in an industrial setting, usually in a restaurant or supermarket. They may consist of either a cooling compartment only (a larger refrigerator) or a freezing compartment only (a freezer) or contain both. The dual compartment was introduced commercially by General Electric in 1939.The vapour compression cycle is used in most household refrigerators. In this cycle, a circulating refrigerant such as Freon enters the compressor as a vapour at its boiling point. The vapour is compressed and exits the compressor as a superheated vapour. The superheated vapour travels through part of the condenser which removes the superheat by cooling the vapour. The vapour travels through the remainder of the condenser and is condensed into a liquid at its boiling point. The saturated liquid refrigerant passes through the expansion valve where its pressure abruptly decreases.
The decrease in pressure results in the flash evaporation and auto-refrigeration of a portion of the liquid, typically, less than half of the liquid flashes. The cold and partially vaporised refrigerant travels through the coil or tubes in the evaporator. There a fan circulates room air across the coil or tubes, and the refrigerant is totally vaporised, extracting heat from the air which is then returned to the food compartment. The refrigerant vapour returns to the compressor inlet to complete the thermodynamic cycle. An absorption refrigerator works differently from a compressor refrigerator, using a source of heat, and typically runs more quietly. The Peltier effect uses electricity directly to pump heat; refrigerators using this effect are sometimes used for camping, or where noise is not acceptable. They are totally silent, but less energy-efficient than other methods.
Notes to the text: Peltier effect – явление Пелтье, французского физика ((1785-1845), выделение или поглощение теплоты в месте контакта двух веществ (металлов или полупроводников) при прохождении через контакт электрического тока. При изменении направления тока эффект меняет знак.
Exercise I. Translate the following attributive groups into Russian:
Refrigeration cycle, vapour compression cycle, saturated liquid refrigerant, expansion valve work, refrigerant pressure decrease, liquid flash evaporation, room air circulation tubes, absorption refrigerator work, energy efficient method
Exercise II. Translate the sentences. Mind that:
either of - любой из; either … or – либо … либо; neither of – ни один из…, никакой; neither … nor – ни … ни.
1) Both commercial and home refrigerators are used to store foods. Neither of them was in use a hundred years ago. 2) Neither air conditioners nor heat pumps can operate at temperatures below 20°C. 3) Either climatic conditions or scarcity of energy resources or both can be a good reason for economy in heat energy production and distribution. 4) Either of the products of the Finnish Foreign Trade company is in high demand, so they decided to set up new branches abroad. 5) Heat can be removed through the process of radiation, convection and conduction using either water or air as mediums.
Exercise III. Translate the sentences into Russian. Mind: provide – обеспечивать, предусматривать, provided that – при условии, что…
1) Refrigerators provide a longer life span of meat. 2) Freezers keep foods frozen provided that the inside temperature is below the freezing point. 3) We canreduce emissions of CO² provided that more efficient energy than fossil fuels is used. 4) Today the necessary energy is provided mainly by burning fossil fuels. 5) Heated water circulates through the pipes provided that it is warmed by gas, oil or electricity. 6) Electric under-floor heating will warm a room provided that the floor is properly insulated.
Exercise IV. Translate the sentences into Russian paying attention to the Infinitive constructions:
1) A quality control system is believed to solve problems with the quality in mass production. 2) A new car that frequently breaks down is known in the United Kingdom as a “Friday car”. Such a car seems to be manufactured by careless workers who are thinking about the weekend. 3) Users want their household appliances to operate as long as possible. 4) In natural ventilation, the cool outside air is supposed to be drawn into the building naturally through openings. 5) Agricultural products have proved to be an efficient bio-fuel.
6) Central heating equipment requires maintenance and replacement to be done regularly. 7) We would like solar energy to become a global source of power, which is difficult due to local geographic variations in sun supply.
Exercise V. Complete the sentences choosing the correct form in brackets.
1) In a vapour compression cycle, the vapour is … and exits the compressor as a superheated vapour. (compressing, compressed) 2) The liquid … passes through the expansion valve and its pressure decreases. (refrigerant, refrigeration) 3) The … in pressure results in the flash evaporation. (decrease, increase) 4) The cold and partially vaporised refrigerant travels through the … in the evaporator. (compartment, tubes) 5) An … refrigerator uses electricity directly to pump heat. (absorption, compressor)
Exercise VI. Tasks to the text:
1) What is a dual compartment? 2)Describe a vapour compression cycle.
3) What is the difference between a compressor refrigerator and an absorption refrigerator? 4) What are their advantages and disadvantages?
Exercise VII. Read the text without a dictionary. What is the main idea of the text?
Refrigerator
Refrigerators are used to store foods which deteriorate at ambient (окружающий) temperatures. Devices described as "refrigerators" maintain a temperature a few degrees above the freezing point of water; similar devices which maintain temperatures below the freezing point of water are called "freezers". The refrigerator is a relatively modern invention; it replaced the common icebox (ледник) which had been a household item for almost 150 years before. Freezers keep their contents, usually foods, frozen. They are used both in households and in commercial enterprises. Most freezers operate at -18 °C.
Commercial fridge and freezer units were in use for almost 40 years prior to home models. They used toxic ammonia gas systems, making them unsafe for home use. Practical household refrigerators were introduced in the 1920s and gained wider acceptance in the United States in the 1930s as prices fell and non-toxic, non-flammable synthetic refrigerants such as Freon or R-12 were introduced. 60% of households in the US owned a refrigerator by the 1930s; the same figure was achieved in the UK only some 40 years later, in the 1970s.
What facts from the history of refrigerators did you learn?
UNIT VII
Exercise I. Make sure you pronounce the following words correctly:
Process, vessel, fluid, combustion, tube, turbine, source, surface, flue gas.
STEAM BOILERS
In all power plants, power generation process is based on the work of a boiler. A boiler is a vessel in which water or other fluid is heated under pressure. The fluid is then circulated out of the boiler for use in various processes or for heating applications. The source of heat in a boiler is combustion of such fuels as wood, coal, oil or natural gas. An essential function of a boiler is to produce an efficient flow of heat from the heat source to the feed water or steam. This heat flow is due to conduction from the hot gases and radiation from the flames. The simplest structure consists of one or more steel drums and boiler tubes. Steam boilers have become more complex with the development of power generation. As steam turbines need superheated steam, the steam boiler incorporates a superheater, which is a heat transfer surface, to form superheated steam from saturated steam. Waterwalls have been added to the unit. They are boiler tubes connected with the water circulation system. The theoretical limit to which flue-gas temperature may drop is the temperature of the saturated steam. With higher boiler steam pressures a further extension to the heating surface is made in the form of an economizer. Here, feed water, which is lower in temperature than boiler steam, is heated by the flue gases as they leave the boiler surface. The economizer also sets a limit to which the temperature of the flue gases may drop. Further surface in the form of an air heater can be used to reduce the flue-gas temperature by warming the air needed for combustion.
When elementary drums and tubes of the steam boiler are added to its design in the form of waterwalls, superheater, economizer, air preheater, and possibly other heating surfaces, we have the steam generating unit. In addition to the heating surface, the steam generating unit includes the furnace, combustion and draft equipment for controlling combustion and steam formation. Several accessories for safety and maintenance are also part of the complete unit.
There are two types of boilers in general use: the fire-tube and the water-tube boiler, with the latter predominating.
Exercise II. Translate the following attributive groups into Russian:
Power plant work, power generation process, steam boiler function, heat gas flow, water circulation system, steam generating unit, flue gas temperature, boiler steam pressure, heat recovery ventilation system, ventilation air excess moisture.
Exercise III. Match the words in A with the words in B:
a) steam, power, gas, steel, boiler, heating, draft, safety, water, feed
b) circulation, plant, drums, pressure, tubes, boiler, flow, surface, equipment, accessories.
Exercise IV. Complete the sentences according to the text:
1) The two general types of boilers are ….2) An essential function of a steam boiler is to produce …. 3) The simplest structure of a steam boiler includes …. 4) In an economiser, the feed water is heated by ….5) A further extension of the heating surface is made in the form of … or ….. 6) A steam generating unit consists of …..
Exercise V. Translate the sentences paying attention to the Participial construction. Find a sentence with one in the text.
1) Steam turbines are becoming more complex, boilers developing into complicated units. 2) A refrigerator is a relatively modern invention, a common icebox having been replaced some 150 years ago. 3) The evaporator operating at a temperature below dew point, moisture is collected at the evaporator section.
4) Open windows disrupting the work of the HVAC system, air-conditioned buildings often have sealed windows. 5) Ceiling fans are widely used in small spaces, with the air circulating within a room.
Exercise VI. Translate the following sentences into Russian. Mind that “ing-forms” can have different functions in a sentence.
1) In Roman hypocausts, the floors and walls were warmed up quickly, hot air from fires circulating through flues and ducts. 2) When a ceiling fan is in operation, the air is circulating within the room, hot air rising to the ceiling.
3) Hot water circulating in the pipes is an essential part of an under-floor heating system. 4) The circulating of the air in a natural ventilation system is provided by the stack effect. 5) Circulating through the boiler tubes the water absorbs heat.
Exercise VII. Tasks to the text:
1) What is the main function of a steam boiler? 2) What are the main types of boilers? 3) Describe the main units of a boiler and their functions.
Exercise VIII. Read the following text without a dictionary and give a short summary.
District heating
District heating is a system for distributing heat generated in a centralised location for residential and commercial space heating and water heating. The heat is obtained from a heat boiler station or cogeneration plant (combined heat and power) by burning fossil fuels but, more often, biomass; geothermal heating and central solar heating as well as nuclear power are also used. District heating plants or cogeneration plants can provide higher efficiency and better pollution control than local boiler stations. The difference between the two systems is that in a cogeneration plant, heat and electricity are generated simultaneously, and in a heat boiler station, only heat is generated.
After generation, the heat is distributed to the customer via a network of pipes. Usually the pipes are installed underground but there are also systems with overground pipes. The common medium for heat distribution is water or steam.
District heating has various advantages compared to individual heating systems. District heating is more energy efficient. The larger combustion units have a more advanced flue gas cleaning than single boiler systems. District heating systems use waste heat energy from industries and are environment friendly. But they require high financing. They are attractive only for areas with large buildings.
