Сomponents corresponding to the condenser and evaporator in a vapor compression cycle are the hot and cold gas-to-gas heat exchangers in gas cycles.

7) The working fluid does not receive and reject heat at constant temperature.

8) Because of their lower efficiency and larger bulk, air cycle coolers are not often used nowadays in terrestrial cooling devices.

 

XI. Fill in the blanks with appropriate words:

 

1) А circulating refrigerant such as Freon enters … as ….

2) Тhe condenser cools and removes ….

3) Тhe … refrigerant goes through the … valve.

4) The … mixture travels through the … coil.

5) The … cycle uses water-ammonia systems.

6) In the absorption system the … is replaced by an absorber, … and a generator.

7) The gas cycle works on the … cycle.

8) In the … cycle the refrigeration effect is equal to the product of ….

9) The … machine is very common on gas turbine-powered 'jet' ….

10) In the early years of the twentieth century … cycle was popular and widely used.

 

XII. Translate into English using the active vocabulary:

 

1. Парокомпрессионный цикл используют во многих системах охлаждения на торговых и промышленных предприятиях.

2. Перегретый пар проходит через конденсатор.

3. В регулирующем вентиле давление жидкого холодильного агента уменьшается.

4. У цикла паропоглащения низкий коэффициент полезного действия.

5. Абсорбер растворяет охладитель в подходящей жидкости.

6. В абсорбционном холодильнике используется подходящая комбинация охладителя и абсорбента, например: аммиак (охладитель) и вода (абсорбент).

7. Когда рабочей жидкостью является газ, тогда холодильный цикл называют газовым.

8. В газовом цикле не используются процессы конденсации и испарения.

9. Газовый цикл менее эффективен, чем парокомпрессионный.

10. Устройства охлаждения и вентиляции реактивных самолетов также служат цели герметизации самолета.

 

XIII. Answer the questions:

 

1. What cyclic refrigeration is used in industrial refrigeration systems?

2. Is the vapor-compression cycle or the vapor absorption cycle popular now? Why?

3. What refrigerant is used in the vapor-compression cycle / vapor absorption cycle / gas cycle?

4. What are the main components of a typical vapor-compression refrigeration system?

5. What happens with vapor in the compressor?

6. How does the condenser work?

7. What is the cause of flash evaporation?

8. How is the cold vapor-liquid mixture vaporized?

9. How is the thermodynamic cycle completed?

10. What is the coefficient of performance in the vapor absorption cycle?

11. Where is the vapor absorption cycle used?

12. What is the compressor replaced by in the vapor absorption cycle?

13. What is the most common combination of refrigerant and absorbent?

14. What components are there in the gas cycle?

15. Why is the gas cycle less efficient than the vapor compression cycle?

16. What can you say about air cycle coolers?

17. What other alternatives to the vapor-compression cycle are there?

 

XIV. Skim through the text and say in a few sentences what the message of the text is. Answer the questions which follow.

 

Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). The degree Celsius (symbol: °C) can refer to a specific temperature on the Celsius scale as well as serve as unit increment to indicate a temperature interval (a difference between two temperatures or an uncertainty). “Celsius” is named after the Swedish astronomer Anders Celsius (1701 – 1744), who developed a similar temperature scale two years before his death.

Until 1954, 0 °C on the Celsius scale was defined as the melting point of ice and 100 °C was defined as the boiling point of water under a pressure of one standard atmosphere; this close equivalency is taught in schools today. However, the unit “degree Celsius” and the Celsius scale are currently, by international agreement, defined by two different points: absolute zero, and the triple point of specially prepared water. This definition also precisely relates the Celsius scale to the Kelvin scale, which is the SI base unit of temperature (symbol: K). Absolute zero—the temperature at which nothing could be colder and no heat energy remains in a substance—is defined as being precisely 0 K and −273.15 °C. The triple point of water is defined as being precisely 273.16 K and 0.01 °C.

This definition fixes the magnitude of both the degree Celsius and the unit kelvin as being precisely 1 part in 273.16 parts the difference between absolute zero and the triple point of water. Thus, it sets the magnitude of one degree Celsius and the kelvin to be exactly equivalent. Additionally, it establishes the difference between the two scales’ null points as being precisely 273.15 degrees Celsius (−273.15 °C = 0 K and 0.01 °C = 273.16 K).

Some key temperatures relating the Celsius scale to other temperature scales are shown in the table below.

	Kelvin	Celsius	Fahrenheit
Absolute zero (precisely, by definition)	0 K	−273.15 °C	−459.67 °F
Melting point of ice (approximate)	273.15 K	0 °C	32 °F
Water’s triple point (precisely, by definition)	273.16 K	0.01 °C	32.018 °F
Water's boiling point (approximate)	373.1339 K	99.9839 °C	211.9710 °F

Throughout the world, except in the U.S. and perhaps a few other countries the Celsius temperature scale is used for practically all purposes. The only exceptions are some specialist fields (e.g., low-temperature physics, astrophysics, light temperature in photography) where the closely related Kelvin scale dominates instead. Even in the U.S., almost the entire scientific world and most engineering fields, especially high-tech ones, use the Celsius scale. The general U.S. population (not considering foreign immigrants), however, remains more accustomed to the Fahrenheit scale, which is therefore the scale that most U.S. broadcasters use in weather forecasts. The Fahrenheit scale is also commonly used in the U.S. for body temperatures. The United Kingdom has almost exclusively used the Celsius scale since the 1970s, with the notable exception that some broadcasters and publications still quote Fahrenheit air temperatures in weather forecasts (especially during summer), for the benefit of generations born before about 1950, and air-temperature thermometers sold still show both scales for the same reason.

 

* * *

1. What does the degree Celsius serve?

2. What define the unit “degree Celsius” and the Celsius scale?

3. What is absolute zero?

4. What is the definition between the degree Celsius and the unit kelvin?

5. Where is the Celsius temperature scale used?

 

XIV. Skim through the text and say in a few sentences what the message of the text is. Ask some questions to your partner.

 

[Show more]

[Show more]

Fahrenheit is a temperature scale named after the German-Dutch physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724.

In this scale, the melting point of water is 32 degrees Fahrenheit (written “32 °F”), and the boiling point is 212 degrees, placing the boiling and melting points of water exactly 180 degrees apart. On the Celsius scale, the melting and boiling points of water are exactly 100 degrees apart, thus the unit of this scale, a degree Fahrenheit, is ⁵⁄₉ of a degree Celsius. The Fahrenheit scale coincides with the Celsius scale at -40 °F, which is the same temperature as -40 °C.

Absolute zero is −459.67 °F. The Rankine temperature scale was invented to use degrees the same size as Fahrenheit degrees, so 0 °R would be absolute zero, namely −459.67 °F.

The Fahrenheit scale was the primary temperature standard for climatic, industrial and medical purposes in most English-speaking countries until the 1960s. In the late 1960s and 1970s, the Celsius (formerly Centigrade) scale was phased in by governments as part of the standardizing process of metrication. In the United States and perhaps a few other countries (such as Belize) the Fahrenheit system continues to be the accepted standard for non-scientific use. Most other countries have adopted Celsius as the primary scale in all use. Fahrenheit is sometimes used by older generations in English speaking countries, especially for measurement of higher temperatures.

 

 

 

 

UNIT 3

I. Read and translate the text:

Icebox

An Icebox was the common appliance for providing refrigeration in the home before safe refrigerants made compact mechanical refrigerators useful.

Commonly iceboxes were made of wood, most probably for ease of construction, insulation, and aesthetics: many were handsome pieces of furniture.

Iceboxes had hollow walls that were lined with tin or zinc and packed with various insulating materials such as cork, sawdust, straw or seaweed. A large block of ice was held in a tray or compartment near the top of the box. Cold air circulated down and around storage compartments in the lower section. Some finer models had spigots for draining ice water from a catch pan or holding tank. In cheaper models a drip pan was placed under the box and had to be emptied at least daily.

Iceboxes date back to the days of ice harvesting which in a growing America had hit an industrial high that ran from the mid-19th century to the 1930s when the refrigerator was introduced into the home. Most municipally-consumed ice was harvested in winter from snow-packed areas or frozen lakes. Even Thoreau's Walden Pond was not spared from ice harvesting. The ice was stored in ice houses, or shipped as far as India by Frederic Tudor, the "Ice King".

With metropolitan growth many of the sources of natural ice became contaminated from industrial pollution or sewer runoff. As early mechanical refrigerators became available, they were installed as large industrial plants producing ice for home delivery. Able to produce clean, sanitary ice year-round, their product gradually replaced ice harvested from ponds.

With wide-spread electrification and safer refrigerants, mechanical refrigeration in the home became possible. With the development of the chlorofluorocarbons (along with the succeeding hydrochlorofluorocarbons and hydrofluorocarbons), that came to replace the use of toxic ammonia gas, the refrigerator replaced the icebox. However, because of the prevalence of the icebox in recent human history, the name "icebox" is still used colloquially for the modern home refrigerator by older Americans in some regions.

The horse-drawn ice wagon and the daily occupation of the iceman, who made regular door-to-door deliveries of block ice for iceboxes, was as much a social institution as the milk man.

Apartment buildings had small doors that opened to the ice box from the back porch. The ice man would bring the block of ice and insert it into the ice box through this door. Ice was delivered on a regular basis to these buildings and the people would pay for the ice. Children would go on the ice wagon and take chips of fallen ice as treats during the summer.

 

Words to the text: