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Air-handling process
Air-handling process of fan-coil unit with fresh air system
Occupant density of the hotel guest rooms is low so the demand of fresh air is not great. We choose ceiling air conditioning units as the fresh air handling units to process the fresh air to the indoor air isenthalpic line. Air handling process is given in Fig.1.
Air-handling process of primary return air system
Primary return air system is adopted for the 1st and 2nd floor of the dinning hall. Air handling process is given in Fig.2.
Air-handling analysis of the private rooms and the VRV system
Fresh air is handled to a higher enthalpy state than the indoor isenthalpic line by the full-heat type fresh air exchanger. The fan-coil units not only take partial load of the fresh air but also take full of the indoor cold load and wet load.
Parameters of outdoor air:
Dry bulb temperature t=33.5℃ , Relative Humidity =64.9% , enthalpy i=89.7kJ/kg
Final parameters of the fresh air:
tl t t t3 33.5 0.6333.5 2528.14 (℃) (1)
il i i i3 89.7 0.6389.7 56.268.6 (kJ/kg) (2)
in the equations:
t3——exhaust inlet temperature ℃；
i3——exhaust inlet enthalpy kJ/kg；
——efficiency of all-heat exchanger , about 63%；
Fig.1 Enthalpy handling process of guest rooms Fig.2 Air handling process of the
primary return air system
Design of the ventilation and smoke exhaust system
Design of the wind exhaust system
Air-conditioned room is guaranteed 5 ~ 10Pa positive pressure. We need to set mechanical ventilation to avoid too much positive pressure and the exhaust air rate should be calculated to maintain the balance. If a bathroom is set up in the air conditioning room and it’s exhaust air rate fulfill the demands, the exhaust system is not necessary for the air conditioning room. The exhaust air rate is calculated by the ventilation rate: bathroom in the guest room takes 5 to 8 times / h and public toilet takes 10 to 15 times / h.
Design of the smoke exhaust system
A vertical system is set up in the middle of the corridor(2nd to 7th floors, length of 40.35m, width 2.1m). According to the provisions of practical heating and air conditioning design manual: air
volume of the mechanical exhaust system shall not be less than 7200 m3/ h, so the system's total air volume is 7200 m3 / h. The exhaust duct is concrete duct with smooth surface so take the outlet wind speed as 16 m/s and the cross-sectional area of the outlet tuyere is 0.125 m2 .Select the normally closed exhaust port. Only open the exhaust port of the fire floor when a fire occurs. Exhaust port should have a manual and automatic opening device. Exhaust port and exhaust valves should be interlocked with the exhaust fan. When any level of the exhaust port or exhaust valves opens, the exhaust fan should be able to start immediately. Exhaust fans are advised to use axial fans which
ensure continuous operation at 280 ℃ for at least 30 minutes.
Design of the Pressurized air supply system
The height of the building doesn’t exceed 50m, according to the provisions of practical heating and air conditioning design manual: pressurized air supply system is only set in the stairwell and elevator room. The pressurized air supply volume calculated by differential pressure method and anemometer algorithm is 18946.7 m3/h and 23760 m3/h,respectively. Finally identified as 23760 m3/h.
Conclusions
By comparison and selection of air-conditioning systems, the design uses three kinds of air conditioning systems in the form, in particular: dining hall, open office area using primary return air system; fan-coil units with fresh air system is adopted for the guest rooms of the hotel and private dining rooms; large conference rooms using varied refrigerant volume air conditioning system (VRV). Design of the water system: the direct return system is adopted for the 1st and 2nd floor of the dinning room and other area using the indirect return system. Air conditioning systems are set up