informe final tÍtulo del proyecto de investigaciÓn · 2 ˝ndice pÆgina 1. resumen 4 2....

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INFORME FINAL

TÍTULO DEL PROYECTO DE INVESTIGACIÓN:

TEXTO: “INGLÉS TECNICO PARA ESTUDIANTES DE INGENIERÍA EN

ENERGÍA”

INVESTIGADOR RESPONSABLE O JEFE DEL PROYECTO:

Ing. María Luisa Apolinario Peña

Resolución Rectoral Nº 053-2011-R

Periodo:01 Enero del 2011 al 31 Diciembre del 2011

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ÍNDICE

Página

1. RESUMEN 4

2. INTRODUCCIÓN 5

3. MARCO TEÓRICO 7

4. MATERIALES Y METODOS 8

5. RESULTADOS 9

5.1 UNIT ONE: THEORY OF HEAT 10

5.1.1 GENERAL 11

5.1.2 HEAT MEASUREMENT 11

5.1.3 HEAT TRANSMISSION 12

5.1.4 CLASS WORK ASSIGNMENT 15

5.2 UNIT TWO: REFRIGERATION CYCLE 16

5.2.1 REFRIGERATION CYCLE 17

5.2.2 BASIC COMPONENTS 18

5.2.3 COMPRESSOR 19

5.2.4 COMPRESSOR OPERATION 20

5.2.5CLASS WORK ASSIGNMENT 22

5.3 UNIT THREE: CONDENSER / RECEIVER 23

5.3.1CONDENSER 24

5.3.2 RECEIVER 26


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5.4 UNIT FOUR: OTHER COMPONENTS 30

5.4.1 METERING DEVICES 30

5.4.2 THERMOSTATIC EXPANSION VALVE 30

5.4.3 CAPILLARY TUBE 31

5.4.4 EVAPORATOR 32

5.4.5 DRIER 33

5.4.6 CHECK VALVE 34

5.4.7 SIGTH GLASS 35


UNIT FIVE: TOOLS AND EQUIPMENT 39

5.1 PRESSURE GAUGES 40

5.2 GAUGE MANIFOLD SETS 41

5.3 PRESSURIZED GAS 42

5.4 EVACUATION PUMP 43

5.5 LEAK TESTING 44

5.6 CLASS WORK ASSIGNMENT 46

6. DISCUSION 51

7. REFERENCIALES 52

8. APENDICE 53

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1. RESUMEN

El presente texto está preparado para el curso de Inglés Técnico que se dicta en el segundo Ciclo

de la Escuela Profesional de Ingeniería en Energía, tiene una estructura didáctica e ilustrativa en el

desarrollo de sus capítulos, tales como: teoría del calor, ciclo de refrigeración que tienen

compresor, condensador y otros componentes. Además de equipos y herramientas. Se presenta

con una redacción sencilla para la definición y descripción del ciclo de refrigeración empleados en

procesos industriales.

La obra alecciona al estudiante empleando un lenguaje formal de Inglés Técnico de fácil

accesibilidad y entendimiento en los cinco tópicos con el tema central que es el ciclo de

Refrigeración por compresión de vapor que consta de cuatro procesos.

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2. INTRODUCCIÓN

En nuestro mundo globalizado se hace necesaria la utilización del inglés técnico, debido a que se

ha tomado como un idioma universal para poder comprender las tecnologías y de esta manera

poder acortar la distancia entre su utilización y la aplicación de los componentes y partes.

El texto: “Ingles Técnico para Estudiantes de Ingeniería en Energía” es un material didáctico

escrito con la finalidad de facilitar el aprendizaje en el desarrollo de la formación y capacitación

en la que ocupará el Ingeniero en Energía, dejando la posibilidad de un mejoramiento y

actualización permanente.

El texto: “Ingles Técnico para Estudiantes de Ingeniería en Energía” es bastante versátil y facilita al

estudiante el estudio de la termodinámica ya que es una ciencia que comprende el estudio de las

transformaciones energéticas y de las relaciones entre las propiedades físicas de las sustancias

afectadas por dichas transformaciones, ejemplo: procesos de refrigeración y acondicionamiento

de aire, los expansores y compresores de fluidos, motores de aviación y los cohetes, etc.

La presentación de este material didáctico responde a la problemática: ¿es posible conocer y/o

familiarizarse con terminologías del idioma inglés en especial el inglés técnico empleado en el

conocimiento del área de ciencias e ingeniería actualizado?

Planteado el problema de investigación, se trabajó para lograr los objetivos propios explicitados

en elaborar un texto de inglés Técnico dirigido a Estudiantes de Ingeniería en Energía teniendo

como objetivo especifico utilizar un lenguaje formal técnico de fácil accesibilidad y entendimiento

para estudiantes de Ingeniería en Energía. De esta manera, la investigación está orientada a

fortalecer la formación profesional y de allí nace la importancia y justificación del presente

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proyecto de investigación, titulado texto: “Ingles Técnico para Estudiantes de Ingeniería en

Energía”, que tiende a ser un texto que permitirá facilitar al estudiante a través del lenguaje

formal técnico en ingles su proceso de aprendizaje en el desarrollo de la formación y capacitación

universitaria.

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3. MARCO TEORICO

Para el tema central de este texto se recurrió a las fuentes de información primaria o directa

citadas en la referencia para un posterior análisis en sus contenidos de conceptos básicos del ciclo

de Refrigeración.

El texto en su desarrollo tiene orden lógico y sistematizado acerca del Ciclo de Refrigeración por

compresión de vapor el cual consta de cuatro procesos, para su aplicación en un proceso

industrial.

Cabe resaltar que cada uno de los capítulos, tiene el propósito de que el estudiante ingrese a la

competencia profesional empleando terminologías propias de ingeniería a través del Ingles

Técnico, que contribuirá a despertar en él, la inquietud por la investigación.

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4. MATERIALES Y METODOS

Dado que la presente investigación no es de tipo EXPERIMENTAL sino de carácter teórico en nivel

de la INVESTIGACION BASICA (elaboración de texto), no es posible incluir materiales o métodos

seguidos para su realización como por ejemplo el método estadístico.

Muy por el contrario por el carácter mismo de la presente investigación como es la elaboración

del texto de “Inglés Técnico para Estudiantes de Ingeniería en Energía” se ha tomado en

consideración la revisión de cierta bibliografía en el campo de la Termodinámica teniendo como

valor agregado la experiencia del autor que se traduce como lecciones aprendidas.

La forma como se presenta este trabajo de investigación constituye un intento por complementar

la asignatura de Inglés Técnico empleando un método pedagógico y deductivo.

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5. RESULTADOS

El resultado del proyecto de investigación que se presenta a la comunidad universitaria en calidad

de texto de “Inglés Técnico para Estudiantes de Ingeniería en Energía”, nos permitirá contar con

un material bibliográfico práctico, el mismo que puede ser utilizado por los estudiantes de

Ingeniería Mecánica – Energía y ramas afines, en el área académica del campo de la

Termodinámica, asignatura que forma parte del Plan de Estudios de la Escuela Profesional de

Ingeniería en Energía de la Universidad Nacional del Callao.

El tema tratado en el presente texto explica en forma clara y sencilla, permitiendo comprender los

principios básicos de esta ciencia que ha sido durante mucho tiempo parte esencial de la

educación en Ingeniería. Resaltando el empleo del lenguaje formal técnico en inglés, lo cual

permite mejorar y acelerar el proceso de aprendizaje del estudiante en el desarrollo de su

formación académica universitaria, manifestándose a través de la lectura, traducción de

manuales, hojas de información, revistas, manuales técnicos-científicos.

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5.1 UNIT ONE: THEORY OF HEAT

OBJETIVES

1. Given the task of defining the term “heat” the student will correctly state the meaning of

this word.

2. Given a picture of two objects with different temperatures, the student will orally or/and

in writing identify the direction of heat flow.

5.1.1 GENERAL

Heat is very relative term. Usually one thinks of it as a means of warming the body, or

same object, to a desire temperature. Strange as it may seem, heat is ever present, even in a

block of ice. In this unit, heat is explained in term of how it is used and transferred from

substance. Heat transfer is what all refrigeration systems are designed to accomplish. Look at

figure 1.

Figure1 All substances contain heatSource: ( yunus, 2009)

Heat is often defined as energy in transfer, for it is never content to stand still, but is always

moving from a warm body to a colder body.

Look at figure 2. A spoon in ice water loses its heat to the water and becomes cold; a spoon in hot

coffee absorbs heats from de coffee and becomes warm. But the terms warmer and colder are

only comparative.

A

(A) (B) (C) (D)

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Figure 2(a) Spoon heating (b) Spoon cooling© Vol 1/Photo Disc Yunus A. Cengel

Heat exists at any temperature above absolute zero, even though it may be extremely small

quantities. Absolute zero is the term used to describe the temperature at which no heat exists. It

is approximately 460 degrees below zero Fahrenheit.

5.1.2 HEAT MEASUREMENT

The temperature or INTENSITY of heat is measured with a thermometer. While both

Celsius (ªC) and Fahrenheit (ªF) are sometimes used, the majority of references in this manual will

be to Fahrenheit.

A temperature Reading tells us only the heat intensity of SENSIBLE HEAT a substance and not the

actual quantity of heat. Look at figure 3, it shows the comparison of temperature scales.

Heat QUANTITY, or the amount of heat in a substance, is measured in “”British Thermal Units”

(BTU´s).

One BTU is the amount of heat required to raise the temperature of one pound of water one

degree Fahrenheit (at sea level). This quantity measurement is commonly used in air conditioning

to describe heat transfer during changes of state.

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5.1.3. HEAT TRANSMISSION

5.1.3.1 HEAT CAN TRAVEL IN ANY OF THREE WAYS: RADIATION, CONDUCTION, ORCONVENTION

Radiation is the transfer of heat by waves similar lo light waves or radio waves. For example, the

sun´s energy is transferred to the Earth by radiation. Look at figure 4.

There is little radiation al low temperatures, and at small temperaturedifferences, so radiation is

of little importance in the actual refrigeration process. However, radiation to the refrigerated

space or product from the outside environment, particularly the sun, may be a major factor in the

refrigeration load.

(a) (b)

Figure 4RADIATION© Vol 1/Photo Disc Yunus A. Cengel

Figure 3 SCALE FAHRENHEIT, CELSIUS,

KELVIN

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Now, look at figure 5. Conduction is the flow of heat through a substance. Actual physical contact

is required for-heat transfer to take place by this means. Conduction is highly efficient means of

heat transfer.

Figure5CONDUCTION© Vol 1/Photo Disc Yunus A. Cengel

Figure 6 illustrates convection. It is the flow of heat by means of a fluid medium, either gas or

liquid, normally air or water. Air heated by furnace, and then discharged into a room heats

objects in the room by convection.

Figure6CONVECTION© Vol 1/Photo Disc Yunus A. Cengel

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Look at figure 7. In a typical refrigeration application, heat will travel by a combination of

processes, and the ability of a piece of equipment to transfer heat is referred to as the ever all

rate of heat transfer. Different materials vary in their ability to conduct heat. Metal is a very good

heat conductor, while asbestos has so much resistance to heat flow it can be used as insulation.

Figure 7 CONDUCTION / RADIATION / CONVECTION© Vol 1/Photo Disc Yunus A. Cengel

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5.1.4 CLASS WORK ASSIGNMENT: UNIT ONE

1. A _______________ system is designed to____________ heat from________ substance.

Everything has ____________ present, so we define it as_______________ in transfer.

2. Are temperature and Heat equal? Why?

3. Does absolute zero heat exist?

4. Temperature is the ______________of heat. It is measured with a device called

_____________of stands for__________ ____________. There is another scale

____________ of _____________ heat, but does not measure the_____________ (ºC).

Temperature indicates the ____________ of ______________ heat, but does not measures

the ________________ quantity of ________________.

5. The amount of___________ in a substance is called___________ ____________. The

quantity of__________ needed to raise the _____________ of ____________ pound of

water one degree______________ at ______________ level, is one _________. BTU stands

for _____________ ______________ ____________.

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5.2 UNIT TWO: REFRIGERATION CYCLE

OBJETIVES

1. Given a picture of a basis refrigeration system the student will orally or/in writing

correctly identify the following components:

. Compressor

. Condenser

. Receiver

. Expansion thermostatic valve

. Evaporator

2. Given a picture of a basic refrigeration system the student will describe the operation of

the system briefly.

3. Given the following terms the student will explain correctly the meaning of them:

. Cooling coils . Outlet side

. Mist . Drier

. Suction . Differential pressure

. Discharge . Refrigerant

. Piping . Efficiency

REFRIGERATION CYCLEFigure 8 REFRIGERATION CYCLE

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5.2.1 REFRIGERATION CYCLE

The refrigeration cycle is divided into two pressure sections, the high side and the

low side. The dividing lines between these two pressure areas are the compressor

discharge valves and the thermo-expansion valve as shown in figure 9. In the

direction of flow of the refrigerant, the high side starts as the pistons in the

compressor compress the gas and force it through the discharge valves. As the

pressure of thyme gas is increased, the temperature will also be increased. The hot

gases travel through the piping system to the condenser. The flow of the refrigerant

through this and other components in the system is considered in this unit. [1]

Figure 9 REFRIGERATION CYCLE

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5.2.2 BASIC COMPONENTS

Air conditioning system contains the following 5 basic components:

Compressor

Condenser

Receiver- Drier / Accumulator

Expansion Valve /Tube

Evaporator

Each of these components is necessary for system operation, and all are dependent upon

function of the one another. Additional components are used (supplemental controls), and

these vary according to application. Their use is to “fine-tune” and increase the efficiency of

the system.

Figure 10FIVE BASIC COMPONENTS

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5.2.3 COMPRESSOR

Compressor is of various makes and types, but they all operate as the “pump” of the

system to keep the refrigerant circulating to increase its pressure. Figure 12 shows a cutaway

view of a reciprocating compressor, and figure 14 illustrates a sectional view of a rotary vane

compressor.

Figure 11FIVE BASIC COMPONENTS

Figure 12COMPRESSOR

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5.2.4 COMPRESSOR OPERATION

The major components of a compressor are the body, crankshaft, rod, piston, valve plates and

head. All compressors do not operate the same. In the illustration 13, theRefrigerant enters a

suction part in the head and is drawn into the cylinder through the intake valve as the piston

moves downward.

As the piston moves upward, the refrigerant is compressed until the pressure below the discharge

valve exceeds the pressure above the valve and forces the refrigerant through the valve into the

system. The critical areas are the gaskets in the head and the suction and discharge valves. [1]

Compressor in the figure13

Figure 13COMPRESSOR OPERATION

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has slight changes from the previous compressor. The low pressure refrigerant enters through

the body and passes to an area around the sleeves. As the piston moves downward, it allows

refrigerant to pass through the parts in the cylinder walls, through passageway in the piston, and

through the inlet valve plate located on the crown of the piston.

During the upward stroke, the piston forces the refrigerant from the cylinder through the

discharge valve plate, into the head.

Compressor in figure 12, has the same feature as the one in the figure 13, except the flow of

refrigerant passes through the hollowed out passageway in the sleeve, then through the suction

valve plate into cylinder on downward stroke. The refrigerant passes through the discharge valve

plate on upward portion of the stroke.

Both compressors have spring loaded discharge valve plates that move slightly in case of liquid or

oil in the cylinder. This prevents the possibility of hydraulic lock-up that can cause severe damage

to the compressor.

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5.2.5 CLASS WORK ASSIGNMENT: UNIT TWO

1. The 5 basic components of a typical refrigeration system are:

(a) ________________

(b) ________________

(c) ________________

(d) ______________ ______________ or ______________ ______________

2. Look at figure 1 again.

a. The high side components are:

b. The low side components are:

3. The side of the system in which __________ pressure exists is called high_________ it begins

on ________ __________ of the compressor and goes through the ___________,

____________, ______________ and ______________ ______________ valve. The diving

point for high and low sides is ____________ _____________ or _______________

____________________.

4. Write the word true or false according with the following statements:

a. Pressures are the same in all parts of a refrigeration system. _______________.

b. The division of high side and low side always occurs at the same point in the system

____________.

c. System pressure in the evaporator is higher than the pressure in the condenser.

_________________.

5. In order for heat to move, a ______________ differential must be present.

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5.3UNIT THREE: CONDENSER / RECEIVER

OBJETIVES

Given a picture of the following components, the student will identify them correctly:

Air cooled condenser

Freshwater condenser

Sea water condenser

Receiver

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5.3.1 CONDENSER

The condenser consists of a series of tubes exposed to same cooling medium. This may be water,

air, or a combination of both.

5.3.1.1 AIR COOLED CONDENSER

The air cooled condenser location is very important and effect the efficiency of the unit. The flow

of air must be kept from recirculating over the coil. The recirculation of air would increase the

temperature and operating pressures of the refrigerant and may prevent the refrigerant from

condensing. This would allow the heat to be transmitted into the evaporator, coursing a reduction

in cooling capacity.

In the air cooled condenser the maintenance is very important. Maximum air flow must be

maintained through the air cooled condenser. Pressure washing or stem cleaning is normally

required to remove dirt and foreign objects that are forced into the fins. Acid cleaning is not

recommended because of the loss of heat transfer when the tubes or fins are etched with the

acid.[3]

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5.3.1.2 FRESH WATER CONDENSER

Now look at figure 15. The condenser consists of tubes in series with each other. These tubes then

are grouped in parallel passes through the coil. This configuration allows the size of the coil to be

reduced because of the increased heat transfer ability of the group of tubes. The fins increase the

size of the coil with respect to heat transfer area.[3]

The vessel and container units use a water-cooled condenser that also becomes a receiver tank

and stores the excess refrigerant. A tube type condenser has the refrigerant and the cooling

medium passing within a pipe inside. This then allows an effective method of the heat transfer.

Figure 14 AIR COOLED CONDENSER

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5.3.1.3 SEA WATER CONDENSER

The water-cooled condenser is cylindrical housing that contains a number of tubes through which

the cooling medium passes. The refrigerant enters the top of this cylinder, comes in contact with

the coolant tubes and condenses. The tanks also act as a receiver tank. This also provides a liquid

seal for the refrigerant to prevent vapor from entering the liquid line during normal operation.

5.3.2 RECEIVER

Receivers are installed to collect the liquid refrigerant as it leaves the condenser. In some models

the lower section of the condenser is used as the receiver. A receiver serves as a stowage for

refrigerant, maintains a liquid seal on the liquid line, and vents any air or non-condensable gases

back to the condenser.

Receivers are usually designed to be large enough to hold the complete charge of refrigerant

required to operate the unit. They are equipped with stop valves on the inlet and outlet lines to

permit the serviceman to pump the unit down when work is to be performed on another

component in the system.

Figure 15FRESH WATER CONDENSER

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During normal operation, the receiver is about 1/3 full of liquid refrigerant. On some models, sight

glasses are installed to show liquid level. On some models, the level is detected by an electronic

capacitance type probe mounted in the receiver an indicates, as a percentage of full on an

externally mounted meter.

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5.3.3 CLASS WORK ASSIGNMENT: UNIT THREE

1. Look at figure 1. It shows an _____________ cooled _____________. The principal function

of a condenser is to _____________ the refrigerant. It is made up of series of ___________

which are ________________ to a _____________ medium. In this type of condenser the

cooling ____________ is ____________

2. The ______________ is very important in an air ___________ condenser. In order toremove ____________ and _________ objects you should wash or __________ thecondenser ___________. ______________ cleaning is not recommended.

3. Look at figure 2. It is a ___________ water _______________.

a. Indicates the ______________ inlet

b. Indicates the ______________ outlet

c. Indicates the ______________ inlet

d. Indicates the ______________ outlet.

Figure 1

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4. The ___________ water ______________ is cooled by _____________ water. This kinds of

condensers require a very special ________________ due to the corrosive nature of

____________. The greatest hazard of this system is the possibility that __________ enters

the _______________ system, if the refrigerant __________ is ___________ by a

_____________.

5. Heat travels from a ____________ substance to a ____________ substance.

Figure 2

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5.4 UNIT FOUR: OTHER COMPONENTS

OBJECTIVE

Given a picture of different metering devices the student will identify orally or/and in writing

correctly the following devices:

Thermostatic expansion valves.

Capillary or expansion tubes.

5.4.1 METERING DEVICES

Metering devices are used to allow liquid refrigerant to enter the cooling coils as it needed. Some

of the most common metering devices are:

1. - Thermostatic expansion valves

2. - Capillary tubes

5.4.2 THERMOSTATIC EXPANSION VALVES

Most plants use the thermostatic expansion valves. The expansion valve is essentially a reducing

valve between the high pressure side and the low pressure side of the system. a cutaway view of

a typical thermostatic expansion valve is shown in figure 16.

The valve is designed to regulate the amount of refrigerant spray or mist, and the rate of

evaporation of the spray or mist is dependent upon the amount heat being absorbed from the

refrigerated spaces. As the liquid refrigerant passes from the expansion valve into the evaporator

coils. It is changed from a liquid into a fine mist or spray. Because heat is absorbed by the mist as

it travels through the cooling coils, the mist is evaporated, first into a saturated vapor, and then,

when all liquid has been changed to vapor, any additional heat that is absorbed by that vapors is

called superheated vapor form.

The operation of the thermostatic expansion valve in an air conditioning unit or a refrigeration

unit is basically the same.

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5.4.3 CAPILLARY TUBES

On most small hermetic seated units, the capillary tube or coke tube is used instead of the

expansion valve. Tubes sizes follow.

Table 1 Tubes sizes

When replacement of the tubes becomes necessary always use the size and length as the old

tube. Any deviation in size or length will change the capacity of the unit and amount of refrigerant

to operate at the desire temperature.

With such a small inside diameter, the tube presents a fluid flow restriction. the pressure of the

refrigerant decreases as it progresses through the tube. This produces the pressure difference on

Outside diameter Inside diameter

.083' .031'

.094' .036'

.109' .042'

.114' .049'

.120' .055'

.130' .065'

Figure 16THERMOSTATIC EXPANSION VALVE

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each side of the tube when the compressor is running. The refrigerant is sprayed into the cooling

coils and flashed into a low pressure, low temperature vapor to absorb the surrounding heat.

The capillary tube has two advantages over the expansion valve.

1. - There are no moving parts to wear or stick.

2. - When the compressor stops, the refrigerants pressure equalizes on the high and low side of

the compressor motor to star with a minimum starting load.

5.4.4 EVAPORATOR

Look at figure 18. The evaporator is a simple bank or coil of thin walled tubing. It is here the

refrigerator absorbs the heat from the surrounding area. The refrigerant enters the evaporators

from the expansion valve or metering devices as previously explained. Here, the refrigerant

absorbs heat and becomes superheat; it is then pumped back to the compressor.

Figure 17 EXPANSION TUBE

Figure 18 EVAPORATOR

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5.4.4 EVAPORATOR







32







5.4.4 EVAPORATOR







33

There are types of evaporators. One type, consisting of plain walled tubes, is used where space is

not a consideration, the other type consist of thin walled with attached fins to give more cooling

area within a small space.

5.4.5 DRIER

The operation of refrigeration system depends on the internal cleanliness of the refrigerant and

oil. There is no compromise for proper handling of these. But even with the greatest care some

moisture may enter the system. This must be entrapped to prevent the moisture from moving

about the system.

Moisture will cause the oil and refrigerant to breakdown and also cause the expansion valve to

components within the system. This contamination of the system, if not properly corrected, leads

to up to make the system suitable for reuse.

The procedure described pertains to moisture only; air must be removed by evacuation.

The chemicals (desiccant) will remove the moisture by absorption (no chemical change). The

chemical is activated alumina or silica gel. The safe level of moisture for on refrigeration system is

below 15 p.p.m. any level above this will cause corrosion, oil breakdown, and motor burn-outs.

While moisture removal is the primary function of the drier, two other features also enter in the

operation; they are acid removal and filtering out solids.

Figure 19 EVAPORATOR TUBING

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5.4.5 DRIER




about the system.











33




5.4.5 DRIER




about the system.











34

The capacity of drier is critical because the drier will not remove moisture beyond its capacity,

much like a sponge that cannot return any more moisture.

Look at figure 20. It shows a drier and its parts.

5.4.6 CHECK VALVE

Look at figure 21, it shows two different types of check or non return valves. The check valve

maintains the proper flow direction during heating or defrosting when the same system is used

for cooling cycle when the system is used for heating.

The size and construction varies, but the operation features are almost always the same.

The amount of pressure needed to open the check valve is very slight. The spring aids in closing

effort and the pressure difference then will complete the sealing.

Figure 20 DRIER

Figure 21 CHECK VALVES

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5.4.6 CHECK VALVE







Figure 20 DRIER


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5.4.6 CHECK VALVE







Figure 20 DRIER


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5.4.7 SIGHT GLASS

5.4.7.1LIQUID INDICATORS, SIGHT GLASS

The sight glass indicates the refrigerant flow to expansion valve. This should indicates a solid

stream of refrigerant. Bubbles appearing in the sight glass may be the result of excessive pressure

drop in the line or improper sub-cooling of the refrigerant.

5.4.7.2 MOISTURE INDICATOR, SIGHT GLASS

The moisture indicating sight glass is helpful in determining the level of moisture in the system.

The moisture indicator changes color to indicate the level of moisture within the system. Check

color of indicator against color decal on sight glass. Corrective action can be taken when moisture

becomes excessive. Figure 23 illustrates a moisture indicator.

Figure 22 LIQUID INDICATOR

Figure 23 MOISTURE INDICATOR

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5.4.7 SIGHT GLASS












35

5.4.7 SIGHT GLASS












36

Now let`s look at figure 24. A clear sight glass indicates the system has the correct charge of

refrigerant. It may also indicate that the system has a complete lack of refrigerant, a condition

accompanied by a lack of any cooling action by the evaporator. Also the sight glass may be clear

and the system might be overcharged (too much R-12). This must be verified with test gauge

readings.

A bubbly or “foamy” sight glass indicates the system is low on refrigerant, and air has probably

entered the system. However, if only occasional bubbles are noticed, during clutch cycling or

system start-up. This may be a normal condition.

If oil streaks appear on the sight glass, a lack of refrigerant may be indicates that the desiccant

contained in the receiver-drier (or accumulator) has broken down and is being circulated through

the system.

NOTE

Some sight glasses may be having a cup installed over the glass. This is for a keeping the glass

clean, and should be reinstalled after use. On some system without sight glasses, it is possible to

install an in line sight glass between the condenser and the thermostatic expansion valve. It

should be noted, however, that sight glass readings are not necessary positive identification of a

problem. Readings should be relied upon only in conjunction with other system symptoms.

Figure 24

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readings.






the system.

NOTE






Figure 24

36





readings.






the system.

NOTE






Figure 24

37

5.4..8CLASS WORK ASSIGMENT: UNIT FOUR

1. Look at figure 2. It illustrates an expansion _________________

a. Indicates the ______________ ______________ ______________

b. Indicates the ______________

c. Indicates the ______________

d. Indicates the ______________ ______________ ______________

Figura 1

2. What are two advantages of capillary tubes over the expansion valves?

3. Write the word true or false according with the following statements:

a. The orifice in the expansion valve divides the side of the system from the low

side________

b. Refrigerants have the same freezing point as water ________

c. During a change of state, there is no heat exchange ________

a. Evaporators, condensation and freezing are three forms of heat movement ________

4. Look at figure 3. It shows a drier.

38

a. Indicates the ________________

b. Indicates the ________________

c. Indicates the ________________

d. Indicates the ________________

e. Indicates the ________________

f. Indicates the ________________

Figura 2

5. The main purpose of _________is to remove __________. It performs its action by

___________but __________change. Other functions of a ________are ________removaland

filtering out of ____________. When the _________becomes saturated it cannot retain any

__________ _____________.

38

a. Indicates the ________________

b. Indicates the ________________

c. Indicates the ________________

d. Indicates the ________________

e. Indicates the ________________

f. Indicates the ________________

Figura 2




__________ _____________.

38

a. Indicates the ________________

b. Indicates the ________________

c. Indicates the ________________

d. Indicates the ________________

e. Indicates the ________________

f. Indicates the ________________

Figura 2




__________ _____________.

39

5.5 UNIT FIVE: TOOLS AND EQUIPMENT

OBJECTIVES

1. Given a picture with a cutaway view of a gauge, the student will orally or/and in writing

identify the following parts:

Bourdon tube

Link

Gear sector

Adapter

Calibration spring

Pointer

2. Given a task the student will describe the difference between a high pressure gauge and a

compound gauge.

3. Given a picture of a gauge manifold set the student will orally or/and in writing identify the

following features:

Compound gauge

Hand valve

Low side seat

Low side port

Manifold

Service port

High side port

High side seat

High pressure gauge

4. Given a task of describing the purpose of pressurized gas equipment the student will state

that the purposes of this equipment are:

Dehydration, testing and purging

5. Given a pictures of different leak detectors the student will correctly identify the following

types:

Halide propane torch detector

Electronic leak detector

Bubble leak detector

40

5.5.1 PRESSURE GAUGES

The pressure gauges allow us to the check conditions within a refrigeration system. The gauge

must have a high degree of accuracy and good life expectancy. The gauge should have a means of

recalibrating to compensate for wear and reset to original accuracy.

The two gauges types used in refrigeration system are the high pressure gauge and the compound

gauge.

Look at figure 25, it shows a sectional view of gauge. The constructions of a gauge consist of: A

threaded adapter, the bourdon tube, link and gear arrangement, the pointer and case.

The bourdon tube tends to straighten out as pressure increases. This movement causes the link to

move the gear. The pointer is attached to the gear and indicates the respective pressure in a

system.

The only difference between a pressure and a compound gauge is the relaxed location of the

pointer. The compound has the ability to read vacuum or less than atmospheric pressure. An

absolute gauge takes atmospheric pressure into account and reads approximately 14.7 PSI (1.1

KPa) when it is relaxed. Whit this arrangement is always positive.

Figure 25 GAUGES

41

5.5.2GAUGE MANIFOLD SETS

The gauge manifold consists of: a compound gauge, a high pressure gauge, hand valves and a

manifold that holds the gauges and hand valves.

Now look at figure 26, it indicates a gauge manifold. You can notice that the gauge is open to a

port to which a hose is attached. This hose placed on the proper fitting on the service valve.

Turning the hand valve clockwise closes the seat to the center port. This allows the gauges to read

pressure within the system and keeps the high and low sides isolated. Opening of either hand

valve will allow flow to the center port, which can be balanced from high to low side.

The accuracy of the gauge manifold depends on the quality of the pressures gauges and the care

that they receive

Figure 26 GAUGE MANIFOLD SE

41










that they receive


41










that they receive


42

5.5.3 PRESSURIZED GAS

The improper use of high pressure cylinders can cause a physical damage to components or

personal injure, or can cause stress would lead to failure of components.

Observe proper handling of cylinders, as follows:

Always keep protective capon cylinder when not in use.

Secure cylinder in proper storage area fastened to cart.

Do not expose it to excessive heat or direct sun light.

Do not drop, dent or damage the cylinder.

Open valve slowly, use regulators and safety valves that are in good conditions.

Look at figure 27. It illustrates pressure test equipment. Dehydration, pressure testing or purging

can be accomplished by the use of dry nitrogen (N2). The proper equipment and application of it

are very important.

PROCEDUREMAXIMUN PRESSURE

PSI KPa

Leak testing, low side 150-175 1034-1379

Leak testing, high side 200-250 1379-1724

Pumping dehydration 10-20 689-137.9

Table 2 Pressurized Gas

43

5.5.4 EVACUATION PUMP

The evacuation pump is used to removed air, moisture and non-condensable from a refrigeration

system. The procedure, condition and application all vary. There are different kinds of evacuation

pumps. Figure 28 shows an arrangement using an evacuation pump.

Figure 27 PRESSURIZED EQUIPMENT

Figure 28EVACUATION PUMP

44

Some of the basics of this are:

1. How much air is left in a system?

2. What is the percentage of moisture removed?

3. What are safe levels of moisture or air?

The ability of a vacuum pump to remove air, moisture and non-condensable depends on the

pump construction and the maintenance the pump receives. Even a new pump can be ruined with

improper maintenance, poor quality oil, or extended use under high moisture conditions.

It is important to keep in mind that high moisture levels and high acid levels become synonymous.

A safe level of moisture will vary from one refrigeration unit to the next and one condition the

next. The level of five to fifteen p.p.m. (parts per million) as mentioned previously has been used

as a guide line for many different types units.

5.5.5 LEAK TESTING

There are a number of causes of refrigerant leaks. Approximately 80% of all refrigeration system

service work will consist of checking for and/or locating and repairing leaks. Many leaks are

caused simply by vibration and threaded connection coming loose. Retightening these will solve

the problem. Component deterioration of hoses, seals, etc. may be a cause of leaks.

5.5.5.1 LEAK DETECTORS

The following types of leak detectors may be used to locate refrigeration system leaks:

1. Halide (propane) torch: one of the most commonly used, this leak detector uses a propane

flame, which draws the leaking refrigerant over a hot copper alloy reactor plate. A dramatic

color change in the flame will occur to show the presence of refrigerant (indicating a leak).

Figure 29 shows a leak testing operation using a halide (propane) torch.

45

2. Electronic detector: this instrument will draw in any leaking refrigerant through a

test probe, and then sound an alarm or create a flashing light if refrigerant is

found. It is the most sensitive of leak detectors used. Figure 30 illustrates an

electronic leak detector.

Figure 29LEAK TESTING

Figure 30 ELECTRONIC LEAK DETECTOR

46

3. Bubble detector: this is a solution applied externally at suspected leak points. Leaking

refrigerant will cause the detector to form bubbles and foam.

5.6 CLASS WORK ASSIGNMENT: UNIT FIVE

1. Figure 1 shows a cutaway view of _______________gauge.

a. Indicates the __________ _________________

b. Indicates the __________

c. Indicates the __________ _________________

d. Indicates the adapter __________

e. Indicates the calibration spring ______________ _________________

Figure 1

46





a. Indicates the __________ _________________


c. Indicates the __________ _________________



Figure 1

46





a. Indicates the __________ _________________


c. Indicates the __________ _________________



Figure 1

47

2. This kind of gauges are used to measure ______________inside the system. It must have

a ____________degree of _______________and good _________expectancy. In figure 2,

the _______________ and the ______________ are not showed.

3. Fins placed in a condenser coil aid in ________ distribution.

4. A __________ manifold ________ is shown in figure 2. It is a useful ________ for

service work.

a. is the compound gauge

b. is the low side seat

c. is the hand valve

d. is the low side port

e. is the service port

f. is the manifold

g. is the high side port

h. is the high side seat

i. is the high pressure gauge

Figure 2

48

5. Look at figure 3. High _________ cylinders are components of pressure __________

equipment. It is used for __________________, ______________ and

________________. They are filled with _______________under high _________.

a. Indicates the ____________ ____ _________________

b. Indicates the ____________ ____ _________________

c. Indicates the ____________ ____

d. Indicates the ____________ ____ _________________

e. Indicates the ____________ ____ _________________

Figure 3

6. List five safety precautions when handling pressurized cylinders of gas:

49

7. Look figure 4. It is a torch propane leak detector.

a. Indicates a ______________

b. Indicates the ______________

c. Indicates the ______________ ______________

d. Indicates the ______________

e. Indicates the ______________ ______________

f. Indicates the ______________ ______________

Figura 4

8. What is the leak detector most commonly used?

50

9. Figure 5 shows another _________detector. It is an ___________________leak

_____________. This instrument is the most __________of the leak _____________.

a. Is the ____________ ____________ ____________

b. Is the ____________ ____________ ____________

c. Is the ____________ ____________

d. Is the on____________ ____________ ____________

Figure 5

51

6. DISCUSIÓN

La elaboración de un texto de cualquier materia especialmente el de Inglés Técnico para

Estudiantes de Ingeniería en Energía, es un proyecto por demás ambicioso, el presente texto

ofrece el tema de Refrigeración por lo que no podrá satisfacer a plenitud las aspiraciones y

exigencias del lector en otros temas. No obstante, el presente texto constituye un intento por

complementar y contribuir a la adquisición de conocimientos de la formación académica de

nuestros estudiantes universitarios en Ingeniería.

52

7. REFERENCIALES

1. KENNETH WARK. DONALD RICHARDS. Termodinamica. Madrid: Mc. Graw Hills. 6ta.

Edicion. 2001.

2. ROZZ, LOUIS.Engineer´s Dictionary spanish – english and english–Spanish, Cesca,.5ta. Edicion 2005

3. YUMUS A. CENGEL. MICHAEL A. BOLES. Termodinamica. ,Mexico: Mc. Graw Hills. 6ta.

Edicion. 2009.

53

8. APENDICE

ENGLISH – SPANISH GLOSSARY

ABSOLUTE ZERO Puntoen el cual hay ausencia absoluto de

calor,equivalente 459° F bajo cero.

ACCURACY Precisión, exactitud

ACTUAL Real

ADAPTER Adaptador

ADVANTAGE ‘Ventaja

AIR CONDITIONER Equipo de aire acondicionado

ALUMINUM Aluminio

ASSEMBLY Conjunto, la unidad completa

BACKWARD Haciaatrás

BEARING Cojinete

BLOWER Soplador

BOILING POINT Es la temperatura a la cual un liquido cambia a vapor.

BOTTOM Parte baja inferior

BOURDON TUBE Tubo Bourdon

BTU Unidad de medida de cantidad de calor. Un BTUes

lacantidad de calor necesario para elevar un grado

Fahrenheit a una libra de agua a nivel del mar.

BUBBLE Burbuja

CALORIE Caloría, unidad de medida de cantidad de calor

CAP Tapa

CAPACITY Capacidad

54

CAPILLARY TUBE Tubo capilar

CARE Cuidado

CAST IRON Hierro fundido

CENTRIFUGAL COMPRESSOR Compresor centrifugo

CLEAR Claro, despejado

CLOCKWISE Sentido horario

CLOUDY Nublado

CLUTCH Embrague

COIL Bobina

COMPOUND PRESSURE Manómetro usado en el lado de baja presión.

GAUGE Registra presión manométrica y vacio.

COMPRESOR Compresora

CONDENSATION Condensación

CONDENSER Condensador

CONDUCTION Tipo de transmisión de calor a través de una sustancia.

CONNECTING ROD Biela

CONVECTION Tipo de transmisión de calor por medio de la circulación

de un líquido o gas.

COOLER Enfriador

COUNTERCLOCKWISE Sentido anti horario

CRANKCASE Alojamiento del cigüeñal

CUTAWAY VIEW Vista en corte

CYLINDER HEAD Culata

CHAMBER Cámara

CHECK VALVE Válvula que permite el paso de fluido en una sola

.Dirección, no permitiendo que retorne.

55

DAMAGE Daño, deterioro

DANGER Peligro

DEGREE Grado

DEHYDRATION La acción de sacar la humedad de un sistema de

refrigeración o producto.

DENSITY Densidad

DESICCANT Agente que sirve para absorber la humedad, usado en

sistema de refrigeración

.DEVICE Aparato, dispositivo, artefacto

DIAPHRAGM Diafragma

DIFFERENTIAL PRESSURE Presión diferencial

DIRT Suciedad

DISCHARGE Descarga

DOWNWARD Hacia abajo

DRIER Secador, elemento que quita la humedad

EARTH Tierra

ECONOMIZER Economizador

EFFICIENCY Eficiencia, rendimiento

ENOUGH Suficiente

ENVIRONMENT Medio Ambiente

EVAPORATION Cambio de estado de liquido a vapor

EVAPORATOR Evaporador

EXPANSION THERMOSTATIC VALVE Válvula de expansión termostática

FACTORY Fabrica

FAILURE Falla

FAN Ventilador

56

FIN Aleta

FITTING Unión, conexión

FLASHING LIGHT Luz intermitente

FLEXIBLE COUPLING Acople flexible

FLOAT Flotador

FLYWHEEL Volante

FOAM Espuma

FOREIGN OBJECTS Objetos extraños

FREEZING Cambio de estado de liquido a solido

FURNACE Estufa

FUSE Fusible

GASKET Empaquetadura

GEAR Engranaje

HAND VALVE Válvula manual

HAZARD Peligro

HEAT Calor

HEAT EXCHANGER Intercambiador de calor

HEAT INTENSITY Intensidad de calor, temperatura

HEAT QUANTITY Cantidad de calor

HERMETIC SEALED COMPRESSOR Compresor sellado

HIGH PRESSURE GAUGE Manómetro de alta presión

HIGH SIDE Lado de alta

HOLLOWED SHAFT Eje hueco por el centro

HOSE Manguera

HUB Parte central, núcleo

HYDRAULIC LOCK-UP Agarrotamiento hidráulico

57

ICE Hielo

IMPELLER Impelente, impulsor

INLET Lugar de acceso, entrada

INNER DIAMETER Diámetro interior

INPUT Lo que entra

INSULATION Aislamiento

KIND Clase, tipo

LATENT HEAT Fuga, escape no controlado

LEAK DETECTOR Detector de fugas

LENGTH Longitud

LIFE EXPECTANCY Expectativa de vida

LINK Nexo, unión, conexión

LOAD Carga

LOW SIDE Lado de baja

MACHINE Maquina

MAINTENANCE Mantenimiento

MANIFOLD Múltiple, colector

MANUFACTURER Fabricante

MEANS Medio

MEASUREMENT Medición

MELTING POINT Punto de fundición

MIST Mixtura, mezcla pulverizada

MIXTURE Mezcla

MOISTURE Humedad

OIL STREAKS Líneas de aceite

OIL SUMP Cárter, sumidero

58

OUTER DIAMETER Diámetro exterior

OUTLET Lugar de egreso, salida

OUTPUT Lo que sale

OVERCHARGED Sobre cargado

PASSAGE Pasaje, conducto

PIPING Tubería

POINTER Puntero

PORT Lumbrera

POSITIVE DISPLACEMENT Desplazamiento positivo

PRESSURE DROP Caída de presión

PRESSURE GAUGE Manómetro

PROCEDURE Procedimiento

PROCESS Proceso

PSI Libras por pulgada cuadrada

PUMP Bomba

PURGING Purgado

QUALITY Calidad

RADIATION Radiación

RATE Régimen, proporción

READING Lectura

RECEIVER Receptor, Acumulador

RECIPROCATING COMPRESSOR Compresor alternativo

REED VALVES Válvulas de lengüeta

REFRIGERANT Refrigerante

RING Anillo

ROTARY COMPRESSOR Compresor rotativo

59

ROTOR Rotor, eje giratorio

SAFE LEVEL Nivel seguro

SALT Sal

SCREEN Rejilla, pantalla

SEA LEVEL Nivel del mar

SEAL Sello

SENSIBLE HEAT Calor sensible

SERVICE FITTINGS Conexiones de servicio

SHAF Eje

SIDE VIEW Vista lateral

SIGHT GLASS Dimensión, talla, tamaño

SLEEVE Manguito

SPRING Resorte

STAGE Etapa

STEEL Acero

STEM Vástago

STROKE Carrera

SUBSTANCE Substancia

SUCTION Succión

SUN LIGHT Luz solar

SUPERHEATED VAPOR Vapor sobrecalentado

SYMTOM Síntoma

TEMPERATURE Temperatura

THERMAL PROTECTOR Protector térmico

THERMO BULB Bulbo sensor de temperatura

THROUTH A través, por medio

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TOP Parte de arriba

TYPE Tipo

UPWARD Hacia arriba

“V” BELT Faja en V

VACUUM Vacio

VALVE PLATE Placa de válvulas

VANE Alabe, paleta

VESSEL Envase, embarcación

VISCOSITY Viscosidad

WARM Caliente

WAVE Onda, ola

WAY Camino vía, medio

WEAR Desgaste

WEIGHT Peso

WHEEL Rueda, volante

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