Adiabatic cooler
MITA Adiabatic cooler General information Adiabatic cooling is a thermodynamic phenomenon by which air temperature is decreased through humidification. The temperature than can be reached is called adiabatic saturation temperature and, depending on the humidification system s efficiency, and it can be much lower than the dry air temperature. MITA adiabatic cooler exploits this principle to improve the finned coil s efficiency, and can be used to cool water/glycol mixtures or to condensate refrigerants. Structural and operating characteristics Finned coil Front view, with manhole Motor-fan group MITA adiabatic cooler has been designed to reduce water consumption, minimize consumption and totally prevent aerosol emissions into the atmosphere. The high saturation efficiency ensured by the special humidifier pack enables the use of a single finned coil provided with many rows, so as to obtain the same performance as traditional systems with a double 2-rows coil. In MITA adiabatic cooler air humidification is obtained by short humidifier pack wetting cycles, at intervals of several minutes, in comparison with traditional systems in which the humidifier pack must be continuously wetted, or water must be constantly sprayed in the air flow. In MITA solution the water required to humidify the air flow is released constantly over time from the pack until the next wetting cycle (in average conditions, 4 to 6 wetting cycles/hour, lasting only a few seconds, are sufficient). Structural characteristics: main components (small basin, body and upper part) made of fibreglass, which is light, corrosion-proof and maintenance-free. The other elements are made of plastic material (water distribution system and air inlet louvers) or of hot-dip galvanized steel (bearing frame) flocked PVC humidifier pack with high water retaining capacity. Its configuration, with large channels, allows the installation of several layers without excessive pressure drops, which permits a considerable efficiency increase in-line arrangement of the different components: the pack is uniformly crossed by the air, allowing homogeneous air saturation; the finned coil, installed in the same section, considerably improves its efficiency. Fans are in line with other components, and therefore the air flow does not change direction, for a better energy saving. In the cold season, the air can be sucked directly by suitable (optional) side dampers, for a further reduction in consumption reduced water consumption, thanks to a better system efficiency. During each wetting cycle, excess water falls into collecting basin, and it is re-used in the subsequent cycle. The basin is only a reserve from which when necessary the pump can pick-up the water required to keep the humidifier pack wet. The control system ensures constant water change and daily draining of the basin the control system has been designed to meet both maximum efficiency/energy saving and low environmental impact requirements. The following parameters are controlled and handled: - outside air temperature beyond the finned coil - inlet / outlet fluid temperature - rotation speed of the fans (frequency inverter-controlled) - automatic shift from dry to adiabatic function and vice-versa - wetting intervals of the humidifier pack and simultaneous fans stop - opening/closing of air by-pass dampers (if provided) Flocked PVC humidifier pack
Structural characteristics 1 9 2 8 3 10 4 11 7 6 5 1 Axial fan 5 Centrifugal water pump 9 Inlet of fluid to be cooled 2 Finned coil 6 Water collecting basin 10 Drift eliminator 3 Air by-pass dampers with servo control (optional) 7 Air inlet louvers 11 Humidifier pack 4 Wetting circuit of humidifier pack, with spraying nozzles 8 Cooled fluid outlet
COOLER OPERATION AND CONTROL LOGIC Cooler operation and control logic The cooler operation is automatically controlled by an electrical board provided with factory-programmed PLC according to the logic explained below. The electrical board can be operated either automatically or in stand-by (the latter mode can be used in case of emergency or for short maintenance works). Two types of operation are programmed in automatic mode: dry operation: in the winter season, when the air is not humidified (the adiabatic circuit is empty). In this case, the air enters the cooler from the top (dampers open, if provided), or crosses the dry humidifier pack (pump circuit off) Dry operation adiabatic operation: in the summer season, when the air undergoes an adiabatic cooling process, the air enters the cooler from the lower part and crosses the humidifier pack (dumpers closed and pump circuit on). Adiabatic operation 40 / 35 / 24 * 45 / 35 / 24 * 35 / 30 / 24 * 40 / 30 / 24 * * FLUID INLET/OUTLET TEMPERATURE AND WET BULB TEMPERATURE ADIABATIC COOLER 2 4 6 8 10 12 Efficiency, in KW 110 220 330 440 550 660 Efficiency, in KW 130 260 390 530 660 800 Efficiency, in KW 64 128 200 265 335 405 Efficiency, in KW 82 165 253 340 430 525 50 / 24 ** 45 / 24 ** 40 / 24 ** ** CONDENSING TEMPERATURE AND WET BULB TEMPERATURE. GAS R 134A ADIABATIC CONDENSER 2 4 6 8 10 12 Efficiency, in KW 160 326 495 660 827 994 Efficiency, in KW 130 260 390 530 660 800 Efficiency, in KW 95 190 295 395 495 595 EXAMPLES OF WATER CONSUMPTION PER M 2 OF SURFACE, UNDER DIFFERENT THERMO-HYGROMETRIC CONDITIONS OF INLET AIR (values referring to maximum heat output) EXAMPLE Dry air inlet temperature ( C) Relative humidity at the inlet (%) Corresponding wet bulb temperature ( C) Adiabatically cooled air temperature ( C) Relative humidity at the outlet (%) Water consumption ( kg / h / m 2 ) Case 1 Case 2 Case 3 Case 4 35 40 23,9 25,4 88 43,78 32 50 23,7 24,9 90 32,32 30 50 22 23,2 90 30,61 28 55 21,2 22,2 91 25,57
TECHNICAL CHARACTERISTICS MITA ADIABATIC COOLER vs TRADITIONAL ADIABATIC COOLER Traditional adiabatic cooler MITA Strenghts Humidifier pack considerable water retaining capacity narrow air channels homogeneous wetting and air saturation large channels, in-line arrangement, with perpendicular positioning to the flow low pressure drops, since air does not spraying system and heat exchange coil direct contact with sunlight change direction no contact with sunlight material: cellulose soaked with resin long life (no contact with UV rays) flocked PVC material rot-proof long life low fouling factor copper pipes with aluminium fins finning with increased spacing arrangement in line with the humidifier pack single 4 or 6-rows coil Finned coil copper pipes with aluminium fins finning with reduced spacing V positioning double 2-rows coil one single high-efficiency coil reduced fouling factor low pressure drops, less consumption 4-5 wetting cycles/hour (10 seconds each) water collecting basin Water consumption (in summer climatic conditions) continuous wetting cycles reduced total water consumption wetting intervals, with fans off all factory-preset parameters are automatically controlled also in the version provided with dampers Control system wetting cycles with fans running dampers not available on all models low water consumption low energy costs low cleaning and maintenance costs no aerosol
DIMENSIONS AND WEIGHTS, without dampers unit TYPE 2 4 6 8 10 12 DIMENSIONS WEIGHT Cooler IN-OUT A B H empty operation Condenser Filling Drain mm mm mm kg kg Ø mm IN Ø mm OUT Ø mm Ø mm Ø mm N x kw kw 2340 1170 2885 740 1050 2 1/2 2 1/2 2 3/4 1 1/2 2 x 2,48 0,55 2340 2340 2985 1170 1700 3 2 1/2 2 3/4 1 1/2 4 x 2,48 1,1 2340 3510 3085 1600 2350 4 2 1/2 2 3/4 1 1/2 6 x 2,48 1,5 2340 4680 3135 2110 3150 4 2 1/2 2 3/4 1 1/2 8 x 2,48 1,5 2340 5850 3185 2690 4000 4 2 1/2 2 3/4 1 1/2 10 x 2,48 2,2 2340 7020 3185 3180 4670 4 2 1/2 2 3/4 1 1/2 12 x 2,48 3 Fan No. / Pump, with dampers unit TYPE 2 4 6 8 10 12 DIMENSIONS WEIGHT Cooler IN-OUT A B H empty operation Condenser Filling Drain mm mm mm kg kg Ø mm IN Ø mm OUT Ø mm Ø mm Ø mm N x kw kw 2340 1170 3435 830 1110 2 1/2 2 1/2 2 3/4 1 1/2 2 x 2,48 0,55 2340 2340 3685 1280 1790 3 2 1/2 2 3/4 1 1/2 4 x 2,48 1,1 2340 3510 3785 1750 2500 4 2 1/2 2 3/4 1 1/2 6 x 2,48 1,5 2340 4680 3835 2300 3300 4 2 1/2 2 3/4 1 1/2 8 x 2,48 2,2 2340 5850 3885 2910 4150 4 2 1/2 2 3/4 1 1/2 10 x 2,48 2,2 2340 7020 3885 3450 4950 4 2 1/2 2 3/4 1 1/2 12 x 2,48 3 Fan No. / Pump Technical data not binding - please contact MITA Technical Dept. for full details. ENG/ Rev.05-10 - Realizzato da: GRUPPO STAMPA GB Via Antonio M. Fontana, 1 Tel. +39 0382.67.599 www.mita-tech.it I - 27010 Siziano (PV) Fax +39 0382.617.640 e-mail: info@mita-tech.it