Translation Portuguese

Home>>Laboratories>>Refrigeration and Air Conditioning Laboratory

 

REFRIGERATION AND AIR CONDITIONING LABORATORY

 

The UNIFEI Refrigeration and Air Conditioning Laboratory presents an air conditioner with the following characteristics:

• Horizontal geometry, built with metal plate isolated with Expanded Poly-Styrene;
• Double suction Limit Load centrifugal fan, with horizontal discharge, 5000 m3/h air output at 10 ° C, 160 mmCA total static pressure, being driven by a 5 CV three-phase electric engine;
• For air cooling, the conditioner is equipped with a chilled water coil built in copper tubes with ½'' of diameter, with 8 aluminum fins per air, 12 tubes in face, 800 mm long, 380 mm high, 1¼‘' connection, with 8 circuits and 3 rows. The laboratory also has coils with 4, 6 and 8 rows that may be used replacing the 3 row coil;
• For controlling chilled water output, there is a three-way valve, in the inlet of the coil, operated by a servomotor. The original control of this valve, of the electromechanical proportional type, will shortly be replaced by one control of the computerized proportional-integral-derivative (PID) type;
• The conditioner still has a humidification system by immersion resistance, air filters, drift eliminators and dampers to regulate air output.

 

Partial view of the Refrigeration and Air Conditioning Laboratory

 

After leaving the air conditioner, the air is taken through a network of pipes until the diffusers installed in the roof of two rooms (not shown in the Figures) for an experimental simulation of acclimated environments. These rooms may operate independently, that is, the air may be insufflated in only one or in both rooms simultaneously. The room dimensions are 5.0 m x 6.0 m x 3.0 m , and it is built in demountable panels, isolated by 100 mm thick Expanded Poly-Styrene boards. Both rooms have sealed doors and electric resistance battery in their inside in order to simulate the thermal load of the environment.

In the return duct, there is a mixing box to mix the air streams coming from both rooms, and introducing the external air for renewal. With the objective of simulating various external conditions, the following is part of the external air intake:

• Three heating electrical resistance batteries with maximum power of 12 kW;
• An air humidifying system by means of immersion electrical resistances;
• A cooling coil fed with chilled water and whose capacity control is performed by means of a three-way diverter valve operated by a servomotor.

The chilled water used by the air conditioner is produced by a cooler which has:

• A condensing unit with water-cooled compressor and condenser, of the tube-shell type (RADIO FRIGOR - model 7,5);
• Alternative compressor, of the open type, with refrigeration capacity of 24000 kcal/h at the vaporizing temperature of 0 ° C and condensation temperature of 40° C (RADIO FRIGOR – VII-W), operated by means of a15 HP three-phase electric engine;
• Thermostatic expansion valve with external equalizer (Frigor - TADX 7,5 model);
• Evaporator made up of 10 coils, manufactured in copper tubes with the diameter of 5/8” and length of 18 m , being installed inside a water tank.
• Start-up alleviator system;
• Liquid line solenoid valve;
• Manostat;
• Liquid Display;
• Filter Drier;
• Manometer.

The water tank in which the evaporator is submerged is manufactured in isolated metallic plates isolated by 100 mm thick Expanded Poly-Styrene and covered with durable plastic laminate (Formica). The dimensions are 0.75 of width, 1.75 m of length and 0.80 m of depth.

To cool condensation water, there is a cooling tower of the compact countercourrent type (ALPINA - OSVH-8 model), built in strengthened plastic, with the cooling capacity of 9.0 m3/h of water from 31 o C to 27 o C, with wet bulb air temperature of 24 o C.

 

The air conditioning system is also fitted with orifice plates to measure the chilled water output and conditioned air output, rotameter for measuring condensation water output, temperature probes for assemblies in rooms and ducts, manometers, wattmeter and other control and measuring equipment. It should be highlighted that soon all pressure and temperature readings of the cooling cycle as well as all temperature and air relative humidity readings in the conditioner will be completely computerized. Thus, it will be possible to obtain more reliable measures and perform a closer follow-up of the operation of the system.

Besides this air conditioner, the UNIFEI Refrigeration and Air Conditioning Laboratory has a low temperature cooling system with water condenser and open alternative compressor, with 5 TR capacity. This system may be used to produce ice or to cool a room cooling down to -35º C.