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  1. 1. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 1 CHAPTER 1 REFRIGERATION 1.1 INTRODUCTION The term ‘refrigeration’ in a broad sense is used for the process of removing heat (i.e. cooling) from a substance. It also includes the process of reducing and maintaining the temperature of a body below the general temperature of its surroundings. In other words, the refrigeration means a continued extraction of heat from a body, whose temperature is already below the temperature of its surroundings. For example, if some space (say in cold storage) is to be kept at - from cold body and delivers to a hot body. The substance which works in a heat pump to extract heat from a cold body and to deliver it to a hot body is called refrigerant. When people hear the word refrigeration they immediately think of the refrigerator in their kitchen. However there are actually quite a few 2 ºC, we must continuously extract heat which flows into it due to leakage through the walls and also the heat, which is brought into it with the articles stored after the temperature is one reduced to -2 ºC. Thus in a refrigerator, heat is virtually being pumped from a lower temperature to a higher temperature. According to second law of thermodynamics, this process can only be performed with the aid of some external work. It is thus obvious, that supply of power (say electrical motor) is regularly required to drive a refrigerator. Theoretically, the refrigerator is a reversed heat engine, or a heat pump which pumps heat different kinds of refrigeration out three and they each have their own methods of functioning. One particular type of refrigeration is industrial refrigeration. This type of refrigeration is typically used for cold storage, food processing, and chemical processing. The equipment is very large and made of industrial stainless that must maintain a constant and steady temperature at all times. Temperatures that are too high or too low may spoil certain goods or ruin them. As a result industrial refrigeration is especially important maintaining temperature is as well. Since temperature is so important into industrial refrigeration companies offering this service must pay attention at all times to the temperature of the industrial refrigerators.steel. Industrial refrigeration, which frequently uses ammonia refrigeration to maintain
  2. 2. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 2 temperature, is necessary for computer, foodstuffs, blood, vaccines, and quite a few other goods. 1.2 HISTORY OF REFRIGERATION The refrigeration system is known to the man, since the middle nineteenth century. The scientist, of the time, developed a few stray machines to achieve some pleasure. But it paved the way by inviting the attention ohine by the end of nineteenth century for the refrigeration jobs. But with the advent of efficient rotary f scientist for proper studies and research. They were able to build a reasonably reliable mac compressors and gas turbines, the science of refrigeration reached its present height. Hebrews, Greeks, and Romans placed large amounts of snow into storage pits dug into the ground and insulated with wood and straw. The ancient Egyptians filled earthen jars with boiled water and put them their roofs, thus exposing the jars to the night’s cool air. In India, evaporating cooling was employed. When a liquid vaporises rapidly, it expands quickly. The rising molecules of vapour abruptly increase their kinetic energy and this increase is drawn from the immediate surroundings of the vapour. These surroundings are therefore cooled. The intermediate stage in the history of cooling foods was to add chemicals like sodium nitrate or potassium nitrate to water causing the temperature to fall. Cooling wine via above method was recorded in 1550, as were the words “to refrigerate”. Cooling drinks came into vogue by 1600 in France. Instead of cooling water at night, people rotate long-necked bottles in water in which saltpetre had been dissolved. This solution could be used to temperature. Brewing was the first activity in the northern states to use mechanical refrigeration extensively, beginning with an absorption machine used by S. Liebmann’s Sons Brewing Company in Brooklyn, New York in 1870. commercial refrigeration was primarily directed at breweries in the 1870 and 1891, nearly every brewery was equipped with refrigerating machines. Natural ice supply became an industry unto itself. By 1879, there were 35 commercial ice plants in America, more than 200 a decade later, and 2,000 by 1909.
  3. 3. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 3 No pond was safe from scraping for ice production, not even Thoreau’s Walden Pond, where 1,000 tons of ice was extracted each day in 1847. However, as time went on, ice, as a refrigeration agent, became health problem. Says Bern Nagengast, co-author of Heat and Cold: Mastering the Great Indoors (published by the American Society of Heating, Refrigeration and Air-conditioning Engineers), “Good sources were harder and harder to find. By the 1890’s, natural ice became a problem because of produce very low temperature and to make ice. By the end of the 17th century, iced liquors and frozen juices were popular in French society. The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasow in 1748. Beginning in the 1840, refrigerated cars were used to transport milk and butter. By 1860, refrigerated transport was limited to mostly seafood and dairy products. The refrigerated railroad car was patented by J.B.Sutherland of Detroit, Michigan in 1867. He designed an insulated car with ice bunkers in each end. Air came in on the top, passed through the bunkers, and circulated through the car by gravity, controlled by the use of hanging flaps that created differences in airpollution and sewage dumping.” Signs of a problem were first evident in the brewing industry. Soon provided the solution: ice, mechanically manufactured, and giving birth to mechanical refrigeration. Carl (Paul Gottfried) von Linde in 1895 set up a large scale plant for the production of liquid air. Six years later the meatpacking and dairy industries followed with their complaints. Refrigeration technology he developed a method for liquid air separating pure liquid oxygen from that resulted in widespread industrial conversion to processes utilizing oxygen (e.g. in steel manufacture). 1.3 TYPES OF REFRIGERATION The difference types of refrigeration systems are given below.  Cyclic Refrigeration In the cyclic process of refrigeration the heat is removed from the low temperature reservoir and is thrown to high temperature. As per the second law of thermodynamics the natural flow of heat is from the high temperature to low temperature reservoir. In the cyclic refrigeration process since the flow of heat is reversed, the external work has to be done on the system.
  4. 4. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 4 The cyclic process of refrigeration is also reverse of the thermodynamic power cycle or Carnot cycle in which the heat flows from high temperature reservoir to low temperature reservoir; hence the cycle of refrigeration is also called as Reversed Carnot Cycle. There are two types of cyclic process of refrigeration:  Vapour cycle and  Gas cycle. The vapour cycle is classified into Vapour compression cycle and vapour absorption cycle.  Vapour Compression Cycle In a vapour compression system, an evaporator and a gas-liquid separator are received in a common casing, so that the gas-liquid separator and the of the liquid phase refrigerant from the atmosphere to reduce the heat evaporator are placed close to each other. Thus, it is possible to limit heart absorption loss upon discharge of the refrigerant from the gas- liquid separator. Also, it is possible to reduce pressure loss in refrigerant passage between the gas-liquid separator and the evaporator.  Vapour Absorption Cycle Before the development of the vapour compression system of refrigeration, vapour absorption system was very widely used. The vapour compression system replaced vapour absorption system because it has high coefficient performance (COP). The vapour absorption system requires very less amount of electricity but large amount of heat; hence it can be used very effectively in industries where very large stocks of excessive stem are available. In such cases there is not only effective utilization of steam, but also lots of savings in electricity costs.  Gas Cycle Just as the vapour are used for cooling in the vapour compression cycle and vapour absorption cycle, the gas is used cooling in gas refrigeration cycle. When the gas is throttled from very high pressure to lower pressure in throttling valve, its temperature reduces suddenly while its enthalpy remains constant. This principle is in gas refrigeration system. In the system instead of using Freon or ammonia as the refrigerant, the gas is used as the refrigerant.
  5. 5. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 5 Throughout the cycle there are no phase changes of the gas, which are observed in the liquid refrigerant. Air is the most commonly used gas, also called as refrigerant in this case, in the gas refrigeration cycles.  Non Cyclic Refrigeration In these methods, refrigeration can be accomplished by melting ice or by dry ice. These methods are used for small-scale refrigeration such as in laboratories and workshops, or in portable coolers.  Thermoelectric Refrigeration A refrigeration effect can also be achieved without using any moving parts by simply passing a small current through a closed circuit made up of two dissimilar materials. This effect is called Peltier effect, and a refrigerator that works on this principle is called a thermoelectric refrigerator.  Magnetic Refrigeration Magnetic refrigeration is a cooling technology based on the magneto caloric effect. This technique can be used to attain extremely low temperatures (well below 1K), as well as the ranges used in common refrigerators, depending on the design of the system.  Other Methods Other methods of refrigeration include the air cycle machine used in aircraft; the vortex tube used for spot cooling, when compressed air is available; and thermo acoustic refrigeration using sound waves in a pressurised gas to drive heat transfer and heat exchange.
  6. 6. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 6 1.4 UNITS OF REFRIGERATION Domestic and commercial refrigerators may be rated in kj/s, or Btu/h of cooling. Commercial refrigerators in the US are in tons of refrigeration, but elsewhere in kw. One ton of refrigeration capacity can freeze one short ton of water at 0 ºC (32 ºF) in 24 hours. Latent heat of ice (i.e. heat of fusion) = 333.55 kj/kg ≈ 144 Btu/lb One short ton = 2000lb Heat extracted = (2000)*(144)/24 hr = 288000 Btu/24 hr = 12000 Btu/hr = 200 Btu/min 1 tonne of refrigeration = 200 Btu/min = 3.517 kj/s = 3.517 kwThe practical unit of refrigeration is expressed in terms of ‘tonne of refrigeration’ (briefly written as TR). A tonne of refrigeration is defined as the amount of refrigeration effect produced by the uniform melting of one tonne (1000 kg) of ice from and 0 ºC in 24 hours. Since the latent heat of ice is 335 kj/kg, therefore one tonne of refrigeration, 1 TR = 1000 * 335 kj in 24 hours = (1000) * (335) / (24) * (60) = 232.6 kj/min In actual practice, one tonne of refrigeration is taken as equivalent to 210 kj/min or 3.5 kw (i.e. 3.5 kj/s). 1.5 COEFFICIENT OF PERFORMANCE OF A REFRIGERATOR The coefficient of performance (briefly written as C.O.P.) is the ratio of heat extracted in the refrigerator to the work done on the refrigerant. It is also known as theoretical coefficient of performance. Mathematically, Theoretically C.O.P. = Q/W Where Q = Amount of heat extracted in the refrigerator ( or the amount of refrigeration effect produced, or the capacity of a refrigerator), and W = Amount of work done.
  7. 7. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 7 1.6 APPLICATIONS  Food processing, preservation and distribution  Storage of Raw Fruits and Vegetables  Fish  poultry  Dairy Products o Ice cream o Butter o Cheese o Buttermilk o Beverages o Candy o Processing and distribution of frozen food  Chemical and process industries  Separating of gases  Condensation of gases  Dehumidification of Air  Storage as liquid at low pressure  Cooling for preservation  Special application of refrigeration  Cold Treatment of Metals  Medical  Ice Skating Rinks  Construction  Desalination of water  Ice manufacturer  It is also widely used for the cooling of storage chambers in which perishable food, drinks and medicines are stored.  The refrigeration also has wide applications in sub-marine ships, rockets and aircrafts.
  8. 8. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 8 CHAPTER 2 REFRIGERATION PROCESS 2.1 REFRIGERATOR Refrigerator keeps things cold because of the nature of the heat. Thermodynamics essentially starts that if a cold object is placed to a next to a hot object, the cold object will become warmer and the hot object will become cooler. A refrigerator does not cool items by lowering their original temperature; instead, an evaporating gas called a refrigerant draws heat away, leaving the surrounding area much colder. Refrigerators and air conditioners both work on the principle of cooling through evaporation. A refrigerator consists of two storage compartment – one for frozen items and the other for items through the entire system is pure ammonia, which evaporates at -27 ºF. this system is closed, which means nothing is lost or added while it is operating. Because liquid ammonia is a powerful chemical, a leaking refrigerator should be repaired or replaced immediately. The refrigeration process begins requiring refrigeration but no freezing. These compartments are surrounded by a series of heat-exchanging pipes. Near the bottom of the refrigerator unit is a heavy metal device called a compressor. The compressor is powered by an electric motor. More heat-exchanging pipes are coiled behind the refrigerator. Running with the compressor. Ammonia compressed until it becomes very hot from the increased pressure. This heated gas flows through the coils behind the refrigerator, which allows excess heat to be released into the surrounding air. This is why users sometimes fill warm air circulating around the fridge. Eventually the ammonia cools down to the point where it becomes a liquid. This liquid form of ammonia is then forced through a device called an expansion valve or capillary tube. Essentially, the expansion valve has a small opening or the capillary tube has a very small diameter of copper tube that the liquid ammonia is turned into a very cold, fast-moving mist, evaporating as it travels through the coils in the freezer. As the evaporating ammonia gas absorbs more heat, its temperature rises. Coils surroundings the lower refrigerator compartment are not as compact. The cool ammonia still draws heat from the warmer objects in the fridge, but not as much as the freezer section. The ammonia gas is drawn
  9. 9. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 9 back into the compressor, where the entire cycle of pressurization, cooling and evaporation begins anew. 2.2 REFRIGERATION CYCLE The refrigeration cycle uses a fluid, a called a refrigerant, to move heat from one place to other. We will begin with the cool, liquid refrigerant entering the indoor coil, operating as the evaporating during cooling. As the name implies, refrigerant in the evaporator “evaporator”. Upon entering the evaporator, the liquid refrigerant’s temperature is between 40 and 50 ºF and without changing its temperature, it absorbs heat as it changes state from a liquid to a vapour. The heat comes from the warm, moist room air blown across the evaporator coil. As it passes over the cool coil, it gives up some of its heat and moisture may condense from it. The cooler, drier room air is re-circulated by a blower into the space to be cooled. The vapour refrigerant now moves into the compressor, which is basically a pump that raises the pressure so it will move through the system. The increased pressure from the compressor causes the temperature of the refrigerant to rise. As it leaves the compressor, the refrigerant is a hot vapour, roughly 120 to 140 º F. It now flows into the refrigerant-to-water heat exchanger, operating as the condenser during the cooling. As it condenses, it gives up heat to the loop, which is circulated by a pumpas the refrigerant leaves the condenser, it is cooler, but still under pressure provided by the compressor. It then reaches the expansion valve or capillary tube. That the high pressure refrigerant to “flash” through becoming a lower pressure, cooled liquid. When pressure is reduced, as with spraying an aerosol can or a fire extinguisher, it cools. The cycle is complete as the cool, liquid refrigerant re-enters evaporator to pick up room heat. 2.3 HOW REFRIGERATOR WORKS In the summertime, have you ever gotten out of a swimming pool and then felt very cold standing in the sun? That’s because the water on your skin is evaporating. The air carries off the water vapour, and with it being taken away from your skin. This is similar to what happens inside older refrigerators. Instead of eater, through, the refrigerator uses chemicals to do the cooling. There are two things that need to be known
  10. 10. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 10 for refrigeration. 1. 2. A gas cools on expansion. When you have two things that are difference temperature that touch or are near each other, the hotter surface cools and the colder surface warms up. This is a law of physics called the Second Law of Thermodynamics. 2.4 TYPES OF DOMESTIC REFRIGERATOR There are two types of domestic refrigerator. 1. Single door fresh food refrigerator 2. Double-door refrigerator-freezer Most domestic refrigerator are of two types – either a single door fresh food refrigerator or a two-door refrigerator-freezer combination, with the freezer compartment on the top portion of the cabinet, or a vertically split cabinet (side-byside), with the freezer compartment on the left side of the cabinet. They are completely self-contained units and are easy to install. Most refrigerators use R-22 refrigerant, normally maintaining temperatures of 0 ºF in the freezer compartment and about 35 ºF to 45 ºF in the refrigerator compartment. Fig. 2.4(a) Single door Fig. 2.4(b) Double door
  11. 11. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 11 2.5 TEMPERATURTE ZONE AND RATING Some refrigerators are now divided into four zones to store different types of food: » » » » -18 ºC (0 ºF) (freezer) 0 ºC (32 ºF) (meats) 5 ºC (49 ºF) (refrigerator) 10 ºC (50 ºF) (vegetables) The capacity of a refrigerator is measured in either litres or cubic feet (US). Typically the volume of a combined fridge-freezer is split to 100 litres (3.53 cubic feet) for the freezer and 140 litres (4.94 cubic feet) for the refrigerator, although these values are highly variable. Temperature settings for refrigerator and freezer compartments are often given arbitrary numbers (for example, 1 through 9, warmest to coldest) by manufacturers, but generally 2 to 8 ºC (36 to 46 ºF) is idle for the refrigerator compartment and -18 ºC (0 ºF) for the freezer. Some refrigerators require a certain external temperature 16 ºC (60 ºF) to run properly. Thus can be an issue when placing a refrigerator in an unfinished area such as a garage. 2.6 REFRIGERANT Refrigeration application Short description Typical HFCs usedDomestic Refrigeration Commercial Appliances used for keeping food in dwelling units. Holding and displaying frozen and fresh HFC-134a R 404A, R 507, Refrigeration food in retail outlets HFC-234a Food processing and cold Equipment to preserve, process and store R410A, storage food from its source to the wholesale and cooling Industrial Refrigeration Large equipment, typically 25 kW to 30 MW, used for chemical processing, cold storage, food processing and district Transport refrigeration heating and cooling Equipment to preserve and store goods, primarily foodstuffs, during transport by road, rail, air and sea R410A, R407C, HFC-134A R407C,R 507, HFC-134a HFC-134a, R404A, R-507.
  12. 12. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 12 2.7 VAPOUR COMPRESSION CYCLE 2.7.1 Introduction The vapour compression cycle is the mostly widely used method of refrigeration in the modern application. Your household refrigerator, water cooler, deep freezer, air conditioneretc. all run on vapour compression cycle. The cycle is called as vapour compression cycle, because the vapours of refrigerant are compressed in the compressor of the system to develop the cooling effect. 2.7.2 Working Here are the various process of vapour compression cycle . (1) Compression: The vapours of refrigerants enter the compressor and get compressed to high pressure and high temperature. During this process the entropy of the refrigerant ideally remains constant and it leaves in superheated state. (2) Condensation: The superheated refrigerant then enters the condenser where it is cooled either by air or water due to which its temperature reduces, but pressure remains constant and it gets converted into liquid state. (3) Expansion: The liquid refrigerant then enters the expansion valve or throttling valve or capillary tube when sudden expansion of the refrigerant occurs, due to which its temperature and pressure falls down. The refrigerant leaves expansion valve or capillary tube in partially liquid state and partially in gaseous state. (4) Evaporation or cooling: The partially liquid and partially gaseous refrigerant at very low temperature enters the evaporator where the substance to be cooled is kept. It is here where the refrigeration effect is produced. The refrigerants absorbs the heat from tge substance to be cooled and gets converted into vapour state. Fig 2.7 : Simple VCR System T-S diagram of VCR SystemFig 2.8 : P-V diagram of VCR System.
  13. 13. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 13 2.7.3 Advantages  Capable of large refrigerating loads at lower initial purchase and operating cost.  Very efficient  Very compact system for small to very large heat loads.  Cycle can be reversed for heat pump operation. 2.7.4 Disadvantages  Parts can wear out.  Noise.  Potential refrigerant leaks.  Operates in limited orientation. 2.7.5 Application  Household refrigerator,  Air-conditioners,  Water coolers,  Ice and Ice cream maker,  Deep freezers,  Large industrial refrigeration and  Air-conditioning systems,
  14. 14. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 14 2.8 VAPOUR ABSORPTION CYCLE 2.8.1 Introduction The various processes of the vapour absorption cycle are similar to the one in vapour compression cycle, only the method of compression of the refrigerant is different. In vapour absorption system ammonia is used as the refrigerant, which has very high affinity to dissolve in water. Here are various processes of vapour absorption cycle; 2.8.2 Working (1) Compression or absorption of the refrigerant: in vapour absorption system there is no traditional compressor, instead there is absorber. The absorber consists of water, as a absorbent, in which the refrigerant, ammonia, dissolves. This mixture of water and ammonia is then pumped and heated thus increase in temperature and pressure of the ammonia occurs. Ammonia leaves the absorber at high pressure and high temperature. Some work has to be provided to the pump and heating is carried out by the steam. The amount of electricity required by the pump is much lesser than that required by the compressor hence there is lots of saving of electricity, however, the additional source of heat in the form of steam has to be provided. (2) Condensation: The refrigerant at pressure and temperature then enters condenser where it is cooled by water and its temperature and pressure reduces. (3) Expansion: Thereafter the expansion of refrigerant occurs in throttling valve or capillary tube due to which the temperature and pressure of the ammonia refrigerant reduces drastically and suddenly. (4) Evaporation: Finally the refrigerant enters the evaporator where it produces the cooling effect. It leaves the evaporator in vapour state and then enters absorber, where it is absorbed by absorbent, water and compressed by the pump. This process repeats again and cycle continues. There are different types absorbents like water and lithium bromide
  15. 15. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 15 that can be used with refrigerant ammonia. These systems are called water absorption system. 2.8.3 Advantages  No moving parts.  No vibration or noise on small system.  Small systems can operate without electricity using only heat, large systems require power for chemical pumps.  Can make use of waste heat. 2.8.4 Disadvantages  Potential refrigerant leaks.  Operates under limited vibration and orientations.  Complicated and difficult to service and repair.  Stalls in a hot ambient  Very bulky.  Poor efficiency.
  16. 16. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 16 CHAPTER 3 LPG REFRIGERATION 3.1 Introduction Although government agencies are not able to continuously supply a major portion of electricity in both the urban as well as in rural areas. Still the people in these regions require refrigeration for a variety of socially relevant purposes such as cold storage or storing medical supplies and domestic kitchens this project has the novelty of using LPG instead of electricity for refrigeration. This solution is convenient for refrigeration in regions having scares in electricity. It works on the principle that during the conversion of LPG into gaseous form, expansion ofLPG takes place. Due to this expansion there is a pressure drop and increase in volume of LPG that results in the drop of temperature and a refrigerating effect is produced. This refrigerating effect can be used for cooling purposes. So this work provides refrigeration for socially relevant needs as well as replaces global warming creator refrigerants. While going through the literature review in LPG refrigeration system, Conventional VCR (Vapour Compression Refrigeration System) uses LPG as refrigerant and produced the refrigerating effect. But in our proposed very simple type of refrigeration system in which the high pressure LPG is passing through a capillary tube and expands. After expansion the phase of LPG is changed and converted from liquid to gas and then it passes through the evaporator where it absorbs the heat and produces the refrigerating effect. After evaporator it passes through the gas burner where it burns. LPG consists mainly of propane (R-290) and butane (R-600), and LPG is available as a side product in local refineries. In Cuba for already several decades LPG is used as a drop-in refrigerant. LPG mixtures have composition of a commercial LPG mixture suitable as „drop-in‟ replacement for R-12 was calculated crudely as 64% propane and 36% butane by mass. Liquefied petroleum gas (LPG) of 60% propane and 40% commercial butane has been tested as a drop-in suitable for R 134a in a single evaporator domestic refrigerator with a total volume of 10 ft3. In March 1989, the Institute of Hygiene in Dortmund Germany needed a new cold storage room. The young
  17. 17. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 17 idealistic director, Dr Harry Rosin, could not consider using a CFC refrigerant and so tried propane and iso butane. Greenpeace Australia imported a Foron refrigerator in February 1993 and in December 1993 Email Ltd, Australia’s largest appliance manufacturer,displayed prototype LPG refrigerators. 3.2 PROPERTIES OF LPG  Colourless  Odourless-(It’s normal to odorize LPG by adding an odorant prior to supply to the user, to aid the detection of any leaks).  Flammable.  Heavier than air  Approximately half the weight of water.  Nontoxic but can cause asphyxiation.  A good mixture: LPG is mainly Propane (C3H8),Butane (C 4H10) or a mixture of Propane/Butane.  Since LPG has a simple chemical structure, it is among the cleanest of any alternative fuel.  Boiling Point: LPG’s boiling point ranges from -42 0C to 0 0C depending on its mixture percentage of Butane and Propane.  Combustion: The combustion of LPG produces (CO2) and water vapour but sufficient air must be available. Inadequate appliances fluing or ventilation can result in the production of carbon monoxide which can be toxic.  Vapour Pressure: LPG is stored as liquid under pressure. It iscolourless and its weight is approximately half that of an equivalent volume of water. The pressure inside a closed container in which LPG is stored is equal to the vapour pressure of the liquid and corresponds to its temperature.  Ignition Temperature: The temperature required to ignite LPG in air is around 5000C.  Calorific Value: The calorific value of LPG is about 2.5 times higher than that of main gas so more heat is produced from the same volume of gas.
  18. 18. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 18  Toxicity:LPG is colourless, odourless and non -toxic gas. It is supplied commercially with an added odorant to assist detection by smell.  LPG is excellent solvent of petroleum and rubber product and isgenerally non – corrosive to steel and copper alloys. 3.3 APPLICATIONS Application of LPG as refrigerant that divides in two categories:  Processes that uses LPG  Industries that uses LPG  Processes that use LPG LPG’s high calorific value makes it a key gas for:  Heating appliances: - used because of its case of combustion, portability and clean burning characteristics and compatibility with almost all water and space heating appliances. The best product depends the climate.  Propane: - suitable for use in all conditions. It is the only LPG product suitable for cold climates (such as the UK and Canada) because of its low boiling point of -43.6 ºF (- 42 ºC).  Butane: - suitable for use in hot climate only because of its higher boiling point of 22.9 ºF (-5 ºC).  Propane/Butane mixtures: - suitable for use in moderate climates. Cooking: - preferred to electricity by professional chefs.  Oxy-Fuel application: - LPG performs well in large-scale oxy-fuel burner application. LPG’s clean burning characteristics make it a good gas for:  Transport fuel: - for forklift and other trucks that operate inside warehouses and factories because it provides no noxious exhaust gases and give more power than batteries. LPG is also increasingly used as a clean automotive fuel in countries with serious air pollution problems.  Propane and butane’s low boiling points also give them good closed cycle refrigerants characteristics (similar to Freon’s).  Industries that use LPG LPG’s calorific and clean-burning characteristics are used across many industries such as:
  19. 19. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 19  Automotive: - as a forklift truck fuel and in some countries as a private car or public transport fuel.  Hospitality and Leisure: - as a heating and cooking gas in restaurant, cafes and mobile catering vans.  Agriculture: - for crop drying, heating g reenhouses and animal sheds and for flame weeding and pest control.  Construction :- LPG’s portability allow its use for general space heating to enable work on projects during winter months, and for road heating in bitumen replacement work.  Chemicals and petrochemicals: - LPG surplus is used as feedstock when prices are low. 3.4 The LPG Refrigeration Cycle LPG Gas Cylinder: From the LPG gas cylinder of 14.5 kg, LPG flows through the pipe and reaches to the capillary tube.LPG gas pressure is approximate 12.41 bars Capillary Tube: As the capillary tube, capillary tube downs thepressure up to less than 1.2 bars. Evaporator: In the evaporator LPG is converted into the vapor from with low pressure. After passing through theevaporator low pressure and temperature LPG vapor absorbs heat from the chamber system. Gas Burner: After performing the cooling effect, low pressure LPG gas goes into the burner where the burns. As weknow whenever the fluid flow through the narrow pipe there is a
  20. 20. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 20 pressure drop. The amount of pressuredrop in our system is calculated. [10] From the Darcey-Weisbach equation, thepressure drop in the refrigerant piping is calculated for 13 feet length tube is 0.23 in terms of equivalent length. 3.5 PARTS OF REFRIGERATORS 3.5.1 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 application of a liquefied at a normal temperature by moderate pressure increases or at normal pressure by application of LPG using refrigeration. LPG is used as a fuel for domestic, drying can industrial, LPG be horticultural, to agricultural, another cooking, heating fuel or as LPG processes. Also can be used as automotive specialist propellant foraerosal . Fig 3.5.1 LPG Gas Cylinder
  21. 21. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 21 3.5.2 Capillary Tube The capillary tube is the commonly used throttling device in the domestic refrigeration. The capillary of very would occupy used for the the tube is a copper tube of very less space. The small internal of diameter. It is long length and it is coiled to refrigeration several turns so that it the capillary tube to 2.28 mm When picture. internal diameter tube applications varies from 0.5 is shown in (0.020 to 0.09 inch). The capillary refrigerant enters in the capillary tube, its pressure drops down suddenly due to very small diameter. The decrease in pressure of the refrigerant through the capillary depends on the diameter of capillary and the length of capillary. Smaller is the diameter and more is the length of capillary more is the drop in pressure of the refrigerant as it passes through it. Fig 3.5.2 Capillary Tube 3.5.3 Evaporator The evaporators are another important parts of the refrigeration systems. It through the evaporators that the cooling effect is produced in the refrigeration system. It is in the evaporators when the actual cooling effect takes place in the refrigeration systems. For many people the evaporator is the main part of the refrigeration system, consider other part as less useful. The evaporators are heat exchanger surface that transfer the heat from the substance to be cooled to the refrigerant, evaporators’ refrigeration thus removing the heat from the are used for wide variety in and hence the available from of the substance. The diverse application in wide variety of shape, sizes and they are also
  22. 22. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 22 classified in different manner depending on the method of feeding the refrigerant, construction of the evaporator, direction of air circulation around the evaporator, application and also the Fig 3.5.3 Evaporator refrigerant control. In the domestic refrigerators the evaporators are commonly known as freezers since the ice is made in these compartments. In the evaporators the refrigerant enters at very low pressure and temperature after passing through the capillary tube. This refrigerant absorbs the heat from the substance that is to be cooled so the refrigerant gets heated while the substance gets cooled. Even after cooling the substance the temperature of the refrigerant leaving the evaporator is less than the substance. In the large refrigeration plants the evaporator is used for chilling water. In such cases shell and tube type of heat exchanger are used as the evaporators. In such plants the evaporators are classified as: (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
  23. 23. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 23 (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, (3). Defrosting evaporator 3.5.4 Pressure gauges Many techniques have been developed for the measurement of pressure and vacuums. Instruments used to measure pressure are called pressure gauges or vacuum gauges. A manometer could also referring to a pressure measuring instrument, usually limited to measuring pressures near to atmospheric. The term manometer column hydrostatic instruments. is often used to refer specifically to liquid Stainless steel pressure gauge Catering to the requirements of to power and allied array of stainless Industry, we offer quality steel, weatherproof pressure gauges. Renowned for offering control equipment, chemicals and petrochemicals and resistance in corrosive environments and modes, these find wide application in power generation, pollution also exploration.
  24. 24. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 24 These gauges are available in 63mm, 100mm, and 150mm sizes and can be customized as per client. Bourdon gauge A Bourdon gauge uses a coiled tube, which, as it expands due to pressure increases cases a rotation of an arm connected to the tube. Fig 3.5.4 Pressure Gauges 3.5.5 High Pressure pipes The range of high pressure pipes covers most steel ball fitted these to both application where there is a nipples press thus sealing requirement to transfer gas at high pressure. They consist of a steel pipe with an ends. Two swiveling connection balls against the seating of the connectinghole and against gas leakage.» » Wide range of pipes. All pipes are pressure tested to 100 M Pa (14,500 psi) over recommended working pressure.
  25. 25. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 25 3.6 Basic Experimental Setup of LPG refrigeration system The basic components in this system are shown in set up diagram and the changes in thermodynamicsproperties of the fluid flowing (LPG) is shown in the systems line diagram. Fig 3.6 Experimental Setup of Basic LPG Refrigeration System
  26. 26. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 26 3.7 Design of LPG Refrigeration System There are main four parts in this system 1. Copper Tubes (For carrying LPG cylinder to filter before capillary) 2. Capillary tube 3. Valves (Gas supply control valves) 4. Evaporator 3.7.1 Copper Tubes Air-Conditioning and Refrigeration Systems—Copper is the preferred material for use with most refrigerants. Because of its good heat transfer capacity as well as corrosion resistance and cheaperin cost. As for all materials, the allowable internal pressure for any copper tube in service is based onthe formula used in the American Society of Mechanical Engineers Code for Pressure Piping (ASME B31) P = 2S (tmin – C)/ Dmax – 0.8 (tmin – C) Where: P = allowable pressure, bar S = maximum allowable stress in tension, bar tmin = wall thickness (min.), in mm Dmax = outside diameter (max.), in mm C = a constant for copper tube, because of copper’s superior corrosion resistance, the B31 code permitsthe factor C to be zero. Thus the formula becomes: P = 2Stmin /Dma – 0.8tmin According to the pressure 100 psi the tube outside diameter is become = 7 mm and the thickness of thetube is = 1.5 mm. 3.7.2 Capillary tube An analytical computation of length of capillary tube The fundamental equations applicable to the controlvolume bounded by points 1and 2 in fig. are
  27. 27. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 27 1. Conservation of mass 2. Conservation of energy 3. Conservation of momentum The equation relating state and conditions at points 1and 2 in a very short length of capillary tube in thefigure is written using following notions [4]. A: Cross sectional area of inside of tube, m² D: ID of tube, m. f: friction factor, dimensionless h: enthalpy, kJ/kg. hf : enthalpy of saturated liquid , kJ/kg hg : enthalpy of saturated vapour, kJ/kg ΔL: length of increment, m. P: pressure, Pa Re: Reynolds No., VD/Ʋ v: specific volume of m³/kg vf : specific volume of saturated liquid, m³/kg vg: specific volume of saturated vapour, m³/kg V: velocity of refrigerant, m/s w: mass flow rate, kg/s x: dryness friction μ: Viscosity, pa×s μf: viscosity of liquid, pa×S μ g: viscosity of Vapour, pa×s For calculation of length of capillary tube we haveused the following relations and find out the length. The equation of conservation of mass is as follows w =V1A/ v1 = V2A/ v2... (1) or
  28. 28. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 28 w=V1/ v1 = V2/ v2 ... (2) The conservation of energy gives 1000 h1+ V²1/ 2 =1000 h2+V²2/ 2... (3) This assumes negligible heat transfer in and out of system. The momentum equation in words states thatthe difference in forces applied to the elementbecause of drag and pressure difference on opposite ends of the element equals that is needed to accelerate the fluid [6]. [(p1-p2) - fΔ L/D V2/ 2v] A = w (V1-V2)..... (4) As the refrigerant flows through the tube, its pressure and saturation temperature progressively drop and thefraction of vapour .x. continuously increases. At any point h = hf (1-x) + x hg.... (5) v = vf (1-x) + x vg..... (6) The quantities of equation (4) V, v and f all change as refrigerant flows from point 1 to 2. Simplifying usingequation (2) f ΔL/D. V2/ 2v = f ΔL/D V/ 2 w/A...... (7) In the calculation to follow, V used in equation (7)will be mean velocity Vm = V1+ V2 / 2..... (8) The friction factor with turbulence is F= 0.33/Re 0.25 = 0.33/ (VD/ μ v) 0.25... (9) The viscosity in two phase flow is given by μ = μf (1-x) + x μg.... (10) The mean friction factor fm applicable to incrementallength 1-2 is fm = f1+f2/2 = [0.33/Re1 0.25 + 0.33/Re2 0.25]/ 2... (11) The essence of the analytical calculation is to determine the length ΔL between points 1-2 as shownin fig. for a given reduction in saturation temperature of the refrigerant. The flow rate and other conditionsat point 1 are known and for a required selected temperature at point 2, The Remaining conditions atpoint 2 and ΔL would be computed in the following steps: 1. Temperature t2 selected
  29. 29. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 29 2. p2, hf2, hg2, vf2, and vg2 are computed, all beingfunction of temperature (or pressure). 3. Combination of equation (2) and (3) gives 1000 h 2+ v²2/ 2 (w/A)2 =1000 h1+ v²/ 2... (12) Substituting equations (5) and (6) into (12) 1000 hf2 +1000(hg2- hf2) x + [{vf2+ (vg2 - vf2) x} ²(w/A) ²] = 1000 h1 + V1 2/ 2...... (13) In equation, all quantities being knows except x,which could be solved by quadratic equation, X= [-b+√b2-4ac]/2a.... (14) Where, a = (vg2- vf2)2 (w/A) 2×1/2 b= 1000(hg2- hf2) + vf2 (vg2 - vf2) (w/A) and c = 1000(hf2- h1) + (w/A) 2 1/2 vf2 2- V1 2/2 Properties of LPG at 10.27 bars [16] hf1 = enthalpy of saturated liquid = 169.1kJ/kg hg1 = enthalpy of saturated vapour = 498.0kJ/kg vf1 = specific volume of saturated liquid = 2.050×10-3m³/kg vg1= specific volume of saturated vapour = 0.0448m³/kg Properties of LPG at 1.67 bars hf2 = enthalpy of saturated liquid = 22.9kJ/kg hg2 = enthalpy of saturated vapour = 435.0kJ/kg vf2 = specific volume of saturated liquid = 1.763×10-3m³/kg vg= specific volume of saturated vapour = 0.2585m³/kg w = V/v V= volume flow rate = 1.1liter/ hr w =9.45×10-4 Kg/sec From this calculation the length of capillary tube is= 2.97m
  30. 30. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 30 3.7.3 Valves In this system we have used two flow control valves of globe type of 4 mm of internal diameter. 3.7.4 Evaporator Evaporators are heat exchangers with fairly uniform wall temperature employed in a wide range ofHVAC-R products, spanning from household to industrial applications. In general, they are designedaiming at accomplishing a heat transfer duty at the penalty of pumping power. There are two well establishedmethods available for the thermal heat exchanger design, the log-mean temperature difference (LMTD) and the effectiveness/number of transfer units (e-Ntu) approach (Kakaç and Liu, 2002; Shah and Sekulic, 2003). The second has been preferred to the former as the effectiveness, defined as the ratio between the actual heat transfer rate andthe maximum amount that can be transferred, provides a 1st-law criterion to rank the heat exchanger performance, whereas the number of transfer units compares the thermal size of the heat exchanger with its capacity of heating or cooling material. Furthermore, the e-Ntu approach avoids the cumbersome iterative solution required by the LMTDfor outlet temperature calculations. [14] In general, evaporators for refrigeration applicationsare designed considering the coil flooded with twophase refrigerant, and also a wall temperature close tothe refrigerant temperature (Barbosa and Hermes, 2012), so that the temperatureprofilesalong thestreams are not constant, in these cases, the heat transfer rate if it is calculated from: [13] Q = m.cp (To – Ti) = ɛ.m.cp (Ts − Ti) Where m is the mass flow rate, Ti, To and Ts are the inlet, outlet and surface temperatures, respectively, Q=h × As (Ts-Tm) is the heat transfer rate, Tm is themean flow temperature over the heat transfer area,As, and ɛ is the heat exchanger effectiveness,calculated from (Kays and London, 1984): e = 1 – exp (−NTU)
  31. 31. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 31 Where NTU is the number of transfer units. We have selected the plate and tube type evaporator because itprovides a gentle type of evaporation with low residence time. It also preserves the food and otherproducts from bacterial attack. It requires low installation cost.
  32. 32. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 32 3.8 Design calculations for evaporator The evaporator has following dimensions: Length = 325 mm, Breadth = 265 mm and Height = 135 mm The evaporator is made from six plywood sheets of 3mm thickness which enclose six thermocol sheets of10mm thickness. The areas for these sheets are as follows: Area1 = 265×135 = 0.03578 m2, Area2 = 265×325 = 0.08612m2, Area3 = 265×135 = 0.03578m2, Area4 = 265×325 = 0.08612m2, Area5 = 325×135 = 0.04388 m2, Area6 = 325×135 = 0.04388 m2, Thermal conductivity of plywood kp = 0.12 W/m.k Thermal conductivity of thermo coal kt = 0.02 W/m.k Thickness of plywood = 3 mm Thickness of thermo coal = 10 mm Temperature of atmosphere = 35 0C = 298 K Temperature of evaporator = 16 0C = 289 K Heat flow from area 1 due to conduction Q1 = (Ta-Te)/ (Rthp + Rtht) = (Ta-Te)/ ((Lp/KP.A) + (Lt/Kt.A)) = (294-289)/ (0.698+13.97) = 2.317W Heat flow from area 2 due to conduction Q2 = 5.58 W, Q3 = 2.32 W, Q4 = 5.58 W, Q5 = 2.84 W Q6 = 2.84 W Total heat flow from all areas due to conduction = 21.47 W
  33. 33. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 33 Heat flow from evaporator due to convection Inside heat transfer coefficient = 30 W/m2.K Outside heat transfer coefficient = 10 W/m2.K Rate of heat transfer Q [12] Q =U.A. (Ta-Te) The overall heat transfer coefficient 1/U = (1/Uo) + (Lp/kp) + (Lt/kt) + (1/Ui) 1/U = 0.649 U = 1.54 W/m2.K Rate of heat transfer from area 1 Q1 = 1.54×0.03578(298-264)= 1.873W Q2 = 4.50 W, Q3 = 1.873 W, Q4 = 4.50 W, Q5 = 2.29W Q6 = 2.29 W Total heat flow from all areas due to convection =17.326 W Heat transfer due to radiation Q Q = σT4 = 5.67× 10-8(35-(16)) 4 = 0.21W Total heat flow from evaporator due to conduction, convection and radiation Qt = 21.47+17.326+0.21 =39.006W
  34. 34. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 34 The experiment of this project was done on 8 May, 2015 at 11:00 a.m. and readings were taken at 10 minute's interval, for 1 hour which is as shown in table 1 below: Table 3.8.1: Experimental Readings Sr No Inlet Pressure (Bar) Outlet Pressure (Bar) Time (min) Capillary Temp 0C Evaporator Temp 0C Water Temp 0C 1 5.745 3.009 10 32 32 32 2 5.745 2.941 20 28 30 31 3 5.745 2.804 30 26 26 29 4 5.745 2.530 40 25 21 29 5 5.745 2.530 50 24 18 27 6 5.745 2.462 60 22 16 26 Again we were taken reading on this project on same day on at 3:30 p.m. and readings were taken at 10 minute's interval, with same cylinder for 1 hour which is as shown in table 2 below: Table 3.8.2: Experimental Readings Sr No Inlet Pressure (Bar) Outlet Pressure (Bar) Time (min) Capillary Temp 0C Evaporator Temp 0C Water Temp 0C 1 5.608 2.941 10 30 31 32 2 5.608 2.872 20 28 29 31 3 5.608 2.736 30 27 26 29 4 5.608 2.599 40 25 23 28 5 5.608 2.462 50 24 19 27 6 5.608 2.394 60 22 17 27
  35. 35. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 35 Chart.1:Water Temperature v/s Time (min) Chart.2:Evaporator Temperaturevs Time(min) 0 5 10 15 20 25 30 35 10 20 30 40 50 60 Water Temperature Water Temperature 0 5 10 15 20 25 30 35 10 20 30 40 50 60 Evaporator temperature Evaporator temperature
  36. 36. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 36 Fig. p-h diagram of LPG Refrigerator Size of refrigerator: - 335×265×135 mm³ Initial temperature of water: - 30⁰C Initial temperature of evaporator: - 33⁰C Specific heat of LPG vapor is 1.495kJ/KgK
  37. 37. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 37 Refrigerating effect The properties of LPG at 5.516 bars are Enthalpy h1 = 430.3 kJ/Kg Temp. t1= 4 ⁰C The properties of LPG at 1.316 bars are Enthalpy h3 = 107.3 kJ/Kg Temp. t3= -30 ⁰C Heat extracted from evaporator in 1 hour (Qeva) = Heat gained by LPG (QLPG) (Qeva) = Heat extracted from (water + surrounding air inside of evaporator +container + leakage) mw = mass of water =6.5kg cpw = specific heat of water=4180J/kg.K (ΔT)W =28.3 0C mc =mass of container =1.30kg cpc= specific heat of aluminium container = 903J/kg.K (ΔT)c =28.3 0C xLPG = Dryness fraction of LPG from graph =0.5 (Qeva) = Qevap + Qair +Qcont +QL = mwcpw(ΔT) + macpa(ΔT) + mccpc(ΔT) +QL We have taken 6.5 kg of water in an aluminiumcontainer of weight 1.30 kg. Since there is very less amount of air so it is neglected. = 6.5×4180×28.7 + 0 + 1.3007×903×28.7 = 0.81348 MJ Heat gained by LPG (QLPG) = Latent heat gain(QL)LPG +Sensible heat gain(QSen)LPG = mLPG .xLPG .hfg + mLPG .cpLPG. (Tsup-Tsat) =9.45×10-4×0.5×375×103×3600+9.45×10-4×1.67× (- 9.3-30) = 861151.662J/hr = 0.862MJ/hr So the refrigerating effect is = h3-h2 = 630.3-307.3 = 323kJ/Kg
  38. 38. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 38 For work input we have a LPG cylinder of 14.5 Kg. so the work input is amount of energy required for filling of 1 cylinder. A typical LPG bottling plant has the following major energy consuming [8]. Equipment:- 1. LPG pumps 2. LPG compressors 3. Conveyors 4. Blowers 5. Cold repair facilities including painting 6. Air compressors and air drying units. 7. Transformer, MCC & DG sets 8. Firefighting facilities 9. Loading and unloading facilities Some of the LPG bottling plants use a comprehensive monitoring technique for Keeping track of energy / fuel Consumption on per ton basis. PCRA Energy Audit [8] 1. Consumption = 40×4200=168000kWh 2. For lighting energy consumption= 227340kWh 3. LPG compressor consumption= 153360 kWh 1. Total consumption for LPG pumps One pump having 40 kW motor and 96 m head or 150cubic meter /hour discharge Annual operating = 4200 hrs Annual energy 6 hrs /day in 350 days = 168000+227340+153360 = 548700kWh Per day consumption = 548700/350 =1567.71 kWh 500 cylinders are refilled every day, so per cylinder electricity consumption. =1567.71/500 =3.1354kWh
  39. 39. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 39 For filling of 1 LPG cylinder of 14.5 kg the power input is = 3.1354kWh So 1 kg of LPG is = 3.1354/14.5 =0.2162 kWh We run the set up for 1 hr = 0.2162×1000/ (9.45/10000) ×3600 = 63.55W COP OF THE LPG REFRIGERATION SYSTEM COP = (h3-h2)/w = (630.3-307.3)/63.55 = 5.08 After finding out the COP of the LPG refrigerator we found out the heat librated by LPG after burning in the burner with the burner efficiency of 92 %. Heat liberated by LPG QL= m×cv We have the volume flow rate of LPG is 0.1 liter per minand the specific volume of LPG at 1.56 bar pressure is 1.763×10-3 m3/Kg. So mass flow rate of LPG is = 0.0001/1.763×10-3= 0.0567 Kg/min m = 9.45×10-4 Kg/sec cv = 46.1 MJ/Kg QL= 9.45×10-4× 46.1×103 = 43.56 W
  40. 40. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 40 3.9 CostEstimation of LPG Refrigeration TOTAL COST: Rs 5375/- COST SHEET NO COMPONENT COMPONENT PRICE 1 EVAPORATER BOX 500 2 GAS PIPE 175 3 CAPILLARY TUBE 150 4 ACCUMULATOR 450 5 COPPER TUBE 300 6 INSULATOR THERMOCOL 50 7 BRAZING MATERIAL 200 8 SUCTION PIPE 175 9 C U ‘T’ CONNECTOR 350 10 BRASS NUT 175 11 HAND SUT VALVE 175 12 PRESSURE GAUGE 500 13 STRAIGHT CONNECTOR 175 14 SCREW, NUT,BOLT 300 15 BRAZING GAS CYLINDER 150 16 HIGH PRESSURE VALVE 200 17 BURNER 450 18 GAS COST 900
  41. 41. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 41 3.10 Advantages  It eliminates the blocking problem.  It is efficient to save fuel.  Low Weight.  The fridge works when electricity off. It is efficient to save fuel.  No Pollution.  Running cost is zero.  Eliminates the compressor and condenser.  Noiseless 3.11 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 can not converted again liquid phase , because the problem in LPG refrigeration system. Because of the LPG is highly flammable.
  42. 42. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 42 3.11 APPILICATIONS  Food processing, preservation and distribution 1. Storage 2. Fish 3. Meat and Poultry 4. Dairy Products (a). Ice cream (b). Butter (c). Cheese (d). Butter milk 5. Beverage 6. Candy 7. Medical
  43. 43. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 43 Conclusion The aim of the LPG refrigerator was to useLPG as a refrigerant and utilising the energy of the high pressure in the cylinder for producing the refrigerating effect. We have the LPG at a pressure of 12.41 bar in Domestic 14.5 kg cylinder equipped with a high pressure regulator and this pressure has reduced up to 1.41 bar with the help of capillary tube. But if we use a low pressure regulator as is the practice in conventional domestic LPG gas stove, the pressure of LPG after the expansion device and before the burner would be different. So we have calculated the refrigerating effect with the help of changes in properties of LPG (pressure, temperature, and enthalpy) before and after the evaporator using high pressure regulator and the amount ofrefrigerating effect is 323kJ/Kg.
  44. 44. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 44 Future Scope Positive result of experimentation pushes me to go ahead with this normal product and introduce new product range in the field of refrigeration. Which focus on the restaurant and Community hall, and mid-day meal of school and college to decrease the product and cost and for preserving vegetables ,milk etc.at small lair and snacks shop by increase the portability of the refrigerator by reducing the weight and eliminating the compressor with no cost of refrigerating and light weight and light maintenance free product.  It may very useful for the desert, research and mines area and many other area of under developed country, where electricity not easily available.  It can be apply for the system as an air conditioning in LPG cars.  This system most suitable for hotel, industries, refinery, chemical industries where consumption of LPG is very high.
  45. 45. LPG REFRIGERATOR DEPARTMENT OF MECHANICAL ENGINEERING KLS VDRIT, HALIYAL Page 45 References 1. Shank K. Wang, Handbook of air conditioning and refrigeration” Edition. 2. A. Baskaran, P. Koshy Mathews, International Journal of Scientific and Research Publications”, Volume 2, Issue 9, 1 ISSN 2250- 3153, September 2012 3. B. O. Bolaji, Investigating the performance of some environment-friendly refrigerants a alternative to R12 in vapour compression refrigeration system”, PhD Thesis in the Department of Mechanical Engineering, Federal University of Technology Akure, Nigeria (2008). 4. Prashant Sharma, Rahul Sharma, “International Journal of Latest Research in and Technology” ISSN (Online):2278- 5299 Vol.1,Issue 1 :45-48,May-June(2012) 5. ASHRAE, “Thermo physical Properties of Refrigerants”, Chapter 20, ASHRAE Fundamental, Inc. Atlanta 20 (2001) 1-67. 6. W. F Stoecker., and J. W. Jones, “Refrigeration and Air conditioning”, TATA McGraw-Hill pub. Co. Ltd.pp. 264. 7. ASHRAE, 2002, “Adiabatic capillary tube selection”, Refrigeration Handbook, chapter. 45, pp.45.26-45.30, ASHRAE. 8. “PCRA energy audit report”, HPCL LPG bottling plant AsaudaBahadurgarh (Haryana) Dec. 2006. 9. “Basic statics on Indian petroleum and natural gas” 2006-07. 10. Shank K. Wang, “Handbook of air conditioning and refrigeration” page no. 11.14 chapter 11. 11. ASHRAE handbook 1998. 12. C.P. ARORA, “Hand book of Refrigeration and air conditioning”, by page no. 425 13. A. Bejan, “The thermodynamic design of heat and mass transfer processes and devices”, Heat and Fluid Flow pp.258-276, 1987 14. Hermes CJL, “Conflation of e-Ntu and EGM design methods for heat exchangers withuniform wall Temperature”, Int. J. Heat andMass Transfer, pp.3812-3817, 2012. 15. J R Barbosa, C Melo, CJL Hermes, PJ Waltrich, “A Study of the Air-Side Heat Transfer and Pressure Drop Characteristics of Tube-Fin ‘No-Frost’ Evaporators”, Applied Energy 86, pp.1484-1491, 2009.

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