Refrigeration an Air conditioning-4.pptx

HVAC

1. Refrigeration and Air conditioning RAC

2. In a space, the sensible heat load is 13.5 kW and the latent heat load is 3.4 kW. Outside air is at 32°C and 50 per cent relative humidity. The space is to be maintained at 25°C dry bulb and 18°C wet bulb temperatures. All outside air is supplied with reheater to satisfy the space conditions. The conditioned air leaves the supply fan at 17°C. Determine (a) the refrigeration load, (b) the capacity of the supply fan, and (c) the heat supplied in the reheater. (Specific heat of dry air =1.0062 kJ/ kg.K Latent heat of vaporization=2500 kJ/kg) 1 4 4 3 2

3. Central air conditioning system Zones and system: Internal load (lights, people, electrical devices) External load (Solar radiation, outside air temperature) Room A and Room B have different space, temperature (Thermostat in each room) 1) Separate air conditioner 2) Separate thermostat for each room to maintain the uniform temperature for central air conditioning system

4. Central Air conditioning system Single zone system:

5. Single zone Mixing of two air Bypassing method

6. Reheat system

7. Multizone system 12-14 zones Small and medium sized application Disadvantage: Humidity control