Basic Refrigeration Cycles and Concepts.

In the artificial production of low temperatures ranging from the normal ambient-air temperature down to absolute zero, one or more refrigeration cycles or processes may be involved. For cooling in the temperature range down to -200 F, vapor-compression refrigeration using reciprocating, rotary, or centrifugal compressor may be used. Such systems are commonly used for the production of cold. For the production of extremely low temperatures down to absolute zero, irreversible or reversible adiabatic expansion of a gas, vaporization of a liquefied gas, or magnetic cooling may be used.

Although refrigeration is primarily an application of thermodynamics, many other phases of engineering are involved in the design, manufacture, application, and operation of refrigeration systems. Some knowledge of the chemistry of refrigerants is desirable in determining their reactions with metals and other materials with which they may come in contact. The thermodynamic properties of the refrigerants must be known before the cycle analyses can be made. A study of evaporators and condensers, those portions of the system used for the absorption and rejection of heat, respectively, involves the fields of heat transmission and fluid mechanics.

In addition, steady state and, in some cases, periodic and transient heat transfer are involved in the determination of cooling-load requirements. The calculation of cooling loads also requires a knowledge of psychrometry. Fluid mechanics forms the basis for the sizing of the lines through which the gaseous and liquid refrigerants must flow. The physical capacity of a compressor or expander will be determined from thermodynamic factors, but the physical design must also involve structural considerations.

The standard unit in the rating of refrigerating machines, condensing units, and other parts of a refrigerating system is the ton of refrigeration, defined as the removal of heat at the rate of 12,000 Btu per hour or 200Btu per minute. The ton-day of refrigeration, also sometimes used, is defined as the heat removed by a ton of refrigeration operating for one day, or 288,000 Btu. These somewhat ambiguous terms have their origin in the concept of the amount of heat absorbed by a ton of ice when melting from the solid to the liquid phase at 32 F. This derivation assumes a latent heat of ice of 144 Btu per pound, whereas it is actually slightly less than this. However, no error is introduced in the calculations, because the units are defined in terms of heat removal and no longer associated with the melting of a definite weight of ice.

Lesson B.

Translation Practice,

Exercise I. Parentheses. Вставні слова.

Read and remember:

although though by the way furthermore hence however in addition (to) obviously on the other hand respectively thus unfortunately whereas

— хоч, хоча — хоч, хоча — між тим — більш того — віднині, отже — однак — крім того, на додаток — очевидно — з іншого боку — відповідно — таким чином — на жаль — тоді як

Exercise II. Translate into Ukrainian:

1. Although there are many different nations in the world there are some things that are the same everywhere.

2. Obviously hydraulic turbine values are used for hydraulic turbines hydroelectric systems.

3. However, steel and alloy steels are required for the highest operating pressures such as 5000 psi and 1200 F steam.

4. In spite of four components, however, the heart of the vapor-compression system is the compressor.

5. On the other hand, all present-day methods for the large-scale use of molecular and nuclear energy are based on the evolution of energy as heat, and subsequent conversion of part of the heat into useful work.

6. Accordingly, the efficiency of all such processes is destined to be low (values greater than 30 percent are uncommon), despite improvements in the design of equipment.

7. A still further increase in specific speed is obtained with the propeller, or axial-flow pump. In this type there is no change in radius of a given streamline, and hence centrifugal action plays no part.

8. The use of water power involves the transformation of mechanical energy from one form to another; hence, 100 percent efficiency is theoretically possible.

9. Under SI Units, each physical quantity has only one particular unit for its measurement.

Thus, a length is only measured in meters.

Exercise III. Common and Decimal Fractions. Reading Rules:

1/2 — a half; one half

1/3 — a third; one third

1/4 — a quarter, one quarter, a fourth, one fourth

2/3 — two thirds

3/4 — three fourths

2 1/2 — two and a half

3 1/3 — three and a third

0.2 — 1) oh /ou/ point two

 

2) naught point two

3) zero point two

4) point two

5) nil point two

1.25 — one point two five

Exercise IV. Read the following numerals:

0.5; 2 1/4; 1.5; 1/2; 0.02; 23,000; 1/3; 3/4; 1 1/2; 0.567; 2,600,731; 4,000,000; 2,500; 0.7; Read telephone numbers: (e.g. 123-40-55 — one-two-three-four-oh-double five) 425-05-05; 322-33-44; 267-12-17; 222-89-90; 321-73-67; 722-52-52; 337-78-94; 566-81-10; 123-45-67.

Years and Dates. Remember the reading rules.

1) 7.1.98 (G.B.) — January the seventh, nineteen ninety-eight

1.7.98 (USA) — January seventh, nineteen ninety-eight

2) 15 June 1900 (G.B.) June the fifteenth, nineteen hundred

3) 16 February 1908 (USA) — February sixteenth, nineteen oh eight

4) 1 March 2000 — March the first, twenty hundred or: two thousand

5) 9 May 1945 — May the ninth, nineteen forty-five.

 

Exercise V Fill in the prepositions of time at, in, on

1) We shall graduate from the Academy … three years.

2) Students living in the hostel usually get up … six o’clock in the morning.

3) They agreed to meet … seven this evening.

4) The elections to the Parliament will be held … four years.

5) America was discovered … 1492.

6) The lectures and classes in the Academy begin … 8 o’clock.

7) The Day of Independence Americans celebrate … the 4-th of July,

8) The Constitution of Ukraine was adopted … June 28, 1996.

9) The Great Patriotic War started … 1941.

10) We celebrate the Victory Day … May, 9.

 

Exercise VI. Read the following sentences and translate them into Ukrainian

1. Ukraine declared its independence on 24 August 1991

2. The Second World War started in September 1939

3. The Curies shared the Nobel Prize for physics in 1903.

4. The first person flew into space on 12 April 1961.

5. J.I.Kennedy was killed on 22 November 1963.

6, Columbus reached America on 12 October 1492

7. Galileo Galilei was born in Italy in 1564.

Exercise VII. Answer the questions:

1) What is today's date? 2) What date was yesterday? 3) What is tomorrow's date? 4) What is

the date of your birth?

Translate the text:

ELEMENTARY VAPOR-COMPRESSION REFRIGERATION CYCLE WITH RECIPROCATING COMPRESSOR.

At atmospheric pressure, liquid ammonia evaporates at -28F (saturated temperature corresponding to 14.7 pounds per square inch absolute pressure or psia), and under these conditions one pound of liquid ammonia in changing into vapor absorbs 589.3 Btu (latent heat of evaporation). Thus the simplest form of a vapor refrigeration system consists of an open vessel containing a liquid refrigerant such as ammonia. The ammonia evaporates at temperatures below those surrounding the container and in so doing absorbs heat. However, such an uncontrolled refrigeration system is uneconomical, since the refrigerant is not recovered and the evaporating temperature is limited to that corresponding to the atmospheric pressure. Such systems are therefore never used commercially.

With proper auxiliary equipment, however, the refrigerant can be recovered and reused in a cyclic process; the temperature of evaporation of the refrigerant can be controlled by controlling the pressure. Thus if liquid ammonia is maintained at a pressure of 30.42 psia, the saturation or evaporating temperature is 0 F, and the latent heat of vaporization is 568.9 Btu per pound; if the absolute pressure is 59.74 psia, the evaporating temperature is 30 F, and the latent heat of vaporization is 544.8 Btu per pound.

 

Lesson C.

BUSINESS LETTERS

I. The right address	American
Mr. John Anderson Shipping Dept. Mind Workers Inc. or 908 West Park Avenue Rockford AL 61125 USA	Mind Workers Inc. 908 West Park Avenue Rockford AL61125 USA Attention Mr. John Anderson

	British
George Brown Esq., Export Sales Manager, Barton Industries Ltd. 55 London Rd., Boughton BN5 9 KL Great Britain	Ms Alison Freeman Marketing co-ordinator United Packaging Corp. 11 East Shore Drive Green Bay Wisconsin WI 53405 USA

II. The layout of letters

British:

The name of the sending firm (organization)

Your Ref: Our Ref:

Mr.James Green (or The Sales Manager)

Sales Manager

CCC& & Co. Ltd.

44 Park Sq.

London E6 6HG 23 December 199...

Dear Mr.Green, (or Dear Sir, Dear Sirs, Dear Jim, Dear Mrs.Brown, Dear Miss Grey) RE: Training of word processor operatives

Thank you for your letter of 17 December suggesting that we...

.................................................................................................

.................................................................................................

Please let me know if this is convenient. I look forward to hearing from you.

Best wishes (or Best regards)

Yours sincerely,

signature

Ms.Gillian Jones

Personnel Manager

American:

The name of the firm and its address

Date: September 12, 199..

John L. Davis, President

Autocomp. Inc.

3100 South Jackson Street

Detroit, MI 48220

USA or

Messrs. Brown & Smith, Inc.

220 Lincoln Street,

Chicago, Illinois

USA

 

Dear Mr.Davis:

(or Gentlemen:)

(Attention: Mr.John Brown)

RE: Order 230 (or Subject No. 230)

We recently purchased 250,000 of automated material-handling equipment from your company.

We look forward to doing business with your company in the future.

Sincerely,

(or Yours very truly, Yours faithfully)

Victor Bond

signature

Plant Manager

Abbreviations:

1. RE: (Latin: in re) — відносно

2. Per pro (Latin: per procurationem) — за умовленістю, від імені

3. #24 (USA) No.24 (GB)

4. P.T.O. — please turn over — будь ласка, перегорніть сторінку

5. do.(ditto) — стільки ж

6. Ltd. — Limited (in Britain) — товариство з обмеженою відповідальністю

7. Bros. & Co. — брати та компанія

8. Corp. (in the USA) — Corporation — корпорація

9. Stock Corporation — акціонерна корпорація

Inc. — Incorporated — зареєстрований як корпорація

9. Messrs. — from French "Messieurs" — " панове "

10. Ms. — скороч. звернення до ділової жінки

11. Esq. використовується в адресах після призвіщ осіб, займаючи вагомий суспільний стан

12. с/о — care of, the letter goes — до уваги, лист до

Attn.: — увага, до

P.O.В. — абонентська скринька

13. enc. or encl. — enclosed — до листа додається

14. asap. — as soon as possible.

15. viz. — а саме

Exercises:

I. Write addresses according to the British and American standards.

II. Write business letters of British and American style.

 

UNIT 3

Lesson A. Text: Elementary Absorption Refrigeration Cycle.

Grammar. The Gerund. Forms and Functions.

Lesson B. Translation Practice. Comparative Constructions. Meanings of the words

more, much more; because, because of. Text for translation: The Vapor Absorption

System.

Lesson C. Speech Practice. This is the USA.

Lesson A.

Key words: absorb /əb'sɔ:b/ всмоктувати; поглинати

replace /ri'pleis/ замінювати

absorber /əb'sɔ:bə/ абсорбер

operate /'ɔpereit/ діяти; управляти; керувати

essentially /i'senʃəli/ по суті

in addition to до того ж, крім того

transfer /træns'fə:/ переносити, передавати

generator /'ʒenəreitə/ генератор

drive off /draiv of/ відводити, витягати

weak /wi:k/ слабкий

coil /'kɔil/ змійовик

insulated space /,insju'leitid speis/ ізольований простір

alcohol /'ælkəhɔl/ спирт

ether /'i:θə/ ефір

supply /sə'plai/ постачати; доставляти; заміняти

flow /'flou/ потік

improvement /im'pru:vmənt/ поліпшення, удосконалення

extend /iks'tend/ розширювати, поширювати,

продовжувати

circuit /'sə:kit/ контур; ланцюг; схема

solution /sə'lu:ʃn/ розчин; вирішення, розв’язання

gravity /'greiviti/ сила ваги; тяжіння

pump /'pʌmp/ насос

slug /'slʌg/ слаг (технічна одиниця маси в

англійській системі мір)

seal /si:l/ печатка, пломба; щільно

закривати, герметизувати

discharge /dis'tʃa:ʒ/ випускати; розвантажувати

heat exchanger /'hi:t iks'tSeinʒə/ теплообмінник

analyzer /'ænələizə/ аналізатор

 

 

Lexical Drills

Exercise I. Read the words with the same root. Underline the suffixes. Define the part of speech. Translate the words into Ukrainian:

to absorb — absorber — absorbent,

to add — addition — additional,

to evaporate — evaporator — evaporation,

to refrigerate — refrigerator — refrigeration

— refrigerating —refrigerant,

to rely — reliable — reliability

Exercise II. Find in the text "Elementary Absorption Refrigeration Cycle" terms consisting of one word, two words and three words. Translate them into Ukrainian.

e.g. I II III

refrigerant absorbing absorption refrigeration

chamber cycle

Exercise III. Translate these word-combination into English:

1. холодильний агент

2. механічне охолодження

3. штучне охолодження

4. металообробна промисловість

5. товарний склад

6. менш однієї кінської сили; частковий

7. переробка харчових продуктів

8. кондиціювання повітря

Grammar

The Gerund. Forms and Functions.

Герундій. Форми і функції

Forms

Active Voice Passive Voice

Indefinite Gerund cooling — охолодження, being cooled — охолоджувати,

охолоджувати при охолодженні

Perfect Gerund having cooled — після having been cooled — після того, як

охолодження, охолодивши був охолоджений; як тільки був

охолоджений

Functions Функції

1) subject (підмет) Heating the substance up was necessary in this case. У цьому випадку було необхідно нагріти речовину.

2) predicative (частина присудка) в сполученні з дієсловом to be, переводиться окремо від to be One of the effects of heat is turning a solid into liquid. Однією з дій тепла є перетворення твердої субстанції у рідину.

3) object (додаток) Thank you for coming (prepositional object). Дякую за те, що ви прийшли.

The guests enjoyed listening to the hostess playing the piano (direct object). Гості насолоджувались, слухаючи, як господиня грає на піаніно.

4) attribute (означення) The smoking room is in the end of the corridor. Кімната для паління знаходиться у кінці коридору.

A boiling point — точка кипіння; the idea of utilizing — ідея використання.

5) adverbial modifier (обставини) In designing the device new materials were used. При проектуванні пристрою були використані нові матеріали.

On reaching 100°С... При досягненні температури у 100°С... By creating... При створенні...

After (before) compressing gas... Після (до) стискання газу... Without preheating... Без запобіжного нагріву.

Note: Форми герундія збігаються з відповідними формами Present Participle і Perfect Participle. Але на відміну від дієприкметника;

1) герундій може мати перед собою прийменник тоді як перед дієприкметником може стояти тільки сполучник;

2) герундій може виконувати функції підмета і додатка, які дієприкметник не виконує;

3) перед герундієм у герундіальному звороті стоїть присвійний займенник або іменник у присвійному відмінку, а перед дієприкметником, у дієприкметниковому звороті, стоїть займенник в об'єктному відмінку або іменник у називному відмінку;

4) герундій використовується після наступних дієслів з прийменниками та словосполучень:

to succeed in — мами успіх;

to insist on — наполягати;

to be surprised at — дивуватися;

to be responsible for — відповідати (за);

to prevent from — запобігати;

to consist in — полягати (у);

to result in — призводити (до);

to be interested in — цікавитися;

to approve of — схвалювати;

to be fond of — лютити;

to be proud of — пишатися;

to depend on — залежати (від);

to object to — заперечувати;

to get used to — призвичаїтися (до).

Exercises

I. Give all possible forms of the Gerund. Translate them into Ukrainian.

to absorb, to develop, to evaporate, to mix, to melt, to burn, to sell, to solve, to turn, to improve, to fall, to increase, to freeze, to leave, to keep, to send, to run, to sink, to teach, to read.

 

II. Define the forms and functions of the gerund. Translate the sentences in Ukrainian:

1. Our professors like inviting young specialists to take part in research.

2. Much effort is being given to find the most efficient means of generating electricity.

3. Heating the gas increases the speed of the molecules.

4. We heard of our lecturer leaving for the international conference.

5. The investigator mentioned of having tested this material for strength.

6. Using atomic fuel for production of electricity is one of the most promising sources.

7. The range of measurement is limited between the boiling and freezing points of the liquid in use.

8. We insist on their taking part in this experiment.

9. After having checked the temperature twice he decided to change conditions of the experiment.

10.For measuring the atmospheric pressure a barometer is used.

11.Refrigerators are used for cooling foodstuff.

12.Most people like learning foreign languages.

13.Speaking foreign languages is of great importance in our age of great migrations.

14.Science requires experimenting and accurate calculating.

15.The boiling point of a liquid is the temperature at which the liquid boils.

16.At being cooled a body loses its heat.

17.After compressing gas tends to expanding.

18.On reaching 100°C water boils.

19.The idea of utilizing fire for warming houses appeared long ago.

20.By creating new projects of warming systems scientists use laws of thermodynamics.