A Total Air Volume Control Method of Variable Air Volume Air Conditioning System Based on Operation Curve

Abstract

The present invention provides a method for controlling the total air volume of a variable air volume air-conditioning system based on an operating curve, comprising: Step 1: obtaining the resistance characteristic curve a of the piping system, and its mathematical expression is: P=S a ·Q 2 , P represents pipeline resistance, the unit is Pa; S a Indicates the pipeline resistance coefficient; Q indicates the air volume, the unit is m 3 / h; Step 2: Obtain the characteristic curves of the fan at various speeds, including P-Q curves and N g ′-Q curve, P represents the pressure head of the fan, the unit is Pa, Q represents the air volume, the unit is m 3 / h,N g ′ is the input power of the motor at various speeds, the unit is kW; Step 3: Solve the operation curve c of the fan; Step 4: Determine N g ′‑f curve, where f represents the operating frequency of the fan motor, in Hz; Step 5: implement total air volume adjustment and control according to the operating curve c of the fan. This method is simpler than static pressure control in terms of control form, and belongs to partial feedforward control, and the adjustment is faster and more stable.

Description

technical field [0001] The invention relates to a variable air volume control method for a central air conditioner, in particular to a total air volume control strategy for a variable air volume (VAV) air conditioning system. Background technique [0002] The central air-conditioning variable air volume system refers to an air-conditioning system in which the air-conditioning system automatically adjusts the air supply volume according to regional load changes and requirements. The variable air volume system can overcome that the constant air volume air-conditioning system only uses one air supply parameter, which cannot meet the requirements of different rooms or different areas. The problem of different indoor air environment requirements can also avoid the intolerable problems of indoor ceiling condensate and mold pollution that are often accompanied by fan coil systems. For large air-conditioning systems, it can effectively save operating costs. [0003] There are three...

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Problems solved by technology

However, the air volume control method in the prior art inevitably uses a pressure detection device, or the valve position signal and air volume value of the terminal device, thus facing the problems of pressure fluctuation and turbulent flow in the air duct that are often encountered in static pressure measurement, and adjusting The hysteresis problem is relatively complicated in the control form, and has some approximate assumptions, and belongs to feedback control and pressure control, the adjustment speed is slow and not smooth enough, and the control accuracy is not high

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