yashchuk_tsepkalo (1)

participate in the conference organized by one of the leading universities.

Think over what you will report about.

8.Pick up the key words from the text “Mixing and blending”. Make up your own sentences with them.

9.Write an abstract to the text “Mixing and blending”.

10.Get ready for presenting the topic “Mixing and blending” at the conference ”Innovations in Science and Engineering” based on the following questions of Task 4.

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LESSON 7

1.Read and memorize the following words:

2.Read and memorize the following word combinations:

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3.Read and translate the text into Ukrainian:

Heat exchangers

A heat exchanger is a specialized device that assists in the transfer of heat from one fluid to the other. In some cases, a solid wall may separate the fluids and prevent them from mixing. In other designs, the fluids may be in direct contact with each other. In the most efficient heat exchangers, the surface area of the wall between the fluids is maximized while simultaneously minimizing the fluid flow resistance. Fins or corrugations are sometimes used with the wall in order to increase the surface area and to induce turbulence.

The main use of heat exchangers is in industrial procedures. They are often brought to use in heating processes. They can also be applied for heat and energy saving as heat exchangers are used to recover lost heat energy in industries and the recovered heat energy is then used to heat another stream, thus eliminating the need for another heat source and putting the otherwise lost and wasted heat to use.

Heat exchangers have found their use in several industries; most importantly, the petroleum industry, food industry, waste water treatment industry and wine industry. Heat exchangers are used in chemical processing and power production. They are also used widely in spacecrafts and airplanes to heat fuel. Air conditioning and refrigeration systems are some other important fields where heat exchangers are applied.

There are three primary flow arrangements with heat exchangers: counterflow, parallel-flow, and cross-flow. In the counter-flow heat exchanger, the fluids enter the exchanger from opposite sides. This is the most efficient design because it transfers the greatest amount of heat. In the parallel-flow heat exchanger, the fluids come in from the same end and move parallel to each other as they flow to the other side. The cross-flow heat exchanger moves the fluids in a perpendicular fashion.

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There are also four different designs of heat exchangers: shell and tube, plate, regenerative, and intermediate fluid or solid. The most typical type of heat exchanger is the shell and tube design. This heat exchanger has multiple finned tubes. The tubes carry the liquids that will be processed by the exchanger. One set of tubes will carry the medium that will be in need of cooling. The other set of tubes will carry the liquid that will run through the other medium and provide the cooling for it. This process also goes the other way with the mediums either being cooled or heated.

The set of tubes present in a shell and tube heat exchanger is called a tube bundle. The tube bundle is comprised of several different tubes in all shapes and sizes. A shell and tube heat exchanger is usually used for jobs that would require high pressures. The pressures that this particular exchanger typically deals with can be around 30 bars and be as high as 260°C. The strength of the tubes that make up this particular heat exchanger enables it to handle pressures high.

In the plate heat exchanger, the fluid flows through baffles. This causes the fluids to be separated by plates with a large surface area. This type of heat exchanger is typically more efficient than the shell and tube design.

The regenerative heat exchanger takes advantage of the heat from a specific process in order to heat the fluid used in the same process. These heat exchangers can be made with the shell and tube design or the plate design. The intermediate fluid or solid heat exchanger uses the fluids or solids within it to hold heat and move it to the other side in order to be released. This method is commonly used to cool gases while removing impurities at the same time.

To ensure good condition of a heat exchanger and to prevent contamination and any blockage due to impurities collected in a heat exchanger, a regular and timely examination of heat exchangers is essential.

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4.Answer the questions to the text:

1)What is a heat exchanger?

2)What separates the fluids and prevents them from mixing?

3)Why are fins or corrugations sometimes used with the wall?

4)What can heat exchangers be used for?

5)In what industries have heat exchangers found their use?

6)What are three primary flow arrangements with heat exchangers?

7)How is a shell and tube heat exchanger designed?

8)How does a regenerative heat exchanger work?

5.Choose the correct continuation to complete the following statements:

1)The fluids may be separated and prevented from mixing

a)by a solid wall

b)by a specialized device

2)In the most efficient heat exchangers, the surface area of the wall between the fluids

a)is maximized

b)is minimized

3)Heat exchangers are often brought to use in

a)heating processes

b)industrial procedures

4)Some other important fields where heat exchangers are applied.

a)air conditioning and refrigeration systems

b)spacecrafts and airplanes

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5)The fluids come in from the same end and move parallel to each other as they flow to the other side

a)in the parallel-flow heat exchanger

b)in the counter-flow heat exchanger

6)For jobs that would require high pressures

a)a shell and tube heat exchanger is usually used

b)a plate heat exchanger is usually used

6.Fill in the gaps with the suitable words from the box:

a)treatment b) heat c) arrangements d) refrigeration

d)tube e) spacecrafts f) finned g) flow

1.fluid _____resistance

2.waste water _______industry

3.to recover lost _______energy

4.primary flow _______with heat exchangers

5.multiple ______tubes

6.shell and _______design

7.to be used widely in______ and airplanes

8.air conditioning and______ systems

7. Which of the following sentences from the text contain the Passive

Voice forms? Explain how you define these forms.

1.A solid wall may separate the fluids.

2.Fins or corrugations are sometimes used with the wall

3.Heat exchangers have found their use in several industries.

4.The main use of heat exchangers is in industrial procedures.

5.In the counter-flow heat exchanger, the fluids enter the exchanger from opposite sides.

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6.The set of tubes present in a shell and tube heat exchanger is called a tube bundle.

7.The tube bundle is comprised of several different tubes in all shapes and sizes.

8.A regular and timely examination of heat exchangers is essential.

6. Say if the following statements are true or false. If the statement is false

explain why:

1)A heat exchanger is a specialized device that separate the fluids and prevent them from mixing.

2)Fins or corrugations are sometimes used with the wall in order to minimize the fluid flow resistance.

3)Heat exchangers are used to recover lost heat energy in industries

4)Because of transferring the greatest amount of heat cross-flow heat exchanger is the most efficient design.

5)The most typical type of heat exchanger is the shell and tube design.

6)The strength of the tubes that make up a shell and tube heat heat exchanger enables it to handle temperatures high.

7)Regenerative heat exchangers can be made with the shell and tube design or the plate design.

8)To prevent contamination and any impurities collected in a heat exchanger, a regular and timely blockage of heat exchangers is essential.

7. Imagine that you are a representative of the company that manufactures four different designs of heat exchangers: shell and tube, plate, regenerative and intermediate ones. At this moment you are at the engineering fair. There are some representatives of competitive companies designing the same types of heat exchangers. You have to exert every effort in order to persuade the potential customers of buying nothing but your manufactured articles. So think over a brief informative presentation.

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LESSON 8

1.Read and memorize the following words:

2.Read and memorize the following word combinations:

3.Read and translate the text into Ukrainian:

Crushers

A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or

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to reduce the size of a solid mix of raw materials (as in rock ore), so that pieces of different composition can be differentiated.

Crushing is the process of transferring a force amplified by mechanical advantage through a material made of molecules that bond together more strongly, and resist deformation more, than those in the material being crushed do. Crushing devices hold material between two parallel or tangent solid surfaces, and apply sufficient force to bring the surfaces together to generate enough energy within the material being crushed so that its molecules separate from (fracturing), or change alignment in relation to (deformation), each other. The earliest crushers were hand-held stones, where the weight of the stone provided a boost to muscle power, used against a stone anvil. Querns and mortars are types of these crushing devices.

In industry, crushers are machines which use a metal surface to break or compress materials. Mining operations use crushers, commonly classified by the degree to which they fragment the starting material, with primary and secondary crushers handling coarse materials, and tertiary and quaternary crushers reducing ore particles to finer gradations. Each crusher is designed to work with a certain maximum size of raw material, and often delivers its output to a screening machine which sorts and directs the product for further processing. Typically, crushing stages are followed by milling stages if the materials need to be further reduced. Crushers are used to reduce particle size enough so that the material can be processed into finer particles in a grinder. A typical circuit at a mine might consist of a crusher followed by a SAG mill followed by a ball mill. In this context, the SAG mill and ball mill are considered grinders rather than crushers.

In operation, the raw material (of various sizes) is usually delivered to the primary crusher's hopper by dump trucks, excavators or wheeled front-end loaders. A feeder device such as a conveyor or vibrating grid controls the rate at which this material enters the crusher, and often contains a preliminary

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