How to calculate air compressor displacement and equipment gas consumption

The calculation of air compressor displacement and equipment gas consumption should be combined with theoretical formulas, measured data and system matching principles. The following is a step-by-step guide:

calculation of 1. air compressor displacement

1. Theoretical displacement (standard condition)

• piston air compressor:

Qth = 4 & pi;D2 ×S×n× & eta; Capacity

• d: cylinder diameter (m),S: piston stroke (m),n: speed (r/min)

• & eta; capacity: volumetric efficiency (0.85-0.95)

• screw air compressor:

Qth = volume between teeth of 2V rotor × n× & eta; Capacity

2. Actual displacement correction

consider temperature, pressure, leakage, etc:

Q real = Qth×P suction p row ×T row t suction × & eta; Temperature rise × & eta; Machinery

• P row/P suction: compression ratio
• T suction/T row: temperature correction coefficient (to check enthalpy-humidity chart)

calculation of gas consumption of 2. equipment

1. Steady-state equipment

• direct measurement method: Use vortex flowmeter or thermal mass flowmeter to measure instantaneous flow and take statistical average.

• Formula calculation:

Q = pressure × efficiency equipment power × unit energy consumption coefficient

2. Pulse gas equipment

• peak flow method:

Q peak = t pulse tank volume ×(Pmax & minus;Pmin ) × safety factor

• statistical law: Record the number of pulses per unit time and the amount of gas used each time.

3. system matching principle

1. redundant design:

   • total displacement of air compressor = gas consumption of equipment × (1 + leakage coefficient) × (1 + expansion coefficient)
   • typical value: leakage coefficient 5%-10%, expansion coefficient 15%-20%

2. pressure loss correction:

Q needs = Q × P empty P × & eta; Pipe network 1

• & eta; pipe network: pipe network efficiency (0.9-0.95)

3. parallel connection of multiple devices:
   • calculate equal utility gas volume: Q total = & sum;Qi3

4. measurement verification method

1. deploying Sensor Networks:
   • install pressure/temperature sensors at the outlet of the air compressor, the inlet of the gas equipment, and the gas storage tank.
   • Multi-node monitoring using ultrasonic flow meters
2. data acquisition and analysis:
   • construction of gas consumption-time curves to identify peak demand
   • calculation of pressure decay rate to verify tank matching

5. Industry Case Reference

• scene photovoltaic silicon wafer cutting workshop (gas pressure 7bar)
• configuration: 3 screw air compressors (single 40m & sup3;/min)+10m & sup3; gas storage tank
• measured data:
  • gas consumption of equipment: 35m & sup3;/min (steady state), up to 38m & sup3;/min during pulse
  • by optimizing the pipeline layout, the pressure loss is reduced from 0.8bar to 0.5bar, and the efficiency of the air compressor is improved by 8%

it is recommended to dynamically match the original performance curve of the air compressor with the load curve of the gas equipment, and if necessary, use the variable frequency air compressor or install the energy recovery device to optimize the system energy efficiency.