HVAC (pronounced either 'H-V-A-C' or'aitch-vak') is an acronym that stands for the closely relatedfunctions of 'Heating, Ventilating, and Air Conditioning'- thetechnology of indoor environmental comfort. HVAC system design is a majorsubdiscipline of mechanical engineering, based on the principles ofthermodynamics, fluid mechanics, and heat transfer.
Methods and equipments 空气处理方法和设备
Air heating methods 空气加热方法
Air cooling methods 空气降温方法
Air humidifying method 空气加湿方法
Air dehumidifying method 空气减湿方法
Air heating methods 加热
Classification of heater in AC system 空调常用加热器：
☆ Surface heater (Heatingmedia such as steam, hot water, etc) 表面式空气加热器(热媒为蒸汽或热水)
☆ Electric heaters 电热丝发热
Cooling methods 降温方法
Surface-type Cooler is used for cooling表冷器实现空气的降温
Gilled tube cooler 肋片管式换热器。
Cooling media such as refrigerants ,cold water, etc 冷器内流动的冷媒有制冷剂或冷水(深井水、冷冻水、盐水)等。
Cold source: chilled water (Centralproduced)冷源：冷冻水 (集中制备、循环管网供水)
Refrigeration method 冷源制冷方式:
Compression-type refrigeration 压缩式制冷
LiBr Absorption Refrigeration 溴化锂吸收式制冷
Cooling water 是冷却水，chilledwater 是冷冻水circulation pipe network
Air conditioning system composition 空调系统构成方式
Control circuit 空调系统控制电路
Development of the control circuit
1 Relay control 继电控制
2 Single chip microcomputer or PLCcontrol 单片机或PLC 控制
3 DDC control
Room temperature：
热敏电阻 thermistor
Transmitter 变送器
A thermistor is a type of resistorwhose resistance varies with temperature. The word is a portmanteau of thermaland resistor. Thermistors are widely used as inrush current limiters,temperature sensors, self-resetting overcurrent protectors, and self-regulatingheating elements.
电网电压监控：参考电压—二极管整流 —送入模拟通道，用于保护—过高过低压缩机停止运行。
Air handling system– closed air duct
风处理系统--闭合的风道
■Fresh air新风
■Return air回风
■Air outlet 排风
■Air inlet送风
Differential pressure switches can beplaced on the filter to determine if it is dirty.
防冻开关 Chilled water low tempswitch
sensors are most often used formeasuring the level of carbon dioxide
