- •Міністерство аграрної політики україни
- •Table of Contents. (Зміст)
- •Plate Heat Exchanger. ( The main components).
- •1. Match the words from the left column with their translations in the right
- •2. Make up sentences with the key words.
- •3. Read the text and find the sentences with the key words in the text. Main components.
- •4. Discuss the questions.
- •Vocabulary.
- •A direct expansion evaporator.
- •1 Match the key words with their translations.
- •2. Write your ideas of what you would like to know about a direct expansion evaporator.
- •3. Read the text and say if you have found the answer. A direct expansion evaporator.
- •Vocabulary.
- •Flooded flow
- •Flooded flow.
- •6. Complete the sentences.
- •7. Discuss the questions
- •8. Complete the sentences with the correct form of the verbs in bra-
- •9. Translate these sentences into English.
- •Vocabulary.
- •The basic refrigeration cycle.
- •1. Match the words from the left column with their definitions in the right column.
- •2. Write your ideas of what you would like to know about the basic refrigeration cycle.
- •3. Read the text and say if you have found the answer. The basic refrigeration cycle.
- •4. Find the sentences with the key words in the text guess the meaning. Use a dictionary to check the answer.
- •5. Discuss the questions.
- •1. Read the text, find the sentences with the key words and guess the meaning. Use a dictionary to check the answer. The basic refrigeration cycle. Part 2
- •2. Read the text again. Answer these questions.
- •The expansion process and devices
- •In all types of the refrigeration cycle there is a step where liquid refrigerant is expanded from the condensing pressure to the evaporating pressure. Refrigerant evapo-
- •2. Read the text again and correct the mistakes. Begin your answer with:
- •3. Complete the sentences.
- •4. Give affirmative answers to the following questions according to the given model:
- •5. Complete the with the correct forms of the verbs given in brackets.
- •Vocabulary
- •1. Match the words from the left column with their definitions in the right colomn.
- •2. Write your ideas of what you would like to know about the pressure drop.
- •3. Read the text and say if you have found the answer. Methods to control the pressure drop
- •4. Find the key words in the text and guess the meaning. Use a dictionary to check the answer.
- •5. Discuss the question.
- •Vocabulary.
- •The compressor.
- •1. Match the words with their translation.
- •2. Read the text and answer the questions.
- •Evaporators, condensers and interchangers.
- •1. Match the Key words with their translation.
- •2. Use your knowledge and answer the questions.
- •3. Now read the text quickly and check your guesses. Evaporators, condensers and interchangers.
- •4. Read the text more carefully.
- •6. Make these sentences negative.
- •Vocabulary.
- •Literature.
- •Рецензія
Vocabulary.
separate - отделять
droplet - капля
partly - частично
emerging - выходящий
emerge - выходить
re-enter - возвращаться
expansion - расширение
join - соединять
leave - покидать, оставлять
superheated - перегретый
level - уровень
instead - вместо
8
The basic refrigeration cycle.
Key words
refrigeration plant, process fluid, recipient, an evaporator, compressor, condenser, device, pipe liquid, pressure, saturation curve, a valve, isenthalpic, decrease.
1. Match the words from the left column with their definitions in the right column.
1. a refrigeration plant- a. a tube from which liquid or gases can flow,
2. process- b. a mechanical device for controlling the flow liquid, gas in one
direction only.
3. compressor- c. the cooling or freezing of food in order to preserve it,
4. valve - d. become shorter, smaller, less,
5. device- e. a device for pressing something,
6. pipe- f. substance that flows freely and is neither a solid nor a gas,
7. decrease- g. something invented for a special purpose,
8. liquid- h. method, especially one used in manufacture or industry.
2. Write your ideas of what you would like to know about the basic refrigeration cycle.
3. Read the text and say if you have found the answer. The basic refrigeration cycle.
Part 1
The function of the refrigeration plant is to remove heat from a process fluid or air at a low temperature and dump it in recipient tha can be water or air. A cooling plant is composed of an evaporator, a compressor, a condenser, an expansion device and connecting pipes. These are the minimum components necessary in the basic refrigeration cycle.
To study the cycle we can work it through, starting at any point but a good starting point is usually the slightly subcooled liquid refrigerant, 35 °C at a pressure of 15.33 bar, i.e. a saturation temperature of 40 °C. This is point A in the figure.
This starting point is suitable because it normally changes very little, regardless of the modification of the basic cycles.
The liquid expands in the expansion valve. No energy-thermal or mechanical - is exchanged with the surroundings; the expansion is isenthalpic
When the pressure starts to decrease, at first nothing happens; the temperature remains (almost) constant. The liquid reaches its saturation curve, though. A further decrease in pressure means that the temperature has to decrease as well; otherwise, the liquid would be super-heated, which is a thermodynamically unstable state.
The liquid is thus cooled down and the energy released evaporates a part of the liquid or, expressed differently, the evaporating liquid cools down the remaining liquid. The lower the pressure, the more liquid evaporates.