In many fields of industry cooling of technological processes, refrigeration supply to cold rooms is realized by means of intermediate refrigerant. Water, water solution of glycol and propylene glycol, CaCl2, NaCl, and other different substances are applied as refrigerating fluids.
So-called icy water with the temperature near to 0°Ñ is widely used in the food industry and air conditioning systems. At totality properties required to the refrigerating fluids: low velocity, high density, high heat conductivity and heat capacity, safety and harmless, chemical resistance in regard to metal, no deficiency and cheapness – the refrigerating fluid is an ideal agent. However, temperature range of water application is extremely limited: at the low negative boiling temperature of refrigerant in evaporator the danger of freezing and damage of heat exchange equipment arise. Risk of evaporator failure (shell and tube, plate type, tub-in-tube) at water cooling to the temperature near crystallization temperature makes its application undesirable and often impossible. Coil–in-box evaporators are the best solution, while its usage allows to obtain water temperature +0,2…1°Ñ.
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Application:
Dairy factories, breweries, air-conditioning systems are distinguished by considerable uneven heating load during 24 hours- often, peak hours of heating load can take place for some hours only during the day. Cooling of these heating loads by refrigerating equipment, chosen at maximum load, results in equipment operation with underloading during long period of time and in considerable increase of capital expenses for creation of refrigerating units.
The application of ice accumulators allows choosing necessary refrigerating capacity of equipment not at peak heating load but less considerably, about 30-50% from that which would be necessary for compensation of peak heating load. Over refrigerating capacity during little heating load hours (usually at night) is consumed for cold accumulation as ice that frozen on the surface of coil-in-box evaporator. When heating loads increase to peak magnitudes the deficiency of cold is filled by ice melting.
Advantages of application:
So ice accumulator is a unit, which accumulates energy as water ice. Ice freezes on the surface of coil or panel evaporator, which is installed in insulated water tank. At intense ice melting in peak hours of heating load icy water is forming with the temperature about +1°Ñ, which is used for quick cooling of products.
Main advantages of ice accumulators:
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possibility of obtaining icy water and keeping its temperature in the range from +0,2°Ñ to +2°Ñ due to ice melting at any change of heat load;
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possibility of a quick beat down of peak heating load;
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considerable reduction of desirable refrigerating capacity and the set capacity of compressor and auxiliary equipment;
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reduction of electric energy consumption for cold output, while ice is freezing usually in night hours, when plant operates at lower condensation temperature;
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reduction of maintenance expenses, while the equipment operates in night hours at the preferential energy tariff;
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high reliability and durability of refrigerating plant due to more even operating conditions because of 24 hours schedule of heating loads.
Distinguishing features of ice accumulators of Aircool Co:
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electronic control of ice thickness;
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compact dimensions due to optimal construction of coil evaporator;
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possibility of production evaporator of two types – made of galvanized steel or of stainless steel;
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application of ozone-friendly refrigerants;
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to increase the intensity of ice melting a special system special system of air supply to the tank is applied;
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fully- automatic refrigerating unit.
Standard ice accumulators include:
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coil-in-box evaporator;
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air distribution system made of plastic tubes;
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air blower, pumping air in plastic tube system;
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control system of ice thickness;
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an insulated tank of stainless steel.
The engineers of Aircool Co have designed a series of compressor-condenser units special for application in refrigerating circuit with ice accumulators. Refrigerating units AK are made on the basis of semihermetic compressors BITZER, heat exchanger equipment GÜNTNER, ALFA LAVAL, and so refrigerating automatic and shutoff valves DANFOSS, ALCO CONTROLS.