AHU for Chiller System in A Basketball Gym

AHU (Air Handling Unit) is the core equipment to realize indoor temperature and humidity control and air quality assurance. Since the basketball hall is characterized by high space, dense personnel, and large fluctuation of heat and humidity load, its AHU design needs to take into account comfort, energy saving and system stability.

Core Functions and Scenario Requirements of AHU in Basketball Arena

1. Load Characteristics and Processing Objectives

Characteristics of Heat and Humidity Load:

Heat production is about 120~180W/person and humidity production is about 60~90g/h/person when people are exercising, and the peak load is concentrated in the time of game or training (e.g., spectator stand + athletes' area is full at the same time).

There is obvious thermal stratification phenomenon in high space (floor height usually ≥12m), the temperature at the top is 5~8℃ higher than that on the ground, and it is necessary to reduce ineffective energy consumption through airflow organization.

Temperature and humidity control target:

Competition period: temperature 24~26℃, humidity 50%~60% (to avoid slippery floor and athletes' discomfort);

Non-competition period: temperature 16~18℃, humidity ≤60% (energy-saving operation + moisture-proofing of equipment).

2. Air quality and special needs

Fresh air volume standard: calculated according to the density of personnel (≥30m³/h/person), or according to the building area (≥2 times /h air changes), take the larger value (such as 1000 people need to be fresh air volume of 30,000m³/h venues).

Dust and odor control: the smell of snacks in the audience area and the sweat in the sports area should be handled by medium-effect filter (F7 level) + activated carbon adsorption section to avoid secondary air pollution.

Key elements of AHU system design

1. Unit form and layout

Combined AHU selection:

Typical module configuration: fresh air section + mixing section + filtration section + surface cooling/heating section + humidification section + fan section + muffling section (adjusted according to climate zone).

Example: 10,000 square meters basketball court (15m high) needs AHU air volume of about 150,000~200,000m³/h, corresponding to the cooling capacity of 1000~1,500kW (cooling load index 80~120W/m2).

Optimization of installation location:

Priority is given to the mezzanine floor or rooftop room of the stadium to shorten the length of air ducts (to reduce the resistance along the way by 10-15 Pa/m);

To avoid the vibration of the unit to be transferred to the competition venue, a spring shock absorber (intrinsic frequency ≤5Hz) + flexible duct connector should be set up.

2. Air treatment process and parameters

Summer condition treatment process: fresh air (35℃/65%RH) + return air (28℃/60%RH) → mixing section → medium effect filter → surface cooler (7℃ chilled water) → dehumidification to 12g/kg → fan pressurization → noise cancellation → air supply (18~20℃/55%RH)

Surface cooler design: 3 rows of copper tubes + aluminum fins (fin spacing of 3mm), head-on Wind speed 2.5~3m/s, chilled water flow rate 1.5~2m/s (to ensure that the heat transfer coefficient ≥250W/m2・K).

Processing flow in winter conditions:

Fresh air (-5℃/70% RH) → Preheating section (hot water coil) → Mixing section → Filtration → Heating + humidification → Air supply (18℃/45% RH)

Humidification: choose electrode humidifier (fast response, suitable for rapid adjustment of humidity in a large space), humidification calculated at 5~8g/kg (such as the air volume of 200,000 m³/h, humidification of about 1,600kg/h). 3. Airflow organization and energy-saving design

3. Airflow organization and energy-saving design

air supply mode:

air supply in layers in large space: adopting nozzle side sending (range 15-20m) + lower return air, only supplying cold to the activity area below 2m on the ground (energy saving of 30% compared with air conditioning of the whole space);

Cyclone air outlet is set up separately in the auditorium (wind speed ≤2m/s), avoiding the cold wind blowing directly on the human body.

Energy-saving measures:

heat recovery device: rotary heat exchanger (sensible heat recovery efficiency ≥70%) is installed to recover heat from the exhaust air to preheat the fresh air in winter (saving 25% of heating energy);

frequency conversion control: the fan adopts a frequency conversion motor (the wind volume is automatically adjusted according to the concentration of indoor CO₂, and the wind volume can be lowered to 60% of the rated value at the time of low load).

Technical Challenges and Responses under Special Scenarios

1. Load Fluctuation and System Adjustment

Dynamic Load Handling:

Competition / Training Time (Full Load): AHU running at full airflow, chilled water temperature 7℃;

Non-full time: Linking chiller through BA system to reduce the water flow rate of the meter cooler (e.g. down to 50%), and at the same time lowering the speed of the fan (avoiding "big horse pulling small car ").

Transitional season operation:

When the outdoor temperature is ≤24℃, turn on the full fresh air mode (shut down the table cooler) and utilize the natural cooling source to cool down the temperature (the energy saving rate can be up to 40%), and pay attention to the upgrading of the fresh air filtration precision (e.g. increase the G4 pre-filtration).

2. Noise control and moisture-proof design

Noise limit:

Noise ≤ 65dB at 1m outside the machine room, noise ≤ 45dB in the competition area, impedance composite muffler (insertion loss ≥ 30dB) should be installed at the fan outlet, and the air duct is wrapped with acoustic cotton (thickness of 50mm, noise reduction of 15~20dB).

Anti-moisture and anti-corrosion treatment:

Hydrophilic aluminum foil fins are used in the surface cooler (to reduce condensate retention), and an inclined water catching tray is set at the bottom (slope ≥3%) + electric heating (to prevent freezing and cracking in winter);

The AHU box in coastal area is made of 316L stainless steel (to resist corrosion by salt spray), and the internal components are coated with epoxy coating (dry film thickness ≥200μm).