Английский язык для обучающихся по направлению «Криогеника и нефтехимическое производство». Учебное пособие

SECTION II

Cooling with Solid Cryogens

Grammar: Participle I as adverbial modifier of action.

Word-formation: Suffix -ing.

Speaking: Operating and controlling units working with solid criogens.

Learn the pronunciation and the meaning of the words:

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Grammar study:

Participle I in the function of adverbial modifier of action

Одной из функций причастия настоящего времени является обстоятельство образа действия, отвечающее на вопрос “как”, “каким образом”. Причастие первое в данной функции переводится на русский язык деепричастием.

Samples: Specialists in cryogenic area attain more stable temperature control, using solid cryogens – Специалисты в области криогеники получают более стабильный контроль за температурой, используя твердые криогены.

Vocabulary development: word-formаtion: suffix -ing (See section I)

Exercise 1. Translate the sentences with Participle I in the functions of adverbial modifier of action and an attribute:

1.Solid cryogens provide several advantages over liquid ones, including elimination of phase-separation issues, providing higher density and heat capacity and yielding more stable temperature control.

2.Some of the advantages of a solid cooler are the relative simplicity and absence of moving parts.

3.By speaking of engineering aspects of solid cryogen coolers, it is necessary to make acquaintance with the solid cryogen dewar.

4.The structural supports in solid cryogen dewar are made using lowconductivity tubes.

5.The goal of the gap construction is to achieve maximum thermal benefit from the evaporating cryogen.

6.The solid cryogen is the primary cooling force in the system.

Exercise 2. Translate the forms of Gerund and define their function:

1.Cooling with solid cryogens is considered to be the perspective trend in cryogenic engineering.

2.The use of stored cryogen has provided a reliable and simple method of cooling.

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3.The stored cryogen systems provide cooling of the desired load.

4.For the solid cryogens, the temperature may be modulated by varying the backpressure.

5.The normal operating regime of a solid cryogen cooler is below its triplepoint temperature.

6.The solid cryogen can be converted into vapor by passing the liquid state.

7.Operating below the triple-point eliminates the problems of fluid manage-

ment.

8.With the high cost of designing and servicing solid coolers, the mechanical cryocoolers became the choice for space missions.

9.Working with the solid phase provides greater density.

10.The minimum operating temperature depends on the minimum backpressure.

11.There is considerable benefit associated with extracting the available heat from the vapor.

12.There is the need for thermally conductive matrix and freezing coils in a solid cryogen dewar.

13.A means to freeze the cryogen is accomplished by providing a cooling coil within the dewar.

14.The process of freezing the cryogen or precooling it to the temperatures below its freezing point, requires great care and experience to avoid damaging the dewar.

Read the text, telling of solid cryogens application:

Text

Cooling with Solid Cryogens

For many years, the use of stored cryogen systems has provided a reliable and relatively simple method of cooling over a wide range of temperatures – from 4K for liquid helium to 77K for liquid nitrogen, up to 150K for solid ammonia. These systems rely on the boiling or sublimation of the low-temperature fluid or solid cryogens to provide cooling of the desired load. For solid cryogens, the temperature achieved may be modulated to a modest extent by varying the backpressure on the vented gas from atmospheric pressure down to a hard vacuum.

Solid cryogens are mostly used below their triple point where sublimation occurs directly to the vapor state. They provide several advantages over liquid cryogens

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including elimination of phase-separation issues, providing higher density and heat capacity, and yielding more stable temperature control, which is desirable for many applications.

One of the efficient ways to use stored cryogens is in the frozen state. The normal operating regime of a solid cryogen cooler is below its triple point temperature. In this region, the addition of heat causes conversion of the solid directly into vapor through the process of sublimation, by passing the liquid state. Operating below the triple point also eliminates the problems of fluid management and phase separation with fluid systems.

For the temperatures below 2K, space cryogen-cooled missions used solid cryogens. The first operational long-life solid cooler used in space was a single-stage carbon dioxide system developed by Lockheed Martin and launched aboard an Air Force satellite on October 20, 1972. Since that time nearly a dozen cooler designs, both singleand two-stage, have been used to cool sensors to temperatures over a range of 10 to 65K, with operational lifetimes from 10 months to 2.5 years.

With the rapid development of long-life mechanical refrigerators and the relatively high cost of designing and servicing solid coolers, mechanical cryocoolers have increasingly become the cooler of choice for space missions that historically would have used solid cryogen cooler.

To the solid cryogens belong: ammonia (NH3), carbon dioxide (CO2). methane (CH4), oxygen (O2), argon (A), carbon monoxide (CO), nitrogen (N2), neon (Ne). They are considered in terms of the following thermal properties: heat of sublimation (J/g), density at melting point (kg/m3), temperature range (K).

From an efficiency point-of-view, working with the solid phase provides greater density (and thus lower storage volume) and higher heat content per unit mass of cryogen. Other advantages of a solid cooler are the relative simplicity, absence of moving parts, absence of noise and vibration, excellent temperature stability and no power requirements.

The primary limitations or disadvantages include a limited number of suitable cryogens, very large mass and volume, the need for very significant ground servicing facilities and manpower support and safety implications associated with venting toxic or flammable vapors or having a vent become clogged-causing an explosion.

The important interrelationship between the temperature and pressure of a frozen cryogen is expressed in that the sublimation temperature is strongly dependent

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on the vapor pressure maintained above the solid. Thus, given a fixed back pressure, a solid cryogen can be designed to maintain a very stable temperature. In other words, the minimum operating temperature depends on the minimum back-pressure that can be sustained during cooler operation. If the heat load is small enough and the applied vacuum is high enough, then lower pressure and thus lower temperatures can be attained.

By speaking of engineering aspects of solid cryogen coolers, it is necessary to make acquaintance with the solid cryogen dewar construction features (fig. 1):

Solid Cryogen in foam matrix

Low conductance structural supports

Fig. 1. Example solid cryogen dewar construction features

Solid cryogen dewar systems are fundamentally similar to liquid cryogen dewars in their structural support and thermal insulation systems. Both include a nested storage tank, the inner tank, which holds the solid cryogen, and is suspended inside an outer vacuum shell with low-conductivity structural supports.

As with liquid cryogen dewars, these structural supports are typically made using low-conductivity tubes, struts or tension bands in order to achieve high structural efficiency and minimum conductivity between the two tanks. The gap between the two tanks is evacuated and filled with Multilayer Insulation (MLI) and for high efficiency of the dewars, one or more vapor-cooled shields (VCS) may be placed inside the gap. The goal of the gap construction is to prevent gaseous conduction and radiation between the outer and inner tank and to achieve maximum thermal benefit from the evaporating cryogen.

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The solid cryogen, by this, is the primary cooling force in the system. There is also considerable benefit associated with extracting the available heat from the vapor as it rises up in temperature from the cryogen temperature to the external vent temperature.

Two key differences between liquid and solid cryogen dewars are the need for a thermally conductive matrix and freezing coils in a liquid cryogen dewar. The second addition to a liquid cryogen dewar is a means to freeze the cryogen in place within the foam-filled dewar. This is accomplished by providing a cooling coil within the dewar that can be connected to an external coolant source sufficiently cold to freeze the cryogen. This process of freezing the cryogen or precooling it to the temperatures below its freezing point, requires great care and experience to avoid damaging the dewar.

Exercise 3. Compose the pairs of synonyms:

Exercise 4. Compose the pairs of antonyms:

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Speaking

Case 1

Find in the text the sentences corresponding to the following statements:

1.Applying reserved cryogen systems resulted in new procedures of cooling.

2.A lot of temperature conditions were created due to both liquid and solid

gases.

3.The necessary low temperatures can be achieved by sublimation of extremely cold fluids.

4.Solid cryogens are mainly used by sublimation leading to the vapor state.

5.Solid cryogens present some better opportunities in comparison with the liquid ones.

6.The frozen cryogen should pass the liquid state before converting into

vapor.

7.Solid cryogens are used to achieve the temperatures below 2K for astronautics

needs.

8.Mechanical cryocoolers replaced using solid ones because of their high

cost.

9.The group of solid cryogens includes the great number of gaseous subs-

tances.

10.The solid coolers possess several desirable characteristics: great density by small volume, elimination of friction details, temperature stability and they are noiseless and free of vibration.

11.The drawback of using solid cryogens is high safety observation because of toxicality of vented gases and fire dangerous vapors.

12.Very important thing of using solid cryogens is the correlation of temperature and pressure.

13.It is very important to support permanent temperature depending on the backpressure.

14.Solid cryogen vessels have the same structural design as the liquid systems.

15.However, there are two main different items between liquid and solid facilities.

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Case 2

Speak English on the following information, finding answers in the corresponding parts of the text:

1.How a wide range of temperatures was created for a long time.

2.The advantages of solid cryogens over the liquid ones.

3.The most suitable means of using stored cryogens.

4.What does usual operating regime of solid cryogens consist of.

5.The application of solid cryogen coolers in space missions.

6.Why the usage of solid cryogens became unprofitable.

7.What cryogens are referred to the solid ones.

8.What are the advantages of solid cryogens.

9.What is the most famous solid cryogen construction.

10.What is the design of cryogen structures.

11.What are the differences between liquid and solid cryogen dewars.

12.What are precautions (предосторожности) by operating cooling units.

Case 3

Speak on solid cryogens application:

1.Did you concern with cryogenic substances?

2.What are cryogens? What is their function in engineering?

3.Have you been to any chemical enterprise? Was it practical work or excursion?

4.Can you tell what chemical enterprises are there in the city where you live or

study?

5.Can you describe such chemical process, as sublimation?

6.Are you acquainted with structural design of a cooler?

7.What is the difference between solid and liquid cryogens?

8.Why do the space missions take an active part in production and usage of cryogens?

9.What could you contribute to cryogenic engineering after graduating from the university?

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SECTION III

Vapor-Compression Refrigeration Systems

Grammar: Gerund, Participle I.

Word-formation: Suffix -ly.

Speaking: Ideal and Actual vapor compression cycles.

Learn the pronunciation and the meaning of the words:

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irreversibility [,ɪrɪvəsɪ'bɪlɪtɪ] необратимость, неотменяемость, непреложность

Grammar study: Gerund, Participle I

Brief characteristics of Gerund and Participle I see in Section I, subsection “Vocabulary development”.

Vocabulary development: word-formation: suffix -ly

Суффикс -ly образует наречие от различных частей речи: прилагательного, существительного, обозначающего периоды времени, порядковых числительных и причастий со значением “как происходит действие”.

Samples: light (adj) легкий – lightly (adv) легко; day (n) день – daily (adv) ежедневно;

first (num) первый – firstly (adv) во-первых;

exceeding (Part. I) превосходящий – exceedingly (adv) чрезвычайно; decided (Part. II) решительный – decidedly (adv) решительно.

Exercise 1. Find in the text the forms of Gerund and Participle I and translate them in the context:

cooling, understanding, decreasing, achieving, involving, working, conditioning, vaporizing, replacing, throttling, condensing, connecting, depending, mixing.

Exercise 2. Find in the dictionary the original word of the following adverbs and translate them:

respectively widely completely reversibly adiabatically precisely slightly mostly

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