REFRIGERATION & AIR CONDITIONING
POF VISIT REPORT
INTRODUCTION: The demand for block ice is as great today as it ever has been, despite advances made in the development of modern refrigeration equipment. The chemical and construction industries, for example, commonly use block ice in situations where the use of such equipment may not be practical. The fishing industry is also another major consumer of block ice, which is used to preserve the fish from the time they are caught, until they are sold. It is also used to great extents by the retailers of food and drinks to preserve food and/ or chill drinks. Block ice is the most popular type of ice sold for a variety of reasons. It melts more slowly than other types of ice and thus lasts longer. It can be placed in open truck with only a tarpaulin to protect it from the elements and shipped to a location of four hours away. Its rectangular shape makes it easy to stack of up to 15 meters and store large amounts. Block ice has merits of easy to transport and separate as well. Other types of ice have the tendency to freeze into a solid mass, making it difficult to work with. The ice making plant outlined in this proposal is the result of years of research and development done by FRESER. The plant was designed to operate efficiently in tropical areas, but should prove p rove to be profitable in any climate.
PARTS
OF ICE MAKING PLANT:
The complete ice making plant consists of: I. II. III. IV. V. VI.
Ammonia Compressors Condensers / Heat Exchangers Ammonia Receiver Cooling Coil / Evaporator Chilling Tank Paneling (Electrical Equipments) i.
AMMONIA COMPRESSORS:
Ammonia compressors designed with state-of-the-art technology for industrial & commercial refrigeration and low temperature applications.
1|Page
REFRIGERATION & AIR CONDITIONING
POF VISIT REPORT
Compressors are V belt driven and are suitable to operate with Ammonia (NH3) & Freon [12 (CCl 2F2), 22 (CHClF2)] as refrigerant. Robust construction, excellent performance and power saving features and hallmarks of the products. ii.
CONDENSERS/HEAT EXCHANGERS:
Condenser is a heat transfer surface, generally which are divided in to three types.
Air Cooled Condenser: Employ air as the condensing medium.
Water Cooled Condenser: Utilize water to condense the refrigerant.
Evaporative Condenser: Use both air and water as the condensing medium. The function of the air is to increase the rate of evaporation by carrying away the water vapor results from evaporation process. iii.
Ammonia receiver can control the supply and demand relation between the condensers and the evaporator, prevent excessive liquid ammonia from staying in the condenser, maintain a certain level in the liquid receiver to prevent gas from going into the liquid pipe line. The ammonia in the system can be stored in the ammonia receiver to avoid loss of the ammonia before the refrigerating system is repaired. Therefore, the volume of the ammonia storage should be considered before buying it. iv.
AMMONIA RECEIVER:
COOLING COIL/EVAPORATOR:
Cooling Coil / Evaporator is used as heat transfer surface in which a volatile liquid is vaporized for the purpose of removing heat from refrigerated space. V shape cooling coils are available in different sizes, usually custom made to the individual applications. v.
CHILLING TANK:
Chilling Tank consists of three parts: A) Ice Tank
2|Page
REFRIGERATION & AIR CONDITIONING
POF VISIT REPORT
B) Insulation of Ice Tank C) Ice Block A) ICE TANK: Ice tanks are made of such material as wood, steel or concrete. As wooden tanks do not last long enough and are liable to leak, they should preferably be made of steel well coated with waterproof paint. Tanks made of reinforced concrete are also recommended as superior to those of wood. The ice tank contains the direct expansion coils, equally distributed throughout the tank and these coils are submerged in brine. The tank is provided with a suitable frame of hard wood for support the ice cans and a propeller or agitator for keeping the brine in motion: the brine in the tank acts as a medium of contact only, the ammonia evaporating in the ice coils extracts the heat from the brine, which again absorbs the heat for the water in the cans. The tank itself should not be much larger than is necessary to hold the cans, the coils, and the agitator. About two inches should be left between the moulds and three inches between the pipes and the moulds.
B) INSULATION OF TANK: Insulation of the ice tank is accomplished by using twelve to eighteen inches of good insulating material on each of the sides and not less than twelve inches under the bottom. C) ICE BLOCK: Commercial sizes of Ice cans vary with the weight of ice cakes required. The cans are made to contain about 5% more than their rated capacity to compensate for thawing. vi.
Paneling (Electrical Equipments) :
The Neer Ice making plant is furnished with electrical control panel with compressor starter, all necessary safety switches and press stats, Voltmeter, Ammeter, Temperature Sensor etc.
3|Page
REFRIGERATION & AIR CONDITIONING
CAPACITY,
POF VISIT REPORT
PROCESS CYCLE AND ITS
LAYOUT: Ice cans are placed in can grids and moved to beneath the filling tank which automatically fills each can with proper level of pre-cooled water and then stop. Potable water must be used to make ice intended for human consumption. The cans are then hoisted and carried to the brine tank and immersed inside. The brine, which is a calcium chloride solution kept at a 4|Page
REFRIGERATION & AIR CONDITIONING
POF VISIT REPORT
temperature of -10℃, is constantly circulated by agitator in order to keep the temperature consistent throughout the tank. Air is blown into the center of the can to induce a swirling motion. This causes any impurities and air bubbles in the water to be collected in the center of cans. Prior to finish freezing, this core is removed by a suction pump and replaced with fresh pre-cooled water. The time required for the water to be frozen varies according to the size of cans being used, 150lbs. block requires 24 hours, 300 lbs. Takes 48 hours. When the ice has completely formed, the grids are lifted up from the brine tank and moved to place in the thawing tank. Using the warm water heats the can, until the ice allowed to be slid out. The block ice is then removed from the can by a can dumper. In POF 150 block per day are going manufactured and mass of each block is 50KG. The capacity of that plant is 3.5 TONS, installed on1981. The empty cans are returned to filling tank for next ice making cycle. The ice is moved to ice storage and stacked by an ice stacker, or it can be delivered to customer right away upon requested.
VAPOUR COMPRESSION REFRIGERATION:
Vapor-compression refrigeration is one of the many refrigeration cycles available for use. It has been and is the most widely used method for airconditioning of large public buildings, offices, private residences, hotels, 5|Page
REFRIGERATION & AIR CONDITIONING
POF VISIT REPORT
hospitals, theaters, restaurants and automobiles. It is also used in domestic and commercial refrigerators, large-scale warehouses for chilled or frozen storage of foods and meats, refrigerated trucks and railroad cars, and a host of other commercialandindustrialservices. Oilrefineries, petrochemical and chemical pro cessing plants, and natural gas processing plants are among the many types of industrial plants that often utilize large vapor-compression refrigeration systems. Refrigeration may be defined as lowering the temperature of an enclosed space by removing heat from that space and transferring it elsewhere. A device that performs this function may also be called a heat pump.
The vapor-compression uses a circulating liquid refrigerant as the medium which absorbs and removes heat from the space to be cooled and subsequently rejects that heat elsewhere. Figure 1 depicts a typical, single-stage vapor-compression system. All such systems have four components: a compressor , a condenser , a Thermal expansion valve (also called a throttle valve or Tx Valve), and an evaporator. Circulating refrigerant enters the compressor in the thermodynamic state known as a saturated vapor and is compressed to a higher pressure, resulting in a higher temperature as well. The hot, compressed vapor is then in the thermodynamic state known as a superheated vapor and it is at a temperature and pressure at which it can be condensed with typically available cooling water or cooling air. That hot vapor is routed through a condenser where it is cooled and condensed into a liquid by flowing through a coil or tubes with cool water or cool air flowing across the coil or tubes. This is where the circulating refrigerant rejects heat from the system and the rejected heat is carried away by either the water or the air (whichever may be the case). 6|Page
REFRIGERATION & AIR CONDITIONING
POF VISIT REPORT
The condensed liquid refrigerant, in the thermodynamic state known as a saturated liquid, is next routed through an expansion valve where it undergoes an abrupt reduction in pressure. That pressure reduction results in the adiabatic flash evaporation of a part of the liquid refrigerant. The autorefrigeration effect of the adiabatic flash evaporation lowers the temperature of the liquid and vapor refrigerant mixture to where it is colder than the temperature of the enclosed space to be refrigerated. The cold mixture is then routed through the coil or tubes in the evaporator. A fan circulates the warm air in the enclosed s pace across the coil or tubes carrying the cold refrigerant liquid and vapor mixture. That warm air evaporates the liquid part of the cold refrigerant mixture. At the same time, the circulating air is cooled and thus lowers the temperature of the enclosed space to the desired temperature. The evaporator is where the circulating refrigerant absorbs and removes heat which is subsequently rejected in the condenser and transferred elsewhere by the water or air used in the condenser. To complete the refrigeration cycle, the refrigerant vapor from the evaporator is again a saturated vapor and is routed back into the compressor.
REFRIGERANTS: There are three specific types of refrigerants used in refrigeration and airconditioning systems: 1. Chlorofluorocarbons or CFCs, such as R-11, R-12, and R-114 2. Hydrochlorofluorocarbons or HCFCs, such as R-22 or R-123 3. Hydrofluorocarbons or HFCs, such as R-134a. All these refrigerants are "halogenated," which means they contain chlorine, fluorine, bromine, astatine, or iodine. Refrigerants, such as Dichlorodifluoromethane (R-12), Monochlorodifluoromethane (R-22), and Refrigerant 502 (R-502), are called PRIMARY REFRIGERANTS because each one changes its state upon the application or absorption of heat and, in this act of change, absorbs and extracts heat from the area or substance. The primary refrigerant is so termed because it acts directly upon the area or substance, although it may be enclosed within a system. For a primary refrigerant to cool, it must be placed in a closed system in which it can be controlled by the pressure imposed upon it. The refrigerant can then absorb at the temperature ranges desired. If a primary refrigerant were used without being controlled, it would absorb heat from most perishables and freeze them solid. 7|Page
REFRIGERATION & AIR CONDITIONING
POF VISIT REPORT
APPLICATIONS:
Ice Making plants are used in different applications like :
Fisheries Hospital Chemical Pharmaceutical Commercially used in different industrial applications
8|Page
