Air conditioning anf health

Air conditioning has no greater influence on health than heating, although poorly maintained air-conditioning systems (especially large, centralised systems) can occasionally promote the growth and spread of micro organisms, such as Legionella pneumophila, the infectious agent responsible for Legionnaire's disease (болезнь легионеров). On the contrary, air conditioning (including filtration, humidification, cooling, disinfection, etc.) can be used to provide a clean, safe, hypoallergenic atmosphere in hospital operating rooms and other environments where an appropriate atmosphere is critical to patient safety and well-being. Air conditioning can have a positive effect on people who suffer from allergies and asthma.

In serious heat waves, (период сильной жары) air conditioning can save the lives of the elderly. Some local authorities even set up public cooling centres for the benefit of those without air conditioning at home.

Air conditioning systems can generate sound levels which contribute to the loss of hearing if exposures are endured for a long time. These levels are similar to those of a busy highway or airport.

Exercise IX. Task to the text:

List the advantages and disadvantages of modern air conditioning. Give some more examples if you know them.

UNIT V

Exercise I. Make sure you pronounce the following words correctly:

Thermodynamics, energy, supply, refrigeration, refrigerant, cycle, fluid, liquid, surround, machine.

Exercise II. Give the Russian equivalents of the following words and word combinations:

Heat pump, extra energy, to move the heat, to provide energy, electric heater, to gain heat energy, cooling side, heating side.

Heat pump

A heat pump is a machine that moves heat from one place to another. A refrigerator is a heat pump because it moves heat from the inside to the outside and keeps the food inside cold, so it won't spoil. An air-conditioner is a heat pump, as it moves heat from the inside of a building to the outside

Some buildings are heated with heat pumps. In winter, a heat pump moves heat from the outside to the inside. Sometimes this works better than heating with a radiator. Usually, heat flows from a hot place to a cold place, according to the second law of thermodynamics. Heat will not move from a cold place to a warmer place by itself. Because of this, a heat pump must use extra energy to move the heat. Most heat pumps use electric motors to provide energy. Some heat pumps use heat energy, supplied by a flame or an electric heater.

Most heat pumps use a refrigeration cycle. A refrigeration cycle uses a fluid (a refrigerant) which moves through tubes and carries the heat. During the refrigeration cycle, the refrigerant changes from a liquid to a gas and back to a liquid. When it changes from a liquid to a gas, it gains (absorbs) heat energy.

The heat pump is set up so that the refrigerant gains heat from one place that will be cooled, and moves it to another place that will be warmed.

When a heat pump forces the refrigerant to change from a gas to a liquid it uses a compressor to do this. Often, an electric motor drives the compressor. The compressor compresses the refrigerant, and it changes from a gas to a liquid.

At the other end of the cycle, the refrigerant boils again. It changes from a liquid to a gas. But it needs heat to do this. When it takes up heat from its surroundings, it cools them down. So, where the refrigerant is changing from a liquid to a gas, it feels cooler.

This is the complete cycle, from the cooling side to the heating side. If the cooling side is the inside of a refrigerator, it gets cold. If the cooling side is the inside of a building, and the warming side is the outside of the building, the inside of the building gets cold. This is how an air-conditioner works.

Exercise II. Translate the following attributive groups into Russian:

A refrigeration cycle, a heat pump refrigeration cycle, heat pump refrigeration cycle stages; heat energy, heat energy absorption, refrigeration cycle heat energy absorption; an electric heater, an electric heater operation, electric heater operation problems, electric heater energy supply.

Exercise II. Complete the sentences with the words from the list below according to the text:

radiator, heat, energy, heat pumps, a fluid, a liquid.

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:

1) Prove that a refrigerator and an air-conditioner are both heat pumps.

2) 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 can reduce 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?