Вы искали: liquefied (Английский - Индонезийский)

liquefied natural gas
gas alam cair

1. introduction in developing country like india, most of the vapour compression based refrigeration, air conditioning and heat pump systems continue to run on halogenated refrigerants due to its excellent thermodynamic and thermo-physical properties apart from the low cost. however, the halogenated refrigerants have adverse environmental impacts such as ozone depletion potential (odp) and global warming potential (gwp). hence, it is necessary to look for alternative refrigerants to full fill the objectives of the international protocols (montreal and kyoto) and to satisfy the growing worldwide demand. in earlier days, ethyl chloride was used as a refrigerant which soon gave way to ammonia as early as in 1875. at about the same time, sulphur dioxide in 1874, methyl chloride in 1878 and carbon dioxide in 1881, found application as refrigerant. during 1910-30 many new refrigerants, such as n2o3, ch4, c2h6, c2h4, c3h8 wereajeet kumar rai, amit kumar, pravin kumar and ayaj ahamad ansari http://www.iaeme.com/ijmet/index.asp 44 editor@iaeme.com employed for medium and low temperature refrigeration. hydrocarbons were, however, found extremely inflammable. dichloromethane, dichloroethylene and monobromomethane were also used as a refrigerant for centrifugal machines. a great break through occurred in the field of refrigeration with the development of freons. freons are a series of fluorinated hydrocarbons, generally known as fluorocarbons, derived from methane, ethane, etc., as bases. with fluorine, chlorine sometimes bromine in their molecules, these form a series of refrigerant with wide range of normal boiling point to satisfy the varied requirements of different refrigerating machines. the presence of fluorine in the molecule makes the compound non-toxic and imparts other desirable physical and physiological characteristics. plank has given individual treatment to some 50 inorganic and organic refrigerant. among the most common inorganic refrigerant are ammonia, water, carbon dioxide. presently, the most commonly used organic refrigerant are the chloro-fluoro derivatives of ch4 and c2h6. the fully halogenated ones with chlorine in their molecule are chlorofluorocarbons, referred to as cfcs. those containing h atoms in the molecule along with cl and f atoms are referred to as hydro-chloro-fluoro carbons or hcfcs. simple hydrocarbons are hcs, thus, we have hcs, hfcs, hcfcs and cfcs. alsaad and hammad (1998) investigates the result of an experimental study carried out to determine the performance of a domestic refrigerator when a propane/butane mixture is used as a possible replacement to the traditional refrigerant cfc 12. the used propane/butane mixture is liquefied petroleum gas (lpg) which is locally available and comprises 24.4% propane, 56.4% butane and 17.2% isobutane. the refrigerator worked efficiently when lpg was used as refrigerant instead of cfc 12. the evaporator temperature reached -15c with cop value of 3.4 at a condenser temperature of 27°c and an ambient temperature of 20°c. fatouh and kafafy (2006) made an attempt to test liquefied petroleum gas (lpg) of 60% propane and 40% commercial butane as a drop-in substitute for r134a in a single evaporator domestic refrigerator with a total volume of 10 ft3 (0.283 m3). continuous running and cycling tests were performed on that refrigerator under tropical conditions using different capillary tube lengths and various charges of r134a and lpg. continuous running and cycling results showed that r134a with a capillary tube length of 4 m and charge of 100 g or lpg with capillary tube lengths from 4.0 to 6.0 and charge of 50 g or more satisfy the required freezer air temperature of 12 c. the lowest electric energy consumption was achieved using lpg with combination of capillary tube length of 5 m and charge of 60 g. this combination achieved higher volumetric cooling capacity and lower freezer air temperature compared to r134a. the performance of the refrigerator using hydrocarbons as refrigerants was investigated and compared with the performance of refrigerator when r-134a was used as refrigerant by sattar et al (2007). the effect of condenser temperature and evaporator temperature on cop, refrigerating effect, condenser duty, work of compression and heat rejection ratio were investigated. the energy consumption of the refrigerator during experiment with hydrocarbons and r-134a was measured. the results show that the compressor consumed 3% and 2% less energy than that of hfc-134a at 28°c ambient temperature when iso-butane and butane was used as refrigerants respectively. the energy consumption and cop of hydrocarbons and their blends shows that hydrocarbon can be used as refrigerant in the domestic refrigerator. the present work has been started with the objective to perform the experimental study on the system using lpg as refrig
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