TECH HUB

what is Refrigerant

2019-10-23T02:15:00.000-07:00

It absorbs the heat in one place by absorbing it into another system by means of a source .

This is called refrigerant. It consists of evaporation and condensation, which absorbs heat

and produce cooling .

The following are the characteristics of a refrigerant.The first of the characteristics of a

refrigerant is that the refrigerant should not be poison . It may not have acidic
properties at all.

It does not rust like iron, so the oil does not absorb in it. Chemicals do not react to it.
Not involved in reaction with different materials.

The point of this should be to minimize feed and space specific volume.
They can absorb as much heat as they can when converted into cooling.

The following are the types of refrigeration:

R 22 a

It is a refrigerant of the Freon Group. At 5 Fahrenheit it is indicated by raisingits pressure head.The operating pressure of the head is 60 to 80 pounds per square inch

and the discharge pressure is 210 to 280 pounds square inches.

R 134 a It is a refrigerant of the Freon Group .

At normal air pressure, its boiling point is 26.5 degrees Fahrenheit, its critical temperature is
101.4 degrees Celsius, the gas is environmentally friendly.

Used in deep freezer and watercolor.

R 404

It is a refrigerant of the Freon Group.Refrigerant 404 is an environmentally friendly refrigerant.

It is made from the formula of R-134 ,R-115 and R-122 trio. It is less poisonous and never fires.
It is colorless. Used in most air conditioners. Its cylinder color is orange. Feel the point at
normal air pressure and 46.5 is five negative centigrade.

Its critical temperature is 5 degree centigrade.

R 410

It is a refrigerant of the Freon Group.It is being used a lot in the refrigerant industry,
its normal air pressure and boiling point is -48.5, its credit pressure is 4.86, its melting
point is 155 degrees centigrade,which does not affect the ozone.

This gas is ozone friendly. It is used for refrigerator deep freezer and refrigerator
water coolers,

as well as for various purposes. Also used in air conditioning

R-502

It is a refrigerant of the Freon Group. It is a mixture of two gases.

Its boiling point at negative pressure is negative 49. its critical temperature.

The color of this cylinder is purple and is used in commercial units.

R-717

It is a refrigerant of the Freon Group .

Its chemical names are ammonia. NH 3

It is second-class poisonous gas. It has a chemical formula. Used for purposes and
used in ice cream maker unit. Smelling it in large quantities also makes man unconscious.
With this, water cooled condensers are used.

hydraulic intensifier

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A hydraulic intensifier is a hydraulic machine for transforming hydraulic power at low pressure into a reduced volume at higher pressure.

Explanation and Working

Such a machine may be constructed by mechanically connecting two pistons, each working in a separate cylinder of a different diameter. As the pistons are mechanically linked, their force and stroke length are the same. If the diameters are different, the hydraulic pressure in each cylinder will vary in the same ratio as their areas: the smaller piston giving rise to a higher pressure..As the pressure is inversely proportional to the area, it will be inversely proportional to the square of the diameter.The working volume of the intensifier is limited by the stroke of the piston. This in turn limits the amount of work that may be done by one stroke of the intensifier.These are not reciprocating machines (i.e. continually running multi-stroke machines) and so their entire work must be carried out by a single stroke. This limits their usefulness somewhat, to machines that can accomplish their task within a single stroke.

Applications

They are often used where a powerful hydraulic jack is required, but there is insufficient space to fit the cylinder size that would normally be required, for the lifting force necessary and with the available system pressure.Using an intensifier, mounted outside the jack, allows a higher pressure to be obtained and thus a smaller cylinder used for the same lift force. Intensifiers are also used as part of machines such as hydraulic presses, where a higher pressure is required and a suitable supply is already available

Intensifiers with Stepped Piston

Some small intensifiers have been constructed with a stepped piston. This is a double-ended piston, of two different diameters, each end working in a different cylinder.This construction is simple and compact, requiring an overall length little more than twice the stroke. It is also still necessary to provide two seals, one for each piston, and to vent the area between them.A leak of pressure into the volume between the pistons would transform the machine into an effective single piston with equal area on each side, thus defeating the intensifier effect.

Concentric cylinder hydraulic intensifier

A mechanically compact and popular form of intensifier is the concentric cylinder form, as illustrated. In this design, one piston and cylinder are reversed: instead of the large diameter piston driving a smaller piston, it instead drives a smaller moving cylinder that fits over a fixed piston.This design is compact, and again may be made in little over twice the stroke. It has the great advantage though that there is no "piston rod" and the effective distance between the two pistons is short, thus permitting a much lighter construction without risk of bending or jamming.

Shock Absorbing Characteristics

Types Commonly used Accumulators

there are three different types of accumulator Commonly used.

Hydraulic Accumulator

"A type of power storage devices,functioning as a temporal storage tank of fluid energy to provide or absorb momentary flow".

An accumulator can serve as

an auxiliary power source,

a pulsation absorber,

a shock damper,

a leakage makeup source, and

a thermal expansion compensator

Functions of an Accumulator

Energy storage

Pulsation absorption

Shock cushioning

Supplementing pump flow

Maintaining pressure

Fluid dispensing

Spring Loaded Accumulators

In a spring loaded accumulator, a change in fluids volume is proportional to its pressure.

As the spring compression increases as fluid enters the chamber and decreases as the accumulator is discharged, the pressure is not constant.

Gas Charged Accumulators

In a closed chamber, a change in gas volume must result in an identical fluids volume. It can maintain a constant fluid pressure.

Six Stages of Operation

empty - no gas charge
precharged with dry nitrogen
system pressure exceeds precharge pressure, and hydraulic fluid flows into accumulator.
system pressure peaks, maximum fluid has entered accumulator, and system relief opens
system pressure drops, precharge pressure forces fluid from accumulator and into system
system pressure reaches

Sizing Accumulators

Hydraulic accumulators are normally sized in terms of specific applications. For example

CPU , MEMORY AND PROCESSING

2019-10-04T03:09:00.001-07:00

MEMORY & PROCESSING UNIT.

the microprocessor is processing unit also called the CPU.

CPU stands for central processing unit ,it carries out all information which computer operate .

RAM

word Ram stands for (Random Access Memory) which is directly accessible by the CPU. Ram available in different size in market such as 128 Mb,256 MB,512 MB ,1 GB to 64 GB.

ROM

Rom is used for read only memory .in ROM instruction given which could not be deleted.this could be read only and when computer start its beginning instruction deeded in Rom.

DIFFERENCE BETWEEN RAM AND ROM

Difference between ram and ROM is given below in figure.1

TYPES OF COMPUTER

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there are three types of computer with respect to operation Principle

Analogue Computer
Digital Computer
Hybrid Computer

Classification of Digital Computer

(by speed & size)

computer are mainly classified into four categories based upon there process speed,size and storage capacity.

Microcomputer
Mini computer
mainframe computer
Super computer

1.Micro Computers

micro computer are commonly know as personal computer .these are small computers that are found in office ,school,homes.they have microprocessor chip as the CPU in it.

2.Mini computer

Mini computers they have large storage capacity and more processing Speed then microcomputer.The are used in Multi user environments.where more the one person is working on computer at same time.

3. Mainframe Computer

Mainframe computer are more powerful than mini computer.thy are large and very expansive computer that can handle more users.

4.Super computer

Super computer are the most powerful and expensive computer.

the are built to solve complex scientific calculation

the are used for weather forecasting ,nuclear research ,monitoring of Satellites etc.

5.Supercomputer

Supercomputer center to the elite top 200 list of super computing site in the world .

Computer Input Output Devices

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INPUT DEVICES

Keyboard
Mouse
Scanner
Microphone
Camera
touch pad

OUTPUT DEVICES

Monitor
Head Phone
speaker
Printer

Computer science

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Data

A collection of facts and figures is called data .Data is given to the computer for processing. Data is collected from different sources. Data may consist of numbers,characters ,symbols or picture etc.

Data Information

The processed data is called information.information is an organized and processed from of data.

Data process

The process of converting data into information is called processing.Data is the input and information is the output of data processing system.it is known as computing.

Input

Processing

Output

Example

Software

A set of instructions given to the computer to solve different problem is called software.

Hardware

the physical parts of the computer is called hardware.

Refrigeration Definitions

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Absorption Refrigeration

One refrigeration process that uses heat transfer (thermal)driving force to utilize the refrigerant.

Accumulator

a storage vessel for liquid refrigerant ,Also known as surge drum.

Bubble point

the temperature at which the vapor pressure of the liquid refrigerant equals the absolute external pressure of the liquid vapor interface

what is Two Stage System refrigeration system

2019-09-26T11:22:00.002-07:00

Refrigeration systems utilizing one, two, three, or four stages of compression have been

successfully operated in various services. The number of levels of refrigeration generally

depends upon the number of compression stages required, inter stage heat loads,

economics, and the type of compression.

i. One-Stage System

A typical one-stage refrigeration system is shown in Fig. 7 where the data are for pure

propane refrigerant.

Two-Stage System

A two-stage refrigeration system and inter stage flash economizer can savings in the range

20%. Also removing process heat at the inter stage level rather than at the low stage level.

A typical two-stage system with an intermediate load is shown in Fig. 8 with data for pure

propane.

Steam Jet Refrigeration

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The steam-jet refrigeration system could be defined as a thermally drive compression

system in which vapor is compressed in a jet apparatus. An example of this operation

illustrated in Figure 6.

Steam is generated at pressure p1 in boiler and the mass flow rate is m1. By using the

nozzle, the steam is expanded to the pressure p0 prevailing in the evaporator, then it would

mixed with the steam from the evaporator in the mixing chamber. After that, the pressure

of the two streams is raised to the condensation pressure in the device called diffuser.

Virtually, all the kinetic energy is transformed into the pressure. When the heat is withdrawn

in the condenser, the steam will condenses.

The condensate is separate into two sub streams and it’s delivered to the steam boiler by a

driven force from a pump. Thus, one of the mass flow rate stream is led to the evaporator

through an expansion valve. Here, the sub stream evaporates and absorbing the heat, and

then exiting expanded steam, moving at a higher velocity, sucks this stream into the mixing

chamber.

Water, mainly employed as a working steam and also as refrigerant in the steam-jet

refrigeration system. It is a low-cost, free of hazard, having a high specific enthalpy of

evaporation. The pressure p0 operates usually between 0.6 until 1.2 kPa, while pc operates

between 3 until 8 kPa, depending on the cooling-water temperature.

The steam-jet refrigeration is suited for many applications such as :

1. Direct vaporization for heat-sensitive foods and chemicals drying. Mostly, for

preservation of the product quality.

2. Absorption of gases like CO2, SO2, ClO2 in chilled water.

Assuming the water greater than 35°F is needed and that water and stream costs are

reasonable, there are several advantages of steam jet units that could be achieved

following :

1. No moving devices, except the pumps.

2. Low pressure system.

3. Compact design and could be installed on the outdoors.

4. Economical process, since the cooling water and steam could easily be adjusted.

5. Low maintenance and Vibration-free.

6. Simple start up and operation.

7. Cost per ton of refrigeration is relatively low.

Absorption Refrigeration

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Absorption refrigeration is a form that is economically attractive when there is a source of
thermal energy at a temperature between 100 to 200°C. An example of inexpensive thermal
energy sources are, solar energy, waste heat from co generation or process steam plants,
geothermal energy, and natural gas when available at a low price.
The absorption refrigeration involve the absorption process of a refrigerant by a transport
medium called absorbent to form a liquid solution. The liquid solution the pumped to the
higher pressure. Due to the average specific volume of the liquid solution is much less than
of the refrigerant vapor , significantly less work is needed. Accordingly, absorption
refrigeration system have the advantage of relatively small work input compared to vapor-
compression system.
Absorption refrigeration systems differ from compressor refrigerating systems at least in
two major aspects :
1. The refrigerant drawn out of the evaporator is compressed not by a mechanical
process, but by a thermal heat-exchange which consists of an absorber, a generator,
and a pump.
2. Operation of thermal compressors requires a solvent (for a second working fluid) as
well as refrigerant.
Two most generous industrial absorption-type refrigeration systems are :
1. Aqua ammonia system.
2. Lithium bromide-water system.
Both of the system respectively used ammonia and water as the refrigerant. Ammonia –
water is used for evaporating temperature on the range -60 until 10°C, while water-lithium
bromide is used for evaporating temperatures more than 0°C. No other any pair
components had been suggested that widely used except the two of them. Figure 5
represents the basic absorption refrigeration system.

Types Of Refrigeration

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There are three types of Refrigeration which are give below

Mechanical Refrigeration system
Steam Jet Refrigeration
Absorption Refrigeration

The mechanical refrigeration used a Compressor, the Absorption and desorption process
used the thermal energy forces, while the Steam Jet process used pressure difference from
Ejector.
One of the most well-known refrigeration method for the mechanical refrigeration is Vapor-
Compressor Systems or sometimes also called Vapor-Compression Cycles. Isothermal
processes are realized through isobaric evaporation and condensation in the tubes. Figure
4 marked the standard vapor compression refrigeration cycle.
Work that produced in turbine is small. Therefore, the turbine equipment could be replaced
by an expansion valve for efficiency. Nonetheless, wet compression is substituted to an
compression vapor for the reasons of proper compressor function.

Pressure Definition

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Definition

force per unit Area is call pressure

P=F/A

unit Psi , Bar , K P A.

Psi Definition

pound square inch is called psi.

BAR Definition

metric system unit which is 14.50 bar per square inch at sea level.

Saturation Temperature

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The temperature at which a substance will change state from a liquid to a vapor or a vapor to a liquid to a liquid.

Add Heat =liquid to Vapor (vaporization)

Remove Heat = vapor to liquid (condensation)

Vapor Compression Cycle

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Vapor Compression Cycle is show in fig.1

Example:

REFRIGERATION System & Refrigeration cycle

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Generally, refrigeration is used for temperature requirements from 80 – 85 degree F to as near

absolute zero as the process demands. The petrochemical and chemical range does not go

much below -200 degree F. Refrigeration process consists of five component equipment, they

are

1. Compressor.

2. Evaporator.

3. Condenser.

4. Expansion Valve.

5. And Refrigerant.

A general equipment arrangement of Refrigeration cycle shows in Figure 1.

Fig 1

Refrigerant vapor enters the compressor suction and the compressor raises the refrigant

pressure so the saturation temperature is above the temperature of the available cooling

medium. This difference allows transfer of heat from the vapor to the cooling medium so

that the vapor can condense to a liquid. The condensed liquid then flows through the

expansion device such as expansion valve and flashes into a vapor, cooling the remaining

liquid refrigerant below the temperature of the product to be cooled.

This difference in temperature allows heat to be transferred from the product to the

refrigerant, causing the refrigerant to evaporate. The vapor formed must be removed by

the compressor at a rate sufficient to maintain the low pressure in the evaporator and keep

the refrigerant flowing. The resulting continuous flow process is referred to as the

refrigeration cycle, shown schematically in Figure 2. This cycle is also called the reverse

ranking cycle and is governed by the principles of thermodyanmics.

Fig 2.

Refrigeration Cycle

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Basic Refrigeration Cycle

What is heat?

A form of energy

What is cold?

Absences of heat.

How does heat flow?

High heat to low heat

Does cold flow?

NO...!

How is heat measured?

British Thermal Unit

B.T.U

Heat is a form of energy and is measured British in BTU’s.

Thermal Unit

A BTU is the quantity of heat required to

raise the temperature, of one pound of

(BTU) water, one degree Fahrenheit.

What is Heat ?

Heat flows from high energy levels to a lower energy level.
Heat will not flow with out a temperature difference
The greater the temperature difference, the faster the energy will flow.

Conduction

The transfer of heat from molecule to molecule through

Example:Heating one end of a copper tube a substance by

chain collision tube, will cause the other end to get hot. as shown in fig. (a,b)

fig a.

fig b

Convection

Heat transfer by the movement of molecules from

Example: Convection oven one place to

another.Forced air furnace. as shown in fig c

fig c .

Radiation

Radiation is vitality going through space.Sunshine is one of the most recognizable types of radiation. It conveys light, warmth and suntans. While getting a charge out of and relying upon it, we control our presentation to it.Beyond bright radiation from the sun are higher-vitality sorts of radiation which are utilized in prescription and which we as a whole get in low dosages from space, from the air, and from the earth and shakes.as shown in fig e

fig e.

Refrigeration System

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INTRODUCTION

Refrigeration maintains the temperature of the heat source below that of its surroundings

while transferring the extracted heat, and any required energy input to a heat sink,

atmospheric air or surface water. is a very important unit operation. During the 1990’s. it was estimated that

annual investment in refrigeration machinery and equipment exceeded $100 billion and the

value of the products treated by refrigeration exceeded $1 trillion.

Types Of Refrigeration

Types of refrigeration may be categorized within five abroad areas of application that touch

most of our daily lives:

1. Daily devices, like household refrigerator / freezers.

2. Commercial equipment systems in example of supermarket display, restaurants,

and cafeterias.

3. Food processing like refrigerated warehouse.

4. Industrial tools, in example of liquefaction of gases, chemical process cooling, and

crystallization.

5. Public Transportation (refrigerated truck or trailer and marine containers).

This Refrigeration design guideline covers the basic elements in the field of Refrigeration

Systems in detail to allow an engineer to design a Refrigeration System with the suitable

size of refrigeration needed, work input, coefficient of performance (COP), electric power

input and selecting refrigerant which is to be utilized. This design guideline includes design

of single stage, multi stage and cascade refrigeration systems.

Refrigeration System

A refrigeration system is a combination of components and equipment connected in a

sequential order to produce the desired refrigeration effect (cooling or heating).

Refrigeration maintains the temperature of the heat source below that of its surroundings

while transferring the extracted heat, and any required energy input to a heat sink,

atmospheric air or surface water.

The design of a Refrigeration System may be influenced by factors, including process

requirements, economics and safety.

TECH HUB

what is Refrigerant

R 22 a

R 404

R-502

R-717

hydraulic intensifier

Explanation and Working

Intensifiers with Stepped Piston

Concentric cylinder hydraulic intensifier

Spring Loaded Accumulators

CPU , MEMORY AND PROCESSING

TYPES OF COMPUTER

Classification of Digital Computer (by speed & size)

1.Micro Computers

2.Mini computer

3. Mainframe Computer

5.Supercomputer

Computer Input Output Devices

Computer science

Data

Data Information

Data process

Software

Hardware

Refrigeration Definitions

what is Two Stage System refrigeration system

Steam Jet Refrigeration

Absorption Refrigeration

Types Of Refrigeration

Pressure Definition

Definition

Psi Definition

BAR Definition

Saturation Temperature

Vapor Compression Cycle

Vapor Compression Cycle is show in fig.1

REFRIGERATION System & Refrigeration cycle

Refrigeration Cycle

Basic Refrigeration Cycle

B.T.U

Thermal Unit

What is Heat ?

Conduction

Radiation

Refrigeration System

INTRODUCTION

Types Of Refrigeration

Refrigeration System

Classification of Digital Computer

(by speed & size)