Compressor (engineering)
A compressor is a mechanical device that increases the pressure of a gas by reducing its volume, thereby increasing its energy content. Compressors are fundamental components in refrigeration systems, gas turbines, pneumatic tools, and industrial processes where pressurised gas is required. The work input to a compressor is governed by thermodynamic principles, and the efficiency of the compression process determines overall system performance.
Key Formula
W_comp = m_dot × c_p × (T2 - T1)
LaTeX: W_{comp} = \dot{m} \cdot c_p \cdot (T_2 - T_1)
| Symbol | Meaning | Unit |
|---|---|---|
| W_{comp} | Compressor power input | W |
| \dot{m} | Mass flow rate of gas | kg/s |
| c_p | Specific heat at constant pressure | J/(kg·K) |
| T_1 | Inlet temperature | K |
| T_2 | Outlet temperature | K |
Worked Example
Problem
Air enters a compressor at 300 K with a mass flow rate of 2 kg/s. The outlet temperature is 480 K and c_p for air is 1005 J/(kg·K). Calculate the power input required.
Solution
Step 1: Identify given values — ṁ = 2 kg/s, T1 = 300 K, T2 = 480 K, c_p = 1005 J/(kg·K). Step 2: Apply the compressor power formula: W = ṁ × c_p × (T2 − T1). Step 3: W = 2 × 1005 × (480 − 300) = 2 × 1005 × 180.
Answer
W = 361,800 W ≈ 362 kW
Types of Compressors and Their Characteristics
| Type | Mechanism | Typical Pressure Ratio | Application |
|---|---|---|---|
| Reciprocating | Piston-cylinder | 5:1 to 100:1 | Refrigeration, CNG |
| Centrifugal | Rotating impeller | 2:1 to 10:1 | Gas turbines, HVAC |
| Axial | Rotating blades | 5:1 to 30:1 | Jet engines |
| Screw | Meshing helical rotors | 3:1 to 15:1 | Industrial air supply |
| Scroll | Orbiting scroll | 2:1 to 8:1 | Air conditioning |
Interactive Tools
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Related Terms
Heat Exchanger
A heat exchanger is a device designed to transfer thermal energy between two or more fluids at different temperatures, without the fluids mixing. Heat exchangers are ubiquitous in engineering applications including power generation, chemical processing, HVAC systems, and automotive radiators. The rate of heat transfer depends on the temperature difference, the overall heat transfer coefficient, and the heat transfer area.
Thermodynamic Cycle (engineering)
A thermodynamic cycle is a series of thermodynamic processes that return a system to its initial state, enabling continuous conversion of heat into work or vice versa. Engineering thermodynamic cycles such as the Rankine, Brayton, and Otto cycles form the basis of power plants, jet engines, and internal combustion engines respectively. The thermal efficiency of a cycle quantifies the fraction of heat input that is converted into net work output.
Engineering Nozzle
An engineering nozzle is a shaped duct or orifice designed to accelerate a fluid by converting pressure energy into kinetic energy, thereby increasing the fluid's velocity. Nozzles are critical components in rocket engines, gas turbines, steam turbines, and fluid spray systems. In a converging nozzle, the cross-sectional area decreases in the flow direction, while a converging-diverging (de Laval) nozzle is used to achieve supersonic flow.
From Latin "comprimere" meaning "to press together", from "com-" (together) and "premere" (to press). The mechanical use of the term became common in the 19th century with the development of steam and pneumatic machinery.