Domestic Lpg Refrigerator

8/11/2019 Domestic Lpg Refrigerator

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DOMESTIC LPG REFRIGERATOR

ABSTRACT

Domestic refrigerators annually consume approximately 17,500 metric

tons of traditional refrigerants such as Chlorofluorocarbon (CFC) and

Hydroflourocarbon (HFC) which contribute to very high Ozone Depletion

Potential (ODP) and Global Warming Potential (GWP). Good progress is being

made with the phase out of CFC 22 from new equipment manufacture by

replacing LPG since it possesses an environmentally friendly nature with no ODP.

LPG is expected to results in comparable product efficiencies based on itscharacteristics. Therefore, this two types of refrigerants (LPG and CFC 22) to be

examined using a modified domestic refrigerator in term of their performance

characteristics parameters such as pressure and temperature at specified

location at the refrigerator and the safety requirements while conducting the

experiment. Based on the present work, it is indicate that the successful of using

LPG as an alternative refrigerant to replace CFC 22 in domestic refrigerators is

possible by getting LPG COP as 13 compared to 10 for CFC22 .

INTRODUCTION

In India, more than 80% of the domestic refrigerator utilize HFC 134a asrefrigerant, due to its excellent thermodynamic and thermo physical properties.But, HFC 134a has a high global warming potential (GWP) of 1300. There is a

need of assess various refrigerant option considering the existing refrigerators inthe field and for the future market.

CFCs a re principally destroyed by ultraviolet radiations in thestratosphere; the chlorine released in the high stratosphere catalyzes thedecomposition of ozone to oxygen; and ultraviolet radiations penetrates tolower altitudes. Credible calculations of the magnitude of the effect (Hoffman1987) and his team predicted 3% global ozone emissions of 700 thousand


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Combustion : The combustion of LPG produces carbon dioxide (CO2) andwater vapour but sufficient air must be available. Inadequate appliancesflueing or ventilation can result in the production of carbon monoxide

which can be toxic.

Vapour Pressure: LPG is a stored as a liquid under pressure. It is almostcolourless and its weight is approximately half that of an equivalentvolume of water. The pressure inside a closed container in which LPG isstored is equal to the vapour pressure of the liquid and corresponds to itstemperature.

Ignition Temperature: The temperature required to ignite LPG in air isaround 500 C.

Calorific Value: The calorific value of LPG is about 2.5 times higher thanthat of main gas so more heat is produced from the same volume of gas.

Toxicity : LPG is a colourless, odourless and non-toxic gas. It is suppliedcommercially with an added odorant to assist detection by smell.LPG isan excellent solvent of petroleum and rubber product and is generallynon-corrosive to steel and copper alloys.

Safety : LPG is just as safe as any other fuel. In fact, it is safer than mostfuels because neither LPG itself nor the end products that are producedby burning LPG in a suitable appliance are poisonous to inhale. Since LPGcannot burn without air, there can never be a Flash -back into thecylinder.

You can feel safe with LPG as the most through precaution are taken

to ensure your safety. All you have to do is to handle it correctly whilst adheringto the simple instructions provided.

Propane : suitable for use in all conditions. It is the onlyLPG product suitable for cold climates (such as the UK andCanada) because of its low boiling point of -43.6 F

(-42 C).


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Butane : suitable for use in hot climate only because of itshigher boiling point of 22.9 F (-5 C).

Propane/Butane mixtures : suitable for use in moderate

Climates

THE LPG REFRIGERATION CYCLE

i. LPG Gas Cylinder : The LPG gas cylinder, LPG flows through the pipe andreaches to the capillary tube. LPG gas pressure is approximate 80-100 psi.

ii. Capillary Tube :As the capillary tube, capillary tube downs the pressure up

to less than 1 psi.

iii. Evaporator :In the evaporator LPG is converted into the vapour from withlow pressure. After passing through the evaporator low pressure andtemperature LPG vapour absorbs heat from the chamber system.

iv. Gas Burner :After performing the cooling effect, low pressure LPG gas goesinto the burner where the burns.

PARTS OF REFRIGERATORS

LPG GAS CYLINDER

LPG is Liquefied Petroleum Gas. This is general description of Propane (C3H8)and Butane (C4H10), either stored separately or together as a mix.This is because these gases can be liquefied at a normal temperature byapplication of a moderate pressure increases, or at normal pressureby application of LPG using refrigeration. LPG is used as a fuel for domestic,industrial, horticultural, agricultural, cooking, heating and dryingprocesses. LPG can be used as an automotive fuel or aspropellant for aerosol, in addition to other specialist applications. LPGcan also be used to provide lightingthrough the use of pressure lanterns.

CAPILLARY TUBE


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The capillary tube is the commonly used throttling device in the domesticrefrigeration. The capillary tube is a copper tube of very small internaldiameter. It is of very long length and it is coiled to several turnsso that it would occupy less space. The internal diameter of thecapillary tube used for the refrigeration applications varies from 0.5

to 2.28 mm (0.020 to 0.09 inch). The capillary tube is shown inpicture. When the refrigerant enters in the capillary tube, its pressuredrops down suddenly due to very small diameter. The decrease in pressure ofthe refrigerant through the capillary depends on the diameter of capillary andthe length of capillary. Smaller is the diameter and more is the length of capillarymore is the drop in pressure of the refrigerant as it passes through it.

EVAPORATOR

The evaporators are another important parts of the refrigeration systems. Itthrough the evaporators that the cooling effect is produced in the refrigerationsystem.It is in the evaporators when the actual cooling effect takes place inthe refrigeration systems. For many people the evaporator is the main part ofthe refrigeration system, consider other part as less useful. The evaporatorsare heat exchanger surface that transfer the heat from the substance tobe cooled to therefrigerant, thus removing the heat from the from the substance. Theevaporators are used for wide variety of diverse application inrefrigeration and hence the available in wide variety of shape, sizesand designs. They are also classified in different manner depending on themethod of feeding the refrigerant, construction of the evaporator, direction ofair circulation around the evaporator, application and also the refrigerantcontrol.

In the domestic refrigerators the evaporators are commonly known as freezerssince the ice is made in these compartment.

In the evaporators the refrigerant enters at very low pressure andtemperature after passing through the capillary tube. This refrigerant absorbsthe heat from the substance that is to be cooled so the refrigerant

gets heated while the substance gets cooled. Even after cooling the substancethe temperature of the refrigerant leaving the evaporator is less than thesubstance.

In the large refrigeration plants the evaporator is used for chilling water. In suchcases shell and tube type of heat exchanger are used as the evaporators. Insuch plants the evaporators are classified as:


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(1). Dry expansion type of evaporators(2). Flooded type of the evaporators

The evaporators are classified based on the construction as:

(1). Bare tube evaporators(2). Plate surface evaporators(3). Finned evaporators(4). Shell and tube evaporator(5). Shell and coiled evaporator, and(6). Tube-in-tube evaporator

The evaporators are classified based on mode of heat transfer

(1). Natural convection evaporator, and

(2). Forced convection evaporator

The evaporators are classified based on operating conditions

(1). Frosting evaporator,(2). Non-frosting evaporator, and(3). Defrosting evaporator

PRESSURE GAUGES

Many techniques have been developed for the measurement of pressureand vacuums. Instruments used to measure pressure are called pressure gaugesor vacuum gauges.A manometer could also referring to a pressuremeasuring instrument, usually limited to measuring pressures near toatmospheric. The term manometer is often used to refer specifically to liquidcolumn hydrostatic instruments.

STAINLESS STEEL PRESSURE GAUGE

Catering to the requirements of to power and allied Industry, we offerquality array of stainless steel, weather proof pressure gauges.Renowned for offering resistance in corrosive environments and modes, thesefind wide application in power generation, pollution control equipment,chemicals and petrochemicals and also exploration. These gaugesare available in 63mm, 100mm, and 150mm sizes and can be customized as perclient.


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BOURDON GAUGE

A Bourdon gauge uses a coiled tube, which, as it expands due to pressureincreases cases a rotation of an arm connected to the tube.In 1849 theBourdon tube pressure gauge was patented in France by Eugene Bourdon.The pressure sensing element is a closed coiled tube connected tothe chamber or pipe in while the pressure is to be sensed. As the gaugepressure increases the tube will tend to uncoil, while a reduced gaugepressure will patented France by Eugene Bourdon.

The pressure sensing el cause the tube to coil more tightly. This motion istransferred through a linkage to a gear train connected to an indicatingneedle. The needle in presented in front of a card face inscribed with thepressure indications associated with particular needle deflections. In abarometer, the Bourdon tube is sealed at both ends and the absolute pressureof the ambient atmosphere is sensed. Differentials Bourdon gauges use twoBourdon tubes and a mechanical linkage that compares the readings.

HIGH PRESSURE PIPES

The range of high pressure pipes covers most application where there is arequirement to transfer gas at high pressure. They consist of a steel pipe witha steel ball fitted to both ends. Two swivelling connection nipplespress these balls against the seating of the connecting hole andthus sealing against gas leakage Wide range of pipes. All pipes are pressure tested to 100 M Pa (14,500 psi) overrecommended working pressure.

CONSTRUCTION OF THE LPG REFRIGERATOR

The LPGrefrigerator shown in figure. We make the one box of the plywood. Theplywood sheet size is 12mm for used the LPG refrigerator. The size of therefrigerator is 724*457*381 mm3. The evaporator is fitted on the upper portion ofbox inside.


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Inside the refrigerator, we also put the thermo-coal sheet, because of the coldair cannot the transfer from inside to outside of refrigerator.

Fig 3.1 :- Construction of the LPG refrigerator

The schematically diagram of the LPG refrigeration system is shown in nextpage. The gas tank is connect by pipes to the capillary tube. The capillary tubeis fitted with evaporator. The evaporator coiled end is connect to the stove byanother gas circulation pipe. When two pressure gauge is put between capillarytube and gas tank, and another is put the end of the evaporator.WORKING LPG REFRIGERATOR

The basic idea behind LPG refrigeration is to use the evaporation of a LPG toabsorb heat. The simple mechanism of the LPG refrigeration working is shown infigure.


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Fig 3.2 Working of LPG Refrigerator

LPG is stored in the LPG cylinder under high pressure.

When the gas tank of regulators is opened then highpressure LPG passes in gas pipe. This LPG is going byhigh pressure gas pipe in capillary tube.

High pressure LPG is converted in low pressure atcapillary tube with enthalpy remains constant.

After capillary tube, low pressure LPG is passed throughevaporator. LPG is converted into low pressure andtemperature vapour from and passing through the

evaporator which absorbs heat from the chamber. Thusthe camber becomes cools down. Thus we can achievecooling effect in refrigerator.

After passing through the evaporator low pressure LPGis passed through pipe by burner. And we can uses thelow pressure of LPG is burning processes.


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CAUSES AND PRECAUTION

Explosion in space Any refrigerant with vapour pressure above ambientcan flash to a larger volume. The potential increase in volume is greater ifcombustion of lubricant or refrigerant occurs. Explosion venting may be

necessary to limit pressure rise to what the space can safely withstand. 2kPa can blow window glass off a building.

Fire Combustible lubricant and refrigerant must be discharged safelyoutside a building when a fire occurs especially if the heat of combustionexceeds 200 MJ.

Asphyxiation or poisoning All refrigerants except air and oxygen areasphyxiations. Ventilation must prevent serious injury or death on a suddentotal release of refrigerants. The quantity of ventilation necessary varies

greatly between refrigerants. Flying metal System must comply with piping and pressure vessels codes.

Corrosion or chemical reaction LPG refrigerants are non-reactive andchemically stable at refrigeration temperature.

Chemical or cold burns Accidental contact between skin and cold metalmust be prevented by insulation. Accidental releases of liquid refrigerantmust drain safely.

ADVANTAGE OF LPG

The advantages of LPG are as follows :

Clean burning. Effects of corrosions are greatly reduced. Instantly control the flame temperature. Avoids scaling and decarburising of parts. Environmentally friendly fuel, with minimal sulphur


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content and sulphur-free emissions. Very high efficiency with direct firing system instant heat for faster warm-up and cool-down. LPG is easily liquefied and stored in pressure containers. It can be easily transported in cylinder or tanks.

ADVANTAGES:

The cooling capacity of LPG is 10% higher than R-12 and the vapourpressure is appropriate.

LPG is naturally occurring and non-toxic. Use of LPG as a refrigerant also improves the overall efficiency by 10 to

20%. The ozone depletion potential (ODP) of LPG is 0 and Global warming potential (GWP) is 8 which is Significantly negligible as compared to other refrigerant. Apart from environment friendly, use of also LPG gives us lot of cost

advantages. LPG does not form acids and thereby eliminates the problem with

blocked capillaries. There is 60% reduction in weight of the system due to higher density of

LPG. The fridge works when electricity off. It is efficient to save fuel.

No pollution The units are effectively silent in operation. Running cost is zero. Eliminates the compressor and condenser.

DISADVANTAGES:

LPG is explosive in nature. Do not maintain constant pressure in LPG cylinder. Put the LPG cylinder is inverted position. After the refrigeration processes, the exhaust of LPG is burn into burner.

Because of the exhausted vapour LPG


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cannot converted again liquid phase , because the this process is verycostly.

The prevention of leakage of the LPG is the major problem in LPGrefrigeration system. Because of the LPG is highly flammable.

CONCLUSION :

After performing this project LPG Refrigeration, we conclude that refrigerationeffect is produced with the use of LPG.

From observation table, we conclude that, the regulating valve is fully openthat, we achieve the chamber temperature down from 38C to 10C in a 100minute. We achieve the evaporator temperature down from 1C to -9.3C in asame time interval.

We put the water in one plastic bottle in the evaporator. The initialtemperature of water is 35 C. From observation table, we conclude that, thecondition of regulating valve is fully opened, the same time period we achievethe temperature of water is 0.30 C.

We also conclude that, the capillary tube is maximum pressure of gas cylinderis reduces the less then of 1 psi. The capillary tube is more suitable throttlingdevice in LPG refrigeration system.

This system is cheaper in initial as well as running cost. It does not require anexternal energy sources to run the system and no moving part in the system somaintenance is also very low.

We also conclude that, we try the burnt to the exhaust LPG, the pressure ofexhaust gas is less than 1 psi, the small flame produce by the burner.

This system most suitable for hotel, industries, refinery, chemical industries whereconsumption of LPG is very high.

BIBLIOGRAPHY :

http://www.hychill.com.au/pdf/pasolpgr.pdf www.e-lpg.com http://www.google.com/g www.dynatempintl.com www.lpgforyou.com http://www.brighthub.com/engineering/mechanical.aspx


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http://coolingdevice.net/4.html http://howstuffworks.com/refrigerator.htm www.indiamart.com A Textbook of Refrigeration and Air Conditioning by R.S.KHURMI &

J.K.GUPTA

Performance and safety of LPG Refrigerant , The University of New SouthWales, Australia.

Applications of Refrigeration & Air Conditioning, Lesson 3, Version 1 ME,IIT Kharagpur 1

A Textbook of Thermal Engineering, By R.S.KHURMI & J.K.GUPTA Arora , C.P, Refrigeration & Air Conditioning, Tata McGraw Hill Company

Limited, New Delhi.

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Domestic Lpg Refrigerator